[PATCH linux dev-4.10 v2 0/6] drivers: i2c: FSI-attached I2C master algorithm

[PATCH linux dev-4.10 v2 0/6] drivers: i2c: FSI-attached I2C master algorithm

[Eddie James]

From: "Edward A. James" <eajames@us.ibm.com>

This patch series adds an I2C bus algorithm to drive the I2C master located on
POWER CPUs. The master is accessed over FSI bus from the service processor.

The driver creates one chardev entry for each port off an I2C master by
registering one I2C adapter for port. This implementation requires locking of
the master in the driver to prevent transfers running into each other. The
master registers are shared between ports.

This patchset also adds the latest in FSI dt bindings from Jeremy Kerr. This
describes the entire FSI tree structure (master -> slaves -> engines ->
engine data (such as i2c master ports)). These bindings are required for the
I2C driver in order to enumerate the ports off each I2C master.

Edward A. James (6):
  drivers: i2c: Add FSI-attached I2C master algorithm
  drivers: i2c: Add port structure to FSI algorithm
  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
  dts: aspeed: witherspoon: Add I2C master under FSI masters

 arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dts | 156 ++++++
 drivers/Makefile                                 |   2 +-
 drivers/i2c/busses/Kconfig                       |  11 +
 drivers/i2c/busses/Makefile                      |   1 +
 drivers/i2c/busses/i2c-fsi.c                     | 654 +++++++++++++++++++++++
 5 files changed, 823 insertions(+), 1 deletion(-)
 create mode 100644 drivers/i2c/busses/i2c-fsi.c

-- 
1.8.3.1

[PATCH linux dev-4.10 v2 1/6] drivers: i2c: Add FSI-attached I2C master algorithm

[Eddie James]

From: "Edward A. James" <eajames@us.ibm.com>

Initial startup code for the I2C algorithm to drive the I2C master
located on POWER CPUs over FSI bus.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 drivers/Makefile             |   2 +-
 drivers/i2c/busses/Kconfig   |  11 ++
 drivers/i2c/busses/Makefile  |   1 +
 drivers/i2c/busses/i2c-fsi.c | 245 +++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 258 insertions(+), 1 deletion(-)
 create mode 100644 drivers/i2c/busses/i2c-fsi.c

diff --git a/drivers/Makefile b/drivers/Makefile
index 67ce51d..278f109 100644
--- a/drivers/Makefile
+++ b/drivers/Makefile
@@ -105,6 +105,7 @@ obj-$(CONFIG_SERIO)		+= input/serio/
 obj-$(CONFIG_GAMEPORT)		+= input/gameport/
 obj-$(CONFIG_INPUT)		+= input/
 obj-$(CONFIG_RTC_LIB)		+= rtc/
+obj-$(CONFIG_FSI)		+= fsi/
 obj-y				+= i2c/ media/
 obj-$(CONFIG_PPS)		+= pps/
 obj-y				+= ptp/
@@ -173,4 +174,3 @@ obj-$(CONFIG_STM)		+= hwtracing/stm/
 obj-$(CONFIG_ANDROID)		+= android/
 obj-$(CONFIG_NVMEM)		+= nvmem/
 obj-$(CONFIG_FPGA)		+= fpga/
-obj-$(CONFIG_FSI)		+= fsi/
diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index 7e34901d..0c714e0 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1245,4 +1245,15 @@ config I2C_OPAL
 	  This driver can also be built as a module. If so, the module will be
 	  called as i2c-opal.
 
+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 5798b4e..547773b 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -124,5 +124,6 @@ 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..3c1087d
--- /dev/null
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -0,0 +1,245 @@
+/*
+ * Copyright 2017 IBM Corporation
+ *
+ * Eddie James <eajames@us.ibm.com>
+ *
+ * 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/fsi.h>
+#include <linux/i2c.h>
+#include <linux/jiffies.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/sched.h>
+#include <linux/semaphore.h>
+#include <linux/wait.h>
+
+#define FSI_ENGID_I2C_FSI	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;
+	u32 raw_data;
+
+	rc = fsi_device_read(fsi, reg, &raw_data, sizeof(raw_data));
+	if (rc)
+		return rc;
+
+	*data = be32_to_cpu(raw_data);
+
+	return 0;
+}
+
+static int fsi_i2c_write_reg(struct fsi_device *fsi, unsigned int reg,
+			     u32 *data)
+{
+	u32 raw_data = cpu_to_be32(*data);
+
+	return fsi_device_write(fsi, reg, &raw_data, sizeof(raw_data));
+}
+
+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 -ENOSYS;
+}
+
+static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
+{
+	return I2C_FUNC_I2C | I2C_FUNC_PROTOCOL_MANGLING | I2C_FUNC_10BIT_ADDR;
+}
+
+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, FSI_VERSION_ANY },
+	{ 0 }
+};
+
+static struct fsi_driver fsi_i2c_driver = {
+	.id_table = fsi_i2c_ids,
+	.drv = {
+		.name = "i2c_master_fsi",
+		.bus = &fsi_bus_type,
+		.probe = fsi_i2c_probe,
+	},
+};
+
+module_fsi_driver(fsi_i2c_driver);
+
+MODULE_AUTHOR("Eddie James <eajames@us.ibm.com>");
+MODULE_DESCRIPTION("FSI attached I2C master");
+MODULE_LICENSE("GPL");
-- 
1.8.3.1

[PATCH linux dev-4.10 v2 2/6] drivers: i2c: Add port structure to FSI algorithm

[Eddie James]

From: "Edward A. James" <eajames@us.ibm.com>

Add and initialize I2C adapters for each port on the FSI-attached I2C
master. Ports are defined in the devicetree.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 113 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 112 insertions(+), 1 deletion(-)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 3c1087d..cdebc99 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -30,6 +30,7 @@
 #define SETFIELD(m, v, val)	\
 	(((v) & ~(m)) | ((((typeof(v))(val)) << MASK_TO_LSH(m)) & (m)))
 
+#define I2C_MASTER_NR_OFFSET	100
 #define I2C_DEFAULT_CLK_DIV	6
 
 /* i2c registers */
@@ -131,9 +132,21 @@
 
 struct fsi_i2c_master {
 	struct fsi_device	*fsi;
+	int			idx;
 	u8			fifo_size;
+	struct list_head	ports;
+	struct ida		ida;
 };
 
+struct fsi_i2c_port {
+	struct list_head	list;
+	struct i2c_adapter	adapter;
+	struct fsi_i2c_master	*master;
+	u16			port;
+};
+
+static DEFINE_IDA(fsi_i2c_ida);
+
 static int fsi_i2c_read_reg(struct fsi_device *fsi, unsigned int reg,
 			    u32 *data)
 {
@@ -188,9 +201,44 @@ 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 -ENOSYS;
 }
 
@@ -207,13 +255,59 @@ static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
 static int fsi_i2c_probe(struct device *dev)
 {
 	struct fsi_i2c_master *i2c;
-	int rc;
+	struct fsi_i2c_port *port;
+	struct device_node *np;
+	int rc, idx;
+	u32 port_no;
 
 	i2c = devm_kzalloc(dev, sizeof(*i2c), GFP_KERNEL);
 	if (!i2c)
 		return -ENOMEM;
 
 	i2c->fsi = to_fsi_dev(dev);
+	i2c->idx = ida_simple_get(&fsi_i2c_ida, 1, INT_MAX, GFP_KERNEL);
+	ida_init(&i2c->ida);
+	INIT_LIST_HEAD(&i2c->ports);
+
+	if (dev->of_node) {
+		/* add adapter for each i2c port of the master */
+		for_each_child_of_node(dev->of_node, np) {
+			rc = of_property_read_u32(np, "port", &port_no);
+			if (rc || port_no > 0xFFFF)
+				continue;
+
+			/* make sure we don't overlap index with a buggy dts */
+			idx = ida_simple_get(&i2c->ida, port_no,
+					     port_no + 1, GFP_KERNEL);
+			if (idx < 0)
+				continue;
+
+			port = devm_kzalloc(dev, sizeof(*port), GFP_KERNEL);
+			if (!port)
+				return -ENOMEM;
+
+			port->master = i2c;
+			port->port = (u16)port_no;
+
+			port->adapter.owner = THIS_MODULE;
+			port->adapter.dev.parent = dev;
+			port->adapter.algo = &fsi_i2c_algorithm;
+			port->adapter.algo_data = port;
+			/* number ports uniquely */
+			port->adapter.nr = (i2c->idx * I2C_MASTER_NR_OFFSET) +
+				port_no;
+
+			snprintf(port->adapter.name,
+				 sizeof(port->adapter.name),
+				 "fsi_i2c-%u", port_no);
+
+			rc = i2c_add_numbered_adapter(&port->adapter);
+			if (rc < 0)
+				return rc;
+
+			list_add(&port->list, &i2c->ports);
+		}
+	}
 
 	rc = fsi_i2c_dev_init(i2c);
 	if (rc)
@@ -224,6 +318,22 @@ static int fsi_i2c_probe(struct device *dev)
 	return 0;
 }
 
+static int fsi_i2c_remove(struct device *dev)
+{
+	struct fsi_i2c_master *i2c = dev_get_drvdata(dev);
+	struct fsi_i2c_port *port;
+
+	list_for_each_entry(port, &i2c->ports, list) {
+		i2c_del_adapter(&port->adapter);
+	}
+
+	ida_destroy(&i2c->ida);
+
+	ida_simple_remove(&fsi_i2c_ida, i2c->idx);
+
+	return 0;
+}
+
 static const struct fsi_device_id fsi_i2c_ids[] = {
 	{ FSI_ENGID_I2C_FSI, FSI_VERSION_ANY },
 	{ 0 }
@@ -235,6 +345,7 @@ static int fsi_i2c_probe(struct device *dev)
 		.name = "i2c_master_fsi",
 		.bus = &fsi_bus_type,
 		.probe = fsi_i2c_probe,
+		.remove = fsi_i2c_remove,
 	},
 };
 
-- 
1.8.3.1

[PATCH linux dev-4.10 v2 3/6] drivers: i2c: Add transfer implementation for FSI algorithm

[Eddie James]

From: "Edward A. James" <eajames@us.ibm.com>

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 <eajames@us.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 193 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 191 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index cdebc99..f690b16 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -143,6 +143,7 @@ struct fsi_i2c_port {
 	struct i2c_adapter	adapter;
 	struct fsi_i2c_master	*master;
 	u16			port;
+	u16			xfrd;
 };
 
 static DEFINE_IDA(fsi_i2c_ida);
@@ -229,17 +230,205 @@ 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_handle_status(struct fsi_i2c_port *port,
+				 struct i2c_msg *msg, u32 status)
+{
+	int rc;
+	u8 fifo_count;
+	struct fsi_i2c_master *i2c = port->master;
+	u32 dummy = 0;
+
+	if (status & I2C_STAT_ERR) {
+		rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+		if (rc)
+			return rc;
+
+		if (status & I2C_STAT_NACK)
+			return -EFAULT;
+
+		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;
+}
+
+static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
+			unsigned long timeout)
+{
+	const unsigned long local_timeout = 2; /* jiffies */
+	u32 status = 0;
+	int rc;
+
+	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;
+		}
+
+		set_current_state(TASK_UNINTERRUPTIBLE);
+		schedule_timeout(local_timeout);
+		timeout = (timeout < local_timeout) ? 0 :
+			timeout - local_timeout;
+	} while (timeout);
+
+	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 -ENOSYS;
+	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

[PATCH linux dev-4.10 v2 4/6] drivers: i2c: Add I2C master locking to FSI algorithm

[Eddie James]

From: "Edward A. James" <eajames@us.ibm.com>

Since there are many ports per master, each with it's own adapter and
chardev, we need some locking to prevent xfers from changing the master
state while other xfers are in progress.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 41 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 37 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index f690b16..d757aee 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -136,6 +136,8 @@ struct fsi_i2c_master {
 	u8			fifo_size;
 	struct list_head	ports;
 	struct ida		ida;
+	wait_queue_head_t	wait;
+	struct semaphore	lock;
 };
 
 struct fsi_i2c_port {
@@ -171,6 +173,29 @@ static int fsi_i2c_write_reg(struct fsi_device *fsi, unsigned int reg,
 	return fsi_device_write(fsi, reg, &raw_data, sizeof(raw_data));
 }
 
+static int fsi_i2c_lock_master(struct fsi_i2c_master *i2c, int timeout)
+{
+	int rc;
+
+	rc = down_trylock(&i2c->lock);
+	if (!rc)
+		return 0;
+
+	rc = wait_event_interruptible_timeout(i2c->wait,
+					      !down_trylock(&i2c->lock),
+					      timeout);
+	if (rc > 0)
+		return 0;
+
+	return -EBUSY;
+}
+
+static void fsi_i2c_unlock_master(struct fsi_i2c_master *i2c)
+{
+	up(&i2c->lock);
+	wake_up(&i2c->wait);
+}
+
 static int fsi_i2c_dev_init(struct fsi_i2c_master *i2c)
 {
 	int rc;
@@ -410,25 +435,31 @@ static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 	struct fsi_i2c_port *port = adap->algo_data;
 	struct i2c_msg *msg;
 
-	rc = fsi_i2c_set_port(port);
+	rc = fsi_i2c_lock_master(port->master, adap->timeout);
 	if (rc)
 		return rc;
 
+	rc = fsi_i2c_set_port(port);
+	if (rc)
+		goto unlock;
+
 	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;
+			goto unlock;
 
 		rc = fsi_i2c_wait(port, msg,
 				  adap->timeout - (jiffies - start_time));
 		if (rc)
-			return rc;
+			goto unlock;
 	}
 
-	return 0;
+unlock:
+	fsi_i2c_unlock_master(port->master);
+	return rc;
 }
 
 static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
@@ -453,6 +484,8 @@ static int fsi_i2c_probe(struct device *dev)
 	if (!i2c)
 		return -ENOMEM;
 
+	init_waitqueue_head(&i2c->wait);
+	sema_init(&i2c->lock, 1);
 	i2c->fsi = to_fsi_dev(dev);
 	i2c->idx = ida_simple_get(&fsi_i2c_ida, 1, INT_MAX, GFP_KERNEL);
 	ida_init(&i2c->ida);
-- 
1.8.3.1

[PATCH linux dev-4.10 v2 5/6] drivers: i2c: Add bus recovery for FSI algorithm

[Eddie James]

From: "Edward A. James" <eajames@us.ibm.com>

Bus recovery should reset the engine and force block the bus 9 times
to recover most situations.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 76 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 76 insertions(+)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index d757aee..4689479 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -467,6 +467,80 @@ static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
 	return I2C_FUNC_I2C | I2C_FUNC_PROTOCOL_MANGLING | I2C_FUNC_10BIT_ADDR;
 }
 
+static int fsi_i2c_low_level_recover_bus(struct fsi_i2c_master *i2c)
+{
+	int i, rc;
+	u32 mode, 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);
+
+	return rc;
+}
+
+static int fsi_i2c_recover_bus(struct i2c_adapter *adap)
+{
+	int rc;
+	u32 dummy = 0;
+	struct fsi_i2c_port *port = adap->algo_data;
+	struct fsi_i2c_master *i2c = port->master;
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_dev_init(i2c);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_low_level_recover_bus(i2c);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+
+	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,
@@ -514,6 +588,8 @@ static int fsi_i2c_probe(struct device *dev)
 			port->adapter.owner = THIS_MODULE;
 			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;
 			/* number ports uniquely */
 			port->adapter.nr = (i2c->idx * I2C_MASTER_NR_OFFSET) +
-- 
1.8.3.1

[PATCH linux dev-4.10 v2 6/6] dts: aspeed: witherspoon: Add I2C master under FSI masters

[Eddie James]

From: "Edward A. James" <eajames@us.ibm.com>

Include all the ports that are present off I2C engine on P9.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dts | 156 +++++++++++++++++++++++
 1 file changed, 156 insertions(+)

diff --git a/arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dts b/arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dts
index f20aaf4..ac903c8 100644
--- a/arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dts
+++ b/arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dts
@@ -65,6 +65,8 @@
 
 	gpio-fsi {
 		compatible = "fsi-master-gpio", "fsi-master";
+		#address-cells = <2>;
+		#size-cells = <0>;
 
 		status = "okay";
 
@@ -73,6 +75,160 @@
 		mux-gpios = <&gpio ASPEED_GPIO(A, 6) GPIO_ACTIVE_HIGH>;
 		enable-gpios = <&gpio ASPEED_GPIO(D, 0) GPIO_ACTIVE_HIGH>;
 		trans-gpios = <&gpio ASPEED_GPIO(R, 2) GPIO_ACTIVE_HIGH>;
+
+		cfam@0,0 {
+			reg = <0 0>;
+			#address-cells = <1>;
+			#size-cells = <1>;
+
+			i2c-master@1800 {
+				compatible = "ibm,fsi-i2c-master";
+				reg = <0x1800 0x400>;
+				#address-cells = <1>;
+				#size-cells = <0>;
+
+				port@0 {
+					port = <0>;
+				};
+
+				port@1 {
+					port = <1>;
+				};
+
+				port@2 {
+					port = <2>;
+				};
+
+				port@3 {
+					port = <3>;
+				};
+
+				port@4 {
+					port = <4>;
+				};
+
+				port@5 {
+					port = <5>;
+				};
+
+				port@6 {
+					port = <6>;
+				};
+
+				port@7 {
+					port = <7>;
+				};
+
+				port@8 {
+					port = <8>;
+				};
+
+				port@9 {
+					port = <9>;
+				};
+
+				port@10 {
+					port = <10>;
+				};
+
+				port@11 {
+					port = <11>;
+				};
+
+				port@12 {
+					port = <12>;
+				};
+
+				port@13 {
+					port = <13>;
+				};
+
+				port@14 {
+					port = <14>;
+				};
+			};
+
+			hub@3400 {
+				compatible = "fsi-master-hub";
+				reg = <0x3400 0x400>;
+				#address-cells = <2>;
+				#size-cells = <0>;
+
+				cfam@1,0 {
+					reg = <1 0>;
+					#address-cells = <1>;
+					#size-cells = <1>;
+
+					i2c-master@1800 {
+						compatible = "ibm,fsi-i2c-master";
+						reg = <0x1800 0x400>;
+						#address-cells = <1>;
+						#size-cells = <0>;
+
+						port@0 {
+							port = <0>;
+						};
+
+						port@1 {
+							port = <1>;
+						};
+
+						port@2 {
+							port = <2>;
+						};
+
+						port@3 {
+							port = <3>;
+						};
+
+						port@4 {
+							port = <4>;
+						};
+
+						port@5 {
+							port = <5>;
+						};
+
+						port@6 {
+							port = <6>;
+						};
+
+						port@7 {
+							port = <7>;
+						};
+
+						port@8 {
+							port = <8>;
+						};
+
+						port@9 {
+							port = <9>;
+						};
+
+						port@10 {
+							port = <10>;
+						};
+
+						port@11 {
+							port = <11>;
+						};
+
+						port@12 {
+							port = <12>;
+						};
+
+						port@13 {
+							port = <13>;
+						};
+
+						port@14 {
+							port = <14>;
+						};
+					};
+
+				};
+			};
+		};
 	};
 
 	iio-hwmon {
-- 
1.8.3.1

Re: [PATCH linux dev-4.10 v2 0/6] drivers: i2c: FSI-attached I2C master algorithm

[Joel Stanley]

On Thu, May 11, 2017 at 1:22 AM, Eddie James <eajames@linux.vnet.ibm.com> wrote:
> From: "Edward A. James" <eajames@us.ibm.com>
>
> This patch series adds an I2C bus algorithm to drive the I2C master located on
> POWER CPUs. The master is accessed over FSI bus from the service processor.
>
> The driver creates one chardev entry for each port off an I2C master by
> registering one I2C adapter for port. This implementation requires locking of
> the master in the driver to prevent transfers running into each other. The
> master registers are shared between ports.
>
> This patchset also adds the latest in FSI dt bindings from Jeremy Kerr. This
> describes the entire FSI tree structure (master -> slaves -> engines ->
> engine data (such as i2c master ports)). These bindings are required for the
> I2C driver in order to enumerate the ports off each I2C master.
>

I have added this series to dev-4.10. Note that under our kernel
rules, this means you must be in the process of submitting them
upstream :)

I think you can send them to the i2c maintainer with a mention in your
cover letter that it depends on the unmerged FSI series and that you'd
like to kick off the review process for your driver.

Cheers,

Joel


> Edward A. James (6):
>   drivers: i2c: Add FSI-attached I2C master algorithm
>   drivers: i2c: Add port structure to FSI algorithm
>   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
>   dts: aspeed: witherspoon: Add I2C master under FSI masters
>
>  arch/arm/boot/dts/aspeed-bmc-opp-witherspoon.dts | 156 ++++++
>  drivers/Makefile                                 |   2 +-
>  drivers/i2c/busses/Kconfig                       |  11 +
>  drivers/i2c/busses/Makefile                      |   1 +
>  drivers/i2c/busses/i2c-fsi.c                     | 654 +++++++++++++++++++++++
>  5 files changed, 823 insertions(+), 1 deletion(-)
>  create mode 100644 drivers/i2c/busses/i2c-fsi.c
>
> --
> 1.8.3.1
>

Re: [PATCH linux dev-4.10 v2 3/6] drivers: i2c: Add transfer implementation for FSI algorithm

[Joel Stanley]

On Thu, May 11, 2017 at 1:22 AM, Eddie James <eajames@linux.vnet.ibm.com> wrote:
> From: "Edward A. James" <eajames@us.ibm.com>
>
> 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 <eajames@us.ibm.com>
> ---
>  drivers/i2c/busses/i2c-fsi.c | 193 ++++++++++++++++++++++++++++++++++++++++++-
>  1 file changed, 191 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
> index cdebc99..f690b16 100644
> --- a/drivers/i2c/busses/i2c-fsi.c
> +++ b/drivers/i2c/busses/i2c-fsi.c
> @@ -143,6 +143,7 @@ struct fsi_i2c_port {
>         struct i2c_adapter      adapter;
>         struct fsi_i2c_master   *master;
>         u16                     port;
> +       u16                     xfrd;
>  };
>
>  static DEFINE_IDA(fsi_i2c_ida);
> @@ -229,17 +230,205 @@ 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_handle_status(struct fsi_i2c_port *port,
> +                                struct i2c_msg *msg, u32 status)
> +{
> +       int rc;
> +       u8 fifo_count;
> +       struct fsi_i2c_master *i2c = port->master;
> +       u32 dummy = 0;
> +
> +       if (status & I2C_STAT_ERR) {
> +               rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
> +               if (rc)
> +                       return rc;
> +
> +               if (status & I2C_STAT_NACK)
> +                       return -EFAULT;

Why EFAULT?

> +
> +               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;

rc is returned uninitialised here when all of the if () tests are false.


> +}
> +
> +static int fsi_i2c_wait(struct fsi_i2c_port *port, struct i2c_msg *msg,
> +                       unsigned long timeout)
> +{
> +       const unsigned long local_timeout = 2; /* jiffies */
> +       u32 status = 0;
> +       int rc;
> +
> +       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;
> +               }
> +
> +               set_current_state(TASK_UNINTERRUPTIBLE);
> +               schedule_timeout(local_timeout);

This is an open coded msleep(2). Just use msleep.

> +               timeout = (timeout < local_timeout) ? 0 :
> +                       timeout - local_timeout;

And then this could be (untested):

end = timeout + jiffies;

do {

} while (time_is_before_jiffies(end));


> +       } while (timeout);
> +
> +       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 -ENOSYS;
> +       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
>