hwmon: (core) 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 hwmon core. By using the new API,
driver code and data size is typically reduced by 20-70%, depending
on driver complexity and the number of sysfs attributes supported.

With this patch, the new API only supports thermal sensors. Support for
other sensor types will be added with subsequent patches.

Acked-by: Punit Agrawal <punit.agrawal@arm.com>
Reviewed-by: Jonathan Cameron <jic23@kernel.org>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 148 insertions, 0 deletions

diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
index 09354f6c1d63..52e56d71d742 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -14,9 +14,147 @@
 #ifndef _HWMON_H_
 #define _HWMON_H_
 
+#include <linux/bitops.h>
+
 struct device;
 struct attribute_group;
 
+enum hwmon_sensor_types {
+        hwmon_chip,
+        hwmon_temp,
+        hwmon_in,
+        hwmon_curr,
+        hwmon_power,
+        hwmon_energy,
+};
+
+enum hwmon_chip_attributes {
+        hwmon_chip_temp_reset_history,
+        hwmon_chip_register_tz,
+        hwmon_chip_update_interval,
+        hwmon_chip_alarms,
+};
+
+#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_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)
+
+enum hwmon_temp_attributes {
+        hwmon_temp_input = 0,
+        hwmon_temp_type,
+        hwmon_temp_lcrit,
+        hwmon_temp_lcrit_hyst,
+        hwmon_temp_min,
+        hwmon_temp_min_hyst,
+        hwmon_temp_max,
+        hwmon_temp_max_hyst,
+        hwmon_temp_crit,
+        hwmon_temp_crit_hyst,
+        hwmon_temp_emergency,
+        hwmon_temp_emergency_hyst,
+        hwmon_temp_alarm,
+        hwmon_temp_lcrit_alarm,
+        hwmon_temp_min_alarm,
+        hwmon_temp_max_alarm,
+        hwmon_temp_crit_alarm,
+        hwmon_temp_emergency_alarm,
+        hwmon_temp_fault,
+        hwmon_temp_offset,
+        hwmon_temp_label,
+        hwmon_temp_lowest,
+        hwmon_temp_highest,
+        hwmon_temp_reset_history,
+};
+
+#define HWMON_T_INPUT           BIT(hwmon_temp_input)
+#define HWMON_T_TYPE            BIT(hwmon_temp_type)
+#define HWMON_T_LCRIT           BIT(hwmon_temp_lcrit)
+#define HWMON_T_LCRIT_HYST      BIT(hwmon_temp_lcrit_hyst)
+#define HWMON_T_MIN             BIT(hwmon_temp_min)
+#define HWMON_T_MIN_HYST        BIT(hwmon_temp_min_hyst)
+#define HWMON_T_MAX             BIT(hwmon_temp_max)
+#define HWMON_T_MAX_HYST        BIT(hwmon_temp_max_hyst)
+#define HWMON_T_CRIT            BIT(hwmon_temp_crit)
+#define HWMON_T_CRIT_HYST       BIT(hwmon_temp_crit_hyst)
+#define HWMON_T_EMERGENCY       BIT(hwmon_temp_emergency)
+#define HWMON_T_EMERGENCY_HYST  BIT(hwmon_temp_emergency_hyst)
+#define HWMON_T_MIN_ALARM       BIT(hwmon_temp_min_alarm)
+#define HWMON_T_MAX_ALARM       BIT(hwmon_temp_max_alarm)
+#define HWMON_T_CRIT_ALARM      BIT(hwmon_temp_crit_alarm)
+#define HWMON_T_EMERGENCY_ALARM BIT(hwmon_temp_emergency_alarm)
+#define HWMON_T_FAULT           BIT(hwmon_temp_fault)
+#define HWMON_T_OFFSET          BIT(hwmon_temp_offset)
+#define HWMON_T_LABEL           BIT(hwmon_temp_label)
+#define HWMON_T_LOWEST          BIT(hwmon_temp_lowest)
+#define HWMON_T_HIGHEST         BIT(hwmon_temp_highest)
+#define HWMON_T_RESET_HISTORY   BIT(hwmon_temp_reset_history)
+
+/**
+ * struct hwmon_ops - hwmon device operations
+ * @is_visible: Callback to return attribute visibility. Mandatory.
+ *              Parameters are:
+ *              @const void *drvdata:
+ *                      Pointer to driver-private data structure passed
+ *                      as argument to hwmon_device_register_with_info().
+ *              @type:  Sensor type
+ *              @attr:  Sensor attribute
+ *              @channel:
+ *                      Channel number
+ *              The function returns the file permissions.
+ *              If the return value is 0, no attribute will be created.
+ * @read:       Read callback. Optional. If not provided, attributes
+ *              will not be readable.
+ *              Parameters are:
+ *              @dev:   Pointer to hardware monitoring device
+ *              @type:  Sensor type
+ *              @attr:  Sensor attribute
+ *              @channel:
+ *                      Channel number
+ *              @val:   Pointer to returned value
+ *              The function returns 0 on success or a negative error number.
+ * @write:      Write callback. Optional. If not provided, attributes
+ *              will not be writable.
+ *              Parameters are:
+ *              @dev:   Pointer to hardware monitoring device
+ *              @type:  Sensor type
+ *              @attr:  Sensor attribute
+ *              @channel:
+ *                      Channel number
+ *              @val:   Value to write
+ *              The function returns 0 on success or a negative error number.
+ */
+struct hwmon_ops {
+        umode_t (*is_visible)(const void *drvdata, enum hwmon_sensor_types type,
+                              u32 attr, int channel);
+        int (*read)(struct device *dev, enum hwmon_sensor_types type,
+                    u32 attr, int channel, long *val);
+        int (*write)(struct device *dev, enum hwmon_sensor_types type,
+                     u32 attr, int channel, long val);
+};
+
+/**
+ * Channel information
+ * @type:       Channel type.
+ * @config:     Pointer to NULL-terminated list of channel parameters.
+ *              Use for per-channel attributes.
+ */
+struct hwmon_channel_info {
+        enum hwmon_sensor_types type;
+        const u32 *config;
+};
+
+/**
+ * Chip configuration
+ * @ops:        Pointer to hwmon operations.
+ * @info:       Null-terminated list of channel information.
+ */
+struct hwmon_chip_info {
+        const struct hwmon_ops *ops;
+        const struct hwmon_channel_info **info;
+};
+
 struct device *hwmon_device_register(struct device *dev);
 struct device *
 hwmon_device_register_with_groups(struct device *dev, const char *name,
@@ -26,6 +164,16 @@ 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 **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);