hwmon: (lm73) Add 'update_interval' attribute (8c14d126) · Commits · e / devices / android_kernel_oneplus_sm7250

Documentation/hwmon/lm73

0 → 100644

+79 −0

Original line number	Diff line number	Diff line
		Kernel driver lm73
		==================

		Supported chips:
		* Texas Instruments LM73
		Prefix: 'lm73'
		Addresses scanned: I2C 0x48, 0x49, 0x4a, 0x4c, 0x4d, and 0x4e
		Datasheet: Publicly available at the Texas Instruments website
		http://www.ti.com/product/lm73

		Author: Guillaume Ligneul <guillaume.ligneul@gmail.com>
		Documentation: Chris Verges <kg4ysn@gmail.com>


		Description
		-----------

		The LM73 is a digital temperature sensor. All temperature values are
		given in degrees Celsius.

		Measurement Resolution Support
		------------------------------

		The LM73 supports four resolutions, defined in terms of degrees C per
		LSB: 0.25, 0.125, 0.0625, and 0.3125. Changing the resolution mode
		affects the conversion time of the LM73's analog-to-digital converter.
		From userspace, the desired resolution can be specified as a function of
		conversion time via the 'update_interval' sysfs attribute for the
		device. This attribute will normalize ranges of input values to the
		maximum times defined for the resolution in the datasheet.

		Resolution Conv. Time Input Range
		(C/LSB) (msec) (msec)
		--------------------------------------
		0.25 14 0..14
		0.125 28 15..28
		0.0625 56 29..56
		0.03125 112 57..infinity
		--------------------------------------

		The following examples show how the 'update_interval' attribute can be
		used to change the conversion time:

		$ echo 0 > update_interval
		$ cat update_interval
		14
		$ cat temp1_input
		24250

		$ echo 22 > update_interval
		$ cat update_interval
		28
		$ cat temp1_input
		24125

		$ echo 56 > update_interval
		$ cat update_interval
		56
		$ cat temp1_input
		24062

		$ echo 85 > update_interval
		$ cat update_interval
		112
		$ cat temp1_input
		24031

		As shown here, the lm73 driver automatically adjusts any user input for
		'update_interval' via a step function. Reading back the
		'update_interval' value after a write operation will confirm the
		conversion time actively in use.

		Mathematically, the resolution can be derived from the conversion time
		via the following function:

		g(x) = 0.250 * [log(x/14) / log(2)]

		where 'x' is the output from 'update_interval' and 'g(x)' is the
		resolution in degrees C per LSB.

drivers/hwmon/lm73.c

+86 −11

Original line number	Diff line number	Diff line
		@@ -39,8 +39,24 @@ static const unsigned short normal_i2c[] = { 0x48, 0x49, 0x4a, 0x4c,
		#define LM73_TEMP_MIN (-256000 / 250)
		#define LM73_TEMP_MAX (255750 / 250)

		/-----------------------------------------------------------------------/
		#define LM73_CTRL_RES_SHIFT 5
		#define LM73_CTRL_RES_MASK (BIT(5) \| BIT(6))
		#define LM73_CTRL_TO_MASK BIT(7)

		static const unsigned short lm73_convrates[] = {
		14, /* 11-bits (0.25000 C/LSB): RES1 Bit = 0, RES0 Bit = 0 */
		28, /* 12-bits (0.12500 C/LSB): RES1 Bit = 0, RES0 Bit = 1 */
		56, /* 13-bits (0.06250 C/LSB): RES1 Bit = 1, RES0 Bit = 0 */
		112, /* 14-bits (0.03125 C/LSB): RES1 Bit = 1, RES0 Bit = 1 */
		};

		struct lm73_data {
		struct device *hwmon_dev;
		struct mutex lock;
		u8 ctrl; /* control register value */
		};

		/-----------------------------------------------------------------------/

		static ssize_t set_temp(struct device dev, struct device_attribute da,
		const char *buf, size_t count)
		@@ -78,6 +94,51 @@ static ssize_t show_temp(struct device dev, struct device_attribute da,
		return scnprintf(buf, PAGE_SIZE, "%d\n", temp);
		}

		static ssize_t set_convrate(struct device dev, struct device_attribute da,
		const char *buf, size_t count)
		{
		struct i2c_client *client = to_i2c_client(dev);
		struct lm73_data *data = i2c_get_clientdata(client);
		unsigned long convrate;
		s32 err;
		int res = 0;

		err = kstrtoul(buf, 10, &convrate);
		if (err < 0)
		return err;

		/*
		* Convert the desired conversion rate into register bits.
		* res is already initialized, and everything past the second-to-last
		* value in the array is treated as belonging to the last value
		* in the array.
		*/
		while (res < (ARRAY_SIZE(lm73_convrates) - 1) &&
		convrate > lm73_convrates[res])
		res++;

		mutex_lock(&data->lock);
		data->ctrl &= LM73_CTRL_TO_MASK;
		data->ctrl \|= res << LM73_CTRL_RES_SHIFT;
		err = i2c_smbus_write_byte_data(client, LM73_REG_CTRL, data->ctrl);
		mutex_unlock(&data->lock);

		if (err < 0)
		return err;

		return count;
		}

		static ssize_t show_convrate(struct device dev, struct device_attribute da,
		char *buf)
		{
		struct i2c_client *client = to_i2c_client(dev);
		struct lm73_data *data = i2c_get_clientdata(client);
		int res;

		res = (data->ctrl & LM73_CTRL_RES_MASK) >> LM73_CTRL_RES_SHIFT;
		return scnprintf(buf, PAGE_SIZE, "%hu\n", lm73_convrates[res]);
		}

		/-----------------------------------------------------------------------/

		@@ -89,13 +150,14 @@ static SENSOR_DEVICE_ATTR(temp1_min, S_IWUSR \| S_IRUGO,
		show_temp, set_temp, LM73_REG_MIN);
		static SENSOR_DEVICE_ATTR(temp1_input, S_IRUGO,
		show_temp, NULL, LM73_REG_INPUT);

		static SENSOR_DEVICE_ATTR(update_interval, S_IWUSR \| S_IRUGO,
		show_convrate, set_convrate, 0);

		static struct attribute *lm73_attributes[] = {
		&sensor_dev_attr_temp1_input.dev_attr.attr,
		&sensor_dev_attr_temp1_max.dev_attr.attr,
		&sensor_dev_attr_temp1_min.dev_attr.attr,

		&sensor_dev_attr_update_interval.dev_attr.attr,
		NULL
		};

		@@ -110,23 +172,36 @@ static const struct attribute_group lm73_group = {
		static int
		lm73_probe(struct i2c_client client, const struct i2c_device_id id)
		{
		struct device *hwmon_dev;
		int status;
		struct lm73_data *data;
		int ctrl;

		data = devm_kzalloc(&client->dev, sizeof(struct lm73_data),
		GFP_KERNEL);
		if (!data)
		return -ENOMEM;

		i2c_set_clientdata(client, data);
		mutex_init(&data->lock);

		ctrl = i2c_smbus_read_byte_data(client, LM73_REG_CTRL);
		if (ctrl < 0)
		return ctrl;
		data->ctrl = ctrl;

		/* Register sysfs hooks */
		status = sysfs_create_group(&client->dev.kobj, &lm73_group);
		if (status)
		return status;

		hwmon_dev = hwmon_device_register(&client->dev);
		if (IS_ERR(hwmon_dev)) {
		status = PTR_ERR(hwmon_dev);
		data->hwmon_dev = hwmon_device_register(&client->dev);
		if (IS_ERR(data->hwmon_dev)) {
		status = PTR_ERR(data->hwmon_dev);
		goto exit_remove;
		}
		i2c_set_clientdata(client, hwmon_dev);

		dev_info(&client->dev, "%s: sensor '%s'\n",
		dev_name(hwmon_dev), client->name);
		dev_name(data->hwmon_dev), client->name);

		return 0;

		@@ -137,9 +212,9 @@ lm73_probe(struct i2c_client client, const struct i2c_device_id id)

		static int lm73_remove(struct i2c_client *client)
		{
		struct device *hwmon_dev = i2c_get_clientdata(client);
		struct lm73_data *data = i2c_get_clientdata(client);

		hwmon_device_unregister(hwmon_dev);
		hwmon_device_unregister(data->hwmon_dev);
		sysfs_remove_group(&client->dev.kobj, &lm73_group);
		return 0;
		}