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Message-ID: <92415bd8-4231-4c68-8034-e4f7a0ea5651@gmx.de>
Date: Tue, 28 May 2024 00:30:40 +0200
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Subject: Re: [PATCH v8] ACPI: fan: Add hwmon support
To: "Rafael J. Wysocki" <rafael@kernel.org>
Cc: mlj@danelec.com, rafael.j.wysocki@intel.com, lenb@kernel.org,
 jdelvare@suse.com, andy.shevchenko@gmail.com, linux@roeck-us.net,
 linux@weissschuh.net, ilpo.jarvinen@linux.intel.com,
 linux-acpi@vger.kernel.org, linux-hwmon@vger.kernel.org,
 linux-kernel@vger.kernel.org, platform-driver-x86@vger.kernel.org
References: <20240510201242.3886-1-W_Armin@gmx.de>
 <CAJZ5v0gu=yvFeXH4uwHeAQZ8p1JyCs8uuiKzr6F+yNkD2E1ZAA@mail.gmail.com>
Content-Language: en-US
From: Armin Wolf <W_Armin@gmx.de>
In-Reply-To: <CAJZ5v0gu=yvFeXH4uwHeAQZ8p1JyCs8uuiKzr6F+yNkD2E1ZAA@mail.gmail.com>
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Am 27.05.24 um 19:29 schrieb Rafael J. Wysocki:

> On Fri, May 10, 2024 at 10:13=E2=80=AFPM Armin Wolf <W_Armin@gmx.de> wro=
te:
>> Currently, the driver does only support a custom sysfs
>> interface to allow userspace to read the fan speed.
>> Add support for the standard hwmon interface so users
>> can read the fan speed with standard tools like "sensors".
>>
>> Reviewed-by: Andy Shevchenko <andy@kernel.org>
>> Signed-off-by: Armin Wolf <W_Armin@gmx.de>
>> ---
>> Tested witha custom ACPI SSDT, available here:
>> https://github.com/Wer-Wolf/acpi-fan-ssdt
>>
>> Changes since v7:
>> - add Reviewed-by tag
>> - spelling fixes
>> - add missing types.h include
>>
>> Changes since v6:
>> - add "hwmon" to the names of functions and variables
>> related to hwmon
>> - replace -ENODATA with -EIO/-ENODEV
>>
>> Changes since v5:
>> - fix coding style issues
>> - replace double break with return
>> - add missing includes
>>
>> Changes since v4:
>> - fix spelling issues
>> - check power values for overflow condition too
>>
>> Changes since v3:
>> - drop fault attrs
>> - rework initialization
>>
>> Changes since v2:
>> - add support for fanX_target and power attrs
>>
>> Changes since v1:
>> - fix undefined reference error
>> - fix fan speed validation
>> - coding style fixes
>> - clarify that the changes are compile-tested only
>> - add hwmon maintainers to cc list
>> ---
>>   drivers/acpi/Makefile    |   1 +
>>   drivers/acpi/fan.h       |   9 +++
>>   drivers/acpi/fan_core.c  |   4 +
>>   drivers/acpi/fan_hwmon.c | 170 ++++++++++++++++++++++++++++++++++++++=
+
>>   4 files changed, 184 insertions(+)
>>   create mode 100644 drivers/acpi/fan_hwmon.c
>>
>> diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
>> index 39ea5cfa8326..61ca4afe83dc 100644
>> --- a/drivers/acpi/Makefile
>> +++ b/drivers/acpi/Makefile
>> @@ -77,6 +77,7 @@ obj-$(CONFIG_ACPI_TINY_POWER_BUTTON)  +=3D tiny-power=
-button.o
>>   obj-$(CONFIG_ACPI_FAN)         +=3D fan.o
>>   fan-objs                       :=3D fan_core.o
>>   fan-objs                       +=3D fan_attr.o
>> +fan-$(CONFIG_HWMON)            +=3D fan_hwmon.o
>>
>>   obj-$(CONFIG_ACPI_VIDEO)       +=3D video.o
>>   obj-$(CONFIG_ACPI_TAD)         +=3D acpi_tad.o
>> diff --git a/drivers/acpi/fan.h b/drivers/acpi/fan.h
>> index f89d19c922dc..db25a3898af7 100644
>> --- a/drivers/acpi/fan.h
>> +++ b/drivers/acpi/fan.h
>> @@ -10,6 +10,8 @@
>>   #ifndef _ACPI_FAN_H_
>>   #define _ACPI_FAN_H_
>>
>> +#include <linux/kconfig.h>
>> +
>>   #define ACPI_FAN_DEVICE_IDS    \
>>          {"INT3404", }, /* Fan */ \
>>          {"INTC1044", }, /* Fan for Tiger Lake generation */ \
>> @@ -57,4 +59,11 @@ struct acpi_fan {
>>   int acpi_fan_get_fst(struct acpi_device *device, struct acpi_fan_fst =
*fst);
>>   int acpi_fan_create_attributes(struct acpi_device *device);
>>   void acpi_fan_delete_attributes(struct acpi_device *device);
>> +
>> +#if IS_REACHABLE(CONFIG_HWMON)
>> +int devm_acpi_fan_create_hwmon(struct acpi_device *device);
>> +#else
>> +static inline int devm_acpi_fan_create_hwmon(struct acpi_device *devic=
e) { return 0; };
>> +#endif
>> +
>>   #endif
>> diff --git a/drivers/acpi/fan_core.c b/drivers/acpi/fan_core.c
>> index ff72e4ef8738..7cea4495f19b 100644
>> --- a/drivers/acpi/fan_core.c
>> +++ b/drivers/acpi/fan_core.c
>> @@ -336,6 +336,10 @@ static int acpi_fan_probe(struct platform_device *=
pdev)
>>                  if (result)
>>                          return result;
>>
>> +               result =3D devm_acpi_fan_create_hwmon(device);
>> +               if (result)
>> +                       return result;
>> +
>>                  result =3D acpi_fan_create_attributes(device);
>>                  if (result)
>>                          return result;
>> diff --git a/drivers/acpi/fan_hwmon.c b/drivers/acpi/fan_hwmon.c
>> new file mode 100644
>> index 000000000000..bd0d31a398fa
>> --- /dev/null
>> +++ b/drivers/acpi/fan_hwmon.c
>> @@ -0,0 +1,170 @@
>> +// SPDX-License-Identifier: GPL-2.0-or-later
>> +/*
>> + * hwmon interface for the ACPI Fan driver.
>> + *
>> + * Copyright (C) 2024 Armin Wolf <W_Armin@gmx.de>
>> + */
>> +
>> +#include <linux/acpi.h>
>> +#include <linux/device.h>
>> +#include <linux/err.h>
>> +#include <linux/hwmon.h>
>> +#include <linux/limits.h>
>> +#include <linux/types.h>
>> +#include <linux/units.h>
>> +
>> +#include "fan.h"
>> +
>> +/* Returned when the ACPI fan does not support speed reporting */
>> +#define FAN_SPEED_UNAVAILABLE  U32_MAX
>> +#define FAN_POWER_UNAVAILABLE  U32_MAX
>> +
>> +static struct acpi_fan_fps *acpi_fan_get_current_fps(struct acpi_fan *=
fan, u64 control)
>> +{
>> +       unsigned int i;
>> +
>> +       for (i =3D 0; i < fan->fps_count; i++) {
>> +               if (fan->fps[i].control =3D=3D control)
>> +                       return &fan->fps[i];
>> +       }
>> +
>> +       return NULL;
>> +}
>> +
>> +static umode_t acpi_fan_hwmon_is_visible(const void *drvdata, enum hwm=
on_sensor_types type,
>> +                                        u32 attr, int channel)
>> +{
>> +       const struct acpi_fan *fan =3D drvdata;
>> +       unsigned int i;
> AFAICS, the code below can be rewritten as follows:
>
> if (fan->fif.fine_grain_ctrl)
>           return 0;

Hi,

this would break hwmon_fan_input.

Thanks,
Armin Wolf

>
> switch (type) {
> case hwmon_fan:
>          if (attr =3D=3D hwmon_fan_input || attr =3D=3D hwmon_fan_target=
)
>                 return 0444;
>
>          return 0;
>
> case hwmon_power:
>          if (attr =3D=3D hwmon_power_input) {
>                 for (i =3D 0; i < fan->fps_count; i++) {
>                         if (fan->fps[i].power !=3D FAN_POWER_UNAVAILABLE=
)
>                                 return 0444;
>                 }
>          }
>
>          fallthrough;
> default:
>         return 0;
> }
>
> without changing functionality, which is both less duplication and
> fewer lines of code.
>
>> +
>> +       switch (type) {
>> +       case hwmon_fan:
>> +               switch (attr) {
>> +               case hwmon_fan_input:
>> +                       return 0444;
>> +               case hwmon_fan_target:
>> +                       /*
>> +                        * When in fine grain control mode, not every f=
an control value
>> +                        * has an associated fan performance state.
>> +                        */
>> +                       if (fan->fif.fine_grain_ctrl)
>> +                               return 0;
>> +
>> +                       return 0444;
>> +               default:
>> +                       return 0;
>> +               }
>> +       case hwmon_power:
>> +               switch (attr) {
>> +               case hwmon_power_input:
>> +                       /*
>> +                        * When in fine grain control mode, not every f=
an control value
>> +                        * has an associated fan performance state.
>> +                        */
>> +                       if (fan->fif.fine_grain_ctrl)
>> +                               return 0;
>> +
>> +                       /*
>> +                        * When all fan performance states contain no v=
alid power data,
>> +                        * when the associated attribute should not be =
created.
>> +                        */
>> +                       for (i =3D 0; i < fan->fps_count; i++) {
>> +                               if (fan->fps[i].power !=3D FAN_POWER_UN=
AVAILABLE)
>> +                                       return 0444;
>> +                       }
>> +
>> +                       return 0;
>> +               default:
>> +                       return 0;
>> +               }
>> +       default:
>> +               return 0;
>> +       }
>> +}
>> +
>> +static int acpi_fan_hwmon_read(struct device *dev, enum hwmon_sensor_t=
ypes type, u32 attr,
>> +                              int channel, long *val)
>> +{
>> +       struct acpi_device *adev =3D to_acpi_device(dev->parent);
>> +       struct acpi_fan *fan =3D dev_get_drvdata(dev);
>> +       struct acpi_fan_fps *fps;
>> +       struct acpi_fan_fst fst;
>> +       int ret;
>> +
>> +       ret =3D acpi_fan_get_fst(adev, &fst);
>> +       if (ret < 0)
>> +               return ret;
>> +
>> +       switch (type) {
>> +       case hwmon_fan:
>> +               switch (attr) {
>> +               case hwmon_fan_input:
>> +                       if (fst.speed =3D=3D FAN_SPEED_UNAVAILABLE)
>> +                               return -ENODEV;
>> +
>> +                       if (fst.speed > LONG_MAX)
>> +                               return -EOVERFLOW;
>> +
>> +                       *val =3D fst.speed;
>> +                       return 0;
>> +               case hwmon_fan_target:
>> +                       fps =3D acpi_fan_get_current_fps(fan, fst.contr=
ol);
>> +                       if (!fps)
>> +                               return -EIO;
>> +
>> +                       if (fps->speed > LONG_MAX)
>> +                               return -EOVERFLOW;
>> +
>> +                       *val =3D fps->speed;
>> +                       return 0;
>> +               default:
>> +                       return -EOPNOTSUPP;
>> +               }
>> +       case hwmon_power:
>> +               switch (attr) {
>> +               case hwmon_power_input:
>> +                       fps =3D acpi_fan_get_current_fps(fan, fst.contr=
ol);
>> +                       if (!fps)
>> +                               return -EIO;
>> +
>> +                       if (fps->power =3D=3D FAN_POWER_UNAVAILABLE)
>> +                               return -ENODEV;
>> +
>> +                       if (fps->power > LONG_MAX / MICROWATT_PER_MILLI=
WATT)
>> +                               return -EOVERFLOW;
>> +
>> +                       *val =3D fps->power * MICROWATT_PER_MILLIWATT;
>> +                       return 0;
>> +               default:
>> +                       return -EOPNOTSUPP;
>> +               }
>> +       default:
>> +               return -EOPNOTSUPP;
>> +       }
>> +}
>> +
>> +static const struct hwmon_ops acpi_fan_hwmon_ops =3D {
>> +       .is_visible =3D acpi_fan_hwmon_is_visible,
>> +       .read =3D acpi_fan_hwmon_read,
>> +};
>> +
>> +static const struct hwmon_channel_info * const acpi_fan_hwmon_info[] =
=3D {
>> +       HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT | HWMON_F_TARGET),
>> +       HWMON_CHANNEL_INFO(power, HWMON_P_INPUT),
>> +       NULL
>> +};
>> +
>> +static const struct hwmon_chip_info acpi_fan_hwmon_chip_info =3D {
>> +       .ops =3D &acpi_fan_hwmon_ops,
>> +       .info =3D acpi_fan_hwmon_info,
>> +};
>> +
>> +int devm_acpi_fan_create_hwmon(struct acpi_device *device)
>> +{
>> +       struct acpi_fan *fan =3D acpi_driver_data(device);
>> +       struct device *hdev;
>> +
>> +       hdev =3D devm_hwmon_device_register_with_info(&device->dev, "ac=
pi_fan", fan,
>> +                                                   &acpi_fan_hwmon_chi=
p_info, NULL);
>> +       return PTR_ERR_OR_ZERO(hdev);
>> +}
>> --
>> 2.39.2
>>
>>