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Date: Wed, 24 Apr 2024 23:53:08 +0200
From: Armin Wolf <W_Armin@....de>
To: Guenter Roeck <linux@...ck-us.net>, "Rafael J. Wysocki"
<rafael@...nel.org>
Cc: mlj@...elec.com, rafael.j.wysocki@...el.com, lenb@...nel.org,
jdelvare@...e.com, andy.shevchenko@...il.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 v6] ACPI: fan: Add hwmon support
Am 24.04.24 um 21:42 schrieb Guenter Roeck:
> On 4/24/24 12:01, Rafael J. Wysocki wrote:
>> On Mon, Apr 22, 2024 at 9:58 PM Armin Wolf <W_Armin@....de> wrote:
>>>
>>> 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".
>>>
>>> Tested with a custom ACPI SSDT.
>>>
>>> Signed-off-by: Armin Wolf <W_Armin@....de>
>>
>> I need Guenter to tell me that this is fine with him.
>>
>
> Sorry, I have no idea. Se below.
>
>> Also please see one nit below.
>>
>>> ---
>>> 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 | 169
>>> +++++++++++++++++++++++++++++++++++++++
>>> 4 files changed, 183 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..34a524c285a5
>>> --- /dev/null
>>> +++ b/drivers/acpi/fan_hwmon.c
>>> @@ -0,0 +1,169 @@
>>> +// SPDX-License-Identifier: GPL-2.0-or-later
>>> +/*
>>> + * Hwmon interface for the ACPI Fan driver.
>>> + *
>>> + * Copyright (C) 2024 Armin Wolf <W_Armin@....de>
>>> + */
>>> +
>>> +#include <linux/acpi.h>
>>> +#include <linux/device.h>
>>> +#include <linux/err.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 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 = 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)
>>> +{
>>> + const struct acpi_fan *fan = drvdata;
>>> + unsigned int i;
>>> +
>>> + 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 fan 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 fan control value
>>> + * has an associated fan performance state.
>>> + */
>>> + if (fan->fif.fine_grain_ctrl)
>>> + return 0;
>>> +
>>> + /*
>>> + * When all fan performance states contain
>>> no valid power data,
>>> + * when the associated attribute should not
>>> be created.
>>> + */
>>> + for (i = 0; i < fan->fps_count; i++) {
>>> + if (fan->fps[i].power !=
>>> FAN_POWER_UNAVAILABLE)
>>> + return 0444;
>>> + }
>
> Is this all or nothing ? Doesn't this depend on the channel ? It looks
> as if the first fan supports reporting the power, attributes are
> generated for all fans even if the others don't support it
Hi,
those fps entries are different performance states for a single fan, see ACPI spec 11.3.1.2
(link: https://uefi.org/specs/ACPI/6.5/11_Thermal_Management.html#fan-device).
The code basically checks that if at least one performance state contains valid power data,
the powerX_input attribute is created.
>
> To me it looks like there are situations where individual
> fans will still persistently report -ENODATA for fan speed, power,
> or both. I don't know the specification well enough (not at all, really)
> to be able to determine if this makes sense. Normally, -ENODATA should be
> reserved for "value temporarily not available". I am not sure if that is
> the case here.
>
> Guenter
>
The power attributes will not be created if all performance states contain no valid
power values, so -ENODATA will only be returned if the current performance state contains
no valid power data (unlikely to happen, all firmware implementations i have seen either
contain valid power values for all performance states or none at all).
The fan attributes are a bit different, as FAN_SPEED_UNAVAILABLE can either signal that
fan speed reporting is not supported _or_ that reading of the fan speed failed, so we cannot
check if FAN_SPEED_UNAVAILABLE was returned due to a temporary error or due to missing support.
Thanks,
Armin Wolf
>>> +
>>> + return 0;
>>> + default:
>>> + return 0;
>>> + }
>>> + default:
>>> + return 0;
>>> + }
>>> +}
>>> +
>>> +static int acpi_fan_read(struct device *dev, enum
>>> hwmon_sensor_types type, u32 attr, int channel,
>>> + long *val)
>>> +{
>>> + struct acpi_device *adev = to_acpi_device(dev->parent);
>>> + struct acpi_fan *fan = dev_get_drvdata(dev);
>>> + 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;
>>> +
>>> + if (fps->speed > LONG_MAX)
>>> + return -EOVERFLOW;
>>> +
>>> + *val = fps->speed;
>>> + return 0;
>>> + default:
>>> + return -EOPNOTSUPP;
>>> + }
>>> + case hwmon_power:
>>> + switch (attr) {
>>> + case hwmon_power_input:
>>> + fps = acpi_fan_get_current_fps(fan,
>>> fst.control);
>>> + if (!fps)
>>> + return -ENODATA;
>>> +
>>> + 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;
>>> + default:
>>> + return -EOPNOTSUPP;
>>> + }
>>> + default:
>>> + return -EOPNOTSUPP;
>>> + }
>>> +}
>>> +
>>> +static const struct hwmon_ops acpi_fan_ops = {
>>> + .is_visible = acpi_fan_is_visible,
>>> + .read = acpi_fan_read,
>>> +};
>>
>> I would add "hwmon" to the names of functions and variables related to
>> hwmon. Something like
>>
>> +static const struct hwmon_ops acpi_fan_hwmon_ops = {
>> + .is_visible = acpi_fan_hwmon_is_visible,
>> + .read = acpi_fan_hwmon_read,
>> +};
>>
>> Otherwise, it looks fine to me.
>>
>>> +
>>> +static const struct hwmon_channel_info * const acpi_fan_info[] = {
>>> + 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_chip_info = {
>>> + .ops = &acpi_fan_ops,
>>> + .info = acpi_fan_info,
>>> +};
>>> +
>>> +int devm_acpi_fan_create_hwmon(struct acpi_device *device)
>>> +{
>>> + struct acpi_fan *fan = acpi_driver_data(device);
>>> + struct device *hdev;
>>> +
>>> + hdev = devm_hwmon_device_register_with_info(&device->dev,
>>> "acpi_fan", fan,
>>> + &acpi_fan_chip_info, NULL);
>>> + return PTR_ERR_OR_ZERO(hdev);
>>> +}
>>> --
>
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