From 26cc3d3444564abb2650ad76957dbb3aac3cf1f8 Mon Sep 17 00:00:00 2001
From: Stephen Horvath <s.horvath@outlook.com.au>
Date: Sun, 29 Jun 2025 11:50:53 +1000
Subject: [PATCH] drm/i915/hwmon: Expose VRAM Temperature
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This patch adds the VRAM temperature to the i915 hwmon driver. The
temperature is exposed through the temp2_input sysfs attribute.

$ sensors
i915-pci-0300
Adapter: PCI adapter
in0: 663.00 mV
fan1: 746 RPM
temp1: +49.0°C
temp2: +52.0°C
power1: N/A  (max = 190.00 W, rated max =   0.00 W)
energy1: 25.04 kJ

Signed-off-by: Stephen Horvath <s.horvath@outlook.com.au>
---
 drivers/gpu/drm/i915/i915_hwmon.c        | 41 ++++++++++++++++--------
 drivers/gpu/drm/i915/intel_mchbar_regs.h |  2 ++
 2 files changed, 30 insertions(+), 13 deletions(-)

diff --git a/drivers/gpu/drm/i915/i915_hwmon.c b/drivers/gpu/drm/i915/i915_hwmon.c
index 7dfe1784153f..7d04b6221f4b 100644
--- a/drivers/gpu/drm/i915/i915_hwmon.c
+++ b/drivers/gpu/drm/i915/i915_hwmon.c
@@ -40,6 +40,7 @@ struct hwm_reg {
 	i915_reg_t energy_status_all;
 	i915_reg_t energy_status_tile;
 	i915_reg_t fan_speed;
+	i915_reg_t vram_temp;
 };
 
 struct hwm_energy_info {
@@ -282,7 +283,7 @@ static const struct attribute_group *hwm_groups[] = {
 };
 
 static const struct hwmon_channel_info * const hwm_info[] = {
-	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),
+	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT, HWMON_T_INPUT),
 	HWMON_CHANNEL_INFO(in, HWMON_I_INPUT),
 	HWMON_CHANNEL_INFO(power, HWMON_P_MAX | HWMON_P_RATED_MAX | HWMON_P_CRIT),
 	HWMON_CHANNEL_INFO(energy, HWMON_E_INPUT),
@@ -314,34 +315,46 @@ static int hwm_pcode_write_i1(struct drm_i915_private *i915, u32 uval)
 }
 
 static umode_t
-hwm_temp_is_visible(const struct hwm_drvdata *ddat, u32 attr)
+hwm_temp_is_visible(const struct hwm_drvdata *ddat, u32 attr, int chan)
 {
 	struct i915_hwmon *hwmon = ddat->hwmon;
 
-	if (attr == hwmon_temp_input && i915_mmio_reg_valid(hwmon->rg.pkg_temp))
+	if (attr == hwmon_temp_input && chan == 0 &&
+		i915_mmio_reg_valid(hwmon->rg.pkg_temp))
+		return 0444;
+
+	if (attr == hwmon_temp_input && chan == 1 &&
+		i915_mmio_reg_valid(hwmon->rg.vram_temp))
 		return 0444;
 
 	return 0;
 }
 
 static int
-hwm_temp_read(struct hwm_drvdata *ddat, u32 attr, long *val)
+hwm_temp_read(struct hwm_drvdata *ddat, u32 attr, int chan, long *val)
 {
 	struct i915_hwmon *hwmon = ddat->hwmon;
 	intel_wakeref_t wakeref;
 	u32 reg_val;
 
-	switch (attr) {
-	case hwmon_temp_input:
+	if (attr != hwmon_temp_input)
+		return -EOPNOTSUPP;
+
+	switch (chan) {
+	case 0:
 		with_intel_runtime_pm(ddat->uncore->rpm, wakeref)
 			reg_val = intel_uncore_read(ddat->uncore, hwmon->rg.pkg_temp);
-
-		/* HW register value is in degrees Celsius, convert to millidegrees. */
-		*val = REG_FIELD_GET(TEMP_MASK, reg_val) * MILLIDEGREE_PER_DEGREE;
-		return 0;
+		break;
+	case 1:
+		with_intel_runtime_pm(ddat->uncore->rpm, wakeref)
+			reg_val = intel_uncore_read(ddat->uncore, hwmon->rg.vram_temp);
+		break;
 	default:
-		return -EOPNOTSUPP;
+		return -EINVAL;
 	}
+	/* HW register value is in degrees Celsius, convert to millidegrees. */
+	*val = REG_FIELD_GET(TEMP_MASK, reg_val) * MILLIDEGREE_PER_DEGREE;
+	return 0;
 }
 
 static umode_t
@@ -727,7 +740,7 @@ hwm_is_visible(const void *drvdata, enum hwmon_sensor_types type,
 
 	switch (type) {
 	case hwmon_temp:
-		return hwm_temp_is_visible(ddat, attr);
+		return hwm_temp_is_visible(ddat, attr, channel);
 	case hwmon_in:
 		return hwm_in_is_visible(ddat, attr);
 	case hwmon_power:
@@ -751,7 +764,7 @@ hwm_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
 
 	switch (type) {
 	case hwmon_temp:
-		return hwm_temp_read(ddat, attr, val);
+		return hwm_temp_read(ddat, attr, channel, val);
 	case hwmon_in:
 		return hwm_in_read(ddat, attr, val);
 	case hwmon_power:
@@ -855,6 +868,7 @@ hwm_get_preregistration_info(struct drm_i915_private *i915)
 		hwmon->rg.energy_status_all = PCU_PACKAGE_ENERGY_STATUS;
 		hwmon->rg.energy_status_tile = INVALID_MMIO_REG;
 		hwmon->rg.fan_speed = PCU_PWM_FAN_SPEED;
+		hwmon->rg.vram_temp = IS_DG2(i915) ? BMG_VRAM_TEMPERATURE : INVALID_MMIO_REG;
 	} else {
 		hwmon->rg.pkg_temp = INVALID_MMIO_REG;
 		hwmon->rg.pkg_power_sku_unit = INVALID_MMIO_REG;
@@ -863,6 +877,7 @@ hwm_get_preregistration_info(struct drm_i915_private *i915)
 		hwmon->rg.energy_status_all = INVALID_MMIO_REG;
 		hwmon->rg.energy_status_tile = INVALID_MMIO_REG;
 		hwmon->rg.fan_speed = INVALID_MMIO_REG;
+		hwmon->rg.vram_temp = INVALID_MMIO_REG;
 	}
 
 	with_intel_runtime_pm(uncore->rpm, wakeref) {
diff --git a/drivers/gpu/drm/i915/intel_mchbar_regs.h b/drivers/gpu/drm/i915/intel_mchbar_regs.h
index dc2477179c3e..94a9f4680c41 100644
--- a/drivers/gpu/drm/i915/intel_mchbar_regs.h
+++ b/drivers/gpu/drm/i915/intel_mchbar_regs.h
@@ -255,4 +255,6 @@
 
 #define BXT_GT_PERF_STATUS			_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x7070)
 
+#define BMG_VRAM_TEMPERATURE			_MMIO(0x1382c0)
+
 #endif /* __INTEL_MCHBAR_REGS */