On Fri, Aug 19, 2022 at 01:35:52PM +0300, Jani Nikula wrote:
> On Fri, 19 Aug 2022, Badal Nilawar <badal.nilawar@xxxxxxxxx> wrote:
> > From: Dale B Stimson <dale.b.stimson@xxxxxxxxx>
> >
> > 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)
>
> Is this really what we want to do?
>
> In my books, it's a misconfiguration to have CONFIG_HWMON=m with
> CONFIG_DRM_I915=y. That's really the problematic combo, not just
> CONFIG_HWMON=m, right? Why do we allow it at the kconfig level, and then
> have ugly hacks around it at the code level? Especially as
> CONFIG_DRM_I915=y should really be thought of as a corner case.
>
> So why not do this in i915 Kconfig:
>
> config DRM_I915
> ...
> depends on HWMON || HWMON=n
>
Ok with me, but not my call to make. The ifdef should then use
IS_ENABLED(), though.
Guenter
> Which rejects the CONFIG_HWMON=m && CONFIG_DRM_I915=y combo.
>
> >
> > Cc: Guenter Roeck <linux@xxxxxxxxxxxx>
> > Signed-off-by: Dale B Stimson <dale.b.stimson@xxxxxxxxx>
> > Signed-off-by: Ashutosh Dixit <ashutosh.dixit@xxxxxxxxx>
> > Signed-off-by: Riana Tauro <riana.tauro@xxxxxxxxx>
> > Signed-off-by: Badal Nilawar <badal.nilawar@xxxxxxxxx>
> > ---
> > drivers/gpu/drm/i915/Makefile | 3 +
> > drivers/gpu/drm/i915/i915_driver.c | 7 ++
> > drivers/gpu/drm/i915/i915_drv.h | 2 +
> > drivers/gpu/drm/i915/i915_hwmon.c | 135 +++++++++++++++++++++++++++++
> > drivers/gpu/drm/i915/i915_hwmon.h | 20 +++++
> > 5 files changed, 167 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 522ef9b4aff3..2b235f747490 100644
> > --- a/drivers/gpu/drm/i915/Makefile
> > +++ b/drivers/gpu/drm/i915/Makefile
> > @@ -208,6 +208,9 @@ 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
>
> Moreover, this builds i915_hwmon.o as part of i915.ko (or kernel as it's
> builtin) even if we can't use it!
>
>
> BR,
> Jani.
>
>
> > +
> > # 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 deb8a8b76965..62340cd01dde 100644
> > --- a/drivers/gpu/drm/i915/i915_driver.c
> > +++ b/drivers/gpu/drm/i915/i915_driver.c
> > @@ -80,6 +80,7 @@
> > #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"
> > @@ -736,6 +737,9 @@ static void i915_driver_register(struct drm_i915_private *dev_priv)
> >
> > intel_gt_driver_register(to_gt(dev_priv));
> >
> > +#if IS_REACHABLE(CONFIG_HWMON)
> > + i915_hwmon_register(dev_priv);
> > +#endif
> > intel_display_driver_register(dev_priv);
> >
> > intel_power_domains_enable(dev_priv);
> > @@ -762,6 +766,9 @@ static void i915_driver_unregister(struct drm_i915_private *dev_priv)
> >
> > intel_display_driver_unregister(dev_priv);
> >
> > +#if IS_REACHABLE(CONFIG_HWMON)
> > + i915_hwmon_unregister(dev_priv);
> > +#endif
> > intel_gt_driver_unregister(to_gt(dev_priv));
> >
> > i915_perf_unregister(dev_priv);
> > diff --git a/drivers/gpu/drm/i915/i915_drv.h b/drivers/gpu/drm/i915/i915_drv.h
> > index 086bbe8945d6..d437d588dec9 100644
> > --- a/drivers/gpu/drm/i915/i915_drv.h
> > +++ b/drivers/gpu/drm/i915/i915_drv.h
> > @@ -705,6 +705,8 @@ 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..5b80a0f024f0
> > --- /dev/null
> > +++ b/drivers/gpu/drm/i915/i915_hwmon.c
> > @@ -0,0 +1,135 @@
> > +// 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 "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..921ae76099d3
> > --- /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__
> > +
> > +#include <linux/device.h>
> > +#include <linux/mutex.h>
> > +#include <linux/types.h>
> > +#include "i915_reg.h"
> > +
> > +struct drm_i915_private;
> > +
> > +void i915_hwmon_register(struct drm_i915_private *i915);
> > +void i915_hwmon_unregister(struct drm_i915_private *i915);
> > +
> > +#endif /* __I915_HWMON_H__ */
>
> --
> Jani Nikula, Intel Open Source Graphics Center
