This series adds an algorithm for an I2C master physically located on an FSI
slave device. The I2C master has multiple ports, each of which may be connected
to an I2C slave. Access to the I2C master registers is achieved over FSI bus.
Due to the multi-port nature of the I2C master, the driver instantiates a new
I2C adapter for each port connected to a slave. The connected ports should be
defined in the device tree under the I2C master device.
Changes since v6
- Remove spinlock for reset functionality; it's unecessary and doesn't work
with the latest FSI core.
- Use a mutex instead of a semaphore, and don't wait for timeout to get the
lock.
- Use usleeps instead of schedule_timeout; it's not worth the overhead when
the wait should be very short in between sending the command and receiving
the response.
Changes since v5
- Fix reset functionality and do a reset after every transfer failure
Edward A. James (7):
dt-bindings: i2c: Add FSI-attached I2C master dt binding documentation
drivers/i2c: Add FSI-attached I2C master algorithm
drivers/i2c: Add port structure to FSI algorithm
drivers/i2c: Add abort and hardware reset procedures
drivers/i2c: Add transfer implementation for FSI algorithm
drivers/i2c: Add I2C master locking to FSI algorithm
drivers/i2c: Add bus recovery for FSI algorithm
Documentation/devicetree/bindings/i2c/i2c-fsi.txt | 40 ++
drivers/i2c/busses/Kconfig | 11 +
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-fsi.c | 738 ++++++++++++++++++++++
4 files changed, 790 insertions(+)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-fsi.txt
create mode 100644 drivers/i2c/busses/i2c-fsi.c
--
1.8.3.1
From: "Edward A. James" <[email protected]>
Add register definitions for FSI-attached I2C master and functions to
access those registers over FSI. Add an FSI driver so that our I2C bus
is probed up during an FSI scan.
Signed-off-by: Edward A. James <[email protected]>
---
drivers/i2c/busses/Kconfig | 11 ++
drivers/i2c/busses/Makefile | 1 +
drivers/i2c/busses/i2c-fsi.c | 244 +++++++++++++++++++++++++++++++++++++++++++
3 files changed, 256 insertions(+)
create mode 100644 drivers/i2c/busses/i2c-fsi.c
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 4f8df2e..ebba369 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1330,4 +1330,15 @@ config I2C_ZX2967
This driver can also be built as a module. If so, the module will be
called i2c-zx2967.
+config I2C_FSI
+ tristate "FSI I2C driver"
+ depends on FSI
+ help
+ Driver for FSI bus attached I2C masters. These are I2C masters that
+ are connected to the system over a FSI bus, instead of the more
+ common PCI or MMIO interface.
+
+ This driver can also be built as a module. If so, the module will be
+ called as i2c-fsi.
+
endmenu
diff --git a/drivers/i2c/busses/Makefile b/drivers/i2c/busses/Makefile
index 5a86914..4909fd6 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -137,5 +137,6 @@ obj-$(CONFIG_I2C_PCA_ISA) += i2c-pca-isa.o
obj-$(CONFIG_I2C_SIBYTE) += i2c-sibyte.o
obj-$(CONFIG_I2C_XGENE_SLIMPRO) += i2c-xgene-slimpro.o
obj-$(CONFIG_SCx200_ACB) += scx200_acb.o
+obj-$(CONFIG_I2C_FSI) += i2c-fsi.o
ccflags-$(CONFIG_I2C_DEBUG_BUS) := -DDEBUG
diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
new file mode 100644
index 0000000..79475f8
--- /dev/null
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -0,0 +1,244 @@
+/*
+ * Copyright 2017 IBM Corporation
+ *
+ * Eddie James <[email protected]>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version
+ * 2 of the License, or (at your option) any later version.
+ */
+
+#include <linux/device.h>
+#include <linux/errno.h>
+#include <linux/fsi.h>
+#include <linux/i2c.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+
+#define FSI_ENGID_I2C 0x7
+
+/* Find left shift from first set bit in m */
+#define MASK_TO_LSH(m) (__builtin_ffsll(m) - 1ULL)
+
+/* Extract field m from v */
+#define GETFIELD(m, v) (((v) & (m)) >> MASK_TO_LSH(m))
+
+/* Set field m of v to val */
+#define SETFIELD(m, v, val) \
+ (((v) & ~(m)) | ((((typeof(v))(val)) << MASK_TO_LSH(m)) & (m)))
+
+#define I2C_DEFAULT_CLK_DIV 6
+
+/* i2c registers */
+#define I2C_FSI_FIFO 0x00
+#define I2C_FSI_CMD 0x04
+#define I2C_FSI_MODE 0x08
+#define I2C_FSI_WATER_MARK 0x0C
+#define I2C_FSI_INT_MASK 0x10
+#define I2C_FSI_INT_COND 0x14
+#define I2C_FSI_OR_INT_MASK 0x14
+#define I2C_FSI_INTS 0x18
+#define I2C_FSI_AND_INT_MASK 0x18
+#define I2C_FSI_STAT 0x1C
+#define I2C_FSI_RESET_I2C 0x1C
+#define I2C_FSI_ESTAT 0x20
+#define I2C_FSI_RESET_ERR 0x20
+#define I2C_FSI_RESID_LEN 0x24
+#define I2C_FSI_SET_SCL 0x24
+#define I2C_FSI_PORT_BUSY 0x28
+#define I2C_FSI_RESET_SCL 0x2C
+#define I2C_FSI_SET_SDA 0x30
+#define I2C_FSI_RESET_SDA 0x34
+
+/* cmd register */
+#define I2C_CMD_WITH_START 0x80000000
+#define I2C_CMD_WITH_ADDR 0x40000000
+#define I2C_CMD_RD_CONT 0x20000000
+#define I2C_CMD_WITH_STOP 0x10000000
+#define I2C_CMD_FORCELAUNCH 0x08000000
+#define I2C_CMD_ADDR 0x00fe0000
+#define I2C_CMD_READ 0x00010000
+#define I2C_CMD_LEN 0x0000ffff
+
+/* mode register */
+#define I2C_MODE_CLKDIV 0xffff0000
+#define I2C_MODE_PORT 0x0000fc00
+#define I2C_MODE_ENHANCED 0x00000008
+#define I2C_MODE_DIAG 0x00000004
+#define I2C_MODE_PACE_ALLOW 0x00000002
+#define I2C_MODE_WRAP 0x00000001
+
+/* watermark register */
+#define I2C_WATERMARK_HI 0x0000f000
+#define I2C_WATERMARK_LO 0x000000f0
+
+#define I2C_FIFO_HI_LVL 4
+#define I2C_FIFO_LO_LVL 4
+
+/* interrupt register */
+#define I2C_INT_INV_CMD 0x00008000
+#define I2C_INT_PARITY 0x00004000
+#define I2C_INT_BE_OVERRUN 0x00002000
+#define I2C_INT_BE_ACCESS 0x00001000
+#define I2C_INT_LOST_ARB 0x00000800
+#define I2C_INT_NACK 0x00000400
+#define I2C_INT_DAT_REQ 0x00000200
+#define I2C_INT_CMD_COMP 0x00000100
+#define I2C_INT_STOP_ERR 0x00000080
+#define I2C_INT_BUSY 0x00000040
+#define I2C_INT_IDLE 0x00000020
+
+#define I2C_INT_ENABLE 0x0000ff80
+#define I2C_INT_ERR 0x0000fcc0
+
+/* status register */
+#define I2C_STAT_INV_CMD 0x80000000
+#define I2C_STAT_PARITY 0x40000000
+#define I2C_STAT_BE_OVERRUN 0x20000000
+#define I2C_STAT_BE_ACCESS 0x10000000
+#define I2C_STAT_LOST_ARB 0x08000000
+#define I2C_STAT_NACK 0x04000000
+#define I2C_STAT_DAT_REQ 0x02000000
+#define I2C_STAT_CMD_COMP 0x01000000
+#define I2C_STAT_STOP_ERR 0x00800000
+#define I2C_STAT_MAX_PORT 0x000f0000
+#define I2C_STAT_ANY_INT 0x00008000
+#define I2C_STAT_SCL_IN 0x00000800
+#define I2C_STAT_SDA_IN 0x00000400
+#define I2C_STAT_PORT_BUSY 0x00000200
+#define I2C_STAT_SELF_BUSY 0x00000100
+#define I2C_STAT_FIFO_COUNT 0x000000ff
+
+#define I2C_STAT_ERR 0xfc800000
+#define I2C_STAT_ANY_RESP 0xff800000
+
+/* extended status register */
+#define I2C_ESTAT_FIFO_SZ 0xff000000
+#define I2C_ESTAT_SCL_IN_SY 0x00008000
+#define I2C_ESTAT_SDA_IN_SY 0x00004000
+#define I2C_ESTAT_S_SCL 0x00002000
+#define I2C_ESTAT_S_SDA 0x00001000
+#define I2C_ESTAT_M_SCL 0x00000800
+#define I2C_ESTAT_M_SDA 0x00000400
+#define I2C_ESTAT_HI_WATER 0x00000200
+#define I2C_ESTAT_LO_WATER 0x00000100
+#define I2C_ESTAT_PORT_BUSY 0x00000080
+#define I2C_ESTAT_SELF_BUSY 0x00000040
+#define I2C_ESTAT_VERSION 0x0000001f
+
+struct fsi_i2c_master {
+ struct fsi_device *fsi;
+ u8 fifo_size;
+};
+
+static int fsi_i2c_read_reg(struct fsi_device *fsi, unsigned int reg,
+ u32 *data)
+{
+ int rc;
+ __be32 data_be;
+
+ rc = fsi_device_read(fsi, reg, &data_be, sizeof(data_be));
+ if (rc)
+ return rc;
+
+ *data = be32_to_cpu(data_be);
+
+ return 0;
+}
+
+static int fsi_i2c_write_reg(struct fsi_device *fsi, unsigned int reg,
+ u32 *data)
+{
+ __be32 data_be = cpu_to_be32(*data);
+
+ return fsi_device_write(fsi, reg, &data_be, sizeof(data_be));
+}
+
+static int fsi_i2c_dev_init(struct fsi_i2c_master *i2c)
+{
+ int rc;
+ u32 mode = I2C_MODE_ENHANCED, extended_status, watermark = 0;
+ u32 interrupt = 0;
+
+ /* since we use polling, disable interrupts */
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_INT_MASK, &interrupt);
+ if (rc)
+ return rc;
+
+ mode = SETFIELD(I2C_MODE_CLKDIV, mode, I2C_DEFAULT_CLK_DIV);
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_ESTAT, &extended_status);
+ if (rc)
+ return rc;
+
+ i2c->fifo_size = GETFIELD(I2C_ESTAT_FIFO_SZ, extended_status);
+ watermark = SETFIELD(I2C_WATERMARK_HI, watermark,
+ i2c->fifo_size - I2C_FIFO_HI_LVL);
+ watermark = SETFIELD(I2C_WATERMARK_LO, watermark,
+ I2C_FIFO_LO_LVL);
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_WATER_MARK, &watermark);
+
+ return rc;
+}
+
+static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
+ int num)
+{
+ return -EOPNOTSUPP;
+}
+
+static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
+{
+ return I2C_FUNC_I2C | I2C_FUNC_PROTOCOL_MANGLING | I2C_FUNC_10BIT_ADDR
+ | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
+}
+
+static const struct i2c_algorithm fsi_i2c_algorithm = {
+ .master_xfer = fsi_i2c_xfer,
+ .functionality = fsi_i2c_functionality,
+};
+
+static int fsi_i2c_probe(struct device *dev)
+{
+ struct fsi_i2c_master *i2c;
+ int rc;
+
+ i2c = devm_kzalloc(dev, sizeof(*i2c), GFP_KERNEL);
+ if (!i2c)
+ return -ENOMEM;
+
+ i2c->fsi = to_fsi_dev(dev);
+
+ rc = fsi_i2c_dev_init(i2c);
+ if (rc)
+ return rc;
+
+ dev_set_drvdata(dev, i2c);
+
+ return 0;
+}
+
+static const struct fsi_device_id fsi_i2c_ids[] = {
+ { FSI_ENGID_I2C, FSI_VERSION_ANY },
+ { 0 }
+};
+
+static struct fsi_driver fsi_i2c_driver = {
+ .id_table = fsi_i2c_ids,
+ .drv = {
+ .name = "i2c-fsi",
+ .bus = &fsi_bus_type,
+ .probe = fsi_i2c_probe,
+ },
+};
+
+module_fsi_driver(fsi_i2c_driver);
+
+MODULE_AUTHOR("Eddie James <[email protected]>");
+MODULE_DESCRIPTION("FSI attached I2C master");
+MODULE_LICENSE("GPL");
--
1.8.3.1
From: "Edward A. James" <[email protected]>
Since there are many ports per master, each with it's own adapter and
chardev, we need some locking to prevent transfers from changing the
master state while other transfers are in progress.
Signed-off-by: Edward A. James <[email protected]>
---
drivers/i2c/busses/i2c-fsi.c | 16 ++++++++++++----
1 file changed, 12 insertions(+), 4 deletions(-)
diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 78e3586..f309267 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -18,6 +18,7 @@
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
+#include <linux/mutex.h>
#include <linux/of.h>
#define FSI_ENGID_I2C 0x7
@@ -143,6 +144,7 @@ struct fsi_i2c_master {
struct fsi_device *fsi;
u8 fifo_size;
struct list_head ports;
+ struct mutex lock;
};
struct fsi_i2c_port {
@@ -585,11 +587,14 @@ static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int i, rc;
unsigned long start_time;
struct fsi_i2c_port *port = adap->algo_data;
+ struct fsi_i2c_master *master = port->master;
struct i2c_msg *msg;
+ mutex_lock(&master->lock);
+
rc = fsi_i2c_set_port(port);
if (rc)
- return rc;
+ goto unlock;
for (i = 0; i < num; ++i) {
msg = msgs + i;
@@ -597,15 +602,17 @@ static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
rc = fsi_i2c_start(port, msg, i == num - 1);
if (rc)
- return rc;
+ goto unlock;
rc = fsi_i2c_wait(port, msg,
adap->timeout - (jiffies - start_time));
if (rc)
- return rc;
+ goto unlock;
}
- return 0;
+unlock:
+ mutex_unlock(&master->lock);
+ return rc;
}
static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
@@ -631,6 +638,7 @@ static int fsi_i2c_probe(struct device *dev)
if (!i2c)
return -ENOMEM;
+ mutex_init(&i2c->lock);
i2c->fsi = to_fsi_dev(dev);
INIT_LIST_HEAD(&i2c->ports);
--
1.8.3.1
From: "Edward A. James" <[email protected]>
Add and initialize I2C adapters for each port on the FSI-attached I2C
master. Ports for each master are defined in the devicetree.
Signed-off-by: Edward A. James <[email protected]>
---
drivers/i2c/busses/i2c-fsi.c | 96 ++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 96 insertions(+)
diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 79475f8..4ad5d68 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -14,7 +14,9 @@
#include <linux/fsi.h>
#include <linux/i2c.h>
#include <linux/kernel.h>
+#include <linux/list.h>
#include <linux/module.h>
+#include <linux/of.h>
#define FSI_ENGID_I2C 0x7
@@ -130,6 +132,14 @@
struct fsi_i2c_master {
struct fsi_device *fsi;
u8 fifo_size;
+ struct list_head ports;
+};
+
+struct fsi_i2c_port {
+ struct list_head list;
+ struct i2c_adapter adapter;
+ struct fsi_i2c_master *master;
+ u16 port;
};
static int fsi_i2c_read_reg(struct fsi_device *fsi, unsigned int reg,
@@ -186,9 +196,44 @@ static int fsi_i2c_dev_init(struct fsi_i2c_master *i2c)
return rc;
}
+static int fsi_i2c_set_port(struct fsi_i2c_port *port)
+{
+ int rc;
+ struct fsi_device *fsi = port->master->fsi;
+ u32 mode, dummy = 0;
+ u16 old_port;
+
+ rc = fsi_i2c_read_reg(fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ return rc;
+
+ old_port = GETFIELD(I2C_MODE_PORT, mode);
+
+ if (old_port != port->port) {
+ mode = SETFIELD(I2C_MODE_PORT, mode, port->port);
+ rc = fsi_i2c_write_reg(fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ return rc;
+
+ /* reset engine when port is changed */
+ rc = fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
+ if (rc)
+ return rc;
+ }
+
+ return rc;
+}
+
static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
+ int rc;
+ struct fsi_i2c_port *port = adap->algo_data;
+
+ rc = fsi_i2c_set_port(port);
+ if (rc)
+ return rc;
+
return -EOPNOTSUPP;
}
@@ -206,23 +251,73 @@ static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
static int fsi_i2c_probe(struct device *dev)
{
struct fsi_i2c_master *i2c;
+ struct fsi_i2c_port *port;
+ struct device_node *np;
int rc;
+ u32 port_no;
i2c = devm_kzalloc(dev, sizeof(*i2c), GFP_KERNEL);
if (!i2c)
return -ENOMEM;
i2c->fsi = to_fsi_dev(dev);
+ INIT_LIST_HEAD(&i2c->ports);
rc = fsi_i2c_dev_init(i2c);
if (rc)
return rc;
+ /* Add adapter for each i2c port of the master. */
+ for_each_available_child_of_node(dev->of_node, np) {
+ rc = of_property_read_u32(np, "reg", &port_no);
+ if (rc || port_no > USHRT_MAX)
+ continue;
+
+ port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
+ if (!port)
+ break;
+
+ port->master = i2c;
+ port->port = port_no;
+
+ port->adapter.owner = THIS_MODULE;
+ port->adapter.dev.of_node = np;
+ port->adapter.dev.parent = dev;
+ port->adapter.algo = &fsi_i2c_algorithm;
+ port->adapter.algo_data = port;
+
+ snprintf(port->adapter.name, sizeof(port->adapter.name),
+ "i2c_bus-%u", port_no);
+
+ rc = i2c_add_adapter(&port->adapter);
+ if (rc < 0) {
+ dev_err(dev, "Failed to register adapter: %d\n", rc);
+ devm_kfree(dev, port);
+ continue;
+ }
+
+ list_add(&port->list, &i2c->ports);
+ }
+
dev_set_drvdata(dev, i2c);
return 0;
}
+static int fsi_i2c_remove(struct device *dev)
+{
+ struct fsi_i2c_master *i2c = dev_get_drvdata(dev);
+ struct fsi_i2c_port *port;
+
+ if (!list_empty(&i2c->ports)) {
+ list_for_each_entry(port, &i2c->ports, list) {
+ i2c_del_adapter(&port->adapter);
+ }
+ }
+
+ return 0;
+}
+
static const struct fsi_device_id fsi_i2c_ids[] = {
{ FSI_ENGID_I2C, FSI_VERSION_ANY },
{ 0 }
@@ -234,6 +329,7 @@ static int fsi_i2c_probe(struct device *dev)
.name = "i2c-fsi",
.bus = &fsi_bus_type,
.probe = fsi_i2c_probe,
+ .remove = fsi_i2c_remove,
},
};
--
1.8.3.1
From: "Edward A. James" <[email protected]>
Bus recovery should reset the engine and force clock the bus 9 times
to recover most situations.
Signed-off-by: Edward A. James <[email protected]>
---
drivers/i2c/busses/i2c-fsi.c | 19 +++++++++++++++++++
1 file changed, 19 insertions(+)
diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index f309267..52a662c 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -621,6 +621,24 @@ static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
| I2C_FUNC_SMBUS_EMUL | I2C_FUNC_SMBUS_BLOCK_DATA;
}
+static int fsi_i2c_recover_bus(struct i2c_adapter *adap)
+{
+ int rc;
+ struct fsi_i2c_port *port = adap->algo_data;
+ struct fsi_i2c_master *master = port->master;
+
+ mutex_lock(&master->lock);
+
+ rc = fsi_i2c_reset(master, port->port);
+
+ mutex_unlock(&master->lock);
+ return rc;
+}
+
+static struct i2c_bus_recovery_info fsi_i2c_bus_recovery_info = {
+ .recover_bus = fsi_i2c_recover_bus,
+};
+
static const struct i2c_algorithm fsi_i2c_algorithm = {
.master_xfer = fsi_i2c_xfer,
.functionality = fsi_i2c_functionality,
@@ -663,6 +681,7 @@ static int fsi_i2c_probe(struct device *dev)
port->adapter.dev.of_node = np;
port->adapter.dev.parent = dev;
port->adapter.algo = &fsi_i2c_algorithm;
+ port->adapter.bus_recovery_info = &fsi_i2c_bus_recovery_info;
port->adapter.algo_data = port;
snprintf(port->adapter.name, sizeof(port->adapter.name),
--
1.8.3.1
From: "Edward A. James" <[email protected]>
Add abort procedure for failed transfers. Add engine and bus reset
procedures to recover from as many faults as possible.
Signed-off-by: Edward A. James <[email protected]>
---
drivers/i2c/busses/i2c-fsi.c | 172 +++++++++++++++++++++++++++++++++++++++++++
1 file changed, 172 insertions(+)
diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 4ad5d68..c0b17df 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -9,10 +9,12 @@
* 2 of the License, or (at your option) any later version.
*/
+#include <linux/delay.h>
#include <linux/device.h>
#include <linux/errno.h>
#include <linux/fsi.h>
#include <linux/i2c.h>
+#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
@@ -129,6 +131,14 @@
#define I2C_ESTAT_SELF_BUSY 0x00000040
#define I2C_ESTAT_VERSION 0x0000001f
+#define I2C_PORT_BUSY_RESET 0x80000000
+
+#define I2C_LOCAL_SLEEP_MAX_US 500
+#define I2C_LOCAL_SLEEP_MIN_US 50
+
+/* choose timeout length from legacy driver; it's well tested */
+#define I2C_ABORT_TIMEOUT msecs_to_jiffies(100)
+
struct fsi_i2c_master {
struct fsi_device *fsi;
u8 fifo_size;
@@ -224,6 +234,168 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
return rc;
}
+static int fsi_i2c_reset_bus(struct fsi_i2c_master *i2c)
+{
+ int i, rc;
+ u32 mode, stat, ext, dummy = 0;
+
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ return rc;
+
+ mode |= I2C_MODE_DIAG;
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ return rc;
+
+ for (i = 0; i < 9; ++i) {
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
+ if (rc)
+ return rc;
+ }
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SDA, &dummy);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SDA, &dummy);
+ if (rc)
+ return rc;
+
+ mode &= ~I2C_MODE_DIAG;
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
+ if (rc)
+ return rc;
+
+ /* check for hardware fault */
+ if (!(stat & I2C_STAT_SCL_IN) || !(stat & I2C_STAT_SDA_IN)) {
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_ESTAT, &ext);
+ if (rc)
+ return rc;
+
+ dev_err(&i2c->fsi->dev, "bus stuck status[%08X] ext[%08X]\n",
+ stat, ext);
+ }
+
+ return 0;
+}
+
+static int fsi_i2c_reset(struct fsi_i2c_master *i2c, u16 port)
+{
+ int rc;
+ u32 mode, stat, dummy = 0;
+
+ /* reset engine */
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+ if (rc)
+ return rc;
+
+ /* re-init engine */
+ rc = fsi_i2c_dev_init(i2c);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ return rc;
+
+ /* set port; default after reset is 0 */
+ if (port) {
+ mode = SETFIELD(I2C_MODE_PORT, mode, port);
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+ if (rc)
+ return rc;
+ }
+
+ /* reset busy register; hw workaround */
+ dummy = I2C_PORT_BUSY_RESET;
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_PORT_BUSY, &dummy);
+ if (rc)
+ return rc;
+
+ /* force bus reset */
+ rc = fsi_i2c_reset_bus(i2c);
+ if (rc)
+ return rc;
+
+ /* reset errors */
+ dummy = 0;
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+ if (rc)
+ return rc;
+
+ /* wait for command complete; time from legacy driver */
+ msleep(1);
+
+ rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
+ if (rc)
+ return rc;
+
+ if (stat & I2C_STAT_CMD_COMP)
+ return rc;
+
+ /* failed to get command complete; reset engine again */
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+ if (rc)
+ return rc;
+
+ /* re-init engine again */
+ return fsi_i2c_dev_init(i2c);
+}
+
+static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)
+{
+ int rc;
+ unsigned long start;
+ u32 cmd = I2C_CMD_WITH_STOP;
+ struct fsi_device *fsi = port->master->fsi;
+
+ rc = fsi_i2c_reset(port->master, port->port);
+ if (rc)
+ return rc;
+
+ /* skip final stop command for these errors */
+ if (status & (I2C_STAT_PARITY | I2C_STAT_LOST_ARB | I2C_STAT_STOP_ERR))
+ return 0;
+
+ /* write stop command */
+ rc = fsi_i2c_write_reg(fsi, I2C_FSI_CMD, &cmd);
+ if (rc)
+ return rc;
+
+ /* wait until we see command complete in the master */
+ start = jiffies;
+
+ do {
+ rc = fsi_i2c_read_reg(fsi, I2C_FSI_STAT, &status);
+ if (rc)
+ return rc;
+
+ if (status & I2C_STAT_CMD_COMP)
+ return 0;
+
+ usleep_range(I2C_LOCAL_SLEEP_MIN_US, I2C_LOCAL_SLEEP_MAX_US);
+ } while (time_after(start + I2C_ABORT_TIMEOUT, jiffies));
+
+ return -ETIME;
+}
+
static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
--
1.8.3.1
From: "Edward A. James" <[email protected]>
Execute I2C transfers from the FSI-attached I2C master. Use polling
instead of interrupts as we have no hardware IRQ over FSI.
Signed-off-by: Edward A. James <[email protected]>
---
drivers/i2c/busses/i2c-fsi.c | 203 ++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 201 insertions(+), 2 deletions(-)
diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index c0b17df..78e3586 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -150,6 +150,7 @@ struct fsi_i2c_port {
struct i2c_adapter adapter;
struct fsi_i2c_master *master;
u16 port;
+ u16 xfrd;
};
static int fsi_i2c_read_reg(struct fsi_device *fsi, unsigned int reg,
@@ -234,6 +235,103 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
return rc;
}
+static int fsi_i2c_start(struct fsi_i2c_port *port, struct i2c_msg *msg,
+ bool stop)
+{
+ int rc;
+ struct fsi_i2c_master *i2c = port->master;
+ u32 cmd = I2C_CMD_WITH_START | I2C_CMD_WITH_ADDR;
+
+ port->xfrd = 0;
+
+ if (msg->flags & I2C_M_RD)
+ cmd |= I2C_CMD_READ;
+
+ if (stop || msg->flags & I2C_M_STOP)
+ cmd |= I2C_CMD_WITH_STOP;
+
+ cmd = SETFIELD(I2C_CMD_ADDR, cmd, msg->addr >> 1);
+ cmd = SETFIELD(I2C_CMD_LEN, cmd, msg->len);
+
+ rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_CMD, &cmd);
+
+ return rc;
+}
+
+static int fsi_i2c_write_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
+ u8 fifo_count)
+{
+ int write;
+ int rc = 0;
+ struct fsi_i2c_master *i2c = port->master;
+ int bytes_to_write = i2c->fifo_size - fifo_count;
+ int bytes_remaining = msg->len - port->xfrd;
+
+ if (bytes_to_write > bytes_remaining)
+ bytes_to_write = bytes_remaining;
+
+ while (bytes_to_write > 0) {
+ write = bytes_to_write;
+ /* fsi limited to max 4 byte aligned ops */
+ if (bytes_to_write > 4)
+ write = 4;
+ else if (write == 3)
+ write = 2;
+
+ rc = fsi_device_write(i2c->fsi, I2C_FSI_FIFO,
+ &msg->buf[port->xfrd], write);
+ if (rc)
+ return rc;
+
+ port->xfrd += write;
+ bytes_to_write -= write;
+ }
+
+ return rc;
+}
+
+static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
+ u8 fifo_count)
+{
+ int read;
+ int rc = 0;
+ struct fsi_i2c_master *i2c = port->master;
+ int xfr_remaining = msg->len - port->xfrd;
+ u32 dummy;
+
+ while (fifo_count) {
+ read = fifo_count;
+ /* fsi limited to max 4 byte aligned ops */
+ if (fifo_count > 4)
+ read = 4;
+ else if (read == 3)
+ read = 2;
+
+ if (xfr_remaining) {
+ if (xfr_remaining < read)
+ read = xfr_remaining;
+
+ rc = fsi_device_read(i2c->fsi, I2C_FSI_FIFO,
+ &msg->buf[port->xfrd], read);
+ if (rc)
+ return rc;
+
+ port->xfrd += read;
+ xfr_remaining -= read;
+ } else {
+ /* no more buffer but data in fifo, need to clear it */
+ rc = fsi_device_read(i2c->fsi, I2C_FSI_FIFO, &dummy,
+ read);
+ if (rc)
+ return rc;
+ }
+
+ fifo_count -= read;
+ }
+
+ return rc;
+}
+
static int fsi_i2c_reset_bus(struct fsi_i2c_master *i2c)
{
int i, rc;
@@ -396,17 +494,118 @@ static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)
return -ETIME;
}
+static int fsi_i2c_handle_status(struct fsi_i2c_port *port,
+ struct i2c_msg *msg, u32 status)
+{
+ int rc;
+ u8 fifo_count;
+
+ if (status & I2C_STAT_ERR) {
+ rc = fsi_i2c_abort(port, status);
+ if (rc)
+ return rc;
+
+ if (status & I2C_STAT_INV_CMD)
+ return -EINVAL;
+
+ if (status & (I2C_STAT_PARITY | I2C_STAT_BE_OVERRUN |
+ I2C_STAT_BE_ACCESS))
+ return -EPROTO;
+
+ if (status & I2C_STAT_NACK)
+ return -ENXIO;
+
+ if (status & I2C_STAT_LOST_ARB)
+ return -EAGAIN;
+
+ if (status & I2C_STAT_STOP_ERR)
+ return -EBADMSG;
+
+ return -EIO;
+ }
+
+ if (status & I2C_STAT_DAT_REQ) {
+ fifo_count = GETFIELD(I2C_STAT_FIFO_COUNT, status);
+
+ if (msg->flags & I2C_M_RD)
+ rc = fsi_i2c_read_fifo(port, msg, fifo_count);
+ else
+ rc = fsi_i2c_write_fifo(port, msg, fifo_count);
+
+ return rc;
+ }
+
+ if (status & I2C_STAT_CMD_COMP) {
+ if (port->xfrd < msg->len)
+ rc = -ENODATA;
+ else
+ rc = msg->len;
+
+ return rc;
+ }
+
+ return 0;
+}
+
+static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
+ unsigned long timeout)
+{
+ u32 status = 0;
+ int rc;
+ unsigned long start = jiffies;
+
+ do {
+ rc = fsi_i2c_read_reg(port->master->fsi, I2C_FSI_STAT,
+ &status);
+ if (rc)
+ return rc;
+
+ if (status & I2C_STAT_ANY_RESP) {
+ rc = fsi_i2c_handle_status(port, msg, status);
+ if (rc < 0)
+ return rc;
+
+ /* cmd complete and all data xfrd */
+ if (rc == msg->len)
+ return 0;
+
+ /* need to xfr more data, but maybe don't need wait */
+ continue;
+ }
+
+ usleep_range(I2C_LOCAL_SLEEP_MIN_US, I2C_LOCAL_SLEEP_MAX_US);
+ } while (time_after(start + timeout, jiffies));
+
+ return -ETIME;
+}
+
static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
int num)
{
- int rc;
+ int i, rc;
+ unsigned long start_time;
struct fsi_i2c_port *port = adap->algo_data;
+ struct i2c_msg *msg;
rc = fsi_i2c_set_port(port);
if (rc)
return rc;
- return -EOPNOTSUPP;
+ for (i = 0; i < num; ++i) {
+ msg = msgs + i;
+ start_time = jiffies;
+
+ rc = fsi_i2c_start(port, msg, i == num - 1);
+ if (rc)
+ return rc;
+
+ rc = fsi_i2c_wait(port, msg,
+ adap->timeout - (jiffies - start_time));
+ if (rc)
+ return rc;
+ }
+
+ return 0;
}
static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
--
1.8.3.1
From: "Edward A. James" <[email protected]>
Document the bindings.
Signed-off-by: Edward A. James <[email protected]>
Acked-by: Rob Herring <[email protected]>
---
Documentation/devicetree/bindings/i2c/i2c-fsi.txt | 40 +++++++++++++++++++++++
1 file changed, 40 insertions(+)
create mode 100644 Documentation/devicetree/bindings/i2c/i2c-fsi.txt
diff --git a/Documentation/devicetree/bindings/i2c/i2c-fsi.txt b/Documentation/devicetree/bindings/i2c/i2c-fsi.txt
new file mode 100644
index 0000000..b1be2ce
--- /dev/null
+++ b/Documentation/devicetree/bindings/i2c/i2c-fsi.txt
@@ -0,0 +1,40 @@
+Device-tree bindings for FSI-attached I2C master and busses
+-----------------------------------------------------------
+
+Required properties:
+ - compatible = "ibm,i2c-fsi";
+ - reg = < address size >; : The FSI CFAM address and address
+ space size.
+ - #address-cells = <1>; : Number of address cells in child
+ nodes.
+ - #size-cells = <0>; : Number of size cells in child nodes.
+ - child nodes : Nodes to describe busses off the I2C
+ master.
+
+Child node required properties:
+ - reg = < port number > : The port number on the I2C master.
+
+Child node optional properties:
+ - child nodes : Nodes to describe devices on the I2C
+ bus.
+
+Examples:
+
+ i2c@1800 {
+ compatible = "ibm,i2c-fsi";
+ reg = < 0x1800 0x400 >;
+ #address-cells = <1>;
+ #size-cells = <0>;
+
+ i2c-bus@0 {
+ reg = <0>;
+ };
+
+ i2c-bus@1 {
+ reg = <1>;
+
+ eeprom@50 {
+ compatible = "vendor,dev-name";
+ };
+ };
+ };
--
1.8.3.1
On Wed, May 30, 2018 at 1:24 AM, Eddie James <[email protected]> wrote:
> From: "Edward A. James" <[email protected]>
>
> Add and initialize I2C adapters for each port on the FSI-attached I2C
> master. Ports for each master are defined in the devicetree.
> +#include <linux/of.h>
> +static int fsi_i2c_set_port(struct fsi_i2c_port *port)
> +{
> + int rc;
> + struct fsi_device *fsi = port->master->fsi;
> + u32 mode, dummy = 0;
> + u16 old_port;
> +
> + rc = fsi_i2c_read_reg(fsi, I2C_FSI_MODE, &mode);
> + if (rc)
> + return rc;
> +
> + old_port = GETFIELD(I2C_MODE_PORT, mode);
> +
> + if (old_port != port->port) {
Why not simple
if (port->port == GETFIELD())
return 0;
?
> + /* reset engine when port is changed */
> + rc = fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
> + if (rc)
> + return rc;
> + }
> + return rc;
It's hardly would be non-zero, right?
> +}
> static int fsi_i2c_probe(struct device *dev)
> {
Isn't below somehow repeats of_i2c_register_devices() ?
Why not to use it?
> + /* Add adapter for each i2c port of the master. */
> + for_each_available_child_of_node(dev->of_node, np) {
> + rc = of_property_read_u32(np, "reg", &port_no);
> + if (rc || port_no > USHRT_MAX)
> + continue;
> +
> + port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
> + if (!port)
> + break;
> +
> + port->master = i2c;
> + port->port = port_no;
> +
> + port->adapter.owner = THIS_MODULE;
> + port->adapter.dev.of_node = np;
> + port->adapter.dev.parent = dev;
> + port->adapter.algo = &fsi_i2c_algorithm;
> + port->adapter.algo_data = port;
> +
> + snprintf(port->adapter.name, sizeof(port->adapter.name),
> + "i2c_bus-%u", port_no);
> +
> + rc = i2c_add_adapter(&port->adapter);
> + if (rc < 0) {
> + dev_err(dev, "Failed to register adapter: %d\n", rc);
> + devm_kfree(dev, port);
This hurts my eyes. Why?!
> + continue;
> + }
> +
> + list_add(&port->list, &i2c->ports);
> + }
> +
> dev_set_drvdata(dev, i2c);
>
> return 0;
> }
> + if (!list_empty(&i2c->ports)) {
My gosh, this is done already in list_for_each*()
> + list_for_each_entry(port, &i2c->ports, list) {
> + i2c_del_adapter(&port->adapter);
> + }
> + }
--
With Best Regards,
Andy Shevchenko
On 05/29/2018 03:24 PM, Eddie James wrote:
> diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
> index 4f8df2e..ebba369 100644
> --- a/drivers/i2c/busses/Kconfig
> +++ b/drivers/i2c/busses/Kconfig
> @@ -1330,4 +1330,15 @@ config I2C_ZX2967
> This driver can also be built as a module. If so, the module will be
> called i2c-zx2967.
>
> +config I2C_FSI
> + tristate "FSI I2C driver"
> + depends on FSI
> + help
> + Driver for FSI bus attached I2C masters. These are I2C masters that
> + are connected to the system over a FSI bus, instead of the more
over an FSI bus,
> + common PCI or MMIO interface.
> +
> + This driver can also be built as a module. If so, the module will be
> + called as i2c-fsi.
> +
> endmenu
--
~Randy
On Wed, May 30, 2018 at 1:24 AM, Eddie James <[email protected]> wrote:
> From: "Edward A. James" <[email protected]>
>
> Add register definitions for FSI-attached I2C master and functions to
> access those registers over FSI. Add an FSI driver so that our I2C bus
> is probed up during an FSI scan.
This looks like reinventing a wheel in some ways.
See my comments below.
> +/*
> + * Copyright 2017 IBM Corporation
> + *
> + * Eddie James <[email protected]>
> + *
> + * This program is free software; you can redistribute it and/or
> + * modify it under the terms of the GNU General Public License
> + * as published by the Free Software Foundation; either version
> + * 2 of the License, or (at your option) any later version.
> + */
We are using SPDX identifiers. Can you?
> +/* Find left shift from first set bit in m */
> +#define MASK_TO_LSH(m) (__builtin_ffsll(m) - 1ULL)
Oh. What about GENMASK()?
> +/* Extract field m from v */
> +#define GETFIELD(m, v) (((v) & (m)) >> MASK_TO_LSH(m))
> +
> +/* Set field m of v to val */
> +#define SETFIELD(m, v, val) \
> + (((v) & ~(m)) | ((((typeof(v))(val)) << MASK_TO_LSH(m)) & (m)))
Oh, what about https://elixir.bootlin.com/linux/latest/source/include/linux/bitfield.h
?
> +#define I2C_CMD_WITH_START 0x80000000
> +#define I2C_CMD_WITH_ADDR 0x40000000
> +#define I2C_CMD_RD_CONT 0x20000000
> +#define I2C_CMD_WITH_STOP 0x10000000
> +#define I2C_CMD_FORCELAUNCH 0x08000000
BIT() ?
> +#define I2C_CMD_ADDR 0x00fe0000
> +#define I2C_CMD_READ 0x00010000
GENMASK()? Though precisely here it might be good to leave explicit values.
> +#define I2C_CMD_LEN 0x0000ffff
> +#define I2C_MODE_CLKDIV 0xffff0000
> +#define I2C_MODE_PORT 0x0000fc00
> +#define I2C_MODE_ENHANCED 0x00000008
> +#define I2C_MODE_DIAG 0x00000004
> +#define I2C_MODE_PACE_ALLOW 0x00000002
> +#define I2C_MODE_WRAP 0x00000001
What are they? Masks? Bit fields? Just plain numbers?
> +#define I2C_WATERMARK_HI 0x0000f000
> +#define I2C_WATERMARK_LO 0x000000f0
GENMASK() ?
> +#define I2C_INT_INV_CMD 0x00008000
> +#define I2C_INT_PARITY 0x00004000
> +#define I2C_INT_BE_OVERRUN 0x00002000
> +#define I2C_INT_BE_ACCESS 0x00001000
> +#define I2C_INT_LOST_ARB 0x00000800
> +#define I2C_INT_NACK 0x00000400
> +#define I2C_INT_DAT_REQ 0x00000200
> +#define I2C_INT_CMD_COMP 0x00000100
> +#define I2C_INT_STOP_ERR 0x00000080
> +#define I2C_INT_BUSY 0x00000040
> +#define I2C_INT_IDLE 0x00000020
BIT()
> +#define I2C_INT_ENABLE 0x0000ff80
> +#define I2C_INT_ERR 0x0000fcc0
> +#define I2C_STAT_INV_CMD 0x80000000
> +#define I2C_STAT_PARITY 0x40000000
> +#define I2C_STAT_BE_OVERRUN 0x20000000
> +#define I2C_STAT_BE_ACCESS 0x10000000
> +#define I2C_STAT_LOST_ARB 0x08000000
> +#define I2C_STAT_NACK 0x04000000
> +#define I2C_STAT_DAT_REQ 0x02000000
> +#define I2C_STAT_CMD_COMP 0x01000000
> +#define I2C_STAT_STOP_ERR 0x00800000
> +#define I2C_STAT_MAX_PORT 0x000f0000
> +#define I2C_STAT_ANY_INT 0x00008000
> +#define I2C_STAT_SCL_IN 0x00000800
> +#define I2C_STAT_SDA_IN 0x00000400
> +#define I2C_STAT_PORT_BUSY 0x00000200
> +#define I2C_STAT_SELF_BUSY 0x00000100
BIT()
> +#define I2C_STAT_FIFO_COUNT 0x000000ff
GENMASK()
> +
> +#define I2C_STAT_ERR 0xfc800000
> +#define I2C_STAT_ANY_RESP 0xff800000
> +#define I2C_ESTAT_FIFO_SZ 0xff000000
GENMASK()
> +#define I2C_ESTAT_SCL_IN_SY 0x00008000
> +#define I2C_ESTAT_SDA_IN_SY 0x00004000
> +#define I2C_ESTAT_S_SCL 0x00002000
> +#define I2C_ESTAT_S_SDA 0x00001000
> +#define I2C_ESTAT_M_SCL 0x00000800
> +#define I2C_ESTAT_M_SDA 0x00000400
> +#define I2C_ESTAT_HI_WATER 0x00000200
> +#define I2C_ESTAT_LO_WATER 0x00000100
> +#define I2C_ESTAT_PORT_BUSY 0x00000080
> +#define I2C_ESTAT_SELF_BUSY 0x00000040
BIT()
> +#define I2C_ESTAT_VERSION 0x0000001f
GENMASK()
> + __be32 data_be;
No need to have a suffix. If anything can go wrong we have a tool,
it's called sparse. It will catch out inappropriate use of __bitwise
types.
> + __be32 data_be = cpu_to_be32(*data);
cpu_to_be32p() IIUC?
> +static int fsi_i2c_dev_init(struct fsi_i2c_master *i2c)
> +{
> + int rc;
> + u32 mode = I2C_MODE_ENHANCED, extended_status, watermark = 0;
> + u32 interrupt = 0;
Redundant assignment.
> +
> + /* since we use polling, disable interrupts */
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_INT_MASK, &interrupt);
> + if (rc)
> + return rc;
> + return rc;
Would be non-zero?
> +}
--
With Best Regards,
Andy Shevchenko
On Wed, May 30, 2018 at 1:24 AM, Eddie James <[email protected]> wrote:
> From: "Edward A. James" <[email protected]>
>
> Execute I2C transfers from the FSI-attached I2C master. Use polling
> instead of interrupts as we have no hardware IRQ over FSI.
> + if (msg->flags & I2C_M_RD)
> + cmd |= I2C_CMD_READ;
I think we have a helper for this, though not sure.
> +static int fsi_i2c_write_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
> + u8 fifo_count)
> +{
> + int write;
> + int rc = 0;
Redundant assignment.
> + struct fsi_i2c_master *i2c = port->master;
> + int bytes_to_write = i2c->fifo_size - fifo_count;
> + int bytes_remaining = msg->len - port->xfrd;
> + if (bytes_to_write > bytes_remaining)
> + bytes_to_write = bytes_remaining;
_write = min(_write, _remaining);
> + while (bytes_to_write > 0) {
> + write = bytes_to_write;
> + /* fsi limited to max 4 byte aligned ops */
> + if (bytes_to_write > 4)
> + write = 4;
> + else if (write == 3)
> + write = 2;
write = min_t(int, 4, rounddown_pow_of_two(bytes_to_write));
Also check it carefully, it might be optimized even more, though I
didn't think much.
> + }
> + return rc;
How it can be non-zero?
> +}
> +
> +static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
> + u8 fifo_count)
> +{
> + int read;
> + int rc = 0;
Redundant assignment.
> + struct fsi_i2c_master *i2c = port->master;
> + int xfr_remaining = msg->len - port->xfrd;
> + u32 dummy;
> +
> + while (fifo_count) {
> + read = fifo_count;
> + /* fsi limited to max 4 byte aligned ops */
> + if (fifo_count > 4)
> + read = 4;
> + else if (read == 3)
> + read = 2;
See above for write case and do in similar way.
> +
> + if (xfr_remaining) {
> + if (xfr_remaining < read)
> + read = xfr_remaining;
read = min(read, _remaining);
> +
> + rc = fsi_device_read(i2c->fsi, I2C_FSI_FIFO,
> + &msg->buf[port->xfrd], read);
> + if (rc)
> + return rc;
> +
> + port->xfrd += read;
> + xfr_remaining -= read;
> + } else {
> + /* no more buffer but data in fifo, need to clear it */
> + rc = fsi_device_read(i2c->fsi, I2C_FSI_FIFO, &dummy,
> + read);
> + if (rc)
> + return rc;
> + }
> +
> + fifo_count -= read;
> + }
> +
> + return rc;
How non-zero possible here?
> +}
> + if (port->xfrd < msg->len)
> + rc = -ENODATA;
> + else
> + rc = msg->len;
> +
> + return rc;
if (...)
return -ENODATA;
return msg->len;
?
> + u32 status = 0;
Redundant assignment.
> + return -ETIME;
ETIMEDOUT ?
--
With Best Regards,
Andy Shevchenko
On Wed, May 30, 2018 at 1:24 AM, Eddie James <[email protected]> wrote:
> From: "Edward A. James" <[email protected]>
>
> Add abort procedure for failed transfers. Add engine and bus reset
> procedures to recover from as many faults as possible.
> +#define I2C_PORT_BUSY_RESET 0x80000000
BIT() ?
> + for (i = 0; i < 9; ++i) {
i++ would work as well.
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
> + if (rc)
> + return rc;
> +
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
> + if (rc)
> + return rc;
> + }
> + /* reset errors */
> + dummy = 0;
> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
> + if (rc)
> + return rc;
Ah, okay, discard my previous comments on dummy assignments. It seems
input and output.
> + msleep(1);
msleep(1) usually a bad idea.
usleep_range() I guess what you need here.
> +}
> + return -ETIME;
ETIMEDOUT ?
--
With Best Regards,
Andy Shevchenko
On 05/29/2018 06:42 PM, Andy Shevchenko wrote:
> On Wed, May 30, 2018 at 1:24 AM, Eddie James <[email protected]> wrote:
>> From: "Edward A. James" <[email protected]>
>>
>> Add register definitions for FSI-attached I2C master and functions to
>> access those registers over FSI. Add an FSI driver so that our I2C bus
>> is probed up during an FSI scan.
> This looks like reinventing a wheel in some ways.
>
> See my comments below.
>
>> +/*
>> + * Copyright 2017 IBM Corporation
>> + *
>> + * Eddie James <[email protected]>
>> + *
>> + * This program is free software; you can redistribute it and/or
>> + * modify it under the terms of the GNU General Public License
>> + * as published by the Free Software Foundation; either version
>> + * 2 of the License, or (at your option) any later version.
>> + */
> We are using SPDX identifiers. Can you?
Sure.
>
>> +/* Find left shift from first set bit in m */
>> +#define MASK_TO_LSH(m) (__builtin_ffsll(m) - 1ULL)
> Oh. What about GENMASK()?
>
>> +/* Extract field m from v */
>> +#define GETFIELD(m, v) (((v) & (m)) >> MASK_TO_LSH(m))
>> +
>> +/* Set field m of v to val */
>> +#define SETFIELD(m, v, val) \
>> + (((v) & ~(m)) | ((((typeof(v))(val)) << MASK_TO_LSH(m)) & (m)))
> Oh, what about https://elixir.bootlin.com/linux/latest/source/include/linux/bitfield.h
> ?
Good idea, thanks.
>
>> +#define I2C_CMD_WITH_START 0x80000000
>> +#define I2C_CMD_WITH_ADDR 0x40000000
>> +#define I2C_CMD_RD_CONT 0x20000000
>> +#define I2C_CMD_WITH_STOP 0x10000000
>> +#define I2C_CMD_FORCELAUNCH 0x08000000
> BIT() ?
>
>> +#define I2C_CMD_ADDR 0x00fe0000
>> +#define I2C_CMD_READ 0x00010000
> GENMASK()? Though precisely here it might be good to leave explicit values.
>
>> +#define I2C_CMD_LEN 0x0000ffff
>> +#define I2C_MODE_CLKDIV 0xffff0000
>> +#define I2C_MODE_PORT 0x0000fc00
>> +#define I2C_MODE_ENHANCED 0x00000008
>> +#define I2C_MODE_DIAG 0x00000004
>> +#define I2C_MODE_PACE_ALLOW 0x00000002
>> +#define I2C_MODE_WRAP 0x00000001
> What are they? Masks? Bit fields? Just plain numbers?
>
>> +#define I2C_WATERMARK_HI 0x0000f000
>> +#define I2C_WATERMARK_LO 0x000000f0
> GENMASK() ?
>
>> +#define I2C_INT_INV_CMD 0x00008000
>> +#define I2C_INT_PARITY 0x00004000
>> +#define I2C_INT_BE_OVERRUN 0x00002000
>> +#define I2C_INT_BE_ACCESS 0x00001000
>> +#define I2C_INT_LOST_ARB 0x00000800
>> +#define I2C_INT_NACK 0x00000400
>> +#define I2C_INT_DAT_REQ 0x00000200
>> +#define I2C_INT_CMD_COMP 0x00000100
>> +#define I2C_INT_STOP_ERR 0x00000080
>> +#define I2C_INT_BUSY 0x00000040
>> +#define I2C_INT_IDLE 0x00000020
> BIT()
>
>> +#define I2C_INT_ENABLE 0x0000ff80
>> +#define I2C_INT_ERR 0x0000fcc0
>> +#define I2C_STAT_INV_CMD 0x80000000
>> +#define I2C_STAT_PARITY 0x40000000
>> +#define I2C_STAT_BE_OVERRUN 0x20000000
>> +#define I2C_STAT_BE_ACCESS 0x10000000
>> +#define I2C_STAT_LOST_ARB 0x08000000
>> +#define I2C_STAT_NACK 0x04000000
>> +#define I2C_STAT_DAT_REQ 0x02000000
>> +#define I2C_STAT_CMD_COMP 0x01000000
>> +#define I2C_STAT_STOP_ERR 0x00800000
>> +#define I2C_STAT_MAX_PORT 0x000f0000
>> +#define I2C_STAT_ANY_INT 0x00008000
>> +#define I2C_STAT_SCL_IN 0x00000800
>> +#define I2C_STAT_SDA_IN 0x00000400
>> +#define I2C_STAT_PORT_BUSY 0x00000200
>> +#define I2C_STAT_SELF_BUSY 0x00000100
> BIT()
>
>> +#define I2C_STAT_FIFO_COUNT 0x000000ff
> GENMASK()
>
>> +
>> +#define I2C_STAT_ERR 0xfc800000
>> +#define I2C_STAT_ANY_RESP 0xff800000
>> +#define I2C_ESTAT_FIFO_SZ 0xff000000
> GENMASK()
>
>> +#define I2C_ESTAT_SCL_IN_SY 0x00008000
>> +#define I2C_ESTAT_SDA_IN_SY 0x00004000
>> +#define I2C_ESTAT_S_SCL 0x00002000
>> +#define I2C_ESTAT_S_SDA 0x00001000
>> +#define I2C_ESTAT_M_SCL 0x00000800
>> +#define I2C_ESTAT_M_SDA 0x00000400
>> +#define I2C_ESTAT_HI_WATER 0x00000200
>> +#define I2C_ESTAT_LO_WATER 0x00000100
>> +#define I2C_ESTAT_PORT_BUSY 0x00000080
>> +#define I2C_ESTAT_SELF_BUSY 0x00000040
> BIT()
>
>> +#define I2C_ESTAT_VERSION 0x0000001f
> GENMASK()
>
>> + __be32 data_be;
> No need to have a suffix. If anything can go wrong we have a tool,
> it's called sparse. It will catch out inappropriate use of __bitwise
> types.
I already have a variable called data...
>
>> + __be32 data_be = cpu_to_be32(*data);
> cpu_to_be32p() IIUC?
Sure.
>
>> +static int fsi_i2c_dev_init(struct fsi_i2c_master *i2c)
>> +{
>> + int rc;
>> + u32 mode = I2C_MODE_ENHANCED, extended_status, watermark = 0;
>> + u32 interrupt = 0;
> Redundant assignment.
No, I need to set the interrupt register to 0, so I must set this.
>
>> +
>> + /* since we use polling, disable interrupts */
>> + rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_INT_MASK, &interrupt);
>> + if (rc)
>> + return rc;
>> + return rc;
> Would be non-zero?
No, fsi_i2c_write_reg returns non-zero on error, zero on success. That
is what I want.
Thanks,
Eddie
>
>> +}
On 05/29/2018 06:19 PM, Andy Shevchenko wrote:
> On Wed, May 30, 2018 at 1:24 AM, Eddie James <[email protected]> wrote:
>> From: "Edward A. James" <[email protected]>
>>
>> Add and initialize I2C adapters for each port on the FSI-attached I2C
>> master. Ports for each master are defined in the devicetree.
>> +#include <linux/of.h>
>
>> +static int fsi_i2c_set_port(struct fsi_i2c_port *port)
>> +{
>> + int rc;
>> + struct fsi_device *fsi = port->master->fsi;
>> + u32 mode, dummy = 0;
>> + u16 old_port;
>> +
>> + rc = fsi_i2c_read_reg(fsi, I2C_FSI_MODE, &mode);
>> + if (rc)
>> + return rc;
>> +
>> + old_port = GETFIELD(I2C_MODE_PORT, mode);
>> +
>> + if (old_port != port->port) {
> Why not simple
>
> if (port->port == GETFIELD())
> return 0;
>
> ?
Sure.
>
>> + /* reset engine when port is changed */
>> + rc = fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
>> + if (rc)
>> + return rc;
>> + }
>> + return rc;
> It's hardly would be non-zero, right?
No, fsi_i2c_read_reg and fsi_i2c_write_reg both return 0 on success and
non-zero on error. That is the desired behavior of this function also.
>
>> +}
>> static int fsi_i2c_probe(struct device *dev)
>> {
> Isn't below somehow repeats of_i2c_register_devices() ?
> Why not to use it?
Because I need to assign all these port structure fields. Also looks
like of_i2c_register_devices creates new devices; I just want an adapter
for each port.
>
>> + /* Add adapter for each i2c port of the master. */
>> + for_each_available_child_of_node(dev->of_node, np) {
>> + rc = of_property_read_u32(np, "reg", &port_no);
>> + if (rc || port_no > USHRT_MAX)
>> + continue;
>> +
>> + port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
>> + if (!port)
>> + break;
>> +
>> + port->master = i2c;
>> + port->port = port_no;
>> +
>> + port->adapter.owner = THIS_MODULE;
>> + port->adapter.dev.of_node = np;
>> + port->adapter.dev.parent = dev;
>> + port->adapter.algo = &fsi_i2c_algorithm;
>> + port->adapter.algo_data = port;
>> +
>> + snprintf(port->adapter.name, sizeof(port->adapter.name),
>> + "i2c_bus-%u", port_no);
>> +
>> + rc = i2c_add_adapter(&port->adapter);
>> + if (rc < 0) {
>> + dev_err(dev, "Failed to register adapter: %d\n", rc);
>> + devm_kfree(dev, port);
> This hurts my eyes. Why?!
What would you suggest instead?
>
>> + continue;
>> + }
>> +
>> + list_add(&port->list, &i2c->ports);
>> + }
>> +
>> dev_set_drvdata(dev, i2c);
>>
>> return 0;
>> }
>> + if (!list_empty(&i2c->ports)) {
> My gosh, this is done already in list_for_each*()
No, list_for_each_entry does NOT check if the list is empty or if the
first entry is NULL.
Thanks,
Eddie
>
>> + list_for_each_entry(port, &i2c->ports, list) {
>> + i2c_del_adapter(&port->adapter);
>> + }
>> + }
>
>
On 05/29/2018 06:19 PM, Andy Shevchenko wrote:
> On Wed, May 30, 2018 at 1:24 AM, Eddie James <[email protected]> wrote:
>> From: "Edward A. James" <[email protected]>
>>
>> Add and initialize I2C adapters for each port on the FSI-attached I2C
>> master. Ports for each master are defined in the devicetree.
>> +#include <linux/of.h>
>
>> +static int fsi_i2c_set_port(struct fsi_i2c_port *port)
>> +{
>> + int rc;
>> + struct fsi_device *fsi = port->master->fsi;
>> + u32 mode, dummy = 0;
>> + u16 old_port;
>> +
>> + rc = fsi_i2c_read_reg(fsi, I2C_FSI_MODE, &mode);
>> + if (rc)
>> + return rc;
>> +
>> + old_port = GETFIELD(I2C_MODE_PORT, mode);
>> +
>> + if (old_port != port->port) {
> Why not simple
>
> if (port->port == GETFIELD())
> return 0;
>
> ?
>
>> + /* reset engine when port is changed */
>> + rc = fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
>> + if (rc)
>> + return rc;
>> + }
>> + return rc;
> It's hardly would be non-zero, right?
Sorry, misunderstood your comment here. You are correct, it can only be
zero.
Thanks,
Eddie
>
>> +}
>> static int fsi_i2c_probe(struct device *dev)
>> {
> Isn't below somehow repeats of_i2c_register_devices() ?
> Why not to use it?
>
>> + /* Add adapter for each i2c port of the master. */
>> + for_each_available_child_of_node(dev->of_node, np) {
>> + rc = of_property_read_u32(np, "reg", &port_no);
>> + if (rc || port_no > USHRT_MAX)
>> + continue;
>> +
>> + port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
>> + if (!port)
>> + break;
>> +
>> + port->master = i2c;
>> + port->port = port_no;
>> +
>> + port->adapter.owner = THIS_MODULE;
>> + port->adapter.dev.of_node = np;
>> + port->adapter.dev.parent = dev;
>> + port->adapter.algo = &fsi_i2c_algorithm;
>> + port->adapter.algo_data = port;
>> +
>> + snprintf(port->adapter.name, sizeof(port->adapter.name),
>> + "i2c_bus-%u", port_no);
>> +
>> + rc = i2c_add_adapter(&port->adapter);
>> + if (rc < 0) {
>> + dev_err(dev, "Failed to register adapter: %d\n", rc);
>> + devm_kfree(dev, port);
> This hurts my eyes. Why?!
>
>> + continue;
>> + }
>> +
>> + list_add(&port->list, &i2c->ports);
>> + }
>> +
>> dev_set_drvdata(dev, i2c);
>>
>> return 0;
>> }
>> + if (!list_empty(&i2c->ports)) {
> My gosh, this is done already in list_for_each*()
>
>> + list_for_each_entry(port, &i2c->ports, list) {
>> + i2c_del_adapter(&port->adapter);
>> + }
>> + }
>
>
On 05/29/2018 07:08 PM, Andy Shevchenko wrote:
> On Wed, May 30, 2018 at 1:24 AM, Eddie James <[email protected]> wrote:
>> From: "Edward A. James" <[email protected]>
>>
>> Execute I2C transfers from the FSI-attached I2C master. Use polling
>> instead of interrupts as we have no hardware IRQ over FSI.
>> + if (msg->flags & I2C_M_RD)
>> + cmd |= I2C_CMD_READ;
> I think we have a helper for this, though not sure.
Didn't see any other I2C drivers using any helper for msg->flags.
>
>> +static int fsi_i2c_write_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
>> + u8 fifo_count)
>> +{
>> + int write;
>> + int rc = 0;
> Redundant assignment.
>
>> + struct fsi_i2c_master *i2c = port->master;
>> + int bytes_to_write = i2c->fifo_size - fifo_count;
>> + int bytes_remaining = msg->len - port->xfrd;
>> + if (bytes_to_write > bytes_remaining)
>> + bytes_to_write = bytes_remaining;
> _write = min(_write, _remaining);
>
>> + while (bytes_to_write > 0) {
>> + write = bytes_to_write;
>> + /* fsi limited to max 4 byte aligned ops */
>> + if (bytes_to_write > 4)
>> + write = 4;
>> + else if (write == 3)
>> + write = 2;
> write = min_t(int, 4, rounddown_pow_of_two(bytes_to_write));
>
> Also check it carefully, it might be optimized even more, though I
> didn't think much.
I think it is more readable this way, and I'm not convinced the
min(rounddown()) is faster. I did however add a common function to do
this check since it's performed in both the read and write fifo
functions. Let me know what you think on v8.
Thanks,
Eddie
On Wed, 2018-05-30 at 10:47 -0500, Eddie James wrote:
> > > + if (!list_empty(&i2c->ports)) {
> >
> > My gosh, this is done already in list_for_each*()
>
> No, list_for_each_entry does NOT check if the list is empty or if the
> first entry is NULL.
NULL is never valid for a list. It does however check for an empty list
It does it implicitely in the test part of the for () statement,
checking if the next pointer points back to the head.
Cheers,
Ben.
On Wed, May 30, 2018 at 6:47 PM, Eddie James <[email protected]> wrote:
> On 05/29/2018 06:19 PM, Andy Shevchenko wrote:
>> On Wed, May 30, 2018 at 1:24 AM, Eddie James <[email protected]>
>> wrote:
>>> static int fsi_i2c_probe(struct device *dev)
>>> {
>>
>> Isn't below somehow repeats of_i2c_register_devices() ?
>> Why not to use it?
>
>
> Because I need to assign all these port structure fields. Also looks like
> of_i2c_register_devices creates new devices; I just want an adapter for each
> port.
Hmm... Wolfram, what is your opinion on this design?
>>> + devm_kfree(dev, port);
>>
>> This hurts my eyes. Why?!
> What would you suggest instead?
You even didn't wait for answer, why to ask then?
Moreover, you didn't answer to my question. Why are you doing that
call implicitly?
>>> + if (!list_empty(&i2c->ports)) {
>>
>> My gosh, this is done already in list_for_each*()
> No, list_for_each_entry does NOT check if the list is empty or if the first
> entry is NULL.
Please, read the macro source code again.
--
With Best Regards,
Andy Shevchenko
On Thu, May 31, 2018 at 12:27 AM, Andy Shevchenko
<[email protected]> wrote:
> On Wed, May 30, 2018 at 6:47 PM, Eddie James <[email protected]> wrote:
>> On 05/29/2018 06:19 PM, Andy Shevchenko wrote:
>>>> + devm_kfree(dev, port);
>>> This hurts my eyes. Why?!
>
>> What would you suggest instead?
> Why are you doing that
> call implicitly?
s/implicitly/explicitly/
--
With Best Regards,
Andy Shevchenko
On Thu, 2018-05-31 at 00:27 +0300, Andy Shevchenko wrote:
> On Wed, May 30, 2018 at 6:47 PM, Eddie James <[email protected]> wrote:
> > On 05/29/2018 06:19 PM, Andy Shevchenko wrote:
> > > On Wed, May 30, 2018 at 1:24 AM, Eddie James <[email protected]>
> > > wrote:
> > > > static int fsi_i2c_probe(struct device *dev)
> > > > {
> > >
> > > Isn't below somehow repeats of_i2c_register_devices() ?
> > > Why not to use it?
> >
> >
> > Because I need to assign all these port structure fields. Also looks like
> > of_i2c_register_devices creates new devices; I just want an adapter for each
> > port.
>
> Hmm... Wolfram, what is your opinion on this design?
Andy, I don't understand your issue.
of_i2c_register_devices() is about discovering the i2c devices below a
given bus. This is not what is happening here.
This is a driver for a master that supports multiple busses, so it the
above loop creates all the busses.
> > > > + devm_kfree(dev, port);
> > >
> > > This hurts my eyes. Why?!
> > What would you suggest instead?
>
> You even didn't wait for answer, why to ask then?
Please stop being so rude.
> Moreover, you didn't answer to my question. Why are you doing that
> call implicitly?
"implicitly" ? What's implicit here ? This is just pretty standard
cleanup after failure, you are being very cryptic here.
Please state precisely what it is you dislike with that code instead of
expecting us to guess and being nasty about it. Eddie was a genuine
question, he doesn't see what you think is "hurtful to the eyes" in the
code you quoted.
> > > > + if (!list_empty(&i2c->ports)) {
> > >
> > > My gosh, this is done already in list_for_each*()
> > No, list_for_each_entry does NOT check if the list is empty or if the first
> > entry is NULL.
>
> Please, read the macro source code again.
Cheers,
Ben.
On Thu, May 31, 2018 at 1:34 AM, Benjamin Herrenschmidt
<[email protected]> wrote:
> On Thu, 2018-05-31 at 00:27 +0300, Andy Shevchenko wrote:
>> On Wed, May 30, 2018 at 6:47 PM, Eddie James <[email protected]> wrote:
>> > On 05/29/2018 06:19 PM, Andy Shevchenko wrote:
>> > > On Wed, May 30, 2018 at 1:24 AM, Eddie James <[email protected]>
>> > > wrote:
>> > > Isn't below somehow repeats of_i2c_register_devices() ?
>> > > Why not to use it?
>> > Because I need to assign all these port structure fields. Also looks like
>> > of_i2c_register_devices creates new devices; I just want an adapter for each
>> > port.
>>
>> Hmm... Wolfram, what is your opinion on this design?
>
> Andy, I don't understand your issue.
>
> of_i2c_register_devices() is about discovering the i2c devices below a
> given bus. This is not what is happening here.
>
> This is a driver for a master that supports multiple busses, so it the
> above loop creates all the busses.
My issue here, that it feels like a lot of duplication with existing approaches.
Though, it might be a right thing to do at the end. So, let's just
assume maintainer will give their point of view.
>> > > > + devm_kfree(dev, port);
>> > >
>> > > This hurts my eyes. Why?!
>> > What would you suggest instead?
>>
>> You even didn't wait for answer, why to ask then?
>
> Please stop being so rude.
OK.
>> Moreover, you didn't answer to my question. Why are you doing that
>> call implicitly?
>
> "implicitly" ? What's implicit here ? This is just pretty standard
> cleanup after failure, you are being very cryptic here.
>
> Please state precisely what it is you dislike with that code instead of
> expecting us to guess and being nasty about it. Eddie was a genuine
> question, he doesn't see what you think is "hurtful to the eyes" in the
> code you quoted.
In 99% cases when someone calls devm_kfree() it means wrong choice of
devm_k*alloc() in the first place.
So, with explanation given why it's done in this way I would rather
suggest to switch to plain k*alloc() / kfree().
Or do we really care about few hundreds of bytes wasted?
--
With Best Regards,
Andy Shevchenko
On 05/30/2018 04:16 PM, Benjamin Herrenschmidt wrote:
> On Wed, 2018-05-30 at 10:47 -0500, Eddie James wrote:
>>>> + if (!list_empty(&i2c->ports)) {
>>> My gosh, this is done already in list_for_each*()
>> No, list_for_each_entry does NOT check if the list is empty or if the
>> first entry is NULL.
> NULL is never valid for a list. It does however check for an empty list
>
> It does it implicitely in the test part of the for () statement,
> checking if the next pointer points back to the head.
Thanks Ben. My mistake on this one; I misread the macro. I will remove
the check in v9... going to wait a little for any further comments now.
Thanks,
Eddie
>
> Cheers,
> Ben.
>
>