[PATCH v1 5/6] misc: amd-sbi: Add SBTSI ioctl register transfer interface

[Akshay Gupta <Akshay.Gupta@amd.com>]

From: Prathima <Prathima.Lk@amd.com>

Implement IOCTL interface for SB-TSI driver to enable userspace access
to TSI register read/write operations through the AMD Advanced Platform
Management Link (APML) protocol.

Reviewed-by: Akshay Gupta <Akshay.Gupta@amd.com>
Signed-off-by: Prathima <Prathima.Lk@amd.com>
---
 drivers/misc/amd-sbi/tsi-core.c | 86 ++++++++++++++++++++++++++++++++-
 drivers/misc/amd-sbi/tsi-core.h |  5 ++
 drivers/misc/amd-sbi/tsi.c      | 37 ++++++++++++--
 include/uapi/misc/amd-apml.h    | 23 +++++++++
 4 files changed, 146 insertions(+), 5 deletions(-)

diff --git a/drivers/misc/amd-sbi/tsi-core.c b/drivers/misc/amd-sbi/tsi-core.c
index fcb7fcf87a55..080cf1f368df 100644
--- a/drivers/misc/amd-sbi/tsi-core.c
+++ b/drivers/misc/amd-sbi/tsi-core.c
@@ -6,6 +6,10 @@
  * Copyright (c) 2020, Kun Yi <kunyi@google.com>
  */
 
+#include <linux/fs.h>
+#include <linux/ioctl.h>
+#include <linux/uaccess.h>
+#include <uapi/misc/amd-apml.h>
 #include "tsi-core.h"
 
 /* I3C read transfer function */
@@ -56,9 +60,87 @@ static int sbtsi_i2c_xfer(struct sbtsi_data *data, u8 reg, u8 *val, bool is_read
 /* Unified transfer function for I2C and I3C access */
 int sbtsi_xfer(struct sbtsi_data *data, u8 reg, u8 *val, bool is_read)
 {
+	int ret;
+
+	mutex_lock(&data->lock);
 	if (data->is_i3c)
-		return is_read ? sbtsi_i3c_read(data, reg, val)
+		ret = is_read ? sbtsi_i3c_read(data, reg, val)
 			: sbtsi_i3c_write(data, reg, val);
+	else
+		ret = sbtsi_i2c_xfer(data, reg, val, is_read);
+	mutex_unlock(&data->lock);
+	return ret;
+}
+
+static int apml_tsi_reg_xfer(struct sbtsi_data *data,
+			     struct apml_tsi_xfer_msg __user *arg)
+{
+	struct apml_tsi_xfer_msg msg = { 0 };
+	u8 val;
+	int ret;
+
+	/* Copy the structure from user */
+	if (copy_from_user(&msg, arg, sizeof(struct apml_tsi_xfer_msg)))
+		return -EFAULT;
+
+	if (msg.rflag) {
+		/* Read operation */
+		ret = sbtsi_xfer(data, msg.reg_addr, &val, true);
+		if (!ret)
+			msg.data_in_out = val;
+	} else {
+		/* Write operation */
+		ret = sbtsi_xfer(data, msg.reg_addr, &msg.data_in_out, false);
+	}
+
+	if (msg.rflag && !ret) {
+		if (copy_to_user(arg, &msg, sizeof(struct apml_tsi_xfer_msg)))
+			return -EFAULT;
+	}
+	return ret;
+}
+
+static long sbtsi_ioctl(struct file *fp, unsigned int cmd, unsigned long arg)
+{
+	void __user *argp = (void __user *)arg;
+	struct sbtsi_data *data;
+
+	data = container_of(fp->private_data, struct sbtsi_data, sbtsi_misc_dev);
+	switch (cmd) {
+	case SBTSI_IOCTL_REG_XFER_CMD:
+		return apml_tsi_reg_xfer(data, argp);
+	default:
+		return -ENOTTY;
+	}
+}
+
+static const struct file_operations sbtsi_fops = {
+	.owner          = THIS_MODULE,
+	.unlocked_ioctl = sbtsi_ioctl,
+	.compat_ioctl   = compat_ptr_ioctl,
+};
+
+int create_misc_tsi_device(struct sbtsi_data *data,
+			   struct device *dev)
+{
+	int ret;
+
+	data->sbtsi_misc_dev.name            = devm_kasprintf(dev, GFP_KERNEL,
+							      "sbtsi-%x", data->dev_addr);
+	if (!data->sbtsi_misc_dev.name)
+		return -ENOMEM;
+	data->sbtsi_misc_dev.minor           = MISC_DYNAMIC_MINOR;
+	data->sbtsi_misc_dev.fops            = &sbtsi_fops;
+	data->sbtsi_misc_dev.parent          = dev;
+	data->sbtsi_misc_dev.nodename        = devm_kasprintf(dev, GFP_KERNEL,
+							      "sbtsi-%x", data->dev_addr);
+	if (!data->sbtsi_misc_dev.nodename)
+		return -ENOMEM;
+	data->sbtsi_misc_dev.mode            = 0600;
+
+	ret = misc_register(&data->sbtsi_misc_dev);
+	if (ret)
+		return ret;
 
-	return sbtsi_i2c_xfer(data, reg, val, is_read);
+	return ret;
 }
diff --git a/drivers/misc/amd-sbi/tsi-core.h b/drivers/misc/amd-sbi/tsi-core.h
index a4ded17942c9..d130ceadde04 100644
--- a/drivers/misc/amd-sbi/tsi-core.h
+++ b/drivers/misc/amd-sbi/tsi-core.h
@@ -9,6 +9,7 @@
 #include <linux/err.h>
 #include <linux/i2c.h>
 #include <linux/init.h>
+#include <linux/miscdevice.h>
 #include <linux/module.h>
 #include <linux/of.h>
 #include <linux/types.h>
@@ -21,12 +22,16 @@ struct sbtsi_data {
 		struct i2c_client *client;
 		struct i3c_device *i3cdev;
 	};
+	struct miscdevice sbtsi_misc_dev;
+	struct mutex lock; /* serializes SBTSI register access */
 	bool ext_range_mode;
 	bool read_order;
 	bool is_i3c;
+	u8 dev_addr;
 };
 
 int sbtsi_xfer(struct sbtsi_data *data, u8 reg, u8 *val, bool is_read);
+int create_misc_tsi_device(struct sbtsi_data *data, struct device *dev);
 
 #ifdef CONFIG_AMD_SBTSI_HWMON
 int create_sbtsi_hwmon_sensor_device(struct device *dev, struct sbtsi_data *data);
diff --git a/drivers/misc/amd-sbi/tsi.c b/drivers/misc/amd-sbi/tsi.c
index d7a8237fc4fd..6e321064a3f3 100644
--- a/drivers/misc/amd-sbi/tsi.c
+++ b/drivers/misc/amd-sbi/tsi.c
@@ -38,6 +38,7 @@ static int sbtsi_i2c_probe(struct i2c_client *client)
 
 	data->is_i3c = false;
 	data->client = client;
+	mutex_init(&data->lock);
 	err = i2c_smbus_read_byte_data(data->client, SBTSI_REG_CONFIG);
 	if (err < 0)
 		return err;
@@ -45,7 +46,21 @@ static int sbtsi_i2c_probe(struct i2c_client *client)
 	data->read_order = FIELD_GET(BIT(SBTSI_CONFIG_READ_ORDER_SHIFT), err);
 
 	dev_set_drvdata(dev, data);
-	return create_sbtsi_hwmon_sensor_device(dev, data);
+	err = create_sbtsi_hwmon_sensor_device(dev, data);
+	if (err < 0)
+		return err;
+	data->dev_addr = client->addr;
+	return create_misc_tsi_device(data, dev);
+}
+
+static void sbtsi_i2c_remove(struct i2c_client *client)
+{
+	struct sbtsi_data *data = dev_get_drvdata(&client->dev);
+
+	if (data)
+		misc_deregister(&data->sbtsi_misc_dev);
+
+	dev_info(&client->dev, "Removed sbtsi driver\n");
 }
 
 static const struct i2c_device_id sbtsi_id[] = {
@@ -68,6 +83,7 @@ static struct i2c_driver sbtsi_driver = {
 		.of_match_table = of_match_ptr(sbtsi_of_match),
 	},
 	.probe = sbtsi_i2c_probe,
+	.remove = sbtsi_i2c_remove,
 	.id_table = sbtsi_id,
 };
 
@@ -90,7 +106,7 @@ static int sbtsi_i3c_probe(struct i3c_device *i3cdev)
 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
 	if (!data)
 		return -ENOMEM;
-
+	mutex_init(&data->lock);
 	data->i3cdev = i3cdev;
 	data->is_i3c = true;
 
@@ -102,7 +118,21 @@ static int sbtsi_i3c_probe(struct i3c_device *i3cdev)
 	data->read_order = FIELD_GET(BIT(SBTSI_CONFIG_READ_ORDER_SHIFT), val);
 
 	dev_set_drvdata(dev, data);
-	return create_sbtsi_hwmon_sensor_device(dev, data);
+	err = create_sbtsi_hwmon_sensor_device(dev, data);
+	if (err < 0)
+		return err;
+	data->dev_addr = i3cdev->desc->info.dyn_addr;
+	return create_misc_tsi_device(data, dev);
+}
+
+static void sbtsi_i3c_remove(struct i3c_device *i3cdev)
+{
+	struct sbtsi_data *data = dev_get_drvdata(&i3cdev->dev);
+
+	if (data)
+		misc_deregister(&data->sbtsi_misc_dev);
+
+	dev_info(&i3cdev->dev, "Removed sbtsi-i3c driver\n");
 }
 
 static const struct i3c_device_id sbtsi_i3c_id[] = {
@@ -121,6 +151,7 @@ static struct i3c_driver sbtsi_i3c_driver = {
 		.name = "sbtsi-i3c",
 	},
 	.probe = sbtsi_i3c_probe,
+	.remove = sbtsi_i3c_remove,
 	.id_table = sbtsi_i3c_id,
 };
 
diff --git a/include/uapi/misc/amd-apml.h b/include/uapi/misc/amd-apml.h
index 745b3338fc06..199532b8e64a 100644
--- a/include/uapi/misc/amd-apml.h
+++ b/include/uapi/misc/amd-apml.h
@@ -73,6 +73,13 @@ struct apml_reg_xfer_msg {
 	__u8 rflag;
 };
 
+struct apml_tsi_xfer_msg {
+	__u8 reg_addr;	/* TSI register address offset */
+	__u8 data_in_out;	/* Register data for read/write */
+	__u8 rflag;	/* Register read or write */
+	__u8 pad;	/* Explicit padding */
+};
+
 /*
  * AMD sideband interface base IOCTL
  */
@@ -149,4 +156,20 @@ struct apml_reg_xfer_msg {
  */
 #define SBRMI_IOCTL_REG_XFER_CMD	_IOWR(SB_BASE_IOCTL_NR, 3, struct apml_reg_xfer_msg)
 
+/**
+ * DOC: SBTSI_IOCTL_REG_XFER_CMD
+ *
+ * @Parameters
+ *
+ * @struct apml_tsi_xfer_msg
+ *      Pointer to the &struct apml_tsi_xfer_msg that will contain the protocol
+ *      information
+ *
+ * @Description
+ * IOCTL command for APML TSI messages using generic _IOWR
+ * The IOCTL provides userspace access to AMD sideband TSI register xfer protocol
+ * - TSI protocol to read/write temperature sensor registers
+ */
+#define SBTSI_IOCTL_REG_XFER_CMD	_IOWR(SB_BASE_IOCTL_NR, 4, struct apml_tsi_xfer_msg)
+
 #endif /*_AMD_APML_H_*/
-- 
2.34.1