[PATCH v6 0/7] drivers/i2c: Add FSI-attached I2C master algorithm

[PATCH v6 0/7] drivers/i2c: Add FSI-attached I2C master algorithm

[Eddie James]

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

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 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                      | 793 ++++++++++++++++++++++
 4 files changed, 845 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/i2c/i2c-fsi.txt
 create mode 100644 drivers/i2c/busses/i2c-fsi.c

-- 
1.8.3.1

[PATCH v6 1/7] dt-bindings: i2c: Add FSI-attached I2C master dt binding documentation

[Eddie James]

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

Document the bindings.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
Acked-by: Rob Herring <robh@kernel.org>
---
 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

[PATCH v6 2/7] drivers/i2c: Add FSI-attached I2C master algorithm

[Eddie James]

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

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 <eajames@us.ibm.com>
---
 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 009345d..4db3f44 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1331,4 +1331,15 @@ 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 2ce8576..f0ddead 100644
--- a/drivers/i2c/busses/Makefile
+++ b/drivers/i2c/busses/Makefile
@@ -136,5 +136,6 @@ 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 <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/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 <eajames@us.ibm.com>");
+MODULE_DESCRIPTION("FSI attached I2C master");
+MODULE_LICENSE("GPL");
-- 
1.8.3.1

[PATCH v6 3/7] 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 for each master are defined in the devicetree.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 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

[PATCH v6 4/7] drivers/i2c: Add abort and hardware reset procedures

[Eddie James]

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

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 <eajames@us.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 186 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 186 insertions(+)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 4ad5d68..61609bce 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -9,14 +9,18 @@
  * 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>
 #include <linux/of.h>
+#include <linux/sched.h>
+#include <linux/spinlock.h>
 
 #define FSI_ENGID_I2C		0x7
 
@@ -129,10 +133,18 @@
 #define I2C_ESTAT_SELF_BUSY	0x00000040
 #define I2C_ESTAT_VERSION	0x0000001f
 
+#define I2C_PORT_BUSY_RESET	0x80000000
+
+#define I2C_LOCAL_WAIT_TIMEOUT	2		/* jiffies */
+
+/* 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;
 	struct list_head	ports;
+	spinlock_t		reset_lock;
 };
 
 struct fsi_i2c_port {
@@ -224,6 +236,179 @@ 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;
+	unsigned long flags;
+
+	/* disable pre-emption; bus won't get left in a bad state for long */
+	spin_lock_irqsave(&i2c->reset_lock, flags);
+
+	/* reset engine */
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+	if (rc)
+		goto done;
+
+	/* re-init engine */
+	rc = fsi_i2c_dev_init(i2c);
+	if (rc)
+		goto done;
+
+	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+	if (rc)
+		goto done;
+
+	/* 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)
+			goto done;
+	}
+
+	/* reset busy register; hw workaround */
+	dummy = I2C_PORT_BUSY_RESET;
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_PORT_BUSY, &dummy);
+	if (rc)
+		goto done;
+
+	/* force bus reset */
+	rc = fsi_i2c_reset_bus(i2c);
+	if (rc)
+		goto done;
+
+	/* reset errors */
+	dummy = 0;
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+	if (rc)
+		goto done;
+
+	/* wait for command complete; time from legacy driver */
+	udelay(1000);
+
+	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
+	if (rc)
+		goto done;
+
+	if (stat & I2C_STAT_CMD_COMP)
+		goto done;
+
+	/* failed to get command complete; reset engine again */
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_I2C, &dummy);
+	if (rc)
+		goto done;
+
+	/* re-init engine again */
+	rc = fsi_i2c_dev_init(i2c);
+
+done:
+	spin_unlock_irqrestore(&i2c->reset_lock, flags);
+	return rc;
+}
+
+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;
+
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (schedule_timeout(I2C_LOCAL_WAIT_TIMEOUT) > 0)
+			return -EINTR;
+
+	} 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)
 {
@@ -260,6 +445,7 @@ static int fsi_i2c_probe(struct device *dev)
 	if (!i2c)
 		return -ENOMEM;
 
+	spin_lock_init(&i2c->reset_lock);
 	i2c->fsi = to_fsi_dev(dev);
 	INIT_LIST_HEAD(&i2c->ports);
 
-- 
1.8.3.1

[PATCH v6 5/7] 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 | 214 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 212 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 61609bce..5c312ef 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -152,6 +152,7 @@ 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,
@@ -236,6 +237,103 @@ 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;
@@ -409,17 +507,129 @@ 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, rc_abort;
+	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;
+		}
+
+		set_current_state(TASK_INTERRUPTIBLE);
+		if (schedule_timeout(I2C_LOCAL_WAIT_TIMEOUT) > 0) {
+			rc = -EINTR;
+			goto abort;
+		}
+	} while (time_after(start + timeout, jiffies));
+
+	rc = -ETIME;
+
+abort:
+	rc_abort = fsi_i2c_abort(port, status);
+	if (rc_abort)
+		return rc_abort;
+
+	return rc;
+}
+
 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

[PATCH v6 6/7] 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 transfers from changing the
master state while other transfers are in progress.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 43 +++++++++++++++++++++++++++++++++++++++----
 1 file changed, 39 insertions(+), 4 deletions(-)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 5c312ef..1751c44 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -20,7 +20,9 @@
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/sched.h>
+#include <linux/semaphore.h>
 #include <linux/spinlock.h>
+#include <linux/wait.h>
 
 #define FSI_ENGID_I2C		0x7
 
@@ -144,6 +146,8 @@ struct fsi_i2c_master {
 	struct fsi_device	*fsi;
 	u8			fifo_size;
 	struct list_head	ports;
+	wait_queue_head_t	wait;
+	struct semaphore	lock;
 	spinlock_t		reset_lock;
 };
 
@@ -178,6 +182,29 @@ static int fsi_i2c_write_reg(struct fsi_device *fsi, unsigned int reg,
 	return fsi_device_write(fsi, reg, &data_be, sizeof(data_be));
 }
 
+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;
@@ -611,25 +638,31 @@ 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)
@@ -655,6 +688,8 @@ static int fsi_i2c_probe(struct device *dev)
 	if (!i2c)
 		return -ENOMEM;
 
+	init_waitqueue_head(&i2c->wait);
+	sema_init(&i2c->lock, 1);
 	spin_lock_init(&i2c->reset_lock);
 	i2c->fsi = to_fsi_dev(dev);
 	INIT_LIST_HEAD(&i2c->ports);
-- 
1.8.3.1

[PATCH v6 7/7] 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 clock the bus 9 times
to recover most situations.

Signed-off-by: Edward A. James <eajames@us.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 22 ++++++++++++++++++++++
 1 file changed, 22 insertions(+)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 1751c44..10f693f 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -671,6 +671,27 @@ 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;
+
+	rc = fsi_i2c_lock_master(master, adap->timeout);
+	if (rc)
+		return rc;
+
+	rc = fsi_i2c_reset(master, port->port);
+
+	fsi_i2c_unlock_master(master);
+
+	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,
@@ -715,6 +736,7 @@ 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