[PATCH v4] drm/i915/hwmon: expose fan speed

Raag Jadav
2024-08-09T05:53:20Z

Add hwmon support for fan1_input attribute, which will expose fan speed
in RPM. With this in place we can monitor fan speed using lm-sensors tool.

$ sensors
i915-pci-0300
Adapter: PCI adapter
in0: 653.00 mV
fan1: 3833 RPM
power1: N/A (max = 43.00 W)
energy1: 32.02 kJ

v2:
- Add mutex protection
- Handle overflow
- Add ABI documentation
- Aesthetic adjustments (Riana)

v3:
- Declare rotations as "long" and drop redundant casting
- Change date and version in ABI documentation
- Add commenter name in changelog (Riana)

v4:
- Fix wakeref leak
- Drop switch case and simplify hwm_fan_xx() (Andi)

Signed-off-by: Raag Jadav <raag.jadav@intel.com>
Reviewed-by: Riana Tauro <riana.tauro@intel.com>
---
.../ABI/testing/sysfs-driver-intel-i915-hwmon | 8 ++
drivers/gpu/drm/i915/gt/intel_gt_regs.h | 2 +
drivers/gpu/drm/i915/i915_hwmon.c | 81 +++++++++++++++++++
3 files changed, 91 insertions(+)

diff --git a/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon b/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon
index 92fe7c5c5ac1..be4141a7522f 100644
--- a/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon
+++ b/Documentation/ABI/testing/sysfs-driver-intel-i915-hwmon
@@ -75,3 +75,11 @@ Description: RO. Energy input of device or gt in microjoules.
for the gt.

Only supported for particular Intel i915 graphics platforms.
+
+What: /sys/bus/pci/drivers/i915/.../hwmon/hwmon/fan1_input
+Date: November 2024
+KernelVersion: 6.12
+Contact: intel-gfx@lists.freedesktop.org
+Description: RO. Fan speed of device in RPM.
+
+ 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 e42b3a5d4e63..57a3c83d3655 100644
--- a/drivers/gpu/drm/i915/gt/intel_gt_regs.h
+++ b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
@@ -1553,6 +1553,8 @@
#define VLV_RENDER_C0_COUNT _MMIO(0x138118)
#define VLV_MEDIA_C0_COUNT _MMIO(0x13811c)

+#define PCU_PWM_FAN_SPEED _MMIO(0x138140)
+
#define GEN12_RPSTAT1 _MMIO(0x1381b4)
#define GEN12_VOLTAGE_MASK REG_GENMASK(10, 0)
#define GEN12_CAGF_MASK REG_GENMASK(19, 11)
diff --git a/drivers/gpu/drm/i915/i915_hwmon.c b/drivers/gpu/drm/i915/i915_hwmon.c
index 49db3e09826c..bafa5a11ed0f 100644
--- a/drivers/gpu/drm/i915/i915_hwmon.c
+++ b/drivers/gpu/drm/i915/i915_hwmon.c
@@ -36,6 +36,7 @@ struct hwm_reg {
i915_reg_t pkg_rapl_limit;
i915_reg_t energy_status_all;
i915_reg_t energy_status_tile;
+ i915_reg_t fan_speed;
};

struct hwm_energy_info {
@@ -43,11 +44,17 @@ struct hwm_energy_info {
long accum_energy; /* Accumulated energy for energy1_input */
};

+struct hwm_fan_info {
+ u32 reg_val_prev;
+ u32 time_prev;
+};
+
struct hwm_drvdata {
struct i915_hwmon *hwmon;
struct intel_uncore *uncore;
struct device *hwmon_dev;
struct hwm_energy_info ei; /* Energy info for energy1_input */
+ struct hwm_fan_info fi; /* Fan info for fan1_input */
char name[12];
int gt_n;
bool reset_in_progress;
@@ -276,6 +283,7 @@ static const struct hwmon_channel_info * const hwm_info[] = {
HWMON_CHANNEL_INFO(power, HWMON_P_MAX | HWMON_P_RATED_MAX | HWMON_P_CRIT),
HWMON_CHANNEL_INFO(energy, HWMON_E_INPUT),
HWMON_CHANNEL_INFO(curr, HWMON_C_CRIT),
+ HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT),
NULL
};

@@ -613,6 +621,63 @@ hwm_curr_write(struct hwm_drvdata *ddat, u32 attr, long val)
}
}

+static umode_t
+hwm_fan_is_visible(const struct hwm_drvdata *ddat, u32 attr)
+{
+ struct i915_hwmon *hwmon = ddat->hwmon;
+
+ return attr == hwmon_fan_input &&
+ i915_mmio_reg_valid(hwmon->rg.fan_speed) ? 0444 : 0;
+}
+
+static int
+hwm_fan_read(struct hwm_drvdata *ddat, u32 attr, long *val)
+{
+ struct i915_hwmon *hwmon = ddat->hwmon;
+ struct hwm_fan_info *fi = &ddat->fi;
+ u32 reg_val, pulses, time, time_now;
+ intel_wakeref_t wakeref;
+ long rotations;
+ int ret = 0;
+
+ if (attr != hwmon_fan_input)
+ return -EOPNOTSUPP;
+
+ wakeref = intel_runtime_pm_get(ddat->uncore->rpm);
+ mutex_lock(&hwmon->hwmon_lock);
+
+ reg_val = intel_uncore_read(ddat->uncore, hwmon->rg.fan_speed);
+ time_now = jiffies_to_msecs(jiffies);
+
+ /* Handle overflow */
+ if (reg_val >= fi->reg_val_prev)
+ pulses = reg_val - fi->reg_val_prev;
+ else
+ pulses = UINT_MAX - fi->reg_val_prev + reg_val;
+
+ /*
+ * HW register value is accumulated count of pulses from
+ * PWM fan with the scale of 2 pulses per rotation.
+ */
+ rotations = pulses >> 1;
+ time = time_now - fi->time_prev;
+
+ if (unlikely(!time)) {
+ ret = -EAGAIN;
+ goto exit;
+ }
+
+ /* Convert to minutes for calculating RPM */
+ *val = DIV_ROUND_UP(rotations * (60 * MSEC_PER_SEC), time);
+
+ fi->reg_val_prev = reg_val;
+ fi->time_prev = time_now;
+exit:
+ mutex_unlock(&hwmon->hwmon_lock);
+ intel_runtime_pm_put(ddat->uncore->rpm, wakeref);
+ return ret;
+}
+
static umode_t
hwm_is_visible(const void *drvdata, enum hwmon_sensor_types type,
u32 attr, int channel)
@@ -628,6 +693,8 @@ hwm_is_visible(const void *drvdata, enum hwmon_sensor_types type,
return hwm_energy_is_visible(ddat, attr);
case hwmon_curr:
return hwm_curr_is_visible(ddat, attr);
+ case hwmon_fan:
+ return hwm_fan_is_visible(ddat, attr);
default:
return 0;
}
@@ -648,6 +715,8 @@ hwm_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
return hwm_energy_read(ddat, attr, val);
case hwmon_curr:
return hwm_curr_read(ddat, attr, val);
+ case hwmon_fan:
+ return hwm_fan_read(ddat, attr, val);
default:
return -EOPNOTSUPP;
}
@@ -739,12 +808,14 @@ hwm_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.fan_speed = PCU_PWM_FAN_SPEED;
} 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.fan_speed = INVALID_MMIO_REG;
}

with_intel_runtime_pm(uncore->rpm, wakeref) {
@@ -755,6 +826,16 @@ hwm_get_preregistration_info(struct drm_i915_private *i915)
if (i915_mmio_reg_valid(hwmon->rg.pkg_power_sku_unit))
val_sku_unit = intel_uncore_read(uncore,
hwmon->rg.pkg_power_sku_unit);
+
+ /*
+ * Store the initial fan register value, so that we can use it for
+ * initial fan speed calculation.
+ */
+ if (i915_mmio_reg_valid(hwmon->rg.fan_speed)) {
+ ddat->fi.reg_val_prev = intel_uncore_read(uncore,
+ hwmon->rg.fan_speed);
+ ddat->fi.time_prev = jiffies_to_msecs(jiffies);
+ }
}

hwmon->scl_shift_power = REG_FIELD_GET(PKG_PWR_UNIT, val_sku_unit);
--
2.34.1