Re: [Intel-gfx] [PATCH 1/7] drm/i915/hwmon: Add HWMON infrastructure

["Gupta, Anshuman" <anshuman.gupta@intel.com>]

On 9/16/2022 8:30 PM, Badal Nilawar wrote:
> From: Dale B Stimson <dale.b.stimson@intel.com>
> 
> The i915 HWMON module will be used to expose voltage, power and energy
> values for dGfx. Here we set up i915 hwmon infrastructure including i915
> hwmon registration, basic data structures and functions.
> 
> v2:
>    - Create HWMON infra patch (Ashutosh)
>    - Fixed review comments (Jani)
>    - Remove "select HWMON" from i915/Kconfig (Jani)
> v3: Use hwm_ prefix for static functions (Ashutosh)
> v4: s/#ifdef CONFIG_HWMON/#if IS_REACHABLE(CONFIG_HWMON)/ since the former
>      doesn't work if hwmon is compiled as a module (Guenter)
> v5: Fixed review comments (Jani)
> 
> Cc: Guenter Roeck <linux@roeck-us.net>
> Signed-off-by: Dale B Stimson <dale.b.stimson@intel.com>
> Signed-off-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
> Signed-off-by: Riana Tauro <riana.tauro@intel.com>
> Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
> Acked-by: Guenter Roeck <linux@roeck-us.net>
> Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>
Reviewed-by: Anshuman Gupta <anshuman.gupta@intel.com>

> ---
>   drivers/gpu/drm/i915/Makefile      |   3 +
>   drivers/gpu/drm/i915/i915_driver.c |   5 ++
>   drivers/gpu/drm/i915/i915_drv.h    |   2 +
>   drivers/gpu/drm/i915/i915_hwmon.c  | 136 +++++++++++++++++++++++++++++
>   drivers/gpu/drm/i915/i915_hwmon.h  |  20 +++++
>   5 files changed, 166 insertions(+)
>   create mode 100644 drivers/gpu/drm/i915/i915_hwmon.c
>   create mode 100644 drivers/gpu/drm/i915/i915_hwmon.h
> 
> diff --git a/drivers/gpu/drm/i915/Makefile b/drivers/gpu/drm/i915/Makefile
> index a26edcdadc21..66a6023e61a6 100644
> --- a/drivers/gpu/drm/i915/Makefile
> +++ b/drivers/gpu/drm/i915/Makefile
> @@ -209,6 +209,9 @@ i915-y += gt/uc/intel_uc.o \
>   # graphics system controller (GSC) support
>   i915-y += gt/intel_gsc.o
>   
> +# graphics hardware monitoring (HWMON) support
> +i915-$(CONFIG_HWMON) += i915_hwmon.o
> +
>   # modesetting core code
>   i915-y += \
>   	display/hsw_ips.o \
> diff --git a/drivers/gpu/drm/i915/i915_driver.c b/drivers/gpu/drm/i915/i915_driver.c
> index c459eb362c47..75655adb7bd3 100644
> --- a/drivers/gpu/drm/i915/i915_driver.c
> +++ b/drivers/gpu/drm/i915/i915_driver.c
> @@ -81,6 +81,7 @@
>   #include "i915_drm_client.h"
>   #include "i915_drv.h"
>   #include "i915_getparam.h"
> +#include "i915_hwmon.h"
>   #include "i915_ioc32.h"
>   #include "i915_ioctl.h"
>   #include "i915_irq.h"
> @@ -763,6 +764,8 @@ static void i915_driver_register(struct drm_i915_private *dev_priv)
>   	for_each_gt(gt, dev_priv, i)
>   		intel_gt_driver_register(gt);
>   
> +	i915_hwmon_register(dev_priv);
> +
>   	intel_display_driver_register(dev_priv);
>   
>   	intel_power_domains_enable(dev_priv);
> @@ -795,6 +798,8 @@ static void i915_driver_unregister(struct drm_i915_private *dev_priv)
>   	for_each_gt(gt, dev_priv, i)
>   		intel_gt_driver_unregister(gt);
>   
> +	i915_hwmon_unregister(dev_priv);
> +
>   	i915_perf_unregister(dev_priv);
>   	i915_pmu_unregister(dev_priv);
>   
> diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> index 9f9372931fd2..01a2caf42635 100644
> --- a/drivers/gpu/drm/i915/i915_drv.h
> +++ b/drivers/gpu/drm/i915/i915_drv.h
> @@ -353,6 +353,8 @@ struct drm_i915_private {
>   
>   	struct i915_perf perf;
>   
> +	struct i915_hwmon *hwmon;
> +
>   	/* Abstract the submission mechanism (legacy ringbuffer or execlists) away */
>   	struct intel_gt gt0;
>   
> diff --git a/drivers/gpu/drm/i915/i915_hwmon.c b/drivers/gpu/drm/i915/i915_hwmon.c
> new file mode 100644
> index 000000000000..103dd543a214
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/i915_hwmon.c
> @@ -0,0 +1,136 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2022 Intel Corporation
> + */
> +
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/types.h>
> +
> +#include "i915_drv.h"
> +#include "i915_hwmon.h"
> +#include "i915_reg.h"
> +#include "intel_mchbar_regs.h"
> +
> +struct hwm_reg {
> +};
> +
> +struct hwm_drvdata {
> +	struct i915_hwmon *hwmon;
> +	struct intel_uncore *uncore;
> +	struct device *hwmon_dev;
> +	char name[12];
> +};
> +
> +struct i915_hwmon {
> +	struct hwm_drvdata ddat;
> +	struct mutex hwmon_lock;		/* counter overflow logic and rmw */
> +	struct hwm_reg rg;
> +};
> +
> +static const struct hwmon_channel_info *hwm_info[] = {
> +	NULL
> +};
> +
> +static umode_t
> +hwm_is_visible(const void *drvdata, enum hwmon_sensor_types type,
> +	       u32 attr, int channel)
> +{
> +	switch (type) {
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static int
> +hwm_read(struct device *dev, enum hwmon_sensor_types type, u32 attr,
> +	 int channel, long *val)
> +{
> +	switch (type) {
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int
> +hwm_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
> +	  int channel, long val)
> +{
> +	switch (type) {
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static const struct hwmon_ops hwm_ops = {
> +	.is_visible = hwm_is_visible,
> +	.read = hwm_read,
> +	.write = hwm_write,
> +};
> +
> +static const struct hwmon_chip_info hwm_chip_info = {
> +	.ops = &hwm_ops,
> +	.info = hwm_info,
> +};
> +
> +static void
> +hwm_get_preregistration_info(struct drm_i915_private *i915)
> +{
> +}
> +
> +void i915_hwmon_register(struct drm_i915_private *i915)
> +{
> +	struct device *dev = i915->drm.dev;
> +	struct i915_hwmon *hwmon;
> +	struct device *hwmon_dev;
> +	struct hwm_drvdata *ddat;
> +
> +	/* hwmon is available only for dGfx */
> +	if (!IS_DGFX(i915))
> +		return;
> +
> +	hwmon = kzalloc(sizeof(*hwmon), GFP_KERNEL);
> +	if (!hwmon)
> +		return;
> +
> +	i915->hwmon = hwmon;
> +	mutex_init(&hwmon->hwmon_lock);
> +	ddat = &hwmon->ddat;
> +
> +	ddat->hwmon = hwmon;
> +	ddat->uncore = &i915->uncore;
> +	snprintf(ddat->name, sizeof(ddat->name), "i915");
> +
> +	hwm_get_preregistration_info(i915);
> +
> +	/*  hwmon_dev points to device hwmon<i> */
> +	hwmon_dev = hwmon_device_register_with_info(dev, ddat->name,
> +						    ddat,
> +						    &hwm_chip_info,
> +						    NULL);
> +	if (IS_ERR(hwmon_dev)) {
> +		mutex_destroy(&hwmon->hwmon_lock);
> +		i915->hwmon = NULL;
> +		kfree(hwmon);
> +		return;
> +	}
> +
> +	ddat->hwmon_dev = hwmon_dev;
> +}
> +
> +void i915_hwmon_unregister(struct drm_i915_private *i915)
> +{
> +	struct i915_hwmon *hwmon;
> +	struct hwm_drvdata *ddat;
> +
> +	hwmon = fetch_and_zero(&i915->hwmon);
> +	if (!hwmon)
> +		return;
> +
> +	ddat = &hwmon->ddat;
> +	if (ddat->hwmon_dev)
> +		hwmon_device_unregister(ddat->hwmon_dev);
> +
> +	mutex_destroy(&hwmon->hwmon_lock);
> +	kfree(hwmon);
> +}
> diff --git a/drivers/gpu/drm/i915/i915_hwmon.h b/drivers/gpu/drm/i915/i915_hwmon.h
> new file mode 100644
> index 000000000000..7ca9cf2c34c9
> --- /dev/null
> +++ b/drivers/gpu/drm/i915/i915_hwmon.h
> @@ -0,0 +1,20 @@
> +/* SPDX-License-Identifier: MIT */
> +
> +/*
> + * Copyright © 2022 Intel Corporation
> + */
> +
> +#ifndef __I915_HWMON_H__
> +#define __I915_HWMON_H__
> +
> +struct drm_i915_private;
> +
> +#if IS_REACHABLE(CONFIG_HWMON)
> +void i915_hwmon_register(struct drm_i915_private *i915);
> +void i915_hwmon_unregister(struct drm_i915_private *i915);
> +#else
> +static inline void i915_hwmon_register(struct drm_i915_private *i915) { };
> +static inline void i915_hwmon_unregister(struct drm_i915_private *i915) { };
> +#endif
> +
> +#endif /* __I915_HWMON_H__ */