Date:   Wed, 07 Apr 2021 18:27:44 +0000
From:   Barnabás Pőcze <pobrn@...tonmail.com>
To:     Thomas Weißschuh <linux@...ssschuh.net>
Cc:     "platform-driver-x86@...r.kernel.org" 
        <platform-driver-x86@...r.kernel.org>,
        Mark Gross <mgross@...ux.intel.com>,
        Hans de Goede <hdegoede@...hat.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Matthew Garrett <mjg59@...f.ucam.org>
Subject: Re: [PATCH v2] platform/x86: add Gigabyte WMI temperature driver

Hi


2021. április 5., hétfő 22:48 keltezéssel, Thomas Weißschuh írta:

> Changes since v1:
> * Incorporate feedback from Barnabás Pőcze
>   * Use a WMI driver instead of a platform driver
>   * Let the kernel manage the driver lifecycle
>   * Fix errno/ACPI error confusion
>   * Fix resource cleanup
>   * Document reason for integer casting
>
> Thank you Barnabás for your review, it is much appreciated.
>
> -- >8 --
>
> Tested with a X570 I Aorus Pro Wifi.
> The mainboard contains an ITE IT8688E chip for management.
> This chips is also handled by drivers/hwmon/i87.c but as it is also used
> by the firmware itself it needs an ACPI driver.

I gather this means you're getting the

  ACPI Warning: SystemIO range ... conflicts with ...
  ACPI: If an ACPI driver is available for this device, you should use it instead of the native driver

warning?


>
> Unfortunately not all sensor registers are handled by the firmware and even
> less are exposed via WMI.
>
> Signed-off-by: Thomas Weißschuh <linux@...ssschuh.net>
> ---
>  drivers/platform/x86/Kconfig        |  11 +++
>  drivers/platform/x86/Makefile       |   1 +
>  drivers/platform/x86/gigabyte-wmi.c | 138 ++++++++++++++++++++++++++++
>  3 files changed, 150 insertions(+)
>  create mode 100644 drivers/platform/x86/gigabyte-wmi.c
>
> diff --git a/drivers/platform/x86/Kconfig b/drivers/platform/x86/Kconfig
> index ad4e630e73e2..96622a2106f7 100644
> --- a/drivers/platform/x86/Kconfig
> +++ b/drivers/platform/x86/Kconfig
> @@ -123,6 +123,17 @@ config XIAOMI_WMI
>  	  To compile this driver as a module, choose M here: the module will
>  	  be called xiaomi-wmi.
>
> +config GIGABYTE_WMI
> +	tristate "Gigabyte WMI temperature driver"
> +	depends on ACPI_WMI
> +	depends on HWMON
> +	help
> +	  Say Y here if you want to support WMI-based temperature reporting on
> +	  Gigabyte mainboards.
> +
> +	  To compile this driver as a module, choose M here: the module will
> +	  be called gigabyte-wmi.
> +
>  config ACERHDF
>  	tristate "Acer Aspire One temperature and fan driver"
>  	depends on ACPI && THERMAL
> diff --git a/drivers/platform/x86/Makefile b/drivers/platform/x86/Makefile
> index 60d554073749..1621ebfd04fd 100644
> --- a/drivers/platform/x86/Makefile
> +++ b/drivers/platform/x86/Makefile
> @@ -15,6 +15,7 @@ obj-$(CONFIG_INTEL_WMI_THUNDERBOLT)	+= intel-wmi-thunderbolt.o
>  obj-$(CONFIG_MXM_WMI)			+= mxm-wmi.o
>  obj-$(CONFIG_PEAQ_WMI)			+= peaq-wmi.o
>  obj-$(CONFIG_XIAOMI_WMI)		+= xiaomi-wmi.o
> +obj-$(CONFIG_GIGABYTE_WMI)		+= gigabyte-wmi.o
>
>  # Acer
>  obj-$(CONFIG_ACERHDF)		+= acerhdf.o
> diff --git a/drivers/platform/x86/gigabyte-wmi.c b/drivers/platform/x86/gigabyte-wmi.c
> new file mode 100644
> index 000000000000..8618363e3ccf
> --- /dev/null
> +++ b/drivers/platform/x86/gigabyte-wmi.c
> @@ -0,0 +1,138 @@
> +// SPDX-License-Identifier: GPL-2.0-or-later
> +/*
> + *  Copyright (C) 2021 Thomas Weißschuh <thomas@...ssschuh.net>
> + */
> +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
> +
> +#include <linux/acpi.h>
> +#include <linux/hwmon.h>
> +#include <linux/module.h>
> +#include <linux/wmi.h>
> +
> +#define GIGABYTE_WMI_GUID "DEADBEEF-2001-0000-00A0-C90629100000"
> +
> +enum gigabyte_wmi_commandtype {
> +	GIGABYTE_WMI_BUILD_DATE_QUERY       =   0x1,
> +	GIGABYTE_WMI_MAINBOARD_TYPE_QUERY   =   0x2,
> +	GIGABYTE_WMI_FIRMWARE_VERSION_QUERY =   0x4,
> +	GIGABYTE_WMI_MAINBOARD_NAME_QUERY   =   0x5,
> +	GIGABYTE_WMI_TEMPERATURE_QUERY      = 0x125,
> +};
> +
> +struct gigabyte_wmi_args {
> +	u32 arg1;
> +};
> +
> +static int gigabyte_wmi_perform_query(enum gigabyte_wmi_commandtype command,
> +		struct gigabyte_wmi_args *args, struct acpi_buffer *out)
> +{
> +	const struct acpi_buffer in = {
> +		.length = sizeof(*args),
> +		.pointer = args,
> +	};
> +
> +	acpi_status ret = wmi_evaluate_method(GIGABYTE_WMI_GUID, 0x0, command, &in, out);

Ideally, you'd use the WMI device that was passed to the probe method to do the query
using `wmidev_evaluate_method()`. You can pass the WMI device pointer
to `devm_hwmon_device_register_with_info()` in the `drvdata` argument,
then in the ->read() callback you can retrieve it:

  static int gigabyte_wmi_hwmon_read(struct device *dev, ...)
  {
    struct wmi_device *wdev = dev_get_drvdata(dev);

and then you can pass that to the other functions.


> +	if (ret == AE_OK) {
> +		return 0;
> +	} else {
> +		return -EIO;
> +	};

The `;` is not needed. And please use `ACPI_FAILURE()` or `ACPI_SUCCESS()`
to check the returned value. For example:

  acpi_status ret = ...;
  if (ACPI_FAILURE(ret))
    return -EIO;

  return 0;


> +}
> +
> +static int gigabyte_wmi_query_integer(enum gigabyte_wmi_commandtype command,
> +		struct gigabyte_wmi_args *args, u64 *res)
> +{
> +	union acpi_object *obj;
> +	struct acpi_buffer result = { ACPI_ALLOCATE_BUFFER, NULL };
> +	int ret;
> +
> +	ret = gigabyte_wmi_perform_query(command, args, &result);
> +	if (ret) {
> +		goto out;

I believe if this branch is taken, no buffer is allocated (due to the failure),
so you can just `return ret;` here and do away with the goto completely - if I'm not mistaken.


> +	}
> +	obj = result.pointer;
> +	if (obj && obj->type == ACPI_TYPE_INTEGER) {
> +		*res = obj->integer.value;
> +		ret = 0;
> +	} else {
> +		ret = -EIO;
> +	}
> +out:
> +	kfree(result.pointer);
> +	return ret;
> +}
> +
> +static int gigabyte_wmi_temperature(u8 sensor, long *res)
> +{
> +	struct gigabyte_wmi_args args = {
> +		.arg1 = sensor,
> +	};
> +	u64 temp;
> +	acpi_status ret;
> +
> +	ret = gigabyte_wmi_query_integer(GIGABYTE_WMI_TEMPERATURE_QUERY, &args, &temp);
> +	if (ret == 0)
> +		*res = (s8) temp * 1000; // value is a signed 8-bit integer
> +	return ret;
> +}
> +
> +static int gigabyte_wmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> +		u32 attr, int channel, long *val)
> +{
> +	return gigabyte_wmi_temperature(channel, val);
> +}
> +
> +static umode_t gigabyte_wmi_hwmon_is_visible(const void *data, enum hwmon_sensor_types type,
> +		u32 attr, int channel)
> +{
> +	return 0444;
> +}
> +
> +static const struct hwmon_channel_info *gigabyte_wmi_hwmon_info[] = {
> +	HWMON_CHANNEL_INFO(temp,
> +			HWMON_T_INPUT,
> +			HWMON_T_INPUT,
> +			HWMON_T_INPUT,
> +			HWMON_T_INPUT,
> +			HWMON_T_INPUT,
> +			HWMON_T_INPUT),
> +	NULL,
            ^
Minor thing: usually commas after sentinel values are omitted.


> +};
> +
> +static const struct hwmon_ops gigabyte_wmi_hwmon_ops = {
> +	.read = gigabyte_wmi_hwmon_read,
> +	.is_visible = gigabyte_wmi_hwmon_is_visible,
> +};
> +
> +static const struct hwmon_chip_info gigabyte_wmi_hwmon_chip_info = {
> +	.ops = &gigabyte_wmi_hwmon_ops,
> +	.info = gigabyte_wmi_hwmon_info,
> +};
> +
> +static int gigabyte_wmi_probe(struct wmi_device *wdev, const void *context)
> +{
> +	struct device *hwmon_dev = devm_hwmon_device_register_with_info(&wdev->dev,
> +			"gigabyte_wmi", NULL,
> +			&gigabyte_wmi_hwmon_chip_info, NULL);
> +
> +	return PTR_ERR_OR_ZERO(hwmon_dev);
> +}
> +
> +static const struct wmi_device_id gigabyte_wmi_id_table[] = {
> +	{ GIGABYTE_WMI_GUID, NULL },
> +	{ },
           ^
Same here.


> +};
> +
> +static struct wmi_driver gigabyte_wmi_driver = {
> +	.driver = {
> +		.name = "gigabyte-wmi",
> +	},
> +	.id_table = gigabyte_wmi_id_table,
> +	.probe = gigabyte_wmi_probe,
> +};
> +module_wmi_driver(gigabyte_wmi_driver);
> +
> +MODULE_DEVICE_TABLE(wmi, gigabyte_wmi_id_table);
> +MODULE_AUTHOR("Thomas Weißschuh <thomas@...ssschuh.net>");
> +MODULE_DESCRIPTION("Gigabyte Temperature WMI Driver");

It's a very minor thing, but could you please
synchronize this description with the Kconfig?


> +MODULE_LICENSE("GPL");
>
> base-commit: 144c79ef33536b4ecb4951e07dbc1f2b7fa99d32
> --
> 2.31.1


Regards,
Barnabás Pőcze

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