[PATCH v1 3/6] misc: amd-sbi: Split SBTSI hwmon sensor handling into a separate entity

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

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

Separate SBTSI hwmon sensor handling from the core path to improve
code organization and maintainability.

This keeps core transport/register access independent while preserving
existing hwmon functionality through a dedicated hwmon component.

Reviewed-by: Akshay Gupta <Akshay.Gupta@amd.com>
Signed-off-by: Prathima <Prathima.Lk@amd.com>
---
 drivers/misc/amd-sbi/Kconfig                  |  12 +-
 drivers/misc/amd-sbi/Makefile                 |   2 +
 drivers/misc/amd-sbi/tsi-core.h               |  30 +++++
 drivers/misc/amd-sbi/{sbtsi.c => tsi-hwmon.c} | 120 ++++--------------
 drivers/misc/amd-sbi/tsi.c                    |  77 +++++++++++
 5 files changed, 142 insertions(+), 99 deletions(-)
 create mode 100644 drivers/misc/amd-sbi/tsi-core.h
 rename drivers/misc/amd-sbi/{sbtsi.c => tsi-hwmon.c} (57%)
 create mode 100644 drivers/misc/amd-sbi/tsi.c

diff --git a/drivers/misc/amd-sbi/Kconfig b/drivers/misc/amd-sbi/Kconfig
index 19a8d596e8f5..2710860a86c7 100644
--- a/drivers/misc/amd-sbi/Kconfig
+++ b/drivers/misc/amd-sbi/Kconfig
@@ -25,7 +25,6 @@ config SENSORS_SBTSI
 	tristate "Emulated SB-TSI temperature sensor"
 	depends on I2C
 	depends on ARM || ARM64 || COMPILE_TEST
-	depends on HWMON
 	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.
@@ -33,3 +32,14 @@ config SENSORS_SBTSI
 
 	  This driver can also be built as a module. If so, the module will
 	  be called sbtsi.
+
+config AMD_SBTSI_HWMON
+	bool "SBTSI hardware monitoring for AMD platforms"
+	depends on SENSORS_SBTSI && HWMON
+	depends on !(SENSORS_SBTSI=y && HWMON=m)
+	default y
+	help
+	  This provides support for TSI device hardware monitoring.
+	  When enabled, a hwmon device is created for each socket to expose
+	  temperature monitoring data through the standard Linux
+	  hwmon interface.
diff --git a/drivers/misc/amd-sbi/Makefile b/drivers/misc/amd-sbi/Makefile
index f04273c0d3ad..a874136e438f 100644
--- a/drivers/misc/amd-sbi/Makefile
+++ b/drivers/misc/amd-sbi/Makefile
@@ -3,4 +3,6 @@ sbrmi-i2c-objs  		+= rmi-i2c.o rmi-core.o
 sbrmi-i2c-$(CONFIG_AMD_SBRMI_HWMON)	+= rmi-hwmon.o
 obj-$(CONFIG_AMD_SBRMI_I2C)	+= sbrmi-i2c.o
 # SBTSI Configuration
+sbtsi-objs	+= tsi.o
+sbtsi-$(CONFIG_AMD_SBTSI_HWMON)	+= tsi-hwmon.o
 obj-$(CONFIG_SENSORS_SBTSI)	+= sbtsi.o
diff --git a/drivers/misc/amd-sbi/tsi-core.h b/drivers/misc/amd-sbi/tsi-core.h
new file mode 100644
index 000000000000..e60cf25fda7a
--- /dev/null
+++ b/drivers/misc/amd-sbi/tsi-core.h
@@ -0,0 +1,30 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * Copyright (C) 2026 Advanced Micro Devices, Inc.
+ */
+
+#ifndef _TSI_CORE_H_
+#define _TSI_CORE_H_
+
+#include <linux/err.h>
+#include <linux/i2c.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/of.h>
+
+/* Each client has this additional data */
+struct sbtsi_data {
+	struct i2c_client *client;
+	bool ext_range_mode;
+	bool read_order;
+};
+
+#ifdef CONFIG_AMD_SBTSI_HWMON
+int create_sbtsi_hwmon_sensor_device(struct device *dev, struct sbtsi_data *data);
+#else
+static inline int create_sbtsi_hwmon_sensor_device(struct device *dev, struct sbtsi_data *data)
+{
+	return 0;
+}
+#endif
+#endif /*_TSI_CORE_H_*/
diff --git a/drivers/misc/amd-sbi/sbtsi.c b/drivers/misc/amd-sbi/tsi-hwmon.c
similarity index 57%
rename from drivers/misc/amd-sbi/sbtsi.c
rename to drivers/misc/amd-sbi/tsi-hwmon.c
index e09b10c17771..efd450a85d34 100644
--- a/drivers/misc/amd-sbi/sbtsi.c
+++ b/drivers/misc/amd-sbi/tsi-hwmon.c
@@ -1,59 +1,31 @@
 // SPDX-License-Identifier: GPL-2.0-or-later
 /*
- * sbtsi.c - hwmon driver for a SBI Temperature Sensor Interface (SB-TSI)
- *                compliant AMD SoC temperature device.
+ * tsi-hwmon.c - hwmon sensor support for side band TSI
  *
  * Copyright (c) 2020, Google Inc.
  * Copyright (c) 2020, Kun Yi <kunyi@google.com>
  */
 
-#include <linux/err.h>
-#include <linux/i2c.h>
-#include <linux/init.h>
 #include <linux/hwmon.h>
-#include <linux/module.h>
-#include <linux/of.h>
-#include <linux/bitfield.h>
+#include "tsi-core.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_REG_TEMP_INT             0x01 /* RO */
+#define SBTSI_REG_STATUS               0x02 /* 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 */
 
-/*
- * Bit for reporting value with temperature measurement range.
- * bit == 0: Use default temperature range (0C to 255.875C).
- * bit == 1: Use extended temperature range (-49C to +206.875C).
- */
-#define SBTSI_CONFIG_EXT_RANGE_SHIFT	2
-/*
- * ReadOrder bit specifies the reading order of integer and decimal part of
- * CPU temperature 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.
- */
-#define SBTSI_CONFIG_READ_ORDER_SHIFT	5
-
-#define SBTSI_TEMP_EXT_RANGE_ADJ	49000
-
-#define SBTSI_TEMP_MIN	0
-#define SBTSI_TEMP_MAX	255875
+#define SBTSI_TEMP_EXT_RANGE_ADJ       49000
 
-/* Each client has this additional data */
-struct sbtsi_data {
-	struct i2c_client *client;
-	bool ext_range_mode;
-	bool read_order;
-};
+#define SBTSI_TEMP_MIN 0
+#define SBTSI_TEMP_MAX 255875
 
 /*
  * From SB-TSI spec: CPU temperature readings and limit registers encode the
@@ -85,7 +57,7 @@ static inline void sbtsi_mc_to_reg(s32 temp, u8 *integer, u8 *decimal)
 }
 
 static int sbtsi_read(struct device *dev, enum hwmon_sensor_types type,
-		      u32 attr, int channel, long *val)
+		u32 attr, int channel, long *val)
 {
 	struct sbtsi_data *data = dev_get_drvdata(dev);
 	s32 temp_int, temp_dec;
@@ -112,12 +84,6 @@ static int sbtsi_read(struct device *dev, enum hwmon_sensor_types type,
 		return -EINVAL;
 	}
 
-
-	if (temp_int < 0)
-		return temp_int;
-	if (temp_dec < 0)
-		return temp_dec;
-
 	*val = sbtsi_reg_to_mc(temp_int, temp_dec);
 	if (data->ext_range_mode)
 		*val -= SBTSI_TEMP_EXT_RANGE_ADJ;
@@ -126,7 +92,7 @@ static int sbtsi_read(struct device *dev, enum hwmon_sensor_types type,
 }
 
 static int sbtsi_write(struct device *dev, enum hwmon_sensor_types type,
-		       u32 attr, int channel, long val)
+		u32 attr, int channel, long val)
 {
 	struct sbtsi_data *data = dev_get_drvdata(dev);
 	int reg_int, reg_dec, err;
@@ -154,12 +120,15 @@ static int sbtsi_write(struct device *dev, enum hwmon_sensor_types type,
 	if (err)
 		return err;
 
-	return i2c_smbus_write_byte_data(data->client, reg_dec, temp_dec);
+	err = i2c_smbus_write_byte_data(data->client, reg_dec, temp_dec);
+	if (err)
+		return err;
+	return 0;
 }
 
 static umode_t sbtsi_is_visible(const void *data,
-				enum hwmon_sensor_types type,
-				u32 attr, int channel)
+		enum hwmon_sensor_types type,
+		u32 attr, int channel)
 {
 	switch (type) {
 	case hwmon_temp:
@@ -195,56 +164,11 @@ static const struct hwmon_chip_info sbtsi_chip_info = {
 	.info = sbtsi_info,
 };
 
-static int sbtsi_probe(struct i2c_client *client)
+int create_sbtsi_hwmon_sensor_device(struct device *dev, struct sbtsi_data *data)
 {
-	struct device *dev = &client->dev;
 	struct device *hwmon_dev;
-	struct sbtsi_data *data;
-	int err;
 
-	data = devm_kzalloc(dev, sizeof(struct sbtsi_data), GFP_KERNEL);
-	if (!data)
-		return -ENOMEM;
-
-	data->client = client;
-
-	err = i2c_smbus_read_byte_data(data->client, SBTSI_REG_CONFIG);
-	if (err < 0)
-		return err;
-	data->ext_range_mode = FIELD_GET(BIT(SBTSI_CONFIG_EXT_RANGE_SHIFT), err);
-	data->read_order = FIELD_GET(BIT(SBTSI_CONFIG_READ_ORDER_SHIFT), err);
-
-	hwmon_dev = devm_hwmon_device_register_with_info(dev, client->name, data,
+	hwmon_dev = devm_hwmon_device_register_with_info(dev, "sbtsi", data,
 							 &sbtsi_chip_info, NULL);
-
 	return PTR_ERR_OR_ZERO(hwmon_dev);
 }
-
-static const struct i2c_device_id sbtsi_id[] = {
-	{"sbtsi"},
-	{}
-};
-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 = {
-	.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 <kunyi@google.com>");
-MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor");
-MODULE_LICENSE("GPL");
diff --git a/drivers/misc/amd-sbi/tsi.c b/drivers/misc/amd-sbi/tsi.c
new file mode 100644
index 000000000000..df754e60d84b
--- /dev/null
+++ b/drivers/misc/amd-sbi/tsi.c
@@ -0,0 +1,77 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * tsi.c - Side band TSI over I2C support for AMD out of band management.
+ *
+ * Copyright (c) 2020-2026, Google Inc.
+ * Copyright (c) 2020-2026, Kun Yi <kunyi@google.com>
+ */
+
+#include <linux/bitfield.h>
+#include "tsi-core.h"
+
+#define SBTSI_REG_CONFIG		0x03 /* RO */
+
+/*
+ * Bit for reporting value with temperature measurement range.
+ * bit == 0: Use default temperature range (0C to 255.875C).
+ * bit == 1: Use extended temperature range (-49C to +206.875C).
+ */
+#define SBTSI_CONFIG_EXT_RANGE_SHIFT   2
+
+/*
+ * ReadOrder bit specifies the reading order of integer and decimal part of
+ * CPU temperature for atomic reads. If bit == 0, reading integer part triggers
+ * latching of the decimal part, so integer part should be read first.
+ */
+
+#define SBTSI_CONFIG_READ_ORDER_SHIFT  5
+
+static int sbtsi_probe(struct i2c_client *client)
+{
+	struct device *dev = &client->dev;
+	struct sbtsi_data *data;
+	int err;
+
+	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
+	if (!data)
+		return -ENOMEM;
+
+	data->client = client;
+	err = i2c_smbus_read_byte_data(data->client, SBTSI_REG_CONFIG);
+	if (err < 0)
+		return err;
+	data->ext_range_mode = FIELD_GET(BIT(SBTSI_CONFIG_EXT_RANGE_SHIFT), err);
+	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);
+}
+
+static const struct i2c_device_id sbtsi_id[] = {
+	{"sbtsi"},
+	{}
+};
+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 = {
+	.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 <kunyi@google.com>");
+MODULE_DESCRIPTION("Hwmon driver for AMD SB-TSI emulated sensor");
+MODULE_LICENSE("GPL");
-- 
2.34.1