hwmon: (core) New hwmon registration API

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

To be able to reduce driver complexity, move sensor attribute handling
and thermal zone registration into hwmon core. By using the new API,
driver code and data size is typically reduced by 20-70%, depending
on driver complexity and the number of sysfs attributes supported.

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

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

1 files changed, 458 insertions, 27 deletions

diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index 649a68d119b4..3e4cc442a089 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -12,6 +12,7 @@
 
 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 
+#include <linux/bitops.h>
 #include <linux/device.h>
 #include <linux/err.h>
 #include <linux/gfp.h>
@@ -21,6 +22,7 @@
 #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"
@@ -28,9 +30,35 @@
 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)
 {
@@ -78,25 +106,286 @@ 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 */
+
+#if IS_REACHABLE(CONFIG_THERMAL) && defined(CONFIG_THERMAL_OF)
+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;
+}
+#else
+static int hwmon_thermal_add_sensor(struct device *dev,
+				    struct hwmon_device *hwdev, int index)
+{
+	return 0;
+}
+#endif /* IS_REACHABLE(CONFIG_THERMAL) && defined(CONFIG_THERMAL_OF) */
+
+/* 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;
+
+	/* The attribute is invisible if there is no template string */
+	if (!template)
+		return ERR_PTR(-ENOENT);
+
+	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;
+	dattr->show = hwmon_attr_show;
+	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)
+		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")))
@@ -112,28 +401,128 @@ 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)
+			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
  *
@@ -211,6 +600,48 @@ 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;