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From: =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Date: Mon, 8 Apr 2024 20:15:17 +0300 (EEST)
To: Armin Wolf <W_Armin@gmx.de>
cc: mlj@danelec.com, rafael.j.wysocki@intel.com, lenb@kernel.org, 
    linux-acpi@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>, 
    platform-driver-x86@vger.kernel.org
Subject: Re: [PATCH] ACPI: fan: Add hwmon support
In-Reply-To: <36a8ebff-8a89-44e0-9b30-374913bd8cbd@gmx.de>
Message-ID: <d5cf9425-c43d-2771-0906-7c055244d783@linux.intel.com>
References: <20240408123718.15512-1-W_Armin@gmx.de> <63187b48-7978-3b0f-0526-79afea65c492@linux.intel.com> <36a8ebff-8a89-44e0-9b30-374913bd8cbd@gmx.de>
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On Mon, 8 Apr 2024, Armin Wolf wrote:
> Am 08.04.24 um 17:48 schrieb Ilpo J=C3=A4rvinen:
> > On Mon, 8 Apr 2024, Armin Wolf wrote:
> >=20
> > > Currently, the driver does only supports 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".
> > >=20
> > > Signed-off-by: Armin Wolf <W_Armin@gmx.de>
> > > ---
> > >   drivers/acpi/Makefile    |  1 +
> > >   drivers/acpi/fan.h       |  2 ++
> > >   drivers/acpi/fan_core.c  |  7 ++++
> > >   drivers/acpi/fan_hwmon.c | 78 +++++++++++++++++++++++++++++++++++++=
+++
> > >   4 files changed, 88 insertions(+)
> > >   create mode 100644 drivers/acpi/fan_hwmon.c
> > >=20
> > > diff --git a/drivers/acpi/Makefile b/drivers/acpi/Makefile
> > > index d69d5444acdb..9a2e03acc1be 100644
> > > --- a/drivers/acpi/Makefile
> > > +++ b/drivers/acpi/Makefile
> > > @@ -83,6 +83,7 @@ obj-$(CONFIG_ACPI_TINY_POWER_BUTTON)=09+=3D
> > > tiny-power-button.o
> > >   obj-$(CONFIG_ACPI_FAN)=09=09+=3D fan.o
> > >   fan-objs=09=09=09:=3D fan_core.o
> > >   fan-objs=09=09=09+=3D fan_attr.o
> > > +fan-objs=09=09=09+=3D fan_hwmon.o
> > >=20
> > >   obj-$(CONFIG_ACPI_VIDEO)=09+=3D video.o
> > >   obj-$(CONFIG_ACPI_TAD)=09=09+=3D acpi_tad.o
> > > diff --git a/drivers/acpi/fan.h b/drivers/acpi/fan.h
> > > index e7b4b4e4a55e..45c2637566da 100644
> > > --- a/drivers/acpi/fan.h
> > > +++ b/drivers/acpi/fan.h
> > > @@ -56,4 +56,6 @@ struct acpi_fan {
> > >   int acpi_fan_get_fst(struct acpi_device *device, struct acpi_fan_fs=
t
> > > *fst);
> > >   int acpi_fan_create_attributes(struct acpi_device *device);
> > >   void acpi_fan_delete_attributes(struct acpi_device *device);
> > > +
> > > +int devm_acpi_fan_create_hwmon(struct acpi_device *device);
> > >   #endif
> > > diff --git a/drivers/acpi/fan_core.c b/drivers/acpi/fan_core.c
> > > index ff72e4ef8738..6bbdbb914e95 100644
> > > --- a/drivers/acpi/fan_core.c
> > > +++ b/drivers/acpi/fan_core.c
> > > @@ -7,6 +7,7 @@
> > >    *  Copyright (C) 2022 Intel Corporation. All rights reserved.
> > >    */
> > >=20
> > > +#include <linux/kconfig.h>
> > >   #include <linux/kernel.h>
> > >   #include <linux/module.h>
> > >   #include <linux/init.h>
> > > @@ -336,6 +337,12 @@ static int acpi_fan_probe(struct platform_device
> > > *pdev)
> > >   =09=09if (result)
> > >   =09=09=09return result;
> > >=20
> > > +=09=09if (IS_REACHABLE(CONFIG_HWMON)) {
> > > +=09=09=09result =3D devm_acpi_fan_create_hwmon(device);
> > > +=09=09=09if (result)
> > > +=09=09=09=09return result;
> > > +=09=09}
> > > +
> > >   =09=09result =3D acpi_fan_create_attributes(device);
> > >   =09=09if (result)
> > >   =09=09=09return result;
> > > diff --git a/drivers/acpi/fan_hwmon.c b/drivers/acpi/fan_hwmon.c
> > > new file mode 100644
> > > index 000000000000..4f2bec8664f4
> > > --- /dev/null
> > > +++ b/drivers/acpi/fan_hwmon.c
> > > @@ -0,0 +1,78 @@
> > > +// SPDX-License-Identifier: GPL-2.0-or-later
> > > +/*
> > > + * fan_hwmon.c - hwmon interface for the ACPI Fan driver
> > > + *
> > > + * Copyright (C) 2024 Armin Wolf <W_Armin@gmx.de>
> > > + */
> > > +
> > > +#include <linux/acpi.h>
> > > +#include <linux/hwmon.h>
> > > +#include <linux/limits.h>
> > > +
> > > +#include "fan.h"
> > > +
> > > +static umode_t acpi_fan_is_visible(const void *drvdata, enum
> > > hwmon_sensor_types type, u32 attr,
> > > +=09=09=09=09   int channel)
> > > +{
> > > +=09return 0444;
> > > +}
> > > +
> > > +static int acpi_fan_read(struct device *dev, enum hwmon_sensor_types
> > > type, u32 attr, int channel,
> > > +=09=09=09 long *val)
> > > +{
> > > +=09struct acpi_device *adev =3D dev_get_drvdata(dev);
> > > +=09struct acpi_fan_fst fst;
> > > +=09int ret;
> > > +
> > > +=09switch (type) {
> > > +=09case hwmon_fan:
> > > +=09=09ret =3D acpi_fan_get_fst(adev, &fst);
> > > +=09=09if (ret < 0)
> > > +=09=09=09return ret;
> > > +
> > > +=09=09switch (attr) {
> > > +=09=09case hwmon_fan_input:
> > > +=09=09=09if (fst.speed > LONG_MAX)
> > > +=09=09=09=09return -EOVERFLOW;
> > > +
> > > +=09=09=09*val =3D fst.speed;
> > > +=09=09=09return 0;
> > > +=09=09case hwmon_fan_fault:
> > > +=09=09=09*val =3D (fst.speed =3D=3D U32_MAX);
> > > +=09=09=09return 0;
> > Is it okay to return 0 in this case?
>=20
> Hi,
>=20
> i think so, since the value of the attribute (with the meaning of "is the=
 rpm
> value ok?") is being
> correctly stored in val. If acpi_fan_get_fst() fails, we already return a
> negative error code.

Ah, right. It seems fine.

--=20
 i.

> > > +=09=09default:
> > > +=09=09=09break;
> > > +=09=09}
> > > +=09=09break;
> > > +=09default:
> > > +=09=09break;
> > > +=09}
> > > +
> > > +=09return -EOPNOTSUPP;
> > > +}
> > > +
> > > +static const struct hwmon_ops acpi_fan_ops =3D {
> > > +=09.is_visible =3D acpi_fan_is_visible,
> > > +=09.read =3D acpi_fan_read,
> > > +};
> > > +
> > > +static const struct hwmon_channel_info * const acpi_fan_info[] =3D {
> > > +=09HWMON_CHANNEL_INFO(fan,
> > > +=09=09=09   HWMON_F_INPUT | HWMON_F_FAULT),
> > One line.
> >=20
>=20

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