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Date: Fri, 12 Apr 2024 22:27:56 +0200
From: Armin Wolf <W_Armin@....de>
To: Guenter Roeck <linux@...ck-us.net>
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
Am 12.04.24 um 18:41 schrieb Guenter Roeck:
> 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) ?
>
Hi,
it actually means that the fan does not support speed reporting.
>> + 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
>
FAN_POWER_UNAVAILABLE signals that the power value is not supported.
Would it be more suitable to drop the fault attributes and just return -ENODATA in such a case?
Thanks,
Armin Wolf
>> + 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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