linux-kernel - Re: [PATCH v8 1/2] hwmon: add GPD devices sensor driver

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Message-ID: <c6694917-fbfd-432d-ab17-f5f9b7232e7c@roeck-us.net>
Date: Sat, 6 Sep 2025 07:06:18 -0700
From: Guenter Roeck <linux@...ck-us.net>
To: cryolitia@...ontech.com, Jean Delvare <jdelvare@...e.com>,
 Jonathan Corbet <corbet@....net>
Cc: linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org,
 linux-doc@...r.kernel.org, Celeste Liu <CoelacanthusHex@...il.com>,
 Yao Zi <ziyao@...root.org>, Derek John Clark <derekjohn.clark@...il.com>,
 Jun Zhan <zhanjun@...ontech.com>, Cheng Nie <niecheng1@...ontech.com>,
 Marcin Strągowski <marcin@...agowski.com>,
 someone5678 <someone5678.dev@...il.com>,
 Justin Weiss <justin@...tinweiss.com>, Antheas Kapenekakis
 <lkml@...heas.dev>, command_block <mtf@...me>, derjohn <himself@...john.de>,
 Crashdummyy <crashdummy1337@...ton.me>
Subject: Re: [PATCH v8 1/2] hwmon: add GPD devices sensor driver

On 9/4/25 01:33, Cryolitia PukNgae via B4 Relay wrote:
> From: Cryolitia PukNgae <cryolitia@...ontech.com>
> 
> Sensors driver for GPD Handhelds that expose fan reading and control via
> hwmon sysfs.
> 
> Shenzhen GPD Technology Co., Ltd. manufactures a series of handheld
> devices. This driver implements these functions through x86 port-mapped
> IO.
> 
> Tested-by: Marcin Strągowski <marcin@...agowski.com>
> Tested-by: someone5678 <someone5678.dev@...il.com>
> Tested-by: Justin Weiss <justin@...tinweiss.com>
> Tested-by: Antheas Kapenekakis <lkml@...heas.dev>
> Tested-by: command_block <mtf@...me>
> Tested-by: derjohn <himself@...john.de>
> Tested-by: Crashdummyy <crashdummy1337@...ton.me>
> Signed-off-by: Cryolitia PukNgae <cryolitia@...ontech.com>
> ---
>   MAINTAINERS             |   6 +
>   drivers/hwmon/Kconfig   |  10 +
>   drivers/hwmon/Makefile  |   1 +
>   drivers/hwmon/gpd-fan.c | 786 ++++++++++++++++++++++++++++++++++++++++++++++++
>   4 files changed, 803 insertions(+)
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index 6dcfbd11efef87927041f5cf58d70633dbb4b18d..14a616be5ff08aaeee52436dff54a86c4a81e5fb 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -10421,6 +10421,12 @@ F:	drivers/phy/samsung/phy-gs101-ufs.c
>   F:	include/dt-bindings/clock/google,gs101.h
>   K:	[gG]oogle.?[tT]ensor
>   
> +GPD FAN DRIVER
> +M:	Cryolitia PukNgae <cryolitia@...ontech.com>
> +L:	linux-hwmon@...r.kernel.org
> +S:	Maintained
> +F:	drivers/hwmon/gpd-fan.c
> +
>   GPD POCKET FAN DRIVER
>   M:	Hans de Goede <hansg@...nel.org>
>   L:	platform-driver-x86@...r.kernel.org
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 9d28fcf7cd2a6f9e2f54694a717bd85ff4047b46..a552a5ced64d0fee2c80a5399ce9d1f0dbd7d763 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -769,6 +769,16 @@ config SENSORS_GL520SM
>   	  This driver can also be built as a module. If so, the module
>   	  will be called gl520sm.
>   
> +config SENSORS_GPD
> +	tristate "GPD handhelds"
> +	depends on X86
> +	help
> +	  If you say yes here you get support for fan readings and
> +	  control over GPD handheld devices.
> +
> +	  Can also be built as a module. In that case it will be
> +	  called gpd-fan.
> +
>   config SENSORS_G760A
>   	tristate "GMT G760A"
>   	depends on I2C
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index cd8bc4752b4dbf015c6eb46157626f4e8f87dfae..051981eb8a5089608e9eb351a1d5857805c728c8 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -88,6 +88,7 @@ obj-$(CONFIG_SENSORS_GIGABYTE_WATERFORCE) += gigabyte_waterforce.o
>   obj-$(CONFIG_SENSORS_GL518SM)	+= gl518sm.o
>   obj-$(CONFIG_SENSORS_GL520SM)	+= gl520sm.o
>   obj-$(CONFIG_SENSORS_GSC)	+= gsc-hwmon.o
> +obj-$(CONFIG_SENSORS_GPD)	+= gpd-fan.o
>   obj-$(CONFIG_SENSORS_GPIO_FAN)	+= gpio-fan.o
>   obj-$(CONFIG_SENSORS_GXP_FAN_CTRL) += gxp-fan-ctrl.o
>   obj-$(CONFIG_SENSORS_HIH6130)	+= hih6130.o
> diff --git a/drivers/hwmon/gpd-fan.c b/drivers/hwmon/gpd-fan.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..4a9ae049a78524caa0fd608c119eb34c333429ae
> --- /dev/null
> +++ b/drivers/hwmon/gpd-fan.c
> @@ -0,0 +1,786 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +
> +/* Platform driver for GPD devices that expose fan control via hwmon sysfs.
> + *
> + * Fan control is provided via pwm interface in the range [0-255].
> + * Each model has a different range in the EC, the written value is scaled to
> + * accommodate for that.
> + *
> + * Based on this repo:
> + * https://github.com/Cryolitia/gpd-fan-driver
> + *
> + * Copyright (c) 2024 Cryolitia PukNgae
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/dmi.h>
> +#include <linux/hwmon.h>
> +#include <linux/ioport.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +
> +#define DRIVER_NAME "gpdfan"
> +#define GPD_PWM_CTR_OFFSET 0x1841
> +
> +static char *gpd_fan_board = "";
> +module_param(gpd_fan_board, charp, 0444);
> +
> +// EC read/write locker, protecting single EC access
> +// Should never access EC at the same time, otherwise system down.
> +static DEFINE_MUTEX(gpd_fan_atomic_lock);

Why keep this lock ? Each access sequence is now locked in the top
level read/write function, which should make this lock redundant.

Guenter