SB-TSI hwmon driver v4

SB Temperature Sensor Interface (SB-TSI) is an SMBus compatible interface that reports AMD SoC's Ttcl (normalized temperature), and resembles a typical 8-pin remote temperature sensor's I2C interface to BMC.

This commit adds basic support using this interface to read CPU temperature, and read/write high/low CPU temp thresholds.

To instantiate this driver on an AMD CPU with SB-TSI
support, the i2c bus number would be the bus connected from the board management controller (BMC) to the CPU. The i2c address is specified in Section 6.3.1 of the spec [1]: The SB-TSI address is normally 98h for socket 0 and 90h for socket 1, but it could vary based on hardware address select pins.

[1]: https://www.amd.com/system/files/TechDocs/56255_OSRR.pdf

Test status: tested reading temp1_input, and reading/writing temp1_max/min.

Signed-off-by Kun Yi <[email protected]>

---
 drivers/hwmon/Kconfig      |  10 ++
 drivers/hwmon/Makefile     |   1 +
 drivers/hwmon/sbtsi_temp.c | 265 +++++++++++++++++++++++++++++++++++++
 3 files changed, 276 insertions(+)
 create mode 100644 drivers/hwmon/sbtsi_temp.c

drivers/hwmon/Kconfig +10 -0

index 3c059fc23cd6..3d6a809700ae 100644
@@ -1522,6 +1522,16 @@ config SENSORS_SL28CPLD
 	  This driver can also be built as a module.  If so, the module
 	  will be called sl28cpld-hwmon.
 
+config SENSORS_SBTSI
+	tristate "Emulated SB-TSI temperature sensor"
+	depends on I2C
+	help
+	  If you say yes here you get support for emulated temperature
+	  sensors on AMD SoCs with SB-TSI interface connected to a BMC device.
+
+	  This driver can also be built as a module. If so, the module will
+	  be called sbtsi_temp.
+
 config SENSORS_SHT15
 	tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
 	depends on GPIOLIB || COMPILE_TEST

drivers/hwmon/Makefile +1 -0

index 01ca5d3fbad4..ee8c037919da 100644
@@ -160,6 +160,7 @@ obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
 obj-$(CONFIG_SENSORS_PWM_FAN)	+= pwm-fan.o
 obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON)	+= raspberrypi-hwmon.o
 obj-$(CONFIG_SENSORS_S3C)	+= s3c-hwmon.o
+obj-$(CONFIG_SENSORS_SBTSI)	+= sbtsi_temp.o
 obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
 obj-$(CONFIG_SENSORS_SCH5627)	+= sch5627.o
 obj-$(CONFIG_SENSORS_SCH5636)	+= sch5636.o

drivers/hwmon/sbtsi_temp.c new file +72 -0

new file mode 100644
index 000000000000..6b0a7b9df1f3
@@ -0,0 +1,265 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * sbtsi_temp.c - hwmon driver for a SBI Temperature Sensor Interface (SB-TSI)
+ *                compliant AMD SoC temperature device.
+ *
+ * Copyright (c) 2020, Google Inc.
+ * Copyright (c) 2020, Kun Yi <[email protected]>
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_device.h>
+#include <linux/of.h>
+
+/*
+ * SB-TSI registers only support SMBus byte data access. "_INT" registers are
+ * the integer part of a temperature value or limit, and "_DEC" registers are
+ * corresponding decimal parts.
+ */
+#define SBTSI_REG_TEMP_INT		0x01 /* RO */
+#define SBTSI_REG_STATUS		0x02 /* RO */
+#define SBTSI_REG_CONFIG		0x03 /* RO */
+#define SBTSI_REG_TEMP_HIGH_INT		0x07 /* RW */
+#define SBTSI_REG_TEMP_LOW_INT		0x08 /* RW */
+#define SBTSI_REG_TEMP_DEC		0x10 /* RW */
+#define SBTSI_REG_TEMP_HIGH_DEC		0x13 /* RW */
+#define SBTSI_REG_TEMP_LOW_DEC		0x14 /* RW */
+
+#define SBTSI_CONFIG_READ_ORDER_SHIFT	5
+
+#define SBTSI_TEMP_MIN	0
+#define SBTSI_TEMP_MAX	255875
+
+/* Each client has this additional data */
+struct sbtsi_data {
+	struct i2c_client *client;
+	struct mutex lock;
+};
+
+/*
+ * From SB-TSI spec: CPU temperature readings and limit registers encode the
+ * temperature in increments of 0.125 from 0 to 255.875. The "high byte"
+ * register encodes the base-2 of the integer portion, and the upper 3 bits of
+ * the "low byte" encode in base-2 the decimal portion.
+ *
+ * e.g. INT=0x19, DEC=0x20 represents 25.125 degrees Celsius
+ *
+ * Therefore temperature in millidegree Celsius =
+ *   (INT + DEC / 256) * 1000 = (INT * 8 + DEC / 32) * 125
+ */
+static inline int sbtsi_reg_to_mc(s32 integer, s32 decimal)
+{
+	return ((integer << 3) + (decimal >> 5)) * 125;
+}
+
+/*
+ * Inversely, given temperature in millidegree Celsius
+ *   INT = (TEMP / 125) / 8
+ *   DEC = ((TEMP / 125) % 8) * 32
+ * Caller have to make sure temp doesn't exceed 255875, the max valid value.
+ */
+static inline void sbtsi_mc_to_reg(s32 temp, u8 *integer, u8 *decimal)
+{
+	temp /= 125;
+	*integer = temp >> 3;
+	*decimal = (temp & 0x7) << 5;
+}
+

drivers/hwmon/sbtsi_temp.c new file +36 -0

+
+	reading_input = false;
+	switch (attr) {
+	case hwmon_temp_input:
+		reading_input = true;
+		/*
+		 * ReadOrder bit specifies the reading order of integer and
+		 * decimal part of CPU temp for atomic reads. If bit == 0,
+		 * reading integer part triggers latching of the decimal part,
+		 * so integer part should be read first. If bit == 1, read
+		 * order should be reversed.
+		 */
+		err = i2c_smbus_read_byte_data(data->client, SBTSI_REG_CONFIG);
+		if (err < 0)
+			return err;
+
+		mutex_lock(&data->lock);
+		if (err & BIT(SBTSI_CONFIG_READ_ORDER_SHIFT)) {
+			temp_dec = i2c_smbus_read_byte_data(data->client,
+							    SBTSI_REG_TEMP_DEC);
+			temp_int = i2c_smbus_read_byte_data(data->client,
+							    SBTSI_REG_TEMP_INT);
+		} else {
+			temp_int = i2c_smbus_read_byte_data(data->client,
+							    SBTSI_REG_TEMP_INT);
+			temp_dec = i2c_smbus_read_byte_data(data->client,
+							    SBTSI_REG_TEMP_DEC);
+		}
+		mutex_unlock(&data->lock);
+		break;
+	case hwmon_temp_max:
+		reg_int = SBTSI_REG_TEMP_HIGH_INT;
+		reg_dec = SBTSI_REG_TEMP_HIGH_DEC;
+		break;
+	case hwmon_temp_min:
+		reg_int = SBTSI_REG_TEMP_LOW_INT;

drivers/hwmon/sbtsi_temp.c new file +10 -0

+
+	if (temp_int < 0)
+		return temp_int;
+	if (temp_dec < 0)
+		return temp_dec;
+
+	*val = sbtsi_reg_to_mc(temp_int, temp_dec);
+
+	return 0;
+}

drivers/hwmon/sbtsi_temp.c new file +73 -0

+
+	switch (attr) {
+	case hwmon_temp_max:
+		reg_int = SBTSI_REG_TEMP_HIGH_INT;
+		reg_dec = SBTSI_REG_TEMP_HIGH_DEC;
+		break;
+	case hwmon_temp_min:
+		reg_int = SBTSI_REG_TEMP_LOW_INT;
+		reg_dec = SBTSI_REG_TEMP_LOW_DEC;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	val = clamp_val(val, SBTSI_TEMP_MIN, SBTSI_TEMP_MAX);
+	mutex_lock(&data->lock);
+	sbtsi_mc_to_reg(val, &temp_int, &temp_dec);
+	err = i2c_smbus_write_byte_data(data->client, reg_int, temp_int);
+	if (err)
+		goto exit;
+
+	err = i2c_smbus_write_byte_data(data->client, reg_dec, temp_dec);
+exit:
+	mutex_unlock(&data->lock);
+	return err;
+}
+
+static umode_t sbtsi_is_visible(const void *data,
+				enum hwmon_sensor_types type,
+				u32 attr, int channel)
+{
+	switch (type) {
+	case hwmon_temp:
+		switch (attr) {
+		case hwmon_temp_input:
+			return 0444;
+		case hwmon_temp_min:
+			return 0644;
+		case hwmon_temp_max:
+			return 0644;
+		}
+		break;
+	default:
+		break;
+	}
+	return 0;
+}
+
+static const struct hwmon_channel_info *sbtsi_info[] = {
+	HWMON_CHANNEL_INFO(chip,
+			   HWMON_C_REGISTER_TZ),
+	HWMON_CHANNEL_INFO(temp,
+			   HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX),
+	NULL
+};
+
+static const struct hwmon_ops sbtsi_hwmon_ops = {
+	.is_visible = sbtsi_is_visible,
+	.read = sbtsi_read,
+	.write = sbtsi_write,
+};
+
+static const struct hwmon_chip_info sbtsi_chip_info = {
+	.ops = &sbtsi_hwmon_ops,
+	.info = sbtsi_info,
+};
+
+static int sbtsi_probe(struct i2c_client *client,
+		       const struct i2c_device_id *id)
+{
+	struct device *dev = &client->dev;
+	struct device *hwmon_dev;
+	struct sbtsi_data *data;

drivers/hwmon/sbtsi_temp.c new file +34 -0

+						     &sbtsi_chip_info, NULL);
+
+	return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id sbtsi_id[] = {
+	{"sbtsi", 0},
+	{}
+};
+MODULE_DEVICE_TABLE(i2c, sbtsi_id);
+
+static const struct of_device_id __maybe_unused sbtsi_of_match[] = {
+	{
+		.compatible = "amd,sbtsi",
+	},
+	{ },
+};
+MODULE_DEVICE_TABLE(of, sbtsi_of_match);
+
+static struct i2c_driver sbtsi_driver = {
+	.class = I2C_CLASS_HWMON,
+	.driver = {
+		.name = "sbtsi",
+		.of_match_table = of_match_ptr(sbtsi_of_match),
+	},
+	.probe = sbtsi_probe,
+	.id_table = sbtsi_id,
+};
+
+module_i2c_driver(sbtsi_driver);
+
+MODULE_AUTHOR("Kun Yi <[email protected]>");
+MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor");
+MODULE_LICENSE("GPL");

Signature · 1 line

2.29.2.454.gaff20da3a2-goog

Test status: tested reading temp1_input, and reading/writing temp1_max/min.

SB Temperature Sensor Interface (SB-TSI) is an SMBus compatible interface that reports AMD SoC's Ttcl (normalized temperature), and resembles a typical 8-pin remote temperature sensor's I2C interface to BMC.

This commit adds basic support using this interface to read CPU temperature, and read/write high/low CPU temp thresholds.

To instantiate this driver on an AMD CPU with SB-TSI support, the i2c bus number would be the bus connected from the board management controller (BMC) to the CPU. The i2c address is specified in Section 6.3.1 of the spec [1]: The SB-TSI address is normally 98h for socket 0 and 90h for socket 1, but it could vary based on hardware address select pins.

[1]:
https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.
amd.com%2Fsystem%2Ffiles%2FTechDocs%2F56255_OSRR.pdf&amp;data=04%7C01% 7CNaveenKrishna.Chatradhi%40amd.com%7C1a8cb0ebe4bb43bc759808d8972c562f %7C3dd8961fe4884e608e11a82d994e183d%7C0%7C1%7C637425563976853035%7CUnk nown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWw iLCJXVCI6Mn0%3D%7C1000&amp;sdata=oH5YmE000EUVGVxruzI%2FBRnWOKptlG%2Bpf yKferIwYME%3D&amp;reserved=0

Test status: tested reading temp1_input, and reading/writing temp1_max/min.

Signed-off-by Kun Yi <[email protected]>

---
 drivers/hwmon/Kconfig      |  10 ++
 drivers/hwmon/Makefile     |   1 +
 drivers/hwmon/sbtsi_temp.c | 265 
+++++++++++++++++++++++++++++++++++++
 3 files changed, 276 insertions(+)
 create mode 100644 drivers/hwmon/sbtsi_temp.c

drivers/hwmon/Kconfig index renamed from drivers/hwmon/Kconfig +0 -0

3c059fc23cd6..3d6a809700ae 100644

drivers/hwmon/Kconfig +10 -0

@@ -1522,6 +1522,16 @@ config SENSORS_SL28CPLD
        This driver can also be built as a module.  If so, the module
        will be called sl28cpld-hwmon.
 
+config SENSORS_SBTSI
+     tristate "Emulated SB-TSI temperature sensor"
+     depends on I2C
+     help
+       If you say yes here you get support for emulated temperature
+       sensors on AMD SoCs with SB-TSI interface connected to a BMC device.
+
+       This driver can also be built as a module. If so, the module will
+       be called sbtsi_temp.
+
 config SENSORS_SHT15
      tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
      depends on GPIOLIB || COMPILE_TEST diff --git 

a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile index 01ca5d3fbad4..ee8c037919da 100644

drivers/hwmon/Makefile +1 -0

@@ -160,6 +160,7 @@ obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
 obj-$(CONFIG_SENSORS_PWM_FAN)        += pwm-fan.o
 obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON)      += raspberrypi-hwmon.o
 obj-$(CONFIG_SENSORS_S3C)    += s3c-hwmon.o
+obj-$(CONFIG_SENSORS_SBTSI)  += sbtsi_temp.o
 obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
 obj-$(CONFIG_SENSORS_SCH5627)        += sch5627.o
 obj-$(CONFIG_SENSORS_SCH5636)        += sch5636.o

drivers/hwmon/sbtsi_temp.c new file +71 -0

new file mode 100644 index 000000000000..6b0a7b9df1f3
@@ -0,0 +1,265 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * sbtsi_temp.c - hwmon driver for a SBI Temperature Sensor Interface (SB-TSI)
+ *                compliant AMD SoC temperature device.
+ *
+ * Copyright (c) 2020, Google Inc.
+ * Copyright (c) 2020, Kun Yi <[email protected]>  */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_device.h>
+#include <linux/of.h>
+
+/*
+ * SB-TSI registers only support SMBus byte data access. "_INT" 
+registers are
+ * the integer part of a temperature value or limit, and "_DEC" 
+registers are
+ * corresponding decimal parts.
+ */
+#define SBTSI_REG_TEMP_INT           0x01 /* RO */
+#define SBTSI_REG_STATUS             0x02 /* RO */
+#define SBTSI_REG_CONFIG             0x03 /* RO */
+#define SBTSI_REG_TEMP_HIGH_INT              0x07 /* RW */
+#define SBTSI_REG_TEMP_LOW_INT               0x08 /* RW */
+#define SBTSI_REG_TEMP_DEC           0x10 /* RW */
+#define SBTSI_REG_TEMP_HIGH_DEC              0x13 /* RW */
+#define SBTSI_REG_TEMP_LOW_DEC               0x14 /* RW */
+
+#define SBTSI_CONFIG_READ_ORDER_SHIFT        5
+
+#define SBTSI_TEMP_MIN       0
+#define SBTSI_TEMP_MAX       255875
+
+/* Each client has this additional data */ struct sbtsi_data {
+     struct i2c_client *client;
+     struct mutex lock;
+};
+
+/*
+ * From SB-TSI spec: CPU temperature readings and limit registers 
+encode the
+ * temperature in increments of 0.125 from 0 to 255.875. The "high byte"
+ * register encodes the base-2 of the integer portion, and the upper 
+3 bits of
+ * the "low byte" encode in base-2 the decimal portion.
+ *
+ * e.g. INT=0x19, DEC=0x20 represents 25.125 degrees Celsius
+ *
+ * Therefore temperature in millidegree Celsius =
+ *   (INT + DEC / 256) * 1000 = (INT * 8 + DEC / 32) * 125
+ */
+static inline int sbtsi_reg_to_mc(s32 integer, s32 decimal) {
+     return ((integer << 3) + (decimal >> 5)) * 125; }
+
+/*
+ * Inversely, given temperature in millidegree Celsius
+ *   INT = (TEMP / 125) / 8
+ *   DEC = ((TEMP / 125) % 8) * 32
+ * Caller have to make sure temp doesn't exceed 255875, the max valid value.
+ */
+static inline void sbtsi_mc_to_reg(s32 temp, u8 *integer, u8 
+*decimal) {
+     temp /= 125;
+     *integer = temp >> 3;
+     *decimal = (temp & 0x7) << 5;
+}

drivers/hwmon/sbtsi_temp.c new file +36 -0

+
+     reading_input = false;
+     switch (attr) {
+     case hwmon_temp_input:
+             reading_input = true;
+             /*
+              * ReadOrder bit specifies the reading order of integer and
+              * decimal part of CPU temp for atomic reads. If bit == 0,
+              * reading integer part triggers latching of the decimal part,
+              * so integer part should be read first. If bit == 1, read
+              * order should be reversed.
+              */
+             err = i2c_smbus_read_byte_data(data->client, SBTSI_REG_CONFIG);
+             if (err < 0)
+                     return err;
+
+             mutex_lock(&data->lock);
+             if (err & BIT(SBTSI_CONFIG_READ_ORDER_SHIFT)) {
+                     temp_dec = i2c_smbus_read_byte_data(data->client,
+                                                         SBTSI_REG_TEMP_DEC);
+                     temp_int = i2c_smbus_read_byte_data(data->client,
+                                                         SBTSI_REG_TEMP_INT);
+             } else {
+                     temp_int = i2c_smbus_read_byte_data(data->client,
+                                                         SBTSI_REG_TEMP_INT);
+                     temp_dec = i2c_smbus_read_byte_data(data->client,
+                                                         SBTSI_REG_TEMP_DEC);
+             }
+             mutex_unlock(&data->lock);
+             break;
+     case hwmon_temp_max:
+             reg_int = SBTSI_REG_TEMP_HIGH_INT;
+             reg_dec = SBTSI_REG_TEMP_HIGH_DEC;
+             break;
+     case hwmon_temp_min:
+             reg_int = SBTSI_REG_TEMP_LOW_INT;

drivers/hwmon/sbtsi_temp.c new file +9 -0

+
+     if (temp_int < 0)
+             return temp_int;
+     if (temp_dec < 0)
+             return temp_dec;
+
+     *val = sbtsi_reg_to_mc(temp_int, temp_dec);
+
+     return 0;

drivers/hwmon/sbtsi_temp.c new file +73 -0

+
+     switch (attr) {
+     case hwmon_temp_max:
+             reg_int = SBTSI_REG_TEMP_HIGH_INT;
+             reg_dec = SBTSI_REG_TEMP_HIGH_DEC;
+             break;
+     case hwmon_temp_min:
+             reg_int = SBTSI_REG_TEMP_LOW_INT;
+             reg_dec = SBTSI_REG_TEMP_LOW_DEC;
+             break;
+     default:
+             return -EINVAL;
+     }
+
+     val = clamp_val(val, SBTSI_TEMP_MIN, SBTSI_TEMP_MAX);
+     mutex_lock(&data->lock);
+     sbtsi_mc_to_reg(val, &temp_int, &temp_dec);
+     err = i2c_smbus_write_byte_data(data->client, reg_int, temp_int);
+     if (err)
+             goto exit;
+
+     err = i2c_smbus_write_byte_data(data->client, reg_dec, 
+temp_dec);
+exit:
+     mutex_unlock(&data->lock);
+     return err;
+}
+
+static umode_t sbtsi_is_visible(const void *data,
+                             enum hwmon_sensor_types type,
+                             u32 attr, int channel) {
+     switch (type) {
+     case hwmon_temp:
+             switch (attr) {
+             case hwmon_temp_input:
+                     return 0444;
+             case hwmon_temp_min:
+                     return 0644;
+             case hwmon_temp_max:
+                     return 0644;
+             }
+             break;
+     default:
+             break;
+     }
+     return 0;
+}
+
+static const struct hwmon_channel_info *sbtsi_info[] = {
+     HWMON_CHANNEL_INFO(chip,
+                        HWMON_C_REGISTER_TZ),
+     HWMON_CHANNEL_INFO(temp,
+                        HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX),
+     NULL
+};
+
+static const struct hwmon_ops sbtsi_hwmon_ops = {
+     .is_visible = sbtsi_is_visible,
+     .read = sbtsi_read,
+     .write = sbtsi_write,
+};
+
+static const struct hwmon_chip_info sbtsi_chip_info = {
+     .ops = &sbtsi_hwmon_ops,
+     .info = sbtsi_info,
+};
+
+static int sbtsi_probe(struct i2c_client *client,
+                    const struct i2c_device_id *id) {
+     struct device *dev = &client->dev;
+     struct device *hwmon_dev;
+     struct sbtsi_data *data;
+

drivers/hwmon/sbtsi_temp.c new file +33 -1

+                                                  &sbtsi_chip_info, 
+ NULL);
+
+     return PTR_ERR_OR_ZERO(hwmon_dev); }
+
+static const struct i2c_device_id sbtsi_id[] = {
+     {"sbtsi", 0},
+     {}
+};
+MODULE_DEVICE_TABLE(i2c, sbtsi_id);
+
+static const struct of_device_id __maybe_unused sbtsi_of_match[] = {
+     {
+             .compatible = "amd,sbtsi",
+     },
+     { },
+};
+MODULE_DEVICE_TABLE(of, sbtsi_of_match);
+
+static struct i2c_driver sbtsi_driver = {
+     .class = I2C_CLASS_HWMON,
+     .driver = {
+             .name = "sbtsi",
+             .of_match_table = of_match_ptr(sbtsi_of_match),
+     },
+     .probe = sbtsi_probe,
+     .id_table = sbtsi_id,
+};
+
+module_i2c_driver(sbtsi_driver);
+
+MODULE_AUTHOR("Kun Yi <[email protected]>"); MODULE_DESCRIPTION("Hwmon 
+driver for AMD SB-TSI emulated sensor"); MODULE_LICENSE("GPL");
--

2.29.2.454.gaff20da3a2-goog

Quoted 143 lines · Kun Yi

SB Temperature Sensor Interface (SB-TSI) is an SMBus compatible interface that reports AMD SoC's Ttcl (normalized temperature), and resembles a typical 8-pin remote temperature sensor's I2C interface to BMC.

This commit adds basic support using this interface to read CPU temperature, and read/write high/low CPU temp thresholds.

To instantiate this driver on an AMD CPU with SB-TSI
support, the i2c bus number would be the bus connected from the board management controller (BMC) to the CPU. The i2c address is specified in Section 6.3.1 of the spec [1]: The SB-TSI address is normally 98h for socket 0 and 90h for socket 1, but it could vary based on hardware address select pins.

[1]: https://www.amd.com/system/files/TechDocs/56255_OSRR.pdf

Test status: tested reading temp1_input, and reading/writing temp1_max/min.

Signed-off-by Kun Yi <[email protected]>

---
 drivers/hwmon/Kconfig      |  10 ++
 drivers/hwmon/Makefile     |   1 +
 drivers/hwmon/sbtsi_temp.c | 265 +++++++++++++++++++++++++++++++++++++
 3 files changed, 276 insertions(+)
 create mode 100644 drivers/hwmon/sbtsi_temp.c

drivers/hwmon/Kconfig +10 -0

index 3c059fc23cd6..3d6a809700ae 100644
@@ -1522,6 +1522,16 @@ config SENSORS_SL28CPLD
        This driver can also be built as a module.  If so, the module
        will be called sl28cpld-hwmon.
 
+config SENSORS_SBTSI
+     tristate "Emulated SB-TSI temperature sensor"
+     depends on I2C
+     help
+       If you say yes here you get support for emulated temperature
+       sensors on AMD SoCs with SB-TSI interface connected to a BMC device.
+
+       This driver can also be built as a module. If so, the module will
+       be called sbtsi_temp.
+
 config SENSORS_SHT15
      tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
      depends on GPIOLIB || COMPILE_TEST

drivers/hwmon/Makefile +1 -0

index 01ca5d3fbad4..ee8c037919da 100644
@@ -160,6 +160,7 @@ obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
 obj-$(CONFIG_SENSORS_PWM_FAN)        += pwm-fan.o
 obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON)      += raspberrypi-hwmon.o
 obj-$(CONFIG_SENSORS_S3C)    += s3c-hwmon.o
+obj-$(CONFIG_SENSORS_SBTSI)  += sbtsi_temp.o
 obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
 obj-$(CONFIG_SENSORS_SCH5627)        += sch5627.o
 obj-$(CONFIG_SENSORS_SCH5636)        += sch5636.o

drivers/hwmon/sbtsi_temp.c new file +76 -0

new file mode 100644
index 000000000000..6b0a7b9df1f3
@@ -0,0 +1,265 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * sbtsi_temp.c - hwmon driver for a SBI Temperature Sensor Interface (SB-TSI)
+ *                compliant AMD SoC temperature device.
+ *
+ * Copyright (c) 2020, Google Inc.
+ * Copyright (c) 2020, Kun Yi <[email protected]>
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_device.h>
+#include <linux/of.h>
+
+/*
+ * SB-TSI registers only support SMBus byte data access. "_INT" registers are
+ * the integer part of a temperature value or limit, and "_DEC" registers are
+ * corresponding decimal parts.
+ */
+#define SBTSI_REG_TEMP_INT           0x01 /* RO */
+#define SBTSI_REG_STATUS             0x02 /* RO */
+#define SBTSI_REG_CONFIG             0x03 /* RO */
+#define SBTSI_REG_TEMP_HIGH_INT              0x07 /* RW */
+#define SBTSI_REG_TEMP_LOW_INT               0x08 /* RW */
+#define SBTSI_REG_TEMP_DEC           0x10 /* RW */
+#define SBTSI_REG_TEMP_HIGH_DEC              0x13 /* RW */
+#define SBTSI_REG_TEMP_LOW_DEC               0x14 /* RW */
+
+#define SBTSI_CONFIG_READ_ORDER_SHIFT        5
+
+#define SBTSI_TEMP_MIN       0
+#define SBTSI_TEMP_MAX       255875
+
+/* Each client has this additional data */
+struct sbtsi_data {
+     struct i2c_client *client;
+     struct mutex lock;
+};
+
+/*
+ * From SB-TSI spec: CPU temperature readings and limit registers encode the
+ * temperature in increments of 0.125 from 0 to 255.875. The "high byte"
+ * register encodes the base-2 of the integer portion, and the upper 3 bits of
+ * the "low byte" encode in base-2 the decimal portion.
+ *
+ * e.g. INT=0x19, DEC=0x20 represents 25.125 degrees Celsius
+ *
+ * Therefore temperature in millidegree Celsius =
+ *   (INT + DEC / 256) * 1000 = (INT * 8 + DEC / 32) * 125
+ */
+static inline int sbtsi_reg_to_mc(s32 integer, s32 decimal)
+{
+     return ((integer << 3) + (decimal >> 5)) * 125;
+}
+
+/*
+ * Inversely, given temperature in millidegree Celsius
+ *   INT = (TEMP / 125) / 8
+ *   DEC = ((TEMP / 125) % 8) * 32
+ * Caller have to make sure temp doesn't exceed 255875, the max valid value.
+ */
+static inline void sbtsi_mc_to_reg(s32 temp, u8 *integer, u8 *decimal)
+{
+     temp /= 125;
+     *integer = temp >> 3;
+     *decimal = (temp & 0x7) << 5;
+}
+
+static int sbtsi_read(struct device *dev, enum hwmon_sensor_types type,
+                   u32 attr, int channel, long *val)
+{
+     struct sbtsi_data *data = dev_get_drvdata(dev);

drivers/hwmon/sbtsi_temp.c line 82

Quoted 6 lines

drivers/hwmon/sbtsi_temp.c new file +6 -0

+     s32 temp_int, temp_dec;
+     int err, reg_int, reg_dec;
+     bool reading_input;
+
+     if (type != hwmon_temp)
+             return -EINVAL;

Unnecessary check.

Quoted 43 lines

drivers/hwmon/sbtsi_temp.c new file +42 -0

+
+     reading_input = false;
+     switch (attr) {
+     case hwmon_temp_input:
+             reading_input = true;
+             /*
+              * ReadOrder bit specifies the reading order of integer and
+              * decimal part of CPU temp for atomic reads. If bit == 0,
+              * reading integer part triggers latching of the decimal part,
+              * so integer part should be read first. If bit == 1, read
+              * order should be reversed.
+              */
+             err = i2c_smbus_read_byte_data(data->client, SBTSI_REG_CONFIG);
+             if (err < 0)
+                     return err;
+
+             mutex_lock(&data->lock);
+             if (err & BIT(SBTSI_CONFIG_READ_ORDER_SHIFT)) {
+                     temp_dec = i2c_smbus_read_byte_data(data->client,
+                                                         SBTSI_REG_TEMP_DEC);
+                     temp_int = i2c_smbus_read_byte_data(data->client,
+                                                         SBTSI_REG_TEMP_INT);
+             } else {
+                     temp_int = i2c_smbus_read_byte_data(data->client,
+                                                         SBTSI_REG_TEMP_INT);
+                     temp_dec = i2c_smbus_read_byte_data(data->client,
+                                                         SBTSI_REG_TEMP_DEC);
+             }
+             mutex_unlock(&data->lock);
+             break;
+     case hwmon_temp_max:
+             reg_int = SBTSI_REG_TEMP_HIGH_INT;
+             reg_dec = SBTSI_REG_TEMP_HIGH_DEC;
+             break;
+     case hwmon_temp_min:
+             reg_int = SBTSI_REG_TEMP_LOW_INT;
+             reg_dec = SBTSI_REG_TEMP_LOW_DEC;
+             break;
+     default:
+             return -EINVAL;
+     }
+

drivers/hwmon/sbtsi_temp.c line 128

Quoted 4 lines

drivers/hwmon/sbtsi_temp.c new file +4 -0

+     if (!reading_input) {
+             temp_int = i2c_smbus_read_byte_data(data->client, reg_int);
+             temp_dec = i2c_smbus_read_byte_data(data->client, reg_dec);
+     }

This adds unnecessary complexity. I would suggest to move the calls to the case statements and drop reading_input as well as reg_int, reg_dec.

Also, I just realized that the mutex is needed here as well, since the values might be written while being read, which could result in inconsistent read values. Example: Limit is changed from 100 to 99.75. Since the integer value is written first, it is possible that 99.0 is returned.

Quoted 15 lines

drivers/hwmon/sbtsi_temp.c new file +14 -0

+
+     if (temp_int < 0)
+             return temp_int;
+     if (temp_dec < 0)
+             return temp_dec;
+
+     *val = sbtsi_reg_to_mc(temp_int, temp_dec);
+
+     return 0;
+}
+
+static int sbtsi_write(struct device *dev, enum hwmon_sensor_types type,
+                    u32 attr, int channel, long val)
+{

drivers/hwmon/sbtsi_temp.c line 148

Quoted 6 lines

drivers/hwmon/sbtsi_temp.c new file +6 -0

+     struct sbtsi_data *data = dev_get_drvdata(dev);
+     int reg_int, reg_dec, err;
+     u8 temp_int, temp_dec;
+
+     if (type != hwmon_temp)
+             return -EINVAL;

This check is really unnecessary.

Quoted 78 lines

drivers/hwmon/sbtsi_temp.c new file +77 -0

+
+     switch (attr) {
+     case hwmon_temp_max:
+             reg_int = SBTSI_REG_TEMP_HIGH_INT;
+             reg_dec = SBTSI_REG_TEMP_HIGH_DEC;
+             break;
+     case hwmon_temp_min:
+             reg_int = SBTSI_REG_TEMP_LOW_INT;
+             reg_dec = SBTSI_REG_TEMP_LOW_DEC;
+             break;
+     default:
+             return -EINVAL;
+     }
+
+     val = clamp_val(val, SBTSI_TEMP_MIN, SBTSI_TEMP_MAX);
+     mutex_lock(&data->lock);
+     sbtsi_mc_to_reg(val, &temp_int, &temp_dec);
+     err = i2c_smbus_write_byte_data(data->client, reg_int, temp_int);
+     if (err)
+             goto exit;
+
+     err = i2c_smbus_write_byte_data(data->client, reg_dec, temp_dec);
+exit:
+     mutex_unlock(&data->lock);
+     return err;
+}
+
+static umode_t sbtsi_is_visible(const void *data,
+                             enum hwmon_sensor_types type,
+                             u32 attr, int channel)
+{
+     switch (type) {
+     case hwmon_temp:
+             switch (attr) {
+             case hwmon_temp_input:
+                     return 0444;
+             case hwmon_temp_min:
+                     return 0644;
+             case hwmon_temp_max:
+                     return 0644;
+             }
+             break;
+     default:
+             break;
+     }
+     return 0;
+}
+
+static const struct hwmon_channel_info *sbtsi_info[] = {
+     HWMON_CHANNEL_INFO(chip,
+                        HWMON_C_REGISTER_TZ),
+     HWMON_CHANNEL_INFO(temp,
+                        HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX),
+     NULL
+};
+
+static const struct hwmon_ops sbtsi_hwmon_ops = {
+     .is_visible = sbtsi_is_visible,
+     .read = sbtsi_read,
+     .write = sbtsi_write,
+};
+
+static const struct hwmon_chip_info sbtsi_chip_info = {
+     .ops = &sbtsi_hwmon_ops,
+     .info = sbtsi_info,
+};
+
+static int sbtsi_probe(struct i2c_client *client,
+                    const struct i2c_device_id *id)
+{
+     struct device *dev = &client->dev;
+     struct device *hwmon_dev;
+     struct sbtsi_data *data;
+
+     data = devm_kzalloc(dev, sizeof(struct sbtsi_data), GFP_KERNEL);
+     if (!data)
+             return -ENOMEM;

drivers/hwmon/sbtsi_temp.c line 231

Quoted 6 lines

drivers/hwmon/sbtsi_temp.c new file +6 -0

+
+     data->client = client;
+     mutex_init(&data->lock);
+
+     hwmon_dev =
+             devm_hwmon_device_register_with_info(dev, client->name, data,

Line length limit is now 100 columns, so the above line split is unnecessary.

Quoted 38 lines

drivers/hwmon/sbtsi_temp.c new file +34 -1

+                                                  &sbtsi_chip_info, NULL);
+
+     return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id sbtsi_id[] = {
+     {"sbtsi", 0},
+     {}
+};
+MODULE_DEVICE_TABLE(i2c, sbtsi_id);
+
+static const struct of_device_id __maybe_unused sbtsi_of_match[] = {
+     {
+             .compatible = "amd,sbtsi",
+     },
+     { },
+};
+MODULE_DEVICE_TABLE(of, sbtsi_of_match);
+
+static struct i2c_driver sbtsi_driver = {
+     .class = I2C_CLASS_HWMON,
+     .driver = {
+             .name = "sbtsi",
+             .of_match_table = of_match_ptr(sbtsi_of_match),
+     },
+     .probe = sbtsi_probe,
+     .id_table = sbtsi_id,
+};
+
+module_i2c_driver(sbtsi_driver);
+
+MODULE_AUTHOR("Kun Yi <[email protected]>");
+MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor");
+MODULE_LICENSE("GPL");
--

2.29.2.454.gaff20da3a2-goog

[CAUTION: External Email]

SB Temperature Sensor Interface (SB-TSI) is an SMBus compatible interface that reports AMD SoC's Ttcl (normalized temperature), and resembles a typical 8-pin remote temperature sensor's I2C interface to BMC.

This commit adds basic support using this interface to read CPU temperature, and read/write high/low CPU temp thresholds.

To instantiate this driver on an AMD CPU with SB-TSI
support, the i2c bus number would be the bus connected from the board management controller (BMC) to the CPU. The i2c address is specified in Section 6.3.1 of the spec [1]: The SB-TSI address is normally 98h for socket 0 and 90h for socket 1, but it could vary based on hardware address select pins.

[1]: https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fwww.amd.com%2Fsystem%2Ffiles%2FTechDocs%2F56255_OSRR.pdf&amp;data=04%7C01%7Csupreeth.venkatesh%40amd.com%7C412ca045665445483a0a08d896e33084%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C1%7C637425250268541698%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&amp;sdata=Xir5Jg%2FgHz8isnXNkmZMTRjg%2FOht%2FSDR4gajR5wVgSU%3D&amp;reserved=0

Test status: tested reading temp1_input, and reading/writing temp1_max/min.

Signed-off-by Kun Yi <[email protected]>

---
 drivers/hwmon/Kconfig      |  10 ++
 drivers/hwmon/Makefile     |   1 +
 drivers/hwmon/sbtsi_temp.c | 265 +++++++++++++++++++++++++++++++++++++
 3 files changed, 276 insertions(+)
 create mode 100644 drivers/hwmon/sbtsi_temp.c

drivers/hwmon/Kconfig +10 -0

index 3c059fc23cd6..3d6a809700ae 100644
@@ -1522,6 +1522,16 @@ config SENSORS_SL28CPLD
          This driver can also be built as a module.  If so, the module
          will be called sl28cpld-hwmon.
 
+config SENSORS_SBTSI
+       tristate "Emulated SB-TSI temperature sensor"
+       depends on I2C
+       help
+         If you say yes here you get support for emulated temperature
+         sensors on AMD SoCs with SB-TSI interface connected to a BMC device.
+
+         This driver can also be built as a module. If so, the module will
+         be called sbtsi_temp.
+
 config SENSORS_SHT15
        tristate "Sensiron humidity and temperature sensors. SHT15 and compat."
        depends on GPIOLIB || COMPILE_TEST

drivers/hwmon/Makefile +1 -0

index 01ca5d3fbad4..ee8c037919da 100644
@@ -160,6 +160,7 @@ obj-$(CONFIG_SENSORS_POWR1220)  += powr1220.o
 obj-$(CONFIG_SENSORS_PWM_FAN)  += pwm-fan.o
 obj-$(CONFIG_SENSORS_RASPBERRYPI_HWMON)        += raspberrypi-hwmon.o
 obj-$(CONFIG_SENSORS_S3C)      += s3c-hwmon.o
+obj-$(CONFIG_SENSORS_SBTSI)    += sbtsi_temp.o
 obj-$(CONFIG_SENSORS_SCH56XX_COMMON)+= sch56xx-common.o
 obj-$(CONFIG_SENSORS_SCH5627)  += sch5627.o
 obj-$(CONFIG_SENSORS_SCH5636)  += sch5636.o

drivers/hwmon/sbtsi_temp.c new file +265 -1

new file mode 100644
index 000000000000..6b0a7b9df1f3
@@ -0,0 +1,265 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * sbtsi_temp.c - hwmon driver for a SBI Temperature Sensor Interface (SB-TSI)
+ *                compliant AMD SoC temperature device.
+ *
+ * Copyright (c) 2020, Google Inc.
+ * Copyright (c) 2020, Kun Yi <[email protected]>
+ */
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/hwmon.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/of_device.h>
+#include <linux/of.h>
+
+/*
+ * SB-TSI registers only support SMBus byte data access. "_INT" registers are
+ * the integer part of a temperature value or limit, and "_DEC" registers are
+ * corresponding decimal parts.
+ */
+#define SBTSI_REG_TEMP_INT             0x01 /* RO */
+#define SBTSI_REG_STATUS               0x02 /* RO */
+#define SBTSI_REG_CONFIG               0x03 /* RO */
+#define SBTSI_REG_TEMP_HIGH_INT                0x07 /* RW */
+#define SBTSI_REG_TEMP_LOW_INT         0x08 /* RW */
+#define SBTSI_REG_TEMP_DEC             0x10 /* RW */
+#define SBTSI_REG_TEMP_HIGH_DEC                0x13 /* RW */
+#define SBTSI_REG_TEMP_LOW_DEC         0x14 /* RW */
+
+#define SBTSI_CONFIG_READ_ORDER_SHIFT  5
+
+#define SBTSI_TEMP_MIN 0
+#define SBTSI_TEMP_MAX 255875
+
+/* Each client has this additional data */
+struct sbtsi_data {
+       struct i2c_client *client;
+       struct mutex lock;
+};
+
+/*
+ * From SB-TSI spec: CPU temperature readings and limit registers encode the
+ * temperature in increments of 0.125 from 0 to 255.875. The "high byte"
+ * register encodes the base-2 of the integer portion, and the upper 3 bits of
+ * the "low byte" encode in base-2 the decimal portion.
+ *
+ * e.g. INT=0x19, DEC=0x20 represents 25.125 degrees Celsius
+ *
+ * Therefore temperature in millidegree Celsius =
+ *   (INT + DEC / 256) * 1000 = (INT * 8 + DEC / 32) * 125
+ */
+static inline int sbtsi_reg_to_mc(s32 integer, s32 decimal)
+{
+       return ((integer << 3) + (decimal >> 5)) * 125;
+}
+
+/*
+ * Inversely, given temperature in millidegree Celsius
+ *   INT = (TEMP / 125) / 8
+ *   DEC = ((TEMP / 125) % 8) * 32
+ * Caller have to make sure temp doesn't exceed 255875, the max valid value.
+ */
+static inline void sbtsi_mc_to_reg(s32 temp, u8 *integer, u8 *decimal)
+{
+       temp /= 125;
+       *integer = temp >> 3;
+       *decimal = (temp & 0x7) << 5;
+}
+
+static int sbtsi_read(struct device *dev, enum hwmon_sensor_types type,
+                     u32 attr, int channel, long *val)
+{
+       struct sbtsi_data *data = dev_get_drvdata(dev);
+       s32 temp_int, temp_dec;
+       int err, reg_int, reg_dec;
+       bool reading_input;
+
+       if (type != hwmon_temp)
+               return -EINVAL;
+
+       reading_input = false;
+       switch (attr) {
+       case hwmon_temp_input:
+               reading_input = true;
+               /*
+                * ReadOrder bit specifies the reading order of integer and
+                * decimal part of CPU temp for atomic reads. If bit == 0,
+                * reading integer part triggers latching of the decimal part,
+                * so integer part should be read first. If bit == 1, read
+                * order should be reversed.
+                */
+               err = i2c_smbus_read_byte_data(data->client, SBTSI_REG_CONFIG);
+               if (err < 0)
+                       return err;
+
+               mutex_lock(&data->lock);
+               if (err & BIT(SBTSI_CONFIG_READ_ORDER_SHIFT)) {
+                       temp_dec = i2c_smbus_read_byte_data(data->client,
+                                                           SBTSI_REG_TEMP_DEC);
+                       temp_int = i2c_smbus_read_byte_data(data->client,
+                                                           SBTSI_REG_TEMP_INT);
+               } else {
+                       temp_int = i2c_smbus_read_byte_data(data->client,
+                                                           SBTSI_REG_TEMP_INT);
+                       temp_dec = i2c_smbus_read_byte_data(data->client,
+                                                           SBTSI_REG_TEMP_DEC);
+               }
+               mutex_unlock(&data->lock);
+               break;
+       case hwmon_temp_max:
+               reg_int = SBTSI_REG_TEMP_HIGH_INT;
+               reg_dec = SBTSI_REG_TEMP_HIGH_DEC;
+               break;
+       case hwmon_temp_min:
+               reg_int = SBTSI_REG_TEMP_LOW_INT;
+               reg_dec = SBTSI_REG_TEMP_LOW_DEC;
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       if (!reading_input) {
+               temp_int = i2c_smbus_read_byte_data(data->client, reg_int);
+               temp_dec = i2c_smbus_read_byte_data(data->client, reg_dec);
+       }
+
+       if (temp_int < 0)
+               return temp_int;
+       if (temp_dec < 0)
+               return temp_dec;
+
+       *val = sbtsi_reg_to_mc(temp_int, temp_dec);
+
+       return 0;
+}
+
+static int sbtsi_write(struct device *dev, enum hwmon_sensor_types type,
+                      u32 attr, int channel, long val)
+{
+       struct sbtsi_data *data = dev_get_drvdata(dev);
+       int reg_int, reg_dec, err;
+       u8 temp_int, temp_dec;
+
+       if (type != hwmon_temp)
+               return -EINVAL;
+
+       switch (attr) {
+       case hwmon_temp_max:
+               reg_int = SBTSI_REG_TEMP_HIGH_INT;
+               reg_dec = SBTSI_REG_TEMP_HIGH_DEC;
+               break;
+       case hwmon_temp_min:
+               reg_int = SBTSI_REG_TEMP_LOW_INT;
+               reg_dec = SBTSI_REG_TEMP_LOW_DEC;
+               break;
+       default:
+               return -EINVAL;
+       }
+
+       val = clamp_val(val, SBTSI_TEMP_MIN, SBTSI_TEMP_MAX);
+       mutex_lock(&data->lock);
+       sbtsi_mc_to_reg(val, &temp_int, &temp_dec);
+       err = i2c_smbus_write_byte_data(data->client, reg_int, temp_int);
+       if (err)
+               goto exit;
+
+       err = i2c_smbus_write_byte_data(data->client, reg_dec, temp_dec);
+exit:
+       mutex_unlock(&data->lock);
+       return err;
+}
+
+static umode_t sbtsi_is_visible(const void *data,
+                               enum hwmon_sensor_types type,
+                               u32 attr, int channel)
+{
+       switch (type) {
+       case hwmon_temp:
+               switch (attr) {
+               case hwmon_temp_input:
+                       return 0444;
+               case hwmon_temp_min:
+                       return 0644;
+               case hwmon_temp_max:
+                       return 0644;
+               }
+               break;
+       default:
+               break;
+       }
+       return 0;
+}
+
+static const struct hwmon_channel_info *sbtsi_info[] = {
+       HWMON_CHANNEL_INFO(chip,
+                          HWMON_C_REGISTER_TZ),
+       HWMON_CHANNEL_INFO(temp,
+                          HWMON_T_INPUT | HWMON_T_MIN | HWMON_T_MAX),
+       NULL
+};
+
+static const struct hwmon_ops sbtsi_hwmon_ops = {
+       .is_visible = sbtsi_is_visible,
+       .read = sbtsi_read,
+       .write = sbtsi_write,
+};
+
+static const struct hwmon_chip_info sbtsi_chip_info = {
+       .ops = &sbtsi_hwmon_ops,
+       .info = sbtsi_info,
+};
+
+static int sbtsi_probe(struct i2c_client *client,
+                      const struct i2c_device_id *id)
+{
+       struct device *dev = &client->dev;
+       struct device *hwmon_dev;
+       struct sbtsi_data *data;
+
+       data = devm_kzalloc(dev, sizeof(struct sbtsi_data), GFP_KERNEL);
+       if (!data)
+               return -ENOMEM;
+
+       data->client = client;
+       mutex_init(&data->lock);
+
+       hwmon_dev =
+               devm_hwmon_device_register_with_info(dev, client->name, data,
+                                                    &sbtsi_chip_info, NULL);
+
+       return PTR_ERR_OR_ZERO(hwmon_dev);
+}
+
+static const struct i2c_device_id sbtsi_id[] = {
+       {"sbtsi", 0},
+       {}
+};
+MODULE_DEVICE_TABLE(i2c, sbtsi_id);
+
+static const struct of_device_id __maybe_unused sbtsi_of_match[] = {
+       {
+               .compatible = "amd,sbtsi",
+       },
+       { },
+};
+MODULE_DEVICE_TABLE(of, sbtsi_of_match);
+
+static struct i2c_driver sbtsi_driver = {
+       .class = I2C_CLASS_HWMON,
+       .driver = {
+               .name = "sbtsi",
+               .of_match_table = of_match_ptr(sbtsi_of_match),
+       },
+       .probe = sbtsi_probe,
+       .id_table = sbtsi_id,
+};
+
+module_i2c_driver(sbtsi_driver);
+
+MODULE_AUTHOR("Kun Yi <[email protected]>");
+MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor");
+MODULE_LICENSE("GPL");
--

2.29.2.454.gaff20da3a2-goog

Document device tree bindings for AMD SB-TSI emulated temperature sensor.

Signed-off-by Kun Yi <[email protected]>

---
 .../devicetree/bindings/hwmon/amd,sbtsi.yaml  | 54 +++++++++++++++++++
 1 file changed, 54 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/hwmon/amd,sbtsi.yaml