drm/i915/hwmon: expose package temperature

Add hwmon support for temp1_input attribute, which will expose package
temperature in millidegree Celsius. With this in place we can monitor
package temperature using lm-sensors tool.

$ sensors
i915-pci-0300
Adapter: PCI adapter
in0: 990.00 mV
fan1: 1260 RPM
temp1: +45.0°C
power1: N/A (max = 35.00 W)
energy1: 12.62 kJ

v2: Use switch case (Anshuman)
v3: Comment adjustment (Riana)

Closes: https://gitlab.freedesktop.org/drm/i915/kernel/-/issues/11276
Signed-off-by: Raag Jadav <[e-mail]>
Reviewed-by: Anshuman Gupta <[e-mail]>
Reviewed-by: Andi Shyti <[e-mail]>
Reviewed-by: Riana Tauro <[e-mail]>
Signed-off-by: Andi Shyti <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon

···
 Description:	RO. Fan speed of device in RPM.
 
 		Only supported for particular Intel i915 graphics platforms.
+
+What:		/sys/bus/pci/drivers/i915/.../hwmon/hwmon<i>/temp1_input
+Date:		November 2024
+KernelVersion:	6.12
+Contact:	[e-mail]
+Description:	RO. GPU package temperature in millidegree Celsius.
+
+		Only supported for particular Intel i915 graphics platforms.

drivers/gpu/drm/i915/i915_hwmon.c

···
 #include <linux/hwmon-sysfs.h>
 #include <linux/jiffies.h>
 #include <linux/types.h>
+#include <linux/units.h>
 
 #include "i915_drv.h"
 #include "i915_hwmon.h"
···
 
 struct hwm_reg {
 	i915_reg_t gt_perf_status;
+	i915_reg_t pkg_temp;
 	i915_reg_t pkg_power_sku_unit;
 	i915_reg_t pkg_power_sku;
 	i915_reg_t pkg_rapl_limit;
···
 };
 
 static const struct hwmon_channel_info * const hwm_info[] = {
+	HWMON_CHANNEL_INFO(temp, 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),
···
 {
 	return  snb_pcode_write_p(&i915->uncore, PCODE_POWER_SETUP,
 				  POWER_SETUP_SUBCOMMAND_WRITE_I1, 0, uval);
+}
+
+static umode_t
+hwm_temp_is_visible(const struct hwm_drvdata *ddat, u32 attr)
+{
+	struct i915_hwmon *hwmon = ddat->hwmon;
+
+	if (attr == hwmon_temp_input && i915_mmio_reg_valid(hwmon->rg.pkg_temp))
+		return 0444;
+
+	return 0;
+}
+
+static int
+hwm_temp_read(struct hwm_drvdata *ddat, u32 attr, long *val)
+{
+	struct i915_hwmon *hwmon = ddat->hwmon;
+	intel_wakeref_t wakeref;
+	u32 reg_val;
+
+	switch (attr) {
+	case hwmon_temp_input:
+		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;
+	default:
+		return -EOPNOTSUPP;
+	}
 }
 
 static umode_t
···
 	struct hwm_drvdata *ddat = (struct hwm_drvdata *)drvdata;
 
 	switch (type) {
+	case hwmon_temp:
+		return hwm_temp_is_visible(ddat, attr);
 	case hwmon_in:
 		return hwm_in_is_visible(ddat, attr);
 	case hwmon_power:
···
 	struct hwm_drvdata *ddat = dev_get_drvdata(dev);
 
 	switch (type) {
+	case hwmon_temp:
+		return hwm_temp_read(ddat, attr, val);
 	case hwmon_in:
 		return hwm_in_read(ddat, attr, val);
 	case hwmon_power:
···
 	hwmon->rg.gt_perf_status = GEN12_RPSTAT1;
 
 	if (IS_DG1(i915) || IS_DG2(i915)) {
+		hwmon->rg.pkg_temp = PCU_PACKAGE_TEMPERATURE;
 		hwmon->rg.pkg_power_sku_unit = PCU_PACKAGE_POWER_SKU_UNIT;
 		hwmon->rg.pkg_power_sku = PCU_PACKAGE_POWER_SKU;
 		hwmon->rg.pkg_rapl_limit = PCU_PACKAGE_RAPL_LIMIT;
···
 		hwmon->rg.energy_status_tile = INVALID_MMIO_REG;
 		hwmon->rg.fan_speed = PCU_PWM_FAN_SPEED;
 	} else {
+		hwmon->rg.pkg_temp = INVALID_MMIO_REG;
 		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;

drivers/gpu/drm/i915/intel_mchbar_regs.h

···
 #define PCU_PACKAGE_ENERGY_STATUS              _MMIO(MCHBAR_MIRROR_BASE_SNB + 0x593c)
 
 #define GEN6_GT_PERF_STATUS			_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x5948)
+
+#define PCU_PACKAGE_TEMPERATURE			_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x5978)
+#define   TEMP_MASK				REG_GENMASK(7, 0)
+
 #define GEN6_RP_STATE_LIMITS			_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x5994)
 #define GEN6_RP_STATE_CAP			_MMIO(MCHBAR_MIRROR_BASE_SNB + 0x5998)
 #define   RP0_CAP_MASK				REG_GENMASK(7, 0)