[PATCH 0/5] hwmon: New hwmon registration API

[PATCH 0/5] hwmon: New hwmon registration API

[Guenter Roeck]

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 introduces the API as well as support
for temperature sensors. Subsequent patches introduce support for
voltage, current, power, energy, humidity, and fan speed sensors.

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

[PATCH 1/7] hwmon: (core) New hwmon registration API

[Guenter Roeck]

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 size is typically reduced by 20-50% 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.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/hwmon.c | 485 ++++++++++++++++++++++++++++++++++++++++++++++----
 include/linux/hwmon.h | 122 +++++++++++++
 2 files changed, 574 insertions(+), 33 deletions(-)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index a26c385a435b..9530644ae297 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -12,17 +12,16 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-#include <linux/module.h>
+#include <linux/bitops.h>
 #include <linux/device.h>
 #include <linux/err.h>
-#include <linux/slab.h>
-#include <linux/kdev_t.h>
-#include <linux/idr.h>
 #include <linux/hwmon.h>
-#include <linux/gfp.h>
-#include <linux/spinlock.h>
+#include <linux/idr.h>
+#include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/thermal.h>
 
 #define HWMON_ID_PREFIX "hwmon"
 #define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
@@ -30,9 +29,33 @@
 struct hwmon_device {
 	const char *name;
 	struct device dev;
+	const struct hwmon_chip_info *chip;
+
+	struct attribute_group group;
+	const struct attribute_group **groups;
 };
 #define to_hwmon_device(d) container_of(d, struct hwmon_device, dev)
 
+struct hwmon_device_attribute {
+	struct device_attribute dev_attr;
+	const struct hwmon_ops *ops;
+	enum hwmon_sensor_types type;
+	u32 attr;
+	int index;
+};
+#define to_hwmon_attr(d) \
+	container_of(d, struct hwmon_device_attribute, dev_attr)
+
+/*
+ * Thermal zone information
+ * In addition to the reference to the hwmon device,
+ * also provides the sensor index.
+ */
+struct hwmon_thermal_data {
+	struct hwmon_device *hwdev;	/* Reference to hwmon device */
+	int index;			/* sensor index */
+};
+
 static ssize_t
 show_name(struct device *dev, struct device_attribute *attr, char *buf)
 {
@@ -80,25 +103,280 @@ static struct class hwmon_class = {
 
 static DEFINE_IDA(hwmon_ida);
 
-/**
- * hwmon_device_register_with_groups - register w/ hwmon
- * @dev: the parent device
- * @name: hwmon name attribute
- * @drvdata: driver data to attach to created device
- * @groups: List of attribute groups to create
- *
- * hwmon_device_unregister() must be called when the device is no
- * longer needed.
- *
- * Returns the pointer to the new device.
- */
-struct device *
-hwmon_device_register_with_groups(struct device *dev, const char *name,
-				  void *drvdata,
-				  const struct attribute_group **groups)
+/* Thermal zone handling */
+
+static int hwmon_thermal_get_temp(void *data, int *temp)
+{
+	struct hwmon_thermal_data *tdata = data;
+	struct hwmon_device *hwdev = tdata->hwdev;
+	int ret;
+	long t;
+
+	ret = hwdev->chip->ops->read(&hwdev->dev, hwmon_temp, hwmon_temp_input,
+				     tdata->index, &t);
+	if (ret < 0)
+		return ret;
+
+	*temp = t;
+
+	return 0;
+}
+
+static struct thermal_zone_of_device_ops hwmon_thermal_ops = {
+	.get_temp = hwmon_thermal_get_temp,
+};
+
+static int hwmon_thermal_add_sensor(struct device *dev,
+				    struct hwmon_device *hwdev,
+				    int index)
+{
+	struct hwmon_thermal_data *tdata;
+
+	tdata = devm_kzalloc(dev, sizeof(*tdata), GFP_KERNEL);
+	if (!tdata)
+		return -ENOMEM;
+
+	tdata->hwdev = hwdev;
+	tdata->index = index;
+
+	devm_thermal_zone_of_sensor_register(&hwdev->dev, index, tdata,
+					     &hwmon_thermal_ops);
+
+	return 0;
+}
+
+/* sysfs attribute management */
+
+static ssize_t hwmon_attr_show(struct device *dev,
+			       struct device_attribute *devattr, char *buf)
+{
+	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
+	long val;
+	int ret;
+
+	ret = hattr->ops->read(dev, hattr->type, hattr->attr, hattr->index,
+			       &val);
+	if (ret < 0)
+		return ret;
+
+	return sprintf(buf, "%ld\n", val);
+}
+
+static ssize_t hwmon_attr_store(struct device *dev,
+				struct device_attribute *devattr,
+				const char *buf, size_t count)
+{
+	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
+	long val;
+	int ret;
+
+	ret = kstrtol(buf, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	ret = hattr->ops->write(dev, hattr->type, hattr->attr, hattr->index,
+				val);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static int hwmon_attr_base(enum hwmon_sensor_types type)
+{
+	if (type == hwmon_in)
+		return 0;
+	return 1;
+}
+
+static struct attribute *hwmon_genattr(struct device *dev,
+				       const void *drvdata,
+				       enum hwmon_sensor_types type,
+				       u32 attr,
+				       int index,
+				       const char *template,
+				       const struct hwmon_ops *ops)
+{
+	struct hwmon_device_attribute *hattr;
+	struct device_attribute *dattr;
+	struct attribute *a;
+	umode_t mode;
+	char *name;
+
+	if (!template)
+		return ERR_PTR(-EINVAL);
+
+	mode = ops->is_visible(drvdata, type, attr, index);
+	if (!mode)
+		return ERR_PTR(-ENOENT);
+
+	if ((mode & S_IRUGO) && !ops->read)
+		return ERR_PTR(-EINVAL);
+	if ((mode & S_IWUGO) && !ops->write)
+		return ERR_PTR(-EINVAL);
+
+	if (type == hwmon_chip) {
+		name = (char *)template;
+	} else {
+		name = devm_kzalloc(dev, strlen(template) + 16, GFP_KERNEL);
+		if (!name)
+			return ERR_PTR(-ENOMEM);
+		scnprintf(name, strlen(template) + 16, template,
+			  index + hwmon_attr_base(type));
+	}
+
+	hattr = devm_kzalloc(dev, sizeof(*hattr), GFP_KERNEL);
+	if (!hattr)
+		return ERR_PTR(-ENOMEM);
+
+	hattr->type = type;
+	hattr->attr = attr;
+	hattr->index = index;
+	hattr->ops = ops;
+
+	dattr = &hattr->dev_attr;
+	if (mode & S_IRUGO)
+		dattr->show = hwmon_attr_show;
+	if (mode & S_IWUGO)
+		dattr->store = hwmon_attr_store;
+
+	a = &dattr->attr;
+	sysfs_attr_init(a);
+	a->name = name;
+	a->mode = mode;
+
+	return a;
+}
+
+static const char * const hwmon_chip_attr_templates[] = {
+	[hwmon_chip_temp_reset_history] = "temp_reset_history",
+	[hwmon_chip_update_interval] = "update_interval",
+	[hwmon_chip_alarms] = "alarms",
+};
+
+static const char * const hwmon_temp_attr_templates[] = {
+	[hwmon_temp_input] = "temp%d_input",
+	[hwmon_temp_type] = "temp%d_type",
+	[hwmon_temp_lcrit] = "temp%d_lcrit",
+	[hwmon_temp_lcrit_hyst] = "temp%d_lcrit_hyst",
+	[hwmon_temp_min] = "temp%d_min",
+	[hwmon_temp_min_hyst] = "temp%d_min_hyst",
+	[hwmon_temp_max] = "temp%d_max",
+	[hwmon_temp_max_hyst] = "temp%d_max_hyst",
+	[hwmon_temp_crit] = "temp%d_crit",
+	[hwmon_temp_crit_hyst] = "temp%d_crit_hyst",
+	[hwmon_temp_emergency] = "temp%d_emergency",
+	[hwmon_temp_emergency_hyst] = "temp%d_emergency_hyst",
+	[hwmon_temp_alarm] = "temp%d_alarm",
+	[hwmon_temp_lcrit_alarm] = "temp%d_lcrit_alarm",
+	[hwmon_temp_min_alarm] = "temp%d_min_alarm",
+	[hwmon_temp_max_alarm] = "temp%d_max_alarm",
+	[hwmon_temp_crit_alarm] = "temp%d_crit_alarm",
+	[hwmon_temp_emergency_alarm] = "temp%d_emergency_alarm",
+	[hwmon_temp_fault] = "temp%d_fault",
+	[hwmon_temp_offset] = "temp%d_offset",
+	[hwmon_temp_label] = "temp%d_label",
+	[hwmon_temp_lowest] = "temp%d_lowest",
+	[hwmon_temp_highest] = "temp%d_highest",
+	[hwmon_temp_reset_history] = "temp%d_reset_history",
+};
+
+static const char * const *__templates[] = {
+	[hwmon_chip] = hwmon_chip_attr_templates,
+	[hwmon_temp] = hwmon_temp_attr_templates,
+};
+
+static const int __templates_size[] = {
+	[hwmon_chip] = ARRAY_SIZE(hwmon_chip_attr_templates),
+	[hwmon_temp] = ARRAY_SIZE(hwmon_temp_attr_templates),
+};
+
+static int hwmon_num_channel_attrs(const struct hwmon_channel_info *info)
+{
+	int i, n;
+
+	for (i = n = 0; info->config[i]; i++)
+		n += hweight32(info->config[i]);
+
+	return n;
+}
+
+static int hwmon_genattrs(struct device *dev,
+			  const void *drvdata,
+			  struct attribute **attrs,
+			  const struct hwmon_ops *ops,
+			  const struct hwmon_channel_info *info)
+{
+	const char * const *templates;
+	int template_size;
+	int i, aindex = 0;
+
+	if (info->type >= ARRAY_SIZE(__templates))
+		return -EINVAL;
+
+	templates = __templates[info->type];
+	template_size = __templates_size[info->type];
+
+	for (i = 0; info->config[i]; i++) {
+		u32 attr_mask = info->config[i];
+		u32 attr;
+
+		while (attr_mask) {
+			struct attribute *a;
+
+			attr = __ffs(attr_mask);
+			attr_mask &= ~BIT(attr);
+			if (attr >= template_size)
+				return -EINVAL;
+			a = hwmon_genattr(dev, drvdata, info->type, attr, i,
+					  templates[attr], ops);
+			if (IS_ERR(a)) {
+				if (PTR_ERR(a) != -ENOENT)
+					return PTR_ERR(a);
+				continue;
+			}
+			attrs[aindex++] = a;
+		}
+	}
+	return aindex;
+}
+
+static struct attribute **
+__hwmon_create_attrs(struct device *dev, const void *drvdata,
+		     const struct hwmon_chip_info *chip)
+{
+	int ret, i, aindex = 0, nattrs = 0;
+	struct attribute **attrs;
+
+	for (i = 0; chip->info[i]; i++)
+		nattrs += hwmon_num_channel_attrs(chip->info[i]);
+
+	if (nattrs == 0)
+		return ERR_PTR(-EINVAL);
+
+	attrs = devm_kcalloc(dev, nattrs + 1, sizeof(*attrs), GFP_KERNEL);
+	if (attrs == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; chip->info[i]; i++) {
+		ret = hwmon_genattrs(dev, drvdata, &attrs[aindex], chip->ops,
+				     chip->info[i]);
+		if (ret < 0)
+			return ERR_PTR(ret);
+		aindex += ret;
+	}
+
+	return attrs;
+}
+
+static struct device *
+__hwmon_device_register(struct device *dev, const char *name, void *drvdata,
+			const struct hwmon_chip_info *chip,
+			const struct attribute_group **groups)
 {
 	struct hwmon_device *hwdev;
-	int err, id;
+	struct device *hdev;
+	int i, j, err, id;
 
 	/* Do not accept invalid characters in hwmon name attribute */
 	if (name && (!strlen(name) || strpbrk(name, "-* \t\n")))
@@ -114,28 +392,128 @@ hwmon_device_register_with_groups(struct device *dev, const char *name,
 		goto ida_remove;
 	}
 
+	hdev = &hwdev->dev;
+
+	if (chip && chip->ops->is_visible) {
+		struct attribute **attrs;
+		int ngroups = 2;
+
+		if (groups)
+			for (i = 0; groups[i]; i++)
+				ngroups++;
+
+		hwdev->groups = devm_kcalloc(dev, ngroups, sizeof(*groups),
+					     GFP_KERNEL);
+		if (hwdev->groups == NULL)
+			return ERR_PTR(-ENOMEM);
+
+		attrs = __hwmon_create_attrs(dev, drvdata, chip);
+		if (IS_ERR(attrs)) {
+			err = PTR_ERR(attrs);
+			goto free_hwmon;
+		}
+
+		hwdev->group.attrs = attrs;
+		ngroups = 0;
+		hwdev->groups[ngroups++] = &hwdev->group;
+
+		if (groups) {
+			for (i = 0; groups[i]; i++)
+				hwdev->groups[ngroups++] = groups[i];
+		}
+
+		hdev->groups = hwdev->groups;
+	} else {
+		hdev->groups = groups;
+	}
+
 	hwdev->name = name;
-	hwdev->dev.class = &hwmon_class;
-	hwdev->dev.parent = dev;
-	hwdev->dev.groups = groups;
-	hwdev->dev.of_node = dev ? dev->of_node : NULL;
-	dev_set_drvdata(&hwdev->dev, drvdata);
-	dev_set_name(&hwdev->dev, HWMON_ID_FORMAT, id);
-	err = device_register(&hwdev->dev);
+	hdev->class = &hwmon_class;
+	hdev->parent = dev;
+	hdev->of_node = dev ? dev->of_node : NULL;
+	hwdev->chip = chip;
+	dev_set_drvdata(hdev, drvdata);
+	dev_set_name(hdev, HWMON_ID_FORMAT, id);
+	err = device_register(hdev);
 	if (err)
-		goto free;
+		goto free_hwmon;
+
+	if (chip && chip->ops->is_visible && chip->ops->read &&
+	    chip->info[0]->type == hwmon_chip &&
+	    (chip->info[0]->config[0] & HWMON_C_REGISTER_TZ)) {
+		const struct hwmon_channel_info **info = chip->info;
+
+		for (i = 1; info[i]; i++) {
+			if (info[i]->type != hwmon_temp)
+				continue;
+
+			for (j = 0; info[i]->config[j]; j++) {
+				if (!chip->ops->is_visible(drvdata, hwmon_temp,
+							   hwmon_temp_input, j))
+					continue;
+				if (info[i]->config[j] & HWMON_T_INPUT)
+					hwmon_thermal_add_sensor(dev, hwdev, j);
+			}
+		}
+	}
 
-	return &hwdev->dev;
+	return hdev;
 
-free:
+free_hwmon:
 	kfree(hwdev);
 ida_remove:
 	ida_simple_remove(&hwmon_ida, id);
 	return ERR_PTR(err);
 }
+
+/**
+ * hwmon_device_register_with_groups - register w/ hwmon
+ * @dev: the parent device
+ * @name: hwmon name attribute
+ * @drvdata: driver data to attach to created device
+ * @groups: List of attribute groups to create
+ *
+ * hwmon_device_unregister() must be called when the device is no
+ * longer needed.
+ *
+ * Returns the pointer to the new device.
+ */
+struct device *
+hwmon_device_register_with_groups(struct device *dev, const char *name,
+				  void *drvdata,
+				  const struct attribute_group **groups)
+{
+	return __hwmon_device_register(dev, name, drvdata, NULL, groups);
+}
 EXPORT_SYMBOL_GPL(hwmon_device_register_with_groups);
 
 /**
+ * hwmon_device_register_with_info - register w/ hwmon
+ * @dev: the parent device
+ * @name: hwmon name attribute
+ * @drvdata: driver data to attach to created device
+ * @info: Pointer to hwmon chip information
+ * @groups - pointer to list of driver specific attribute groups
+ *
+ * hwmon_device_unregister() must be called when the device is no
+ * longer needed.
+ *
+ * Returns the pointer to the new device.
+ */
+struct device *
+hwmon_device_register_with_info(struct device *dev, const char *name,
+				  void *drvdata,
+				  const struct hwmon_chip_info *chip,
+				  const struct attribute_group **groups)
+{
+	if (chip && (!chip->ops || !chip->info))
+		return ERR_PTR(-EINVAL);
+
+	return __hwmon_device_register(dev, name, drvdata, chip, groups);
+}
+EXPORT_SYMBOL_GPL(hwmon_device_register_with_info);
+
+/**
  * hwmon_device_register - register w/ hwmon
  * @dev: the device to register
  *
@@ -213,6 +591,47 @@ error:
 }
 EXPORT_SYMBOL_GPL(devm_hwmon_device_register_with_groups);
 
+/**
+ * devm_hwmon_device_register_with_info - register w/ hwmon
+ * @dev: the parent device
+ * @name: hwmon name attribute
+ * @drvdata: driver data to attach to created device
+ * @info: Pointer to hwmon chip information
+ * @groups - pointer to list of driver specific attribute groups
+ *
+ * Returns the pointer to the new device. The new device is automatically
+ * unregistered with the parent device.
+ */
+struct device *
+devm_hwmon_device_register_with_info(struct device *dev, const char *name,
+				     void *drvdata,
+				     const struct hwmon_chip_info *chip,
+				     const struct attribute_group **groups)
+{
+	struct device **ptr, *hwdev;
+
+	if (!dev)
+		return ERR_PTR(-EINVAL);
+
+	ptr = devres_alloc(devm_hwmon_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	hwdev = hwmon_device_register_with_info(dev, name, drvdata, chip,
+						groups);
+	if (IS_ERR(hwdev))
+		goto error;
+
+	*ptr = hwdev;
+	devres_add(dev, ptr);
+	return hwdev;
+
+error:
+	devres_free(ptr);
+	return hwdev;
+}
+EXPORT_SYMBOL_GPL(devm_hwmon_device_register_with_info);
+
 static int devm_hwmon_match(struct device *dev, void *res, void *data)
 {
 	struct device **hwdev = res;
diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
index 09354f6c1d63..99250ad092fd 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -14,9 +14,121 @@
 #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.
+ *		Optional.
+ * @read:       Read callback. Optional.
+ * @write:	Write callback. Optional.
+ */
+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);
+};
+
+/**
+ * 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 +138,16 @@ 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);
-- 
2.5.0

[PATCH 1/7] hwmon: (core) New hwmon registration API

[Guenter Roeck]

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 size is typically reduced by 20-50% 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.

Signed-off-by: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
---
 drivers/hwmon/hwmon.c | 485 ++++++++++++++++++++++++++++++++++++++++++++++----
 include/linux/hwmon.h | 122 +++++++++++++
 2 files changed, 574 insertions(+), 33 deletions(-)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index a26c385a435b..9530644ae297 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -12,17 +12,16 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
-#include <linux/module.h>
+#include <linux/bitops.h>
 #include <linux/device.h>
 #include <linux/err.h>
-#include <linux/slab.h>
-#include <linux/kdev_t.h>
-#include <linux/idr.h>
 #include <linux/hwmon.h>
-#include <linux/gfp.h>
-#include <linux/spinlock.h>
+#include <linux/idr.h>
+#include <linux/module.h>
 #include <linux/pci.h>
+#include <linux/slab.h>
 #include <linux/string.h>
+#include <linux/thermal.h>
 
 #define HWMON_ID_PREFIX "hwmon"
 #define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
@@ -30,9 +29,33 @@
 struct hwmon_device {
 	const char *name;
 	struct device dev;
+	const struct hwmon_chip_info *chip;
+
+	struct attribute_group group;
+	const struct attribute_group **groups;
 };
 #define to_hwmon_device(d) container_of(d, struct hwmon_device, dev)
 
+struct hwmon_device_attribute {
+	struct device_attribute dev_attr;
+	const struct hwmon_ops *ops;
+	enum hwmon_sensor_types type;
+	u32 attr;
+	int index;
+};
+#define to_hwmon_attr(d) \
+	container_of(d, struct hwmon_device_attribute, dev_attr)
+
+/*
+ * Thermal zone information
+ * In addition to the reference to the hwmon device,
+ * also provides the sensor index.
+ */
+struct hwmon_thermal_data {
+	struct hwmon_device *hwdev;	/* Reference to hwmon device */
+	int index;			/* sensor index */
+};
+
 static ssize_t
 show_name(struct device *dev, struct device_attribute *attr, char *buf)
 {
@@ -80,25 +103,280 @@ static struct class hwmon_class = {
 
 static DEFINE_IDA(hwmon_ida);
 
-/**
- * hwmon_device_register_with_groups - register w/ hwmon
- * @dev: the parent device
- * @name: hwmon name attribute
- * @drvdata: driver data to attach to created device
- * @groups: List of attribute groups to create
- *
- * hwmon_device_unregister() must be called when the device is no
- * longer needed.
- *
- * Returns the pointer to the new device.
- */
-struct device *
-hwmon_device_register_with_groups(struct device *dev, const char *name,
-				  void *drvdata,
-				  const struct attribute_group **groups)
+/* Thermal zone handling */
+
+static int hwmon_thermal_get_temp(void *data, int *temp)
+{
+	struct hwmon_thermal_data *tdata = data;
+	struct hwmon_device *hwdev = tdata->hwdev;
+	int ret;
+	long t;
+
+	ret = hwdev->chip->ops->read(&hwdev->dev, hwmon_temp, hwmon_temp_input,
+				     tdata->index, &t);
+	if (ret < 0)
+		return ret;
+
+	*temp = t;
+
+	return 0;
+}
+
+static struct thermal_zone_of_device_ops hwmon_thermal_ops = {
+	.get_temp = hwmon_thermal_get_temp,
+};
+
+static int hwmon_thermal_add_sensor(struct device *dev,
+				    struct hwmon_device *hwdev,
+				    int index)
+{
+	struct hwmon_thermal_data *tdata;
+
+	tdata = devm_kzalloc(dev, sizeof(*tdata), GFP_KERNEL);
+	if (!tdata)
+		return -ENOMEM;
+
+	tdata->hwdev = hwdev;
+	tdata->index = index;
+
+	devm_thermal_zone_of_sensor_register(&hwdev->dev, index, tdata,
+					     &hwmon_thermal_ops);
+
+	return 0;
+}
+
+/* sysfs attribute management */
+
+static ssize_t hwmon_attr_show(struct device *dev,
+			       struct device_attribute *devattr, char *buf)
+{
+	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
+	long val;
+	int ret;
+
+	ret = hattr->ops->read(dev, hattr->type, hattr->attr, hattr->index,
+			       &val);
+	if (ret < 0)
+		return ret;
+
+	return sprintf(buf, "%ld\n", val);
+}
+
+static ssize_t hwmon_attr_store(struct device *dev,
+				struct device_attribute *devattr,
+				const char *buf, size_t count)
+{
+	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
+	long val;
+	int ret;
+
+	ret = kstrtol(buf, 10, &val);
+	if (ret < 0)
+		return ret;
+
+	ret = hattr->ops->write(dev, hattr->type, hattr->attr, hattr->index,
+				val);
+	if (ret < 0)
+		return ret;
+
+	return count;
+}
+
+static int hwmon_attr_base(enum hwmon_sensor_types type)
+{
+	if (type == hwmon_in)
+		return 0;
+	return 1;
+}
+
+static struct attribute *hwmon_genattr(struct device *dev,
+				       const void *drvdata,
+				       enum hwmon_sensor_types type,
+				       u32 attr,
+				       int index,
+				       const char *template,
+				       const struct hwmon_ops *ops)
+{
+	struct hwmon_device_attribute *hattr;
+	struct device_attribute *dattr;
+	struct attribute *a;
+	umode_t mode;
+	char *name;
+
+	if (!template)
+		return ERR_PTR(-EINVAL);
+
+	mode = ops->is_visible(drvdata, type, attr, index);
+	if (!mode)
+		return ERR_PTR(-ENOENT);
+
+	if ((mode & S_IRUGO) && !ops->read)
+		return ERR_PTR(-EINVAL);
+	if ((mode & S_IWUGO) && !ops->write)
+		return ERR_PTR(-EINVAL);
+
+	if (type == hwmon_chip) {
+		name = (char *)template;
+	} else {
+		name = devm_kzalloc(dev, strlen(template) + 16, GFP_KERNEL);
+		if (!name)
+			return ERR_PTR(-ENOMEM);
+		scnprintf(name, strlen(template) + 16, template,
+			  index + hwmon_attr_base(type));
+	}
+
+	hattr = devm_kzalloc(dev, sizeof(*hattr), GFP_KERNEL);
+	if (!hattr)
+		return ERR_PTR(-ENOMEM);
+
+	hattr->type = type;
+	hattr->attr = attr;
+	hattr->index = index;
+	hattr->ops = ops;
+
+	dattr = &hattr->dev_attr;
+	if (mode & S_IRUGO)
+		dattr->show = hwmon_attr_show;
+	if (mode & S_IWUGO)
+		dattr->store = hwmon_attr_store;
+
+	a = &dattr->attr;
+	sysfs_attr_init(a);
+	a->name = name;
+	a->mode = mode;
+
+	return a;
+}
+
+static const char * const hwmon_chip_attr_templates[] = {
+	[hwmon_chip_temp_reset_history] = "temp_reset_history",
+	[hwmon_chip_update_interval] = "update_interval",
+	[hwmon_chip_alarms] = "alarms",
+};
+
+static const char * const hwmon_temp_attr_templates[] = {
+	[hwmon_temp_input] = "temp%d_input",
+	[hwmon_temp_type] = "temp%d_type",
+	[hwmon_temp_lcrit] = "temp%d_lcrit",
+	[hwmon_temp_lcrit_hyst] = "temp%d_lcrit_hyst",
+	[hwmon_temp_min] = "temp%d_min",
+	[hwmon_temp_min_hyst] = "temp%d_min_hyst",
+	[hwmon_temp_max] = "temp%d_max",
+	[hwmon_temp_max_hyst] = "temp%d_max_hyst",
+	[hwmon_temp_crit] = "temp%d_crit",
+	[hwmon_temp_crit_hyst] = "temp%d_crit_hyst",
+	[hwmon_temp_emergency] = "temp%d_emergency",
+	[hwmon_temp_emergency_hyst] = "temp%d_emergency_hyst",
+	[hwmon_temp_alarm] = "temp%d_alarm",
+	[hwmon_temp_lcrit_alarm] = "temp%d_lcrit_alarm",
+	[hwmon_temp_min_alarm] = "temp%d_min_alarm",
+	[hwmon_temp_max_alarm] = "temp%d_max_alarm",
+	[hwmon_temp_crit_alarm] = "temp%d_crit_alarm",
+	[hwmon_temp_emergency_alarm] = "temp%d_emergency_alarm",
+	[hwmon_temp_fault] = "temp%d_fault",
+	[hwmon_temp_offset] = "temp%d_offset",
+	[hwmon_temp_label] = "temp%d_label",
+	[hwmon_temp_lowest] = "temp%d_lowest",
+	[hwmon_temp_highest] = "temp%d_highest",
+	[hwmon_temp_reset_history] = "temp%d_reset_history",
+};
+
+static const char * const *__templates[] = {
+	[hwmon_chip] = hwmon_chip_attr_templates,
+	[hwmon_temp] = hwmon_temp_attr_templates,
+};
+
+static const int __templates_size[] = {
+	[hwmon_chip] = ARRAY_SIZE(hwmon_chip_attr_templates),
+	[hwmon_temp] = ARRAY_SIZE(hwmon_temp_attr_templates),
+};
+
+static int hwmon_num_channel_attrs(const struct hwmon_channel_info *info)
+{
+	int i, n;
+
+	for (i = n = 0; info->config[i]; i++)
+		n += hweight32(info->config[i]);
+
+	return n;
+}
+
+static int hwmon_genattrs(struct device *dev,
+			  const void *drvdata,
+			  struct attribute **attrs,
+			  const struct hwmon_ops *ops,
+			  const struct hwmon_channel_info *info)
+{
+	const char * const *templates;
+	int template_size;
+	int i, aindex = 0;
+
+	if (info->type >= ARRAY_SIZE(__templates))
+		return -EINVAL;
+
+	templates = __templates[info->type];
+	template_size = __templates_size[info->type];
+
+	for (i = 0; info->config[i]; i++) {
+		u32 attr_mask = info->config[i];
+		u32 attr;
+
+		while (attr_mask) {
+			struct attribute *a;
+
+			attr = __ffs(attr_mask);
+			attr_mask &= ~BIT(attr);
+			if (attr >= template_size)
+				return -EINVAL;
+			a = hwmon_genattr(dev, drvdata, info->type, attr, i,
+					  templates[attr], ops);
+			if (IS_ERR(a)) {
+				if (PTR_ERR(a) != -ENOENT)
+					return PTR_ERR(a);
+				continue;
+			}
+			attrs[aindex++] = a;
+		}
+	}
+	return aindex;
+}
+
+static struct attribute **
+__hwmon_create_attrs(struct device *dev, const void *drvdata,
+		     const struct hwmon_chip_info *chip)
+{
+	int ret, i, aindex = 0, nattrs = 0;
+	struct attribute **attrs;
+
+	for (i = 0; chip->info[i]; i++)
+		nattrs += hwmon_num_channel_attrs(chip->info[i]);
+
+	if (nattrs == 0)
+		return ERR_PTR(-EINVAL);
+
+	attrs = devm_kcalloc(dev, nattrs + 1, sizeof(*attrs), GFP_KERNEL);
+	if (attrs == NULL)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; chip->info[i]; i++) {
+		ret = hwmon_genattrs(dev, drvdata, &attrs[aindex], chip->ops,
+				     chip->info[i]);
+		if (ret < 0)
+			return ERR_PTR(ret);
+		aindex += ret;
+	}
+
+	return attrs;
+}
+
+static struct device *
+__hwmon_device_register(struct device *dev, const char *name, void *drvdata,
+			const struct hwmon_chip_info *chip,
+			const struct attribute_group **groups)
 {
 	struct hwmon_device *hwdev;
-	int err, id;
+	struct device *hdev;
+	int i, j, err, id;
 
 	/* Do not accept invalid characters in hwmon name attribute */
 	if (name && (!strlen(name) || strpbrk(name, "-* \t\n")))
@@ -114,28 +392,128 @@ hwmon_device_register_with_groups(struct device *dev, const char *name,
 		goto ida_remove;
 	}
 
+	hdev = &hwdev->dev;
+
+	if (chip && chip->ops->is_visible) {
+		struct attribute **attrs;
+		int ngroups = 2;
+
+		if (groups)
+			for (i = 0; groups[i]; i++)
+				ngroups++;
+
+		hwdev->groups = devm_kcalloc(dev, ngroups, sizeof(*groups),
+					     GFP_KERNEL);
+		if (hwdev->groups == NULL)
+			return ERR_PTR(-ENOMEM);
+
+		attrs = __hwmon_create_attrs(dev, drvdata, chip);
+		if (IS_ERR(attrs)) {
+			err = PTR_ERR(attrs);
+			goto free_hwmon;
+		}
+
+		hwdev->group.attrs = attrs;
+		ngroups = 0;
+		hwdev->groups[ngroups++] = &hwdev->group;
+
+		if (groups) {
+			for (i = 0; groups[i]; i++)
+				hwdev->groups[ngroups++] = groups[i];
+		}
+
+		hdev->groups = hwdev->groups;
+	} else {
+		hdev->groups = groups;
+	}
+
 	hwdev->name = name;
-	hwdev->dev.class = &hwmon_class;
-	hwdev->dev.parent = dev;
-	hwdev->dev.groups = groups;
-	hwdev->dev.of_node = dev ? dev->of_node : NULL;
-	dev_set_drvdata(&hwdev->dev, drvdata);
-	dev_set_name(&hwdev->dev, HWMON_ID_FORMAT, id);
-	err = device_register(&hwdev->dev);
+	hdev->class = &hwmon_class;
+	hdev->parent = dev;
+	hdev->of_node = dev ? dev->of_node : NULL;
+	hwdev->chip = chip;
+	dev_set_drvdata(hdev, drvdata);
+	dev_set_name(hdev, HWMON_ID_FORMAT, id);
+	err = device_register(hdev);
 	if (err)
-		goto free;
+		goto free_hwmon;
+
+	if (chip && chip->ops->is_visible && chip->ops->read &&
+	    chip->info[0]->type == hwmon_chip &&
+	    (chip->info[0]->config[0] & HWMON_C_REGISTER_TZ)) {
+		const struct hwmon_channel_info **info = chip->info;
+
+		for (i = 1; info[i]; i++) {
+			if (info[i]->type != hwmon_temp)
+				continue;
+
+			for (j = 0; info[i]->config[j]; j++) {
+				if (!chip->ops->is_visible(drvdata, hwmon_temp,
+							   hwmon_temp_input, j))
+					continue;
+				if (info[i]->config[j] & HWMON_T_INPUT)
+					hwmon_thermal_add_sensor(dev, hwdev, j);
+			}
+		}
+	}
 
-	return &hwdev->dev;
+	return hdev;
 
-free:
+free_hwmon:
 	kfree(hwdev);
 ida_remove:
 	ida_simple_remove(&hwmon_ida, id);
 	return ERR_PTR(err);
 }
+
+/**
+ * hwmon_device_register_with_groups - register w/ hwmon
+ * @dev: the parent device
+ * @name: hwmon name attribute
+ * @drvdata: driver data to attach to created device
+ * @groups: List of attribute groups to create
+ *
+ * hwmon_device_unregister() must be called when the device is no
+ * longer needed.
+ *
+ * Returns the pointer to the new device.
+ */
+struct device *
+hwmon_device_register_with_groups(struct device *dev, const char *name,
+				  void *drvdata,
+				  const struct attribute_group **groups)
+{
+	return __hwmon_device_register(dev, name, drvdata, NULL, groups);
+}
 EXPORT_SYMBOL_GPL(hwmon_device_register_with_groups);
 
 /**
+ * hwmon_device_register_with_info - register w/ hwmon
+ * @dev: the parent device
+ * @name: hwmon name attribute
+ * @drvdata: driver data to attach to created device
+ * @info: Pointer to hwmon chip information
+ * @groups - pointer to list of driver specific attribute groups
+ *
+ * hwmon_device_unregister() must be called when the device is no
+ * longer needed.
+ *
+ * Returns the pointer to the new device.
+ */
+struct device *
+hwmon_device_register_with_info(struct device *dev, const char *name,
+				  void *drvdata,
+				  const struct hwmon_chip_info *chip,
+				  const struct attribute_group **groups)
+{
+	if (chip && (!chip->ops || !chip->info))
+		return ERR_PTR(-EINVAL);
+
+	return __hwmon_device_register(dev, name, drvdata, chip, groups);
+}
+EXPORT_SYMBOL_GPL(hwmon_device_register_with_info);
+
+/**
  * hwmon_device_register - register w/ hwmon
  * @dev: the device to register
  *
@@ -213,6 +591,47 @@ error:
 }
 EXPORT_SYMBOL_GPL(devm_hwmon_device_register_with_groups);
 
+/**
+ * devm_hwmon_device_register_with_info - register w/ hwmon
+ * @dev: the parent device
+ * @name: hwmon name attribute
+ * @drvdata: driver data to attach to created device
+ * @info: Pointer to hwmon chip information
+ * @groups - pointer to list of driver specific attribute groups
+ *
+ * Returns the pointer to the new device. The new device is automatically
+ * unregistered with the parent device.
+ */
+struct device *
+devm_hwmon_device_register_with_info(struct device *dev, const char *name,
+				     void *drvdata,
+				     const struct hwmon_chip_info *chip,
+				     const struct attribute_group **groups)
+{
+	struct device **ptr, *hwdev;
+
+	if (!dev)
+		return ERR_PTR(-EINVAL);
+
+	ptr = devres_alloc(devm_hwmon_release, sizeof(*ptr), GFP_KERNEL);
+	if (!ptr)
+		return ERR_PTR(-ENOMEM);
+
+	hwdev = hwmon_device_register_with_info(dev, name, drvdata, chip,
+						groups);
+	if (IS_ERR(hwdev))
+		goto error;
+
+	*ptr = hwdev;
+	devres_add(dev, ptr);
+	return hwdev;
+
+error:
+	devres_free(ptr);
+	return hwdev;
+}
+EXPORT_SYMBOL_GPL(devm_hwmon_device_register_with_info);
+
 static int devm_hwmon_match(struct device *dev, void *res, void *data)
 {
 	struct device **hwdev = res;
diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
index 09354f6c1d63..99250ad092fd 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -14,9 +14,121 @@
 #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.
+ *		Optional.
+ * @read:       Read callback. Optional.
+ * @write:	Write callback. Optional.
+ */
+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);
+};
+
+/**
+ * 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 +138,16 @@ 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);
-- 
2.5.0

[PATCH 2/7] hwmon: (core) Add voltage attribute support to new API

[Guenter Roeck]

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/hwmon.c | 21 +++++++++++++++++++++
 include/linux/hwmon.h | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index 9530644ae297..d2916074befd 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -250,6 +250,7 @@ static struct attribute *hwmon_genattr(struct device *dev,
 
 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_update_interval] = "update_interval",
 	[hwmon_chip_alarms] = "alarms",
 };
@@ -281,14 +282,34 @@ static const char * const hwmon_temp_attr_templates[] = {
 	[hwmon_temp_reset_history] = "temp%d_reset_history",
 };
 
+static const char * const hwmon_in_attr_templates[] = {
+	[hwmon_in_input] = "in%d_input",
+	[hwmon_in_min] = "in%d_min",
+	[hwmon_in_max] = "in%d_max",
+	[hwmon_in_lcrit] = "in%d_lcrit",
+	[hwmon_in_crit] = "in%d_crit",
+	[hwmon_in_average] = "in%d_average",
+	[hwmon_in_lowest] = "in%d_lowest",
+	[hwmon_in_highest] = "in%d_highest",
+	[hwmon_in_reset_history] = "in%d_reset_history",
+	[hwmon_in_label] = "in%d_label",
+	[hwmon_in_alarm] = "in%d_alarm",
+	[hwmon_in_min_alarm] = "in%d_min_alarm",
+	[hwmon_in_max_alarm] = "in%d_max_alarm",
+	[hwmon_in_lcrit_alarm] = "in%d_lcrit_alarm",
+	[hwmon_in_crit_alarm] = "in%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,
 };
 
 static const int __templates_size[] = {
 	[hwmon_chip] = ARRAY_SIZE(hwmon_chip_attr_templates),
 	[hwmon_temp] = ARRAY_SIZE(hwmon_temp_attr_templates),
+	[hwmon_in] = ARRAY_SIZE(hwmon_in_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 99250ad092fd..5e632c0fcbf4 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -30,6 +30,7 @@ enum hwmon_sensor_types {
 
 enum hwmon_chip_attributes {
 	hwmon_chip_temp_reset_history,
+	hwmon_chip_in_reset_history,
 	hwmon_chip_register_tz,
 	hwmon_chip_update_interval,
 	hwmon_chip_alarms,
@@ -91,6 +92,40 @@ enum hwmon_temp_attributes {
 #define HWMON_T_HIGHEST		BIT(hwmon_temp_highest)
 #define HWMON_T_RESET_HISTORY	BIT(hwmon_temp_reset_history)
 
+enum hwmon_in_attributes {
+	hwmon_in_input,
+	hwmon_in_min,
+	hwmon_in_max,
+	hwmon_in_lcrit,
+	hwmon_in_crit,
+	hwmon_in_average,
+	hwmon_in_lowest,
+	hwmon_in_highest,
+	hwmon_in_reset_history,
+	hwmon_in_label,
+	hwmon_in_alarm,
+	hwmon_in_min_alarm,
+	hwmon_in_max_alarm,
+	hwmon_in_lcrit_alarm,
+	hwmon_in_crit_alarm,
+};
+
+#define HWMON_I_INPUT		BIT(hwmon_in_input)
+#define HWMON_I_MIN		BIT(hwmon_in_min)
+#define HWMON_I_MAX		BIT(hwmon_in_max)
+#define HWMON_I_LCRIT		BIT(hwmon_in_lcrit)
+#define HWMON_I_CRIT		BIT(hwmon_in_crit)
+#define HWMON_I_AVERAGE		BIT(hwmon_in_average)
+#define HWMON_I_LOWEST		BIT(hwmon_in_lowest)
+#define HWMON_I_HIGHEST		BIT(hwmon_in_highest)
+#define HWMON_I_RESET_HISTORY	BIT(hwmon_in_reset_history)
+#define HWMON_I_LABEL		BIT(hwmon_in_label)
+#define HWMON_I_ALARM		BIT(hwmon_in_alarm)
+#define HWMON_I_MIN_ALARM	BIT(hwmon_in_min_alarm)
+#define HWMON_I_MAX_ALARM	BIT(hwmon_in_max_alarm)
+#define HWMON_I_LCRIT_ALARM	BIT(hwmon_in_lcrit_alarm)
+#define HWMON_I_CRIT_ALARM	BIT(hwmon_in_crit_alarm)
+
 /**
  * struct hwmon_ops - hwmon device operations
  * @is_visible: Callback to return attribute visibility.
-- 
2.5.0

[PATCH 2/7] hwmon: (core) Add voltage attribute support to new API

[Guenter Roeck]

Signed-off-by: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
---
 drivers/hwmon/hwmon.c | 21 +++++++++++++++++++++
 include/linux/hwmon.h | 35 +++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index 9530644ae297..d2916074befd 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -250,6 +250,7 @@ static struct attribute *hwmon_genattr(struct device *dev,
 
 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_update_interval] = "update_interval",
 	[hwmon_chip_alarms] = "alarms",
 };
@@ -281,14 +282,34 @@ static const char * const hwmon_temp_attr_templates[] = {
 	[hwmon_temp_reset_history] = "temp%d_reset_history",
 };
 
+static const char * const hwmon_in_attr_templates[] = {
+	[hwmon_in_input] = "in%d_input",
+	[hwmon_in_min] = "in%d_min",
+	[hwmon_in_max] = "in%d_max",
+	[hwmon_in_lcrit] = "in%d_lcrit",
+	[hwmon_in_crit] = "in%d_crit",
+	[hwmon_in_average] = "in%d_average",
+	[hwmon_in_lowest] = "in%d_lowest",
+	[hwmon_in_highest] = "in%d_highest",
+	[hwmon_in_reset_history] = "in%d_reset_history",
+	[hwmon_in_label] = "in%d_label",
+	[hwmon_in_alarm] = "in%d_alarm",
+	[hwmon_in_min_alarm] = "in%d_min_alarm",
+	[hwmon_in_max_alarm] = "in%d_max_alarm",
+	[hwmon_in_lcrit_alarm] = "in%d_lcrit_alarm",
+	[hwmon_in_crit_alarm] = "in%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,
 };
 
 static const int __templates_size[] = {
 	[hwmon_chip] = ARRAY_SIZE(hwmon_chip_attr_templates),
 	[hwmon_temp] = ARRAY_SIZE(hwmon_temp_attr_templates),
+	[hwmon_in] = ARRAY_SIZE(hwmon_in_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 99250ad092fd..5e632c0fcbf4 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -30,6 +30,7 @@ enum hwmon_sensor_types {
 
 enum hwmon_chip_attributes {
 	hwmon_chip_temp_reset_history,
+	hwmon_chip_in_reset_history,
 	hwmon_chip_register_tz,
 	hwmon_chip_update_interval,
 	hwmon_chip_alarms,
@@ -91,6 +92,40 @@ enum hwmon_temp_attributes {
 #define HWMON_T_HIGHEST		BIT(hwmon_temp_highest)
 #define HWMON_T_RESET_HISTORY	BIT(hwmon_temp_reset_history)
 
+enum hwmon_in_attributes {
+	hwmon_in_input,
+	hwmon_in_min,
+	hwmon_in_max,
+	hwmon_in_lcrit,
+	hwmon_in_crit,
+	hwmon_in_average,
+	hwmon_in_lowest,
+	hwmon_in_highest,
+	hwmon_in_reset_history,
+	hwmon_in_label,
+	hwmon_in_alarm,
+	hwmon_in_min_alarm,
+	hwmon_in_max_alarm,
+	hwmon_in_lcrit_alarm,
+	hwmon_in_crit_alarm,
+};
+
+#define HWMON_I_INPUT		BIT(hwmon_in_input)
+#define HWMON_I_MIN		BIT(hwmon_in_min)
+#define HWMON_I_MAX		BIT(hwmon_in_max)
+#define HWMON_I_LCRIT		BIT(hwmon_in_lcrit)
+#define HWMON_I_CRIT		BIT(hwmon_in_crit)
+#define HWMON_I_AVERAGE		BIT(hwmon_in_average)
+#define HWMON_I_LOWEST		BIT(hwmon_in_lowest)
+#define HWMON_I_HIGHEST		BIT(hwmon_in_highest)
+#define HWMON_I_RESET_HISTORY	BIT(hwmon_in_reset_history)
+#define HWMON_I_LABEL		BIT(hwmon_in_label)
+#define HWMON_I_ALARM		BIT(hwmon_in_alarm)
+#define HWMON_I_MIN_ALARM	BIT(hwmon_in_min_alarm)
+#define HWMON_I_MAX_ALARM	BIT(hwmon_in_max_alarm)
+#define HWMON_I_LCRIT_ALARM	BIT(hwmon_in_lcrit_alarm)
+#define HWMON_I_CRIT_ALARM	BIT(hwmon_in_crit_alarm)
+
 /**
  * struct hwmon_ops - hwmon device operations
  * @is_visible: Callback to return attribute visibility.
-- 
2.5.0

[PATCH 3/7] hwmon: (core) Add current attribute support to new API

[Guenter Roeck]

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/hwmon.c | 21 +++++++++++++++++++++
 include/linux/hwmon.h | 36 ++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index d2916074befd..8c3c7ffe828b 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -251,6 +251,7 @@ static struct attribute *hwmon_genattr(struct device *dev,
 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_update_interval] = "update_interval",
 	[hwmon_chip_alarms] = "alarms",
 };
@@ -300,16 +301,36 @@ static const char * const hwmon_in_attr_templates[] = {
 	[hwmon_in_crit_alarm] = "in%d_crit_alarm",
 };
 
+static const char * const hwmon_curr_attr_templates[] = {
+	[hwmon_curr_input] = "curr%d_input",
+	[hwmon_curr_min] = "curr%d_min",
+	[hwmon_curr_max] = "curr%d_max",
+	[hwmon_curr_lcrit] = "curr%d_lcrit",
+	[hwmon_curr_crit] = "curr%d_crit",
+	[hwmon_curr_average] = "curr%d_average",
+	[hwmon_curr_lowest] = "curr%d_lowest",
+	[hwmon_curr_highest] = "curr%d_highest",
+	[hwmon_curr_reset_history] = "curr%d_reset_history",
+	[hwmon_curr_label] = "curr%d_label",
+	[hwmon_curr_alarm] = "curr%d_alarm",
+	[hwmon_curr_min_alarm] = "curr%d_min_alarm",
+	[hwmon_curr_max_alarm] = "curr%d_max_alarm",
+	[hwmon_curr_lcrit_alarm] = "curr%d_lcrit_alarm",
+	[hwmon_curr_crit_alarm] = "curr%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,
 };
 
 static const int __templates_size[] = {
 	[hwmon_chip] = ARRAY_SIZE(hwmon_chip_attr_templates),
 	[hwmon_temp] = ARRAY_SIZE(hwmon_temp_attr_templates),
 	[hwmon_in] = ARRAY_SIZE(hwmon_in_attr_templates),
+	[hwmon_curr] = ARRAY_SIZE(hwmon_curr_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 5e632c0fcbf4..bac3c5dc672f 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -31,6 +31,7 @@ enum hwmon_sensor_types {
 enum hwmon_chip_attributes {
 	hwmon_chip_temp_reset_history,
 	hwmon_chip_in_reset_history,
+	hwmon_chip_curr_reset_history,
 	hwmon_chip_register_tz,
 	hwmon_chip_update_interval,
 	hwmon_chip_alarms,
@@ -38,6 +39,7 @@ 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_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)
@@ -126,6 +128,40 @@ enum hwmon_in_attributes {
 #define HWMON_I_LCRIT_ALARM	BIT(hwmon_in_lcrit_alarm)
 #define HWMON_I_CRIT_ALARM	BIT(hwmon_in_crit_alarm)
 
+enum hwmon_curr_attributes {
+	hwmon_curr_input,
+	hwmon_curr_min,
+	hwmon_curr_max,
+	hwmon_curr_lcrit,
+	hwmon_curr_crit,
+	hwmon_curr_average,
+	hwmon_curr_lowest,
+	hwmon_curr_highest,
+	hwmon_curr_reset_history,
+	hwmon_curr_label,
+	hwmon_curr_alarm,
+	hwmon_curr_min_alarm,
+	hwmon_curr_max_alarm,
+	hwmon_curr_lcrit_alarm,
+	hwmon_curr_crit_alarm,
+};
+
+#define HWMON_C_INPUT		BIT(hwmon_curr_input)
+#define HWMON_C_MIN		BIT(hwmon_curr_min)
+#define HWMON_C_MAX		BIT(hwmon_curr_max)
+#define HWMON_C_LCRIT		BIT(hwmon_curr_lcrit)
+#define HWMON_C_CRIT		BIT(hwmon_curr_crit)
+#define HWMON_C_AVERAGE		BIT(hwmon_curr_average)
+#define HWMON_C_LOWEST		BIT(hwmon_curr_lowest)
+#define HWMON_C_HIGHEST		BIT(hwmon_curr_highest)
+#define HWMON_C_RESET_HISTORY	BIT(hwmon_curr_reset_history)
+#define HWMON_C_LABEL		BIT(hwmon_curr_label)
+#define HWMON_C_ALARM		BIT(hwmon_curr_alarm)
+#define HWMON_C_MIN_ALARM	BIT(hwmon_curr_min_alarm)
+#define HWMON_C_MAX_ALARM	BIT(hwmon_curr_max_alarm)
+#define HWMON_C_LCRIT_ALARM	BIT(hwmon_curr_lcrit_alarm)
+#define HWMON_C_CRIT_ALARM	BIT(hwmon_curr_crit_alarm)
+
 /**
  * struct hwmon_ops - hwmon device operations
  * @is_visible: Callback to return attribute visibility.
-- 
2.5.0

[PATCH 4/7] hwmon: (core) Add power attribute support to new API

[Guenter Roeck]

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 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 8c3c7ffe828b..dff07e8f9509 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -252,6 +252,7 @@ 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",
 };
@@ -319,11 +320,39 @@ 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[] = {
@@ -331,6 +360,7 @@ 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 bac3c5dc672f..4de6e2af29ea 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.
-- 
2.5.0

[PATCH 5/7] hwmon: (core) Add energy and humidity attribute support to new API

[Guenter Roeck]

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/hwmon.c | 20 ++++++++++++++++++++
 include/linux/hwmon.h | 29 +++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index dff07e8f9509..363ec5660d0c 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -347,12 +347,30 @@ static const char * const hwmon_power_attr_templates[] = {
 	[hwmon_power_crit_alarm] = "power%d_crit_alarm",
 };
 
+static const char * const hwmon_energy_attr_templates[] = {
+	[hwmon_energy_input] = "energy%d_input",
+	[hwmon_energy_label] = "energy%d_label",
+};
+
+static const char * const hwmon_humidity_attr_templates[] = {
+	[hwmon_humidity_input] = "humidity%d_input",
+	[hwmon_humidity_label] = "humidity%d_label",
+	[hwmon_humidity_min] = "humidity%d_min",
+	[hwmon_humidity_min_hyst] = "humidity%d_min_hyst",
+	[hwmon_humidity_max] = "humidity%d_max",
+	[hwmon_humidity_max_hyst] = "humidity%d_max_hyst",
+	[hwmon_humidity_alarm] = "humidity%d_alarm",
+	[hwmon_humidity_fault] = "humidity%d_fault",
+};
+
 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,
+	[hwmon_energy] = hwmon_energy_attr_templates,
+	[hwmon_humidity] = hwmon_humidity_attr_templates,
 };
 
 static const int __templates_size[] = {
@@ -361,6 +379,8 @@ static const int __templates_size[] = {
 	[hwmon_in] = ARRAY_SIZE(hwmon_in_attr_templates),
 	[hwmon_curr] = ARRAY_SIZE(hwmon_curr_attr_templates),
 	[hwmon_power] = ARRAY_SIZE(hwmon_power_attr_templates),
+	[hwmon_energy] = ARRAY_SIZE(hwmon_energy_attr_templates),
+	[hwmon_humidity] = ARRAY_SIZE(hwmon_humidity_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 4de6e2af29ea..a0b82027ae07 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -26,6 +26,7 @@ enum hwmon_sensor_types {
 	hwmon_curr,
 	hwmon_power,
 	hwmon_energy,
+	hwmon_humidity,
 };
 
 enum hwmon_chip_attributes {
@@ -216,6 +217,34 @@ enum hwmon_power_attributes {
 #define HWMON_P_MAX_ALARM		BIT(hwmon_power_max_alarm)
 #define HWMON_P_CRIT_ALARM		BIT(hwmon_power_crit_alarm)
 
+enum hwmon_energy_attributes {
+	hwmon_energy_input,
+	hwmon_energy_label,
+};
+
+#define HWMON_E_INPUT			BIT(hwmon_energy_input)
+#define HWMON_E_LABEL			BIT(hwmon_energy_label)
+
+enum hwmon_humidity_attributes {
+	hwmon_humidity_input,
+	hwmon_humidity_label,
+	hwmon_humidity_min,
+	hwmon_humidity_min_hyst,
+	hwmon_humidity_max,
+	hwmon_humidity_max_hyst,
+	hwmon_humidity_alarm,
+	hwmon_humidity_fault,
+};
+
+#define HWMON_H_INPUT			BIT(hwmon_humidity_input)
+#define HWMON_H_LABEL			BIT(hwmon_humidity_label)
+#define HWMON_H_MIN			BIT(hwmon_humidity_min)
+#define HWMON_H_MIN_HYST		BIT(hwmon_humidity_min_hyst)
+#define HWMON_H_MAX			BIT(hwmon_humidity_max)
+#define HWMON_H_MAX_HYST		BIT(hwmon_humidity_max_hyst)
+#define HWMON_H_ALARM			BIT(hwmon_humidity_alarm)
+#define HWMON_H_FAULT			BIT(hwmon_humidity_fault)
+
 /**
  * struct hwmon_ops - hwmon device operations
  * @is_visible: Callback to return attribute visibility.
-- 
2.5.0

[PATCH 6/7] hwmon: (core) Add fan attribute support to new API

[Guenter Roeck]

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 drivers/hwmon/hwmon.c | 16 ++++++++++++++++
 include/linux/hwmon.h | 27 +++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index 363ec5660d0c..ca18a6f4f9bc 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -363,6 +363,20 @@ static const char * const hwmon_humidity_attr_templates[] = {
 	[hwmon_humidity_fault] = "humidity%d_fault",
 };
 
+static const char * const hwmon_fan_attr_templates[] = {
+	[hwmon_fan_input] = "fan%d_input",
+	[hwmon_fan_label] = "fan%d_label",
+	[hwmon_fan_min] = "fan%d_min",
+	[hwmon_fan_max] = "fan%d_max",
+	[hwmon_fan_div] = "fan%d_div",
+	[hwmon_fan_pulses] = "fan%d_pulses",
+	[hwmon_fan_target] = "fan%d_target",
+	[hwmon_fan_alarm] = "fan%d_alarm",
+	[hwmon_fan_min_alarm] = "fan%d_min_alarm",
+	[hwmon_fan_max_alarm] = "fan%d_max_alarm",
+	[hwmon_fan_fault] = "fan%d_fault",
+};
+
 static const char * const *__templates[] = {
 	[hwmon_chip] = hwmon_chip_attr_templates,
 	[hwmon_temp] = hwmon_temp_attr_templates,
@@ -371,6 +385,7 @@ static const char * const *__templates[] = {
 	[hwmon_power] = hwmon_power_attr_templates,
 	[hwmon_energy] = hwmon_energy_attr_templates,
 	[hwmon_humidity] = hwmon_humidity_attr_templates,
+	[hwmon_fan] = hwmon_fan_attr_templates,
 };
 
 static const int __templates_size[] = {
@@ -381,6 +396,7 @@ static const int __templates_size[] = {
 	[hwmon_power] = ARRAY_SIZE(hwmon_power_attr_templates),
 	[hwmon_energy] = ARRAY_SIZE(hwmon_energy_attr_templates),
 	[hwmon_humidity] = ARRAY_SIZE(hwmon_humidity_attr_templates),
+	[hwmon_fan] = ARRAY_SIZE(hwmon_fan_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 a0b82027ae07..b2fdaaa7b7ba 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -27,6 +27,7 @@ enum hwmon_sensor_types {
 	hwmon_power,
 	hwmon_energy,
 	hwmon_humidity,
+	hwmon_fan,
 };
 
 enum hwmon_chip_attributes {
@@ -245,6 +246,32 @@ enum hwmon_humidity_attributes {
 #define HWMON_H_ALARM			BIT(hwmon_humidity_alarm)
 #define HWMON_H_FAULT			BIT(hwmon_humidity_fault)
 
+enum hwmon_fan_attributes {
+	hwmon_fan_input,
+	hwmon_fan_label,
+	hwmon_fan_min,
+	hwmon_fan_max,
+	hwmon_fan_div,
+	hwmon_fan_pulses,
+	hwmon_fan_target,
+	hwmon_fan_alarm,
+	hwmon_fan_min_alarm,
+	hwmon_fan_max_alarm,
+	hwmon_fan_fault,
+};
+
+#define HWMON_F_INPUT			BIT(hwmon_fan_input)
+#define HWMON_F_LABEL			BIT(hwmon_fan_label)
+#define HWMON_F_MIN			BIT(hwmon_fan_min)
+#define HWMON_F_MAX			BIT(hwmon_fan_max)
+#define HWMON_F_DIV			BIT(hwmon_fan_div)
+#define HWMON_F_PULSES			BIT(hwmon_fan_pulses)
+#define HWMON_F_TARGET			BIT(hwmon_fan_target)
+#define HWMON_F_ALARM			BIT(hwmon_fan_alarm)
+#define HWMON_F_MIN_ALARM		BIT(hwmon_fan_min_alarm)
+#define HWMON_F_MAX_ALARM		BIT(hwmon_fan_max_alarm)
+#define HWMON_F_FAULT			BIT(hwmon_fan_fault)
+
 /**
  * struct hwmon_ops - hwmon device operations
  * @is_visible: Callback to return attribute visibility.
-- 
2.5.0

[PATCH 7/7] hwmon: (core) Document new kernel API

[Guenter Roeck]

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

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---
 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..1a96c36532f2 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 priovided 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 atributes. 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

Re: [PATCH 0/5] hwmon: New hwmon registration API

[Punit Agrawal]

Hi Guenter,

Guenter Roeck <linux@roeck-us.net> writes:

> 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 introduces the API as well as support
> for temperature sensors. Subsequent patches introduce support for
> voltage, current, power, energy, humidity, and fan speed sensors.
>
> The series was tested by converting several drivers (lm75, lm90, tmp102,
> tmp421, ltc4245) to the new API. Testing was done with with real chips
> as well as with the hwmon driver module test code available at
> https://github.com/groeck/module-tests.

I like this series - it takes all of the attributes' handling out of the
individual driver code and moving it to hwmon core.

Having attempted a port of scpi-hwmon.c, I think that driver will not
gain a big savings in line count. Though it'll help separate access to
sensors from sysfs related code - which I think is worth the change.

FWIW,

        Acked-by: Punit Agrawal <punit.agrawal@arm.com>

Thanks,
Punit

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Re: [PATCH 0/5] hwmon: New hwmon registration API

[Guenter Roeck]

Hi Punit,

On 07/08/2016 02:31 AM, Punit Agrawal wrote:
> Hi Guenter,
>
> Guenter Roeck <linux@roeck-us.net> writes:
>
>> 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 introduces the API as well as support
>> for temperature sensors. Subsequent patches introduce support for
>> voltage, current, power, energy, humidity, and fan speed sensors.
>>
>> The series was tested by converting several drivers (lm75, lm90, tmp102,
>> tmp421, ltc4245) to the new API. Testing was done with with real chips
>> as well as with the hwmon driver module test code available at
>> https://github.com/groeck/module-tests.
>
> I like this series - it takes all of the attributes' handling out of the
> individual driver code and moving it to hwmon core.
>
> Having attempted a port of scpi-hwmon.c, I think that driver will not
> gain a big savings in line count. Though it'll help separate access to
> sensors from sysfs related code - which I think is worth the change.
>

 From what I have seen, savings are for the most part on the binary image size.
I have not seen much if any savings in terms of LOC, though that may in part
be because of my coding style.

Here is the result from the conversions I have done so far.

Old:

    text	   data	    bss	    dec	    hex	filename
    5730	   4056	     64	   9850	   267a	drivers/hwmon/lm95245.o
    5941	   4240	     64	  10245	   2805	drivers/hwmon/lm95241.o
    5361	   3584	     64	   9009	   2331	drivers/hwmon/jc42.o
    8609	  10872	     64	  19545	   4c59	drivers/hwmon/max31790.o
    9080	  13232	     64	  22376	   5768	drivers/hwmon/nct7904.o
    6574	   8498	     64	  15136	   3b20	drivers/hwmon/ltc4245.o
    4516	   3464	     64	   8044	   1f6c	drivers/hwmon/tmp421.o
    4223	   2744	     64	   7031	   1b77	drivers/hwmon/tmp102.o
   21757	  13496	     64	  35317	   89f5	drivers/hwmon/lm90.o
    6804	   3240	     64	  10108	   277c	drivers/hwmon/lm75.o

New:

    text	   data	    bss	    dec	    hex	filename
    5166	   1568	    128	   6862	   1ace	drivers/hwmon/lm95245.o
    4334	   1664	     64	   6062	   17ae	drivers/hwmon/lm95241.o
    4579	   1456	     64	   6099	   17d3	drivers/hwmon/jc42.o
    3687	   1312	     64	   5063	   13c7	drivers/hwmon/max31790.o
    3905	   1720	     64	   5689	   1639	drivers/hwmon/nct7904.o
    3989	   1658	     64	   5711	   164f	drivers/hwmon/ltc4245.o
    3557	   1408	     64	   5029	   13a5	drivers/hwmon/tmp421.o
    4037	   2200	     64	   6301	   189d	drivers/hwmon/tmp102.o
   16485	   4288	     64	  20837	   5165	drivers/hwmon/lm90.o
    5762	   2128	     64	   7954	   1f12	drivers/hwmon/lm75.o

This is with x86_64.

The largest savings are in drivers with simple access methods and
a large number of attributes. The scpi driver is somewhat of an
exception since it creates its attribute data structures dynamically;
I would not expect to see much savings in that driver.

> FWIW,
>
>          Acked-by: Punit Agrawal <punit.agrawal@arm.com>
>

Thanks!

Guenter

Re: [PATCH 1/7] hwmon: (core) New hwmon registration API

[Jonathan Cameron]

On 26/06/16 04:26, Guenter Roeck wrote:
> 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 size is typically reduced by 20-50% 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.
> 
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Hi Guenter.

Sorry it took me so long to get to this....

Anyhow, mostly looks clean, effective and consise to me.
Various bits and pieces inline.  There are a few bits I might (when time
allows) lift over to iio as they are nicer than what we have.

My one lesson learned from IIO is always be wary of space in bitmaps.  We
haven't run out yet but are getting close.  You may end up in a similar
state here a few years down the line.

Jonathan
> ---
>  drivers/hwmon/hwmon.c | 485 ++++++++++++++++++++++++++++++++++++++++++++++----
>  include/linux/hwmon.h | 122 +++++++++++++
>  2 files changed, 574 insertions(+), 33 deletions(-)
> 
> diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
> index a26c385a435b..9530644ae297 100644
> --- a/drivers/hwmon/hwmon.c
> +++ b/drivers/hwmon/hwmon.c
> @@ -12,17 +12,16 @@
>  
>  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>  
> -#include <linux/module.h>
> +#include <linux/bitops.h>
>  #include <linux/device.h>
>  #include <linux/err.h>
> -#include <linux/slab.h>
> -#include <linux/kdev_t.h>
> -#include <linux/idr.h>
>  #include <linux/hwmon.h>
> -#include <linux/gfp.h>
> -#include <linux/spinlock.h>
> +#include <linux/idr.h>
> +#include <linux/module.h>
Some unconnected changes in this.  Arguably reordering is good and
all but should be in a precursor patch so it's obvious what has
been added or removed here.

>  #include <linux/pci.h>
> +#include <linux/slab.h>
>  #include <linux/string.h>
> +#include <linux/thermal.h>
>  
>  #define HWMON_ID_PREFIX "hwmon"
>  #define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
> @@ -30,9 +29,33 @@
>  struct hwmon_device {
>  	const char *name;
>  	struct device dev;
> +	const struct hwmon_chip_info *chip;
> +
> +	struct attribute_group group;
> +	const struct attribute_group **groups;
>  };
>  #define to_hwmon_device(d) container_of(d, struct hwmon_device, dev)
>  
> +struct hwmon_device_attribute {
> +	struct device_attribute dev_attr;
> +	const struct hwmon_ops *ops;
> +	enum hwmon_sensor_types type;
> +	u32 attr;
> +	int index;
> +};
> +#define to_hwmon_attr(d) \
> +	container_of(d, struct hwmon_device_attribute, dev_attr)
> +
> +/*
> + * Thermal zone information
> + * In addition to the reference to the hwmon device,
> + * also provides the sensor index.
> + */
> +struct hwmon_thermal_data {
> +	struct hwmon_device *hwdev;	/* Reference to hwmon device */
> +	int index;			/* sensor index */
> +};
> +
>  static ssize_t
>  show_name(struct device *dev, struct device_attribute *attr, char *buf)
>  {
> @@ -80,25 +103,280 @@ static struct class hwmon_class = {
>  
>  static DEFINE_IDA(hwmon_ida);
>  
> -/**
> - * hwmon_device_register_with_groups - register w/ hwmon
> - * @dev: the parent device
> - * @name: hwmon name attribute
> - * @drvdata: driver data to attach to created device
> - * @groups: List of attribute groups to create
> - *
> - * hwmon_device_unregister() must be called when the device is no
> - * longer needed.
> - *
> - * Returns the pointer to the new device.
> - */
> -struct device *
> -hwmon_device_register_with_groups(struct device *dev, const char *name,
> -				  void *drvdata,
> -				  const struct attribute_group **groups)
> +/* Thermal zone handling */
> +
> +static int hwmon_thermal_get_temp(void *data, int *temp)
> +{
> +	struct hwmon_thermal_data *tdata = data;
> +	struct hwmon_device *hwdev = tdata->hwdev;
> +	int ret;
> +	long t;
> +
> +	ret = hwdev->chip->ops->read(&hwdev->dev, hwmon_temp, hwmon_temp_input,
> +				     tdata->index, &t);
> +	if (ret < 0)
> +		return ret;
> +
> +	*temp = t;
> +
> +	return 0;
> +}
> +
> +static struct thermal_zone_of_device_ops hwmon_thermal_ops = {
> +	.get_temp = hwmon_thermal_get_temp,
> +};
> +
> +static int hwmon_thermal_add_sensor(struct device *dev,
> +				    struct hwmon_device *hwdev,
> +				    int index)
> +{
> +	struct hwmon_thermal_data *tdata;
> +
> +	tdata = devm_kzalloc(dev, sizeof(*tdata), GFP_KERNEL);
> +	if (!tdata)
> +		return -ENOMEM;
> +
> +	tdata->hwdev = hwdev;
> +	tdata->index = index;
> +
> +	devm_thermal_zone_of_sensor_register(&hwdev->dev, index, tdata,
> +					     &hwmon_thermal_ops);
> +
> +	return 0;
> +}
> +
> +/* sysfs attribute management */
> +
> +static ssize_t hwmon_attr_show(struct device *dev,
> +			       struct device_attribute *devattr, char *buf)
> +{
> +	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
> +	long val;
> +	int ret;
> +
> +	ret = hattr->ops->read(dev, hattr->type, hattr->attr, hattr->index,
> +			       &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	return sprintf(buf, "%ld\n", val);
> +}
> +
> +static ssize_t hwmon_attr_store(struct device *dev,
> +				struct device_attribute *devattr,
> +				const char *buf, size_t count)
> +{
> +	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
> +	long val;
> +	int ret;
> +
> +	ret = kstrtol(buf, 10, &val);
> +	if (ret < 0)
> +		return ret;
> +
> +	ret = hattr->ops->write(dev, hattr->type, hattr->attr, hattr->index,
> +				val);
> +	if (ret < 0)
> +		return ret;
> +
> +	return count;
> +}
> +
> +static int hwmon_attr_base(enum hwmon_sensor_types type)
> +{
> +	if (type == hwmon_in)
> +		return 0;
> +	return 1;
> +}
> +
> +static struct attribute *hwmon_genattr(struct device *dev,
> +				       const void *drvdata,
> +				       enum hwmon_sensor_types type,
> +				       u32 attr,
> +				       int index,
> +				       const char *template,
> +				       const struct hwmon_ops *ops)
> +{
> +	struct hwmon_device_attribute *hattr;
> +	struct device_attribute *dattr;
> +	struct attribute *a;
> +	umode_t mode;
> +	char *name;
> +
> +	if (!template)
> +		return ERR_PTR(-EINVAL);
> +
> +	mode = ops->is_visible(drvdata, type, attr, index);
> +	if (!mode)
> +		return ERR_PTR(-ENOENT);
> +
I've been wondering about doing something similar to this in IIO for a while
as our attributes are far to often rw when they should only be one or the
other. This is much more elegant.  We could get away with it (nasty as it is)
on the basis of no previous ABI to match where as you have to have this...
Can see this is_visible callback might get a little messy in some cases.

Actually, is is_visible a good name?  I'd think that would control whether
we can see the attribute at all.  Perhaps something like
get_filemode would be a better callback naming?

> +	if ((mode & S_IRUGO) && !ops->read)
> +		return ERR_PTR(-EINVAL);
> +	if ((mode & S_IWUGO) && !ops->write)
> +		return ERR_PTR(-EINVAL);
> +
> +	if (type == hwmon_chip) {
> +		name = (char *)template;
> +	} else {
> +		name = devm_kzalloc(dev, strlen(template) + 16, GFP_KERNEL);
> +		if (!name)
> +			return ERR_PTR(-ENOMEM);
> +		scnprintf(name, strlen(template) + 16, template,
> +			  index + hwmon_attr_base(type));
> +	}
> +
> +	hattr = devm_kzalloc(dev, sizeof(*hattr), GFP_KERNEL);
> +	if (!hattr)
> +		return ERR_PTR(-ENOMEM);
> +
> +	hattr->type = type;
> +	hattr->attr = attr;
> +	hattr->index = index;
> +	hattr->ops = ops;
> +
> +	dattr = &hattr->dev_attr;
> +	if (mode & S_IRUGO)
> +		dattr->show = hwmon_attr_show;
> +	if (mode & S_IWUGO)
> +		dattr->store = hwmon_attr_store;
Technically I think there is no need to worry about setting the store / show
when they aren't needed.  Maybe, not worth the really small savings though...
> +
> +	a = &dattr->attr;
> +	sysfs_attr_init(a);
> +	a->name = name;
> +	a->mode = mode;
> +
> +	return a;
> +}
> +
> +static const char * const hwmon_chip_attr_templates[] = {
> +	[hwmon_chip_temp_reset_history] = "temp_reset_history",
> +	[hwmon_chip_update_interval] = "update_interval",
> +	[hwmon_chip_alarms] = "alarms",
> +};
> +
> +static const char * const hwmon_temp_attr_templates[] = {
> +	[hwmon_temp_input] = "temp%d_input",
> +	[hwmon_temp_type] = "temp%d_type",
> +	[hwmon_temp_lcrit] = "temp%d_lcrit",
> +	[hwmon_temp_lcrit_hyst] = "temp%d_lcrit_hyst",
> +	[hwmon_temp_min] = "temp%d_min",
> +	[hwmon_temp_min_hyst] = "temp%d_min_hyst",
> +	[hwmon_temp_max] = "temp%d_max",
> +	[hwmon_temp_max_hyst] = "temp%d_max_hyst",
> +	[hwmon_temp_crit] = "temp%d_crit",
> +	[hwmon_temp_crit_hyst] = "temp%d_crit_hyst",
> +	[hwmon_temp_emergency] = "temp%d_emergency",
> +	[hwmon_temp_emergency_hyst] = "temp%d_emergency_hyst",
> +	[hwmon_temp_alarm] = "temp%d_alarm",
> +	[hwmon_temp_lcrit_alarm] = "temp%d_lcrit_alarm",
> +	[hwmon_temp_min_alarm] = "temp%d_min_alarm",
> +	[hwmon_temp_max_alarm] = "temp%d_max_alarm",
> +	[hwmon_temp_crit_alarm] = "temp%d_crit_alarm",
> +	[hwmon_temp_emergency_alarm] = "temp%d_emergency_alarm",
> +	[hwmon_temp_fault] = "temp%d_fault",
> +	[hwmon_temp_offset] = "temp%d_offset",
> +	[hwmon_temp_label] = "temp%d_label",
> +	[hwmon_temp_lowest] = "temp%d_lowest",
> +	[hwmon_temp_highest] = "temp%d_highest",
> +	[hwmon_temp_reset_history] = "temp%d_reset_history",
> +};
> +
> +static const char * const *__templates[] = {
> +	[hwmon_chip] = hwmon_chip_attr_templates,
> +	[hwmon_temp] = hwmon_temp_attr_templates,
> +};
> +
> +static const int __templates_size[] = {
> +	[hwmon_chip] = ARRAY_SIZE(hwmon_chip_attr_templates),
> +	[hwmon_temp] = ARRAY_SIZE(hwmon_temp_attr_templates),
> +};
> +
> +static int hwmon_num_channel_attrs(const struct hwmon_channel_info *info)
> +{
> +	int i, n;
> +
> +	for (i = n = 0; info->config[i]; i++)
> +		n += hweight32(info->config[i]);
> +
> +	return n;
> +}
> +
> +static int hwmon_genattrs(struct device *dev,
> +			  const void *drvdata,
> +			  struct attribute **attrs,
> +			  const struct hwmon_ops *ops,
> +			  const struct hwmon_channel_info *info)
> +{
> +	const char * const *templates;
> +	int template_size;
> +	int i, aindex = 0;
> +
> +	if (info->type >= ARRAY_SIZE(__templates))
> +		return -EINVAL;
> +
> +	templates = __templates[info->type];
> +	template_size = __templates_size[info->type];
> +
> +	for (i = 0; info->config[i]; i++) {
> +		u32 attr_mask = info->config[i];
> +		u32 attr;
> +
> +		while (attr_mask) {
> +			struct attribute *a;
> +
> +			attr = __ffs(attr_mask);
> +			attr_mask &= ~BIT(attr);
loop instead using the for_each_bit_set?  Tiny bit cleaner perhaps...
> +			if (attr >= template_size)
> +				return -EINVAL;
> +			a = hwmon_genattr(dev, drvdata, info->type, attr, i,
> +					  templates[attr], ops);
> +			if (IS_ERR(a)) {
> +				if (PTR_ERR(a) != -ENOENT)
> +					return PTR_ERR(a);
> +				continue;
> +			}
> +			attrs[aindex++] = a;
> +		}
> +	}
> +	return aindex;
> +}
> +
> +static struct attribute **
> +__hwmon_create_attrs(struct device *dev, const void *drvdata,
> +		     const struct hwmon_chip_info *chip)
> +{
> +	int ret, i, aindex = 0, nattrs = 0;
> +	struct attribute **attrs;
> +
> +	for (i = 0; chip->info[i]; i++)
> +		nattrs += hwmon_num_channel_attrs(chip->info[i]);
> +
> +	if (nattrs == 0)
> +		return ERR_PTR(-EINVAL);
> +
> +	attrs = devm_kcalloc(dev, nattrs + 1, sizeof(*attrs), GFP_KERNEL);
> +	if (attrs == NULL)
> +		return ERR_PTR(-ENOMEM);
> +
> +	for (i = 0; chip->info[i]; i++) {
> +		ret = hwmon_genattrs(dev, drvdata, &attrs[aindex], chip->ops,
> +				     chip->info[i]);
> +		if (ret < 0)
> +			return ERR_PTR(ret);
> +		aindex += ret;
> +	}
> +
> +	return attrs;
> +}
> +
> +static struct device *
> +__hwmon_device_register(struct device *dev, const char *name, void *drvdata,
> +			const struct hwmon_chip_info *chip,
> +			const struct attribute_group **groups)
>  {
>  	struct hwmon_device *hwdev;
> -	int err, id;
> +	struct device *hdev;
> +	int i, j, err, id;
>  
>  	/* Do not accept invalid characters in hwmon name attribute */
>  	if (name && (!strlen(name) || strpbrk(name, "-* \t\n")))
> @@ -114,28 +392,128 @@ hwmon_device_register_with_groups(struct device *dev, const char *name,
>  		goto ida_remove;
>  	}
>  
> +	hdev = &hwdev->dev;
> +
> +	if (chip && chip->ops->is_visible) {
> +		struct attribute **attrs;
> +		int ngroups = 2;
> +
> +		if (groups)
> +			for (i = 0; groups[i]; i++)
> +				ngroups++;
> +
> +		hwdev->groups = devm_kcalloc(dev, ngroups, sizeof(*groups),
> +					     GFP_KERNEL);
> +		if (hwdev->groups == NULL)
> +			return ERR_PTR(-ENOMEM);
> +
> +		attrs = __hwmon_create_attrs(dev, drvdata, chip);
> +		if (IS_ERR(attrs)) {
> +			err = PTR_ERR(attrs);
> +			goto free_hwmon;
> +		}
> +
> +		hwdev->group.attrs = attrs;
> +		ngroups = 0;
> +		hwdev->groups[ngroups++] = &hwdev->group;
> +
> +		if (groups) {
> +			for (i = 0; groups[i]; i++)
> +				hwdev->groups[ngroups++] = groups[i];
> +		}
> +
> +		hdev->groups = hwdev->groups;
> +	} else {
> +		hdev->groups = groups;
> +	}
> +
>  	hwdev->name = name;
> -	hwdev->dev.class = &hwmon_class;
> -	hwdev->dev.parent = dev;
> -	hwdev->dev.groups = groups;
> -	hwdev->dev.of_node = dev ? dev->of_node : NULL;
> -	dev_set_drvdata(&hwdev->dev, drvdata);
> -	dev_set_name(&hwdev->dev, HWMON_ID_FORMAT, id);
> -	err = device_register(&hwdev->dev);
> +	hdev->class = &hwmon_class;
> +	hdev->parent = dev;
> +	hdev->of_node = dev ? dev->of_node : NULL;
> +	hwdev->chip = chip;
> +	dev_set_drvdata(hdev, drvdata);
> +	dev_set_name(hdev, HWMON_ID_FORMAT, id);
> +	err = device_register(hdev);
>  	if (err)
> -		goto free;
> +		goto free_hwmon;
> +
> +	if (chip && chip->ops->is_visible && chip->ops->read &&
> +	    chip->info[0]->type == hwmon_chip &&
> +	    (chip->info[0]->config[0] & HWMON_C_REGISTER_TZ)) {
> +		const struct hwmon_channel_info **info = chip->info;
> +
> +		for (i = 1; info[i]; i++) {
> +			if (info[i]->type != hwmon_temp)
> +				continue;
> +
> +			for (j = 0; info[i]->config[j]; j++) {
> +				if (!chip->ops->is_visible(drvdata, hwmon_temp,
> +							   hwmon_temp_input, j))
> +					continue;
> +				if (info[i]->config[j] & HWMON_T_INPUT)
> +					hwmon_thermal_add_sensor(dev, hwdev, j);
> +			}
> +		}
> +	}
>  
> -	return &hwdev->dev;
> +	return hdev;
>  
> -free:
> +free_hwmon:
>  	kfree(hwdev);
>  ida_remove:
>  	ida_simple_remove(&hwmon_ida, id);
>  	return ERR_PTR(err);
>  }
> +
> +/**
> + * hwmon_device_register_with_groups - register w/ hwmon
> + * @dev: the parent device
> + * @name: hwmon name attribute
> + * @drvdata: driver data to attach to created device
> + * @groups: List of attribute groups to create
> + *
> + * hwmon_device_unregister() must be called when the device is no
> + * longer needed.
> + *
> + * Returns the pointer to the new device.
> + */
> +struct device *
> +hwmon_device_register_with_groups(struct device *dev, const char *name,
> +				  void *drvdata,
> +				  const struct attribute_group **groups)
> +{
> +	return __hwmon_device_register(dev, name, drvdata, NULL, groups);
> +}
>  EXPORT_SYMBOL_GPL(hwmon_device_register_with_groups);
>  
>  /**
> + * hwmon_device_register_with_info - register w/ hwmon
> + * @dev: the parent device
> + * @name: hwmon name attribute
> + * @drvdata: driver data to attach to created device
> + * @info: Pointer to hwmon chip information
> + * @groups - pointer to list of driver specific attribute groups
> + *
> + * hwmon_device_unregister() must be called when the device is no
> + * longer needed.
> + *
> + * Returns the pointer to the new device.
> + */
> +struct device *
> +hwmon_device_register_with_info(struct device *dev, const char *name,
> +				  void *drvdata,
> +				  const struct hwmon_chip_info *chip,
> +				  const struct attribute_group **groups)
> +{
> +	if (chip && (!chip->ops || !chip->info))
> +		return ERR_PTR(-EINVAL);
> +
> +	return __hwmon_device_register(dev, name, drvdata, chip, groups);
> +}
> +EXPORT_SYMBOL_GPL(hwmon_device_register_with_info);
> +
> +/**
>   * hwmon_device_register - register w/ hwmon
>   * @dev: the device to register
>   *
> @@ -213,6 +591,47 @@ error:
>  }
>  EXPORT_SYMBOL_GPL(devm_hwmon_device_register_with_groups);
>  
> +/**
> + * devm_hwmon_device_register_with_info - register w/ hwmon
> + * @dev: the parent device
> + * @name: hwmon name attribute
> + * @drvdata: driver data to attach to created device
> + * @info: Pointer to hwmon chip information
> + * @groups - pointer to list of driver specific attribute groups
> + *
> + * Returns the pointer to the new device. The new device is automatically
> + * unregistered with the parent device.
> + */
> +struct device *
> +devm_hwmon_device_register_with_info(struct device *dev, const char *name,
> +				     void *drvdata,
> +				     const struct hwmon_chip_info *chip,
> +				     const struct attribute_group **groups)
> +{
> +	struct device **ptr, *hwdev;
> +
> +	if (!dev)
> +		return ERR_PTR(-EINVAL);
> +
> +	ptr = devres_alloc(devm_hwmon_release, sizeof(*ptr), GFP_KERNEL);
> +	if (!ptr)
> +		return ERR_PTR(-ENOMEM);
> +
> +	hwdev = hwmon_device_register_with_info(dev, name, drvdata, chip,
> +						groups);
> +	if (IS_ERR(hwdev))
> +		goto error;
> +
> +	*ptr = hwdev;
> +	devres_add(dev, ptr);
Perhaps a blank line here? (really tiny improvement in readability?
> +	return hwdev;
> +
> +error:
> +	devres_free(ptr);
> +	return hwdev;
> +}
> +EXPORT_SYMBOL_GPL(devm_hwmon_device_register_with_info);
> +
>  static int devm_hwmon_match(struct device *dev, void *res, void *data)
>  {
>  	struct device **hwdev = res;
> diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
> index 09354f6c1d63..99250ad092fd 100644
> --- a/include/linux/hwmon.h
> +++ b/include/linux/hwmon.h
> @@ -14,9 +14,121 @@
>  #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.
> + *		Optional.
> + * @read:       Read callback. Optional.
I'd like to see a little more expansion in this comment on the form of the
callbacks.  What are the parameters etc?  I'd expect to look here first
to find that out rather than diving into docs.
> + * @write:	Write callback. Optional.
> + */
> +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);
> +};
> +
> +/**
> + * 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;
Hmm. Be very careful about running out of space. I did much the same
in IIO as you know and am somewhat regretting it now a using a bitmap is
lovely and efficient, but really annoying once you run out of bits
if you've used a fixed (short) length..

Using a bitmap as defined in bitmap.h doesn't work as there is no elegant
way of statically defining them beyond the first long.  I really wish
there was a way of doing this but can't figure out how..

Maybe just go for a u64 from the start (though that then complicates the
use of some of the bitops stuff) I suspect we'll be jumping to
that in IIO fairly soon and it'd be a lot less painful to start there
perhaps...


> +};
> +
> +/**
> + * Chip configuration
> + * @ops:	Pointer to hwmon operations.
> + * @info:	Null-terminated list of channel information.
Drop the bonus blank line.

We tossed up in IIO for a long time on whether to use a null terminated list
of our equivalent info elements, or an explict count.  Ended up with count
as it often allows sharing of the big array of channel info structures
between different parts where one part adds more hardware over the other..

I'm not saying that the gain by doing that was all that signficant, but
I thought I'd mention the trade offs.
Here I think you have made the right decision.
> + *
> + */
> +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 +138,16 @@ 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);
> 

Re: [PATCH 7/7] hwmon: (core) Document new kernel API

[Jonathan Cameron]

On 26/06/16 04:26, Guenter Roeck wrote:
> Describe the new registration API function as well as the data
> structures it requires.
> 
> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Nice docs. Couple of typos inline.

Jonathan
> ---
>  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..1a96c36532f2 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 priovided if any writeable attributes exist.
provided
> +
> +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 atributes. Only non-standard
attributes
> +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.
> 

Re: [PATCH 0/5] hwmon: New hwmon registration API

[Jonathan Cameron]

On 26/06/16 04:26, Guenter Roeck wrote:
> 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 introduces the API as well as support
> for temperature sensors. Subsequent patches introduce support for
> voltage, current, power, energy, humidity, and fan speed sensors.
> 
> The series was tested by converting several drivers (lm75, lm90, tmp102,
> tmp421, ltc4245) to the new API. Testing was done with with real chips
> as well as with the hwmon driver module test code available at
> https://github.com/groeck/module-tests.
Some cool stuff hiding in there :)

I've only reviewed 1 and 7 and the intermediate ones are really either
correct or they aren't and they look fine to me.


So what's next? (beyond presumably a lot of driver conversions).

Jonathan
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> 

Re: [PATCH 0/5] hwmon: New hwmon registration API

[Guenter Roeck]

Hi Jonathan,

On 07/10/2016 09:00 AM, Jonathan Cameron wrote:
> On 26/06/16 04:26, Guenter Roeck wrote:
>> 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 introduces the API as well as support
>> for temperature sensors. Subsequent patches introduce support for
>> voltage, current, power, energy, humidity, and fan speed sensors.
>>
>> The series was tested by converting several drivers (lm75, lm90, tmp102,
>> tmp421, ltc4245) to the new API. Testing was done with with real chips
>> as well as with the hwmon driver module test code available at
>> https://github.com/groeck/module-tests.
> Some cool stuff hiding in there :)
>
> I've only reviewed 1 and 7 and the intermediate ones are really either
> correct or they aren't and they look fine to me.
>
Thanks a lot for your feedback - it is reassuring that it looks sane to you.

>
> So what's next? (beyond presumably a lot of driver conversions).
>
Next steps will be to address your comments, re-test, submit a new series,
add to -next after v4.8-rc1 is out, submit the conversions I have done
and add to -next. Then, obviously, only accept new drivers using the
new API.

Not sure if there is anything else we can or want to do do at this time.
Do you have anything in mind ?

Thanks,
Guenter

Re: [PATCH 0/5] hwmon: New hwmon registration API

[Guenter Roeck]

Hi Jonathan,

On 07/10/2016 09:00 AM, Jonathan Cameron wrote:
> On 26/06/16 04:26, Guenter Roeck wrote:
>> 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 introduces the API as well as support
>> for temperature sensors. Subsequent patches introduce support for
>> voltage, current, power, energy, humidity, and fan speed sensors.
>>
>> The series was tested by converting several drivers (lm75, lm90, tmp102,
>> tmp421, ltc4245) to the new API. Testing was done with with real chips
>> as well as with the hwmon driver module test code available at
>> https://github.com/groeck/module-tests.
> Some cool stuff hiding in there :)
>
> I've only reviewed 1 and 7 and the intermediate ones are really either
> correct or they aren't and they look fine to me.
>
Thanks a lot for your feedback - it is reassuring that it looks sane to you.

>
> So what's next? (beyond presumably a lot of driver conversions).
>
Next steps will be to address your comments, re-test, submit a new series,
add to -next after v4.8-rc1 is out, submit the conversions I have done
and add to -next. Then, obviously, only accept new drivers using the
new API.

Not sure if there is anything else we can or want to do do at this time.
Do you have anything in mind ?

Thanks,
Guenter

Re: [PATCH 1/7] hwmon: (core) New hwmon registration API

[Guenter Roeck]

Hi Jonathan,

On 07/10/2016 08:51 AM, Jonathan Cameron wrote:
> On 26/06/16 04:26, Guenter Roeck wrote:
>> 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 size is typically reduced by 20-50% 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.
>>
>> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
> Hi Guenter.
>
> Sorry it took me so long to get to this....
>
> Anyhow, mostly looks clean, effective and consise to me.
> Various bits and pieces inline.  There are a few bits I might (when time
> allows) lift over to iio as they are nicer than what we have.
>
> My one lesson learned from IIO is always be wary of space in bitmaps.  We
> haven't run out yet but are getting close.  You may end up in a similar
> state here a few years down the line.
>
Yes, I spend a lot of time arguing with myself over u32 vs. u64. I decided
to stick with u32 for now, reasons being that there are multiple number spaces
and that the bit mask is only really used for registration (and thus relatively
easy to change).

More comments inline.

> Jonathan
>> ---
>>   drivers/hwmon/hwmon.c | 485 ++++++++++++++++++++++++++++++++++++++++++++++----
>>   include/linux/hwmon.h | 122 +++++++++++++
>>   2 files changed, 574 insertions(+), 33 deletions(-)
>>
>> diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
>> index a26c385a435b..9530644ae297 100644
>> --- a/drivers/hwmon/hwmon.c
>> +++ b/drivers/hwmon/hwmon.c
>> @@ -12,17 +12,16 @@
>>
>>   #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>>
>> -#include <linux/module.h>
>> +#include <linux/bitops.h>
>>   #include <linux/device.h>
>>   #include <linux/err.h>
>> -#include <linux/slab.h>
>> -#include <linux/kdev_t.h>
>> -#include <linux/idr.h>
>>   #include <linux/hwmon.h>
>> -#include <linux/gfp.h>
>> -#include <linux/spinlock.h>
>> +#include <linux/idr.h>
>> +#include <linux/module.h>
> Some unconnected changes in this.  Arguably reordering is good and
> all but should be in a precursor patch so it's obvious what has
> been added or removed here.
>
Split into a separate patch.

>>   #include <linux/pci.h>
>> +#include <linux/slab.h>
>>   #include <linux/string.h>
>> +#include <linux/thermal.h>
>>
>>   #define HWMON_ID_PREFIX "hwmon"
>>   #define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
>> @@ -30,9 +29,33 @@
>>   struct hwmon_device {
>>   	const char *name;
>>   	struct device dev;
>> +	const struct hwmon_chip_info *chip;
>> +
>> +	struct attribute_group group;
>> +	const struct attribute_group **groups;
>>   };
>>   #define to_hwmon_device(d) container_of(d, struct hwmon_device, dev)
>>
>> +struct hwmon_device_attribute {
>> +	struct device_attribute dev_attr;
>> +	const struct hwmon_ops *ops;
>> +	enum hwmon_sensor_types type;
>> +	u32 attr;
>> +	int index;
>> +};
>> +#define to_hwmon_attr(d) \
>> +	container_of(d, struct hwmon_device_attribute, dev_attr)
>> +
>> +/*
>> + * Thermal zone information
>> + * In addition to the reference to the hwmon device,
>> + * also provides the sensor index.
>> + */
>> +struct hwmon_thermal_data {
>> +	struct hwmon_device *hwdev;	/* Reference to hwmon device */
>> +	int index;			/* sensor index */
>> +};
>> +
>>   static ssize_t
>>   show_name(struct device *dev, struct device_attribute *attr, char *buf)
>>   {
>> @@ -80,25 +103,280 @@ static struct class hwmon_class = {
>>
>>   static DEFINE_IDA(hwmon_ida);
>>
>> -/**
>> - * hwmon_device_register_with_groups - register w/ hwmon
>> - * @dev: the parent device
>> - * @name: hwmon name attribute
>> - * @drvdata: driver data to attach to created device
>> - * @groups: List of attribute groups to create
>> - *
>> - * hwmon_device_unregister() must be called when the device is no
>> - * longer needed.
>> - *
>> - * Returns the pointer to the new device.
>> - */
>> -struct device *
>> -hwmon_device_register_with_groups(struct device *dev, const char *name,
>> -				  void *drvdata,
>> -				  const struct attribute_group **groups)
>> +/* Thermal zone handling */
>> +
>> +static int hwmon_thermal_get_temp(void *data, int *temp)
>> +{
>> +	struct hwmon_thermal_data *tdata = data;
>> +	struct hwmon_device *hwdev = tdata->hwdev;
>> +	int ret;
>> +	long t;
>> +
>> +	ret = hwdev->chip->ops->read(&hwdev->dev, hwmon_temp, hwmon_temp_input,
>> +				     tdata->index, &t);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	*temp = t;
>> +
>> +	return 0;
>> +}
>> +
>> +static struct thermal_zone_of_device_ops hwmon_thermal_ops = {
>> +	.get_temp = hwmon_thermal_get_temp,
>> +};
>> +
>> +static int hwmon_thermal_add_sensor(struct device *dev,
>> +				    struct hwmon_device *hwdev,
>> +				    int index)
>> +{
>> +	struct hwmon_thermal_data *tdata;
>> +
>> +	tdata = devm_kzalloc(dev, sizeof(*tdata), GFP_KERNEL);
>> +	if (!tdata)
>> +		return -ENOMEM;
>> +
>> +	tdata->hwdev = hwdev;
>> +	tdata->index = index;
>> +
>> +	devm_thermal_zone_of_sensor_register(&hwdev->dev, index, tdata,
>> +					     &hwmon_thermal_ops);
>> +
>> +	return 0;
>> +}
>> +
>> +/* sysfs attribute management */
>> +
>> +static ssize_t hwmon_attr_show(struct device *dev,
>> +			       struct device_attribute *devattr, char *buf)
>> +{
>> +	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
>> +	long val;
>> +	int ret;
>> +
>> +	ret = hattr->ops->read(dev, hattr->type, hattr->attr, hattr->index,
>> +			       &val);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return sprintf(buf, "%ld\n", val);
>> +}
>> +
>> +static ssize_t hwmon_attr_store(struct device *dev,
>> +				struct device_attribute *devattr,
>> +				const char *buf, size_t count)
>> +{
>> +	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
>> +	long val;
>> +	int ret;
>> +
>> +	ret = kstrtol(buf, 10, &val);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	ret = hattr->ops->write(dev, hattr->type, hattr->attr, hattr->index,
>> +				val);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return count;
>> +}
>> +
>> +static int hwmon_attr_base(enum hwmon_sensor_types type)
>> +{
>> +	if (type == hwmon_in)
>> +		return 0;
>> +	return 1;
>> +}
>> +
>> +static struct attribute *hwmon_genattr(struct device *dev,
>> +				       const void *drvdata,
>> +				       enum hwmon_sensor_types type,
>> +				       u32 attr,
>> +				       int index,
>> +				       const char *template,
>> +				       const struct hwmon_ops *ops)
>> +{
>> +	struct hwmon_device_attribute *hattr;
>> +	struct device_attribute *dattr;
>> +	struct attribute *a;
>> +	umode_t mode;
>> +	char *name;
>> +
>> +	if (!template)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	mode = ops->is_visible(drvdata, type, attr, index);
>> +	if (!mode)
>> +		return ERR_PTR(-ENOENT);
>> +
> I've been wondering about doing something similar to this in IIO for a while
> as our attributes are far to often rw when they should only be one or the
> other. This is much more elegant.  We could get away with it (nasty as it is)
> on the basis of no previous ABI to match where as you have to have this...
> Can see this is_visible callback might get a little messy in some cases.
>
So far it wasn't that bad. For chips supporting multiple sensor types,
I found it useful to have per-type functions in the driver. I also thought about
using per-type callbacks, but decided against it to avoid large (and mostly
empty) data structures in the driver. Also, hwmon drivers always had to deal with
this situation, so the code to determine sensor visibility is already there
(either by implementing the is_visible callback in struct attribute_group,
or by dynamically selecting which attribute groups are needed in the probe
function).

> Actually, is is_visible a good name?  I'd think that would control whether
> we can see the attribute at all.  Perhaps something like
> get_filemode would be a better callback naming?
>
I picked is_visible because that is the name used in struct attribute_group,
and it has the same functionality there.

>> +	if ((mode & S_IRUGO) && !ops->read)
>> +		return ERR_PTR(-EINVAL);
>> +	if ((mode & S_IWUGO) && !ops->write)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	if (type == hwmon_chip) {
>> +		name = (char *)template;
>> +	} else {
>> +		name = devm_kzalloc(dev, strlen(template) + 16, GFP_KERNEL);
>> +		if (!name)
>> +			return ERR_PTR(-ENOMEM);
>> +		scnprintf(name, strlen(template) + 16, template,
>> +			  index + hwmon_attr_base(type));
>> +	}
>> +
>> +	hattr = devm_kzalloc(dev, sizeof(*hattr), GFP_KERNEL);
>> +	if (!hattr)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	hattr->type = type;
>> +	hattr->attr = attr;
>> +	hattr->index = index;
>> +	hattr->ops = ops;
>> +
>> +	dattr = &hattr->dev_attr;
>> +	if (mode & S_IRUGO)
>> +		dattr->show = hwmon_attr_show;
>> +	if (mode & S_IWUGO)
>> +		dattr->store = hwmon_attr_store;
> Technically I think there is no need to worry about setting the store / show
> when they aren't needed.  Maybe, not worth the really small savings though...

Yes, you are right. Not to save some code, but the if statements are really not
necessary and don't add any value.

>> +
>> +	a = &dattr->attr;
>> +	sysfs_attr_init(a);
>> +	a->name = name;
>> +	a->mode = mode;
>> +
>> +	return a;
>> +}
>> +
>> +static const char * const hwmon_chip_attr_templates[] = {
>> +	[hwmon_chip_temp_reset_history] = "temp_reset_history",
>> +	[hwmon_chip_update_interval] = "update_interval",
>> +	[hwmon_chip_alarms] = "alarms",
>> +};
>> +
>> +static const char * const hwmon_temp_attr_templates[] = {
>> +	[hwmon_temp_input] = "temp%d_input",
>> +	[hwmon_temp_type] = "temp%d_type",
>> +	[hwmon_temp_lcrit] = "temp%d_lcrit",
>> +	[hwmon_temp_lcrit_hyst] = "temp%d_lcrit_hyst",
>> +	[hwmon_temp_min] = "temp%d_min",
>> +	[hwmon_temp_min_hyst] = "temp%d_min_hyst",
>> +	[hwmon_temp_max] = "temp%d_max",
>> +	[hwmon_temp_max_hyst] = "temp%d_max_hyst",
>> +	[hwmon_temp_crit] = "temp%d_crit",
>> +	[hwmon_temp_crit_hyst] = "temp%d_crit_hyst",
>> +	[hwmon_temp_emergency] = "temp%d_emergency",
>> +	[hwmon_temp_emergency_hyst] = "temp%d_emergency_hyst",
>> +	[hwmon_temp_alarm] = "temp%d_alarm",
>> +	[hwmon_temp_lcrit_alarm] = "temp%d_lcrit_alarm",
>> +	[hwmon_temp_min_alarm] = "temp%d_min_alarm",
>> +	[hwmon_temp_max_alarm] = "temp%d_max_alarm",
>> +	[hwmon_temp_crit_alarm] = "temp%d_crit_alarm",
>> +	[hwmon_temp_emergency_alarm] = "temp%d_emergency_alarm",
>> +	[hwmon_temp_fault] = "temp%d_fault",
>> +	[hwmon_temp_offset] = "temp%d_offset",
>> +	[hwmon_temp_label] = "temp%d_label",
>> +	[hwmon_temp_lowest] = "temp%d_lowest",
>> +	[hwmon_temp_highest] = "temp%d_highest",
>> +	[hwmon_temp_reset_history] = "temp%d_reset_history",
>> +};
>> +
>> +static const char * const *__templates[] = {
>> +	[hwmon_chip] = hwmon_chip_attr_templates,
>> +	[hwmon_temp] = hwmon_temp_attr_templates,
>> +};
>> +
>> +static const int __templates_size[] = {
>> +	[hwmon_chip] = ARRAY_SIZE(hwmon_chip_attr_templates),
>> +	[hwmon_temp] = ARRAY_SIZE(hwmon_temp_attr_templates),
>> +};
>> +
>> +static int hwmon_num_channel_attrs(const struct hwmon_channel_info *info)
>> +{
>> +	int i, n;
>> +
>> +	for (i = n = 0; info->config[i]; i++)
>> +		n += hweight32(info->config[i]);
>> +
>> +	return n;
>> +}
>> +
>> +static int hwmon_genattrs(struct device *dev,
>> +			  const void *drvdata,
>> +			  struct attribute **attrs,
>> +			  const struct hwmon_ops *ops,
>> +			  const struct hwmon_channel_info *info)
>> +{
>> +	const char * const *templates;
>> +	int template_size;
>> +	int i, aindex = 0;
>> +
>> +	if (info->type >= ARRAY_SIZE(__templates))
>> +		return -EINVAL;
>> +
>> +	templates = __templates[info->type];
>> +	template_size = __templates_size[info->type];
>> +
>> +	for (i = 0; info->config[i]; i++) {
>> +		u32 attr_mask = info->config[i];
>> +		u32 attr;
>> +
>> +		while (attr_mask) {
>> +			struct attribute *a;
>> +
>> +			attr = __ffs(attr_mask);
>> +			attr_mask &= ~BIT(attr);
> loop instead using the for_each_bit_set?  Tiny bit cleaner perhaps...

A bit, maybe, though not much. I changed it, but since for_each_set_bit() requires
a pointer to an unsigned long as argument, I still need attr_mask as temporary
variable (I don't want to use unsigned long for the config bit mask since
its size is not well defined). Hmm ... that also means that switching to u64
in the future will be tricky. I'll need to think about that some more.

>> +			if (attr >= template_size)
>> +				return -EINVAL;
>> +			a = hwmon_genattr(dev, drvdata, info->type, attr, i,
>> +					  templates[attr], ops);
>> +			if (IS_ERR(a)) {
>> +				if (PTR_ERR(a) != -ENOENT)
>> +					return PTR_ERR(a);
>> +				continue;
>> +			}
>> +			attrs[aindex++] = a;
>> +		}
>> +	}
>> +	return aindex;
>> +}
>> +
>> +static struct attribute **
>> +__hwmon_create_attrs(struct device *dev, const void *drvdata,
>> +		     const struct hwmon_chip_info *chip)
>> +{
>> +	int ret, i, aindex = 0, nattrs = 0;
>> +	struct attribute **attrs;
>> +
>> +	for (i = 0; chip->info[i]; i++)
>> +		nattrs += hwmon_num_channel_attrs(chip->info[i]);
>> +
>> +	if (nattrs == 0)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	attrs = devm_kcalloc(dev, nattrs + 1, sizeof(*attrs), GFP_KERNEL);
>> +	if (attrs == NULL)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	for (i = 0; chip->info[i]; i++) {
>> +		ret = hwmon_genattrs(dev, drvdata, &attrs[aindex], chip->ops,
>> +				     chip->info[i]);
>> +		if (ret < 0)
>> +			return ERR_PTR(ret);
>> +		aindex += ret;
>> +	}
>> +
>> +	return attrs;
>> +}
>> +
>> +static struct device *
>> +__hwmon_device_register(struct device *dev, const char *name, void *drvdata,
>> +			const struct hwmon_chip_info *chip,
>> +			const struct attribute_group **groups)
>>   {
>>   	struct hwmon_device *hwdev;
>> -	int err, id;
>> +	struct device *hdev;
>> +	int i, j, err, id;
>>
>>   	/* Do not accept invalid characters in hwmon name attribute */
>>   	if (name && (!strlen(name) || strpbrk(name, "-* \t\n")))
>> @@ -114,28 +392,128 @@ hwmon_device_register_with_groups(struct device *dev, const char *name,
>>   		goto ida_remove;
>>   	}
>>
>> +	hdev = &hwdev->dev;
>> +
>> +	if (chip && chip->ops->is_visible) {
>> +		struct attribute **attrs;
>> +		int ngroups = 2;
>> +
>> +		if (groups)
>> +			for (i = 0; groups[i]; i++)
>> +				ngroups++;
>> +
>> +		hwdev->groups = devm_kcalloc(dev, ngroups, sizeof(*groups),
>> +					     GFP_KERNEL);
>> +		if (hwdev->groups == NULL)
>> +			return ERR_PTR(-ENOMEM);
>> +
>> +		attrs = __hwmon_create_attrs(dev, drvdata, chip);
>> +		if (IS_ERR(attrs)) {
>> +			err = PTR_ERR(attrs);
>> +			goto free_hwmon;
>> +		}
>> +
>> +		hwdev->group.attrs = attrs;
>> +		ngroups = 0;
>> +		hwdev->groups[ngroups++] = &hwdev->group;
>> +
>> +		if (groups) {
>> +			for (i = 0; groups[i]; i++)
>> +				hwdev->groups[ngroups++] = groups[i];
>> +		}
>> +
>> +		hdev->groups = hwdev->groups;
>> +	} else {
>> +		hdev->groups = groups;
>> +	}
>> +
>>   	hwdev->name = name;
>> -	hwdev->dev.class = &hwmon_class;
>> -	hwdev->dev.parent = dev;
>> -	hwdev->dev.groups = groups;
>> -	hwdev->dev.of_node = dev ? dev->of_node : NULL;
>> -	dev_set_drvdata(&hwdev->dev, drvdata);
>> -	dev_set_name(&hwdev->dev, HWMON_ID_FORMAT, id);
>> -	err = device_register(&hwdev->dev);
>> +	hdev->class = &hwmon_class;
>> +	hdev->parent = dev;
>> +	hdev->of_node = dev ? dev->of_node : NULL;
>> +	hwdev->chip = chip;
>> +	dev_set_drvdata(hdev, drvdata);
>> +	dev_set_name(hdev, HWMON_ID_FORMAT, id);
>> +	err = device_register(hdev);
>>   	if (err)
>> -		goto free;
>> +		goto free_hwmon;
>> +
>> +	if (chip && chip->ops->is_visible && chip->ops->read &&
>> +	    chip->info[0]->type == hwmon_chip &&
>> +	    (chip->info[0]->config[0] & HWMON_C_REGISTER_TZ)) {
>> +		const struct hwmon_channel_info **info = chip->info;
>> +
>> +		for (i = 1; info[i]; i++) {
>> +			if (info[i]->type != hwmon_temp)
>> +				continue;
>> +
>> +			for (j = 0; info[i]->config[j]; j++) {
>> +				if (!chip->ops->is_visible(drvdata, hwmon_temp,
>> +							   hwmon_temp_input, j))
>> +					continue;
>> +				if (info[i]->config[j] & HWMON_T_INPUT)
>> +					hwmon_thermal_add_sensor(dev, hwdev, j);
>> +			}
>> +		}
>> +	}
>>
>> -	return &hwdev->dev;
>> +	return hdev;
>>
>> -free:
>> +free_hwmon:
>>   	kfree(hwdev);
>>   ida_remove:
>>   	ida_simple_remove(&hwmon_ida, id);
>>   	return ERR_PTR(err);
>>   }
>> +
>> +/**
>> + * hwmon_device_register_with_groups - register w/ hwmon
>> + * @dev: the parent device
>> + * @name: hwmon name attribute
>> + * @drvdata: driver data to attach to created device
>> + * @groups: List of attribute groups to create
>> + *
>> + * hwmon_device_unregister() must be called when the device is no
>> + * longer needed.
>> + *
>> + * Returns the pointer to the new device.
>> + */
>> +struct device *
>> +hwmon_device_register_with_groups(struct device *dev, const char *name,
>> +				  void *drvdata,
>> +				  const struct attribute_group **groups)
>> +{
>> +	return __hwmon_device_register(dev, name, drvdata, NULL, groups);
>> +}
>>   EXPORT_SYMBOL_GPL(hwmon_device_register_with_groups);
>>
>>   /**
>> + * hwmon_device_register_with_info - register w/ hwmon
>> + * @dev: the parent device
>> + * @name: hwmon name attribute
>> + * @drvdata: driver data to attach to created device
>> + * @info: Pointer to hwmon chip information
>> + * @groups - pointer to list of driver specific attribute groups
>> + *
>> + * hwmon_device_unregister() must be called when the device is no
>> + * longer needed.
>> + *
>> + * Returns the pointer to the new device.
>> + */
>> +struct device *
>> +hwmon_device_register_with_info(struct device *dev, const char *name,
>> +				  void *drvdata,
>> +				  const struct hwmon_chip_info *chip,
>> +				  const struct attribute_group **groups)
>> +{
>> +	if (chip && (!chip->ops || !chip->info))
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	return __hwmon_device_register(dev, name, drvdata, chip, groups);
>> +}
>> +EXPORT_SYMBOL_GPL(hwmon_device_register_with_info);
>> +
>> +/**
>>    * hwmon_device_register - register w/ hwmon
>>    * @dev: the device to register
>>    *
>> @@ -213,6 +591,47 @@ error:
>>   }
>>   EXPORT_SYMBOL_GPL(devm_hwmon_device_register_with_groups);
>>
>> +/**
>> + * devm_hwmon_device_register_with_info - register w/ hwmon
>> + * @dev: the parent device
>> + * @name: hwmon name attribute
>> + * @drvdata: driver data to attach to created device
>> + * @info: Pointer to hwmon chip information
>> + * @groups - pointer to list of driver specific attribute groups
>> + *
>> + * Returns the pointer to the new device. The new device is automatically
>> + * unregistered with the parent device.
>> + */
>> +struct device *
>> +devm_hwmon_device_register_with_info(struct device *dev, const char *name,
>> +				     void *drvdata,
>> +				     const struct hwmon_chip_info *chip,
>> +				     const struct attribute_group **groups)
>> +{
>> +	struct device **ptr, *hwdev;
>> +
>> +	if (!dev)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	ptr = devres_alloc(devm_hwmon_release, sizeof(*ptr), GFP_KERNEL);
>> +	if (!ptr)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	hwdev = hwmon_device_register_with_info(dev, name, drvdata, chip,
>> +						groups);
>> +	if (IS_ERR(hwdev))
>> +		goto error;
>> +
>> +	*ptr = hwdev;
>> +	devres_add(dev, ptr);
> Perhaps a blank line here? (really tiny improvement in readability?
>> +	return hwdev;
>> +
>> +error:
>> +	devres_free(ptr);
>> +	return hwdev;
>> +}
>> +EXPORT_SYMBOL_GPL(devm_hwmon_device_register_with_info);
>> +
>>   static int devm_hwmon_match(struct device *dev, void *res, void *data)
>>   {
>>   	struct device **hwdev = res;
>> diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
>> index 09354f6c1d63..99250ad092fd 100644
>> --- a/include/linux/hwmon.h
>> +++ b/include/linux/hwmon.h
>> @@ -14,9 +14,121 @@
>>   #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.
>> + *		Optional.
>> + * @read:       Read callback. Optional.
> I'd like to see a little more expansion in this comment on the form of the
> callbacks.  What are the parameters etc?  I'd expect to look here first
> to find that out rather than diving into docs.

Done.

>> + * @write:	Write callback. Optional.
>> + */
>> +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);
>> +};
>> +
>> +/**
>> + * 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;
> Hmm. Be very careful about running out of space. I did much the same
> in IIO as you know and am somewhat regretting it now a using a bitmap is
> lovely and efficient, but really annoying once you run out of bits
> if you've used a fixed (short) length..
>
> Using a bitmap as defined in bitmap.h doesn't work as there is no elegant
> way of statically defining them beyond the first long.  I really wish
> there was a way of doing this but can't figure out how..
>
Me not either, which is why I did not use it.

> Maybe just go for a u64 from the start (though that then complicates the
> use of some of the bitops stuff) I suspect we'll be jumping to
> that in IIO fairly soon and it'd be a lot less painful to start there
> perhaps...
>
My solution trying to avoid that was to use separate number spaces
for the different sensor types. If/when we hit the limit (temperatures
are getting close), we would have two options: Define a new sensor type
to handle the overflow, or switch to u64. Ultimately I decided to stick
with u32 for now because u64 seemed overkill. On the other side, I made
that decision when the read/write/is_visible API to the drivers included
the bit mask, which is no longer the case. Maybe I'll try with u64 to see
its impact on code size.

>
>> +};
>> +
>> +/**
>> + * Chip configuration
>> + * @ops:	Pointer to hwmon operations.
>> + * @info:	Null-terminated list of channel information.
> Drop the bonus blank line.
>
> We tossed up in IIO for a long time on whether to use a null terminated list
> of our equivalent info elements, or an explict count.  Ended up with count
> as it often allows sharing of the big array of channel info structures
> between different parts where one part adds more hardware over the other..
>
> I'm not saying that the gain by doing that was all that signficant, but
> I thought I'd mention the trade offs.

I went through the same thinking process. At the end, I decided to go with
the terminated list since passing it around seemed to be simpler.
The core has to walk through the list anyway, and the hwmon code does not
require big data structures to describe the channels.

> Here I think you have made the right decision.

Thanks for the feedback, and thanks a lot for your time!

Guenter

Re: [PATCH 1/7] hwmon: (core) New hwmon registration API

[Guenter Roeck]

Hi Jonathan,

On 07/10/2016 08:51 AM, Jonathan Cameron wrote:
> On 26/06/16 04:26, Guenter Roeck wrote:
>> 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 size is typically reduced by 20-50% 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.
>>
>> Signed-off-by: Guenter Roeck <linux-0h96xk9xTtrk1uMJSBkQmQ@public.gmane.org>
> Hi Guenter.
>
> Sorry it took me so long to get to this....
>
> Anyhow, mostly looks clean, effective and consise to me.
> Various bits and pieces inline.  There are a few bits I might (when time
> allows) lift over to iio as they are nicer than what we have.
>
> My one lesson learned from IIO is always be wary of space in bitmaps.  We
> haven't run out yet but are getting close.  You may end up in a similar
> state here a few years down the line.
>
Yes, I spend a lot of time arguing with myself over u32 vs. u64. I decided
to stick with u32 for now, reasons being that there are multiple number spaces
and that the bit mask is only really used for registration (and thus relatively
easy to change).

More comments inline.

> Jonathan
>> ---
>>   drivers/hwmon/hwmon.c | 485 ++++++++++++++++++++++++++++++++++++++++++++++----
>>   include/linux/hwmon.h | 122 +++++++++++++
>>   2 files changed, 574 insertions(+), 33 deletions(-)
>>
>> diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
>> index a26c385a435b..9530644ae297 100644
>> --- a/drivers/hwmon/hwmon.c
>> +++ b/drivers/hwmon/hwmon.c
>> @@ -12,17 +12,16 @@
>>
>>   #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
>>
>> -#include <linux/module.h>
>> +#include <linux/bitops.h>
>>   #include <linux/device.h>
>>   #include <linux/err.h>
>> -#include <linux/slab.h>
>> -#include <linux/kdev_t.h>
>> -#include <linux/idr.h>
>>   #include <linux/hwmon.h>
>> -#include <linux/gfp.h>
>> -#include <linux/spinlock.h>
>> +#include <linux/idr.h>
>> +#include <linux/module.h>
> Some unconnected changes in this.  Arguably reordering is good and
> all but should be in a precursor patch so it's obvious what has
> been added or removed here.
>
Split into a separate patch.

>>   #include <linux/pci.h>
>> +#include <linux/slab.h>
>>   #include <linux/string.h>
>> +#include <linux/thermal.h>
>>
>>   #define HWMON_ID_PREFIX "hwmon"
>>   #define HWMON_ID_FORMAT HWMON_ID_PREFIX "%d"
>> @@ -30,9 +29,33 @@
>>   struct hwmon_device {
>>   	const char *name;
>>   	struct device dev;
>> +	const struct hwmon_chip_info *chip;
>> +
>> +	struct attribute_group group;
>> +	const struct attribute_group **groups;
>>   };
>>   #define to_hwmon_device(d) container_of(d, struct hwmon_device, dev)
>>
>> +struct hwmon_device_attribute {
>> +	struct device_attribute dev_attr;
>> +	const struct hwmon_ops *ops;
>> +	enum hwmon_sensor_types type;
>> +	u32 attr;
>> +	int index;
>> +};
>> +#define to_hwmon_attr(d) \
>> +	container_of(d, struct hwmon_device_attribute, dev_attr)
>> +
>> +/*
>> + * Thermal zone information
>> + * In addition to the reference to the hwmon device,
>> + * also provides the sensor index.
>> + */
>> +struct hwmon_thermal_data {
>> +	struct hwmon_device *hwdev;	/* Reference to hwmon device */
>> +	int index;			/* sensor index */
>> +};
>> +
>>   static ssize_t
>>   show_name(struct device *dev, struct device_attribute *attr, char *buf)
>>   {
>> @@ -80,25 +103,280 @@ static struct class hwmon_class = {
>>
>>   static DEFINE_IDA(hwmon_ida);
>>
>> -/**
>> - * hwmon_device_register_with_groups - register w/ hwmon
>> - * @dev: the parent device
>> - * @name: hwmon name attribute
>> - * @drvdata: driver data to attach to created device
>> - * @groups: List of attribute groups to create
>> - *
>> - * hwmon_device_unregister() must be called when the device is no
>> - * longer needed.
>> - *
>> - * Returns the pointer to the new device.
>> - */
>> -struct device *
>> -hwmon_device_register_with_groups(struct device *dev, const char *name,
>> -				  void *drvdata,
>> -				  const struct attribute_group **groups)
>> +/* Thermal zone handling */
>> +
>> +static int hwmon_thermal_get_temp(void *data, int *temp)
>> +{
>> +	struct hwmon_thermal_data *tdata = data;
>> +	struct hwmon_device *hwdev = tdata->hwdev;
>> +	int ret;
>> +	long t;
>> +
>> +	ret = hwdev->chip->ops->read(&hwdev->dev, hwmon_temp, hwmon_temp_input,
>> +				     tdata->index, &t);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	*temp = t;
>> +
>> +	return 0;
>> +}
>> +
>> +static struct thermal_zone_of_device_ops hwmon_thermal_ops = {
>> +	.get_temp = hwmon_thermal_get_temp,
>> +};
>> +
>> +static int hwmon_thermal_add_sensor(struct device *dev,
>> +				    struct hwmon_device *hwdev,
>> +				    int index)
>> +{
>> +	struct hwmon_thermal_data *tdata;
>> +
>> +	tdata = devm_kzalloc(dev, sizeof(*tdata), GFP_KERNEL);
>> +	if (!tdata)
>> +		return -ENOMEM;
>> +
>> +	tdata->hwdev = hwdev;
>> +	tdata->index = index;
>> +
>> +	devm_thermal_zone_of_sensor_register(&hwdev->dev, index, tdata,
>> +					     &hwmon_thermal_ops);
>> +
>> +	return 0;
>> +}
>> +
>> +/* sysfs attribute management */
>> +
>> +static ssize_t hwmon_attr_show(struct device *dev,
>> +			       struct device_attribute *devattr, char *buf)
>> +{
>> +	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
>> +	long val;
>> +	int ret;
>> +
>> +	ret = hattr->ops->read(dev, hattr->type, hattr->attr, hattr->index,
>> +			       &val);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return sprintf(buf, "%ld\n", val);
>> +}
>> +
>> +static ssize_t hwmon_attr_store(struct device *dev,
>> +				struct device_attribute *devattr,
>> +				const char *buf, size_t count)
>> +{
>> +	struct hwmon_device_attribute *hattr = to_hwmon_attr(devattr);
>> +	long val;
>> +	int ret;
>> +
>> +	ret = kstrtol(buf, 10, &val);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	ret = hattr->ops->write(dev, hattr->type, hattr->attr, hattr->index,
>> +				val);
>> +	if (ret < 0)
>> +		return ret;
>> +
>> +	return count;
>> +}
>> +
>> +static int hwmon_attr_base(enum hwmon_sensor_types type)
>> +{
>> +	if (type == hwmon_in)
>> +		return 0;
>> +	return 1;
>> +}
>> +
>> +static struct attribute *hwmon_genattr(struct device *dev,
>> +				       const void *drvdata,
>> +				       enum hwmon_sensor_types type,
>> +				       u32 attr,
>> +				       int index,
>> +				       const char *template,
>> +				       const struct hwmon_ops *ops)
>> +{
>> +	struct hwmon_device_attribute *hattr;
>> +	struct device_attribute *dattr;
>> +	struct attribute *a;
>> +	umode_t mode;
>> +	char *name;
>> +
>> +	if (!template)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	mode = ops->is_visible(drvdata, type, attr, index);
>> +	if (!mode)
>> +		return ERR_PTR(-ENOENT);
>> +
> I've been wondering about doing something similar to this in IIO for a while
> as our attributes are far to often rw when they should only be one or the
> other. This is much more elegant.  We could get away with it (nasty as it is)
> on the basis of no previous ABI to match where as you have to have this...
> Can see this is_visible callback might get a little messy in some cases.
>
So far it wasn't that bad. For chips supporting multiple sensor types,
I found it useful to have per-type functions in the driver. I also thought about
using per-type callbacks, but decided against it to avoid large (and mostly
empty) data structures in the driver. Also, hwmon drivers always had to deal with
this situation, so the code to determine sensor visibility is already there
(either by implementing the is_visible callback in struct attribute_group,
or by dynamically selecting which attribute groups are needed in the probe
function).

> Actually, is is_visible a good name?  I'd think that would control whether
> we can see the attribute at all.  Perhaps something like
> get_filemode would be a better callback naming?
>
I picked is_visible because that is the name used in struct attribute_group,
and it has the same functionality there.

>> +	if ((mode & S_IRUGO) && !ops->read)
>> +		return ERR_PTR(-EINVAL);
>> +	if ((mode & S_IWUGO) && !ops->write)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	if (type == hwmon_chip) {
>> +		name = (char *)template;
>> +	} else {
>> +		name = devm_kzalloc(dev, strlen(template) + 16, GFP_KERNEL);
>> +		if (!name)
>> +			return ERR_PTR(-ENOMEM);
>> +		scnprintf(name, strlen(template) + 16, template,
>> +			  index + hwmon_attr_base(type));
>> +	}
>> +
>> +	hattr = devm_kzalloc(dev, sizeof(*hattr), GFP_KERNEL);
>> +	if (!hattr)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	hattr->type = type;
>> +	hattr->attr = attr;
>> +	hattr->index = index;
>> +	hattr->ops = ops;
>> +
>> +	dattr = &hattr->dev_attr;
>> +	if (mode & S_IRUGO)
>> +		dattr->show = hwmon_attr_show;
>> +	if (mode & S_IWUGO)
>> +		dattr->store = hwmon_attr_store;
> Technically I think there is no need to worry about setting the store / show
> when they aren't needed.  Maybe, not worth the really small savings though...

Yes, you are right. Not to save some code, but the if statements are really not
necessary and don't add any value.

>> +
>> +	a = &dattr->attr;
>> +	sysfs_attr_init(a);
>> +	a->name = name;
>> +	a->mode = mode;
>> +
>> +	return a;
>> +}
>> +
>> +static const char * const hwmon_chip_attr_templates[] = {
>> +	[hwmon_chip_temp_reset_history] = "temp_reset_history",
>> +	[hwmon_chip_update_interval] = "update_interval",
>> +	[hwmon_chip_alarms] = "alarms",
>> +};
>> +
>> +static const char * const hwmon_temp_attr_templates[] = {
>> +	[hwmon_temp_input] = "temp%d_input",
>> +	[hwmon_temp_type] = "temp%d_type",
>> +	[hwmon_temp_lcrit] = "temp%d_lcrit",
>> +	[hwmon_temp_lcrit_hyst] = "temp%d_lcrit_hyst",
>> +	[hwmon_temp_min] = "temp%d_min",
>> +	[hwmon_temp_min_hyst] = "temp%d_min_hyst",
>> +	[hwmon_temp_max] = "temp%d_max",
>> +	[hwmon_temp_max_hyst] = "temp%d_max_hyst",
>> +	[hwmon_temp_crit] = "temp%d_crit",
>> +	[hwmon_temp_crit_hyst] = "temp%d_crit_hyst",
>> +	[hwmon_temp_emergency] = "temp%d_emergency",
>> +	[hwmon_temp_emergency_hyst] = "temp%d_emergency_hyst",
>> +	[hwmon_temp_alarm] = "temp%d_alarm",
>> +	[hwmon_temp_lcrit_alarm] = "temp%d_lcrit_alarm",
>> +	[hwmon_temp_min_alarm] = "temp%d_min_alarm",
>> +	[hwmon_temp_max_alarm] = "temp%d_max_alarm",
>> +	[hwmon_temp_crit_alarm] = "temp%d_crit_alarm",
>> +	[hwmon_temp_emergency_alarm] = "temp%d_emergency_alarm",
>> +	[hwmon_temp_fault] = "temp%d_fault",
>> +	[hwmon_temp_offset] = "temp%d_offset",
>> +	[hwmon_temp_label] = "temp%d_label",
>> +	[hwmon_temp_lowest] = "temp%d_lowest",
>> +	[hwmon_temp_highest] = "temp%d_highest",
>> +	[hwmon_temp_reset_history] = "temp%d_reset_history",
>> +};
>> +
>> +static const char * const *__templates[] = {
>> +	[hwmon_chip] = hwmon_chip_attr_templates,
>> +	[hwmon_temp] = hwmon_temp_attr_templates,
>> +};
>> +
>> +static const int __templates_size[] = {
>> +	[hwmon_chip] = ARRAY_SIZE(hwmon_chip_attr_templates),
>> +	[hwmon_temp] = ARRAY_SIZE(hwmon_temp_attr_templates),
>> +};
>> +
>> +static int hwmon_num_channel_attrs(const struct hwmon_channel_info *info)
>> +{
>> +	int i, n;
>> +
>> +	for (i = n = 0; info->config[i]; i++)
>> +		n += hweight32(info->config[i]);
>> +
>> +	return n;
>> +}
>> +
>> +static int hwmon_genattrs(struct device *dev,
>> +			  const void *drvdata,
>> +			  struct attribute **attrs,
>> +			  const struct hwmon_ops *ops,
>> +			  const struct hwmon_channel_info *info)
>> +{
>> +	const char * const *templates;
>> +	int template_size;
>> +	int i, aindex = 0;
>> +
>> +	if (info->type >= ARRAY_SIZE(__templates))
>> +		return -EINVAL;
>> +
>> +	templates = __templates[info->type];
>> +	template_size = __templates_size[info->type];
>> +
>> +	for (i = 0; info->config[i]; i++) {
>> +		u32 attr_mask = info->config[i];
>> +		u32 attr;
>> +
>> +		while (attr_mask) {
>> +			struct attribute *a;
>> +
>> +			attr = __ffs(attr_mask);
>> +			attr_mask &= ~BIT(attr);
> loop instead using the for_each_bit_set?  Tiny bit cleaner perhaps...

A bit, maybe, though not much. I changed it, but since for_each_set_bit() requires
a pointer to an unsigned long as argument, I still need attr_mask as temporary
variable (I don't want to use unsigned long for the config bit mask since
its size is not well defined). Hmm ... that also means that switching to u64
in the future will be tricky. I'll need to think about that some more.

>> +			if (attr >= template_size)
>> +				return -EINVAL;
>> +			a = hwmon_genattr(dev, drvdata, info->type, attr, i,
>> +					  templates[attr], ops);
>> +			if (IS_ERR(a)) {
>> +				if (PTR_ERR(a) != -ENOENT)
>> +					return PTR_ERR(a);
>> +				continue;
>> +			}
>> +			attrs[aindex++] = a;
>> +		}
>> +	}
>> +	return aindex;
>> +}
>> +
>> +static struct attribute **
>> +__hwmon_create_attrs(struct device *dev, const void *drvdata,
>> +		     const struct hwmon_chip_info *chip)
>> +{
>> +	int ret, i, aindex = 0, nattrs = 0;
>> +	struct attribute **attrs;
>> +
>> +	for (i = 0; chip->info[i]; i++)
>> +		nattrs += hwmon_num_channel_attrs(chip->info[i]);
>> +
>> +	if (nattrs == 0)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	attrs = devm_kcalloc(dev, nattrs + 1, sizeof(*attrs), GFP_KERNEL);
>> +	if (attrs == NULL)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	for (i = 0; chip->info[i]; i++) {
>> +		ret = hwmon_genattrs(dev, drvdata, &attrs[aindex], chip->ops,
>> +				     chip->info[i]);
>> +		if (ret < 0)
>> +			return ERR_PTR(ret);
>> +		aindex += ret;
>> +	}
>> +
>> +	return attrs;
>> +}
>> +
>> +static struct device *
>> +__hwmon_device_register(struct device *dev, const char *name, void *drvdata,
>> +			const struct hwmon_chip_info *chip,
>> +			const struct attribute_group **groups)
>>   {
>>   	struct hwmon_device *hwdev;
>> -	int err, id;
>> +	struct device *hdev;
>> +	int i, j, err, id;
>>
>>   	/* Do not accept invalid characters in hwmon name attribute */
>>   	if (name && (!strlen(name) || strpbrk(name, "-* \t\n")))
>> @@ -114,28 +392,128 @@ hwmon_device_register_with_groups(struct device *dev, const char *name,
>>   		goto ida_remove;
>>   	}
>>
>> +	hdev = &hwdev->dev;
>> +
>> +	if (chip && chip->ops->is_visible) {
>> +		struct attribute **attrs;
>> +		int ngroups = 2;
>> +
>> +		if (groups)
>> +			for (i = 0; groups[i]; i++)
>> +				ngroups++;
>> +
>> +		hwdev->groups = devm_kcalloc(dev, ngroups, sizeof(*groups),
>> +					     GFP_KERNEL);
>> +		if (hwdev->groups == NULL)
>> +			return ERR_PTR(-ENOMEM);
>> +
>> +		attrs = __hwmon_create_attrs(dev, drvdata, chip);
>> +		if (IS_ERR(attrs)) {
>> +			err = PTR_ERR(attrs);
>> +			goto free_hwmon;
>> +		}
>> +
>> +		hwdev->group.attrs = attrs;
>> +		ngroups = 0;
>> +		hwdev->groups[ngroups++] = &hwdev->group;
>> +
>> +		if (groups) {
>> +			for (i = 0; groups[i]; i++)
>> +				hwdev->groups[ngroups++] = groups[i];
>> +		}
>> +
>> +		hdev->groups = hwdev->groups;
>> +	} else {
>> +		hdev->groups = groups;
>> +	}
>> +
>>   	hwdev->name = name;
>> -	hwdev->dev.class = &hwmon_class;
>> -	hwdev->dev.parent = dev;
>> -	hwdev->dev.groups = groups;
>> -	hwdev->dev.of_node = dev ? dev->of_node : NULL;
>> -	dev_set_drvdata(&hwdev->dev, drvdata);
>> -	dev_set_name(&hwdev->dev, HWMON_ID_FORMAT, id);
>> -	err = device_register(&hwdev->dev);
>> +	hdev->class = &hwmon_class;
>> +	hdev->parent = dev;
>> +	hdev->of_node = dev ? dev->of_node : NULL;
>> +	hwdev->chip = chip;
>> +	dev_set_drvdata(hdev, drvdata);
>> +	dev_set_name(hdev, HWMON_ID_FORMAT, id);
>> +	err = device_register(hdev);
>>   	if (err)
>> -		goto free;
>> +		goto free_hwmon;
>> +
>> +	if (chip && chip->ops->is_visible && chip->ops->read &&
>> +	    chip->info[0]->type == hwmon_chip &&
>> +	    (chip->info[0]->config[0] & HWMON_C_REGISTER_TZ)) {
>> +		const struct hwmon_channel_info **info = chip->info;
>> +
>> +		for (i = 1; info[i]; i++) {
>> +			if (info[i]->type != hwmon_temp)
>> +				continue;
>> +
>> +			for (j = 0; info[i]->config[j]; j++) {
>> +				if (!chip->ops->is_visible(drvdata, hwmon_temp,
>> +							   hwmon_temp_input, j))
>> +					continue;
>> +				if (info[i]->config[j] & HWMON_T_INPUT)
>> +					hwmon_thermal_add_sensor(dev, hwdev, j);
>> +			}
>> +		}
>> +	}
>>
>> -	return &hwdev->dev;
>> +	return hdev;
>>
>> -free:
>> +free_hwmon:
>>   	kfree(hwdev);
>>   ida_remove:
>>   	ida_simple_remove(&hwmon_ida, id);
>>   	return ERR_PTR(err);
>>   }
>> +
>> +/**
>> + * hwmon_device_register_with_groups - register w/ hwmon
>> + * @dev: the parent device
>> + * @name: hwmon name attribute
>> + * @drvdata: driver data to attach to created device
>> + * @groups: List of attribute groups to create
>> + *
>> + * hwmon_device_unregister() must be called when the device is no
>> + * longer needed.
>> + *
>> + * Returns the pointer to the new device.
>> + */
>> +struct device *
>> +hwmon_device_register_with_groups(struct device *dev, const char *name,
>> +				  void *drvdata,
>> +				  const struct attribute_group **groups)
>> +{
>> +	return __hwmon_device_register(dev, name, drvdata, NULL, groups);
>> +}
>>   EXPORT_SYMBOL_GPL(hwmon_device_register_with_groups);
>>
>>   /**
>> + * hwmon_device_register_with_info - register w/ hwmon
>> + * @dev: the parent device
>> + * @name: hwmon name attribute
>> + * @drvdata: driver data to attach to created device
>> + * @info: Pointer to hwmon chip information
>> + * @groups - pointer to list of driver specific attribute groups
>> + *
>> + * hwmon_device_unregister() must be called when the device is no
>> + * longer needed.
>> + *
>> + * Returns the pointer to the new device.
>> + */
>> +struct device *
>> +hwmon_device_register_with_info(struct device *dev, const char *name,
>> +				  void *drvdata,
>> +				  const struct hwmon_chip_info *chip,
>> +				  const struct attribute_group **groups)
>> +{
>> +	if (chip && (!chip->ops || !chip->info))
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	return __hwmon_device_register(dev, name, drvdata, chip, groups);
>> +}
>> +EXPORT_SYMBOL_GPL(hwmon_device_register_with_info);
>> +
>> +/**
>>    * hwmon_device_register - register w/ hwmon
>>    * @dev: the device to register
>>    *
>> @@ -213,6 +591,47 @@ error:
>>   }
>>   EXPORT_SYMBOL_GPL(devm_hwmon_device_register_with_groups);
>>
>> +/**
>> + * devm_hwmon_device_register_with_info - register w/ hwmon
>> + * @dev: the parent device
>> + * @name: hwmon name attribute
>> + * @drvdata: driver data to attach to created device
>> + * @info: Pointer to hwmon chip information
>> + * @groups - pointer to list of driver specific attribute groups
>> + *
>> + * Returns the pointer to the new device. The new device is automatically
>> + * unregistered with the parent device.
>> + */
>> +struct device *
>> +devm_hwmon_device_register_with_info(struct device *dev, const char *name,
>> +				     void *drvdata,
>> +				     const struct hwmon_chip_info *chip,
>> +				     const struct attribute_group **groups)
>> +{
>> +	struct device **ptr, *hwdev;
>> +
>> +	if (!dev)
>> +		return ERR_PTR(-EINVAL);
>> +
>> +	ptr = devres_alloc(devm_hwmon_release, sizeof(*ptr), GFP_KERNEL);
>> +	if (!ptr)
>> +		return ERR_PTR(-ENOMEM);
>> +
>> +	hwdev = hwmon_device_register_with_info(dev, name, drvdata, chip,
>> +						groups);
>> +	if (IS_ERR(hwdev))
>> +		goto error;
>> +
>> +	*ptr = hwdev;
>> +	devres_add(dev, ptr);
> Perhaps a blank line here? (really tiny improvement in readability?
>> +	return hwdev;
>> +
>> +error:
>> +	devres_free(ptr);
>> +	return hwdev;
>> +}
>> +EXPORT_SYMBOL_GPL(devm_hwmon_device_register_with_info);
>> +
>>   static int devm_hwmon_match(struct device *dev, void *res, void *data)
>>   {
>>   	struct device **hwdev = res;
>> diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
>> index 09354f6c1d63..99250ad092fd 100644
>> --- a/include/linux/hwmon.h
>> +++ b/include/linux/hwmon.h
>> @@ -14,9 +14,121 @@
>>   #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.
>> + *		Optional.
>> + * @read:       Read callback. Optional.
> I'd like to see a little more expansion in this comment on the form of the
> callbacks.  What are the parameters etc?  I'd expect to look here first
> to find that out rather than diving into docs.

Done.

>> + * @write:	Write callback. Optional.
>> + */
>> +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);
>> +};
>> +
>> +/**
>> + * 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;
> Hmm. Be very careful about running out of space. I did much the same
> in IIO as you know and am somewhat regretting it now a using a bitmap is
> lovely and efficient, but really annoying once you run out of bits
> if you've used a fixed (short) length..
>
> Using a bitmap as defined in bitmap.h doesn't work as there is no elegant
> way of statically defining them beyond the first long.  I really wish
> there was a way of doing this but can't figure out how..
>
Me not either, which is why I did not use it.

> Maybe just go for a u64 from the start (though that then complicates the
> use of some of the bitops stuff) I suspect we'll be jumping to
> that in IIO fairly soon and it'd be a lot less painful to start there
> perhaps...
>
My solution trying to avoid that was to use separate number spaces
for the different sensor types. If/when we hit the limit (temperatures
are getting close), we would have two options: Define a new sensor type
to handle the overflow, or switch to u64. Ultimately I decided to stick
with u32 for now because u64 seemed overkill. On the other side, I made
that decision when the read/write/is_visible API to the drivers included
the bit mask, which is no longer the case. Maybe I'll try with u64 to see
its impact on code size.

>
>> +};
>> +
>> +/**
>> + * Chip configuration
>> + * @ops:	Pointer to hwmon operations.
>> + * @info:	Null-terminated list of channel information.
> Drop the bonus blank line.
>
> We tossed up in IIO for a long time on whether to use a null terminated list
> of our equivalent info elements, or an explict count.  Ended up with count
> as it often allows sharing of the big array of channel info structures
> between different parts where one part adds more hardware over the other..
>
> I'm not saying that the gain by doing that was all that signficant, but
> I thought I'd mention the trade offs.

I went through the same thinking process. At the end, I decided to go with
the terminated list since passing it around seemed to be simpler.
The core has to walk through the list anyway, and the hwmon code does not
require big data structures to describe the channels.

> Here I think you have made the right decision.

Thanks for the feedback, and thanks a lot for your time!

Guenter

Re: [PATCH 0/5] hwmon: New hwmon registration API

[Jonathan Cameron]

On 11/07/16 01:56, Guenter Roeck wrote:
> Hi Jonathan,
> 
> On 07/10/2016 09:00 AM, Jonathan Cameron wrote:
>> On 26/06/16 04:26, Guenter Roeck wrote:
>>> 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 introduces the API as well as support
>>> for temperature sensors. Subsequent patches introduce support for
>>> voltage, current, power, energy, humidity, and fan speed sensors.
>>>
>>> The series was tested by converting several drivers (lm75, lm90, tmp102,
>>> tmp421, ltc4245) to the new API. Testing was done with with real chips
>>> as well as with the hwmon driver module test code available at
>>> https://github.com/groeck/module-tests.
>> Some cool stuff hiding in there :)
>>
>> I've only reviewed 1 and 7 and the intermediate ones are really either
>> correct or they aren't and they look fine to me.
>>
> Thanks a lot for your feedback - it is reassuring that it looks sane to you.
> 
>>
>> So what's next? (beyond presumably a lot of driver conversions).
>>
> Next steps will be to address your comments, re-test, submit a new series,
> add to -next after v4.8-rc1 is out, submit the conversions I have done
> and add to -next. Then, obviously, only accept new drivers using the
> new API.
> 
> Not sure if there is anything else we can or want to do do at this time.
> Do you have anything in mind ?
> 
Was wondering about the bridge to IIO (reverse of iio to hwmon bridge)
that you mentioned - for that you'd probably need some in kernel interfaces
for all this stuff.

Anyhow, stuff for the future (perhaps distant)

Jonathan
> Thanks,
> Guenter
> 

Re: [PATCH 0/5] hwmon: New hwmon registration API

[Jonathan Cameron]

On 11/07/16 01:56, Guenter Roeck wrote:
> Hi Jonathan,
> 
> On 07/10/2016 09:00 AM, Jonathan Cameron wrote:
>> On 26/06/16 04:26, Guenter Roeck wrote:
>>> 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 introduces the API as well as support
>>> for temperature sensors. Subsequent patches introduce support for
>>> voltage, current, power, energy, humidity, and fan speed sensors.
>>>
>>> The series was tested by converting several drivers (lm75, lm90, tmp102,
>>> tmp421, ltc4245) to the new API. Testing was done with with real chips
>>> as well as with the hwmon driver module test code available at
>>> https://github.com/groeck/module-tests.
>> Some cool stuff hiding in there :)
>>
>> I've only reviewed 1 and 7 and the intermediate ones are really either
>> correct or they aren't and they look fine to me.
>>
> Thanks a lot for your feedback - it is reassuring that it looks sane to you.
> 
>>
>> So what's next? (beyond presumably a lot of driver conversions).
>>
> Next steps will be to address your comments, re-test, submit a new series,
> add to -next after v4.8-rc1 is out, submit the conversions I have done
> and add to -next. Then, obviously, only accept new drivers using the
> new API.
> 
> Not sure if there is anything else we can or want to do do at this time.
> Do you have anything in mind ?
> 
Was wondering about the bridge to IIO (reverse of iio to hwmon bridge)
that you mentioned - for that you'd probably need some in kernel interfaces
for all this stuff.

Anyhow, stuff for the future (perhaps distant)

Jonathan
> Thanks,
> Guenter
> 

Re: [PATCH 0/5] hwmon: New hwmon registration API

[Guenter Roeck]

On Wed, Jul 20, 2016 at 04:11:04PM +0100, Jonathan Cameron wrote:
> On 11/07/16 01:56, Guenter Roeck wrote:
> > Hi Jonathan,
> > 
> > On 07/10/2016 09:00 AM, Jonathan Cameron wrote:
> >> On 26/06/16 04:26, Guenter Roeck wrote:
> >>> 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 introduces the API as well as support
> >>> for temperature sensors. Subsequent patches introduce support for
> >>> voltage, current, power, energy, humidity, and fan speed sensors.
> >>>
> >>> The series was tested by converting several drivers (lm75, lm90, tmp102,
> >>> tmp421, ltc4245) to the new API. Testing was done with with real chips
> >>> as well as with the hwmon driver module test code available at
> >>> https://github.com/groeck/module-tests.
> >> Some cool stuff hiding in there :)
> >>
> >> I've only reviewed 1 and 7 and the intermediate ones are really either
> >> correct or they aren't and they look fine to me.
> >>
> > Thanks a lot for your feedback - it is reassuring that it looks sane to you.
> > 
> >>
> >> So what's next? (beyond presumably a lot of driver conversions).
> >>
> > Next steps will be to address your comments, re-test, submit a new series,
> > add to -next after v4.8-rc1 is out, submit the conversions I have done
> > and add to -next. Then, obviously, only accept new drivers using the
> > new API.
> > 
> > Not sure if there is anything else we can or want to do do at this time.
> > Do you have anything in mind ?
> > 
> Was wondering about the bridge to IIO (reverse of iio to hwmon bridge)
> that you mentioned - for that you'd probably need some in kernel interfaces
> for all this stuff.
> 

Depends; maybe it would be sufficient to call devm_iio_device_register() with
a minimum set of channel information. Looks like all we would need is .read_raw
and .write_raw callbacks in struct iio_info, a channel description for each
channel, and the number of channels. Implementing this would not be difficult.
Only question would be if it would be sufficient for most or at least many
use cases.

Thanks,
Guenter