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Subject[PATCH 1/2] hwmon: (core) Add hwmon_mode structure and mode sysfs node
Date
There are a few hwmon sensors support different operating modes,
for example, one-shot and continuous modes. So it's probably not
a bad idea to abstract a mode sysfs node as a common feature in
the hwmon core.

Right beside the hwmon device name, this patch adds a new sysfs
attribute named "mode" and "available_modes" for user to check
and configure the operating mode. For hwmon device drivers that
implemented the _with_info API, the change also adds an optional
hwmon_mode structure in hwmon_chip_info structure so that those
drivers can pass mode related information.

Signed-off-by: Nicolin Chen <nicoleotsuka@gmail.com>
---
Documentation/hwmon/sysfs-interface | 15 +++++
drivers/hwmon/hwmon.c | 87 ++++++++++++++++++++++++++---
include/linux/hwmon.h | 24 ++++++++
3 files changed, 119 insertions(+), 7 deletions(-)

diff --git a/Documentation/hwmon/sysfs-interface b/Documentation/hwmon/sysfs-interface
index 2b9e1005d88b..48d6ca6b9bd4 100644
--- a/Documentation/hwmon/sysfs-interface
+++ b/Documentation/hwmon/sysfs-interface
@@ -92,6 +92,21 @@ name The chip name.
I2C devices get this attribute created automatically.
RO

+available_modes The available operating modes of the chip.
+ This should be short, lowercase string, not containing
+ whitespace, or the wildcard character '*'.
+ This attribute shows all the available of the operating modes,
+ for example, "power-down" "one-shot" and "continuous".
+ RO
+
+mode The current operating mode of the chip.
+ This should be short, lowercase string, not containing
+ whitespace, or the wildcard character '*'.
+ This attribute shows the current operating mode of the chip.
+ Writing a valid string from the list of available_modes will
+ configure the chip to the corresponding operating mode.
+ RW
+
update_interval The interval at which the chip will update readings.
Unit: millisecond
RW
diff --git a/drivers/hwmon/hwmon.c b/drivers/hwmon/hwmon.c
index 975c95169884..5a33b616284b 100644
--- a/drivers/hwmon/hwmon.c
+++ b/drivers/hwmon/hwmon.c
@@ -72,25 +72,88 @@ name_show(struct device *dev, struct device_attribute *attr, char *buf)
}
static DEVICE_ATTR_RO(name);

+static ssize_t available_modes_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct hwmon_device *hwdev = to_hwmon_device(dev);
+ const struct hwmon_chip_info *chip = hwdev->chip;
+ const struct hwmon_mode *mode = chip->mode;
+ int i;
+
+ for (i = 0; i < mode->list_size; i++)
+ snprintf(buf, PAGE_SIZE, "%s%s ", buf, mode->names[i]);
+
+ return snprintf(buf, PAGE_SIZE, "%s\n", buf);
+}
+static DEVICE_ATTR_RO(available_modes);
+
+static ssize_t mode_show(struct device *dev,
+ struct device_attribute *attr, char *buf)
+{
+ struct hwmon_device *hwdev = to_hwmon_device(dev);
+ const struct hwmon_chip_info *chip = hwdev->chip;
+ const struct hwmon_mode *mode = chip->mode;
+ unsigned int index;
+ int ret;
+
+ ret = mode->get_index(dev, &index);
+ if (ret)
+ return ret;
+
+ return snprintf(buf, PAGE_SIZE, "%s\n", mode->names[index]);
+}
+
+static ssize_t mode_store(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
+{
+ struct hwmon_device *hwdev = to_hwmon_device(dev);
+ const struct hwmon_chip_info *chip = hwdev->chip;
+ const struct hwmon_mode *mode = chip->mode;
+ const char **names = mode->names;
+ unsigned int index;
+ int ret;
+
+ /* Get the corresponding mode index */
+ for (index = 0; index < mode->list_size; index++) {
+ if (!strncmp(buf, names[index], strlen(names[index])))
+ break;
+ }
+
+ if (index >= mode->list_size)
+ return -EINVAL;
+
+ ret = mode->set_index(dev, index);
+ if (ret)
+ return ret;
+
+ return count;
+}
+static DEVICE_ATTR_RW(mode);
+
static struct attribute *hwmon_dev_attrs[] = {
- &dev_attr_name.attr,
+ &dev_attr_name.attr, /* index = 0 */
+ &dev_attr_available_modes.attr, /* index = 1 */
+ &dev_attr_mode.attr, /* index = 2 */
NULL
};

-static umode_t hwmon_dev_name_is_visible(struct kobject *kobj,
- struct attribute *attr, int n)
+static umode_t hwmon_dev_is_visible(struct kobject *kobj,
+ struct attribute *attr, int n)
{
struct device *dev = container_of(kobj, struct device, kobj);
+ struct hwmon_device *hwdev = to_hwmon_device(dev);

- if (to_hwmon_device(dev)->name == NULL)
- return 0;
+ if (n == 0 && hwdev->name)
+ return attr->mode;
+ else if (n <= 2 && hwdev->chip->mode)
+ return attr->mode;

- return attr->mode;
+ return 0;
}

static const struct attribute_group hwmon_dev_attr_group = {
.attrs = hwmon_dev_attrs,
- .is_visible = hwmon_dev_name_is_visible,
+ .is_visible = hwmon_dev_is_visible,
};

static const struct attribute_group *hwmon_dev_attr_groups[] = {
@@ -591,6 +654,16 @@ __hwmon_device_register(struct device *dev, const char *name, void *drvdata,
struct attribute **attrs;
int ngroups = 2; /* terminating NULL plus &hwdev->groups */

+ /* Validate optional hwmon_mode */
+ if (chip->mode) {
+ /* Check mandatory properties */
+ if (!chip->mode->names || !chip->mode->list_size ||
+ !chip->mode->get_index || !chip->mode->set_index) {
+ err = -EINVAL;
+ goto free_hwmon;
+ }
+ }
+
if (groups)
for (i = 0; groups[i]; i++)
ngroups++;
diff --git a/include/linux/hwmon.h b/include/linux/hwmon.h
index 99e0c1b0b5fb..06c1940ca98b 100644
--- a/include/linux/hwmon.h
+++ b/include/linux/hwmon.h
@@ -365,14 +365,38 @@ struct hwmon_channel_info {
const u32 *config;
};

+/**
+ * Chip operating mode information
+ * @names: A list of available operating mode names.
+ * @list_size: The total number of available operating mode names.
+ * @get_index: Callback to get current operating mode index. Mandatory.
+ * Parameters are:
+ * @dev: Pointer to hardware monitoring device
+ * @index: Pointer to returned mode index
+ * The function returns 0 on success or a negative error number.
+ * @set_index: Callback to set operating mode using the index. Mandatory.
+ * Parameters are:
+ * @dev: Pointer to hardware monitoring device
+ * @index: Mode index in the mode list
+ * The function returns 0 on success or a negative error number.
+ */
+struct hwmon_mode {
+ const char **names;
+ unsigned int list_size;
+ int (*get_index)(struct device *dev, unsigned int *index);
+ int (*set_index)(struct device *dev, unsigned int index);
+};
+
/**
* Chip configuration
* @ops: Pointer to hwmon operations.
* @info: Null-terminated list of channel information.
+ * @mode: Pointer to hwmon operating mode (optional).
*/
struct hwmon_chip_info {
const struct hwmon_ops *ops;
const struct hwmon_channel_info **info;
+ const struct hwmon_mode *mode;
};

/* hwmon_device_register() is deprecated */
--
2.17.1
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