[PATCH v11 0/8] i2c: Add FSI-attached I2C master algorithm

[PATCH v11 0/8] i2c: Add FSI-attached I2C master algorithm

[Eddie James]

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 v10
 - Add myself to maintainers
 - Rework the reset path. Use generic bus recovery and only do the reset if SDA
   is low.
 - Fixed email signature on dts patch
 - Pulled in Ben H's fix for use-after-free in remove()

Changes since v9
 - Switch the status masks to use a combination of bits rather than directly
   coding the value
 - Remove the interrupt mask definition as it was unused
 - Fixed return value of master_xfer function (return number of xfrs, not 0)

Changes since v8
 - Drop unecessary else statements
 - Use i++ instead of ++i
 - Use kzalloc/kfree instead of devm_kzalloc/devm_kfree for port structure
 - Drop the list_empty check in remove

Changes since v7
 - Fix grammer in Kconfig (a -> an)
 - Change I2C registers to use BIT and GENMASK
 - Remove custom macros and use FIELD_PREP and FIELD_GET
 - Fix a few unecessary initializations and "return rc" that are always zero
 - Clean up the read/write fifo functions a bit
 - Few other clean-up items

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

Eddie James (8):
  dt-bindings: i2c: Add FSI-attached I2C master dt binding documentation
  i2c: Add FSI-attached I2C master algorithm
  i2c: fsi: Add port structures
  i2c: fsi: Add abort and hardware reset procedures
  i2c: fsi: Add transfer implementation
  i2c: fsi: Add I2C master locking
  i2c: fsi: Add bus recovery
  MAINTAINERS: Add Eddie as the maintainer for the FSI-attached I2C
    driver

 Documentation/devicetree/bindings/i2c/i2c-fsi.txt |  40 ++
 MAINTAINERS                                       |   8 +
 drivers/i2c/busses/Kconfig                        |  11 +
 drivers/i2c/busses/Makefile                       |   1 +
 drivers/i2c/busses/i2c-fsi.c                      | 753 ++++++++++++++++++++++
 5 files changed, 813 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 v11 1/8] dt-bindings: i2c: Add FSI-attached I2C master dt binding documentation

[Eddie James]

Document the bindings.

Signed-off-by: Eddie James <eajames@linux.vnet.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 v11 2/8] i2c: Add FSI-attached I2C master algorithm

[Eddie James]

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: Eddie James <eajames@linux.vnet.ibm.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 drivers/i2c/busses/Kconfig   |  11 ++
 drivers/i2c/busses/Makefile  |   1 +
 drivers/i2c/busses/i2c-fsi.c | 240 +++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 252 insertions(+)
 create mode 100644 drivers/i2c/busses/i2c-fsi.c

diff --git a/drivers/i2c/busses/Kconfig b/drivers/i2c/busses/Kconfig
index e7a4d28..48b5de7 100644
--- a/drivers/i2c/busses/Kconfig
+++ b/drivers/i2c/busses/Kconfig
@@ -1327,4 +1327,15 @@ 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 an 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..694bbb4
--- /dev/null
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -0,0 +1,240 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * FSI-attached I2C master algorithm
+ *
+ * Copyright 2018 IBM Corporation
+ *
+ * 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/bitfield.h>
+#include <linux/bitops.h>
+#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
+
+#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	BIT(31)
+#define I2C_CMD_WITH_ADDR	BIT(30)
+#define I2C_CMD_RD_CONT		BIT(29)
+#define I2C_CMD_WITH_STOP	BIT(28)
+#define I2C_CMD_FORCELAUNCH	BIT(27)
+#define I2C_CMD_ADDR		GENMASK(23, 17)
+#define I2C_CMD_READ		BIT(16)
+#define I2C_CMD_LEN		GENMASK(15, 0)
+
+/* mode register */
+#define I2C_MODE_CLKDIV		GENMASK(31, 16)
+#define I2C_MODE_PORT		GENMASK(15, 10)
+#define I2C_MODE_ENHANCED	BIT(3)
+#define I2C_MODE_DIAG		BIT(2)
+#define I2C_MODE_PACE_ALLOW	BIT(1)
+#define I2C_MODE_WRAP		BIT(0)
+
+/* watermark register */
+#define I2C_WATERMARK_HI	GENMASK(15, 12)
+#define I2C_WATERMARK_LO	GENMASK(7, 4)
+
+#define I2C_FIFO_HI_LVL		4
+#define I2C_FIFO_LO_LVL		4
+
+/* interrupt register */
+#define I2C_INT_INV_CMD		BIT(15)
+#define I2C_INT_PARITY		BIT(14)
+#define I2C_INT_BE_OVERRUN	BIT(13)
+#define I2C_INT_BE_ACCESS	BIT(12)
+#define I2C_INT_LOST_ARB	BIT(11)
+#define I2C_INT_NACK		BIT(10)
+#define I2C_INT_DAT_REQ		BIT(9)
+#define I2C_INT_CMD_COMP	BIT(8)
+#define I2C_INT_STOP_ERR	BIT(7)
+#define I2C_INT_BUSY		BIT(6)
+#define I2C_INT_IDLE		BIT(5)
+
+/* status register */
+#define I2C_STAT_INV_CMD	BIT(31)
+#define I2C_STAT_PARITY		BIT(30)
+#define I2C_STAT_BE_OVERRUN	BIT(29)
+#define I2C_STAT_BE_ACCESS	BIT(28)
+#define I2C_STAT_LOST_ARB	BIT(27)
+#define I2C_STAT_NACK		BIT(26)
+#define I2C_STAT_DAT_REQ	BIT(25)
+#define I2C_STAT_CMD_COMP	BIT(24)
+#define I2C_STAT_STOP_ERR	BIT(23)
+#define I2C_STAT_MAX_PORT	GENMASK(19, 16)
+#define I2C_STAT_ANY_INT	BIT(15)
+#define I2C_STAT_SCL_IN		BIT(11)
+#define I2C_STAT_SDA_IN		BIT(10)
+#define I2C_STAT_PORT_BUSY	BIT(9)
+#define I2C_STAT_SELF_BUSY	BIT(8)
+#define I2C_STAT_FIFO_COUNT	GENMASK(7, 0)
+
+#define I2C_STAT_ERR		(I2C_STAT_INV_CMD |			\
+				 I2C_STAT_PARITY |			\
+				 I2C_STAT_BE_OVERRUN |			\
+				 I2C_STAT_BE_ACCESS |			\
+				 I2C_STAT_LOST_ARB |			\
+				 I2C_STAT_NACK |			\
+				 I2C_STAT_STOP_ERR)
+#define I2C_STAT_ANY_RESP	(I2C_STAT_ERR |				\
+				 I2C_STAT_DAT_REQ |			\
+				 I2C_STAT_CMD_COMP)
+
+/* extended status register */
+#define I2C_ESTAT_FIFO_SZ	GENMASK(31, 24)
+#define I2C_ESTAT_SCL_IN_SY	BIT(15)
+#define I2C_ESTAT_SDA_IN_SY	BIT(14)
+#define I2C_ESTAT_S_SCL		BIT(13)
+#define I2C_ESTAT_S_SDA		BIT(12)
+#define I2C_ESTAT_M_SCL		BIT(11)
+#define I2C_ESTAT_M_SDA		BIT(10)
+#define I2C_ESTAT_HI_WATER	BIT(9)
+#define I2C_ESTAT_LO_WATER	BIT(8)
+#define I2C_ESTAT_PORT_BUSY	BIT(7)
+#define I2C_ESTAT_SELF_BUSY	BIT(6)
+#define I2C_ESTAT_VERSION	GENMASK(4, 0)
+
+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_be32p(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;
+	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 |= FIELD_PREP(I2C_MODE_CLKDIV, 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 = FIELD_GET(I2C_ESTAT_FIFO_SZ, extended_status);
+	watermark = FIELD_PREP(I2C_WATERMARK_HI,
+			       i2c->fifo_size - I2C_FIFO_HI_LVL);
+	watermark |= FIELD_PREP(I2C_WATERMARK_LO, I2C_FIFO_LO_LVL);
+
+	return fsi_i2c_write_reg(i2c->fsi, I2C_FSI_WATER_MARK, &watermark);
+}
+
+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 },
+	{ }
+};
+
+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 v11 3/8] i2c: fsi: Add port structures

[Eddie James]

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: Eddie James <eajames@linux.vnet.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 91 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 694bbb4..89b7349 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -17,7 +17,10 @@
 #include <linux/fsi.h>
 #include <linux/i2c.h>
 #include <linux/kernel.h>
+#include <linux/list.h>
 #include <linux/module.h>
+#include <linux/of.h>
+#include <linux/slab.h>
 
 #define FSI_ENGID_I2C		0x7
 
@@ -128,6 +131,14 @@
 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,
@@ -181,9 +192,38 @@ static int fsi_i2c_dev_init(struct fsi_i2c_master *i2c)
 	return fsi_i2c_write_reg(i2c->fsi, I2C_FSI_WATER_MARK, &watermark);
 }
 
+static int fsi_i2c_set_port(struct fsi_i2c_port *port)
+{
+	int rc;
+	struct fsi_device *fsi = port->master->fsi;
+	u32 mode, dummy = 0;
+
+	rc = fsi_i2c_read_reg(fsi, I2C_FSI_MODE, &mode);
+	if (rc)
+		return rc;
+
+	if (FIELD_GET(I2C_MODE_PORT, mode) == port->port)
+		return 0;
+
+	mode = (mode & ~I2C_MODE_PORT) | FIELD_PREP(I2C_MODE_PORT, port->port);
+	rc = fsi_i2c_write_reg(fsi, I2C_FSI_MODE, &mode);
+	if (rc)
+		return rc;
+
+	/* reset engine when port is changed */
+	return fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
+}
+
 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;
 }
 
@@ -202,23 +242,73 @@ 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 = kzalloc(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);
+			kfree(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, *tmp;
+
+	list_for_each_entry_safe(port, tmp, &i2c->ports, list) {
+		list_del(&port->list);
+		i2c_del_adapter(&port->adapter);
+		kfree(port);
+	}
+
+	return 0;
+}
+
 static const struct fsi_device_id fsi_i2c_ids[] = {
 	{ FSI_ENGID_I2C, FSI_VERSION_ANY },
 	{ }
@@ -230,6 +320,7 @@ 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 v11 4/8] i2c: fsi: Add abort and hardware reset procedures

[Eddie James]

Add abort procedure for failed transfers. Add engine reset procedure
that is executed during the abort to recover from various fault
conditions.

Signed-off-by: Eddie James <eajames@linux.vnet.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 91 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 89b7349..8f1e611 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -12,10 +12,12 @@
 
 #include <linux/bitfield.h>
 #include <linux/bitops.h>
+#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>
@@ -128,6 +130,20 @@
 #define I2C_ESTAT_SELF_BUSY	BIT(6)
 #define I2C_ESTAT_VERSION	GENMASK(4, 0)
 
+/* port busy register */
+#define I2C_PORT_BUSY_RESET	BIT(31)
+
+/* wait for command complete or data request */
+#define I2C_CMD_SLEEP_MAX_US	500
+#define I2C_CMD_SLEEP_MIN_US	50
+
+/* wait after reset; choose time from legacy driver */
+#define I2C_RESET_SLEEP_MAX_US	2000
+#define I2C_RESET_SLEEP_MIN_US	1000
+
+/* 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;
@@ -214,6 +230,81 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
 	return fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
 }
 
+static int fsi_i2c_reset_engine(struct fsi_i2c_master *i2c, u16 port)
+{
+	int rc;
+	u32 mode, 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 &= ~I2C_MODE_PORT;
+		mode |= FIELD_PREP(I2C_MODE_PORT, 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;
+
+	return 0;
+}
+
+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_i2c_master *i2c = port->master;
+	struct fsi_device *fsi = i2c->fsi;
+
+	rc = fsi_i2c_reset_engine(i2c, 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_CMD_SLEEP_MIN_US, I2C_CMD_SLEEP_MAX_US);
+	} while (time_after(start + I2C_ABORT_TIMEOUT, jiffies));
+
+	return -ETIMEDOUT;
+}
+
 static int fsi_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,
 			int num)
 {
-- 
1.8.3.1

[PATCH v11 5/8] i2c: fsi: Add transfer implementation

[Eddie James]

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: Eddie James <eajames@linux.vnet.ibm.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 drivers/i2c/busses/i2c-fsi.c | 195 ++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 193 insertions(+), 2 deletions(-)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 8f1e611..6cb4602 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -155,6 +155,7 @@ 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,
@@ -230,6 +231,99 @@ static int fsi_i2c_set_port(struct fsi_i2c_port *port)
 	return fsi_i2c_write_reg(fsi, I2C_FSI_RESET_ERR, &dummy);
 }
 
+static int fsi_i2c_start(struct fsi_i2c_port *port, struct i2c_msg *msg,
+			 bool stop)
+{
+	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 |= FIELD_PREP(I2C_CMD_ADDR, msg->addr >> 1);
+	cmd |= FIELD_PREP(I2C_CMD_LEN, msg->len);
+
+	return fsi_i2c_write_reg(i2c->fsi, I2C_FSI_CMD, &cmd);
+}
+
+static int fsi_i2c_get_op_bytes(int op_bytes)
+{
+	/* fsi is limited to max 4 byte aligned ops */
+	if (op_bytes > 4)
+		return 4;
+	else if (op_bytes == 3)
+		return 2;
+	return op_bytes;
+}
+
+static int fsi_i2c_write_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
+			      u8 fifo_count)
+{
+	int write;
+	int rc;
+	struct fsi_i2c_master *i2c = port->master;
+	int bytes_to_write = i2c->fifo_size - fifo_count;
+	int bytes_remaining = msg->len - port->xfrd;
+
+	bytes_to_write = min(bytes_to_write, bytes_remaining);
+
+	while (bytes_to_write) {
+		write = fsi_i2c_get_op_bytes(bytes_to_write);
+
+		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 0;
+}
+
+static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
+			     u8 fifo_count)
+{
+	int read;
+	int rc;
+	struct fsi_i2c_master *i2c = port->master;
+	int bytes_to_read;
+	int xfr_remaining = msg->len - port->xfrd;
+	u32 dummy;
+
+	bytes_to_read = min_t(int, fifo_count, xfr_remaining);
+
+	while (bytes_to_read) {
+		read = fsi_i2c_get_op_bytes(bytes_to_read);
+
+		if (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;
+		}
+
+		bytes_to_read -= read;
+	}
+
+	return 0;
+}
+
 static int fsi_i2c_reset_engine(struct fsi_i2c_master *i2c, u16 port)
 {
 	int rc;
@@ -305,17 +399,114 @@ static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)
 	return -ETIMEDOUT;
 }
 
+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 = FIELD_GET(I2C_STAT_FIFO_COUNT, status);
+
+		if (msg->flags & I2C_M_RD)
+			return fsi_i2c_read_fifo(port, msg, fifo_count);
+
+		return fsi_i2c_write_fifo(port, msg, fifo_count);
+	}
+
+	if (status & I2C_STAT_CMD_COMP) {
+		if (port->xfrd < msg->len)
+			return -ENODATA;
+
+		return msg->len;
+	}
+
+	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_CMD_SLEEP_MIN_US, I2C_CMD_SLEEP_MAX_US);
+	} while (time_after(start + timeout, jiffies));
+
+	return -ETIMEDOUT;
+}
+
 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 num;
 }
 
 static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
-- 
1.8.3.1

[PATCH v11 6/8] i2c: fsi: Add I2C master locking

[Eddie James]

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: Eddie James <eajames@linux.vnet.ibm.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
---
 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 6cb4602..5520251 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -21,6 +21,7 @@
 #include <linux/kernel.h>
 #include <linux/list.h>
 #include <linux/module.h>
+#include <linux/mutex.h>
 #include <linux/of.h>
 #include <linux/slab.h>
 
@@ -148,6 +149,7 @@ struct fsi_i2c_master {
 	struct fsi_device	*fsi;
 	u8			fifo_size;
 	struct list_head	ports;
+	struct mutex		lock;
 };
 
 struct fsi_i2c_port {
@@ -486,11 +488,14 @@ 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;
@@ -498,15 +503,17 @@ 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 num;
+unlock:
+	mutex_unlock(&master->lock);
+	return rc ? : num;
 }
 
 static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
@@ -533,6 +540,7 @@ 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

[PATCH v11 7/8] i2c: fsi: Add bus recovery

[Eddie James]

Bus recovery should reset the bus with the standard i2c recovery
procedure. Populate the necessary fields so that the standard procedure
can perform the reset.

Signed-off-by: Eddie James <eajames@linux.vnet.ibm.com>
---
 drivers/i2c/busses/i2c-fsi.c | 132 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 132 insertions(+)

diff --git a/drivers/i2c/busses/i2c-fsi.c b/drivers/i2c/busses/i2c-fsi.c
index 5520251..42c387d 100644
--- a/drivers/i2c/busses/i2c-fsi.c
+++ b/drivers/i2c/busses/i2c-fsi.c
@@ -326,6 +326,115 @@ static int fsi_i2c_read_fifo(struct fsi_i2c_port *port, struct i2c_msg *msg,
 	return 0;
 }
 
+static int fsi_i2c_get_scl(struct i2c_adapter *adap)
+{
+	u32 stat = 0;
+	struct fsi_i2c_port *port = adap->algo_data;
+	struct fsi_i2c_master *i2c = port->master;
+
+	fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
+
+	return !!(stat & I2C_STAT_SCL_IN);
+}
+
+static void fsi_i2c_set_scl(struct i2c_adapter *adap, int val)
+{
+	u32 dummy = 0;
+	struct fsi_i2c_port *port = adap->algo_data;
+	struct fsi_i2c_master *i2c = port->master;
+
+	if (val)
+		fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SCL, &dummy);
+	else
+		fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SCL, &dummy);
+}
+
+static int fsi_i2c_get_sda(struct i2c_adapter *adap)
+{
+	u32 stat = 0;
+	struct fsi_i2c_port *port = adap->algo_data;
+	struct fsi_i2c_master *i2c = port->master;
+
+	fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
+
+	return !!(stat & I2C_STAT_SDA_IN);
+}
+
+static void fsi_i2c_set_sda(struct i2c_adapter *adap, int val)
+{
+	u32 dummy = 0;
+	struct fsi_i2c_port *port = adap->algo_data;
+	struct fsi_i2c_master *i2c = port->master;
+
+	if (val)
+		fsi_i2c_write_reg(i2c->fsi, I2C_FSI_SET_SDA, &dummy);
+	else
+		fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_SDA, &dummy);
+}
+
+static void fsi_i2c_prepare_recovery(struct i2c_adapter *adap)
+{
+	int rc;
+	u32 mode;
+	struct fsi_i2c_port *port = adap->algo_data;
+	struct fsi_i2c_master *i2c = port->master;
+
+	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+	if (rc)
+		return;
+
+	mode |= I2C_MODE_DIAG;
+	fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+}
+
+static void fsi_i2c_unprepare_recovery(struct i2c_adapter *adap)
+{
+	int rc;
+	u32 mode;
+	struct fsi_i2c_port *port = adap->algo_data;
+	struct fsi_i2c_master *i2c = port->master;
+
+	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+	if (rc)
+		return;
+
+	mode &= ~I2C_MODE_DIAG;
+	fsi_i2c_write_reg(i2c->fsi, I2C_FSI_MODE, &mode);
+}
+
+static int fsi_i2c_reset_bus(struct fsi_i2c_master *i2c,
+			     struct fsi_i2c_port *port)
+{
+	int rc;
+	u32 stat, dummy = 0;
+
+	/* force bus reset, ignore errors */
+	i2c_recover_bus(&port->adapter);
+
+	/* reset errors */
+	rc = fsi_i2c_write_reg(i2c->fsi, I2C_FSI_RESET_ERR, &dummy);
+	if (rc)
+		return rc;
+
+	/* wait for command complete */
+	usleep_range(I2C_RESET_SLEEP_MIN_US, I2C_RESET_SLEEP_MAX_US);
+
+	rc = fsi_i2c_read_reg(i2c->fsi, I2C_FSI_STAT, &stat);
+	if (rc)
+		return rc;
+
+	if (stat & I2C_STAT_CMD_COMP)
+		return 0;
+
+	/* 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_reset_engine(struct fsi_i2c_master *i2c, u16 port)
 {
 	int rc;
@@ -368,6 +477,7 @@ static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)
 	int rc;
 	unsigned long start;
 	u32 cmd = I2C_CMD_WITH_STOP;
+	u32 stat;
 	struct fsi_i2c_master *i2c = port->master;
 	struct fsi_device *fsi = i2c->fsi;
 
@@ -375,6 +485,17 @@ static int fsi_i2c_abort(struct fsi_i2c_port *port, u32 status)
 	if (rc)
 		return rc;
 
+	rc = fsi_i2c_read_reg(fsi, I2C_FSI_STAT, &stat);
+	if (rc)
+		return rc;
+
+	/* if sda is low, peform full bus reset */
+	if (!(stat & I2C_STAT_SDA_IN)) {
+		rc = fsi_i2c_reset_bus(i2c, 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;
@@ -523,6 +644,16 @@ static u32 fsi_i2c_functionality(struct i2c_adapter *adap)
 		I2C_FUNC_SMBUS_BLOCK_DATA;
 }
 
+static struct i2c_bus_recovery_info fsi_i2c_bus_recovery_info = {
+	.recover_bus = i2c_generic_scl_recovery,
+	.get_scl = fsi_i2c_get_scl,
+	.set_scl = fsi_i2c_set_scl,
+	.get_sda = fsi_i2c_get_sda,
+	.set_sda = fsi_i2c_set_sda,
+	.prepare_recovery = fsi_i2c_prepare_recovery,
+	.unprepare_recovery = fsi_i2c_unprepare_recovery,
+};
+
 static const struct i2c_algorithm fsi_i2c_algorithm = {
 	.master_xfer = fsi_i2c_xfer,
 	.functionality = fsi_i2c_functionality,
@@ -565,6 +696,7 @@ 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

[PATCH v11 8/8] MAINTAINERS: Add Eddie as the maintainer for the FSI-attached I2C driver

[Eddie James]

Signed-off-by: Eddie James <eajames@linux.vnet.ibm.com>
---
 MAINTAINERS | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/MAINTAINERS b/MAINTAINERS
index 10fd4c0..63f6d41 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -5888,6 +5888,14 @@ F:	fs/crypto/
 F:	include/linux/fscrypt*.h
 F:	Documentation/filesystems/fscrypt.rst
 
+FSI-ATTACHED I2C DRIVER
+M:	Eddie James <eajames@linux.vnet.ibm.com>
+L:	linux-i2c@vger.kernel.org
+L:	openbmc@lists.ozlabs.org (moderated for non-subscribers)
+S:	Maintained
+F:	drivers/i2c/busses/i2c-fsi.c
+F:	Documentation/devicetree/bindings/i2c/i2c-fsi.txt
+
 FSNOTIFY: FILESYSTEM NOTIFICATION INFRASTRUCTURE
 M:	Jan Kara <jack@suse.cz>
 R:	Amir Goldstein <amir73il@gmail.com>
-- 
1.8.3.1

Re: [PATCH v11 5/8] i2c: fsi: Add transfer implementation

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 415 bytes --]


> +	cmd |= FIELD_PREP(I2C_CMD_ADDR, msg->addr >> 1);

I just noticed this and wonder: Don't you need the LSB of the address?
It is not the RW flag, this is encoded in msg->flags.

Also, no seperate handling for 10 bit addresses? Technically, 7-bit 0x50
is different on the wire from 10-bit 0x050. This is minor, though. There
are no 10-bit devices out there. Still, did you test 10-bit support?

Rest looks good.


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Re: [PATCH v11 5/8] i2c: fsi: Add transfer implementation

[Eddie James]

On 07/09/2018 05:41 PM, Wolfram Sang wrote:
>> +	cmd |= FIELD_PREP(I2C_CMD_ADDR, msg->addr >> 1);
> I just noticed this and wonder: Don't you need the LSB of the address?
> It is not the RW flag, this is encoded in msg->flags.

So, the hardware interprets the LSB as the RW flag. It wouldn't be 
possible to have a device addressed with the LSB set on this I2C master.

>
> Also, no seperate handling for 10 bit addresses? Technically, 7-bit 0x50
> is different on the wire from 10-bit 0x050. This is minor, though. There
> are no 10-bit devices out there. Still, did you test 10-bit support?

Indeed, real 10-bit addresses require some additional manipulation of 
this I2C master in order to work. We don't support it right now.

Thanks,
Eddie

>
> Rest looks good.
>

Re: [PATCH v11 5/8] i2c: fsi: Add transfer implementation

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 694 bytes --]


> > > +	cmd |= FIELD_PREP(I2C_CMD_ADDR, msg->addr >> 1);
> > I just noticed this and wonder: Don't you need the LSB of the address?
> > It is not the RW flag, this is encoded in msg->flags.
> 
> So, the hardware interprets the LSB as the RW flag. It wouldn't be possible
> to have a device addressed with the LSB set on this I2C master.

But msg->addr is 7 bit and LSB aligned. If I am not horribly wrong, with
the above code, an EEPROM at 0x50 would show up as 0x28 with your
driver?

> Indeed, real 10-bit addresses require some additional manipulation of this
> I2C master in order to work. We don't support it right now.

Then you should remove the associated FUNC flag.


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Re: [PATCH v11 5/8] i2c: fsi: Add transfer implementation

[Eddie James]

On 07/10/2018 01:50 PM, Wolfram Sang wrote:
>>>> +	cmd |= FIELD_PREP(I2C_CMD_ADDR, msg->addr >> 1);
>>> I just noticed this and wonder: Don't you need the LSB of the address?
>>> It is not the RW flag, this is encoded in msg->flags.
>> So, the hardware interprets the LSB as the RW flag. It wouldn't be possible
>> to have a device addressed with the LSB set on this I2C master.
> But msg->addr is 7 bit and LSB aligned. If I am not horribly wrong, with
> the above code, an EEPROM at 0x50 would show up as 0x28 with your
> driver?

Sorry, what do you mean "show up as"? Yes, we could first shift all our 
addresses in user-space before passing them to the driver, so that the 
msg->addr field is exactly what the hardware expects already... This 
would be non-trivial for our users considering all our documentation 
represents the addresses as the top 7 bits of a byte :(

>
>> Indeed, real 10-bit addresses require some additional manipulation of this
>> I2C master in order to work. We don't support it right now.
> Then you should remove the associated FUNC flag.

Ah, but due to the addressing situation, tools like i2cget don't work 
with our addresses unless the 10 bit flag is specified. For example, we 
may want to access 0xA0.

>

Re: [PATCH v11 5/8] i2c: fsi: Add transfer implementation

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 1474 bytes --]


> Sorry, what do you mean "show up as"? Yes, we could first shift all our
> addresses in user-space before passing them to the driver, so that the
> msg->addr field is exactly what the hardware expects already... This would
> be non-trivial for our users considering all our documentation represents
> the addresses as the top 7 bits of a byte :(

Ah, now I understand the whole situation! Good that I asked. But I have
bad news for you:

msg->addr is 7 bit and LSB aligned. No way around that. This is how
Linux I2C worked since the beginning. You have to adapt to it.

I know what you mean. Most doumentation I get has the addresses in 8
bit, i.e. 7 bit address shifted + RW bit. But sorry again, the Linux
representation is different and all drivers have to adhere to that.

An EEPROM ist at 0x50 in Linux. There is no write addr 0xa0 and read
addr 0xa1.

> > > Indeed, real 10-bit addresses require some additional manipulation of this
> > > I2C master in order to work. We don't support it right now.
> > Then you should remove the associated FUNC flag.
> 
> Ah, but due to the addressing situation, tools like i2cget don't work with
> our addresses unless the 10 bit flag is specified. For example, we may want
> to access 0xA0.

This is a kinda dirty workaround to the above problem. It is even wrong
because 10-bit addresses look totally different on the wire.

Sorry for the hazzle with the docs, but there is no way around that.


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Re: [PATCH v11 5/8] i2c: fsi: Add transfer implementation

[Eddie James]

On 07/10/2018 02:39 PM, Wolfram Sang wrote:
>> Sorry, what do you mean "show up as"? Yes, we could first shift all our
>> addresses in user-space before passing them to the driver, so that the
>> msg->addr field is exactly what the hardware expects already... This would
>> be non-trivial for our users considering all our documentation represents
>> the addresses as the top 7 bits of a byte :(
> Ah, now I understand the whole situation! Good that I asked. But I have
> bad news for you:
>
> msg->addr is 7 bit and LSB aligned. No way around that. This is how
> Linux I2C worked since the beginning. You have to adapt to it.
>
> I know what you mean. Most doumentation I get has the addresses in 8
> bit, i.e. 7 bit address shifted + RW bit. But sorry again, the Linux
> representation is different and all drivers have to adhere to that.
>
> An EEPROM ist at 0x50 in Linux. There is no write addr 0xa0 and read
> addr 0xa1.

OK, I understand! Will test and resend with conforming addressing. 
Thanks for all the feedback!

Eddie

>
>>>> Indeed, real 10-bit addresses require some additional manipulation of this
>>>> I2C master in order to work. We don't support it right now.
>>> Then you should remove the associated FUNC flag.
>> Ah, but due to the addressing situation, tools like i2cget don't work with
>> our addresses unless the 10 bit flag is specified. For example, we may want
>> to access 0xA0.
> This is a kinda dirty workaround to the above problem. It is even wrong
> because 10-bit addresses look totally different on the wire.
>
> Sorry for the hazzle with the docs, but there is no way around that.
>

Re: [PATCH v11 5/8] i2c: fsi: Add transfer implementation

[Benjamin Herrenschmidt]

On Tue, 2018-07-10 at 12:52 -0500, Eddie James wrote:
> 
> On 07/09/2018 05:41 PM, Wolfram Sang wrote:
> > > +	cmd |= FIELD_PREP(I2C_CMD_ADDR, msg->addr >> 1);
> > 
> > I just noticed this and wonder: Don't you need the LSB of the address?
> > It is not the RW flag, this is encoded in msg->flags.
> 
> So, the hardware interprets the LSB as the RW flag. It wouldn't be 
> possible to have a device addressed with the LSB set on this I2C master.

What do you mean ? That doesn't sound right... 
> 
> > 
> > Also, no seperate handling for 10 bit addresses? Technically, 7-bit 0x50
> > is different on the wire from 10-bit 0x050. This is minor, though. There
> > are no 10-bit devices out there. Still, did you test 10-bit support?
> 
> Indeed, real 10-bit addresses require some additional manipulation of 
> this I2C master in order to work. We don't support it right now.
> 
> Thanks,
> Eddie
> 
> > 
> > Rest looks good.
> > 

Re: [PATCH v11 5/8] i2c: fsi: Add transfer implementation

[Joel Stanley]

On 11 July 2018 at 06:59, Eddie James <eajames@linux.vnet.ibm.com> wrote:
>
>
> On 07/10/2018 02:39 PM, Wolfram Sang wrote:
>>>
>>> Sorry, what do you mean "show up as"? Yes, we could first shift all our
>>> addresses in user-space before passing them to the driver, so that the
>>> msg->addr field is exactly what the hardware expects already... This
>>> would
>>> be non-trivial for our users considering all our documentation represents
>>> the addresses as the top 7 bits of a byte :(
>>
>> Ah, now I understand the whole situation! Good that I asked. But I have
>> bad news for you:
>>
>> msg->addr is 7 bit and LSB aligned. No way around that. This is how
>> Linux I2C worked since the beginning. You have to adapt to it.
>>
>> I know what you mean. Most doumentation I get has the addresses in 8
>> bit, i.e. 7 bit address shifted + RW bit. But sorry again, the Linux
>> representation is different and all drivers have to adhere to that.
>>
>> An EEPROM ist at 0x50 in Linux. There is no write addr 0xa0 and read
>> addr 0xa1.
>
>
> OK, I understand! Will test and resend with conforming addressing. Thanks
> for all the feedback!

Nice one Wolfram. I wondered why the standard tools didn't work, but
hadn't gotten around to working out what was going on.

Thanks for taking a close look.

Cheers,

Joel

Re: [PATCH v11 5/8] i2c: fsi: Add transfer implementation

[Wolfram Sang]

[-- Attachment #1: Type: text/plain, Size: 616 bytes --]

Hi Joel,

> >> An EEPROM ist at 0x50 in Linux. There is no write addr 0xa0 and read
> >> addr 0xa1.
> >
> > OK, I understand! Will test and resend with conforming addressing. Thanks
> > for all the feedback!
> 
> Nice one Wolfram. I wondered why the standard tools didn't work, but
> hadn't gotten around to working out what was going on.

Still, a report that the standard tools don't work with the driver would
have been very helpful already. We can then work together what is the
reason. Please do next time.

> Thanks for taking a close look.

You are welcome.

Kind regards,

   Wolfram


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