Message-ID: <99f02fd4-2576-efea-295d-9ca264d40a3f@roeck-us.net>
Date:   Mon, 11 Oct 2021 13:29:35 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Denis Pauk <pauk.denis@...il.com>
Cc:     eugene.shalygin@...il.com, andy.shevchenko@...il.com,
        platform-driver-x86@...r.kernel.org, Tor Vic <torvic9@...lbox.org>,
        kernel test robot <lkp@...el.com>,
        Jean Delvare <jdelvare@...e.com>,
        Jonathan Corbet <corbet@....net>, linux-hwmon@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 1/2] hwmon: (asus_wmi_ec_sensors) Support B550 Asus
 WMI.

On 10/11/21 12:55 PM, Denis Pauk wrote:
> Linux HWMON sensors driver for ASUS motherboards to read
> sensors from the embedded controller.
> 
> Many ASUS motherboards do not publish all the available
> sensors via the Super I/O chip but the missing ones are
> available through the embedded controller (EC) registers.
> 
> This driver implements reading those sensor data via the
> WMI method BREC, which is known to be present in all ASUS
> motherboards based on the AMD 500 series chipsets (and
> probably is available in other models too). The driver
> needs to know exact register addresses for the sensors and
> thus support for each motherboard has to be added explicitly.
> 
> The EC registers do not provide critical values for the
> sensors and as such they are not published to the HWMON.
> 
> Supported motherboards:
> * PRIME X570-PRO
> * ROG CROSSHAIR VIII HERO
> * ROG CROSSHAIR VIII DARK HERO
> * ROG CROSSHAIR VIII FORMULA
> * ROG STRIX X570-E GAMING
> * ROG STRIX B550-E GAMING
> 
> Signed-off-by: Denis Pauk <pauk.denis@...il.com>
> Co-developed-by: Eugene Shalygin <eugene.shalygin@...il.com>
> Signed-off-by: Eugene Shalygin <eugene.shalygin@...il.com>
> Tested-by: Tor Vic <torvic9@...lbox.org>
> Reported-by: kernel test robot <lkp@...el.com>
> 
> ---
> Changes in v5:
> - Fixes build issue reported by kernel test robot with disabled ACPI_WMI.
> 
> Changes in v4:
>   - implement wmi driver instead platform driver.
> 
> Changes in v3:
>   - Use MODULE_DEVICE_TABLE for match devices.
>   - Use get_unaligned_be32 instead incorrectly used get_unaligned_le32.
>   - Add documentaion for driver.
> 
> Changes in v2:
>   - Use utf8s_to_utf16s/utf16s_to_utf8s instead handmade fuctions.
>   - Use post increment.
>   - Use get_unaligned* for convert values.
>   - Use PTR_ERR_OR_ZERO.
>   - Specify per-board sensors in a declarative way (by Eugene Shalygin).
> ---
>   Documentation/hwmon/asus_wmi_ec_sensors.rst |  35 ++

This also needs to be added to index.rst in the same directory.

>   MAINTAINERS                                 |   7 +
>   drivers/hwmon/Kconfig                       |  11 +
>   drivers/hwmon/Makefile                      |   1 +
>   drivers/hwmon/asus_wmi_ec_sensors.c         | 648 ++++++++++++++++++++
>   5 files changed, 702 insertions(+)
>   create mode 100644 Documentation/hwmon/asus_wmi_ec_sensors.rst
>   create mode 100644 drivers/hwmon/asus_wmi_ec_sensors.c
> 
> diff --git a/Documentation/hwmon/asus_wmi_ec_sensors.rst b/Documentation/hwmon/asus_wmi_ec_sensors.rst
> new file mode 100644
> index 000000000000..e4f603804a82
> --- /dev/null
> +++ b/Documentation/hwmon/asus_wmi_ec_sensors.rst
> @@ -0,0 +1,35 @@
> +Kernel driver asus-wmi-ec-sensors
> +=================================
> +
> +Supported boards:
> + * PRIME X570-PRO,
> + * Pro WS X570-ACE,
> + * ROG CROSSHAIR VIII DARK HERO,
> + * ROG CROSSHAIR VIII FORMULA,
> + * ROG CROSSHAIR VIII HERO,
> + * ROG STRIX B550-E GAMING,
> + * ROG STRIX X570-E GAMING.
> +
> +Authors:
> +        Eugene Shalygin <eugene.shalygin@...il.com>
> +
> +Description:
> +------------
> +ASUS mainboards publish hardware monitoring information via Super I/O
> +chip and the ACPI embedded controller (EC) registers. Some of the sensors
> +are only available via the EC.
> +
> +ASUS WMI interface provides a method (BREC) to read data from EC registers,
> +which is utilized by this driver to publish those sensor readings to the
> +HWMON system. The driver is aware of and reads the following sensors:
> +
> +1. Chipset (PCH) temperature
> +2. CPU package temperature
> +3. Motherboard temperature
> +4. Readings from the T_Sensor header
> +5. VRM temperature
> +6. CPU_Opt fan RPM
> +7. Chipset fan RPM
> +8. Readings from the "Water flow meter" header (RPM)
> +9. Readings from the "Water In" and "Water Out" temperature headers
> +10. CPU current
> diff --git a/MAINTAINERS b/MAINTAINERS
> index cc5eaf4e65dc..05448435991d 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -2937,6 +2937,13 @@ W:	http://acpi4asus.sf.net
>   F:	drivers/platform/x86/asus*.c
>   F:	drivers/platform/x86/eeepc*.c
>   
> +ASUS WMI HARDWARE MONITOR DRIVER
> +M:	Eugene Shalygin <eugene.shalygin@...il.com>
> +M:	Denis Pauk <pauk.denis@...il.com>
> +L:	linux-hwmon@...r.kernel.org
> +S:	Maintained
> +F:	drivers/hwmon/asus_wmi_ec_sensors.c
> +
>   ASUS WIRELESS RADIO CONTROL DRIVER
>   M:	João Paulo Rechi Vita <jprvita@...il.com>
>   L:	platform-driver-x86@...r.kernel.org
> diff --git a/drivers/hwmon/Kconfig b/drivers/hwmon/Kconfig
> index 7fde4c6e1e7f..430a438432a0 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -2215,6 +2215,17 @@ config SENSORS_ATK0110
>   	  This driver can also be built as a module. If so, the module
>   	  will be called asus_atk0110.
>   
> +config SENSORS_ASUS_WMI_EC
> +	tristate "ASUS WMI B550/X570"
> +	help
> +	  If you say yes here you get support for the ACPI embedded controller
> +	  hardware monitoring interface found in B550/X570 ASUS motherboards.
> +	  This driver will provide readings of fans, voltages and temperatures
> +	  through the system firmware.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called asus_wmi_sensors_ec.
> +
>   endif # ACPI
>   
>   endif # HWMON
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index baee6a8d4dd1..aae2ff5c7335 100644
> --- a/drivers/hwmon/Makefile
> +++ b/drivers/hwmon/Makefile
> @@ -9,6 +9,7 @@ obj-$(CONFIG_HWMON_VID)		+= hwmon-vid.o
>   # APCI drivers
>   obj-$(CONFIG_SENSORS_ACPI_POWER) += acpi_power_meter.o
>   obj-$(CONFIG_SENSORS_ATK0110)	+= asus_atk0110.o
> +obj-$(CONFIG_SENSORS_ASUS_WMI_EC)	+= asus_wmi_ec_sensors.o
>   
>   # Native drivers
>   # asb100, then w83781d go first, as they can override other drivers' addresses.
> diff --git a/drivers/hwmon/asus_wmi_ec_sensors.c b/drivers/hwmon/asus_wmi_ec_sensors.c
> new file mode 100644
> index 000000000000..f9d8a0be7bea
> --- /dev/null
> +++ b/drivers/hwmon/asus_wmi_ec_sensors.c
> @@ -0,0 +1,648 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * HWMON driver for ASUS B550/X570 motherboards that publish sensor
> + * values via the embedded controller registers.
> + *
> + * Copyright (C) 2021 Eugene Shalygin <eugene.shalygin@...il.com>
> + * Copyright (C) 2018-2019 Ed Brindley <kernel@...davale.org>
> + *
> + * EC provides:
> + * Chipset temperature,
> + * CPU temperature,
> + * Motherboard temperature,
> + * T_Sensor temperature,
> + * VRM  temperature,
> + * Water In temperature,
> + * Water Out temperature,
> + * CPU Optional Fan RPM,
> + * Chipset Fan RPM,
> + * Water Flow Fan RPM,
> + * CPU current.
> + *
> + */
> +#include <asm/unaligned.h>
> +#include <linux/acpi.h>
> +#include <linux/dmi.h>
> +#include <linux/hwmon.h>
> +#include <linux/hwmon-sysfs.h>
> +#include <linux/init.h>
> +#include <linux/jiffies.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/mutex.h>
> +#include <linux/nls.h>
> +#include <linux/units.h>
> +#include <linux/wmi.h>
> +
> +#define ASUSWMI_MONITORING_GUID		"466747A0-70EC-11DE-8A39-0800200C9A66"
> +#define ASUSWMI_METHODID_BLOCK_READ_EC		0x42524543 /* BREC */
> +
> +#define ASUS_WMI_BLOCK_READ_REGISTERS_MAX 0x10 /* from the ASUS DSDT source */
> +/* from the ASUS_WMI_BLOCK_READ_REGISTERS_MAX value */
> +#define ASUS_WMI_MAX_BUF_LEN 0x80
> +#define MAX_SENSOR_LABEL_LENGTH 0x10
> +
> +static u32 hwmon_attributes[] = {
> +	[hwmon_chip] = HWMON_C_REGISTER_TZ,
> +	[hwmon_temp] = HWMON_T_INPUT | HWMON_T_LABEL,
> +	[hwmon_in] = HWMON_I_INPUT | HWMON_I_LABEL,
> +	[hwmon_curr] = HWMON_C_INPUT | HWMON_C_LABEL,
> +	[hwmon_fan] = HWMON_F_INPUT | HWMON_F_LABEL,
> +};
> +
> +struct asus_wmi_ec_sensor_address {
> +	u8 index;
> +	u8 bank;
> +	u8 size;
> +};
> +
> +#define MAKE_SENSOR_ADDRESS(size_i, bank_i, index_i) \
> +	{ .size = size_i,\
> +	   .bank = bank_i,\
> +	   .index = index_i}
> +
> +struct ec_sensor_info {
> +	char label[MAX_SENSOR_LABEL_LENGTH];
> +	enum hwmon_sensor_types type;
> +	struct asus_wmi_ec_sensor_address addr;
> +};
> +
> +#define EC_SENSOR(sensor_label, sensor_type, size, bank, index) \
> +	{ .label = sensor_label,\
> +	.type = sensor_type, \
> +	.addr = MAKE_SENSOR_ADDRESS(size, bank, index) \
> +	}
> +
> +enum known_ec_sensor {
> +	SENSOR_TEMP_CHIPSET,
> +	SENSOR_TEMP_CPU,
> +	SENSOR_TEMP_MB,
> +	SENSOR_TEMP_T_SENSOR,
> +	SENSOR_TEMP_VRM,
> +	SENSOR_FAN_CPU_OPT,
> +	SENSOR_FAN_CHIPSET,
> +	SENSOR_FAN_WATER_FLOW,
> +	SENSOR_CURR_CPU,
> +	SENSOR_TEMP_WATER_IN,
> +	SENSOR_TEMP_WATER_OUT,
> +	SENSOR_MAX
> +};
> +
> +/*
> + * All the known sensors for ASUS EC controllers
> + */
> +static const struct ec_sensor_info known_ec_sensors[] = {
> +	[SENSOR_TEMP_CHIPSET] = EC_SENSOR("Chipset", hwmon_temp, 1, 0x00, 0x3a),
> +	[SENSOR_TEMP_CPU] = EC_SENSOR("CPU", hwmon_temp, 1, 0x00, 0x3b),
> +	[SENSOR_TEMP_MB] = EC_SENSOR("Motherboard", hwmon_temp, 1, 0x00, 0x3c),
> +	[SENSOR_TEMP_T_SENSOR] = EC_SENSOR("T_Sensor", hwmon_temp, 1, 0x00, 0x3d),
> +	[SENSOR_TEMP_VRM] = EC_SENSOR("VRM", hwmon_temp, 1, 0x00, 0x3e),
> +	[SENSOR_FAN_CPU_OPT] = EC_SENSOR("CPU_Opt", hwmon_fan, 2, 0x00, 0xb0),
> +	[SENSOR_FAN_CHIPSET] = EC_SENSOR("Chipset", hwmon_fan, 2, 0x00, 0xb4),
> +	[SENSOR_FAN_WATER_FLOW] = EC_SENSOR("Water_Flow", hwmon_fan, 2, 0x00, 0xbc),
> +	[SENSOR_CURR_CPU] = EC_SENSOR("CPU", hwmon_curr, 1, 0x00, 0xf4),
> +	[SENSOR_TEMP_WATER_IN] = EC_SENSOR("Water_In", hwmon_temp, 1, 0x01, 0x00),
> +	[SENSOR_TEMP_WATER_OUT] = EC_SENSOR("Water_Out", hwmon_temp, 1, 0x01, 0x01),
> +};
> +
> +struct asus_wmi_data {
> +	const enum known_ec_sensor known_board_sensors[SENSOR_MAX + 1];
> +};
> +
> +/* boards with EC support */
> +static struct asus_wmi_data sensors_board_PW_X570_P = {
> +	.known_board_sensors = {
> +		SENSOR_TEMP_CHIPSET, SENSOR_TEMP_CPU, SENSOR_TEMP_MB, SENSOR_TEMP_VRM,
> +		SENSOR_FAN_CHIPSET,
> +		SENSOR_MAX
> +	},
> +};
> +
> +static struct asus_wmi_data sensors_board_PW_X570_A = {
> +	.known_board_sensors = {
> +		SENSOR_TEMP_CHIPSET, SENSOR_TEMP_CPU, SENSOR_TEMP_MB, SENSOR_TEMP_VRM,
> +		SENSOR_FAN_CHIPSET,
> +		SENSOR_CURR_CPU,
> +		SENSOR_MAX
> +	},
> +};
> +
> +static struct asus_wmi_data sensors_board_R_C8H = {
> +	.known_board_sensors = {
> +		SENSOR_TEMP_CHIPSET, SENSOR_TEMP_CPU, SENSOR_TEMP_MB,
> +		SENSOR_TEMP_T_SENSOR, SENSOR_TEMP_VRM,
> +		SENSOR_TEMP_WATER_IN, SENSOR_TEMP_WATER_OUT,
> +		SENSOR_FAN_CPU_OPT, SENSOR_FAN_CHIPSET, SENSOR_FAN_WATER_FLOW,
> +		SENSOR_CURR_CPU,
> +		SENSOR_MAX
> +	},
> +};
> +
> +/* Same as Hero but without chipset fan */
> +static struct asus_wmi_data sensors_board_R_C8DH = {
> +	.known_board_sensors = {
> +		SENSOR_TEMP_CHIPSET, SENSOR_TEMP_CPU, SENSOR_TEMP_MB,
> +		SENSOR_TEMP_T_SENSOR, SENSOR_TEMP_VRM,
> +		SENSOR_TEMP_WATER_IN, SENSOR_TEMP_WATER_OUT,
> +		SENSOR_FAN_CPU_OPT, SENSOR_FAN_WATER_FLOW,
> +		SENSOR_CURR_CPU,
> +		SENSOR_MAX
> +	},
> +};
> +
> +/* Same as Hero but without water */
> +static struct asus_wmi_data sensors_board_R_C8F = {
> +	.known_board_sensors = {
> +		SENSOR_TEMP_CHIPSET, SENSOR_TEMP_CPU, SENSOR_TEMP_MB,
> +		SENSOR_TEMP_T_SENSOR, SENSOR_TEMP_VRM,
> +		SENSOR_FAN_CPU_OPT, SENSOR_FAN_CHIPSET,
> +		SENSOR_CURR_CPU,
> +		SENSOR_MAX
> +	},
> +};
> +
> +static struct asus_wmi_data sensors_board_RS_B550_E_G = {
> +	.known_board_sensors = {
> +		SENSOR_TEMP_CHIPSET, SENSOR_TEMP_CPU, SENSOR_TEMP_MB,
> +		SENSOR_TEMP_T_SENSOR, SENSOR_TEMP_VRM,
> +		SENSOR_FAN_CPU_OPT,
> +		SENSOR_CURR_CPU,
> +		SENSOR_MAX
> +	},
> +};
> +
> +static struct asus_wmi_data sensors_board_RS_X570_E_G = {
> +	.known_board_sensors = {
> +		SENSOR_TEMP_CHIPSET, SENSOR_TEMP_CPU, SENSOR_TEMP_MB,
> +		SENSOR_TEMP_T_SENSOR, SENSOR_TEMP_VRM,
> +		SENSOR_FAN_CHIPSET,
> +		SENSOR_CURR_CPU,
> +		SENSOR_MAX
> +	},
> +};
> +
> +static struct asus_wmi_data *board_sensors;
> +
> +static int __init asus_wmi_dmi_matched(const struct dmi_system_id *d)
> +{
> +	board_sensors = d->driver_data;
> +	return 0;
> +}
> +
> +#define DMI_EXACT_MATCH_ASUS_BOARD_NAME(name, sensors) \
> +	{ \
> +		.callback = asus_wmi_dmi_matched, \
> +		.matches = { \
> +			DMI_EXACT_MATCH(DMI_BOARD_VENDOR, \
> +					"ASUSTeK COMPUTER INC."), \
> +			DMI_EXACT_MATCH(DMI_BOARD_NAME, name), \
> +		}, \
> +		.driver_data = sensors, \
> +	}
> +
> +static const struct dmi_system_id asus_wmi_ec_dmi_table[] = {
> +	DMI_EXACT_MATCH_ASUS_BOARD_NAME("PRIME X570-PRO", &sensors_board_PW_X570_P),
> +	DMI_EXACT_MATCH_ASUS_BOARD_NAME("Pro WS X570-ACE", &sensors_board_PW_X570_A),
> +	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG CROSSHAIR VIII DARK HERO", &sensors_board_R_C8DH),
> +	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG CROSSHAIR VIII FORMULA", &sensors_board_R_C8F),
> +	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG CROSSHAIR VIII HERO", &sensors_board_R_C8H),
> +	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG STRIX B550-E GAMING", &sensors_board_RS_B550_E_G),
> +	DMI_EXACT_MATCH_ASUS_BOARD_NAME("ROG STRIX X570-E GAMING", &sensors_board_RS_X570_E_G),
> +	{}
> +};
> +MODULE_DEVICE_TABLE(dmi, asus_wmi_ec_dmi_table);
> +
> +struct ec_sensor {
> +	enum known_ec_sensor info_index;
> +	u32 cached_value;
> +};
> +
> +/**
> + * struct asus_wmi_ec_info - sensor info.
> + * @sensors: list of sensors.
> + * @read_arg: UTF-16 string to pass to BRxx() WMI function.
> + * @read_buffer: decoded output from WMI result.
> + * @nr_sensors: number of board EC sensors.
> + * @nr_registers: number of EC registers to read (sensor might span more than
> + *                         1 register).
> + * @last_updated: in jiffies.
> + */
> +struct asus_wmi_ec_info {
> +	struct ec_sensor sensors[SENSOR_MAX];
> +	char read_arg[((ASUS_WMI_BLOCK_READ_REGISTERS_MAX * 4) + 1) * 2];
> +	u8 read_buffer[ASUS_WMI_BLOCK_READ_REGISTERS_MAX];
> +	unsigned int nr_sensors;
> +	unsigned int nr_registers;
> +	unsigned long last_updated;
> +};
> +
> +struct asus_wmi_sensors {
> +	/* lock access to instrnal cache */

internal ?

> +	struct mutex lock;
> +	struct asus_wmi_ec_info ec;
> +};
> +
> +static int asus_wmi_ec_fill_board_sensors(struct asus_wmi_ec_info *ec)
> +{
> +	const enum known_ec_sensor *bsi;
> +	struct ec_sensor *s = ec->sensors;
> +	int i;
> +
> +	if (!board_sensors)
> +		return -ENODEV;
> +
> +	bsi = board_sensors->known_board_sensors;
> +	ec->nr_sensors = 0;
> +	ec->nr_registers = 0;
> +
> +	for (i = 0; i < SENSOR_MAX && bsi[i] != SENSOR_MAX; i++) {
> +		s[i].info_index = bsi[i];
> +		s[i].cached_value = 0;
> +		ec->nr_sensors++;
> +		ec->nr_registers += known_ec_sensors[bsi[i]].addr.size;
> +	}
> +
> +	return 0;
> +}
> +
> +/*
> + * The next four functions converts to/from BRxx string argument format
> + * The format of the string is as follows:
> + * The string consists of two-byte UTF-16 characters
> + * The value of the very first byte int the string is equal to the total length
> + * of the next string in bytes, thus excluding the first two-byte character
> + * The rest of the string encodes pairs of (bank, index) pairs, where both
> + * values are byte-long (0x00 to 0xFF)
> + * Numbers are encoded as UTF-16 hex values
> + */
> +static void asus_wmi_ec_decode_reply_buffer(const u8 *inp, u8 *out)
> +{
> +	unsigned int len = ACPI_MIN(ASUS_WMI_MAX_BUF_LEN, inp[0] / 4);
> +	char buffer[ASUS_WMI_MAX_BUF_LEN * 2];
> +	const char *pos = buffer;
> +	const u8 *data = inp + 2;
> +	unsigned int i;
> +
> +	utf16s_to_utf8s((wchar_t *)data, len * 2,  UTF16_LITTLE_ENDIAN, buffer, len * 2);
> +
> +	for (i = 0; i < len; i++, pos += 2)
> +		out[i] = (hex_to_bin(pos[0]) << 4) + hex_to_bin(pos[1]);
> +}
> +
> +static void asus_wmi_ec_encode_registers(u16 *registers, u8 len, char *out)
> +{
> +	char buffer[ASUS_WMI_MAX_BUF_LEN * 2];
> +	char *pos = buffer;
> +	unsigned int i;
> +	u8 byte;
> +
> +	*out++ = len * 8;
> +	*out++ = 0;
> +
> +	for (i = 0; i < len; i++) {
> +		byte = registers[i] >> 8;
> +		*pos = hex_asc_hi(byte);
> +		pos++;
> +		*pos = hex_asc_lo(byte);
> +		pos++;
> +		byte = registers[i];
> +		*pos = hex_asc_hi(byte);
> +		pos++;
> +		*pos = hex_asc_lo(byte);
> +		pos++;
> +	}
> +
> +	utf8s_to_utf16s(buffer, len * 4, UTF16_LITTLE_ENDIAN, (wchar_t *)out, len * 4);
> +}
> +
> +static void asus_wmi_ec_make_block_read_query(struct asus_wmi_ec_info *ec)
> +{
> +	u16 registers[ASUS_WMI_BLOCK_READ_REGISTERS_MAX];
> +	const struct ec_sensor_info *si;
> +	int i, j, register_idx = 0;
> +
> +	/*
> +	 * if we can get values for all the registers in a single query,
> +	 * the query will not change from call to call
> +	 */
> +	if (ec->nr_registers <= ASUS_WMI_BLOCK_READ_REGISTERS_MAX &&
> +	    ec->read_arg[0] > 0) {
> +		/* no need to update */
> +		return;
> +	}
> +
> +	for (i = 0; i < ec->nr_sensors; i++) {
> +		si = &known_ec_sensors[ec->sensors[i].info_index];
> +		for (j = 0; j < si->addr.size;
> +		     j++, register_idx++) {
> +			registers[register_idx] = (si->addr.bank << 8) + si->addr.index + j;
> +		}
> +	}
> +
> +	asus_wmi_ec_encode_registers(registers, ec->nr_registers, ec->read_arg);
> +}
> +
> +static int asus_wmi_ec_block_read(u32 method_id, char *query, u8 *out)
> +{
> +#if IS_ENABLED(CONFIG_ACPI_WMI)
> +	struct acpi_buffer output = { ACPI_ALLOCATE_BUFFER,
> +				      NULL };
> +	struct acpi_buffer input;
> +	union acpi_object *obj;
> +	acpi_status status;
> +
> +	/* the first byte of the BRxx() argument string has to be the string size */
> +	input.length = (acpi_size)query[0] + 2;
> +	input.pointer = query;
> +	status = wmi_evaluate_method(ASUSWMI_MONITORING_GUID, 0, method_id, &input,
> +				     &output);
> +	if (ACPI_FAILURE(status))
> +		return -EIO;
> +
> +	obj = output.pointer;
> +	if (!obj || obj->type != ACPI_TYPE_BUFFER) {
> +		if (!obj)
> +			acpi_os_free(output.pointer);

This code looks wrong. With obj == output.pointer, output.pointer
is always NULL here. This should be
		if (obj)
			acpi_os_free(obj);
but then since acpi_os_free() calls free(), which does
a NULL pointer check,
		acpi_os_free(obj);
should be just as good.

> +
> +		return -EIO;
> +	}
> +	asus_wmi_ec_decode_reply_buffer(obj->buffer.pointer, out);
> +	acpi_os_free(output.pointer);
> +	return 0;
> +#else
> +	return -EOPNOTSUPP;
> +#endif
> +}
> +
> +static int asus_wmi_ec_update_ec_sensors(struct asus_wmi_ec_info *ec)
> +{
> +	const struct ec_sensor_info *si;
> +	struct ec_sensor *s;
> +

This empty line is confusing; it suggests the end of the variable list
which is not the case. Please drop.

> +	int status;
> +	u8 i_sensor, read_reg_ct;
> +
> +	asus_wmi_ec_make_block_read_query(ec);
> +	status = asus_wmi_ec_block_read(ASUSWMI_METHODID_BLOCK_READ_EC,
> +					ec->read_arg,
> +					ec->read_buffer);
> +	if (status)
> +		return status;
> +
> +	read_reg_ct = 0;
> +	for (i_sensor = 0; i_sensor < ec->nr_sensors; i_sensor++) {
> +		s = &ec->sensors[i_sensor];
> +		si = &known_ec_sensors[s->info_index];
> +
> +		switch (si->addr.size) {
> +		case 1:
> +			s->cached_value = ec->read_buffer[read_reg_ct];
> +			break;
> +		case 2:
> +			s->cached_value = get_unaligned_be16(&ec->read_buffer[read_reg_ct]);
> +			break;
> +		case 4:
> +			s->cached_value = get_unaligned_be32(&ec->read_buffer[read_reg_ct]);
> +			break;
> +		default:
> +			s->cached_value =  0;
> +		}
> +		read_reg_ct += si->addr.size;
> +	}
> +	return 0;
> +}
> +
> +static int asus_wmi_ec_scale_sensor_value(u32 value, int data_type)
> +{
> +	switch (data_type) {
> +	case hwmon_curr:
> +	case hwmon_temp:
> +	case hwmon_in:
> +		return value * KILO;
> +	default:
> +		return value;
> +	}
> +}
> +
> +static int asus_wmi_ec_find_sensor_index(const struct asus_wmi_ec_info *ec,
> +					 enum hwmon_sensor_types type, int channel)
> +{
> +	int i;
> +
> +	for (i = 0; i < ec->nr_sensors; i++) {
> +		if (known_ec_sensors[ec->sensors[i].info_index].type == type) {
> +			if (channel == 0)
> +				return i;
> +
> +			channel--;
> +		}
> +	}
> +	return -EINVAL;
> +}
> +
> +static int asus_wmi_ec_get_cached_value_or_update(int sensor_index,
> +						  struct asus_wmi_sensors *state,
> +						  u32 *value)
> +{
> +	int ret;
> +
> +	if (time_after(jiffies, state->ec.last_updated + HZ)) {
> +		ret = asus_wmi_ec_update_ec_sensors(&state->ec);
> +		if (ret)
> +			return ret;
> +
> +		state->ec.last_updated = jiffies;
> +	}
> +
> +	*value = state->ec.sensors[sensor_index].cached_value;
> +	return 0;
> +}
> +
> +/*
> + * Now follow the functions that implement the hwmon interface
> + */
> +
> +static int asus_wmi_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> +				  u32 attr, int channel, long *val)
> +{
> +	struct asus_wmi_sensors *sensor_data = dev_get_drvdata(dev);
> +	int ret, sidx, info_index;
> +	u32 value = 0;
> +
> +	sidx = asus_wmi_ec_find_sensor_index(&sensor_data->ec, type, channel);
> +	if (sidx < 0)
> +		return sidx;
> +
> +	mutex_lock(&sensor_data->lock);
> +	ret = asus_wmi_ec_get_cached_value_or_update(sidx, sensor_data, &value);
> +	mutex_unlock(&sensor_data->lock);
> +	if (ret)
> +		return ret;
> +
> +	info_index = sensor_data->ec.sensors[sidx].info_index;
> +	*val = asus_wmi_ec_scale_sensor_value(value,
> +					      known_ec_sensors[info_index].type);
> +
> +	return ret;
> +}
> +
> +static int asus_wmi_ec_hwmon_read_string(struct device *dev,
> +					 enum hwmon_sensor_types type, u32 attr,
> +					 int channel, const char **str)
> +{
> +	struct asus_wmi_sensors *sensor_data = dev_get_drvdata(dev);
> +	int sensor_index;
> +
> +	sensor_index = asus_wmi_ec_find_sensor_index(&sensor_data->ec, type, channel);
> +	*str = known_ec_sensors[sensor_data->ec.sensors[sensor_index].info_index].label;
> +
> +	return 0;
> +}
> +
> +static umode_t asus_wmi_ec_hwmon_is_visible(const void *drvdata,
> +					    enum hwmon_sensor_types type, u32 attr,
> +					    int channel)
> +{
> +	int index;
> +	const struct asus_wmi_sensors *sensor_data = drvdata;
> +
> +	index = asus_wmi_ec_find_sensor_index(&sensor_data->ec, type, channel);
> +
> +	return index == 0xff ? 0 : 0444;
> +}
> +
> +static int asus_wmi_hwmon_add_chan_info(struct hwmon_channel_info *asus_wmi_hwmon_chan,
> +					struct device *dev, int num,
> +					enum hwmon_sensor_types type, u32 config)
> +{
> +	u32 *cfg;
> +
> +	cfg = devm_kcalloc(dev, num + 1, sizeof(*cfg), GFP_KERNEL);
> +	if (!cfg)
> +		return -ENOMEM;
> +
> +	asus_wmi_hwmon_chan->type = type;
> +	asus_wmi_hwmon_chan->config = cfg;
> +	memset32(cfg, config, num);
> +
> +	return 0;
> +}
> +
> +static const struct hwmon_ops asus_wmi_ec_hwmon_ops = {
> +	.is_visible = asus_wmi_ec_hwmon_is_visible,
> +	.read = asus_wmi_ec_hwmon_read,
> +	.read_string = asus_wmi_ec_hwmon_read_string,
> +};
> +
> +static struct hwmon_chip_info asus_wmi_ec_chip_info = {
> +	.ops = &asus_wmi_ec_hwmon_ops,
> +};
> +
> +static int asus_wmi_ec_configure_sensor_setup(struct device *dev,
> +					      struct asus_wmi_sensors *sensor_data)
> +{
> +	struct hwmon_channel_info *asus_wmi_hwmon_chan;
> +	const struct hwmon_channel_info **ptr_asus_wmi_ci;
> +	int nr_count[hwmon_max] = { 0 }, nr_types = 0;
> +	const struct hwmon_chip_info *chip_info;
> +	const struct ec_sensor_info *si;
> +	enum hwmon_sensor_types type;
> +	struct device *hwdev;
> +	int i, ret;
> +
> +	ret = asus_wmi_ec_fill_board_sensors(&sensor_data->ec);
> +	if (ret)
> +		return ret;
> +
> +	if (!sensor_data->ec.nr_sensors)
> +		return -ENODEV;
> +
> +	for (i = 0; i < sensor_data->ec.nr_sensors; i++) {
> +		si = &known_ec_sensors[sensor_data->ec.sensors[i].info_index];
> +		if (!nr_count[si->type])
> +			nr_types++;
> +		nr_count[si->type]++;
> +	}
> +
> +	if (nr_count[hwmon_temp]) {
> +		nr_count[hwmon_chip]++;
> +		nr_types++;
> +	}
> +
> +	asus_wmi_hwmon_chan = devm_kcalloc(dev, nr_types,
> +					   sizeof(*asus_wmi_hwmon_chan),
> +					   GFP_KERNEL);
> +	if (!asus_wmi_hwmon_chan)
> +		return -ENOMEM;
> +
> +	ptr_asus_wmi_ci = devm_kcalloc(dev, nr_types + 1,
> +				       sizeof(*ptr_asus_wmi_ci), GFP_KERNEL);
> +	if (!ptr_asus_wmi_ci)
> +		return -ENOMEM;
> +
> +	asus_wmi_ec_chip_info.info = ptr_asus_wmi_ci;
> +	chip_info = &asus_wmi_ec_chip_info;
> +
> +	for (type = 0; type < hwmon_max; type++) {
> +		if (!nr_count[type])
> +			continue;
> +
> +		ret = asus_wmi_hwmon_add_chan_info(asus_wmi_hwmon_chan, dev,
> +						   nr_count[type], type,
> +						   hwmon_attributes[type]);
> +		if (ret)
> +			return ret;
> +
> +		*ptr_asus_wmi_ci++ = asus_wmi_hwmon_chan++;
> +	}
> +
> +	dev_dbg(dev, "board has %d EC sensors that span %d registers",
> +		sensor_data->ec.nr_sensors,
> +		sensor_data->ec.nr_registers);
> +
> +	hwdev = devm_hwmon_device_register_with_info(dev, KBUILD_MODNAME,
> +						     sensor_data, chip_info, NULL);
> +
> +	return PTR_ERR_OR_ZERO(hwdev);
> +}
> +
> +static int asus_wmi_probe(struct wmi_device *wdev, const void *context)
> +{
> +	struct asus_wmi_sensors *sensor_data;
> +	struct device *dev = &wdev->dev;
> +
> +	if (!dmi_check_system(asus_wmi_ec_dmi_table))
> +		return -ENODEV;
> +
> +	sensor_data = devm_kzalloc(dev, sizeof(struct asus_wmi_sensors),
> +				   GFP_KERNEL);
> +	if (!sensor_data)
> +		return -ENOMEM;
> +
> +	mutex_init(&sensor_data->lock);
> +
> +	dev_set_drvdata(dev, sensor_data);
> +
> +	/* ec init */
> +	return asus_wmi_ec_configure_sensor_setup(dev,
> +						  sensor_data);
> +}
> +
> +static const struct wmi_device_id asus_ec_wmi_id_table[] = {
> +	{ ASUSWMI_MONITORING_GUID, NULL },
> +	{ }
> +};
> +
> +static struct wmi_driver asus_sensors_wmi_driver = {
> +	.driver = {
> +		.name = KBUILD_MODNAME,
> +	},
> +	.id_table = asus_ec_wmi_id_table,
> +	.probe = asus_wmi_probe,
> +};
> +module_wmi_driver(asus_sensors_wmi_driver);
> +
> +MODULE_AUTHOR("Ed Brindley <kernel@...davale.org>");
> +MODULE_AUTHOR("Eugene Shalygin <eugene.shalygin@...il.com>");
> +MODULE_DESCRIPTION("Asus WMI Sensors Driver");
> +MODULE_LICENSE("GPL");
> 

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