Message-ID: <4710352.31r3eYUQgx@natalenko.name>
Date:   Tue, 25 Jan 2022 09:49:37 +0100
From:   Oleksandr Natalenko <oleksandr@...alenko.name>
To:     Eugene Shalygin <eugene.shalygin@...il.com>
Cc:     andy.shevchenko@...il.com, pauk.denis@...il.com,
        Jean Delvare <jdelvare@...e.com>,
        Guenter Roeck <linux@...ck-us.net>,
        linux-kernel@...r.kernel.org, linux-hwmon@...r.kernel.org
Subject: Re: [ASUS EC Sensors v8 1/3] hwmon: (asus-ec-sensors) add driver for ASUS EC

On pondělí 24. ledna 2022 2:56:43 CET Eugene Shalygin wrote:
> This driver provides the same data as the asus_wmi_ec_sensors driver
> (and gets it from the same source) but does not use WMI, polling
> the ACPI EC directly.
> 
> That provides two enhancements: sensor reading became quicker (on some
> systems or kernel configuration it took almost a full second to read
> all the sensors, that transfers less than 15 bytes of data), the driver
> became more flexible. The driver now relies on ACPI mutex to lock access
> to the EC in the same way as the WMI code does.
> 
> Signed-off-by: Eugene Shalygin <eugene.shalygin@...il.com>

Given minor changes against v7, I think my "Tested-by:" should have been preserved.

> ---
>  MAINTAINERS                     |   6 +
>  drivers/hwmon/Kconfig           |  11 +
>  drivers/hwmon/Makefile          |   1 +
>  drivers/hwmon/asus-ec-sensors.c | 694 ++++++++++++++++++++++++++++++++
>  4 files changed, 712 insertions(+)
>  create mode 100644 drivers/hwmon/asus-ec-sensors.c
> 
> diff --git a/MAINTAINERS b/MAINTAINERS
> index fddd28d3db15..845f09bc0457 100644
> --- a/MAINTAINERS
> +++ b/MAINTAINERS
> @@ -3012,6 +3012,12 @@ L:	linux-hwmon@...r.kernel.org
>  S:	Maintained
>  F:	drivers/hwmon/asus_wmi_ec_sensors.c
>  
> +ASUS EC HARDWARE MONITOR DRIVER
> +M:	Eugene Shalygin <eugene.shalygin@...il.com>
> +L:	linux-hwmon@...r.kernel.org
> +S:	Maintained
> +F:	drivers/hwmon/asus-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 43e5245874ad..2c16b19d2c03 100644
> --- a/drivers/hwmon/Kconfig
> +++ b/drivers/hwmon/Kconfig
> @@ -2253,6 +2253,17 @@ config SENSORS_ASUS_WMI_EC
>  	  This driver can also be built as a module. If so, the module
>  	  will be called asus_wmi_sensors_ec.
>  
> +config SENSORS_ASUS_EC
> +	tristate "ASUS EC Sensors"
> +	help
> +	  If you say yes here you get support for the ACPI embedded controller
> +	  hardware monitoring interface found in ASUS motherboards. The driver
> +	  currently supports B550/X570 boards, although other ASUS boards might
> +	  provide this monitoring interface as well.
> +
> +	  This driver can also be built as a module. If so, the module
> +	  will be called asus_ec_sensors.
> +
>  endif # ACPI
>  
>  endif # HWMON
> diff --git a/drivers/hwmon/Makefile b/drivers/hwmon/Makefile
> index 3a1551b3d570..2e5c216bb5d7 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_EC)	+= asus-ec-sensors.o
>  obj-$(CONFIG_SENSORS_ASUS_WMI)	+= asus_wmi_sensors.o
>  obj-$(CONFIG_SENSORS_ASUS_WMI_EC)	+= asus_wmi_ec_sensors.o
>  
> diff --git a/drivers/hwmon/asus-ec-sensors.c b/drivers/hwmon/asus-ec-sensors.c
> new file mode 100644
> index 000000000000..7285334c7d80
> --- /dev/null
> +++ b/drivers/hwmon/asus-ec-sensors.c
> @@ -0,0 +1,694 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * HWMON driver for ASUS motherboards that publish some sensor values
> + * via the embedded controller registers.
> + *
> + * Copyright (C) 2021 Eugene Shalygin <eugene.shalygin@...il.com>
> +
> + * 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
> + * - VRM Heat Sink fan RPM
> + * - Water Flow fan RPM
> + * - CPU current
> + */
> +
> +#include <linux/acpi.h>
> +#include <linux/bitops.h>
> +#include <linux/dev_printk.h>
> +#include <linux/dmi.h>
> +#include <linux/hwmon.h>
> +#include <linux/init.h>
> +#include <linux/jiffies.h>
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/platform_device.h>
> +#include <linux/sort.h>
> +#include <linux/units.h>
> +
> +#include <asm/unaligned.h>
> +
> +static char *mutex_path_override;
> +
> +/* Writing to this EC register switches EC bank */
> +#define ASUS_EC_BANK_REGISTER	0xff
> +#define SENSOR_LABEL_LEN	16
> +
> +/*
> + * Arbitrary set max. allowed bank number. Required for sorting banks and
> + * currently is overkill with just 2 banks used at max, but for the sake
> + * of alignment let's set it to a higher value.
> + */
> +#define ASUS_EC_MAX_BANK	3
> +
> +#define ACPI_LOCK_DELAY_MS	500
> +
> +/* ACPI mutex for locking access to the EC for the firmware */
> +#define ASUS_HW_ACCESS_MUTEX_ASMX	"\\AMW0.ASMX"
> +
> +/* There are two variants of the vendor spelling */
> +#define VENDOR_ASUS_UPPER_CASE	"ASUSTeK COMPUTER INC."
> +
> +typedef union {
> +	u32 value;
> +	struct {
> +		u8 index;
> +		u8 bank;
> +		u8 size;
> +		u8 dummy;
> +	} components;
> +} sensor_address;
> +
> +#define MAKE_SENSOR_ADDRESS(size, bank, index) {                               \
> +		.value = (size << 16) + (bank << 8) + index                    \
> +	}
> +
> +static u32 hwmon_attributes[hwmon_max] = {
> +	[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 ec_sensor_info {
> +	char label[SENSOR_LABEL_LEN];
> +	enum hwmon_sensor_types type;
> +	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 ec_sensors {
> +	/* chipset temperature [℃] */
> +	ec_sensor_temp_chipset,
> +	/* CPU temperature [℃] */
> +	ec_sensor_temp_cpu,
> +	/* motherboard temperature [℃] */
> +	ec_sensor_temp_mb,
> +	/* "T_Sensor" temperature sensor reading [℃] */
> +	ec_sensor_temp_t_sensor,
> +	/* VRM temperature [℃] */
> +	ec_sensor_temp_vrm,
> +	/* CPU_Opt fan [RPM] */
> +	ec_sensor_fan_cpu_opt,
> +	/* VRM heat sink fan [RPM] */
> +	ec_sensor_fan_vrm_hs,
> +	/* Chipset fan [RPM] */
> +	ec_sensor_fan_chipset,
> +	/* Water flow sensor reading [RPM] */
> +	ec_sensor_fan_water_flow,
> +	/* CPU current [A] */
> +	ec_sensor_curr_cpu,
> +	/* "Water_In" temperature sensor reading [℃] */
> +	ec_sensor_temp_water_in,
> +	/* "Water_Out" temperature sensor reading [℃] */
> +	ec_sensor_temp_water_out,
> +};
> +
> +#define SENSOR_TEMP_CHIPSET BIT(ec_sensor_temp_chipset)
> +#define SENSOR_TEMP_CPU BIT(ec_sensor_temp_cpu)
> +#define SENSOR_TEMP_MB BIT(ec_sensor_temp_mb)
> +#define SENSOR_TEMP_T_SENSOR BIT(ec_sensor_temp_t_sensor)
> +#define SENSOR_TEMP_VRM BIT(ec_sensor_temp_vrm)
> +#define SENSOR_FAN_CPU_OPT BIT(ec_sensor_fan_cpu_opt)
> +#define SENSOR_FAN_VRM_HS BIT(ec_sensor_fan_vrm_hs)
> +#define SENSOR_FAN_CHIPSET BIT(ec_sensor_fan_chipset)
> +#define SENSOR_FAN_WATER_FLOW BIT(ec_sensor_fan_water_flow)
> +#define SENSOR_CURR_CPU BIT(ec_sensor_curr_cpu)
> +#define SENSOR_TEMP_WATER_IN BIT(ec_sensor_temp_water_in)
> +#define SENSOR_TEMP_WATER_OUT BIT(ec_sensor_temp_water_out)
> +
> +/* All the known sensors for ASUS EC controllers */
> +static const struct ec_sensor_info known_ec_sensors[] = {
> +	[ec_sensor_temp_chipset] =
> +		EC_SENSOR("Chipset", hwmon_temp, 1, 0x00, 0x3a),
> +	[ec_sensor_temp_cpu] = EC_SENSOR("CPU", hwmon_temp, 1, 0x00, 0x3b),
> +	[ec_sensor_temp_mb] =
> +		EC_SENSOR("Motherboard", hwmon_temp, 1, 0x00, 0x3c),
> +	[ec_sensor_temp_t_sensor] =
> +		EC_SENSOR("T_Sensor", hwmon_temp, 1, 0x00, 0x3d),
> +	[ec_sensor_temp_vrm] = EC_SENSOR("VRM", hwmon_temp, 1, 0x00, 0x3e),
> +	[ec_sensor_fan_cpu_opt] =
> +		EC_SENSOR("CPU_Opt", hwmon_fan, 2, 0x00, 0xb0),
> +	[ec_sensor_fan_vrm_hs] = EC_SENSOR("VRM HS", hwmon_fan, 2, 0x00, 0xb2),
> +	[ec_sensor_fan_chipset] =
> +		EC_SENSOR("Chipset", hwmon_fan, 2, 0x00, 0xb4),
> +	[ec_sensor_fan_water_flow] =
> +		EC_SENSOR("Water_Flow", hwmon_fan, 2, 0x00, 0xbc),
> +	[ec_sensor_curr_cpu] = EC_SENSOR("CPU", hwmon_curr, 1, 0x00, 0xf4),
> +	[ec_sensor_temp_water_in] =
> +		EC_SENSOR("Water_In", hwmon_temp, 1, 0x01, 0x00),
> +	[ec_sensor_temp_water_out] =
> +		EC_SENSOR("Water_Out", hwmon_temp, 1, 0x01, 0x01),
> +};
> +
> +/* Shortcuts for common combinations */
> +#define SENSOR_SET_TEMP_CHIPSET_CPU_MB                                         \
> +	(SENSOR_TEMP_CHIPSET | SENSOR_TEMP_CPU | SENSOR_TEMP_MB)
> +#define SENSOR_SET_TEMP_WATER (SENSOR_TEMP_WATER_IN | SENSOR_TEMP_WATER_OUT)
> +
> +#define DMI_EXACT_MATCH_BOARD(vendor, name, sensors) {                         \
> +	.matches = {                                                           \
> +		DMI_EXACT_MATCH(DMI_BOARD_VENDOR, vendor),                     \
> +		DMI_EXACT_MATCH(DMI_BOARD_NAME, name),                         \
> +	},                                                                     \
> +	.driver_data = (void *)(sensors), \
> +}
> +
> +static const struct dmi_system_id asus_ec_dmi_table[] __initconst = {
> +	DMI_EXACT_MATCH_BOARD(VENDOR_ASUS_UPPER_CASE, "PRIME X570-PRO",
> +		SENSOR_SET_TEMP_CHIPSET_CPU_MB | SENSOR_TEMP_VRM |
> +		SENSOR_TEMP_T_SENSOR | SENSOR_FAN_CHIPSET),
> +	DMI_EXACT_MATCH_BOARD(VENDOR_ASUS_UPPER_CASE, "Pro WS X570-ACE",
> +		SENSOR_SET_TEMP_CHIPSET_CPU_MB | SENSOR_TEMP_VRM |
> +		SENSOR_FAN_CHIPSET | SENSOR_CURR_CPU),
> +	DMI_EXACT_MATCH_BOARD(VENDOR_ASUS_UPPER_CASE,
> +			      "ROG CROSSHAIR VIII DARK HERO",
> +		SENSOR_SET_TEMP_CHIPSET_CPU_MB | SENSOR_TEMP_T_SENSOR |
> +		SENSOR_TEMP_VRM | SENSOR_SET_TEMP_WATER |
> +		SENSOR_FAN_CPU_OPT | SENSOR_FAN_WATER_FLOW | SENSOR_CURR_CPU),
> +	DMI_EXACT_MATCH_BOARD(VENDOR_ASUS_UPPER_CASE,
> +			      "ROG CROSSHAIR VIII FORMULA",
> +		SENSOR_SET_TEMP_CHIPSET_CPU_MB | SENSOR_TEMP_T_SENSOR |
> +		SENSOR_TEMP_VRM | SENSOR_FAN_CPU_OPT | SENSOR_FAN_CHIPSET |
> +		SENSOR_CURR_CPU),
> +	DMI_EXACT_MATCH_BOARD(VENDOR_ASUS_UPPER_CASE, "ROG CROSSHAIR VIII HERO",
> +		SENSOR_SET_TEMP_CHIPSET_CPU_MB | SENSOR_TEMP_T_SENSOR |
> +		SENSOR_TEMP_VRM | SENSOR_SET_TEMP_WATER |
> +		SENSOR_FAN_CPU_OPT | SENSOR_FAN_CHIPSET |
> +		SENSOR_FAN_WATER_FLOW | SENSOR_CURR_CPU),
> +	DMI_EXACT_MATCH_BOARD(VENDOR_ASUS_UPPER_CASE,
> +			      "ROG CROSSHAIR VIII IMPACT",
> +		SENSOR_SET_TEMP_CHIPSET_CPU_MB | SENSOR_TEMP_T_SENSOR |
> +		SENSOR_TEMP_VRM | SENSOR_FAN_CHIPSET | SENSOR_CURR_CPU),
> +	DMI_EXACT_MATCH_BOARD(VENDOR_ASUS_UPPER_CASE, "ROG STRIX B550-E GAMING",
> +		SENSOR_SET_TEMP_CHIPSET_CPU_MB |
> +		SENSOR_TEMP_T_SENSOR |
> +		SENSOR_TEMP_VRM | SENSOR_FAN_CPU_OPT),
> +	DMI_EXACT_MATCH_BOARD(VENDOR_ASUS_UPPER_CASE, "ROG STRIX B550-I GAMING",
> +		SENSOR_SET_TEMP_CHIPSET_CPU_MB |
> +		SENSOR_TEMP_T_SENSOR |
> +		SENSOR_TEMP_VRM | SENSOR_FAN_VRM_HS | SENSOR_CURR_CPU),
> +	DMI_EXACT_MATCH_BOARD(VENDOR_ASUS_UPPER_CASE, "ROG STRIX X570-E GAMING",
> +		SENSOR_SET_TEMP_CHIPSET_CPU_MB |
> +		SENSOR_TEMP_T_SENSOR |
> +		SENSOR_TEMP_VRM | SENSOR_FAN_CHIPSET | SENSOR_CURR_CPU),
> +	DMI_EXACT_MATCH_BOARD(VENDOR_ASUS_UPPER_CASE, "ROG STRIX X570-F GAMING",
> +		SENSOR_SET_TEMP_CHIPSET_CPU_MB |
> +		SENSOR_TEMP_T_SENSOR | SENSOR_FAN_CHIPSET),
> +	DMI_EXACT_MATCH_BOARD(VENDOR_ASUS_UPPER_CASE, "ROG STRIX X570-I GAMING",
> +		SENSOR_TEMP_T_SENSOR | SENSOR_FAN_VRM_HS |
> +		SENSOR_FAN_CHIPSET | SENSOR_CURR_CPU),
> +	{}
> +};
> +
> +struct ec_sensor {
> +	unsigned int info_index;
> +	u32 cached_value;
> +};
> +
> +struct ec_sensors_data {
> +	unsigned long board_sensors;
> +	struct ec_sensor *sensors;
> +	/* EC registers to read from */
> +	u16 *registers;
> +	u8 *read_buffer;
> +	/* sorted list of unique register banks */
> +	u8 banks[ASUS_EC_MAX_BANK + 1];
> +	/* in jiffies */
> +	unsigned long last_updated;
> +	acpi_handle aml_mutex;
> +	/* number of board EC sensors */
> +	u8 nr_sensors;
> +	/*
> +	 * number of EC registers to read
> +	 * (sensor might span more than 1 register)
> +	 */
> +	u8 nr_registers;
> +	/* number of unique register banks */
> +	u8 nr_banks;
> +};
> +
> +static u8 register_bank(u16 reg)
> +{
> +	return reg >> 8;
> +}
> +
> +static u8 register_index(u16 reg)
> +{
> +	return reg & 0x00ff;
> +}
> +
> +static const struct ec_sensor_info *
> +get_sensor_info(const struct ec_sensors_data *state, int index)
> +{
> +	return &known_ec_sensors[state->sensors[index].info_index];
> +}
> +
> +static int find_ec_sensor_index(const struct ec_sensors_data *ec,
> +				enum hwmon_sensor_types type, int channel)
> +{
> +	unsigned int i;
> +
> +	for (i = 0; i < ec->nr_sensors; i++) {
> +		if (get_sensor_info(ec, i)->type == type) {
> +			if (channel == 0)
> +				return i;
> +			channel--;
> +		}
> +	}
> +	return -ENOENT;
> +}
> +
> +static int __init bank_compare(const void *a, const void *b)
> +{
> +	return *((const s8 *)a) - *((const s8 *)b);
> +}
> +
> +static int __init board_sensors_count(unsigned long sensors)
> +{
> +	return hweight_long(sensors);
> +}
> +
> +static void __init setup_sensor_data(struct ec_sensors_data *ec)
> +{
> +	struct ec_sensor *s = ec->sensors;
> +	bool bank_found;
> +	int i, j;
> +	u8 bank;
> +
> +	ec->nr_banks = 0;
> +	ec->nr_registers = 0;
> +
> +	for_each_set_bit(i, &ec->board_sensors,
> +			  BITS_PER_TYPE(ec->board_sensors)) {
> +		s->info_index = i;
> +		s->cached_value = 0;
> +		ec->nr_registers +=
> +			known_ec_sensors[s->info_index].addr.components.size;
> +		bank_found = false;
> +		bank = known_ec_sensors[s->info_index].addr.components.bank;
> +		for (j = 0; j < ec->nr_banks; j++) {
> +			if (ec->banks[j] == bank) {
> +				bank_found = true;
> +				break;
> +			}
> +		}
> +		if (!bank_found) {
> +			ec->banks[ec->nr_banks++] = bank;
> +		}
> +		s++;
> +	}
> +	sort(ec->banks, ec->nr_banks, 1, bank_compare, NULL);
> +}
> +
> +static void __init fill_ec_registers(struct ec_sensors_data *ec)
> +{
> +	const struct ec_sensor_info *si;
> +	unsigned int i, j, register_idx = 0;
> +
> +	for (i = 0; i < ec->nr_sensors; ++i) {
> +		si = get_sensor_info(ec, i);
> +		for (j = 0; j < si->addr.components.size; ++j, ++register_idx) {
> +			ec->registers[register_idx] =
> +				(si->addr.components.bank << 8) +
> +				si->addr.components.index + j;
> +		}
> +	}
> +}
> +
> +static acpi_handle __init asus_hw_access_mutex(struct device *dev)
> +{
> +	const char *mutex_path;
> +	acpi_handle res;
> +	int status;
> +
> +	mutex_path = mutex_path_override ?
> +		mutex_path_override : ASUS_HW_ACCESS_MUTEX_ASMX;
> +
> +	status = acpi_get_handle(NULL, (acpi_string)mutex_path, &res);
> +	if (ACPI_FAILURE(status)) {
> +		dev_err(dev,
> +			"Could not get hardware access guard mutex '%s': error %d",
> +			mutex_path, status);
> +		return NULL;
> +	}
> +	return res;
> +}
> +
> +static int asus_ec_bank_switch(u8 bank, u8 *old)
> +{
> +	int status = 0;
> +
> +	if (old) {
> +		status = ec_read(ASUS_EC_BANK_REGISTER, old);
> +	}
> +	if (status || (old && (*old == bank)))
> +		return status;
> +	return ec_write(ASUS_EC_BANK_REGISTER, bank);
> +}
> +
> +static int asus_ec_block_read(const struct device *dev,
> +			      struct ec_sensors_data *ec)
> +{
> +	int ireg, ibank, status;
> +	u8 bank, reg_bank, prev_bank;
> +
> +	bank = 0;
> +	status = asus_ec_bank_switch(bank, &prev_bank);
> +	if (status) {
> +		dev_warn(dev, "EC bank switch failed");
> +		return status;
> +	}
> +
> +	if (prev_bank) {
> +		/* oops... somebody else is working with the EC too */
> +		dev_warn(dev,
> +			"Concurrent access to the ACPI EC detected.\nRace condition possible.");
> +	}
> +
> +	/* read registers minimizing bank switches. */
> +	for (ibank = 0; ibank < ec->nr_banks; ibank++) {
> +		if (bank != ec->banks[ibank]) {
> +			bank = ec->banks[ibank];
> +			if (asus_ec_bank_switch(bank, NULL)) {
> +				dev_warn(dev, "EC bank switch to %d failed",
> +					 bank);
> +				break;
> +			}
> +		}
> +		for (ireg = 0; ireg < ec->nr_registers; ireg++) {
> +			reg_bank = register_bank(ec->registers[ireg]);
> +			if (reg_bank < bank) {
> +				continue;
> +			}
> +			ec_read(register_index(ec->registers[ireg]),
> +				ec->read_buffer + ireg);
> +		}
> +	}
> +
> +	status = asus_ec_bank_switch(prev_bank, NULL);
> +	return status;
> +}
> +
> +static inline u32 get_sensor_value(const struct ec_sensor_info *si, u8 *data)
> +{
> +	switch (si->addr.components.size) {
> +	case 1:
> +		return *data;
> +	case 2:
> +		return get_unaligned_be16(data);
> +	case 4:
> +		return get_unaligned_be32(data);
> +	default:
> +		return 0;
> +	}
> +}
> +
> +static void update_sensor_values(struct ec_sensors_data *ec, u8 *data)
> +{
> +	const struct ec_sensor_info *si;
> +	struct ec_sensor *s;
> +
> +	for (s = ec->sensors; s != ec->sensors + ec->nr_sensors; s++) {
> +		si = &known_ec_sensors[s->info_index];
> +		s->cached_value = get_sensor_value(si, data);
> +		data += si->addr.components.size;
> +	}
> +}
> +
> +static int update_ec_sensors(const struct device *dev,
> +			     struct ec_sensors_data *ec)
> +{
> +	int status;
> +
> +	/*
> +	 * ASUS DSDT does not specify that access to the EC has to be guarded,
> +	 * but firmware does access it via ACPI
> +	 */
> +	if (ACPI_FAILURE(acpi_acquire_mutex(ec->aml_mutex, NULL,
> +					    ACPI_LOCK_DELAY_MS))) {
> +		dev_err(dev, "Failed to acquire AML mutex");
> +		status = -EBUSY;
> +		goto cleanup;
> +	}
> +
> +	status = asus_ec_block_read(dev, ec);
> +
> +	if (!status) {
> +		update_sensor_values(ec, ec->read_buffer);
> +	}
> +	if (ACPI_FAILURE(acpi_release_mutex(ec->aml_mutex, NULL))) {
> +		dev_err(dev, "Failed to release AML mutex");
> +	}
> +cleanup:
> +	return status;
> +}
> +
> +static int scale_sensor_value(u32 value, int data_type)
> +{
> +	switch (data_type) {
> +	case hwmon_curr:
> +	case hwmon_temp:
> +	case hwmon_in:
> +		return value * MILLI;
> +	default:
> +		return value;
> +	}
> +}
> +
> +static int get_cached_value_or_update(const struct device *dev,
> +				      int sensor_index,
> +				      struct ec_sensors_data *state, u32 *value)
> +{
> +	if (time_after(jiffies, state->last_updated + HZ)) {
> +		if (update_ec_sensors(dev, state)) {
> +			dev_err(dev, "update_ec_sensors() failure\n");
> +			return -EIO;
> +		}
> +
> +		state->last_updated = jiffies;
> +	}
> +
> +	*value = state->sensors[sensor_index].cached_value;
> +	return 0;
> +}
> +
> +/*
> + * Now follow the functions that implement the hwmon interface
> + */
> +
> +static int asus_ec_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
> +			      u32 attr, int channel, long *val)
> +{
> +	int ret;
> +	u32 value = 0;
> +
> +	struct ec_sensors_data *state = dev_get_drvdata(dev);
> +	int sidx = find_ec_sensor_index(state, type, channel);
> +
> +	if (sidx < 0) {
> +		return sidx;
> +	}
> +
> +	ret = get_cached_value_or_update(dev, sidx, state, &value);
> +	if (!ret) {
> +		*val = scale_sensor_value(value,
> +					  get_sensor_info(state, sidx)->type);
> +	}
> +
> +	return ret;
> +}
> +
> +static int asus_ec_hwmon_read_string(struct device *dev,
> +				     enum hwmon_sensor_types type, u32 attr,
> +				     int channel, const char **str)
> +{
> +	struct ec_sensors_data *state = dev_get_drvdata(dev);
> +	int sensor_index = find_ec_sensor_index(state, type, channel);
> +	*str = get_sensor_info(state, sensor_index)->label;
> +
> +	return 0;
> +}
> +
> +static umode_t asus_ec_hwmon_is_visible(const void *drvdata,
> +					enum hwmon_sensor_types type, u32 attr,
> +					int channel)
> +{
> +	const struct ec_sensors_data *state = drvdata;
> +
> +	return find_ec_sensor_index(state, type, channel) >= 0 ? S_IRUGO : 0;
> +}
> +
> +static int __init
> +asus_ec_hwmon_add_chan_info(struct hwmon_channel_info *asus_ec_hwmon_chan,
> +			     struct device *dev, int num,
> +			     enum hwmon_sensor_types type, u32 config)
> +{
> +	int i;
> +	u32 *cfg = devm_kcalloc(dev, num + 1, sizeof(*cfg), GFP_KERNEL);
> +
> +	if (!cfg)
> +		return -ENOMEM;
> +
> +	asus_ec_hwmon_chan->type = type;
> +	asus_ec_hwmon_chan->config = cfg;
> +	for (i = 0; i < num; i++, cfg++)
> +		*cfg = config;
> +
> +	return 0;
> +}
> +
> +static const struct hwmon_ops asus_ec_hwmon_ops = {
> +	.is_visible = asus_ec_hwmon_is_visible,
> +	.read = asus_ec_hwmon_read,
> +	.read_string = asus_ec_hwmon_read_string,
> +};
> +
> +static struct hwmon_chip_info asus_ec_chip_info = {
> +	.ops = &asus_ec_hwmon_ops,
> +};
> +
> +static unsigned long __init
> +get_board_sensors(const struct device *dev)
> +{
> +	const struct dmi_system_id *dmi_entry;
> +
> +	dmi_entry = dmi_first_match(asus_ec_dmi_table);
> +	if (!dmi_entry) {
> +		dev_info(dev, "Unsupported board");
> +		return 0;
> +	}
> +
> +	return (unsigned long)dmi_entry->driver_data;
> +}
> +
> +static int __init configure_sensor_setup(struct device *dev)
> +{
> +	struct ec_sensors_data *ec_data = dev_get_drvdata(dev);
> +	int nr_count[hwmon_max] = { 0 }, nr_types = 0;
> +	struct device *hwdev;
> +	struct hwmon_channel_info *asus_ec_hwmon_chan;
> +	const struct hwmon_channel_info **ptr_asus_ec_ci;
> +	const struct hwmon_chip_info *chip_info;
> +	const struct ec_sensor_info *si;
> +	enum hwmon_sensor_types type;
> +	unsigned int i;
> +
> +	ec_data->board_sensors = get_board_sensors(dev);
> +	if (!ec_data->board_sensors) {
> +		return -ENODEV;
> +	}
> +
> +	ec_data->nr_sensors = board_sensors_count(ec_data->board_sensors);
> +	ec_data->sensors = devm_kcalloc(dev, ec_data->nr_sensors,
> +					sizeof(struct ec_sensor), GFP_KERNEL);
> +
> +	setup_sensor_data(ec_data);
> +	ec_data->registers = devm_kcalloc(dev, ec_data->nr_registers,
> +					  sizeof(u16), GFP_KERNEL);
> +	ec_data->read_buffer = devm_kcalloc(dev, ec_data->nr_registers,
> +					    sizeof(u8), GFP_KERNEL);
> +
> +	if (!ec_data->registers || !ec_data->read_buffer) {
> +		return -ENOMEM;
> +	}
> +
> +	fill_ec_registers(ec_data);
> +
> +	ec_data->aml_mutex = asus_hw_access_mutex(dev);
> +
> +	for (i = 0; i < ec_data->nr_sensors; ++i) {
> +		si = get_sensor_info(ec_data, i);
> +		if (!nr_count[si->type])
> +			++nr_types;
> +		++nr_count[si->type];
> +	}
> +
> +	if (nr_count[hwmon_temp])
> +		nr_count[hwmon_chip]++, nr_types++;
> +
> +	asus_ec_hwmon_chan = devm_kcalloc(
> +		dev, nr_types, sizeof(*asus_ec_hwmon_chan), GFP_KERNEL);
> +	if (!asus_ec_hwmon_chan)
> +		return -ENOMEM;
> +
> +	ptr_asus_ec_ci = devm_kcalloc(dev, nr_types + 1,
> +				       sizeof(*ptr_asus_ec_ci), GFP_KERNEL);
> +	if (!ptr_asus_ec_ci)
> +		return -ENOMEM;
> +
> +	asus_ec_chip_info.info = ptr_asus_ec_ci;
> +	chip_info = &asus_ec_chip_info;
> +
> +	for (type = 0; type < hwmon_max; ++type) {
> +		if (!nr_count[type])
> +			continue;
> +
> +		asus_ec_hwmon_add_chan_info(asus_ec_hwmon_chan, dev,
> +					     nr_count[type], type,
> +					     hwmon_attributes[type]);
> +		*ptr_asus_ec_ci++ = asus_ec_hwmon_chan++;
> +	}
> +
> +	dev_info(dev, "board has %d EC sensors that span %d registers",
> +		 ec_data->nr_sensors, ec_data->nr_registers);
> +
> +	hwdev = devm_hwmon_device_register_with_info(dev, "asusec",
> +						     ec_data, chip_info, NULL);
> +
> +	return PTR_ERR_OR_ZERO(hwdev);
> +}
> +
> +static int __init asus_ec_probe(struct platform_device *pdev)
> +{
> +	struct asus_ec_sensors *state;
> +	int status = 0;
> +
> +	state = devm_kzalloc(&pdev->dev, sizeof(struct ec_sensors_data),
> +			     GFP_KERNEL);
> +
> +	if (!state) {
> +		return -ENOMEM;
> +	}
> +
> +	dev_set_drvdata(&pdev->dev, state);
> +	status = configure_sensor_setup(&pdev->dev);
> +	return status;
> +}
> +
> +static const struct acpi_device_id acpi_ec_ids[] = {
> +	/* Embedded Controller Device */
> +	{ "PNP0C09", 0 },
> +	{}
> +};
> +
> +static struct platform_driver asus_ec_sensors_platform_driver = {
> +	.driver = {
> +		.name	= "asus-ec-sensors",
> +		.acpi_match_table = acpi_ec_ids,
> +	},
> +};
> +
> +MODULE_DEVICE_TABLE(dmi, asus_ec_dmi_table);
> +module_platform_driver_probe(asus_ec_sensors_platform_driver, asus_ec_probe);
> +
> +module_param_named(mutex_path, mutex_path_override, charp, 0);
> +MODULE_PARM_DESC(mutex_path,
> +		 "Override ACPI mutex path used to guard access to hardware");
> +
> +MODULE_AUTHOR("Eugene Shalygin <eugene.shalygin@...il.com>");
> +MODULE_DESCRIPTION(
> +	"HWMON driver for sensors accessible via ACPI EC in ASUS motherboards");
> +MODULE_LICENSE("GPL");
> 


-- 
Oleksandr Natalenko (post-factum)

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