LinuxLists.cc - [PATCH v4 0/5] ARM: Add GXP I2C Support

2023-01-25 18:47:22

Subject: [PATCH v4 0/5] ARM: Add GXP I2C Support

2023-01-25 18:47:24

Subject: [PATCH v4 1/5] i2c: hpe: Add GXP SoC I2C Controller

From: Nick Hawkins <[email protected]>

The GXP SoC supports 10 I2C engines. Each I2C engine is completely
independent and can function both as an I2C master and I2C slave. The
I2C master can operate in a multi master environment. The engines support
a scalable speed from 8kHZ to 1.5 Mhz.

Signed-off-by: Nick Hawkins <[email protected]>
Reviewed-by: Joel Stanley <[email protected]>

---

v4:
*Disable IRQ on device remove by register write
*Switch engine variable to u32
v3:
*Disable IRQ on device remove
*Remove use of I2C_CLASS_DEPRECATED
*Use i2c_parse_fw_timings instead of of_property_read_u32
*Remove redundant dev_err_probe as platform_get_irq already has one
*Used __iomem instead of res->start to find physical address
*Use BIT in gxp_i2c_irq_handler
*Made value u8 instead of u16
v2:
*Removed rogue tab in structure
*Removed use of __iomem base local variables as it was unnecessary
*Switched #if IS_ENABLED() -> if (IS_ENABLED()) inside functions
*Removed use of pr_* functions
*Removed informational prints in register and unregister functions
*Removed print from interrupt handler
*No informational prints in probe function
*Switched dev_err for dev_err_probe in probe function
*Use respective helper for mapping the resource to __iomem
---
drivers/i2c/busses/Kconfig | 7 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-gxp.c | 603 +++++++++++++++++++++++++++++++++++
3 files changed, 611 insertions(+)
create mode 100644 drivers/i2c/busses/i2c-gxp.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index e50f9603d189..8b3951e0ca5c 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1457,4 +1457,11 @@ config I2C_VIRTIO
This driver can also be built as a module. If so, the module
will be called i2c-virtio.

+config I2C_GXP
+ tristate "GXP I2C Interface"
+ depends on ARCH_HPE_GXP || COMPILE_TEST
+ help
+ This enables support for GXP I2C interface. The I2C engines can be
+ either I2C master or I2C slaves.
+
endmenu
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index e73cdb1d2b5a..dcc96eab6d68 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -127,6 +127,7 @@ obj-$(CONFIG_I2C_THUNDERX) += i2c-thunderx.o
obj-$(CONFIG_I2C_XILINX) += i2c-xiic.o
obj-$(CONFIG_I2C_XLP9XX) += i2c-xlp9xx.o
obj-$(CONFIG_I2C_RCAR) += i2c-rcar.o
+obj-$(CONFIG_I2C_GXP) += i2c-gxp.o

# External I2C/SMBus adapter drivers
obj-$(CONFIG_I2C_DIOLAN_U2C) += i2c-diolan-u2c.o
diff --git a/drivers/i2c/busses/i2c-gxp.c b/drivers/i2c/busses/i2c-gxp.c
new file mode 100644
index 000000000000..37272261ce8d
--- /dev/null
+++ b/drivers/i2c/busses/i2c-gxp.c
@@ -0,0 +1,603 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (C) 2022 Hewlett-Packard Enterprise Development Company, L.P. */
+
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/of_device.h>
+#include <linux/regmap.h>
+#include <linux/mfd/syscon.h>
+
+#define GXP_MAX_I2C_ENGINE 10
+static const char * const gxp_i2c_name[] = {
+ "gxp-i2c0", "gxp-i2c1", "gxp-i2c2", "gxp-i2c3",
+ "gxp-i2c4", "gxp-i2c5", "gxp-i2c6", "gxp-i2c7",
+ "gxp-i2c8", "gxp-i2c9" };
+
+/* GXP I2C Global interrupt status/enable register*/
+#define GXP_I2CINTSTAT 0x00
+#define GXP_I2CINTEN 0x04
+
+/* GXP I2C registers */
+#define GXP_I2CSTAT 0x00
+#define MASK_STOP_EVENT 0x20
+#define MASK_ACK 0x08
+#define MASK_RW 0x04
+#define GXP_I2CEVTERR 0x01
+#define MASK_SLAVE_CMD_EVENT 0x01
+#define MASK_SLAVE_DATA_EVENT 0x02
+#define MASK_MASTER_EVENT 0x10
+#define GXP_I2CSNPDAT 0x02
+#define GXP_I2CMCMD 0x04
+#define GXP_I2CSCMD 0x06
+#define GXP_I2CSNPAA 0x09
+#define GXP_I2CADVFEAT 0x0A
+#define GXP_I2COWNADR 0x0B
+#define GXP_I2CFREQDIV 0x0C
+#define GXP_I2CFLTFAIR 0x0D
+#define GXP_I2CTMOEDG 0x0E
+#define GXP_I2CCYCTIM 0x0F
+
+static bool i2c_global_init_done;
+
+enum {
+ GXP_I2C_IDLE = 0,
+ GXP_I2C_ADDR_PHASE,
+ GXP_I2C_RDATA_PHASE,
+ GXP_I2C_WDATA_PHASE,
+ GXP_I2C_ADDR_NACK,
+ GXP_I2C_DATA_NACK,
+ GXP_I2C_ERROR,
+ GXP_I2C_COMP
+};
+
+struct gxp_i2c_drvdata {
+ struct device *dev;
+ void __iomem *base;
+ struct i2c_timings t;
+ u32 engine;
+ int irq;
+ struct completion completion;
+ struct i2c_adapter adapter;
+ struct i2c_msg *curr_msg;
+ int msgs_remaining;
+ int msgs_num;
+ u8 *buf;
+ size_t buf_remaining;
+ unsigned char state;
+ struct i2c_client *slave;
+ unsigned char stopped;
+};
+
+static struct regmap *i2cg_map;
+
+static void gxp_i2c_start(struct gxp_i2c_drvdata *drvdata)
+{
+ u16 value;
+
+ drvdata->buf = drvdata->curr_msg->buf;
+ drvdata->buf_remaining = drvdata->curr_msg->len;
+
+ /* Note: Address in struct i2c_msg is 7 bits */
+ value = drvdata->curr_msg->addr << 9;
+
+ if (drvdata->curr_msg->flags & I2C_M_RD) {
+ /* Read */
+ value |= 0x05;
+ } else {
+ /* Write */
+ value |= 0x01;
+ }
+
+ drvdata->state = GXP_I2C_ADDR_PHASE;
+ writew(value, drvdata->base + GXP_I2CMCMD);
+}
+
+static int gxp_i2c_master_xfer(struct i2c_adapter *adapter,
+ struct i2c_msg *msgs, int num)
+{
+ int ret;
+ struct gxp_i2c_drvdata *drvdata = i2c_get_adapdata(adapter);
+ unsigned long time_left;
+
+ drvdata->msgs_remaining = num;
+ drvdata->curr_msg = msgs;
+ drvdata->msgs_num = num;
+ reinit_completion(&drvdata->completion);
+
+ gxp_i2c_start(drvdata);
+
+ time_left = wait_for_completion_timeout(&drvdata->completion,
+ adapter->timeout);
+ ret = num - drvdata->msgs_remaining;
+ if (time_left == 0) {
+ switch (drvdata->state) {
+ case GXP_I2C_WDATA_PHASE:
+ dev_err(drvdata->dev,
+ "gxp_i2c_start:write Data phase timeout at msg[%d]\n",
+ ret);
+ break;
+ case GXP_I2C_RDATA_PHASE:
+ dev_err(drvdata->dev,
+ "gxp_i2c_start:read Data phase timeout at msg[%d]\n",
+ ret);
+ break;
+ case GXP_I2C_ADDR_PHASE:
+ dev_err(drvdata->dev,
+ "gxp_i2c_start:Addr phase timeout\n");
+ break;
+ default:
+ dev_err(drvdata->dev,
+ "gxp_i2c_start:i2c transfer timeout state=%d\n",
+ drvdata->state);
+ break;
+ }
+ return -ETIMEDOUT;
+ }
+
+ if (drvdata->state == GXP_I2C_ADDR_NACK) {
+ dev_err(drvdata->dev,
+ "gxp_i2c_start:No ACK for address phase\n");
+ return -EIO;
+ } else if (drvdata->state == GXP_I2C_DATA_NACK) {
+ dev_err(drvdata->dev, "gxp_i2c_start:No ACK for data phase\n");
+ return -EIO;
+ }
+
+ return ret;
+}
+
+static u32 gxp_i2c_func(struct i2c_adapter *adap)
+{
+ if (IS_ENABLED(CONFIG_I2C_SLAVE))
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SLAVE;
+
+ return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
+}
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static int gxp_i2c_reg_slave(struct i2c_client *slave)
+{
+ struct gxp_i2c_drvdata *drvdata = i2c_get_adapdata(slave->adapter);
+
+ if (drvdata->slave)
+ return -EBUSY;
+
+ if (slave->flags & I2C_CLIENT_TEN)
+ return -EAFNOSUPPORT;
+
+ drvdata->slave = slave;
+
+ writeb(slave->addr << 1, drvdata->base + GXP_I2COWNADR);
+ writeb(0x69, drvdata->base + GXP_I2CSCMD);
+
+ return 0;
+}
+
+static int gxp_i2c_unreg_slave(struct i2c_client *slave)
+{
+ struct gxp_i2c_drvdata *drvdata = i2c_get_adapdata(slave->adapter);
+
+ WARN_ON(!drvdata->slave);
+
+ writeb(0x00, drvdata->base + GXP_I2COWNADR);
+ writeb(0xF0, drvdata->base + GXP_I2CSCMD);
+
+ drvdata->slave = NULL;
+
+ return 0;
+}
+#endif
+
+static const struct i2c_algorithm gxp_i2c_algo = {
+ .master_xfer = gxp_i2c_master_xfer,
+ .functionality = gxp_i2c_func,
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+ .reg_slave = gxp_i2c_reg_slave,
+ .unreg_slave = gxp_i2c_unreg_slave,
+#endif
+};
+
+static void gxp_i2c_stop(struct gxp_i2c_drvdata *drvdata)
+{
+ /* Clear event and send stop */
+ writeb(0x82, drvdata->base + GXP_I2CMCMD);
+
+ complete(&drvdata->completion);
+}
+
+static void gxp_i2c_restart(struct gxp_i2c_drvdata *drvdata)
+{
+ u16 value;
+
+ drvdata->buf = drvdata->curr_msg->buf;
+ drvdata->buf_remaining = drvdata->curr_msg->len;
+
+ value = drvdata->curr_msg->addr << 9;
+
+ if (drvdata->curr_msg->flags & I2C_M_RD) {
+ /* Read and clear master event */
+ value |= 0x85;
+ } else {
+ /* Write and clear master event */
+ value |= 0x81;
+ }
+
+ drvdata->state = GXP_I2C_ADDR_PHASE;
+
+ writew(value, drvdata->base + GXP_I2CMCMD);
+}
+
+static void gxp_i2c_chk_addr_ack(struct gxp_i2c_drvdata *drvdata)
+{
+ u16 value;
+
+ value = readb(drvdata->base + GXP_I2CSTAT);
+ if (!(value & MASK_ACK)) {
+ /* Got no ack, stop */
+ drvdata->state = GXP_I2C_ADDR_NACK;
+ gxp_i2c_stop(drvdata);
+ return;
+ }
+
+ if (drvdata->curr_msg->flags & I2C_M_RD) {
+ /* Start to read data from slave */
+ if (drvdata->buf_remaining == 0) {
+ /* No more data to read, stop */
+ drvdata->msgs_remaining--;
+ drvdata->state = GXP_I2C_COMP;
+ gxp_i2c_stop(drvdata);
+ return;
+ }
+ drvdata->state = GXP_I2C_RDATA_PHASE;
+
+ if (drvdata->buf_remaining == 1) {
+ /* The last data, do not ack */
+ writeb(0x84, drvdata->base + GXP_I2CMCMD);
+ } else {
+ /* Read data and ack it */
+ writeb(0x8C, drvdata->base + GXP_I2CMCMD);
+ }
+ } else {
+ /* Start to write first data to slave */
+ if (drvdata->buf_remaining == 0) {
+ /* No more data to write, stop */
+ drvdata->msgs_remaining--;
+ drvdata->state = GXP_I2C_COMP;
+ gxp_i2c_stop(drvdata);
+ return;
+ }
+ value = *drvdata->buf;
+ value = value << 8;
+ /* Clear master event */
+ value |= 0x80;
+ drvdata->buf++;
+ drvdata->buf_remaining--;
+ drvdata->state = GXP_I2C_WDATA_PHASE;
+ writew(value, drvdata->base + GXP_I2CMCMD);
+ }
+}
+
+static void gxp_i2c_ack_data(struct gxp_i2c_drvdata *drvdata)
+{
+ u8 value;
+
+ /* Store the data returned */
+ value = readb(drvdata->base + GXP_I2CSNPDAT);
+ *drvdata->buf = value;
+ drvdata->buf++;
+ drvdata->buf_remaining--;
+
+ if (drvdata->buf_remaining == 0) {
+ /* No more data, this message is completed. */
+ drvdata->msgs_remaining--;
+
+ if (drvdata->msgs_remaining == 0) {
+ /* No more messages, stop */
+ drvdata->state = GXP_I2C_COMP;
+ gxp_i2c_stop(drvdata);
+ return;
+ }
+ /* Move to next message and start transfer */
+ drvdata->curr_msg++;
+ gxp_i2c_restart(drvdata);
+ return;
+ }
+
+ /* Ack the slave to make it send next byte */
+ drvdata->state = GXP_I2C_RDATA_PHASE;
+ if (drvdata->buf_remaining == 1) {
+ /* The last data, do not ack */
+ writeb(0x84, drvdata->base + GXP_I2CMCMD);
+ } else {
+ /* Read data and ack it */
+ writeb(0x8C, drvdata->base + GXP_I2CMCMD);
+ }
+}
+
+static void gxp_i2c_chk_data_ack(struct gxp_i2c_drvdata *drvdata)
+{
+ u16 value;
+
+ value = readb(drvdata->base + GXP_I2CSTAT);
+ if (!(value & MASK_ACK)) {
+ /* Received No ack, stop */
+ drvdata->state = GXP_I2C_DATA_NACK;
+ gxp_i2c_stop(drvdata);
+ return;
+ }
+
+ /* Got ack, check if there is more data to write */
+ if (drvdata->buf_remaining == 0) {
+ /* No more data, this message is completed */
+ drvdata->msgs_remaining--;
+
+ if (drvdata->msgs_remaining == 0) {
+ /* No more messages, stop */
+ drvdata->state = GXP_I2C_COMP;
+ gxp_i2c_stop(drvdata);
+ return;
+ }
+ /* Move to next message and start transfer */
+ drvdata->curr_msg++;
+ gxp_i2c_restart(drvdata);
+ return;
+ }
+
+ /* Write data to slave */
+ value = *drvdata->buf;
+ value = value << 8;
+
+ /* Clear master event */
+ value |= 0x80;
+ drvdata->buf++;
+ drvdata->buf_remaining--;
+ drvdata->state = GXP_I2C_WDATA_PHASE;
+ writew(value, drvdata->base + GXP_I2CMCMD);
+}
+
+#if IS_ENABLED(CONFIG_I2C_SLAVE)
+static bool gxp_i2c_slave_irq_handler(struct gxp_i2c_drvdata *drvdata)
+{
+ u8 value;
+ u8 buf;
+ int ret;
+
+ value = readb(drvdata->base + GXP_I2CEVTERR);
+
+ /* Received start or stop event */
+ if (value & MASK_SLAVE_CMD_EVENT) {
+ value = readb(drvdata->base + GXP_I2CSTAT);
+ /* Master sent stop */
+ if (value & MASK_STOP_EVENT) {
+ if (drvdata->stopped == 0)
+ i2c_slave_event(drvdata->slave, I2C_SLAVE_STOP, &buf);
+ writeb(0x69, drvdata->base + GXP_I2CSCMD);
+ drvdata->stopped = 1;
+ } else {
+ /* Master sent start and wants to read */
+ drvdata->stopped = 0;
+ if (value & MASK_RW) {
+ i2c_slave_event(drvdata->slave,
+ I2C_SLAVE_READ_REQUESTED, &buf);
+ value = buf << 8 | 0x61;
+ writew(value, drvdata->base + GXP_I2CSCMD);
+ } else {
+ /* Master wants to write to us */
+ ret = i2c_slave_event(drvdata->slave,
+ I2C_SLAVE_WRITE_REQUESTED, &buf);
+ if (!ret) {
+ /* Ack next byte from master */
+ writeb(0x69, drvdata->base + GXP_I2CSCMD);
+ } else {
+ /* Nack next byte from master */
+ writeb(0x61, drvdata->base + GXP_I2CSCMD);
+ }
+ }
+ }
+ } else if (value & MASK_SLAVE_DATA_EVENT) {
+ value = readb(drvdata->base + GXP_I2CSTAT);
+ /* Master wants to read */
+ if (value & MASK_RW) {
+ /* Master wants another byte */
+ if (value & MASK_ACK) {
+ i2c_slave_event(drvdata->slave,
+ I2C_SLAVE_READ_PROCESSED, &buf);
+ value = buf << 8 | 0x61;
+ writew(value, drvdata->base + GXP_I2CSCMD);
+ } else {
+ /* No more bytes needed */
+ writew(0x69, drvdata->base + GXP_I2CSCMD);
+ }
+ } else {
+ /* Master wants to write to us */
+ value = readb(drvdata->base + GXP_I2CSNPDAT);
+ buf = (uint8_t)value;
+ ret = i2c_slave_event(drvdata->slave,
+ I2C_SLAVE_WRITE_RECEIVED, &buf);
+ if (!ret) {
+ /* Ack next byte from master */
+ writeb(0x69, drvdata->base + GXP_I2CSCMD);
+ } else {
+ /* Nack next byte from master */
+ writeb(0x61, drvdata->base + GXP_I2CSCMD);
+ }
+ }
+ } else {
+ return false;
+ }
+
+ return true;
+}
+#endif
+
+static irqreturn_t gxp_i2c_irq_handler(int irq, void *_drvdata)
+{
+ struct gxp_i2c_drvdata *drvdata = (struct gxp_i2c_drvdata *)_drvdata;
+ u32 value;
+
+ /* Check if the interrupt is for the current engine */
+ regmap_read(i2cg_map, GXP_I2CINTSTAT, &value);
+ if (!(value & BIT(drvdata->engine)))
+ return IRQ_NONE;
+
+ value = readb(drvdata->base + GXP_I2CEVTERR);
+
+ /* Error */
+ if (value & ~(MASK_MASTER_EVENT | MASK_SLAVE_CMD_EVENT |
+ MASK_SLAVE_DATA_EVENT)) {
+ /* Clear all events */
+ writeb(0x00, drvdata->base + GXP_I2CEVTERR);
+ drvdata->state = GXP_I2C_ERROR;
+ gxp_i2c_stop(drvdata);
+ return IRQ_HANDLED;
+ }
+
+ if (IS_ENABLED(CONFIG_I2C_SLAVE)) {
+ /* Slave mode */
+ if (value & (MASK_SLAVE_CMD_EVENT | MASK_SLAVE_DATA_EVENT)) {
+ if (gxp_i2c_slave_irq_handler(drvdata))
+ return IRQ_HANDLED;
+ return IRQ_NONE;
+ }
+ }
+
+ /* Master mode */
+ switch (drvdata->state) {
+ case GXP_I2C_ADDR_PHASE:
+ gxp_i2c_chk_addr_ack(drvdata);
+ break;
+
+ case GXP_I2C_RDATA_PHASE:
+ gxp_i2c_ack_data(drvdata);
+ break;
+
+ case GXP_I2C_WDATA_PHASE:
+ gxp_i2c_chk_data_ack(drvdata);
+ break;
+ }
+
+ return IRQ_HANDLED;
+}
+
+static void gxp_i2c_init(struct gxp_i2c_drvdata *drvdata)
+{
+ drvdata->state = GXP_I2C_IDLE;
+ writeb(2000000 / drvdata->t.bus_freq_hz,
+ drvdata->base + GXP_I2CFREQDIV);
+ writeb(0x32, drvdata->base + GXP_I2CFLTFAIR);
+ writeb(0x0a, drvdata->base + GXP_I2CTMOEDG);
+ writeb(0x00, drvdata->base + GXP_I2CCYCTIM);
+ writeb(0x00, drvdata->base + GXP_I2CSNPAA);
+ writeb(0x00, drvdata->base + GXP_I2CADVFEAT);
+ writeb(0xF0, drvdata->base + GXP_I2CSCMD);
+ writeb(0x80, drvdata->base + GXP_I2CMCMD);
+ writeb(0x00, drvdata->base + GXP_I2CEVTERR);
+ writeb(0x00, drvdata->base + GXP_I2COWNADR);
+}
+
+static int gxp_i2c_probe(struct platform_device *pdev)
+{
+ struct gxp_i2c_drvdata *drvdata;
+ int rc;
+ struct i2c_adapter *adapter;
+
+ if (!i2c_global_init_done) {
+ i2cg_map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
+ "hpe,sysreg");
+ if (IS_ERR(i2cg_map)) {
+ return dev_err_probe(&pdev->dev, IS_ERR(i2cg_map),
+ "failed to map i2cg_handle\n");
+ }
+
+ /* Disable interrupt */
+ regmap_update_bits(i2cg_map, GXP_I2CINTEN, 0x00000FFF, 0);
+ i2c_global_init_done = true;
+ }
+
+ drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata),
+ GFP_KERNEL);
+ if (!drvdata)
+ return -ENOMEM;
+
+ platform_set_drvdata(pdev, drvdata);
+ drvdata->dev = &pdev->dev;
+ init_completion(&drvdata->completion);
+
+ drvdata->base = devm_platform_ioremap_resource(pdev, 0);
+ if (IS_ERR(drvdata->base))
+ return PTR_ERR(drvdata->base);
+
+ /* Use physical memory address to determine which I2C engine this is. */
+ drvdata->engine = ((u32)drvdata->base & 0xf00) >> 8;
+
+ if (drvdata->engine >= GXP_MAX_I2C_ENGINE) {
+ return dev_err_probe(&pdev->dev, -EINVAL, "i2c engine% is unsupported\n",
+ drvdata->engine);
+ }
+
+ rc = platform_get_irq(pdev, 0);
+ if (rc < 0)
+ return rc;
+
+ drvdata->irq = rc;
+ rc = devm_request_irq(&pdev->dev, drvdata->irq, gxp_i2c_irq_handler,
+ IRQF_SHARED, gxp_i2c_name[drvdata->engine], drvdata);
+ if (rc < 0)
+ return dev_err_probe(&pdev->dev, rc, "irq request failed\n");
+
+ i2c_parse_fw_timings(&pdev->dev, &drvdata->t, true);
+
+ gxp_i2c_init(drvdata);
+
+ /* Enable interrupt */
+ regmap_update_bits(i2cg_map, GXP_I2CINTEN, BIT(drvdata->engine),
+ BIT(drvdata->engine));
+
+ adapter = &drvdata->adapter;
+ i2c_set_adapdata(adapter, drvdata);
+
+ adapter->owner = THIS_MODULE;
+ strscpy(adapter->name, "HPE GXP I2C adapter", sizeof(adapter->name));
+ adapter->algo = &gxp_i2c_algo;
+ adapter->dev.parent = &pdev->dev;
+ adapter->dev.of_node = pdev->dev.of_node;
+
+ rc = i2c_add_adapter(adapter);
+ if (rc)
+ return dev_err_probe(&pdev->dev, rc, "i2c add adapter failed\n");
+
+ return 0;
+}
+
+static int gxp_i2c_remove(struct platform_device *pdev)
+{
+ struct gxp_i2c_drvdata *drvdata = platform_get_drvdata(pdev);
+
+ /* Disable interrupt */
+ regmap_update_bits(i2cg_map, GXP_I2CINTEN, BIT(drvdata->engine), 0);
+ i2c_del_adapter(&drvdata->adapter);
+
+ return 0;
+}
+
+static const struct of_device_id gxp_i2c_of_match[] = {
+ { .compatible = "hpe,gxp-i2c" },
+ {},
+};
+MODULE_DEVICE_TABLE(of, gxp_i2c_of_match);
+
+static struct platform_driver gxp_i2c_driver = {
+ .probe = gxp_i2c_probe,
+ .remove = gxp_i2c_remove,
+ .driver = {
+ .name = "gxp-i2c",
+ .of_match_table = gxp_i2c_of_match,
+ },
+};
+module_platform_driver(gxp_i2c_driver);
+
+MODULE_AUTHOR("Nick Hawkins <[email protected]>");
+MODULE_DESCRIPTION("HPE GXP I2C bus driver");
+MODULE_LICENSE("GPL");
--
2.17.1

2023-02-15 20:29:19

by Wolfram Sang

[permalink] [raw]

Subject: Re: [PATCH v4 1/5] i2c: hpe: Add GXP SoC I2C Controller

Hi Nick,

> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index e50f9603d189..8b3951e0ca5c 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -1457,4 +1457,11 @@ config I2C_VIRTIO
> This driver can also be built as a module. If so, the module
> will be called i2c-virtio.
>
> +config I2C_GXP
> + tristate "GXP I2C Interface"
> + depends on ARCH_HPE_GXP || COMPILE_TEST
> + help
> + This enables support for GXP I2C interface. The I2C engines can be
> + either I2C master or I2C slaves.
> +

Shouldn't this be in the "I2C system bus drivers (mostly embedded /
system-on-chip)" section? (alphabetically sorted)

> +static bool i2c_global_init_done;

Can't we avoid this static by checking if i2cg_map is NULL/non-NULL?

> +
> +enum {
> + GXP_I2C_IDLE = 0,
> + GXP_I2C_ADDR_PHASE,
> + GXP_I2C_RDATA_PHASE,
> + GXP_I2C_WDATA_PHASE,
> + GXP_I2C_ADDR_NACK,
> + GXP_I2C_DATA_NACK,
> + GXP_I2C_ERROR,
> + GXP_I2C_COMP
> +};
> +
> +struct gxp_i2c_drvdata {
> + struct device *dev;
> + void __iomem *base;
> + struct i2c_timings t;
> + u32 engine;
> + int irq;
> + struct completion completion;
> + struct i2c_adapter adapter;
> + struct i2c_msg *curr_msg;
> + int msgs_remaining;
> + int msgs_num;
> + u8 *buf;
> + size_t buf_remaining;
> + unsigned char state;
> + struct i2c_client *slave;
> + unsigned char stopped;
> +};
> +
> +static struct regmap *i2cg_map;
> +
> +static void gxp_i2c_start(struct gxp_i2c_drvdata *drvdata)
> +{
> + u16 value;
> +
> + drvdata->buf = drvdata->curr_msg->buf;
> + drvdata->buf_remaining = drvdata->curr_msg->len;
> +
> + /* Note: Address in struct i2c_msg is 7 bits */
> + value = drvdata->curr_msg->addr << 9;
> +
> + if (drvdata->curr_msg->flags & I2C_M_RD) {
> + /* Read */
> + value |= 0x05;
> + } else {
> + /* Write */
> + value |= 0x01;
> + }

I'd write it more concise as:

value |= drvdata->curr_msg->flags & I2C_M_RD ? 0x05 : 0x01;

But this is a matter of taste.

> +
> + drvdata->state = GXP_I2C_ADDR_PHASE;
> + writew(value, drvdata->base + GXP_I2CMCMD);
> +}
> +
> +static int gxp_i2c_master_xfer(struct i2c_adapter *adapter,
> + struct i2c_msg *msgs, int num)
> +{
> + int ret;
> + struct gxp_i2c_drvdata *drvdata = i2c_get_adapdata(adapter);
> + unsigned long time_left;
> +
> + drvdata->msgs_remaining = num;
> + drvdata->curr_msg = msgs;
> + drvdata->msgs_num = num;
> + reinit_completion(&drvdata->completion);
> +
> + gxp_i2c_start(drvdata);
> +
> + time_left = wait_for_completion_timeout(&drvdata->completion,
> + adapter->timeout);
> + ret = num - drvdata->msgs_remaining;
> + if (time_left == 0) {
> + switch (drvdata->state) {
> + case GXP_I2C_WDATA_PHASE:
> + dev_err(drvdata->dev,
> + "gxp_i2c_start:write Data phase timeout at msg[%d]\n",
> + ret);

Please don't write error message to the log on timeouts. They can
happen. Think of an EEPROM which is busy because it needs to erase a
page. Upper layers need to handle this correctly, the user doesn't need
to know about it.

> + break;
> + case GXP_I2C_RDATA_PHASE:
> + dev_err(drvdata->dev,
> + "gxp_i2c_start:read Data phase timeout at msg[%d]\n",
> + ret);
> + break;
> + case GXP_I2C_ADDR_PHASE:
> + dev_err(drvdata->dev,
> + "gxp_i2c_start:Addr phase timeout\n");
> + break;
> + default:
> + dev_err(drvdata->dev,
> + "gxp_i2c_start:i2c transfer timeout state=%d\n",
> + drvdata->state);
> + break;
> + }
> + return -ETIMEDOUT;
> + }
> +
> + if (drvdata->state == GXP_I2C_ADDR_NACK) {
> + dev_err(drvdata->dev,
> + "gxp_i2c_start:No ACK for address phase\n");
> + return -EIO;
> + } else if (drvdata->state == GXP_I2C_DATA_NACK) {
> + dev_err(drvdata->dev, "gxp_i2c_start:No ACK for data phase\n");
> + return -EIO;

Same here for NACK. Otherwise i2cdetect will flood your logfile.

> + }
> +
> + return ret;
> +}
> +
> +static u32 gxp_i2c_func(struct i2c_adapter *adap)
> +{
> + if (IS_ENABLED(CONFIG_I2C_SLAVE))
> + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SLAVE;
> +
> + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
> +}
> +
> +#if IS_ENABLED(CONFIG_I2C_SLAVE)
> +static int gxp_i2c_reg_slave(struct i2c_client *slave)
> +{
> + struct gxp_i2c_drvdata *drvdata = i2c_get_adapdata(slave->adapter);
> +
> + if (drvdata->slave)
> + return -EBUSY;
> +
> + if (slave->flags & I2C_CLIENT_TEN)
> + return -EAFNOSUPPORT;
> +
> + drvdata->slave = slave;
> +
> + writeb(slave->addr << 1, drvdata->base + GXP_I2COWNADR);
> + writeb(0x69, drvdata->base + GXP_I2CSCMD);

Does it make sense to have #defines for the magic values for I2CSCMD?
BTW, is the datasheet public?

...

> +static void gxp_i2c_init(struct gxp_i2c_drvdata *drvdata)
> +{
> + drvdata->state = GXP_I2C_IDLE;
> + writeb(2000000 / drvdata->t.bus_freq_hz,
> + drvdata->base + GXP_I2CFREQDIV);
> + writeb(0x32, drvdata->base + GXP_I2CFLTFAIR);
> + writeb(0x0a, drvdata->base + GXP_I2CTMOEDG);
> + writeb(0x00, drvdata->base + GXP_I2CCYCTIM);
> + writeb(0x00, drvdata->base + GXP_I2CSNPAA);
> + writeb(0x00, drvdata->base + GXP_I2CADVFEAT);
> + writeb(0xF0, drvdata->base + GXP_I2CSCMD);
> + writeb(0x80, drvdata->base + GXP_I2CMCMD);
> + writeb(0x00, drvdata->base + GXP_I2CEVTERR);
> + writeb(0x00, drvdata->base + GXP_I2COWNADR);

Also here, lots of magic values. Can we do something about it?

> +}
> +
> +static int gxp_i2c_probe(struct platform_device *pdev)
> +{
> + struct gxp_i2c_drvdata *drvdata;
> + int rc;
> + struct i2c_adapter *adapter;
> +
> + if (!i2c_global_init_done) {
> + i2cg_map = syscon_regmap_lookup_by_phandle(pdev->dev.of_node,
> + "hpe,sysreg");
> + if (IS_ERR(i2cg_map)) {
> + return dev_err_probe(&pdev->dev, IS_ERR(i2cg_map),
> + "failed to map i2cg_handle\n");
> + }
> +
> + /* Disable interrupt */
> + regmap_update_bits(i2cg_map, GXP_I2CINTEN, 0x00000FFF, 0);
> + i2c_global_init_done = true;
> + }
> +
> + drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata),
> + GFP_KERNEL);
> + if (!drvdata)
> + return -ENOMEM;
> +
> + platform_set_drvdata(pdev, drvdata);
> + drvdata->dev = &pdev->dev;
> + init_completion(&drvdata->completion);
> +
> + drvdata->base = devm_platform_ioremap_resource(pdev, 0);
> + if (IS_ERR(drvdata->base))
> + return PTR_ERR(drvdata->base);
> +
> + /* Use physical memory address to determine which I2C engine this is. */
> + drvdata->engine = ((u32)drvdata->base & 0xf00) >> 8;

This breaks on my 64-bit test-build, so it will also fail with
COMPILE_TEST.

drivers/i2c/busses/i2c-gxp.c: In function ‘gxp_i2c_probe’:
drivers/i2c/busses/i2c-gxp.c:533:28: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
533 | drvdata->engine = ((u32)drvdata->base & 0xf00) >> 8;

The rest looks good to me.

Except for removing the hardcoded values, the other fixes should be
fairly simple, I think. So, hardcoded values could be changed
incrementally maybe. If this is possible at all. I still plan to have
this driver in 6.3.

Happy hacking,

Wolfram

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2023-02-16 20:03:24

by Hawkins, Nick

[permalink] [raw]

Subject: Re: [PATCH v4 1/5] i2c: hpe: Add GXP SoC I2C Controller

> Does it make sense to have #defines for the magic values for I2CSCMD?
> BTW, is the datasheet public?

I will work on the defines and get rid of all the magic values.
Unfortunately, there is no public spec available currently.
Hopefully, we will have one someday though.

> > + /* Use physical memory address to determine which I2C engine this is. */
> > + drvdata->engine = ((u32)drvdata->base & 0xf00) >> 8;

> This breaks on my 64-bit test-build, so it will also fail with
> COMPILE_TEST.

> drivers/i2c/busses/i2c-gxp.c: In function ‘gxp_i2c_probe’:
> drivers/i2c/busses/i2c-gxp.c:533:28: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
> 533 | drvdata->engine = ((u32)drvdata->base & 0xf00) >> 8;

I am currently unable to reproduce this error. I even set W=2.
Would replacing (u32) with (unsigned long) resolve it?

Thanks,

-Nick Hawkins

2023-02-16 20:47:42

by Wolfram Sang

[permalink] [raw]

Subject: Re: [PATCH v4 1/5] i2c: hpe: Add GXP SoC I2C Controller

Hi Nick,

> I will work on the defines and get rid of all the magic values.

Cool, thank you!

> Unfortunately, there is no public spec available currently.
> Hopefully, we will have one someday though.

Then, the #defines are even more helpful!

> > drivers/i2c/busses/i2c-gxp.c: In function ‘gxp_i2c_probe’:
> > drivers/i2c/busses/i2c-gxp.c:533:28: error: cast from pointer to integer of different size [-Werror=pointer-to-int-cast]
> > 533 | drvdata->engine = ((u32)drvdata->base & 0xf00) >> 8;
>
> I am currently unable to reproduce this error. I even set W=2.

Interesting. I have this version:

gcc (Debian 10.2.1-6) 10.2.1 20210110

> Would replacing (u32) with (unsigned long) resolve it?

Or size_t.

Happy hacking,

Wolfram

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