Re: [Intel-xe] [PATCH v2 1/6] drm/xe/hwmon: Add HWMON infrastructure

[Matthew Brost <matthew.brost@intel.com>]

On Wed, Jun 28, 2023 at 12:00:38AM +0530, Badal Nilawar wrote:
> The xe HWMON module will be used to expose voltage, power and energy
> values for dGfx. Here we set up xe hwmon infrastructure including xe
> hwmon registration, basic data structures and functions.
> This is port from i915 hwmon.
> 
> v2: Fix review comments (Riana)
> 
> Signed-off-by: Badal Nilawar <badal.nilawar@intel.com>
> ---
>  drivers/gpu/drm/xe/Makefile          |   3 +
>  drivers/gpu/drm/xe/xe_device.c       |   5 ++
>  drivers/gpu/drm/xe/xe_device_types.h |   2 +
>  drivers/gpu/drm/xe/xe_hwmon.c        | 116 +++++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_hwmon.h        |  22 +++++
>  5 files changed, 148 insertions(+)
>  create mode 100644 drivers/gpu/drm/xe/xe_hwmon.c
>  create mode 100644 drivers/gpu/drm/xe/xe_hwmon.h
> 
> diff --git a/drivers/gpu/drm/xe/Makefile b/drivers/gpu/drm/xe/Makefile
> index 4b82cb2773ad..e39d77037622 100644
> --- a/drivers/gpu/drm/xe/Makefile
> +++ b/drivers/gpu/drm/xe/Makefile
> @@ -113,6 +113,9 @@ xe-y += xe_bb.o \
>  	xe_wa.o \
>  	xe_wopcm.o
>  
> +# graphics hardware monitoring (HWMON) support
> +xe-$(CONFIG_HWMON) += xe_hwmon.o
> +
>  # i915 Display compat #defines and #includes
>  subdir-ccflags-$(CONFIG_DRM_XE_DISPLAY) += \
>  	-I$(srctree)/$(src)/display/ext \
> diff --git a/drivers/gpu/drm/xe/xe_device.c b/drivers/gpu/drm/xe/xe_device.c
> index c7985af85a53..0fcd60037d66 100644
> --- a/drivers/gpu/drm/xe/xe_device.c
> +++ b/drivers/gpu/drm/xe/xe_device.c
> @@ -34,6 +34,7 @@
>  #include "xe_vm.h"
>  #include "xe_vm_madvise.h"
>  #include "xe_wait_user_fence.h"
> +#include "xe_hwmon.h"
>  
>  static int xe_file_open(struct drm_device *dev, struct drm_file *file)
>  {
> @@ -328,6 +329,8 @@ int xe_device_probe(struct xe_device *xe)
>  
>  	xe_debugfs_register(xe);
>  
> +	xe_hwmon_register(xe);
> +
>  	err = drmm_add_action_or_reset(&xe->drm, xe_device_sanitize, xe);
>  	if (err)
>  		return err;
> @@ -354,6 +357,8 @@ static void xe_device_remove_display(struct xe_device *xe)
>  
>  void xe_device_remove(struct xe_device *xe)
>  {
> +	xe_hwmon_unregister(xe);
> +
>  	xe_device_remove_display(xe);
>  
>  	xe_display_unlink(xe);
> diff --git a/drivers/gpu/drm/xe/xe_device_types.h b/drivers/gpu/drm/xe/xe_device_types.h
> index 0226d44a6af2..21bff0e610a1 100644
> --- a/drivers/gpu/drm/xe/xe_device_types.h
> +++ b/drivers/gpu/drm/xe/xe_device_types.h
> @@ -332,6 +332,8 @@ struct xe_device {
>  	/** @d3cold_allowed: Indicates if d3cold is a valid device state */
>  	bool d3cold_allowed;
>  
> +	struct xe_hwmon *hwmon;
> +

You likely need a 'struct xe_hwmon' forward declaration at the top of
the file.

>  	/* private: */
>  
>  #if IS_ENABLED(CONFIG_DRM_XE_DISPLAY)
> diff --git a/drivers/gpu/drm/xe/xe_hwmon.c b/drivers/gpu/drm/xe/xe_hwmon.c
> new file mode 100644
> index 000000000000..8f653fdf4ad5
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_hwmon.c
> @@ -0,0 +1,116 @@
> +// SPDX-License-Identifier: MIT
> +/*
> + * Copyright © 2023 Intel Corporation
> + */
> +
> +#include <linux/hwmon.h>
> +
> +#include "regs/xe_gt_regs.h"
> +#include "xe_device.h"
> +#include "xe_hwmon.h"
> +
> +struct hwm_drvdata {
> +	struct xe_hwmon *hwmon;
> +	struct device *hwmon_dev;
> +	char name[12];
> +};
> +
> +struct xe_hwmon {
> +	struct hwm_drvdata ddat;
> +	struct mutex hwmon_lock;
> +};
> +

These two structures look very goofy, e.g. why two 2 structs instead of
1, why a back pointer in 'struct hwm_drvdata' rather than using
container_of? Just make this one structure?

> +static const struct hwmon_channel_info *hwm_info[] = {
> +	NULL
> +};
> +
> +static umode_t
> +hwm_is_visible(const void *drvdata, enum hwmon_sensor_types type,

Nit and matter of opinion but...

s/hwm_is_visible/xe_hwmon_is_visible

> +	       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)

s/hwm_read/xe_hwmon_read

> +{
> +	switch (type) {
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static int
> +hwm_write(struct device *dev, enum hwmon_sensor_types type, u32 attr,
> +	  int channel, long val)
> +{

s/hwm_write/xe_hwmon_write

> +	switch (type) {
> +	default:
> +		return -EOPNOTSUPP;
> +	}
> +}
> +
> +static const struct hwmon_ops hwm_ops = {

s/hwm_ops/xe_hwmon_ops

> +	.is_visible = hwm_is_visible,
> +	.read = hwm_read,
> +	.write = hwm_write,
> +};
> +
> +static const struct hwmon_chip_info hwm_chip_info = {

s/hwm_chip_info/xe_hwmon_chip_info

> +	.ops = &hwm_ops,
> +	.info = hwm_info,
> +};
> +
> +static void
> +hwm_get_preregistration_info(struct xe_device *xe)
> +{
> +}
> +
> +void xe_hwmon_register(struct xe_device *xe)
> +{
> +	struct device *dev = xe->drm.dev;
> +	struct xe_hwmon *hwmon;
> +	struct device *hwmon_dev;
> +	struct hwm_drvdata *ddat;
> +
> +	/* hwmon is available only for dGfx */
> +	if (!IS_DGFX(xe))
> +		return;
> +
> +	hwmon = devm_kzalloc(dev, sizeof(*hwmon), GFP_KERNEL);
> +	if (!hwmon)
> +		return;
> +
> +	xe->hwmon = hwmon;
> +	mutex_init(&hwmon->hwmon_lock);

drmm_mutex_init

Matt

> +	ddat = &hwmon->ddat;
> +
> +	ddat->hwmon = hwmon;
> +	snprintf(ddat->name, sizeof(ddat->name), "xe");
> +
> +	hwm_get_preregistration_info(xe);
> +
> +	drm_dbg(&xe->drm, "Register HWMON interface\n");
> +
> +	/*  hwmon_dev points to device hwmon<i> */
> +	hwmon_dev = devm_hwmon_device_register_with_info(dev, ddat->name,
> +							 ddat,
> +							 &hwm_chip_info,
> +							 NULL);
> +	if (IS_ERR(hwmon_dev)) {
> +		drm_warn(&xe->drm, "Fail to register xe hwmon\n");
> +		xe->hwmon = NULL;
> +		return;
> +	}
> +
> +	ddat->hwmon_dev = hwmon_dev;
> +}
> +
> +void xe_hwmon_unregister(struct xe_device *xe)
> +{
> +	xe->hwmon = NULL;
> +}
> diff --git a/drivers/gpu/drm/xe/xe_hwmon.h b/drivers/gpu/drm/xe/xe_hwmon.h
> new file mode 100644
> index 000000000000..a078eeb0a68b
> --- /dev/null
> +++ b/drivers/gpu/drm/xe/xe_hwmon.h
> @@ -0,0 +1,22 @@
> +/* SPDX-License-Identifier: MIT */
> +
> +/*
> + * Copyright © 2023 Intel Corporation
> + */
> +
> +#ifndef __XE_HWMON_H__
> +#define __XE_HWMON_H__
> +
> +#include <linux/types.h>
> +
> +struct xe_device;
> +
> +#if IS_REACHABLE(CONFIG_HWMON)
> +void xe_hwmon_register(struct xe_device *xe);
> +void xe_hwmon_unregister(struct xe_device *xe);
> +#else
> +static inline void xe_hwmon_register(struct xe_device *xe) { };
> +static inline void xe_hwmon_unregister(struct xe_device *xe) { };
> +#endif
> +
> +#endif /* __XE_HWMON_H__ */
> -- 
> 2.25.1
>