Re: [PATCH v7] drm/i915/hwmon: expose fan speed

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

On 23-08-2024 09:15, Raag Jadav wrote:
> 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: Handle overflow, add mutex protection and ABI documentation
>      Aesthetic adjustments (Riana)
> v3: Change rotations data type, ABI date and version
> v4: Fix wakeref leak
>      Drop switch case and simplify hwm_fan_xx() (Andi)
> v5: Rework time calculation, aesthetic adjustments (Andy)
> v6: Drop redundant overflow logic (Andy)
>      Split fan_input_read() into dedicated helper (Badal)
> v7: Fix undefined reference to __udivdi3 for i386 (Andy)
> 
> Signed-off-by: Raag Jadav <raag.jadav@intel.com>
> Reviewed-by: Riana Tauro <riana.tauro@intel.com>
> Reviewed-by: Andi Shyti <andi.shyti@linux.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             | 88 +++++++++++++++++++
>   3 files changed, 98 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<i>/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..17d30f6b84b0 100644
> --- a/drivers/gpu/drm/i915/i915_hwmon.c
> +++ b/drivers/gpu/drm/i915/i915_hwmon.c
> @@ -5,6 +5,7 @@
>   
>   #include <linux/hwmon.h>
>   #include <linux/hwmon-sysfs.h>
> +#include <linux/jiffies.h>
>   #include <linux/types.h>
>   
>   #include "i915_drv.h"
> @@ -36,6 +37,7 @@ 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 +45,17 @@ struct hwm_energy_info {
>   	long accum_energy;			/* Accumulated energy for energy1_input */
>   };
>   
> +struct hwm_fan_info {
> +	u32 reg_val_prev;
> +	u64 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 +284,7 @@ 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 +622,69 @@ 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;
> +
> +	if (attr == hwmon_fan_input && i915_mmio_reg_valid(hwmon->rg.fan_speed))
> +		return 0444;
> +
> +	return 0;
> +}
> +
> +static int
> +hwm_fan_input_read(struct hwm_drvdata *ddat, long *val)
> +{
> +	struct i915_hwmon *hwmon = ddat->hwmon;
> +	struct hwm_fan_info *fi = &ddat->fi;
> +	u64 rotations, time_now, time;
> +	intel_wakeref_t wakeref;
> +	u32 reg_val;
> +	int ret = 0;
> +
> +	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 = get_jiffies_64();
> +
> +	/*
> +	 * HW register value is accumulated count of pulses from
> +	 * PWM fan with the scale of 2 pulses per rotation.
> +	 */
> +	rotations = (reg_val - fi->reg_val_prev) / 2;
> +
> +	time = jiffies_delta_to_msecs(time_now - fi->time_prev);
> +	if (unlikely(!time)) {
> +		ret = -EAGAIN;
> +		goto exit;
> +	}
> +
> +	/*
> +	 * Calculate fan speed in RPM by time averaging two subsequent
> +	 * readings in minutes.
> +	 * RPM = number of rotations * msecs per minute / time in msecs
> +	 */
> +	*val = DIV_ROUND_UP_ULL(rotations * (MSEC_PER_SEC * 60), 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 int
> +hwm_fan_read(struct hwm_drvdata *ddat, u32 attr, long *val)
> +{
> +	if (attr == hwmon_fan_input)
> +		return hwm_fan_input_read(ddat, val);
> +
> +	return -EOPNOTSUPP;
> +}
> +
>   static umode_t
>   hwm_is_visible(const void *drvdata, enum hwmon_sensor_types type,
>   	       u32 attr, int channel)
> @@ -628,6 +700,8 @@ 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 +722,8 @@ 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 +815,14 @@ 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 +833,16 @@ 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 = get_jiffies_64();
> +		}
Reviewed-by: Badal Nilawar <badal.nilawar@intel.com>
>   	}
>   
>   	hwmon->scl_shift_power = REG_FIELD_GET(PKG_PWR_UNIT, val_sku_unit);