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[PATCH v3 0/9] hwmon: New hwmon registration API

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  [PATCH v3 0/9] hwmon: New hwmon registration API Guenter Roeck <linux@roeck-us.net> - 2016-07-25 05:40 +0200
    [PATCH v3 8/9] hwmon: (core) Document new kernel API Guenter Roeck <linux@roeck-us.net> - 2016-07-25 05:40 +0200
    [PATCH v3 5/9] hwmon: (core) Add power attribute support to new API Guenter Roeck <linux@roeck-us.net> - 2016-07-25 05:40 +0200

#1449251 — [PATCH v3 0/9] hwmon: New hwmon registration API

Up to now, each hwmon driver has to implement its own sysfs attributes.
This requires a lot of template code, and distracts from the driver's
core function to read and write chip registers.

To be able to reduce driver complexity, move sensor attribute handling
and thermal zone registration into the hwmon core. By using the new API,
driver size is typically reduced by 20-50% depending on driver complexity
and the number of sysfs attributes supported.

The first patch of the series is preparatory; it reorders include files
in the hwmon core to make it easier to add or remove individual include
files.

The second patch of the series introduces the API as well as support
for temperature sensor attributes. Subsequent patches introduce support
for voltage, current, power, energy, humidity, fan speed, and basic pwm
attributes.

The series was tested by converting several drivers (lm75, lm90, tmp102,
tmp421, ltc4245, nct7904, max31790) to the new API. Testing was done with
real chips as well as with the hwmon driver module test code available
at https://github.com/groeck/module-tests.

v3:
- Thermal registration depends on IS_REACHABLE(CONFIG_THERMAL) and
  CONFIG_THERMAL_OF.
v2:
- Add patch 1/9 (order include files alphabetically).
- Add patch 9/9 (pwm support).
- Document callback function parameters of struct hwmon_ops in
  include/linux/hwmon.h.
- Clarify that the is_visible() callback is mandatory.
- If an attribute has no template string, treat it as invisible, not as
  error. Affected are virtual attributes such as HWMON_C_REGISTER_TZ.
- Initialize device attribute read/write callback functions unconditionally.
- Cosmetic changes, including typo fixes and added newlines for readability.

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#1449252 — [PATCH v3 8/9] hwmon: (core) Document new kernel API

Describe the new registration API function as well as the data
structures it requires.

Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v3: No change
v2: Fixed typos

 Documentation/hwmon/hwmon-kernel-api.txt | 229 ++++++++++++++++++++++++++++++-
 1 file changed, 227 insertions(+), 2 deletions(-)

diff --git a/Documentation/hwmon/hwmon-kernel-api.txt b/Documentation/hwmon/hwmon-kernel-api.txt
index 2ecdbfc85ecf..f60a29ce7592 100644
--- a/Documentation/hwmon/hwmon-kernel-api.txt
+++ b/Documentation/hwmon/hwmon-kernel-api.txt
@@ -34,6 +34,19 @@ 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 **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 **groups);
+
 void hwmon_device_unregister(struct device *dev);
 void devm_hwmon_device_unregister(struct device *dev);
 
@@ -60,15 +73,227 @@ 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.
+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 or with hwmon_device_register_with_groups.
+hwmon_device_register, 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.
+the call to devm_hwmon_device_register_with_groups and if the automatic
+(device managed) removal would be too late.
+
+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 **groups
+			Null-terminated list of additional 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 apply to the entire chip.
+  * 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
+
+* 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.
+
+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 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.
-- 
2.5.0

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#1449253 — [PATCH v3 5/9] hwmon: (core) Add power attribute support to new API

Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
v3: No change
v2: No change

 drivers/hwmon/hwmon.c | 30 ++++++++++++++++++++++++++++
 include/linux/hwmon.h | 54 +++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 84 insertions(+)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index 9229229a99a5..85f4e27548cb 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -261,6 +261,7 @@ static const char * const hwmon_chip_attr_templates[] = {
 	[hwmon_chip_temp_reset_history] = "temp_reset_history",
 	[hwmon_chip_in_reset_history] = "in_reset_history",
 	[hwmon_chip_curr_reset_history] = "curr_reset_history",
+	[hwmon_chip_power_reset_history] = "power_reset_history",
 	[hwmon_chip_update_interval] = "update_interval",
 	[hwmon_chip_alarms] = "alarms",
 };
@@ -328,11 +329,39 @@ static const char * const hwmon_curr_attr_templates[] = {
 	[hwmon_curr_crit_alarm] = "curr%d_crit_alarm",
 };
 
+static const char * const hwmon_power_attr_templates[] = {
+	[hwmon_power_average] = "power%d_average",
+	[hwmon_power_average_interval] = "power%d_average_interval",
+	[hwmon_power_average_interval_max] = "power%d_interval_max",
+	[hwmon_power_average_interval_min] = "power%d_interval_min",
+	[hwmon_power_average_highest] = "power%d_average_highest",
+	[hwmon_power_average_lowest] = "power%d_average_lowest",
+	[hwmon_power_average_max] = "power%d_average_max",
+	[hwmon_power_average_min] = "power%d_average_min",
+	[hwmon_power_input] = "power%d_input",
+	[hwmon_power_input_highest] = "power%d_input_highest",
+	[hwmon_power_input_lowest] = "power%d_input_lowest",
+	[hwmon_power_reset_history] = "power%d_reset_history",
+	[hwmon_power_accuracy] = "power%d_accuracy",
+	[hwmon_power_cap] = "power%d_cap",
+	[hwmon_power_cap_hyst] = "power%d_cap_hyst",
+	[hwmon_power_cap_max] = "power%d_cap_max",
+	[hwmon_power_cap_min] = "power%d_cap_min",
+	[hwmon_power_max] = "power%d_max",
+	[hwmon_power_crit] = "power%d_crit",
+	[hwmon_power_label] = "power%d_label",
+	[hwmon_power_alarm] = "power%d_alarm",
+	[hwmon_power_cap_alarm] = "power%d_cap_alarm",
+	[hwmon_power_max_alarm] = "power%d_max_alarm",
+	[hwmon_power_crit_alarm] = "power%d_crit_alarm",
+};
+
 static const char * const *__templates[] = {
 	[hwmon_chip] = hwmon_chip_attr_templates,
 	[hwmon_temp] = hwmon_temp_attr_templates,
 	[hwmon_in] = hwmon_in_attr_templates,
 	[hwmon_curr] = hwmon_curr_attr_templates,
+	[hwmon_power] = hwmon_power_attr_templates,
 };
 
 static const int __templates_size[] = {
@@ -340,6 +369,7 @@ static const int __templates_size[] = {
 	[hwmon_temp] = ARRAY_SIZE(hwmon_temp_attr_templates),
 	[hwmon_in] = ARRAY_SIZE(hwmon_in_attr_templates),
 	[hwmon_curr] = ARRAY_SIZE(hwmon_curr_attr_templates),
+	[hwmon_power] = ARRAY_SIZE(hwmon_power_attr_templates),
 };
 
 static int hwmon_num_channel_attrs(const struct hwmon_channel_info *info)
diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
index 8781c2253b1d..d7e432ef7c2a 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -32,6 +32,7 @@ enum hwmon_chip_attributes {
 	hwmon_chip_temp_reset_history,
 	hwmon_chip_in_reset_history,
 	hwmon_chip_curr_reset_history,
+	hwmon_chip_power_reset_history,
 	hwmon_chip_register_tz,
 	hwmon_chip_update_interval,
 	hwmon_chip_alarms,
@@ -40,6 +41,7 @@ enum hwmon_chip_attributes {
 #define HWMON_C_TEMP_RESET_HISTORY	BIT(hwmon_chip_temp_reset_history)
 #define HWMON_C_IN_RESET_HISTORY	BIT(hwmon_chip_in_reset_history)
 #define HWMON_C_CURR_RESET_HISTORY	BIT(hwmon_chip_curr_reset_history)
+#define HWMON_C_POWER_RESET_HISTORY	BIT(hwmon_chip_power_reset_history)
 #define HWMON_C_REGISTER_TZ		BIT(hwmon_chip_register_tz)
 #define HWMON_C_UPDATE_INTERVAL		BIT(hwmon_chip_update_interval)
 #define HWMON_C_ALARMS			BIT(hwmon_chip_alarms)
@@ -162,6 +164,58 @@ enum hwmon_curr_attributes {
 #define HWMON_C_LCRIT_ALARM	BIT(hwmon_curr_lcrit_alarm)
 #define HWMON_C_CRIT_ALARM	BIT(hwmon_curr_crit_alarm)
 
+enum hwmon_power_attributes {
+	hwmon_power_average,
+	hwmon_power_average_interval,
+	hwmon_power_average_interval_max,
+	hwmon_power_average_interval_min,
+	hwmon_power_average_highest,
+	hwmon_power_average_lowest,
+	hwmon_power_average_max,
+	hwmon_power_average_min,
+	hwmon_power_input,
+	hwmon_power_input_highest,
+	hwmon_power_input_lowest,
+	hwmon_power_reset_history,
+	hwmon_power_accuracy,
+	hwmon_power_cap,
+	hwmon_power_cap_hyst,
+	hwmon_power_cap_max,
+	hwmon_power_cap_min,
+	hwmon_power_max,
+	hwmon_power_crit,
+	hwmon_power_label,
+	hwmon_power_alarm,
+	hwmon_power_cap_alarm,
+	hwmon_power_max_alarm,
+	hwmon_power_crit_alarm,
+};
+
+#define HWMON_P_AVERAGE			BIT(hwmon_power_average)
+#define HWMON_P_AVERAGE_INTERVAL	BIT(hwmon_power_average_interval)
+#define HWMON_P_AVERAGE_INTERVAL_MAX	BIT(hwmon_power_average_interval_max)
+#define HWMON_P_AVERAGE_INTERVAL_MIN	BIT(hwmon_power_average_interval_min)
+#define HWMON_P_AVERAGE_HIGHEST		BIT(hwmon_power_average_highest)
+#define HWMON_P_AVERAGE_LOWEST		BIT(hwmon_power_average_lowest)
+#define HWMON_P_AVERAGE_MAX		BIT(hwmon_power_average_max)
+#define HWMON_P_AVERAGE_MIN		BIT(hwmon_power_average_min)
+#define HWMON_P_INPUT			BIT(hwmon_power_input)
+#define HWMON_P_INPUT_HIGHEST		BIT(hwmon_power_input_highest)
+#define HWMON_P_INPUT_LOWEST		BIT(hwmon_power_input_lowest)
+#define HWMON_P_RESET_HISTORY		BIT(hwmon_power_reset_history)
+#define HWMON_P_ACCURACY		BIT(hwmon_power_accuracy)
+#define HWMON_P_CAP			BIT(hwmon_power_cap)
+#define HWMON_P_CAP_HYST		BIT(hwmon_power_cap_hyst)
+#define HWMON_P_CAP_MAX			BIT(hwmon_power_cap_max)
+#define HWMON_P_CAP_MIN			BIT(hwmon_power_cap_min)
+#define HWMON_P_MAX			BIT(hwmon_power_max)
+#define HWMON_P_CRIT			BIT(hwmon_power_crit)
+#define HWMON_P_LABEL			BIT(hwmon_power_label)
+#define HWMON_P_ALARM			BIT(hwmon_power_alarm)
+#define HWMON_P_CAP_ALARM		BIT(hwmon_power_cap_alarm)
+#define HWMON_P_MAX_ALARM		BIT(hwmon_power_max_alarm)
+#define HWMON_P_CRIT_ALARM		BIT(hwmon_power_crit_alarm)
+
 /**
  * struct hwmon_ops - hwmon device operations
  * @is_visible: Callback to return attribute visibility. Mandatory.
-- 
2.5.0

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