The DCC is a DMA Engine designed to capture and store data
during system crash or software triggers. The DCC operates
based on user inputs via the sysfs interface. The user gives
addresses as inputs and these addresses are stored in the
dcc sram. In case of a system crash or a manual software
trigger by the user through the debugfs interface,
the dcc captures and stores the values at these addresses.
This patch contains the driver which has all the methods
pertaining to the debugfs interface, auxiliary functions to
support all the four fundamental operations of dcc namely
read, write, read/modify/write and loop. The probe method
here instantiates all the resources necessary for dcc to
operate mainly the dedicated dcc sram where it stores the
values. The DCC driver can be used for debugging purposes
without going for a reboot since it can perform software
triggers as well based on user inputs.
Also added the documentation for debugfs entries and explained
the functionalities of each debugfs file that has been created
for dcc.
The following is the justification of using debugfs interface
over the other alternatives like sysfs/ioctls
i) As can be seen from the debugfs attribute descriptions,
some of the debugfs attribute files here contains multiple
arguments which needs to be accepted from the user. This goes
against the design style of sysfs.
ii) The user input patterns have been made simple and convenient
in this case with the use of debugfs interface as user doesn't
need to shuffle between different files to execute one instruction
as was the case on using other alternatives.
Signed-off-by: Souradeep Chowdhury <[email protected]>
---
Documentation/ABI/testing/debugfs-driver-dcc | 124 +++
drivers/soc/qcom/Kconfig | 8 +
drivers/soc/qcom/Makefile | 1 +
drivers/soc/qcom/dcc.c | 1465 ++++++++++++++++++++++++++
4 files changed, 1598 insertions(+)
create mode 100644 Documentation/ABI/testing/debugfs-driver-dcc
create mode 100644 drivers/soc/qcom/dcc.c
diff --git a/Documentation/ABI/testing/debugfs-driver-dcc b/Documentation/ABI/testing/debugfs-driver-dcc
new file mode 100644
index 0000000..70029ab
--- /dev/null
+++ b/Documentation/ABI/testing/debugfs-driver-dcc
@@ -0,0 +1,124 @@
+What: /sys/kernel/debug/dcc/.../trigger
+Date: March 2022
+Contact: Souradeep Chowdhury <[email protected]>
+Description:
+ This is the debugfs interface for manual software
+ triggers. The user can simply enter a 1 against
+ the debugfs file and enable a manual trigger.
+ Example:
+ echo 1 > /sys/kernel/debug/dcc/.../trigger
+
+What: /sys/kernel/debug/dcc/.../enable
+Date: March 2022
+Contact: Souradeep Chowdhury <[email protected]>
+Description:
+ This debugfs interface is used for enabling the
+ the dcc hardware. On enabling the dcc, all the
+ addresses entered by the user is written into
+ dcc sram which is read by the dcc hardware on
+ manual or crash induced triggers.
+ Example:
+ echo 0 > /sys/bus/platform/devices/.../enable
+ (disable dcc)
+ echo 1 > /sys/bus/platform/devices/.../enable
+ (enable dcc)
+
+What: /sys/kernel/debug/dcc/.../config_read
+Date: March 2022
+Contact: Souradeep Chowdhury <[email protected]>
+Description:
+ This stores the addresses of the registers which
+ needs to be read in case of a hardware crash or
+ manual software triggers. The address entered here
+ are considered under read type instruction.
+ Example:
+ echo <1> <2> <3> >/sys/kernel/debug/dcc/../config_read
+ 1->Address to be considered for reading the value.
+ 2->The word count of the addresses, read n words
+ starting from address <1>.
+ 3->Can be a 1 or 0 which indicates if it is apb or ahb
+ bus respectively.
+
+What: /sys/kernel/debug/dcc/.../config_write
+Date: March 2022
+Contact: Souradeep Chowdhury <[email protected]>
+Description:
+ This file allows user to write a value to the register
+ address given as argument. The reason for this feature
+ of dcc is that for accessing certain registers it is
+ necessary to set some bits of some other register.
+ Example:
+ echo <1> <2> <3> > /sys/bus/platform/devices/.../config_write
+ 1->Address to be considered for writing the value.
+ 2->The value that needs to be written at the location.
+ 3->Can be a 1 or 0 which indicates if it is apb or ahb
+ bus respectively.
+
+What: /sys/kernel/debug/dcc/.../config_reset
+Date: March 2022
+Contact: Souradeep Chowdhury <[email protected]>
+Description:
+ This file is used to reset the configuration of
+ a dcc driver to the default configuration. This
+ means that all the previous addresses stored in
+ the driver gets removed and user needs to enter
+ the address values from the start.
+ Example:
+ echo 1 > /sys/bus/platform/devices/.../config_reset
+
+What: /sys/kernel/debug/dcc/.../config_loop
+Date: March 2022
+Contact: Souradeep Chowdhury <[email protected]>
+Description:
+ This file is used to enter the loop type addresses for
+ dcc. DCC hardware provides feature to loop among multiple
+ addresses. For debugging purposes register values need to
+ be captured repeatedly in a loop. On giving the loop count
+ as n, the value at address will be captured n times in a
+ loop. At most 8 loop addresses can be configured at once.
+ Example:
+ echo <1> <2> <3> > /sys/kernel/debug/dcc/../config_loop
+ 1->The loop count, the number of times the value of the
+ addresses will be captured.
+ 2->The address count, total number of addresses to be
+ entered in this instruction.
+ 3->The series of addresses to be entered separated by a
+ space like <addr1> <addr2>... and so on.
+
+What: /sys/kernel/debug/dcc/.../config_read_write
+Date: March 2022
+Contact: Souradeep Chowdhury <[email protected]>
+Description:
+ This file is used to read the value of the register
+ and then write the value given as an argument to the
+ register address. The address argument should be given
+ of the form <addr> <mask> <value>.For debugging purposes
+ sometimes we need to first read from a register and then
+ set some values to the register.
+ Example:
+ echo <1> <2> <3> > /sys/kernel/debug/dcc/.../config_read_write
+ 1->The address which needs to be considered for read then write.
+ 2->The value that needs to be written on the address.
+ 3->The mask of the value to be written.
+
+What: /sys/kernel/debug/dcc/.../ready
+Date: March 2022
+Contact Souradeep Chowdhury <[email protected]>
+Description:
+ This file is used to check the status of the dcc
+ hardware if it's ready to take the inputs. A 0
+ here indicates dcc is in a ready condition.
+ Example:
+ cat /sys/kernel/debug/dcc/.../ready
+
+What: /sys/kernel/debug/dcc/.../curr_list
+Date: March 2022
+Contact: Souradeep Chowdhury <[email protected]>
+Description:
+ This attribute is used to enter the linklist to be
+ used while appending addresses. The range of values
+ for this is advertised either by a register or is
+ predefined. Max value for this can be till 8.
+ Example:
+ echo 0 > /sys/kernel/debug/dcc/...curr_list
+
diff --git a/drivers/soc/qcom/Kconfig b/drivers/soc/qcom/Kconfig
index 79b568f..5101912 100644
--- a/drivers/soc/qcom/Kconfig
+++ b/drivers/soc/qcom/Kconfig
@@ -69,6 +69,14 @@ config QCOM_LLCC
SDM845. This provides interfaces to clients that use the LLCC.
Say yes here to enable LLCC slice driver.
+config QCOM_DCC
+ tristate "Qualcomm Technologies, Inc. Data Capture and Compare(DCC) engine driver"
+ depends on ARCH_QCOM || COMPILE_TEST
+ help
+ This option enables driver for Data Capture and Compare engine. DCC
+ driver provides interface to configure DCC block and read back
+ captured data from DCC's internal SRAM.
+
config QCOM_KRYO_L2_ACCESSORS
bool
depends on ARCH_QCOM && ARM64 || COMPILE_TEST
diff --git a/drivers/soc/qcom/Makefile b/drivers/soc/qcom/Makefile
index ad675a6..0aaf82b 100644
--- a/drivers/soc/qcom/Makefile
+++ b/drivers/soc/qcom/Makefile
@@ -4,6 +4,7 @@ obj-$(CONFIG_QCOM_AOSS_QMP) += qcom_aoss.o
obj-$(CONFIG_QCOM_GENI_SE) += qcom-geni-se.o
obj-$(CONFIG_QCOM_COMMAND_DB) += cmd-db.o
obj-$(CONFIG_QCOM_CPR) += cpr.o
+obj-$(CONFIG_QCOM_DCC) += dcc.o
obj-$(CONFIG_QCOM_GSBI) += qcom_gsbi.o
obj-$(CONFIG_QCOM_MDT_LOADER) += mdt_loader.o
obj-$(CONFIG_QCOM_OCMEM) += ocmem.o
diff --git a/drivers/soc/qcom/dcc.c b/drivers/soc/qcom/dcc.c
new file mode 100644
index 0000000..70452757
--- /dev/null
+++ b/drivers/soc/qcom/dcc.c
@@ -0,0 +1,1465 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (c) 2015-2021, The Linux Foundation. All rights reserved.
+ */
+
+#include <linux/bitfield.h>
+#include <linux/bitops.h>
+#include <linux/debugfs.h>
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include <linux/io.h>
+#include <linux/iopoll.h>
+#include <linux/miscdevice.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/of_device.h>
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include <linux/uaccess.h>
+
+#define STATUS_READY_TIMEOUT 5000
+
+#define DCC_SRAM_NODE "dcc_sram"
+
+/* DCC registers */
+#define DCC_HW_INFO 0x04
+#define DCC_LL_NUM_INFO 0x10
+#define DCC_STATUS 0x1C
+#define DCC_LL_LOCK(m) (0x34 + 0x80 * m)
+#define DCC_LL_CFG(m) (0x38 + 0x80 * m)
+#define DCC_LL_BASE(m) (0x3c + 0x80 * m)
+#define DCC_FD_BASE(m) (0x40 + 0x80 * m)
+#define DCC_LL_TIMEOUT(m) (0x44 + 0x80 * m)
+#define DCC_LL_INT_ENABLE(m) (0x4C + 0x80 * m)
+#define DCC_LL_INT_STATUS(m) (0x50 + 0x80 * m)
+#define DCC_LL_SW_TRIGGER(m) (0x60 + 0x80 * m)
+#define DCC_LL_BUS_ACCESS_STATUS(m) (0x64 + 0x80 * m)
+
+#define DCC_MAP_LEVEL1 0x18
+#define DCC_MAP_LEVEL2 0x34
+#define DCC_MAP_LEVEL3 0x4C
+
+#define DCC_MAP_OFFSET1 0x10
+#define DCC_MAP_OFFSET2 0x18
+#define DCC_MAP_OFFSET3 0x1C
+#define DCC_MAP_OFFSET4 0x8
+
+#define DCC_FIX_LOOP_OFFSET 16
+#define DCC_VER_INFO_BIT 9
+
+#define DCC_READ 0
+#define DCC_WRITE 1
+#define DCC_LOOP 2
+#define DCC_READ_WRITE 3
+
+#define MAX_DCC_OFFSET GENMASK(9, 2)
+#define MAX_DCC_LEN GENMASK(6, 0)
+#define MAX_LOOP_CNT GENMASK(7, 0)
+#define MAX_LOOP_ADDR 10
+
+#define DCC_ADDR_DESCRIPTOR 0x00
+#define DCC_ADDR_LIMIT 27
+#define DCC_ADDR_OFF_RANGE 8
+#define DCC_ADDR_RANGE GENMASK(31, 4)
+#define DCC_LOOP_DESCRIPTOR BIT(30)
+#define DCC_RD_MOD_WR_DESCRIPTOR BIT(31)
+#define DCC_LINK_DESCRIPTOR GENMASK(31, 30)
+#define DCC_STATUS_MASK GENMASK(1, 0)
+#define DCC_LOCK_MASK BIT(0)
+#define DCC_LOOP_OFFSET_MASK BIT(6)
+#define DCC_TRIGGER_MASK BIT(9)
+
+#define DCC_READ_IND 0x00
+#define DCC_WRITE_IND (BIT(28))
+
+#define DCC_AHB_IND 0x00
+#define DCC_APB_IND BIT(29)
+
+#define DCC_MAX_LINK_LIST 8
+#define DCC_INVALID_LINK_LIST GENMASK(7, 0)
+
+#define DCC_VER_MASK1 GENMASK(6, 0)
+#define DCC_VER_MASK2 GENMASK(5, 0)
+
+#define DCC_RD_MOD_WR_ADDR 0xC105E
+
+/*DCC debugfs directory*/
+static struct dentry *dcc_dbg;
+
+enum dcc_descriptor_type {
+ DCC_ADDR_TYPE,
+ DCC_LOOP_TYPE,
+ DCC_READ_WRITE_TYPE,
+ DCC_WRITE_TYPE
+};
+
+struct dcc_config_entry {
+ u32 base;
+ u32 offset;
+ u32 len;
+ u32 index;
+ u32 loop_cnt;
+ u32 write_val;
+ u32 mask;
+ bool apb_bus;
+ enum dcc_descriptor_type desc_type;
+ struct list_head list;
+};
+
+/**
+ * struct dcc_drvdata - configuration information related to a dcc device
+ * @base: Base Address of the dcc device
+ * @dev: The device attached to the driver data
+ * @mutex: Lock to protect access and manipulation of dcc_drvdata
+ * @ram_base: Base address for the SRAM dedicated for the dcc device
+ * @ram_offset: Offset to the SRAM dedicated for dcc device
+ * @mem_map_ver: Memory map version of DCC hardware
+ * @ram_cfg: Used for address limit calculation for dcc
+ * @ram_start: Starting address of DCC SRAM
+ * @sram_dev: Miscellaneous device equivalent of dcc SRAM
+ * @cfg_head: Points to the head of the linked list of addresses
+ * @dbg_dir: Points to the debugfs directory created for dcc.
+ * @nr_config: Stores the number of addresses currently configured for a linkedlist
+ * @nr_link_list: Total number of linkedlists supported by the DCC configuration
+ * @curr_list: The index of the current linklist with which the driver is working
+ * @loopoff: Loop offset bits range for the addresses
+ * @enable: This contains an array of linkedlist enable flags
+ * @interrupt_disable:Flag to enable/disable interrupts
+ */
+struct dcc_drvdata {
+ void __iomem *base;
+ struct device *dev;
+ struct mutex mutex;
+ void __iomem *ram_base;
+ size_t ram_size;
+ size_t ram_offset;
+ int mem_map_ver;
+ phys_addr_t ram_cfg;
+ phys_addr_t ram_start;
+ struct miscdevice sram_dev;
+ struct list_head *cfg_head;
+ struct dentry *dbg_dir;
+ size_t *nr_config;
+ size_t nr_link_list;
+ u8 curr_list;
+ u8 loopoff;
+ bool *enable;
+ bool interrupt_disable;
+};
+
+struct dcc_cfg_attr {
+ u32 addr;
+ u32 prev_addr;
+ u32 prev_off;
+ u32 link;
+ u32 sram_offset;
+};
+
+struct dcc_cfg_loop_attr {
+ u32 loop;
+ u32 loop_cnt;
+ u32 loop_len;
+ u32 loop_off;
+ bool loop_start;
+};
+
+static size_t dcc_offset_conv(struct dcc_drvdata *drvdata, size_t off)
+{
+ /* If the memory map version is 1, adjust the offset based on
+ * the dcc version mask. If the memory map version is 2
+ * adjust the offset if the dcc version mask is greater than
+ * map level 2.For other conditions, just return the offset.
+ */
+ if (drvdata->mem_map_ver == 1) {
+ if (FIELD_GET(DCC_VER_MASK1, off) >= DCC_MAP_LEVEL3)
+ return off - DCC_MAP_OFFSET3;
+ if (FIELD_GET(DCC_VER_MASK1, off) >= DCC_MAP_LEVEL2)
+ return off - DCC_MAP_OFFSET2;
+ else if (FIELD_GET(DCC_VER_MASK1, off) >= DCC_MAP_LEVEL1)
+ return off - DCC_MAP_OFFSET1;
+ } else if (drvdata->mem_map_ver == 2) {
+ if (FIELD_GET(DCC_VER_MASK1, off) >= DCC_MAP_LEVEL2)
+ return off - DCC_MAP_OFFSET4;
+ }
+
+ return off;
+}
+
+static inline void dcc_writel(struct dcc_drvdata *drvdata,
+ u32 val, u32 off)
+{
+ writel((val), drvdata->base + dcc_offset_conv(drvdata, off));
+}
+
+static inline u32 dcc_readl(struct dcc_drvdata *drvdata, u32 off)
+{
+ return readl(drvdata->base + dcc_offset_conv(drvdata, off));
+}
+
+static void dcc_sram_writel(struct dcc_drvdata *drvdata,
+ u32 val, u32 *off)
+{
+ writel(val, drvdata->ram_base + *off);
+
+ *off += 4;
+}
+
+static int dcc_read_and_clear(struct dcc_drvdata *drvdata)
+{
+ int i;
+ u32 bus_status;
+ u32 ll_cfg;
+ u32 tmp_ll_cfg;
+
+ for (i = 0; i < drvdata->nr_link_list; i++) {
+ if (!drvdata->enable[i])
+ continue;
+
+ bus_status = dcc_readl(drvdata, DCC_LL_BUS_ACCESS_STATUS(i));
+ if (bus_status) {
+ dev_err(drvdata->dev,
+ "Read access error for list %d err: 0x%x.\n",
+ i, bus_status);
+
+ ll_cfg = dcc_readl(drvdata, DCC_LL_CFG(i));
+ tmp_ll_cfg = ll_cfg & ~DCC_TRIGGER_MASK;
+ dcc_writel(drvdata, tmp_ll_cfg, DCC_LL_CFG(i));
+ dcc_writel(drvdata, DCC_STATUS_MASK,
+ DCC_LL_BUS_ACCESS_STATUS(i));
+ dcc_writel(drvdata, ll_cfg, DCC_LL_CFG(i));
+ return -ENODATA;
+ }
+ }
+
+ return 0;
+}
+
+static int dcc_sw_trigger(struct dcc_drvdata *drvdata)
+{
+ int ret;
+ int i;
+ u32 ll_cfg;
+ u32 tmp_ll_cfg;
+ u32 val;
+
+ mutex_lock(&drvdata->mutex);
+
+ for (i = 0; i < drvdata->nr_link_list; i++) {
+ if (!drvdata->enable[i])
+ continue;
+ ll_cfg = dcc_readl(drvdata, DCC_LL_CFG(i));
+ tmp_ll_cfg = ll_cfg & ~DCC_TRIGGER_MASK;
+ dcc_writel(drvdata, tmp_ll_cfg, DCC_LL_CFG(i));
+ dcc_writel(drvdata, 1, DCC_LL_SW_TRIGGER(i));
+ dcc_writel(drvdata, ll_cfg, DCC_LL_CFG(i));
+ }
+
+ if (readl_poll_timeout((drvdata->base + dcc_offset_conv(drvdata, DCC_STATUS)),
+ val, (FIELD_GET(DCC_STATUS_MASK, val) == 0), 1, STATUS_READY_TIMEOUT)) {
+ dev_err(drvdata->dev,
+ "DCC is busy after receiving sw tigger.\n");
+ ret = -EBUSY;
+ goto err;
+ }
+
+ ret = dcc_read_and_clear(drvdata);
+
+err:
+ mutex_unlock(&drvdata->mutex);
+ return ret;
+}
+
+static void _dcc_ll_cfg_reset_link(struct dcc_cfg_attr *cfg)
+{
+ cfg->addr = 0x00;
+ cfg->link = 0;
+ cfg->prev_off = 0;
+ cfg->prev_addr = cfg->addr;
+}
+
+static void _dcc_emit_read_write(struct dcc_drvdata *drvdata,
+ struct dcc_config_entry *entry,
+ struct dcc_cfg_attr *cfg)
+{
+ if (cfg->link) {
+ /*
+ * write new offset = 1 to continue
+ * processing the list
+ */
+
+ dcc_sram_writel(drvdata, cfg->link, &cfg->sram_offset);
+
+ /* Reset link and prev_off */
+ _dcc_ll_cfg_reset_link(cfg);
+ }
+
+ cfg->addr = DCC_RD_MOD_WR_DESCRIPTOR;
+ dcc_sram_writel(drvdata, cfg->addr, &cfg->sram_offset);
+
+ dcc_sram_writel(drvdata, entry->mask, &cfg->sram_offset);
+
+ dcc_sram_writel(drvdata, entry->write_val, &cfg->sram_offset);
+
+ cfg->addr = 0;
+}
+
+static void _dcc_emit_loop(struct dcc_drvdata *drvdata, struct dcc_config_entry *entry,
+ struct dcc_cfg_attr *cfg,
+ struct dcc_cfg_loop_attr *cfg_loop,
+ u32 *total_len)
+{
+ /* Check if we need to write link of prev entry */
+ if (cfg->link)
+ dcc_sram_writel(drvdata, cfg->link, &cfg->sram_offset);
+
+ if (cfg_loop->loop_start) {
+ cfg_loop->loop = (cfg->sram_offset - cfg_loop->loop_off) / 4;
+ cfg_loop->loop |= (cfg_loop->loop_cnt << drvdata->loopoff) &
+ GENMASK(DCC_ADDR_LIMIT, drvdata->loopoff);
+ cfg_loop->loop |= DCC_LOOP_DESCRIPTOR;
+ *total_len += (*total_len - cfg_loop->loop_len) * cfg_loop->loop_cnt;
+
+ dcc_sram_writel(drvdata, cfg_loop->loop, &cfg->sram_offset);
+
+ cfg_loop->loop_start = false;
+ cfg_loop->loop_len = 0;
+ cfg_loop->loop_off = 0;
+ } else {
+ cfg_loop->loop_start = true;
+ cfg_loop->loop_cnt = entry->loop_cnt - 1;
+ cfg_loop->loop_len = *total_len;
+ cfg_loop->loop_off = cfg->sram_offset;
+ }
+
+ /* Reset link and prev_off */
+ _dcc_ll_cfg_reset_link(cfg);
+}
+
+static void _dcc_emit_write(struct dcc_drvdata *drvdata,
+ struct dcc_config_entry *entry,
+ struct dcc_cfg_attr *cfg,
+ u32 *total_len)
+{
+ u32 off;
+
+ if (cfg->link) {
+ /*
+ * write new offset = 1 to continue
+ * processing the list
+ */
+ dcc_sram_writel(drvdata, cfg->link, &cfg->sram_offset);
+
+ /* Reset link and prev_off */
+ cfg->addr = 0x00;
+ cfg->prev_off = 0;
+ cfg->prev_addr = cfg->addr;
+ }
+
+ off = entry->offset/4;
+ /* write new offset-length pair to correct position */
+ cfg->link |= ((off & GENMASK(7, 0)) | BIT(15) | ((entry->len << 8) & GENMASK(14, 8)));
+ cfg->link |= DCC_LINK_DESCRIPTOR;
+
+ /* Address type */
+ cfg->addr = (entry->base >> 4) & GENMASK(DCC_ADDR_LIMIT, 0);
+ if (entry->apb_bus)
+ cfg->addr |= DCC_ADDR_DESCRIPTOR | DCC_WRITE_IND | DCC_APB_IND;
+ else
+ cfg->addr |= DCC_ADDR_DESCRIPTOR | DCC_WRITE_IND | DCC_AHB_IND;
+ dcc_sram_writel(drvdata, cfg->addr, &cfg->sram_offset);
+
+ dcc_sram_writel(drvdata, cfg->link, &cfg->sram_offset);
+
+ dcc_sram_writel(drvdata, entry->write_val, &cfg->sram_offset);
+
+ cfg->addr = 0x00;
+ cfg->link = 0;
+}
+
+static int _dcc_emit_read(struct dcc_drvdata *drvdata,
+ struct dcc_config_entry *entry,
+ struct dcc_cfg_attr *cfg,
+ u32 *pos, u32 *total_len)
+{
+ int ret = 0;
+ u32 off;
+ u32 temp_off;
+
+ cfg->addr = (entry->base >> 4) & GENMASK(27, 0);
+
+ if (entry->apb_bus)
+ cfg->addr |= DCC_ADDR_DESCRIPTOR | DCC_READ_IND | DCC_APB_IND;
+ else
+ cfg->addr |= DCC_ADDR_DESCRIPTOR | DCC_READ_IND | DCC_AHB_IND;
+
+ off = entry->offset/4;
+
+ *total_len += entry->len * 4;
+
+ if (!cfg->prev_addr || cfg->prev_addr != cfg->addr || cfg->prev_off > off) {
+ /* Check if we need to write prev link entry */
+ if (cfg->link)
+ dcc_sram_writel(drvdata, cfg->link, &cfg->sram_offset);
+ dev_dbg(drvdata->dev, "DCC: sram address 0x%x\n", cfg->sram_offset);
+
+ /* Write address */
+ dcc_sram_writel(drvdata, cfg->addr, &cfg->sram_offset);
+
+ /* Reset link and prev_off */
+ cfg->link = 0;
+ cfg->prev_off = 0;
+ }
+
+ if ((off - cfg->prev_off) > 0xFF || entry->len > MAX_DCC_LEN) {
+ dev_err(drvdata->dev, "DCC: Programming error Base: 0x%x, offset 0x%x\n",
+ entry->base, entry->offset);
+ ret = -EINVAL;
+ return ret;
+ }
+
+ if (cfg->link) {
+ /*
+ * link already has one offset-length so new
+ * offset-length needs to be placed at
+ * bits [29:15]
+ */
+ *pos = 15;
+
+ /* Clear bits [31:16] */
+ cfg->link &= GENMASK(14, 0);
+ } else {
+ /*
+ * link is empty, so new offset-length needs
+ * to be placed at bits [15:0]
+ */
+ *pos = 0;
+ cfg->link = 1 << 15;
+ }
+
+ /* write new offset-length pair to correct position */
+ temp_off = (off-cfg->prev_off) & GENMASK(7, 0);
+ cfg->link |= temp_off |((entry->len << 8) & GENMASK(14, 8)) << *pos;
+
+ cfg->link |= DCC_LINK_DESCRIPTOR;
+
+ if (*pos) {
+ dcc_sram_writel(drvdata, cfg->link, &cfg->sram_offset);
+ cfg->link = 0;
+ }
+
+ cfg->prev_off = off + entry->len - 1;
+ cfg->prev_addr = cfg->addr;
+ return ret;
+}
+
+static int __dcc_emit_config(struct dcc_drvdata *drvdata, int curr_list)
+{
+ int ret;
+ u32 total_len, pos;
+ struct dcc_config_entry *entry;
+ struct dcc_cfg_attr cfg;
+ struct dcc_cfg_loop_attr cfg_loop;
+
+ memset(&cfg, 0, sizeof(cfg));
+ memset(&cfg_loop, 0, sizeof(cfg_loop));
+ cfg.sram_offset = drvdata->ram_cfg * 4;
+ total_len = 0;
+
+ list_for_each_entry(entry, &drvdata->cfg_head[curr_list], list) {
+ switch (entry->desc_type) {
+ case DCC_READ_WRITE_TYPE:
+ _dcc_emit_read_write(drvdata, entry, &cfg);
+ break;
+
+ case DCC_LOOP_TYPE:
+ _dcc_emit_loop(drvdata, entry, &cfg, &cfg_loop, &total_len);
+ break;
+
+ case DCC_WRITE_TYPE:
+ _dcc_emit_write(drvdata, entry, &cfg, &total_len);
+ break;
+
+ case DCC_ADDR_TYPE:
+ ret = _dcc_emit_read(drvdata, entry, &cfg, &pos, &total_len);
+ if (ret)
+ goto overstep;
+ break;
+ }
+ }
+
+ if (cfg.link)
+ dcc_sram_writel(drvdata, cfg.link, &cfg.sram_offset);
+
+ if (cfg_loop.loop_start) {
+ dev_err(drvdata->dev, "DCC: Programming error: Loop unterminated\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
+ /* Handling special case of list ending with a rd_mod_wr */
+ if (cfg.addr == DCC_RD_MOD_WR_DESCRIPTOR) {
+ cfg.addr = (DCC_RD_MOD_WR_ADDR) & GENMASK(27, 0);
+ cfg.addr |= DCC_ADDR_DESCRIPTOR;
+ dcc_sram_writel(drvdata, cfg.addr, &cfg.sram_offset);
+ }
+
+ /* Setting zero to indicate end of the list */
+ cfg.link = DCC_LINK_DESCRIPTOR;
+ dcc_sram_writel(drvdata, cfg.link, &cfg.sram_offset);
+
+ /*Check if sram offset exceeds the ram size*/
+ if (cfg.sram_offset > drvdata->ram_size)
+ goto overstep;
+
+ /* Update ram_cfg and check if the data will overstep */
+ drvdata->ram_cfg = (cfg.sram_offset + total_len) / 4;
+
+ if (cfg.sram_offset + total_len > drvdata->ram_size) {
+ cfg.sram_offset += total_len;
+ goto overstep;
+ }
+
+ drvdata->ram_start = cfg.sram_offset/4;
+ return 0;
+overstep:
+ ret = -EINVAL;
+ memset_io(drvdata->ram_base, 0, drvdata->ram_size);
+
+err:
+ return ret;
+}
+
+static int dcc_valid_list(struct dcc_drvdata *drvdata, int curr_list)
+{
+ u32 lock_reg;
+
+ if (list_empty(&drvdata->cfg_head[curr_list]))
+ return -EINVAL;
+
+ if (drvdata->enable[curr_list]) {
+ dev_err(drvdata->dev, "List %d is already enabled\n",
+ curr_list);
+ return -EINVAL;
+ }
+
+ lock_reg = dcc_readl(drvdata, DCC_LL_LOCK(curr_list));
+ if (lock_reg & 0x1) {
+ dev_err(drvdata->dev, "List %d is already locked\n",
+ curr_list);
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static bool is_dcc_enabled(struct dcc_drvdata *drvdata)
+{
+ bool dcc_enable = false;
+ int list;
+
+ for (list = 0; list < DCC_MAX_LINK_LIST; list++) {
+ if (drvdata->enable[list]) {
+ dcc_enable = true;
+ break;
+ }
+ }
+
+ return dcc_enable;
+}
+
+static int dcc_enable(struct dcc_drvdata *drvdata)
+{
+ int ret;
+ int list;
+ u32 ram_cfg_base;
+
+ mutex_lock(&drvdata->mutex);
+
+ if (!is_dcc_enabled(drvdata)) {
+ memset_io(drvdata->ram_base,
+ 0xde, drvdata->ram_size);
+ }
+
+ for (list = 0; list < drvdata->nr_link_list; list++) {
+ if (dcc_valid_list(drvdata, list))
+ continue;
+
+ /* 1. Take ownership of the list */
+ dcc_writel(drvdata, DCC_LOCK_MASK, DCC_LL_LOCK(list));
+
+ /* 2. Program linked-list in the SRAM */
+ ram_cfg_base = drvdata->ram_cfg;
+ ret = __dcc_emit_config(drvdata, list);
+ if (ret) {
+ dcc_writel(drvdata, 0, DCC_LL_LOCK(list));
+ goto err;
+ }
+
+ /* 3. program DCC_RAM_CFG reg */
+ dcc_writel(drvdata, ram_cfg_base +
+ drvdata->ram_offset/4, DCC_LL_BASE(list));
+ dcc_writel(drvdata, drvdata->ram_start +
+ drvdata->ram_offset/4, DCC_FD_BASE(list));
+ dcc_writel(drvdata, 0xFFF, DCC_LL_TIMEOUT(list));
+
+ /* 4. Clears interrupt status register */
+ dcc_writel(drvdata, 0, DCC_LL_INT_ENABLE(list));
+ dcc_writel(drvdata, (BIT(0) | BIT(1) | BIT(2)),
+ DCC_LL_INT_STATUS(list));
+
+ drvdata->enable[list] = true;
+
+ /* 5. Configure trigger */
+ dcc_writel(drvdata, DCC_TRIGGER_MASK, DCC_LL_CFG(list));
+ }
+
+err:
+ mutex_unlock(&drvdata->mutex);
+ return ret;
+}
+
+static void dcc_disable(struct dcc_drvdata *drvdata)
+{
+ int curr_list;
+
+ mutex_lock(&drvdata->mutex);
+
+ for (curr_list = 0; curr_list < drvdata->nr_link_list; curr_list++) {
+ if (!drvdata->enable[curr_list])
+ continue;
+ dcc_writel(drvdata, 0, DCC_LL_CFG(curr_list));
+ dcc_writel(drvdata, 0, DCC_LL_BASE(curr_list));
+ dcc_writel(drvdata, 0, DCC_FD_BASE(curr_list));
+ dcc_writel(drvdata, 0, DCC_LL_LOCK(curr_list));
+ drvdata->enable[curr_list] = false;
+ }
+ memset_io(drvdata->ram_base, 0, drvdata->ram_size);
+ drvdata->ram_cfg = 0;
+ drvdata->ram_start = 0;
+ mutex_unlock(&drvdata->mutex);
+}
+
+static ssize_t curr_list_read(struct file *filp, char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ int ret;
+ char buf[20];
+ struct dcc_drvdata *drvdata = filp->private_data;
+
+ mutex_lock(&drvdata->mutex);
+ if (drvdata->curr_list == DCC_INVALID_LINK_LIST) {
+ dev_err(drvdata->dev, "curr_list is not set.\n");
+ ret = -EINVAL;
+ return ret;
+ }
+
+ ret = scnprintf(buf, PAGE_SIZE, "%d\n", drvdata->curr_list);
+ mutex_unlock(&drvdata->mutex);
+
+ return simple_read_from_buffer(userbuf, count, ppos, buf, ret);
+}
+
+static ssize_t curr_list_write(struct file *filp,
+ const char __user *user_buf, size_t count,
+ loff_t *ppos)
+{
+ struct dcc_drvdata *drvdata = filp->private_data;
+ int ret;
+ unsigned int val;
+ u32 lock_reg;
+ bool dcc_enable = false;
+
+ ret = kstrtouint_from_user(user_buf, count, 0, &val);
+ if (ret)
+ return ret;
+
+ if (val >= drvdata->nr_link_list)
+ return -EINVAL;
+
+ mutex_lock(&drvdata->mutex);
+
+ dcc_enable = is_dcc_enabled(drvdata);
+ if (drvdata->curr_list != DCC_INVALID_LINK_LIST && dcc_enable) {
+ dev_err(drvdata->dev, "DCC is enabled, please disable it first.\n");
+ mutex_unlock(&drvdata->mutex);
+ return -EINVAL;
+ }
+
+ lock_reg = dcc_readl(drvdata, DCC_LL_LOCK(val));
+ if (lock_reg & 0x1) {
+ dev_err(drvdata->dev, "DCC linked list is already configured\n");
+ mutex_unlock(&drvdata->mutex);
+ return -EINVAL;
+ }
+ drvdata->curr_list = val;
+ mutex_unlock(&drvdata->mutex);
+
+ return count;
+}
+
+static const struct file_operations curr_list_fops = {
+ .read = curr_list_read,
+ .write = curr_list_write,
+ .open = simple_open,
+ .llseek = generic_file_llseek,
+};
+
+static ssize_t trigger_write(struct file *filp,
+ const char __user *user_buf, size_t count,
+ loff_t *ppos)
+{
+ int ret = 0;
+ unsigned int val;
+ struct dcc_drvdata *drvdata = filp->private_data;
+
+ ret = kstrtouint_from_user(user_buf, count, 0, &val);
+ if (ret < 0)
+ return ret;
+
+ if (val != 1)
+ return -EINVAL;
+
+ ret = dcc_sw_trigger(drvdata);
+ if (!ret)
+ ret = count;
+
+ return ret;
+}
+
+static const struct file_operations trigger_fops = {
+ .write = trigger_write,
+ .open = simple_open,
+ .llseek = generic_file_llseek,
+};
+
+static ssize_t enable_read(struct file *filp, char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ int ret;
+ bool dcc_enable = false;
+ char buf[20];
+ struct dcc_drvdata *drvdata = filp->private_data;
+
+ mutex_lock(&drvdata->mutex);
+ if (drvdata->curr_list >= drvdata->nr_link_list) {
+ dev_err(drvdata->dev, "Select link list to program using curr_list\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
+ dcc_enable = is_dcc_enabled(drvdata);
+
+ ret = scnprintf(buf, PAGE_SIZE, "%u\n",
+ (unsigned int)dcc_enable);
+err:
+ mutex_unlock(&drvdata->mutex);
+ if (ret > 0)
+ return simple_read_from_buffer(userbuf, count, ppos, buf, ret);
+ else
+ return ret;
+}
+
+static ssize_t enable_write(struct file *filp, const char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ int ret = 0;
+ unsigned int val;
+ struct dcc_drvdata *drvdata = filp->private_data;
+
+ ret = kstrtouint_from_user(userbuf, count, 0, &val);
+ if (ret < 0)
+ return ret;
+
+ if (val)
+ ret = dcc_enable(drvdata);
+ else
+ dcc_disable(drvdata);
+
+ if (!ret)
+ ret = count;
+
+ return ret;
+
+}
+
+static const struct file_operations enable_fops = {
+ .read = enable_read,
+ .write = enable_write,
+ .open = simple_open,
+ .llseek = generic_file_llseek,
+};
+
+static ssize_t config_read(struct file *filp, char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ struct dcc_drvdata *drvdata = filp->private_data;
+ struct dcc_config_entry *entry;
+ char local_buf[64];
+ int len = 0, tot_len = 0;
+
+ mutex_lock(&drvdata->mutex);
+ if (drvdata->curr_list >= drvdata->nr_link_list) {
+ dev_err(drvdata->dev, "Select link list to program using curr_list\n");
+ tot_len = -EINVAL;
+ goto err;
+ }
+
+ list_for_each_entry(entry,
+ &drvdata->cfg_head[drvdata->curr_list], list) {
+ switch (entry->desc_type) {
+ case DCC_READ_WRITE_TYPE:
+ len = snprintf(local_buf, 64, "Index: 0x%x, mask: 0x%x, val: 0x%x\n",
+ entry->index, entry->mask, entry->write_val);
+ break;
+ case DCC_LOOP_TYPE:
+ len = snprintf(local_buf, 64, "Index: 0x%x, Loop: %d\n",
+ entry->index, entry->loop_cnt);
+ break;
+ case DCC_WRITE_TYPE:
+ len = snprintf(local_buf, 64,
+ "Write Index: 0x%x, Base: 0x%x, Offset: 0x%x, len: 0x%x APB: %d\n",
+ entry->index, entry->base, entry->offset, entry->len,
+ entry->apb_bus);
+ break;
+ case DCC_ADDR_TYPE:
+ len = snprintf(local_buf, 64,
+ "Read Index: 0x%x, Base: 0x%x, Offset: 0x%x, len: 0x%x APB: %d\n",
+ entry->index, entry->base, entry->offset,
+ entry->len, entry->apb_bus);
+ }
+
+ if ((count + len) > PAGE_SIZE) {
+ dev_err(drvdata->dev, "DCC: Couldn't write complete config\n");
+ break;
+ }
+ tot_len += len;
+ simple_read_from_buffer(userbuf, count, ppos, local_buf, len);
+ }
+
+err:
+ mutex_unlock(&drvdata->mutex);
+ return tot_len;
+
+}
+
+static int dcc_config_add(struct dcc_drvdata *drvdata, unsigned int addr,
+ unsigned int len, int apb_bus)
+{
+ int ret = 0;
+ struct dcc_config_entry *entry, *pentry;
+ unsigned int base, offset;
+
+ mutex_lock(&drvdata->mutex);
+
+ if (drvdata->curr_list >= drvdata->nr_link_list) {
+ dev_err(drvdata->dev, "Select link list to program using curr_list\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
+ if (!len || len > (drvdata->ram_size / DCC_ADDR_OFF_RANGE)) {
+ dev_err(drvdata->dev, "DCC: Invalid length\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
+ base = addr & DCC_ADDR_RANGE;
+
+ if (!list_empty(&drvdata->cfg_head[drvdata->curr_list])) {
+ pentry = list_last_entry(&drvdata->cfg_head[drvdata->curr_list],
+ struct dcc_config_entry, list);
+
+ if (pentry->desc_type == DCC_ADDR_TYPE &&
+ addr >= (pentry->base + pentry->offset) &&
+ addr <= (pentry->base +
+ pentry->offset + MAX_DCC_OFFSET)) {
+
+ /* Re-use base address from last entry */
+ base = pentry->base;
+
+ if ((pentry->len * 4 + pentry->base + pentry->offset)
+ == addr) {
+ len += pentry->len;
+
+ if (len > MAX_DCC_LEN)
+ pentry->len = MAX_DCC_LEN;
+ else
+ pentry->len = len;
+
+ addr = pentry->base + pentry->offset +
+ pentry->len * 4;
+ len -= pentry->len;
+ }
+ }
+ }
+
+ offset = addr - base;
+
+ while (len) {
+ entry = devm_kzalloc(drvdata->dev, sizeof(*entry), GFP_KERNEL);
+ if (!entry) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ entry->base = base;
+ entry->offset = offset;
+ entry->len = min_t(u32, len, MAX_DCC_LEN);
+ entry->index = drvdata->nr_config[drvdata->curr_list]++;
+ entry->desc_type = DCC_ADDR_TYPE;
+ entry->apb_bus = apb_bus;
+ INIT_LIST_HEAD(&entry->list);
+ list_add_tail(&entry->list,
+ &drvdata->cfg_head[drvdata->curr_list]);
+
+ len -= entry->len;
+ offset += MAX_DCC_LEN * 4;
+ }
+
+err:
+ mutex_unlock(&drvdata->mutex);
+ return ret;
+}
+
+static ssize_t config_write(struct file *filp,
+ const char __user *user_buf, size_t count,
+ loff_t *ppos)
+{
+ int ret, len, apb_bus;
+ unsigned int base;
+ char buf[20];
+ struct dcc_drvdata *drvdata = filp->private_data;
+ int nval;
+
+ ret = copy_from_user(buf, user_buf, count);
+ if (ret)
+ return -EFAULT;
+
+ nval = sscanf(buf, "%x %i %d", &base, &len, &apb_bus);
+ if (nval <= 0 || nval > 3)
+ return -EINVAL;
+
+ if (nval == 1) {
+ len = 1;
+ apb_bus = 0;
+ } else if (nval == 2) {
+ apb_bus = 0;
+ } else {
+ apb_bus = 1;
+ }
+
+ ret = dcc_config_add(drvdata, base, len, apb_bus);
+ if (ret)
+ return ret;
+
+ return count;
+
+}
+
+static const struct file_operations config_fops = {
+ .read = config_read,
+ .write = config_write,
+ .open = simple_open,
+ .llseek = generic_file_llseek,
+};
+
+static void dcc_config_reset(struct dcc_drvdata *drvdata)
+{
+ struct dcc_config_entry *entry, *temp;
+ int curr_list;
+
+ mutex_lock(&drvdata->mutex);
+
+ for (curr_list = 0; curr_list < drvdata->nr_link_list; curr_list++) {
+ list_for_each_entry_safe(entry, temp,
+ &drvdata->cfg_head[curr_list], list) {
+ list_del(&entry->list);
+ devm_kfree(drvdata->dev, entry);
+ drvdata->nr_config[curr_list]--;
+ }
+ }
+ drvdata->ram_start = 0;
+ drvdata->ram_cfg = 0;
+ mutex_unlock(&drvdata->mutex);
+}
+
+static ssize_t config_reset_write(struct file *filp,
+ const char __user *user_buf, size_t count,
+ loff_t *ppos)
+{
+ unsigned int val, ret;
+ struct dcc_drvdata *drvdata = filp->private_data;
+
+ ret = kstrtouint_from_user(user_buf, count, 0, &val);
+ if (ret < 0)
+ return ret;
+
+ if (val)
+ dcc_config_reset(drvdata);
+
+ return count;
+}
+
+static const struct file_operations config_reset_fops = {
+ .write = config_reset_write,
+ .open = simple_open,
+ .llseek = generic_file_llseek,
+};
+
+static ssize_t ready_read(struct file *filp, char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ int ret;
+ char buf[20];
+ struct dcc_drvdata *drvdata = filp->private_data;
+
+ mutex_lock(&drvdata->mutex);
+
+ if (drvdata->curr_list >= drvdata->nr_link_list) {
+ dev_err(drvdata->dev, "Select link list to program using curr_list\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
+ if (!drvdata->enable[drvdata->curr_list]) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ ret = scnprintf(buf, PAGE_SIZE, "%u\n",
+ (unsigned int)FIELD_GET(BIT(1), dcc_readl(drvdata, DCC_STATUS)));
+err:
+ mutex_unlock(&drvdata->mutex);
+
+ if (ret > 0)
+ return simple_read_from_buffer(userbuf, count, ppos, buf, ret);
+ else
+ return ret;
+}
+
+static const struct file_operations ready_fops = {
+ .read = ready_read,
+ .open = simple_open,
+ .llseek = generic_file_llseek,
+};
+
+static int dcc_add_loop(struct dcc_drvdata *drvdata, unsigned long loop_cnt)
+{
+ struct dcc_config_entry *entry;
+
+ entry = devm_kzalloc(drvdata->dev, sizeof(*entry), GFP_KERNEL);
+ if (!entry)
+ return -ENOMEM;
+
+ entry->loop_cnt = min_t(u32, loop_cnt, MAX_LOOP_CNT);
+ entry->index = drvdata->nr_config[drvdata->curr_list]++;
+ entry->desc_type = DCC_LOOP_TYPE;
+ INIT_LIST_HEAD(&entry->list);
+ list_add_tail(&entry->list, &drvdata->cfg_head[drvdata->curr_list]);
+
+ return 0;
+}
+
+static ssize_t loop_write(struct file *filp, const char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ int ret, cnt = 2, i = 0;
+ char *token, *input, buf[80];
+ char delim[2] = " ";
+ unsigned int val[MAX_LOOP_ADDR];
+ struct dcc_drvdata *drvdata = filp->private_data;
+
+ input = buf;
+
+ if (drvdata->curr_list >= drvdata->nr_link_list) {
+ dev_err(drvdata->dev, "Select link list to program using curr_list\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
+ ret = copy_from_user(buf, userbuf, count);
+ if (ret)
+ return -EFAULT;
+
+ if (input[count - 1] == '\n')
+ input[count - 1] = '\0';
+
+ token = strsep(&input, delim);
+ while (token != NULL) {
+ ret = kstrtoint(token, 0, &val[i++]);
+ if (ret)
+ goto err;
+
+ token = strsep(&input, delim);
+ }
+
+ ret = dcc_add_loop(drvdata, val[0]);
+ if (ret)
+ goto err;
+
+ for (i = 0; i < val[1]; i++)
+ dcc_config_add(drvdata, val[cnt++], 1, 0);
+
+ ret = dcc_add_loop(drvdata, 1);
+ if (ret)
+ goto err;
+ ret = count;
+err:
+ return ret;
+}
+
+static const struct file_operations loop_fops = {
+ .write = loop_write,
+ .open = simple_open,
+ .llseek = generic_file_llseek,
+};
+
+static int dcc_rd_mod_wr_add(struct dcc_drvdata *drvdata, unsigned int mask,
+ unsigned int val)
+{
+ int ret = 0;
+ struct dcc_config_entry *entry;
+
+ mutex_lock(&drvdata->mutex);
+
+ if (drvdata->curr_list >= drvdata->nr_link_list) {
+ dev_err(drvdata->dev, "Select link list to program using curr_list\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
+ if (list_empty(&drvdata->cfg_head[drvdata->curr_list])) {
+ dev_err(drvdata->dev, "DCC: No read address programmed\n");
+ ret = -EPERM;
+ goto err;
+ }
+
+ entry = devm_kzalloc(drvdata->dev, sizeof(*entry), GFP_KERNEL);
+ if (!entry) {
+ ret = -ENOMEM;
+ goto err;
+ }
+
+ entry->desc_type = DCC_READ_WRITE_TYPE;
+ entry->mask = mask;
+ entry->write_val = val;
+ entry->index = drvdata->nr_config[drvdata->curr_list]++;
+ INIT_LIST_HEAD(&entry->list);
+ list_add_tail(&entry->list, &drvdata->cfg_head[drvdata->curr_list]);
+err:
+ mutex_unlock(&drvdata->mutex);
+ return ret;
+}
+
+static ssize_t rd_mod_wr_write(struct file *filp, const char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ int ret;
+ int nval;
+ char buf[20];
+ unsigned int addr, mask, val;
+ struct dcc_drvdata *drvdata = filp->private_data;
+
+ ret = copy_from_user(buf, userbuf, count);
+ if (ret)
+ return -EFAULT;
+
+ nval = sscanf(buf, "%x %x %x", &addr, &mask, &val);
+
+ if (nval <= 1 || nval > 3)
+ return -EINVAL;
+
+ ret = dcc_config_add(drvdata, addr, 1, 0);
+ if (ret)
+ return ret;
+
+ ret = dcc_rd_mod_wr_add(drvdata, mask, val);
+ if (ret)
+ return ret;
+
+ return count;
+
+}
+
+static const struct file_operations rd_mod_wr_fops = {
+ .write = rd_mod_wr_write,
+ .open = simple_open,
+ .llseek = generic_file_llseek,
+};
+
+static int dcc_add_write(struct dcc_drvdata *drvdata, unsigned int addr,
+ unsigned int write_val, int apb_bus)
+{
+ struct dcc_config_entry *entry;
+
+ entry = devm_kzalloc(drvdata->dev, sizeof(*entry), GFP_KERNEL);
+ if (!entry)
+ return -ENOMEM;
+
+ entry->desc_type = DCC_WRITE_TYPE;
+ entry->base = addr & GENMASK(31, 4);
+ entry->offset = addr - entry->base;
+ entry->write_val = write_val;
+ entry->index = drvdata->nr_config[drvdata->curr_list]++;
+ entry->len = 1;
+ entry->apb_bus = apb_bus;
+ INIT_LIST_HEAD(&entry->list);
+ list_add_tail(&entry->list, &drvdata->cfg_head[drvdata->curr_list]);
+
+ return 0;
+}
+
+static ssize_t config_wr_write(struct file *filp, const char __user *userbuf,
+ size_t count, loff_t *ppos)
+{
+ int ret;
+ int nval;
+ char buf[20];
+ unsigned int addr, write_val;
+ int apb_bus = 0;
+ struct dcc_drvdata *drvdata = filp->private_data;
+
+ ret = copy_from_user(buf, userbuf, count);
+ if (ret)
+ return -EFAULT;
+
+ mutex_lock(&drvdata->mutex);
+
+ nval = sscanf(buf, "%x %x %d", &addr, &write_val, &apb_bus);
+
+ if (nval <= 1 || nval > 3) {
+ ret = -EINVAL;
+ goto err;
+ }
+
+ if (drvdata->curr_list >= drvdata->nr_link_list) {
+ dev_err(drvdata->dev, "Select link list to program using curr_list\n");
+ ret = -EINVAL;
+ goto err;
+ }
+
+ if (nval == 3 && apb_bus != 0)
+ apb_bus = 1;
+
+ ret = dcc_add_write(drvdata, addr, write_val, apb_bus);
+ if (ret)
+ goto err;
+
+ ret = count;
+err:
+ mutex_unlock(&drvdata->mutex);
+ return ret;
+}
+
+static const struct file_operations config_wr_fops = {
+ .write = config_wr_write,
+ .open = simple_open,
+ .llseek = generic_file_llseek,
+};
+
+void dcc_delete_debug_dir(struct dcc_drvdata *dcc)
+{
+ debugfs_remove_recursive(dcc->dbg_dir);
+};
+
+void dcc_create_debug_dir(struct dcc_drvdata *dcc)
+{
+ struct device *dev = dcc->dev;
+
+ if (debugfs_initialized()) {
+ dcc_dbg = debugfs_create_dir(KBUILD_MODNAME, NULL);
+ if (!dcc_dbg) {
+ pr_err("can't create debugfs dir\n");
+ return;
+ }
+ }
+
+ dcc->dbg_dir = debugfs_create_dir(dev_name(dev), dcc_dbg);
+ if (!dcc->dbg_dir)
+ return;
+
+ debugfs_create_file("curr_list", 0400, dcc->dbg_dir, dcc, &curr_list_fops);
+ debugfs_create_file("enable", 0400, dcc->dbg_dir, dcc, &enable_fops);
+ debugfs_create_file("trigger", 0400, dcc->dbg_dir, dcc, &trigger_fops);
+ debugfs_create_file("config_read", 0400, dcc->dbg_dir, dcc, &config_fops);
+ debugfs_create_file("config_write", 0400, dcc->dbg_dir, dcc, &config_wr_fops);
+ debugfs_create_file("config_read_write", 0400, dcc->dbg_dir, dcc, &rd_mod_wr_fops);
+ debugfs_create_file("config_loop", 0400, dcc->dbg_dir, dcc, &loop_fops);
+ debugfs_create_file("ready", 0400, dcc->dbg_dir, dcc, &ready_fops);
+ debugfs_create_file("config_reset", 0400, dcc->dbg_dir, dcc, &config_reset_fops);
+}
+
+static ssize_t dcc_sram_read(struct file *file, char __user *data,
+ size_t len, loff_t *ppos)
+{
+ unsigned char *buf;
+ struct dcc_drvdata *drvdata = container_of(file->private_data,
+ struct dcc_drvdata,
+ sram_dev);
+
+ /* EOF check */
+ if (drvdata->ram_size <= *ppos)
+ return 0;
+
+ if ((*ppos + len) > drvdata->ram_size)
+ len = (drvdata->ram_size - *ppos);
+
+ buf = kzalloc(len, GFP_KERNEL);
+ if (!buf)
+ return -ENOMEM;
+
+ memcpy_fromio(buf, drvdata->ram_base + *ppos, len);
+
+ if (copy_to_user(data, buf, len)) {
+ kfree(buf);
+ return -EFAULT;
+ }
+
+ *ppos += len;
+
+ kfree(buf);
+
+ return len;
+}
+
+static const struct file_operations dcc_sram_fops = {
+ .owner = THIS_MODULE,
+ .read = dcc_sram_read,
+ .llseek = no_llseek,
+};
+
+static int dcc_sram_dev_init(struct dcc_drvdata *drvdata)
+{
+ int ret;
+
+ drvdata->sram_dev.minor = MISC_DYNAMIC_MINOR;
+ drvdata->sram_dev.name = DCC_SRAM_NODE;
+ drvdata->sram_dev.fops = &dcc_sram_fops;
+
+ ret = misc_register(&drvdata->sram_dev);
+ return ret;
+}
+
+static void dcc_sram_dev_exit(struct dcc_drvdata *drvdata)
+{
+ misc_deregister(&drvdata->sram_dev);
+}
+
+static int dcc_probe(struct platform_device *pdev)
+{
+ u32 val;
+ int ret = 0, i, enable_size, nr_config_size, cfg_head_size;
+ struct device *dev = &pdev->dev;
+ struct dcc_drvdata *dcc;
+ struct resource *res;
+
+ dcc = devm_kzalloc(dev, sizeof(*dcc), GFP_KERNEL);
+ if (!dcc)
+ return -ENOMEM;
+
+ dcc->dev = &pdev->dev;
+ platform_set_drvdata(pdev, dcc);
+
+ dcc->base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(dcc->base))
+ return PTR_ERR(dcc->base);
+
+ dcc->ram_base = devm_platform_get_and_ioremap_resource(pdev, 1, &res);
+ if (IS_ERR(dcc->ram_base))
+ return PTR_ERR(dcc->ram_base);
+
+ dcc->ram_size = resource_size(res);
+
+ dcc->ram_offset = (size_t) of_device_get_match_data(&pdev->dev);
+
+ val = dcc_readl(dcc, DCC_HW_INFO);
+
+ if (FIELD_GET(BIT(DCC_VER_INFO_BIT), val)) {
+ dcc->mem_map_ver = 3;
+ dcc->nr_link_list = dcc_readl(dcc, DCC_LL_NUM_INFO);
+ if (dcc->nr_link_list == 0)
+ return -EINVAL;
+ } else if ((val & DCC_VER_MASK2) == DCC_VER_MASK2) {
+ dcc->mem_map_ver = 2;
+ dcc->nr_link_list = dcc_readl(dcc, DCC_LL_NUM_INFO);
+ if (dcc->nr_link_list == 0)
+ return -EINVAL;
+ } else {
+ dcc->mem_map_ver = 1;
+ dcc->nr_link_list = DCC_MAX_LINK_LIST;
+ }
+
+ if ((val & DCC_LOOP_OFFSET_MASK) == DCC_LOOP_OFFSET_MASK)
+ dcc->loopoff = DCC_FIX_LOOP_OFFSET;
+ else
+ dcc->loopoff = get_bitmask_order((dcc->ram_size +
+ dcc->ram_offset) / 4 - 1);
+
+ mutex_init(&dcc->mutex);
+ /* Allocate space for all entries at once */
+ enable_size = dcc->nr_link_list * sizeof(bool);
+ nr_config_size = dcc->nr_link_list * sizeof(size_t);
+ cfg_head_size = dcc->nr_link_list * sizeof(struct list_head);
+
+ dcc->enable = devm_kzalloc(dev, enable_size + nr_config_size + cfg_head_size, GFP_KERNEL);
+ if (!dcc->enable)
+ return -ENOMEM;
+
+ dcc->nr_config = (size_t *)(dcc->enable + dcc->nr_link_list);
+ dcc->cfg_head = (struct list_head *)(dcc->nr_config + dcc->nr_link_list);
+
+ for (i = 0; i < dcc->nr_link_list; i++)
+ INIT_LIST_HEAD(&dcc->cfg_head[i]);
+
+ dcc->curr_list = DCC_INVALID_LINK_LIST;
+
+ ret = dcc_sram_dev_init(dcc);
+ if (ret) {
+ dev_err(dcc->dev, "DCC: sram node not registered.\n");
+ return ret;
+ }
+
+ dcc_create_debug_dir(dcc);
+
+ return 0;
+}
+
+static int dcc_remove(struct platform_device *pdev)
+{
+ struct dcc_drvdata *drvdata = platform_get_drvdata(pdev);
+
+ dcc_sram_dev_exit(drvdata);
+
+ dcc_delete_debug_dir(drvdata);
+
+ dcc_config_reset(drvdata);
+
+ return 0;
+}
+
+static const struct of_device_id dcc_match_table[] = {
+ { .compatible = "qcom,sm8150-dcc", .data = (void *)0x5000 },
+ { .compatible = "qcom,sc7280-dcc", .data = (void *)0x12000},
+ { .compatible = "qcom,sc7180-dcc", .data = (void *)0x6000 },
+ { .compatible = "qcom,sdm845-dcc", .data = (void *)0x6000 },
+ { }
+};
+MODULE_DEVICE_TABLE(of, dcc_match_table);
+
+static struct platform_driver dcc_driver = {
+ .probe = dcc_probe,
+ .remove = dcc_remove,
+ .driver = {
+ .name = "qcom-dcc",
+ .of_match_table = dcc_match_table,
+ },
+};
+
+module_platform_driver(dcc_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Qualcomm Technologies Inc. DCC driver");
+
--
2.7.4
On Thu 03 Mar 00:27 CST 2022, Souradeep Chowdhury wrote:
> The DCC is a DMA Engine designed to capture and store data
> during system crash or software triggers. The DCC operates
> based on user inputs via the sysfs interface. The user gives
> addresses as inputs and these addresses are stored in the
> dcc sram. In case of a system crash or a manual software
> trigger by the user through the debugfs interface,
> the dcc captures and stores the values at these addresses.
> This patch contains the driver which has all the methods
> pertaining to the debugfs interface, auxiliary functions to
> support all the four fundamental operations of dcc namely
> read, write, read/modify/write and loop. The probe method
> here instantiates all the resources necessary for dcc to
> operate mainly the dedicated dcc sram where it stores the
> values. The DCC driver can be used for debugging purposes
> without going for a reboot since it can perform software
> triggers as well based on user inputs.
>
> Also added the documentation for debugfs entries and explained
> the functionalities of each debugfs file that has been created
> for dcc.
>
> The following is the justification of using debugfs interface
> over the other alternatives like sysfs/ioctls
>
> i) As can be seen from the debugfs attribute descriptions,
> some of the debugfs attribute files here contains multiple
> arguments which needs to be accepted from the user. This goes
> against the design style of sysfs.
>
> ii) The user input patterns have been made simple and convenient
> in this case with the use of debugfs interface as user doesn't
> need to shuffle between different files to execute one instruction
> as was the case on using other alternatives.
>
> Signed-off-by: Souradeep Chowdhury <[email protected]>
> ---
> Documentation/ABI/testing/debugfs-driver-dcc | 124 +++
> drivers/soc/qcom/Kconfig | 8 +
> drivers/soc/qcom/Makefile | 1 +
> drivers/soc/qcom/dcc.c | 1465 ++++++++++++++++++++++++++
> 4 files changed, 1598 insertions(+)
> create mode 100644 Documentation/ABI/testing/debugfs-driver-dcc
> create mode 100644 drivers/soc/qcom/dcc.c
>
> diff --git a/Documentation/ABI/testing/debugfs-driver-dcc b/Documentation/ABI/testing/debugfs-driver-dcc
> new file mode 100644
> index 0000000..70029ab
> --- /dev/null
> +++ b/Documentation/ABI/testing/debugfs-driver-dcc
> @@ -0,0 +1,124 @@
> +What: /sys/kernel/debug/dcc/.../trigger
> +Date: March 2022
> +Contact: Souradeep Chowdhury <[email protected]>
> +Description:
> + This is the debugfs interface for manual software
> + triggers. The user can simply enter a 1 against
> + the debugfs file and enable a manual trigger.
> + Example:
> + echo 1 > /sys/kernel/debug/dcc/.../trigger
> +
> +What: /sys/kernel/debug/dcc/.../enable
> +Date: March 2022
> +Contact: Souradeep Chowdhury <[email protected]>
> +Description:
> + This debugfs interface is used for enabling the
> + the dcc hardware. On enabling the dcc, all the
> + addresses entered by the user is written into
> + dcc sram which is read by the dcc hardware on
> + manual or crash induced triggers.
> + Example:
> + echo 0 > /sys/bus/platform/devices/.../enable
> + (disable dcc)
> + echo 1 > /sys/bus/platform/devices/.../enable
> + (enable dcc)
> +
> +What: /sys/kernel/debug/dcc/.../config_read
As mentioned last time, I don't like this interface of having 6 files
that the user can write to in order to append items in the currently
selected linked list.
Why can't this be a single "config" which takes a multiline string of
operations? (Bonus point for supporting appending to the list).
This would also serve as a natural place to dump the linked list back to
the user for inspection.
> +Date: March 2022
> +Contact: Souradeep Chowdhury <[email protected]>
> +Description:
> + This stores the addresses of the registers which
> + needs to be read in case of a hardware crash or
> + manual software triggers. The address entered here
> + are considered under read type instruction.
> + Example:
> + echo <1> <2> <3> >/sys/kernel/debug/dcc/../config_read
> + 1->Address to be considered for reading the value.
> + 2->The word count of the addresses, read n words
> + starting from address <1>.
> + 3->Can be a 1 or 0 which indicates if it is apb or ahb
> + bus respectively.
> +
> +What: /sys/kernel/debug/dcc/.../config_write
> +Date: March 2022
> +Contact: Souradeep Chowdhury <[email protected]>
> +Description:
> + This file allows user to write a value to the register
> + address given as argument. The reason for this feature
> + of dcc is that for accessing certain registers it is
> + necessary to set some bits of some other register.
> + Example:
> + echo <1> <2> <3> > /sys/bus/platform/devices/.../config_write
> + 1->Address to be considered for writing the value.
> + 2->The value that needs to be written at the location.
> + 3->Can be a 1 or 0 which indicates if it is apb or ahb
> + bus respectively.
> +
> +What: /sys/kernel/debug/dcc/.../config_reset
> +Date: March 2022
> +Contact: Souradeep Chowdhury <[email protected]>
> +Description:
> + This file is used to reset the configuration of
> + a dcc driver to the default configuration. This
> + means that all the previous addresses stored in
> + the driver gets removed and user needs to enter
> + the address values from the start.
> + Example:
> + echo 1 > /sys/bus/platform/devices/.../config_reset
> +
> +What: /sys/kernel/debug/dcc/.../config_loop
> +Date: March 2022
> +Contact: Souradeep Chowdhury <[email protected]>
> +Description:
> + This file is used to enter the loop type addresses for
> + dcc. DCC hardware provides feature to loop among multiple
> + addresses. For debugging purposes register values need to
> + be captured repeatedly in a loop. On giving the loop count
> + as n, the value at address will be captured n times in a
> + loop. At most 8 loop addresses can be configured at once.
> + Example:
> + echo <1> <2> <3> > /sys/kernel/debug/dcc/../config_loop
> + 1->The loop count, the number of times the value of the
> + addresses will be captured.
> + 2->The address count, total number of addresses to be
> + entered in this instruction.
> + 3->The series of addresses to be entered separated by a
> + space like <addr1> <addr2>... and so on.
> +
> +What: /sys/kernel/debug/dcc/.../config_read_write
> +Date: March 2022
> +Contact: Souradeep Chowdhury <[email protected]>
> +Description:
> + This file is used to read the value of the register
> + and then write the value given as an argument to the
> + register address. The address argument should be given
> + of the form <addr> <mask> <value>.For debugging purposes
> + sometimes we need to first read from a register and then
> + set some values to the register.
> + Example:
> + echo <1> <2> <3> > /sys/kernel/debug/dcc/.../config_read_write
> + 1->The address which needs to be considered for read then write.
> + 2->The value that needs to be written on the address.
> + 3->The mask of the value to be written.
> +
> +What: /sys/kernel/debug/dcc/.../ready
> +Date: March 2022
> +Contact Souradeep Chowdhury <[email protected]>
> +Description:
> + This file is used to check the status of the dcc
> + hardware if it's ready to take the inputs. A 0
> + here indicates dcc is in a ready condition.
> + Example:
> + cat /sys/kernel/debug/dcc/.../ready
> +
> +What: /sys/kernel/debug/dcc/.../curr_list
I still don't like the idea of having a single set of files to interface
with all N lists. I think you should discover how many lists you have
and create N directories of files, each on operating on a given list.
> +Date: March 2022
> +Contact: Souradeep Chowdhury <[email protected]>
> +Description:
> + This attribute is used to enter the linklist to be
> + used while appending addresses. The range of values
> + for this is advertised either by a register or is
> + predefined. Max value for this can be till 8.
> + Example:
> + echo 0 > /sys/kernel/debug/dcc/...curr_list
> +
Regards,
Bjorn
On Thu 05 May 05:53 PDT 2022, Souradeep Chowdhury wrote:
>
> On 5/3/2022 11:33 PM, Bjorn Andersson wrote:
> > On Thu 03 Mar 00:27 CST 2022, Souradeep Chowdhury wrote:
> >
> > > The DCC is a DMA Engine designed to capture and store data
> > > during system crash or software triggers. The DCC operates
> > > based on user inputs via the sysfs interface. The user gives
> > > addresses as inputs and these addresses are stored in the
> > > dcc sram. In case of a system crash or a manual software
> > > trigger by the user through the debugfs interface,
> > > the dcc captures and stores the values at these addresses.
> > > This patch contains the driver which has all the methods
> > > pertaining to the debugfs interface, auxiliary functions to
> > > support all the four fundamental operations of dcc namely
> > > read, write, read/modify/write and loop. The probe method
> > > here instantiates all the resources necessary for dcc to
> > > operate mainly the dedicated dcc sram where it stores the
> > > values. The DCC driver can be used for debugging purposes
> > > without going for a reboot since it can perform software
> > > triggers as well based on user inputs.
> > >
> > > Also added the documentation for debugfs entries and explained
> > > the functionalities of each debugfs file that has been created
> > > for dcc.
> > >
> > > The following is the justification of using debugfs interface
> > > over the other alternatives like sysfs/ioctls
> > >
> > > i) As can be seen from the debugfs attribute descriptions,
> > > some of the debugfs attribute files here contains multiple
> > > arguments which needs to be accepted from the user. This goes
> > > against the design style of sysfs.
> > >
> > > ii) The user input patterns have been made simple and convenient
> > > in this case with the use of debugfs interface as user doesn't
> > > need to shuffle between different files to execute one instruction
> > > as was the case on using other alternatives.
> > >
> > > Signed-off-by: Souradeep Chowdhury <[email protected]>
> > > ---
> > > Documentation/ABI/testing/debugfs-driver-dcc | 124 +++
> > > drivers/soc/qcom/Kconfig | 8 +
> > > drivers/soc/qcom/Makefile | 1 +
> > > drivers/soc/qcom/dcc.c | 1465 ++++++++++++++++++++++++++
> > > 4 files changed, 1598 insertions(+)
> > > create mode 100644 Documentation/ABI/testing/debugfs-driver-dcc
> > > create mode 100644 drivers/soc/qcom/dcc.c
> > >
> > > diff --git a/Documentation/ABI/testing/debugfs-driver-dcc b/Documentation/ABI/testing/debugfs-driver-dcc
> > > new file mode 100644
> > > index 0000000..70029ab
> > > --- /dev/null
> > > +++ b/Documentation/ABI/testing/debugfs-driver-dcc
> > > @@ -0,0 +1,124 @@
> > > +What: /sys/kernel/debug/dcc/.../trigger
> > > +Date: March 2022
> > > +Contact: Souradeep Chowdhury <[email protected]>
> > > +Description:
> > > + This is the debugfs interface for manual software
> > > + triggers. The user can simply enter a 1 against
> > > + the debugfs file and enable a manual trigger.
> > > + Example:
> > > + echo 1 > /sys/kernel/debug/dcc/.../trigger
> > > +
> > > +What: /sys/kernel/debug/dcc/.../enable
> > > +Date: March 2022
> > > +Contact: Souradeep Chowdhury <[email protected]>
> > > +Description:
> > > + This debugfs interface is used for enabling the
> > > + the dcc hardware. On enabling the dcc, all the
> > > + addresses entered by the user is written into
> > > + dcc sram which is read by the dcc hardware on
> > > + manual or crash induced triggers.
> > > + Example:
> > > + echo 0 > /sys/bus/platform/devices/.../enable
> > > + (disable dcc)
> > > + echo 1 > /sys/bus/platform/devices/.../enable
> > > + (enable dcc)
> > > +
> > > +What: /sys/kernel/debug/dcc/.../config_read
> > As mentioned last time, I don't like this interface of having 6 files
> > that the user can write to in order to append items in the currently
> > selected linked list.
> >
> > Why can't this be a single "config" which takes a multiline string of
> > operations? (Bonus point for supporting appending to the list).
> >
> >
> > This would also serve as a natural place to dump the linked list back to
> > the user for inspection.
>
> Following is the justification of having multiple files in debugfs
>
> 1-> Since there are fundamentally 4 instructions for DCC, Read,Write,Read
> and then Write and Loop,having separate debugfs files for the same makes it
>
> convenient for the user to use this tool and also to document.This
> also is consistent with the design principles of debugfs as it supports
> logical segregation of Debugfs files based on the user instructions.
>
So say the user of DCC wants to read a register 10 times, they know that
the DCC operates on lists of operations, so they want to tell the
computer "read X, loop 10 times".
But the API is "write to loop file", "write to read file" and "write to
loop file".
You're achieving the same thing, but the user and the driver thinks in
terms of lists of operations and inbetween is a API which provides
"logical segregation" of the different parts of that list.
> 2-> We are maintaining a common linkedlist inside the driver and it can be
> viewed by the user through the "config_read" debugfs file. Will be adding
> this to the documentation as well.
>
So I use a mix of config_* files to build the lists, and then
config_read is used to look at the list?
So some config_* files will when written append to the list, some
config_* files will perform some action (e.g. reset) and reading some
config_* files will return something useful.
> Let me know your thoughts regarding the above.
>
I am not convinced that having multiple files provides a nice user
interface. But I certain that the use of the word "config" in various
different ways is wrong.
There are files in the interface which purpose is to append items to the
linked list, name them append_*. Reading the appended items on the list
should not be overloaded on one of the "append" files.
So perhaps:
append_read
append_write
append_rmw
append_loop
config (to dump the current config)
enable
ready
reset
trigger
But then looking at the append_* functions again and the examples below.
You could easily have a single append which takes read, write, rmw and
loop as a first keyword - and build a crude parser based on sscanf to
decode the strings.
Then all append_* becomes "append", which is a single file for adding to
the list and "config" is a single point to read the current list.
Perhaps you could name this file just "config", reading will dump the
list, writing will append to the list.
Here you would have a cleaner interface.
But as you write your own fops you could differentiate between write
and append, so you could make this slightly cleaner by manifesting the
"append" part by allowing the user to do:
echo read 1, 2, 3 > config
echo read 4, 5, 6 >> config
Which clearly shows that the first writes to the config and second
appends to the current config. With this interface reset would become:
echo > config
You can still require that only single operation is written to or
appended to the list per write - to allow you to continue to rely on the
crude sscanf based parser.
With this your interface is reduced to:
config
enable
ready
trigger
> > > +Date: March 2022
> > > +Contact: Souradeep Chowdhury <[email protected]>
> > > +Description:
> > > + This stores the addresses of the registers which
> > > + needs to be read in case of a hardware crash or
> > > + manual software triggers. The address entered here
> > > + are considered under read type instruction.
> > > + Example:
> > > + echo <1> <2> <3> >/sys/kernel/debug/dcc/../config_read
> > > + 1->Address to be considered for reading the value.
> > > + 2->The word count of the addresses, read n words
> > > + starting from address <1>.
> > > + 3->Can be a 1 or 0 which indicates if it is apb or ahb
> > > + bus respectively.
> > > +
> > > +What: /sys/kernel/debug/dcc/.../config_write
> > > +Date: March 2022
> > > +Contact: Souradeep Chowdhury <[email protected]>
> > > +Description:
> > > + This file allows user to write a value to the register
> > > + address given as argument. The reason for this feature
> > > + of dcc is that for accessing certain registers it is
> > > + necessary to set some bits of some other register.
> > > + Example:
> > > + echo <1> <2> <3> > /sys/bus/platform/devices/.../config_write
> > > + 1->Address to be considered for writing the value.
> > > + 2->The value that needs to be written at the location.
> > > + 3->Can be a 1 or 0 which indicates if it is apb or ahb
> > > + bus respectively.
> > > +
> > > +What: /sys/kernel/debug/dcc/.../config_reset
> > > +Date: March 2022
> > > +Contact: Souradeep Chowdhury <[email protected]>
> > > +Description:
> > > + This file is used to reset the configuration of
> > > + a dcc driver to the default configuration. This
> > > + means that all the previous addresses stored in
> > > + the driver gets removed and user needs to enter
> > > + the address values from the start.
> > > + Example:
> > > + echo 1 > /sys/bus/platform/devices/.../config_reset
> > > +
> > > +What: /sys/kernel/debug/dcc/.../config_loop
> > > +Date: March 2022
> > > +Contact: Souradeep Chowdhury <[email protected]>
> > > +Description:
> > > + This file is used to enter the loop type addresses for
> > > + dcc. DCC hardware provides feature to loop among multiple
> > > + addresses. For debugging purposes register values need to
> > > + be captured repeatedly in a loop. On giving the loop count
> > > + as n, the value at address will be captured n times in a
> > > + loop. At most 8 loop addresses can be configured at once.
> > > + Example:
> > > + echo <1> <2> <3> > /sys/kernel/debug/dcc/../config_loop
> > > + 1->The loop count, the number of times the value of the
> > > + addresses will be captured.
> > > + 2->The address count, total number of addresses to be
> > > + entered in this instruction.
> > > + 3->The series of addresses to be entered separated by a
> > > + space like <addr1> <addr2>... and so on.
> > > +
> > > +What: /sys/kernel/debug/dcc/.../config_read_write
> > > +Date: March 2022
> > > +Contact: Souradeep Chowdhury <[email protected]>
> > > +Description:
> > > + This file is used to read the value of the register
> > > + and then write the value given as an argument to the
> > > + register address. The address argument should be given
> > > + of the form <addr> <mask> <value>.For debugging purposes
> > > + sometimes we need to first read from a register and then
> > > + set some values to the register.
> > > + Example:
> > > + echo <1> <2> <3> > /sys/kernel/debug/dcc/.../config_read_write
> > > + 1->The address which needs to be considered for read then write.
> > > + 2->The value that needs to be written on the address.
> > > + 3->The mask of the value to be written.
> > > +
> > > +What: /sys/kernel/debug/dcc/.../ready
> > > +Date: March 2022
> > > +Contact Souradeep Chowdhury <[email protected]>
> > > +Description:
> > > + This file is used to check the status of the dcc
> > > + hardware if it's ready to take the inputs. A 0
> > > + here indicates dcc is in a ready condition.
> > > + Example:
> > > + cat /sys/kernel/debug/dcc/.../ready
> > > +
> > > +What: /sys/kernel/debug/dcc/.../curr_list
> > I still don't like the idea of having a single set of files to interface
> > with all N lists. I think you should discover how many lists you have
> > and create N directories of files, each on operating on a given list.
>
> As explained before there cannot be different files based on lists as
> the number of lists to be used varies across platforms where DCC is
> used.
Isn't this dcc->nr_link_list?
> Also we are giving the user the flexibility to configure
> multiple lists at one go whereas the dumps are collected in the form
> of separate lists that are configured by the user.
>
I'm not sure I follow what you're trying to say here.
If we determine that nr_link_list is 2, you create a directory named 0
and one named 1, fill them with the interface files to operate on list 0
and list 1 respectively. Then you still allow the user to configure and
enable the 2 available lists?
The difference is that it's clear how many lists you have and it's clear
when you poke at 0/config_read that you're referring to the first list
and poking 0/enable will mean the same list - there's no curr_list to
mux between them in the interface.
Regards,
Bjorn
> >
> > > +Date: March 2022
> > > +Contact: Souradeep Chowdhury <[email protected]>
> > > +Description:
> > > + This attribute is used to enter the linklist to be
> > > + used while appending addresses. The range of values
> > > + for this is advertised either by a register or is
> > > + predefined. Max value for this can be till 8.
> > > + Example:
> > > + echo 0 > /sys/kernel/debug/dcc/...curr_list
> > > +
> > Regards,
> > Bjorn
On 5/3/2022 11:33 PM, Bjorn Andersson wrote:
> On Thu 03 Mar 00:27 CST 2022, Souradeep Chowdhury wrote:
>
>> The DCC is a DMA Engine designed to capture and store data
>> during system crash or software triggers. The DCC operates
>> based on user inputs via the sysfs interface. The user gives
>> addresses as inputs and these addresses are stored in the
>> dcc sram. In case of a system crash or a manual software
>> trigger by the user through the debugfs interface,
>> the dcc captures and stores the values at these addresses.
>> This patch contains the driver which has all the methods
>> pertaining to the debugfs interface, auxiliary functions to
>> support all the four fundamental operations of dcc namely
>> read, write, read/modify/write and loop. The probe method
>> here instantiates all the resources necessary for dcc to
>> operate mainly the dedicated dcc sram where it stores the
>> values. The DCC driver can be used for debugging purposes
>> without going for a reboot since it can perform software
>> triggers as well based on user inputs.
>>
>> Also added the documentation for debugfs entries and explained
>> the functionalities of each debugfs file that has been created
>> for dcc.
>>
>> The following is the justification of using debugfs interface
>> over the other alternatives like sysfs/ioctls
>>
>> i) As can be seen from the debugfs attribute descriptions,
>> some of the debugfs attribute files here contains multiple
>> arguments which needs to be accepted from the user. This goes
>> against the design style of sysfs.
>>
>> ii) The user input patterns have been made simple and convenient
>> in this case with the use of debugfs interface as user doesn't
>> need to shuffle between different files to execute one instruction
>> as was the case on using other alternatives.
>>
>> Signed-off-by: Souradeep Chowdhury <[email protected]>
>> ---
>> Documentation/ABI/testing/debugfs-driver-dcc | 124 +++
>> drivers/soc/qcom/Kconfig | 8 +
>> drivers/soc/qcom/Makefile | 1 +
>> drivers/soc/qcom/dcc.c | 1465 ++++++++++++++++++++++++++
>> 4 files changed, 1598 insertions(+)
>> create mode 100644 Documentation/ABI/testing/debugfs-driver-dcc
>> create mode 100644 drivers/soc/qcom/dcc.c
>>
>> diff --git a/Documentation/ABI/testing/debugfs-driver-dcc b/Documentation/ABI/testing/debugfs-driver-dcc
>> new file mode 100644
>> index 0000000..70029ab
>> --- /dev/null
>> +++ b/Documentation/ABI/testing/debugfs-driver-dcc
>> @@ -0,0 +1,124 @@
>> +What: /sys/kernel/debug/dcc/.../trigger
>> +Date: March 2022
>> +Contact: Souradeep Chowdhury <[email protected]>
>> +Description:
>> + This is the debugfs interface for manual software
>> + triggers. The user can simply enter a 1 against
>> + the debugfs file and enable a manual trigger.
>> + Example:
>> + echo 1 > /sys/kernel/debug/dcc/.../trigger
>> +
>> +What: /sys/kernel/debug/dcc/.../enable
>> +Date: March 2022
>> +Contact: Souradeep Chowdhury <[email protected]>
>> +Description:
>> + This debugfs interface is used for enabling the
>> + the dcc hardware. On enabling the dcc, all the
>> + addresses entered by the user is written into
>> + dcc sram which is read by the dcc hardware on
>> + manual or crash induced triggers.
>> + Example:
>> + echo 0 > /sys/bus/platform/devices/.../enable
>> + (disable dcc)
>> + echo 1 > /sys/bus/platform/devices/.../enable
>> + (enable dcc)
>> +
>> +What: /sys/kernel/debug/dcc/.../config_read
> As mentioned last time, I don't like this interface of having 6 files
> that the user can write to in order to append items in the currently
> selected linked list.
>
> Why can't this be a single "config" which takes a multiline string of
> operations? (Bonus point for supporting appending to the list).
>
>
> This would also serve as a natural place to dump the linked list back to
> the user for inspection.
Following is the justification of having multiple files in debugfs
1-> Since there are fundamentally 4 instructions for DCC,
Read,Write,Read and then Write and Loop,having separate debugfs files
for the same makes it
convenient for the user to use this tool and also to
document.This also is consistent with the design principles of debugfs
as it supports logical segregation
of Debugfs files based on the user instructions.
2-> We are maintaining a common linkedlist inside the driver and it can
be viewed by the user through the "config_read" debugfs file. Will be
adding this to the
documentation as well.
Let me know your thoughts regarding the above.
>> +Date: March 2022
>> +Contact: Souradeep Chowdhury <[email protected]>
>> +Description:
>> + This stores the addresses of the registers which
>> + needs to be read in case of a hardware crash or
>> + manual software triggers. The address entered here
>> + are considered under read type instruction.
>> + Example:
>> + echo <1> <2> <3> >/sys/kernel/debug/dcc/../config_read
>> + 1->Address to be considered for reading the value.
>> + 2->The word count of the addresses, read n words
>> + starting from address <1>.
>> + 3->Can be a 1 or 0 which indicates if it is apb or ahb
>> + bus respectively.
>> +
>> +What: /sys/kernel/debug/dcc/.../config_write
>> +Date: March 2022
>> +Contact: Souradeep Chowdhury <[email protected]>
>> +Description:
>> + This file allows user to write a value to the register
>> + address given as argument. The reason for this feature
>> + of dcc is that for accessing certain registers it is
>> + necessary to set some bits of some other register.
>> + Example:
>> + echo <1> <2> <3> > /sys/bus/platform/devices/.../config_write
>> + 1->Address to be considered for writing the value.
>> + 2->The value that needs to be written at the location.
>> + 3->Can be a 1 or 0 which indicates if it is apb or ahb
>> + bus respectively.
>> +
>> +What: /sys/kernel/debug/dcc/.../config_reset
>> +Date: March 2022
>> +Contact: Souradeep Chowdhury <[email protected]>
>> +Description:
>> + This file is used to reset the configuration of
>> + a dcc driver to the default configuration. This
>> + means that all the previous addresses stored in
>> + the driver gets removed and user needs to enter
>> + the address values from the start.
>> + Example:
>> + echo 1 > /sys/bus/platform/devices/.../config_reset
>> +
>> +What: /sys/kernel/debug/dcc/.../config_loop
>> +Date: March 2022
>> +Contact: Souradeep Chowdhury <[email protected]>
>> +Description:
>> + This file is used to enter the loop type addresses for
>> + dcc. DCC hardware provides feature to loop among multiple
>> + addresses. For debugging purposes register values need to
>> + be captured repeatedly in a loop. On giving the loop count
>> + as n, the value at address will be captured n times in a
>> + loop. At most 8 loop addresses can be configured at once.
>> + Example:
>> + echo <1> <2> <3> > /sys/kernel/debug/dcc/../config_loop
>> + 1->The loop count, the number of times the value of the
>> + addresses will be captured.
>> + 2->The address count, total number of addresses to be
>> + entered in this instruction.
>> + 3->The series of addresses to be entered separated by a
>> + space like <addr1> <addr2>... and so on.
>> +
>> +What: /sys/kernel/debug/dcc/.../config_read_write
>> +Date: March 2022
>> +Contact: Souradeep Chowdhury <[email protected]>
>> +Description:
>> + This file is used to read the value of the register
>> + and then write the value given as an argument to the
>> + register address. The address argument should be given
>> + of the form <addr> <mask> <value>.For debugging purposes
>> + sometimes we need to first read from a register and then
>> + set some values to the register.
>> + Example:
>> + echo <1> <2> <3> > /sys/kernel/debug/dcc/.../config_read_write
>> + 1->The address which needs to be considered for read then write.
>> + 2->The value that needs to be written on the address.
>> + 3->The mask of the value to be written.
>> +
>> +What: /sys/kernel/debug/dcc/.../ready
>> +Date: March 2022
>> +Contact Souradeep Chowdhury <[email protected]>
>> +Description:
>> + This file is used to check the status of the dcc
>> + hardware if it's ready to take the inputs. A 0
>> + here indicates dcc is in a ready condition.
>> + Example:
>> + cat /sys/kernel/debug/dcc/.../ready
>> +
>> +What: /sys/kernel/debug/dcc/.../curr_list
> I still don't like the idea of having a single set of files to interface
> with all N lists. I think you should discover how many lists you have
> and create N directories of files, each on operating on a given list.
As explained before there cannot be different files based on lists as
the number of lists to be used
varies across platforms where DCC is used. Also we are giving the user
the flexibility to configure
multiple lists at one go whereas the dumps are collected in the form of
separate lists that are
configured by the user.
>
>> +Date: March 2022
>> +Contact: Souradeep Chowdhury <[email protected]>
>> +Description:
>> + This attribute is used to enter the linklist to be
>> + used while appending addresses. The range of values
>> + for this is advertised either by a register or is
>> + predefined. Max value for this can be till 8.
>> + Example:
>> + echo 0 > /sys/kernel/debug/dcc/...curr_list
>> +
> Regards,
> Bjorn
On 5/6/2022 8:23 AM, Bjorn Andersson wrote:
> On Thu 05 May 05:53 PDT 2022, Souradeep Chowdhury wrote:
>
>> On 5/3/2022 11:33 PM, Bjorn Andersson wrote:
>>> On Thu 03 Mar 00:27 CST 2022, Souradeep Chowdhury wrote:
>>>
>>>> The DCC is a DMA Engine designed to capture and store data
>>>> during system crash or software triggers. The DCC operates
>>>> based on user inputs via the sysfs interface. The user gives
>>>> addresses as inputs and these addresses are stored in the
>>>> dcc sram. In case of a system crash or a manual software
>>>> trigger by the user through the debugfs interface,
>>>> the dcc captures and stores the values at these addresses.
>>>> This patch contains the driver which has all the methods
>>>> pertaining to the debugfs interface, auxiliary functions to
>>>> support all the four fundamental operations of dcc namely
>>>> read, write, read/modify/write and loop. The probe method
>>>> here instantiates all the resources necessary for dcc to
>>>> operate mainly the dedicated dcc sram where it stores the
>>>> values. The DCC driver can be used for debugging purposes
>>>> without going for a reboot since it can perform software
>>>> triggers as well based on user inputs.
>>>>
>>>> Also added the documentation for debugfs entries and explained
>>>> the functionalities of each debugfs file that has been created
>>>> for dcc.
>>>>
>>>> The following is the justification of using debugfs interface
>>>> over the other alternatives like sysfs/ioctls
>>>>
>>>> i) As can be seen from the debugfs attribute descriptions,
>>>> some of the debugfs attribute files here contains multiple
>>>> arguments which needs to be accepted from the user. This goes
>>>> against the design style of sysfs.
>>>>
>>>> ii) The user input patterns have been made simple and convenient
>>>> in this case with the use of debugfs interface as user doesn't
>>>> need to shuffle between different files to execute one instruction
>>>> as was the case on using other alternatives.
>>>>
>>>> Signed-off-by: Souradeep Chowdhury <[email protected]>
>>>> ---
>>>> Documentation/ABI/testing/debugfs-driver-dcc | 124 +++
>>>> drivers/soc/qcom/Kconfig | 8 +
>>>> drivers/soc/qcom/Makefile | 1 +
>>>> drivers/soc/qcom/dcc.c | 1465 ++++++++++++++++++++++++++
>>>> 4 files changed, 1598 insertions(+)
>>>> create mode 100644 Documentation/ABI/testing/debugfs-driver-dcc
>>>> create mode 100644 drivers/soc/qcom/dcc.c
>>>>
>>>> diff --git a/Documentation/ABI/testing/debugfs-driver-dcc b/Documentation/ABI/testing/debugfs-driver-dcc
>>>> new file mode 100644
>>>> index 0000000..70029ab
>>>> --- /dev/null
>>>> +++ b/Documentation/ABI/testing/debugfs-driver-dcc
>>>> @@ -0,0 +1,124 @@
>>>> +What: /sys/kernel/debug/dcc/.../trigger
>>>> +Date: March 2022
>>>> +Contact: Souradeep Chowdhury <[email protected]>
>>>> +Description:
>>>> + This is the debugfs interface for manual software
>>>> + triggers. The user can simply enter a 1 against
>>>> + the debugfs file and enable a manual trigger.
>>>> + Example:
>>>> + echo 1 > /sys/kernel/debug/dcc/.../trigger
>>>> +
>>>> +What: /sys/kernel/debug/dcc/.../enable
>>>> +Date: March 2022
>>>> +Contact: Souradeep Chowdhury <[email protected]>
>>>> +Description:
>>>> + This debugfs interface is used for enabling the
>>>> + the dcc hardware. On enabling the dcc, all the
>>>> + addresses entered by the user is written into
>>>> + dcc sram which is read by the dcc hardware on
>>>> + manual or crash induced triggers.
>>>> + Example:
>>>> + echo 0 > /sys/bus/platform/devices/.../enable
>>>> + (disable dcc)
>>>> + echo 1 > /sys/bus/platform/devices/.../enable
>>>> + (enable dcc)
>>>> +
>>>> +What: /sys/kernel/debug/dcc/.../config_read
>>> As mentioned last time, I don't like this interface of having 6 files
>>> that the user can write to in order to append items in the currently
>>> selected linked list.
>>>
>>> Why can't this be a single "config" which takes a multiline string of
>>> operations? (Bonus point for supporting appending to the list).
>>>
>>>
>>> This would also serve as a natural place to dump the linked list back to
>>> the user for inspection.
>> Following is the justification of having multiple files in debugfs
>>
>> 1-> Since there are fundamentally 4 instructions for DCC, Read,Write,Read
>> and then Write and Loop,having separate debugfs files for the same makes it
>>
>> convenient for the user to use this tool and also to document.This
>> also is consistent with the design principles of debugfs as it supports
>> logical segregation of Debugfs files based on the user instructions.
>>
> So say the user of DCC wants to read a register 10 times, they know that
> the DCC operates on lists of operations, so they want to tell the
> computer "read X, loop 10 times".
>
> But the API is "write to loop file", "write to read file" and "write to
> loop file".
>
> You're achieving the same thing, but the user and the driver thinks in
> terms of lists of operations and inbetween is a API which provides
> "logical segregation" of the different parts of that list.
>
>> 2-> We are maintaining a common linkedlist inside the driver and it can be
>> viewed by the user through the "config_read" debugfs file. Will be adding
>> this to the documentation as well.
>>
> So I use a mix of config_* files to build the lists, and then
> config_read is used to look at the list?
>
> So some config_* files will when written append to the list, some
> config_* files will perform some action (e.g. reset) and reading some
> config_* files will return something useful.
>
>> Let me know your thoughts regarding the above.
>>
> I am not convinced that having multiple files provides a nice user
> interface. But I certain that the use of the word "config" in various
> different ways is wrong.
>
> There are files in the interface which purpose is to append items to the
> linked list, name them append_*. Reading the appended items on the list
> should not be overloaded on one of the "append" files.
>
>
> So perhaps:
>
> append_read
> append_write
> append_rmw
> append_loop
> config (to dump the current config)
> enable
> ready
> reset
> trigger
>
>
> But then looking at the append_* functions again and the examples below.
> You could easily have a single append which takes read, write, rmw and
> loop as a first keyword - and build a crude parser based on sscanf to
> decode the strings.
>
> Then all append_* becomes "append", which is a single file for adding to
> the list and "config" is a single point to read the current list.
> Perhaps you could name this file just "config", reading will dump the
> list, writing will append to the list.
>
> Here you would have a cleaner interface.
>
>
> But as you write your own fops you could differentiate between write
> and append, so you could make this slightly cleaner by manifesting the
> "append" part by allowing the user to do:
>
> echo read 1, 2, 3 > config
> echo read 4, 5, 6 >> config
>
> Which clearly shows that the first writes to the config and second
> appends to the current config. With this interface reset would become:
>
> echo > config
>
> You can still require that only single operation is written to or
> appended to the list per write - to allow you to continue to rely on the
> crude sscanf based parser.
>
> With this your interface is reduced to:
>
> config
> enable
> ready
> trigger
Ack. Will create a single config for this interface.
>
>>>> +Date: March 2022
>>>> +Contact: Souradeep Chowdhury <[email protected]>
>>>> +Description:
>>>> + This stores the addresses of the registers which
>>>> + needs to be read in case of a hardware crash or
>>>> + manual software triggers. The address entered here
>>>> + are considered under read type instruction.
>>>> + Example:
>>>> + echo <1> <2> <3> >/sys/kernel/debug/dcc/../config_read
>>>> + 1->Address to be considered for reading the value.
>>>> + 2->The word count of the addresses, read n words
>>>> + starting from address <1>.
>>>> + 3->Can be a 1 or 0 which indicates if it is apb or ahb
>>>> + bus respectively.
>>>> +
>>>> +What: /sys/kernel/debug/dcc/.../config_write
>>>> +Date: March 2022
>>>> +Contact: Souradeep Chowdhury <[email protected]>
>>>> +Description:
>>>> + This file allows user to write a value to the register
>>>> + address given as argument. The reason for this feature
>>>> + of dcc is that for accessing certain registers it is
>>>> + necessary to set some bits of some other register.
>>>> + Example:
>>>> + echo <1> <2> <3> > /sys/bus/platform/devices/.../config_write
>>>> + 1->Address to be considered for writing the value.
>>>> + 2->The value that needs to be written at the location.
>>>> + 3->Can be a 1 or 0 which indicates if it is apb or ahb
>>>> + bus respectively.
>>>> +
>>>> +What: /sys/kernel/debug/dcc/.../config_reset
>>>> +Date: March 2022
>>>> +Contact: Souradeep Chowdhury <[email protected]>
>>>> +Description:
>>>> + This file is used to reset the configuration of
>>>> + a dcc driver to the default configuration. This
>>>> + means that all the previous addresses stored in
>>>> + the driver gets removed and user needs to enter
>>>> + the address values from the start.
>>>> + Example:
>>>> + echo 1 > /sys/bus/platform/devices/.../config_reset
>>>> +
>>>> +What: /sys/kernel/debug/dcc/.../config_loop
>>>> +Date: March 2022
>>>> +Contact: Souradeep Chowdhury <[email protected]>
>>>> +Description:
>>>> + This file is used to enter the loop type addresses for
>>>> + dcc. DCC hardware provides feature to loop among multiple
>>>> + addresses. For debugging purposes register values need to
>>>> + be captured repeatedly in a loop. On giving the loop count
>>>> + as n, the value at address will be captured n times in a
>>>> + loop. At most 8 loop addresses can be configured at once.
>>>> + Example:
>>>> + echo <1> <2> <3> > /sys/kernel/debug/dcc/../config_loop
>>>> + 1->The loop count, the number of times the value of the
>>>> + addresses will be captured.
>>>> + 2->The address count, total number of addresses to be
>>>> + entered in this instruction.
>>>> + 3->The series of addresses to be entered separated by a
>>>> + space like <addr1> <addr2>... and so on.
>>>> +
>>>> +What: /sys/kernel/debug/dcc/.../config_read_write
>>>> +Date: March 2022
>>>> +Contact: Souradeep Chowdhury <[email protected]>
>>>> +Description:
>>>> + This file is used to read the value of the register
>>>> + and then write the value given as an argument to the
>>>> + register address. The address argument should be given
>>>> + of the form <addr> <mask> <value>.For debugging purposes
>>>> + sometimes we need to first read from a register and then
>>>> + set some values to the register.
>>>> + Example:
>>>> + echo <1> <2> <3> > /sys/kernel/debug/dcc/.../config_read_write
>>>> + 1->The address which needs to be considered for read then write.
>>>> + 2->The value that needs to be written on the address.
>>>> + 3->The mask of the value to be written.
>>>> +
>>>> +What: /sys/kernel/debug/dcc/.../ready
>>>> +Date: March 2022
>>>> +Contact Souradeep Chowdhury <[email protected]>
>>>> +Description:
>>>> + This file is used to check the status of the dcc
>>>> + hardware if it's ready to take the inputs. A 0
>>>> + here indicates dcc is in a ready condition.
>>>> + Example:
>>>> + cat /sys/kernel/debug/dcc/.../ready
>>>> +
>>>> +What: /sys/kernel/debug/dcc/.../curr_list
>>> I still don't like the idea of having a single set of files to interface
>>> with all N lists. I think you should discover how many lists you have
>>> and create N directories of files, each on operating on a given list.
>> As explained before there cannot be different files based on lists as
>> the number of lists to be used varies across platforms where DCC is
>> used.
> Isn't this dcc->nr_link_list?
Yes. This varies across different SoCs and also user may not have access
to all the lists supported by DCC.
>
>> Also we are giving the user the flexibility to configure
>> multiple lists at one go whereas the dumps are collected in the form
>> of separate lists that are configured by the user.
>>
> I'm not sure I follow what you're trying to say here.
>
> If we determine that nr_link_list is 2, you create a directory named 0
> and one named 1, fill them with the interface files to operate on list 0
> and list 1 respectively. Then you still allow the user to configure and
> enable the 2 available lists?
>
> The difference is that it's clear how many lists you have and it's clear
> when you poke at 0/config_read that you're referring to the first list
> and poking 0/enable will mean the same list - there's no curr_list to
> mux between them in the interface.
So from DCC hardware perspective, it needs to be told that "list n
begins at x and ends at y". That is why the limitation of DCC
hardware is that the lists can only be configured sequentially and not
in a overlapping manner. So for example we need to enter
all the addresses to be stored for list n before jumping to any other
lists. Seeing this limitation, will it be advantageous to have
different set of files for different lists as we will be configuring
them sequentially anyway?
>
> Regards,
> Bjorn
>
>>>> +Date: March 2022
>>>> +Contact: Souradeep Chowdhury <[email protected]>
>>>> +Description:
>>>> + This attribute is used to enter the linklist to be
>>>> + used while appending addresses. The range of values
>>>> + for this is advertised either by a register or is
>>>> + predefined. Max value for this can be till 8.
>>>> + Example:
>>>> + echo 0 > /sys/kernel/debug/dcc/...curr_list
>>>> +
>>> Regards,
>>> Bjorn