fsi: Add IBM I2C Responder virtual FSI master

The I2C Responder translates I2C commands to CFAM or SCOM operations, effectively implementing an FSI master.

Signed-off-by Eddie James <[email protected]>

---
 .../devicetree/bindings/fsi/ibm,i2cr.yaml     | 42 +++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml

Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml new file +13 -0

new file mode 100644
index 000000000000..929ca10988f9
@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/fsi/ibm,i2cr.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: IBM I2C Responder virtual FSI master
+
+maintainers:
+  - Eddie James <[email protected]>
+
+description: |
+  This binding describes an I2C device called the I2C Responder 

(I2CR). The
+ I2CR translates commands sent over I2C bus to FSI CFAM reads and writes or
+ SCOM operations. The CFAM access means that the I2CR can act as an FSI

Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml new file +8 -0

+
+   reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+

Quoted 35 lines · Eddie James

The I2C Responder translates I2C commands to CFAM or SCOM operations, effectively implementing an FSI master.

Signed-off-by Eddie James <[email protected]>

---
  .../devicetree/bindings/fsi/ibm,i2cr.yaml     | 42 +++++++++++++++++++
  1 file changed, 42 insertions(+)

create mode 100644 Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml

Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml new file +13 -0

new file mode 100644
index 000000000000..929ca10988f9
@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/fsi/ibm,i2cr.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: IBM I2C Responder virtual FSI master
+
+maintainers:
+  - Eddie James <[email protected]>
+
+description: |
+  This binding describes an I2C device called the I2C Responder

(I2CR). The
+ I2CR translates commands sent over I2C bus to FSI CFAM reads and writes or
+ SCOM operations. The CFAM access means that the I2CR can act as an FSI
+ master.

Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml line 21

Quoted 5 lines

Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml new file +5 -0

+
+properties:
+  compatible:
+    enum:
+      - ibm,i2cr

I think this should be a bit more descriptive and at least mention that it's FSI-related, e.g. ibm,fsi-i2cr? Thoughts?

Quoted 9 lines

Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml new file +8 -0

+
+   reg:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+

Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml line 39

Quoted 10 lines

Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml new file +10 -0

+additionalProperties: false
+
+examples:
+ - |
+    i2c {
+      #address-cells = <1>;
+      #size-cells = <0>;
+
+      i2cr@20 {
+        compatible = "ibm,i2cr";

Change this in accordance with the above.

Andrew

The I2C Responder translates I2C commands to CFAM or SCOM operations, effectively implementing an FSI master.

Signed-off-by Eddie James <[email protected]>

---
 .../devicetree/bindings/fsi/ibm,i2cr.yaml     | 42 +++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml

The I2C Responder translates I2C commands to CFAM or SCOM operations, effectively implementing an FSI master.

Signed-off-by Eddie James <[email protected]>

---
 .../devicetree/bindings/fsi/ibm,i2cr.yaml     | 42 +++++++++++++++++++
 1 file changed, 42 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml

Documentation/devicetree/bindings/fsi/ibm,i2cr.yaml new file +3 -0

new file mode 100644
index 000000000000..929ca10988f9
@@ -0,0 +1,42 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---

The I2C Responder (I2CR) is an I2C device that translates I2C commands to CFAM or SCOM operations, effectively implementing an FSI master and bus.

Signed-off-by Eddie James <[email protected]>

---
 drivers/fsi/Kconfig                    |   9 +
 drivers/fsi/Makefile                   |   1 +
 drivers/fsi/fsi-master-i2cr.c          | 225 +++++++++++++++++++++++++
 include/trace/events/fsi_master_i2cr.h |  96 +++++++++++
 4 files changed, 331 insertions(+)
 create mode 100644 drivers/fsi/fsi-master-i2cr.c
 create mode 100644 include/trace/events/fsi_master_i2cr.h

drivers/fsi/Kconfig +9 -0

index e6668a869913..999be82720c5 100644
@@ -62,6 +62,15 @@ config FSI_MASTER_ASPEED
 
 	 Enable it for your BMC kernel in an OpenPower or IBM Power system.
 
+config FSI_MASTER_I2CR
+	tristate "IBM I2C Responder virtual FSI master"
+	depends on I2C
+	help
+	  This option enables a virtual FSI master in order to access a CFAM
+	  behind an IBM I2C Responder (I2CR) chip. The I2CR is an I2C device
+	  that translates I2C commands to CFAM or SCOM operations, effectively
+	  implementing an FSI master and bus.
+
 config FSI_SCOM
 	tristate "SCOM FSI client device driver"
 	help

drivers/fsi/Makefile +1 -0

index da218a1ad8e1..34dbaa1c452e 100644
@@ -4,6 +4,7 @@ obj-$(CONFIG_FSI) += fsi-core.o
 obj-$(CONFIG_FSI_MASTER_HUB) += fsi-master-hub.o
 obj-$(CONFIG_FSI_MASTER_ASPEED) += fsi-master-aspeed.o
 obj-$(CONFIG_FSI_MASTER_GPIO) += fsi-master-gpio.o
+obj-$(CONFIG_FSI_MASTER_I2CR) += fsi-master-i2cr.o
 obj-$(CONFIG_FSI_MASTER_AST_CF) += fsi-master-ast-cf.o
 obj-$(CONFIG_FSI_SCOM) += fsi-scom.o
 obj-$(CONFIG_FSI_SBEFIFO) += fsi-sbefifo.o

drivers/fsi/fsi-master-i2cr.c new file +54 -0

new file mode 100644
index 000000000000..d19ac96c0a83
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) IBM Corporation 2023 */
+
+#include <linux/device.h>
+#include <linux/fsi.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/mutex.h>
+
+#include "fsi-master.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/fsi_master_i2cr.h>
+
+#define I2CR_ADDRESS_CFAM(a)	((a) >> 2)
+#define I2CR_STATUS		0x30001
+#define  I2CR_STATUS_ERR	 BIT_ULL(61)
+#define I2CR_ERROR		0x30002
+
+struct fsi_master_i2cr {
+	struct fsi_master master;
+	struct mutex lock;	/* protect HW access */
+	struct i2c_client *client;
+};
+
+static bool i2cr_check_parity(u32 v, bool parity)
+{
+	u32 i;
+
+	for (i = 0; i < 32; ++i) {
+		if (v & (1 << i))
+			parity = !parity;
+	}
+
+	return parity;
+}
+
+static __be32 i2cr_get_command(u32 address, bool parity)
+{
+	__be32 command;
+
+	address <<= 1;
+
+	if (i2cr_check_parity(address, parity))
+		address |= 1;
+
+	command = cpu_to_be32(address);
+	trace_i2cr_command((__force uint32_t)command);
+
+	return command;
+}
+
+static int i2cr_transfer(struct i2c_client *client, u32 address, 

__be64 *data)

drivers/fsi/fsi-master-i2cr.c new file +46 -0

+{
+	struct i2c_msg msgs[2];
+	__be32 command;
+	int ret;
+
+	command = i2cr_get_command(address, true);
+	msgs[0].addr = client->addr;
+	msgs[0].flags = 0;
+	msgs[0].len = sizeof(command);
+	msgs[0].buf = (__u8 *)&command;
+	msgs[1].addr = client->addr;
+	msgs[1].flags = I2C_M_RD;
+	msgs[1].len = sizeof(*data);
+	msgs[1].buf = (__u8 *)data;
+
+	ret = i2c_transfer(client->adapter, msgs, 2);
+	if (ret == 2)
+		return 0;
+
+	trace_i2cr_i2c_error(ret);
+
+	if (ret < 0)
+		return ret;
+
+	return -EIO;
+}
+
+static int i2cr_check_status(struct i2c_client *client)
+{
+	__be64 status_be = 0;
+	u64 status;
+	int ret;
+
+	ret = i2cr_transfer(client, I2CR_STATUS, &status_be);
+	if (ret)
+		return ret;
+
+	status = be64_to_cpu(status_be);
+	if (status & I2CR_STATUS_ERR) {
+		__be64 error_be = 0;
+		u64 error;
+
+		i2cr_transfer(client, I2CR_ERROR, &error_be);
+		error = be64_to_cpu(error_be);
+		trace_i2cr_status_error(status, error);
+		dev_err(&client->dev, "status:%016llx error:%016llx\n", status, 

error);

drivers/fsi/fsi-master-i2cr.c new file +8 -0

+		return -EREMOTEIO;
+	}
+
+	trace_i2cr_status(status);
+	return 0;
+}
+
+static int i2cr_read(struct fsi_master *master, int link, uint8_t id, 

uint32_t addr, void *val,

drivers/fsi/fsi-master-i2cr.c new file +3 -0

+		     size_t size)
+{
+	struct fsi_master_i2cr *i2cr = container_of(master, struct 

fsi_master_i2cr, master);

drivers/fsi/fsi-master-i2cr.c new file +4 -0

+	__be64 data = 0;
+	int ret;
+
+	if (link || id || (addr & 0xffff0000) || !size || size > 4 || size == 

3)

drivers/fsi/fsi-master-i2cr.c new file +21 -0

+		return -EINVAL;
+
+	mutex_lock(&i2cr->lock);
+
+	ret = i2cr_transfer(i2cr->client, I2CR_ADDRESS_CFAM(addr), &data);
+	if (ret)
+		goto unlock;
+
+	ret = i2cr_check_status(i2cr->client);
+	if (ret)
+		goto unlock;
+
+	trace_i2cr_read(addr, size, (__force uint32_t)data);
+	memcpy(val, &data, size);
+
+unlock:
+	mutex_unlock(&i2cr->lock);
+	return ret;
+}
+
+static int i2cr_write(struct fsi_master *master, int link, uint8_t id, 

uint32_t addr,

drivers/fsi/fsi-master-i2cr.c new file +3 -0

+		      const void *val, size_t size)
+{
+	struct fsi_master_i2cr *i2cr = container_of(master, struct 

fsi_master_i2cr, master);

drivers/fsi/fsi-master-i2cr.c new file +4 -0

+	__be32 data[3];
+	int ret;
+
+	if (link || id || (addr & 0xffff0000) || !size || size > 4 || size == 

3)

drivers/fsi/fsi-master-i2cr.c new file +5 -0

+		return -EINVAL;
+
+	data[1] = 0;
+	memcpy(&data[1], val, size);
+	data[0] = i2cr_get_command(I2CR_ADDRESS_CFAM(addr),

drivers/fsi/fsi-master-i2cr.c new file +39 -0

+	} else {
+		trace_i2cr_i2c_error(ret);
+
+		if (ret >= 0)
+			ret = -EIO;
+	}
+
+	mutex_unlock(&i2cr->lock);
+	return ret;
+}
+
+static int i2cr_probe(struct i2c_client *client)
+{
+	struct fsi_master_i2cr *i2cr;
+	int ret;
+
+	i2cr = devm_kzalloc(&client->dev, sizeof(*i2cr), GFP_KERNEL);
+	if (!i2cr)
+		return -ENOMEM;
+
+	i2cr->master.dev.parent = &client->dev;
+	i2cr->master.dev.of_node = of_node_get(dev_of_node(&client->dev));
+
+	i2cr->master.n_links = 1;
+	i2cr->master.read = i2cr_read;
+	i2cr->master.write = i2cr_write;
+
+	mutex_init(&i2cr->lock);
+	i2cr->client = client;
+
+	ret = fsi_master_register(&i2cr->master);
+	if (ret)
+		return ret;
+
+	i2c_set_clientdata(client, i2cr);
+	return 0;
+}
+
+static int i2cr_remove(struct i2c_client *client)

Quoted 103 lines · Eddie James

The I2C Responder (I2CR) is an I2C device that translates I2C commands to CFAM or SCOM operations, effectively implementing an FSI master and bus.

Signed-off-by Eddie James <[email protected]>

---
  drivers/fsi/Kconfig                    |   9 +
  drivers/fsi/Makefile                   |   1 +
  drivers/fsi/fsi-master-i2cr.c          | 225 +++++++++++++++++++++++++
  include/trace/events/fsi_master_i2cr.h |  96 +++++++++++
  4 files changed, 331 insertions(+)

create mode 100644 drivers/fsi/fsi-master-i2cr.c create mode 100644 include/trace/events/fsi_master_i2cr.h

drivers/fsi/Kconfig +9 -0

index e6668a869913..999be82720c5 100644
@@ -62,6 +62,15 @@ config FSI_MASTER_ASPEED
 
  	 Enable it for your BMC kernel in an OpenPower or IBM Power system.
 
+config FSI_MASTER_I2CR
+	tristate "IBM I2C Responder virtual FSI master"
+	depends on I2C
+	help
+	  This option enables a virtual FSI master in order to access a CFAM
+	  behind an IBM I2C Responder (I2CR) chip. The I2CR is an I2C device
+	  that translates I2C commands to CFAM or SCOM operations, effectively
+	  implementing an FSI master and bus.
+
  config FSI_SCOM
  	tristate "SCOM FSI client device driver"
  	help

drivers/fsi/Makefile +1 -0

index da218a1ad8e1..34dbaa1c452e 100644
@@ -4,6 +4,7 @@ obj-$(CONFIG_FSI) += fsi-core.o
  obj-$(CONFIG_FSI_MASTER_HUB) += fsi-master-hub.o
  obj-$(CONFIG_FSI_MASTER_ASPEED) += fsi-master-aspeed.o
  obj-$(CONFIG_FSI_MASTER_GPIO) += fsi-master-gpio.o
+obj-$(CONFIG_FSI_MASTER_I2CR) += fsi-master-i2cr.o
  obj-$(CONFIG_FSI_MASTER_AST_CF) += fsi-master-ast-cf.o
  obj-$(CONFIG_FSI_SCOM) += fsi-scom.o
  obj-$(CONFIG_FSI_SBEFIFO) += fsi-sbefifo.o

drivers/fsi/fsi-master-i2cr.c new file +50 -0

new file mode 100644
index 000000000000..d19ac96c0a83
@@ -0,0 +1,225 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (C) IBM Corporation 2023 */
+
+#include <linux/device.h>
+#include <linux/fsi.h>
+#include <linux/i2c.h>
+#include <linux/module.h>
+#include <linux/mod_devicetable.h>
+#include <linux/mutex.h>
+
+#include "fsi-master.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/fsi_master_i2cr.h>
+
+#define I2CR_ADDRESS_CFAM(a)	((a) >> 2)
+#define I2CR_STATUS		0x30001
+#define  I2CR_STATUS_ERR	 BIT_ULL(61)
+#define I2CR_ERROR		0x30002
+
+struct fsi_master_i2cr {
+	struct fsi_master master;
+	struct mutex lock;	/* protect HW access */
+	struct i2c_client *client;
+};
+
+static bool i2cr_check_parity(u32 v, bool parity)
+{
+	u32 i;
+
+	for (i = 0; i < 32; ++i) {
+		if (v & (1 << i))
+			parity = !parity;
+	}
+
+	return parity;
+}
+
+static __be32 i2cr_get_command(u32 address, bool parity)
+{
+	__be32 command;
+
+	address <<= 1;
+
+	if (i2cr_check_parity(address, parity))
+		address |= 1;
+
+	command = cpu_to_be32(address);
+	trace_i2cr_command((__force uint32_t)command);
+

Quoted 5 lines

drivers/fsi/fsi-master-i2cr.c new file +4 -0

+	return command;
+}
+
+static int i2cr_transfer(struct i2c_client *client, u32 address,

__be64 *data)

Is there a reason to use __be64 *data here and not void *data, size_t len? We never actually use it as the declared type internally, only cast it to __u8 *.

Quoted 60 lines

drivers/fsi/fsi-master-i2cr.c new file +46 -0

+{
+	struct i2c_msg msgs[2];
+	__be32 command;
+	int ret;
+
+	command = i2cr_get_command(address, true);
+	msgs[0].addr = client->addr;
+	msgs[0].flags = 0;
+	msgs[0].len = sizeof(command);
+	msgs[0].buf = (__u8 *)&command;
+	msgs[1].addr = client->addr;
+	msgs[1].flags = I2C_M_RD;
+	msgs[1].len = sizeof(*data);
+	msgs[1].buf = (__u8 *)data;
+
+	ret = i2c_transfer(client->adapter, msgs, 2);
+	if (ret == 2)
+		return 0;
+
+	trace_i2cr_i2c_error(ret);
+
+	if (ret < 0)
+		return ret;
+
+	return -EIO;
+}
+
+static int i2cr_check_status(struct i2c_client *client)
+{
+	__be64 status_be = 0;
+	u64 status;
+	int ret;
+
+	ret = i2cr_transfer(client, I2CR_STATUS, &status_be);
+	if (ret)
+		return ret;
+
+	status = be64_to_cpu(status_be);
+	if (status & I2CR_STATUS_ERR) {
+		__be64 error_be = 0;
+		u64 error;
+
+		i2cr_transfer(client, I2CR_ERROR, &error_be);
+		error = be64_to_cpu(error_be);
+		trace_i2cr_status_error(status, error);
+		dev_err(&client->dev, "status:%016llx error:%016llx\n", status,

error);

drivers/fsi/fsi-master-i2cr.c new file +8 -0

+		return -EREMOTEIO;
+	}
+
+	trace_i2cr_status(status);
+	return 0;
+}
+
+static int i2cr_read(struct fsi_master *master, int link, uint8_t id,

uint32_t addr, void *val,

drivers/fsi/fsi-master-i2cr.c new file +3 -0

+		     size_t size)
+{
+	struct fsi_master_i2cr *i2cr = container_of(master, struct

Quoted 6 lines

fsi_master_i2cr, master);

drivers/fsi/fsi-master-i2cr.c new file +4 -0

+	__be64 data = 0;
+	int ret;
+
+	if (link || id || (addr & 0xffff0000) || !size || size > 4 || size ==

3)

These size constraints are a bit funky. Instead of !size || size > 4 || size == 3 we write !(size == 1 || size == 2 || size == 4)?

Quoted 31 lines

drivers/fsi/fsi-master-i2cr.c new file +21 -0

+		return -EINVAL;
+
+	mutex_lock(&i2cr->lock);
+
+	ret = i2cr_transfer(i2cr->client, I2CR_ADDRESS_CFAM(addr), &data);
+	if (ret)
+		goto unlock;
+
+	ret = i2cr_check_status(i2cr->client);
+	if (ret)
+		goto unlock;
+
+	trace_i2cr_read(addr, size, (__force uint32_t)data);
+	memcpy(val, &data, size);
+
+unlock:
+	mutex_unlock(&i2cr->lock);
+	return ret;
+}
+
+static int i2cr_write(struct fsi_master *master, int link, uint8_t id,

uint32_t addr,

drivers/fsi/fsi-master-i2cr.c new file +3 -0

+		      const void *val, size_t size)
+{
+	struct fsi_master_i2cr *i2cr = container_of(master, struct

fsi_master_i2cr, master);

drivers/fsi/fsi-master-i2cr.c new file +4 -0

+	__be32 data[3];
+	int ret;
+
+	if (link || id || (addr & 0xffff0000) || !size || size > 4 || size ==

Quoted 1 line

3)

As above

Quoted 5 lines

drivers/fsi/fsi-master-i2cr.c new file +5 -0

+		return -EINVAL;
+
+	data[1] = 0;
+	memcpy(&data[1], val, size);
+	data[0] = i2cr_get_command(I2CR_ADDRESS_CFAM(addr),

drivers/fsi/fsi-master-i2cr.c line 158

Quoted 10 lines

drivers/fsi/fsi-master-i2cr.c new file +10 -0

+				   i2cr_check_parity((__force u32)data[1], true));
+	data[2] = 0;
+
+	mutex_lock(&i2cr->lock);
+
+	ret = i2c_master_send(i2cr->client, (const char *)data, sizeof(data));
+	if (ret == sizeof(data)) {
+		ret = i2cr_check_status(i2cr->client);
+		if (!ret)
+			trace_i2cr_write(addr, size, (__force uint32_t)data[1]);

I think we can reduce the amount of __force if we flip the endianness of the data variable?

```
u32 data[3];
__be32 cmd_be;

data[1] = 0;
memcpy(&data[1], val, size);
cmd_be = i2cr_get_command(I2CR_ADDRESS_CFAM(addr),
						    i2cr_check_parity(data[1], true));
data[0] = (__force u32)cmd_be;
data[2] = 0;
....
trace_i2cr_write(addr, size, data[1]);
```

?

Or define i2cr_check_parity() and the tracepoint in terms of big-endian?

Quoted 43 lines

drivers/fsi/fsi-master-i2cr.c new file +42 -0

+	} else {
+		trace_i2cr_i2c_error(ret);
+
+		if (ret >= 0)
+			ret = -EIO;
+	}
+
+	mutex_unlock(&i2cr->lock);
+	return ret;
+}
+
+static int i2cr_probe(struct i2c_client *client)
+{
+	struct fsi_master_i2cr *i2cr;
+	int ret;
+
+	i2cr = devm_kzalloc(&client->dev, sizeof(*i2cr), GFP_KERNEL);
+	if (!i2cr)
+		return -ENOMEM;
+
+	i2cr->master.dev.parent = &client->dev;
+	i2cr->master.dev.of_node = of_node_get(dev_of_node(&client->dev));
+
+	i2cr->master.n_links = 1;
+	i2cr->master.read = i2cr_read;
+	i2cr->master.write = i2cr_write;
+
+	mutex_init(&i2cr->lock);
+	i2cr->client = client;
+
+	ret = fsi_master_register(&i2cr->master);
+	if (ret)
+		return ret;
+
+	i2c_set_clientdata(client, i2cr);
+	return 0;
+}
+
+static int i2cr_remove(struct i2c_client *client)
+{
+	struct fsi_master_i2cr *i2cr = i2c_get_clientdata(client);
+

drivers/fsi/fsi-master-i2cr.c line 207

Quoted 7 lines

drivers/fsi/fsi-master-i2cr.c new file +7 -0

+	fsi_master_unregister(&i2cr->master);
+
+	return 0;
+}
+
+static const struct of_device_id i2cr_i2c_ids[] = {
+	{ .compatible = "ibm,i2cr", },

This may need an update after discussion on the binding patch.

Andrew