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diff --git a/Documentation/hwmon/hwmon-kernel-api.txt b/Documentation/hwmon/hwmon-kernel-api.txt deleted file mode 100644 index 8bdefb41be30..000000000000 --- a/Documentation/hwmon/hwmon-kernel-api.txt +++ /dev/null @@ -1,341 +0,0 @@ -The Linux Hardware Monitoring kernel API. -========================================= - -Guenter Roeck - -Introduction ------------- - -This document describes the API that can be used by hardware monitoring -drivers that want to use the hardware monitoring framework. - -This document does not describe what a hardware monitoring (hwmon) Driver or -Device is. It also does not describe the API which can be used by user space -to communicate with a hardware monitoring device. If you want to know this -then please read the following file: Documentation/hwmon/sysfs-interface. - -For additional guidelines on how to write and improve hwmon drivers, please -also read Documentation/hwmon/submitting-patches. - -The API -------- -Each hardware monitoring driver must #include <linux/hwmon.h> and, in most -cases, <linux/hwmon-sysfs.h>. linux/hwmon.h declares the following -register/unregister functions: - -struct device * -hwmon_device_register_with_groups(struct device *dev, const char *name, - void *drvdata, - const struct attribute_group **groups); - -struct device * -devm_hwmon_device_register_with_groups(struct device *dev, - const char *name, void *drvdata, - const struct attribute_group **groups); - -struct device * -hwmon_device_register_with_info(struct device *dev, - const char *name, void *drvdata, - const struct hwmon_chip_info *info, - const struct attribute_group **extra_groups); - -struct device * -devm_hwmon_device_register_with_info(struct device *dev, - const char *name, - void *drvdata, - const struct hwmon_chip_info *info, - const struct attribute_group **extra_groups); - -void hwmon_device_unregister(struct device *dev); -void devm_hwmon_device_unregister(struct device *dev); - -hwmon_device_register_with_groups registers a hardware monitoring device. -The first parameter of this function is a pointer to the parent device. -The name parameter is a pointer to the hwmon device name. The registration -function wil create a name sysfs attribute pointing to this name. -The drvdata parameter is the pointer to the local driver data. -hwmon_device_register_with_groups will attach this pointer to the newly -allocated hwmon device. The pointer can be retrieved by the driver using -dev_get_drvdata() on the hwmon device pointer. The groups parameter is -a pointer to a list of sysfs attribute groups. The list must be NULL terminated. -hwmon_device_register_with_groups creates the hwmon device with name attribute -as well as all sysfs attributes attached to the hwmon device. -This function returns a pointer to the newly created hardware monitoring device -or PTR_ERR for failure. - -devm_hwmon_device_register_with_groups is similar to -hwmon_device_register_with_groups. However, it is device managed, meaning the -hwmon device does not have to be removed explicitly by the removal function. - -hwmon_device_register_with_info is the most comprehensive and preferred means -to register a hardware monitoring device. It creates the standard sysfs -attributes in the hardware monitoring core, letting the driver focus on reading -from and writing to the chip instead of having to bother with sysfs attributes. -The parent device parameter cannot be NULL with non-NULL chip info. Its -parameters are described in more detail below. - -devm_hwmon_device_register_with_info is similar to -hwmon_device_register_with_info. However, it is device managed, meaning the -hwmon device does not have to be removed explicitly by the removal function. - -hwmon_device_unregister deregisters a registered hardware monitoring device. -The parameter of this function is the pointer to the registered hardware -monitoring device structure. This function must be called from the driver -remove function if the hardware monitoring device was registered with -hwmon_device_register_with_groups or hwmon_device_register_with_info. - -devm_hwmon_device_unregister does not normally have to be called. It is only -needed for error handling, and only needed if the driver probe fails after -the call to devm_hwmon_device_register_with_groups or -hwmon_device_register_with_info and if the automatic (device managed) -removal would be too late. - -All supported hwmon device registration functions only accept valid device -names. Device names including invalid characters (whitespace, '*', or '-') -will be rejected. The 'name' parameter is mandatory. - -Using devm_hwmon_device_register_with_info() --------------------------------------------- - -hwmon_device_register_with_info() registers a hardware monitoring device. -The parameters to this function are - -struct device *dev Pointer to parent device -const char *name Device name -void *drvdata Driver private data -const struct hwmon_chip_info *info - Pointer to chip description. -const struct attribute_group **extra_groups - Null-terminated list of additional non-standard - sysfs attribute groups. - -This function returns a pointer to the created hardware monitoring device -on success and a negative error code for failure. - -The hwmon_chip_info structure looks as follows. - -struct hwmon_chip_info { - const struct hwmon_ops *ops; - const struct hwmon_channel_info **info; -}; - -It contains the following fields: - -* ops: Pointer to device operations. -* info: NULL-terminated list of device channel descriptors. - -The list of hwmon operations is defined as: - -struct hwmon_ops { - umode_t (*is_visible)(const void *, enum hwmon_sensor_types type, - u32 attr, int); - int (*read)(struct device *, enum hwmon_sensor_types type, - u32 attr, int, long *); - int (*write)(struct device *, enum hwmon_sensor_types type, - u32 attr, int, long); -}; - -It defines the following operations. - -* is_visible: Pointer to a function to return the file mode for each supported - attribute. This function is mandatory. - -* read: Pointer to a function for reading a value from the chip. This function - is optional, but must be provided if any readable attributes exist. - -* write: Pointer to a function for writing a value to the chip. This function is - optional, but must be provided if any writeable attributes exist. - -Each sensor channel is described with struct hwmon_channel_info, which is -defined as follows. - -struct hwmon_channel_info { - enum hwmon_sensor_types type; - u32 *config; -}; - -It contains following fields: - -* type: The hardware monitoring sensor type. - Supported sensor types are - * hwmon_chip A virtual sensor type, used to describe attributes - * which are not bound to a specific input or output - * hwmon_temp Temperature sensor - * hwmon_in Voltage sensor - * hwmon_curr Current sensor - * hwmon_power Power sensor - * hwmon_energy Energy sensor - * hwmon_humidity Humidity sensor - * hwmon_fan Fan speed sensor - * hwmon_pwm PWM control - -* config: Pointer to a 0-terminated list of configuration values for each - sensor of the given type. Each value is a combination of bit values - describing the attributes supposed by a single sensor. - -As an example, here is the complete description file for a LM75 compatible -sensor chip. The chip has a single temperature sensor. The driver wants to -register with the thermal subsystem (HWMON_C_REGISTER_TZ), and it supports -the update_interval attribute (HWMON_C_UPDATE_INTERVAL). The chip supports -reading the temperature (HWMON_T_INPUT), it has a maximum temperature -register (HWMON_T_MAX) as well as a maximum temperature hysteresis register -(HWMON_T_MAX_HYST). - -static const u32 lm75_chip_config[] = { - HWMON_C_REGISTER_TZ | HWMON_C_UPDATE_INTERVAL, - 0 -}; - -static const struct hwmon_channel_info lm75_chip = { - .type = hwmon_chip, - .config = lm75_chip_config, -}; - -static const u32 lm75_temp_config[] = { - HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_HYST, - 0 -}; - -static const struct hwmon_channel_info lm75_temp = { - .type = hwmon_temp, - .config = lm75_temp_config, -}; - -static const struct hwmon_channel_info *lm75_info[] = { - &lm75_chip, - &lm75_temp, - NULL -}; - -static const struct hwmon_ops lm75_hwmon_ops = { - .is_visible = lm75_is_visible, - .read = lm75_read, - .write = lm75_write, -}; - -static const struct hwmon_chip_info lm75_chip_info = { - .ops = &lm75_hwmon_ops, - .info = lm75_info, -}; - -A complete list of bit values indicating individual attribute support -is defined in include/linux/hwmon.h. Definition prefixes are as follows. - -HWMON_C_xxxx Chip attributes, for use with hwmon_chip. -HWMON_T_xxxx Temperature attributes, for use with hwmon_temp. -HWMON_I_xxxx Voltage attributes, for use with hwmon_in. -HWMON_C_xxxx Current attributes, for use with hwmon_curr. - Notice the prefix overlap with chip attributes. -HWMON_P_xxxx Power attributes, for use with hwmon_power. -HWMON_E_xxxx Energy attributes, for use with hwmon_energy. -HWMON_H_xxxx Humidity attributes, for use with hwmon_humidity. -HWMON_F_xxxx Fan speed attributes, for use with hwmon_fan. -HWMON_PWM_xxxx PWM control attributes, for use with hwmon_pwm. - -Driver callback functions -------------------------- - -Each driver provides is_visible, read, and write functions. Parameters -and return values for those functions are as follows. - -umode_t is_visible_func(const void *data, enum hwmon_sensor_types type, - u32 attr, int channel) - -Parameters: - data: Pointer to device private data structure. - type: The sensor type. - attr: Attribute identifier associated with a specific attribute. - For example, the attribute value for HWMON_T_INPUT would be - hwmon_temp_input. For complete mappings of bit fields to - attribute values please see include/linux/hwmon.h. - channel:The sensor channel number. - -Return value: - The file mode for this attribute. Typically, this will be 0 (the - attribute will not be created), S_IRUGO, or 'S_IRUGO | S_IWUSR'. - -int read_func(struct device *dev, enum hwmon_sensor_types type, - u32 attr, int channel, long *val) - -Parameters: - dev: Pointer to the hardware monitoring device. - type: The sensor type. - attr: Attribute identifier associated with a specific attribute. - For example, the attribute value for HWMON_T_INPUT would be - hwmon_temp_input. For complete mappings please see - include/linux/hwmon.h. - channel:The sensor channel number. - val: Pointer to attribute value. - -Return value: - 0 on success, a negative error number otherwise. - -int write_func(struct device *dev, enum hwmon_sensor_types type, - u32 attr, int channel, long val) - -Parameters: - dev: Pointer to the hardware monitoring device. - type: The sensor type. - attr: Attribute identifier associated with a specific attribute. - For example, the attribute value for HWMON_T_INPUT would be - hwmon_temp_input. For complete mappings please see - include/linux/hwmon.h. - channel:The sensor channel number. - val: The value to write to the chip. - -Return value: - 0 on success, a negative error number otherwise. - - -Driver-provided sysfs attributes --------------------------------- - -If the hardware monitoring device is registered with -hwmon_device_register_with_info or devm_hwmon_device_register_with_info, -it is most likely not necessary to provide sysfs attributes. Only additional -non-standard sysfs attributes need to be provided when one of those registration -functions is used. - -The header file linux/hwmon-sysfs.h provides a number of useful macros to -declare and use hardware monitoring sysfs attributes. - -In many cases, you can use the exsting define DEVICE_ATTR or its variants -DEVICE_ATTR_{RW,RO,WO} to declare such attributes. This is feasible if an -attribute has no additional context. However, in many cases there will be -additional information such as a sensor index which will need to be passed -to the sysfs attribute handling function. - -SENSOR_DEVICE_ATTR and SENSOR_DEVICE_ATTR_2 can be used to define attributes -which need such additional context information. SENSOR_DEVICE_ATTR requires -one additional argument, SENSOR_DEVICE_ATTR_2 requires two. - -Simplified variants of SENSOR_DEVICE_ATTR and SENSOR_DEVICE_ATTR_2 are available -and should be used if standard attribute permissions and function names are -feasible. Standard permissions are 0644 for SENSOR_DEVICE_ATTR[_2]_RW, -0444 for SENSOR_DEVICE_ATTR[_2]_RO, and 0200 for SENSOR_DEVICE_ATTR[_2]_WO. -Standard functions, similar to DEVICE_ATTR_{RW,RO,WO}, have _show and _store -appended to the provided function name. - -SENSOR_DEVICE_ATTR and its variants define a struct sensor_device_attribute -variable. This structure has the following fields. - -struct sensor_device_attribute { - struct device_attribute dev_attr; - int index; -}; - -You can use to_sensor_dev_attr to get the pointer to this structure from the -attribute read or write function. Its parameter is the device to which the -attribute is attached. - -SENSOR_DEVICE_ATTR_2 and its variants define a struct sensor_device_attribute_2 -variable, which is defined as follows. - -struct sensor_device_attribute_2 { - struct device_attribute dev_attr; - u8 index; - u8 nr; -}; - -Use to_sensor_dev_attr_2 to get the pointer to this structure. Its parameter -is the device to which the attribute is attached. |