[Deepin-Kernel-SIG] [linux 6.18.y] [FROMLIST] hwmon: raspberrypi: Add voltage input support

Documentation/hwmon/raspberrypi-hwmon.rst

@@ -20,6 +20,17 @@ undervoltage conditions.
 Sysfs entries
 -------------
 
-======================= ==================
+======================= ======================================================
+in0_input		Core voltage in millivolts
+in1_input		SDRAM controller voltage in millivolts
+in2_input		SDRAM I/O voltage in millivolts
+in3_input		SDRAM PHY voltage in millivolts
+in0_label		"core"
+in1_label		"sdram_c"
+in2_label		"sdram_i"
+in3_label		"sdram_p"
 in0_lcrit_alarm		Undervoltage alarm
-======================= ==================
+======================= ======================================================
+
+The voltage inputs and labels are only exposed if the firmware reports support
+for the corresponding voltage ID.

drivers/hwmon/raspberrypi-hwmon.c

@@ -5,6 +5,7 @@
  * Based on firmware/raspberrypi.c by Noralf Trønnes
  *
  * Copyright (C) 2018 Stefan Wahren <stefan.wahren@i2se.com>
+ * Copyright (C) 2026 Shubham Chakraborty <chakrabortyshubham66@gmail.com>
  */
 #include <linux/device.h>
 #include <linux/devm-helpers.h>
@@ -21,10 +22,18 @@
 struct rpi_hwmon_data {
 	struct device *hwmon_dev;
 	struct rpi_firmware *fw;
+	u32 valid_inputs;
 	u32 last_throttled;
 	struct delayed_work get_values_poll_work;
 };
 
+static const char * const rpi_hwmon_labels[] = {
+	"core",
+	"sdram_c",
+	"sdram_i",
+	"sdram_p",
+};
+
 static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
 {
 	u32 new_uv, old_uv, value;
@@ -56,6 +65,22 @@ static void rpi_firmware_get_throttled(struct rpi_hwmon_data *data)
 	hwmon_notify_event(data->hwmon_dev, hwmon_in, hwmon_in_lcrit_alarm, 0);
 }
 
+static int rpi_firmware_get_voltage(struct rpi_hwmon_data *data, u32 id,
+				    long *val)
+{
+	struct rpi_firmware_get_voltage_request packet =
+		RPI_FIRMWARE_GET_VOLTAGE_REQUEST(id);
+	int ret;
+
+	ret = rpi_firmware_property(data->fw, RPI_FIRMWARE_GET_VOLTAGE,
+				    &packet, sizeof(packet));
+	if (ret)
+		return ret;
+
+	*val = le32_to_cpu(packet.value) / 1000;
+	return 0;
+}
+
 static void get_values_poll(struct work_struct *work)
 {
 	struct rpi_hwmon_data *data;
@@ -77,19 +102,94 @@ static int rpi_read(struct device *dev, enum hwmon_sensor_types type,
 {
 	struct rpi_hwmon_data *data = dev_get_drvdata(dev);
 
-	*val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
+	if (type == hwmon_in) {
+		switch (attr) {
+		case hwmon_in_input:
+			switch (channel) {
+			case 0:
+				return rpi_firmware_get_voltage(data,
+						RPI_FIRMWARE_VOLT_ID_CORE,
+						val);
+			case 1:
+				return rpi_firmware_get_voltage(data,
+						RPI_FIRMWARE_VOLT_ID_SDRAM_C,
+						val);
+			case 2:
+				return rpi_firmware_get_voltage(data,
+						RPI_FIRMWARE_VOLT_ID_SDRAM_I,
+						val);
+			case 3:
+				return rpi_firmware_get_voltage(data,
+						RPI_FIRMWARE_VOLT_ID_SDRAM_P,
+						val);
+			default:
+				return -EOPNOTSUPP;
+			}
+		case hwmon_in_lcrit_alarm:
+			if (channel == 0) {
+				*val = !!(data->last_throttled & UNDERVOLTAGE_STICKY_BIT);
+				return 0;
+			}
+			return -EOPNOTSUPP;
+		default:
+			return -EOPNOTSUPP;
+		}
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static int rpi_read_string(struct device *dev, enum hwmon_sensor_types type,
+			   u32 attr, int channel, const char **str)
+{
+	if (type == hwmon_in && attr == hwmon_in_label) {
+		if (channel >= ARRAY_SIZE(rpi_hwmon_labels))
+			return -EOPNOTSUPP;
+
+		*str = rpi_hwmon_labels[channel];
+		return 0;
+	}
+
+	return -EOPNOTSUPP;
+}
+
+static umode_t rpi_is_visible(const void *_data, enum hwmon_sensor_types type,
+			      u32 attr, int channel)
+{
+	const struct rpi_hwmon_data *data = _data;
+
+	if (type == hwmon_in) {
+		switch (attr) {
+		case hwmon_in_input:
+		case hwmon_in_label:
+			if (!(data->valid_inputs & BIT(channel)))
+				return 0;
+			return 0444;
+		case hwmon_in_lcrit_alarm:
+			if (channel == 0)
+				return 0444;
+			return 0;
+		default:
+			return 0;
+		}
+	}
+
 	return 0;
 }
 
 static const struct hwmon_channel_info * const rpi_info[] = {
 	HWMON_CHANNEL_INFO(in,
-			   HWMON_I_LCRIT_ALARM),
+			   HWMON_I_INPUT | HWMON_I_LABEL | HWMON_I_LCRIT_ALARM,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL,
+			   HWMON_I_INPUT | HWMON_I_LABEL),
 	NULL
 };
 
 static const struct hwmon_ops rpi_hwmon_ops = {
-	.visible = 0444,
+	.is_visible = rpi_is_visible,
 	.read = rpi_read,
+	.read_string = rpi_read_string,
 };
 
 static const struct hwmon_chip_info rpi_chip_info = {
@@ -101,6 +201,7 @@ static int rpi_hwmon_probe(struct platform_device *pdev)
 {
 	struct device *dev = &pdev->dev;
 	struct rpi_hwmon_data *data;
+	long voltage;
 	int ret;
 
 	data = devm_kzalloc(dev, sizeof(*data), GFP_KERNEL);
@@ -110,6 +211,26 @@ static int rpi_hwmon_probe(struct platform_device *pdev)
 	/* Parent driver assure that firmware is correct */
 	data->fw = dev_get_drvdata(dev->parent);
 
+	ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_CORE,
+				       &voltage);
+	if (!ret)
+		data->valid_inputs |= BIT(0);
+
+	ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_C,
+				       &voltage);
+	if (!ret)
+		data->valid_inputs |= BIT(1);
+
+	ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_I,
+				       &voltage);
+	if (!ret)
+		data->valid_inputs |= BIT(2);
+
+	ret = rpi_firmware_get_voltage(data, RPI_FIRMWARE_VOLT_ID_SDRAM_P,
+				       &voltage);
+	if (!ret)
+		data->valid_inputs |= BIT(3);
+
 	data->hwmon_dev = devm_hwmon_device_register_with_info(dev, "rpi_volt",
 							       data,
 							       &rpi_chip_info,
@@ -159,6 +280,7 @@ static struct platform_driver rpi_hwmon_driver = {
 module_platform_driver(rpi_hwmon_driver);
 
 MODULE_AUTHOR("Stefan Wahren <wahrenst@gmx.net>");
+MODULE_AUTHOR("Shubham Chakraborty <chakrabortyshubham66@gmail.com>");
 MODULE_DESCRIPTION("Raspberry Pi voltage sensor driver");
 MODULE_LICENSE("GPL v2");
 MODULE_ALIAS("platform:raspberrypi-hwmon");