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Message-ID: <4a07f4d1-bbee-445c-a7cc-377506de850d@roeck-us.net>
Date: Fri, 12 Apr 2024 09:41:08 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: Armin Wolf <W_Armin@....de>
Cc: mlj@...elec.com, rafael.j.wysocki@...el.com, lenb@...nel.org,
jdelvare@...e.com, linux@...ssschuh.net,
ilpo.jarvinen@...ux.intel.com, linux-acpi@...r.kernel.org,
linux-hwmon@...r.kernel.org, linux-kernel@...r.kernel.org,
platform-driver-x86@...r.kernel.org
Subject: Re: [PATCH v3 2/2] ACPI: fan: Add hwmon support
On Fri, Apr 12, 2024 at 06:08:57PM +0200, Armin Wolf wrote:
> Currently, the driver does only support a custom sysfs
> 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".
>
> Compile-tested only.
>
> Signed-off-by: Armin Wolf <W_Armin@....de>
> ---
> 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
>
> The changes will be tested by Mikael Lund Jepsen from Danelec and
> should be merged only after those tests.
> ---
> drivers/acpi/Makefile | 1 +
> drivers/acpi/fan.h | 9 +++
> drivers/acpi/fan_core.c | 4 ++
> drivers/acpi/fan_hwmon.c | 148 +++++++++++++++++++++++++++++++++++++++
> 4 files changed, 162 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-$(CONFIG_ACPI_TINY_POWER_BUTTON) += tiny-power-button.o
> obj-$(CONFIG_ACPI_FAN) += fan.o
> fan-objs := fan_core.o
> fan-objs += fan_attr.o
> +fan-$(CONFIG_HWMON) += fan_hwmon.o
>
> obj-$(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 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 *device) { 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 = 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..57216ba872db
> --- /dev/null
> +++ b/drivers/acpi/fan_hwmon.c
> @@ -0,0 +1,148 @@
> +// 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 <linux/units.h>
> +
> +#include "fan.h"
> +
> +/* Returned when the ACPI fan does not support speed reporting */
> +#define FAN_SPEED_UNAVAILABLE 0xffffffff
> +#define FAN_POWER_UNAVAILABLE 0xffffffff
> +
> +static struct acpi_fan_fps *acpi_fan_get_current_fps(struct acpi_fan *fan, u64 control)
> +{
> + int i;
> +
> + for (i = 0; i < fan->fps_count; i++) {
> + if (fan->fps[i].control == control)
> + return &fan->fps[i];
> + }
> +
> + return NULL;
> +}
> +
> +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 *fan = acpi_driver_data(adev);
> + struct acpi_fan_fps *fps;
> + struct acpi_fan_fst fst;
> + int ret;
> +
> + ret = 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 == FAN_SPEED_UNAVAILABLE)
> + return -ENODATA;
> +
> + if (fst.speed > LONG_MAX)
> + return -EOVERFLOW;
> +
> + *val = fst.speed;
> + return 0;
> + case hwmon_fan_target:
> + fps = acpi_fan_get_current_fps(fan, fst.control);
> + if (!fps)
> + return -ENODATA;
> +
> + *val = fps->speed;
> + return 0;
> + case hwmon_fan_fault:
> + *val = (fst.speed == FAN_SPEED_UNAVAILABLE);
Is it documented that this is indeed a fault (broken fan) ?
> + return 0;
> + default:
> + break;
> + }
> + break;
> + case hwmon_power:
> + fps = acpi_fan_get_current_fps(fan, fst.control);
> + if (!fps)
> + return -ENODATA;
> +
> + switch (attr) {
> + case hwmon_power_input:
> + if (fps->power == FAN_POWER_UNAVAILABLE)
> + return -ENODATA;
> +
> + if (fps->power > LONG_MAX / MICROWATT_PER_MILLIWATT)
> + return -EOVERFLOW;
> +
> + *val = fps->power * MICROWATT_PER_MILLIWATT;
> + return 0;
> + case hwmon_power_fault:
> + *val = (fps->power == FAN_POWER_UNAVAILABLE);
Is it documented that this is indeed a power supply failure ?
What if the value is simply not reported ? "UNAVAILABLE" is not
commonly associated with a "fault".
Guenter
> + return 0;
> + 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_TARGET | HWMON_F_FAULT),
> + HWMON_CHANNEL_INFO(power, HWMON_P_INPUT | HWMON_P_FAULT),
> + NULL
> +};
> +
> +static const struct hwmon_chip_info acpi_fan_chip_info = {
> + .ops = &acpi_fan_ops,
> + .info = acpi_fan_info,
> +};
> +
> +static const struct hwmon_channel_info * const acpi_fan_fine_grain_info[] = {
> + HWMON_CHANNEL_INFO(fan, HWMON_F_INPUT | HWMON_F_FAULT),
> + NULL
> +};
> +
> +static const struct hwmon_chip_info acpi_fan_fine_grain_chip_info = {
> + .ops = &acpi_fan_ops,
> + .info = acpi_fan_fine_grain_info,
> +};
> +
> +int devm_acpi_fan_create_hwmon(struct acpi_device *device)
> +{
> + struct acpi_fan *fan = acpi_driver_data(device);
> + const struct hwmon_chip_info *info;
> + struct device *hdev;
> +
> + /* When in fine grain control mode, not every fan control value
> + * has an associated fan performance state.
> + */
> + if (fan->fif.fine_grain_ctrl)
> + info = &acpi_fan_fine_grain_chip_info;
> + else
> + info = &acpi_fan_chip_info;
> +
> + hdev = devm_hwmon_device_register_with_info(&device->dev, "acpi_fan", device, info, NULL);
> +
> + return PTR_ERR_OR_ZERO(hdev);
> +}
> --
> 2.39.2
>
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