Re: [PATCH v1] drm/i915/hwmon: expose fan speed

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

On 12-07-2024 17:53, 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
> 
> Signed-off-by: Raag Jadav <raag.jadav@intel.com>
> ---
>   drivers/gpu/drm/i915/gt/intel_gt_regs.h |  2 +
>   drivers/gpu/drm/i915/i915_hwmon.c       | 71 +++++++++++++++++++++++++
>   2 files changed, 73 insertions(+)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_gt_regs.h b/drivers/gpu/drm/i915/gt/intel_gt_regs.h
> index e42b3a5d4e63..407d8152755a 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 GEN12_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..f829c7837d83 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 +621,55 @@ 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;
> +
> +	switch (attr) {
> +	case hwmon_fan_input:
> +		return i915_mmio_reg_valid(hwmon->rg.fan_speed) ? 0444 : 0;
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static int
> +hwm_fan_read(struct hwm_drvdata *ddat, u32 attr, long *val)
> +{
> +	struct i915_hwmon *hwmon = ddat->hwmon;
> +	u32 reg_val, rotation, time, time_now;
> +	intel_wakeref_t wakeref;
> +
> +	switch (attr) {
> +	case hwmon_fan_input:
> +		with_intel_runtime_pm(ddat->uncore->rpm, wakeref)Do we expect fan running when device is in D3? If not then we should use 
with_intel_runtime_pm_if_active here otherwise report fan speed 0.

Regards,
Badal
> +			reg_val = intel_uncore_read(ddat->uncore, hwmon->rg.fan_speed);
> +
> +		time_now = jiffies_to_msecs(jiffies);
> +
> +		/*
> +		 * HW register value is accumulated count of pulses from
> +		 * PWM fan with the scale of 2 pulses per rotation.
> +		 */
> +		rotation = (reg_val - ddat->fi.reg_val_prev) >> 1;
> +		time = time_now - ddat->fi.time_prev;
> +
> +		if (!time)
> +			return -EAGAIN;
> +
> +		/* Convert to minutes for calculating RPM. */
> +		*val = DIV_ROUND_UP((long)rotation * (60 * 1000), time);
> +
> +		ddat->fi.reg_val_prev = reg_val;
> +		ddat->fi.time_prev = time_now;
> +
> +		return 0;
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
>   static umode_t
>   hwm_is_visible(const void *drvdata, enum hwmon_sensor_types type,
>   	       u32 attr, int channel)
> @@ -628,6 +685,8 @@ 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 +707,8 @@ 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 +800,14 @@ 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 = GEN12_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) {
> @@ -771,6 +834,14 @@ hwm_get_preregistration_info(struct drm_i915_private *i915)
>   		for_each_gt(gt, i915, i)
>   			hwm_energy(&hwmon->ddat_gt[i], &energy);
>   	}
> +
> +	if (i915_mmio_reg_valid(hwmon->rg.fan_speed)) {
> +		/* Take initial readings and use it while calculating actual fan speed. */
> +		with_intel_runtime_pm(uncore->rpm, wakeref)
> +			ddat->fi.reg_val_prev = intel_uncore_read(ddat->uncore,
> +								  hwmon->rg.fan_speed);
> +		ddat->fi.time_prev = jiffies_to_msecs(jiffies);
> +	}
>   }
>   
>   void i915_hwmon_register(struct drm_i915_private *i915)