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Message-ID: <d5cf9425-c43d-2771-0906-7c055244d783@linux.intel.com>
Date: Mon, 8 Apr 2024 20:15:17 +0300 (EEST)
From: Ilpo Järvinen <ilpo.jarvinen@...ux.intel.com>
To: Armin Wolf <W_Armin@....de>
cc: mlj@...elec.com, rafael.j.wysocki@...el.com, lenb@...nel.org,
linux-acpi@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH] ACPI: fan: Add hwmon support
On Mon, 8 Apr 2024, Armin Wolf wrote:
> Am 08.04.24 um 17:48 schrieb Ilpo Järvinen:
> > On Mon, 8 Apr 2024, Armin Wolf wrote:
> >
> > > 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".
> > >
> > > Signed-off-by: Armin Wolf <W_Armin@....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
> > >
> > > 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-$(CONFIG_ACPI_TINY_POWER_BUTTON) +=
> > > tiny-power-button.o
> > > obj-$(CONFIG_ACPI_FAN) += fan.o
> > > fan-objs := fan_core.o
> > > fan-objs += fan_attr.o
> > > +fan-objs += fan_hwmon.o
> > >
> > > obj-$(CONFIG_ACPI_VIDEO) += video.o
> > > obj-$(CONFIG_ACPI_TAD) += 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_fst
> > > *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.
> > > */
> > >
> > > +#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)
> > > if (result)
> > > return result;
> > >
> > > + if (IS_REACHABLE(CONFIG_HWMON)) {
> > > + result = devm_acpi_fan_create_hwmon(device);
> > > + if (result)
> > > + return result;
> > > + }
> > > +
> > > result = 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..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@....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,
> > > + int channel)
> > > +{
> > > + return 0444;
> > > +}
> > > +
> > > +static int acpi_fan_read(struct device *dev, enum hwmon_sensor_types
> > > type, u32 attr, int channel,
> > > + long *val)
> > > +{
> > > + struct acpi_device *adev = dev_get_drvdata(dev);
> > > + struct acpi_fan_fst fst;
> > > + int ret;
> > > +
> > > + switch (type) {
> > > + case hwmon_fan:
> > > + ret = acpi_fan_get_fst(adev, &fst);
> > > + if (ret < 0)
> > > + return ret;
> > > +
> > > + switch (attr) {
> > > + case hwmon_fan_input:
> > > + if (fst.speed > LONG_MAX)
> > > + return -EOVERFLOW;
> > > +
> > > + *val = fst.speed;
> > > + return 0;
> > > + case hwmon_fan_fault:
> > > + *val = (fst.speed == U32_MAX);
> > > + return 0;
> > Is it okay to return 0 in this case?
>
> Hi,
>
> 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.
--
i.
> > > + default:
> > > + break;
> > > + }
> > > + break;
> > > + default:
> > > + break;
> > > + }
> > > +
> > > + return -EOPNOTSUPP;
> > > +}
> > > +
> > > +static const struct hwmon_ops acpi_fan_ops = {
> > > + .is_visible = acpi_fan_is_visible,
> > > + .read = acpi_fan_read,
> > > +};
> > > +
> > > +static const struct hwmon_channel_info * const acpi_fan_info[] = {
> > > + HWMON_CHANNEL_INFO(fan,
> > > + HWMON_F_INPUT | HWMON_F_FAULT),
> > One line.
> >
>
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