[Intel-gfx] [PATCH 3/3] drm/i915/hwmon: Add HWMON current voltage support

[Badal Nilawar <badal.nilawar@intel.com>]

From: Riana Tauro <riana.tauro@intel.com>

As part of the System Managemenent Interface (SMI), use the HWMON
subsystem to display current voltage

Cc: Anshuman Gupta <anshuman.gupta@intel.com>
Signed-off-by: Riana Tauro <riana.tauro@intel.com>
Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
---
 .../ABI/testing/sysfs-driver-intel-i915-hwmon |  8 +++
 drivers/gpu/drm/i915/gt/intel_gt_regs.h       |  4 ++
 drivers/gpu/drm/i915/i915_hwmon.c             | 57 +++++++++++++++++++
 drivers/gpu/drm/i915/i915_hwmon.h             |  1 +
 4 files changed, 70 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon b/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon
index 7574421c326f..c70e06dd0333 100644
--- a/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon
+++ b/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon
@@ -33,3 +33,11 @@ Contact:	dri-devel@lists.freedesktop.org
 Description:	RO. Card default power limit (default TDP setting).
 
 		Only supported for particular Intel i915 graphics platforms.
+
+What:		/sys/devices/.../hwmon/hwmon<i>/in0_input
+Date:		May 2022
+KernelVersion:	5.18
+Contact:	dri-devel@lists.freedesktop.org
+Description:	RO. Current Voltage in millivolt.
+
+		Only supported for particular Intel i915 graphics platforms.
diff --git a/drivers/gpu/drm/i915/gt/intel_gt_regs.h b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
index 7246eb870c7e..0adeca083de1 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_regs.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
@@ -1475,6 +1475,10 @@
 #define GEN6_GT_GFX_RC6p			_MMIO(0x13810c)
 #define GEN6_GT_GFX_RC6pp			_MMIO(0x138110)
 #define VLV_RENDER_C0_COUNT			_MMIO(0x138118)
+
+#define GEN12_RPSTAT1				_MMIO(0x1381b4)
+#define   GEN12_VOLTAGE_MASK			REG_GENMASK(10, 0)
+
 #define VLV_MEDIA_C0_COUNT			_MMIO(0x13811c)
 
 #define GEN11_GT_INTR_DW(x)			_MMIO(0x190018 + ((x) * 4))
diff --git a/drivers/gpu/drm/i915/i915_hwmon.c b/drivers/gpu/drm/i915/i915_hwmon.c
index b35c4de73f30..e5f4293a8fdb 100644
--- a/drivers/gpu/drm/i915/i915_hwmon.c
+++ b/drivers/gpu/drm/i915/i915_hwmon.c
@@ -12,6 +12,7 @@
 #include <linux/types.h>
 
 #include "i915_drv.h"
+#include "gt/intel_gt_regs.h"
 #include "i915_hwmon.h"
 #include "intel_mchbar_regs.h"
 
@@ -301,8 +302,23 @@ static const struct hwmon_channel_info i915_power = {
 	.config = i915_config_power,
 };
 
+/*
+ * HWMON SENSOR TYPE = hwmon_in
+ *  - Voltage Input value (in0_input)
+ */
+static const u32 i915_config_in[] = {
+	HWMON_I_INPUT,
+	0
+};
+
+static const struct hwmon_channel_info i915_in = {
+	.type = hwmon_in,
+	.config = i915_config_in,
+};
+
 static const struct hwmon_channel_info *i915_info[] = {
 	&i915_power,
+	&i915_in,
 	NULL
 };
 
@@ -370,6 +386,41 @@ i915_power_write(struct i915_hwmon_drvdata *ddat, u32 attr, int chan, long val)
 	return ret;
 }
 
+static umode_t
+i915_in_is_visible(const struct i915_hwmon_drvdata *ddat, u32 attr)
+{
+	struct drm_i915_private *i915 = ddat->dd_uncore->i915;
+
+	switch (attr) {
+	case hwmon_in_input:
+		return (IS_DG1(i915) || IS_DG2(i915)) ? 0444 : 0;
+	default:
+		return 0;
+	}
+
+	return 0444;
+}
+
+static int
+i915_in_read(struct i915_hwmon_drvdata *ddat, u32 attr, long *val)
+{
+	struct i915_hwmon *hwmon = ddat->dd_hwmon;
+	intel_wakeref_t wakeref;
+	u32 reg_value;
+
+	switch (attr) {
+	case hwmon_in_input:
+		with_intel_runtime_pm(ddat->dd_uncore->rpm, wakeref)
+			reg_value = intel_uncore_read(ddat->dd_uncore, hwmon->rg.gt_perf_status);
+		*val = DIV_ROUND_CLOSEST(REG_FIELD_GET(GEN12_VOLTAGE_MASK, reg_value) * 25, 10);
+		break;
+	default:
+		return -EOPNOTSUPP;
+	}
+
+	return 0;
+}
+
 static umode_t
 i915_is_visible(const void *drvdata, enum hwmon_sensor_types type,
 		u32 attr, int channel)
@@ -379,6 +430,8 @@ i915_is_visible(const void *drvdata, enum hwmon_sensor_types type,
 	switch (type) {
 	case hwmon_power:
 		return i915_power_is_visible(ddat, attr, channel);
+	case hwmon_in:
+		return i915_in_is_visible(ddat, attr);
 	default:
 		return 0;
 	}
@@ -393,6 +446,8 @@ i915_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
 	switch (type) {
 	case hwmon_power:
 		return i915_power_read(ddat, attr, channel, val);
+	case hwmon_in:
+		return i915_in_read(ddat, attr, val);
 	default:
 		return -EOPNOTSUPP;
 	}
@@ -440,12 +495,14 @@ i915_hwmon_get_preregistration_info(struct drm_i915_private *i915)
 		hwmon->rg.pkg_rapl_limit = PCU_PACKAGE_RAPL_LIMIT;
 		hwmon->rg.energy_status_all = PCU_PACKAGE_ENERGY_STATUS;
 		hwmon->rg.energy_status_tile = INVALID_MMIO_REG;
+		hwmon->rg.gt_perf_status = GEN12_RPSTAT1;
 	} else {
 		hwmon->rg.pkg_power_sku_unit = INVALID_MMIO_REG;
 		hwmon->rg.pkg_power_sku = INVALID_MMIO_REG;
 		hwmon->rg.pkg_rapl_limit = INVALID_MMIO_REG;
 		hwmon->rg.energy_status_all = INVALID_MMIO_REG;
 		hwmon->rg.energy_status_tile = INVALID_MMIO_REG;
+		hwmon->rg.gt_perf_status = INVALID_MMIO_REG;
 	}
 
 	wakeref = intel_runtime_pm_get(uncore->rpm);
diff --git a/drivers/gpu/drm/i915/i915_hwmon.h b/drivers/gpu/drm/i915/i915_hwmon.h
index 1c70a7056be7..90ae4acae74e 100644
--- a/drivers/gpu/drm/i915/i915_hwmon.h
+++ b/drivers/gpu/drm/i915/i915_hwmon.h
@@ -20,6 +20,7 @@ struct i915_hwmon_reg {
 	i915_reg_t pkg_rapl_limit;
 	i915_reg_t energy_status_all;
 	i915_reg_t energy_status_tile;
+	i915_reg_t gt_perf_status;
 };
 
 struct i915_energy_info {
-- 
2.25.1