Commit 8d816c1e authored by Rasmus Villemoes's avatar Rasmus Villemoes Committed by Alexandre Belloni
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rtc: isl12022: add support for temperature sensor 



The isl12022 has built-in temperature compensation effective over the
range -40C to +85C. It exposes the average of the last two temperature
measurements as a 10-bit value in half-Kelvins. Make this available
via the hwmon framework.

Reviewed-by: default avatarGuenter Roeck <linux@roeck-us.net>
Signed-off-by: default avatarRasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/r/20221104110225.2219761-1-linux@rasmusvillemoes.dk


Signed-off-by: default avatarAlexandre Belloni <alexandre.belloni@bootlin.com>
parent f8513363

drivers/rtc/rtc-isl12022.c

+94 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ 
#include <linux/of.h>

#include <linux/of_device.h>

#include <linux/regmap.h>

#include <linux/hwmon.h>



/* ISL register offsets */

#define ISL12022_REG_SC		0x00
@@ -30,6 +31,9 @@ 
#define ISL12022_REG_SR		0x07

#define ISL12022_REG_INT	0x08



#define ISL12022_REG_BETA	0x0d

#define ISL12022_REG_TEMP_L	0x28



/* ISL register bits */

#define ISL12022_HR_MIL		(1 << 7)	/* military or 24 hour time */
@@ -38,6 +42,7 @@ 


#define ISL12022_INT_WRTC	(1 << 6)



#define ISL12022_BETA_TSE	(1 << 7)



static struct i2c_driver isl12022_driver;
@@ -46,6 +51,93 @@ struct isl12022 { 
	struct regmap *regmap;

};



static umode_t isl12022_hwmon_is_visible(const void *data,

					 enum hwmon_sensor_types type,

					 u32 attr, int channel)

{

	if (type == hwmon_temp && attr == hwmon_temp_input)

		return 0444;



	return 0;

}



/*

 * A user-initiated temperature conversion is not started by this function,

 * so the temperature is updated once every ~60 seconds.

 */

static int isl12022_hwmon_read_temp(struct device *dev, long *mC)

{

	struct isl12022 *isl12022 = dev_get_drvdata(dev);

	struct regmap *regmap = isl12022->regmap;

	u8 temp_buf[2];

	int temp, ret;



	ret = regmap_bulk_read(regmap, ISL12022_REG_TEMP_L,

			       temp_buf, sizeof(temp_buf));

	if (ret)

		return ret;

	/*

	 * Temperature is represented as a 10-bit number, unit half-Kelvins.

	 */

	temp = (temp_buf[1] << 8) | temp_buf[0];

	temp *= 500;

	temp -= 273000;



	*mC = temp;



	return 0;

}



static int isl12022_hwmon_read(struct device *dev,

			       enum hwmon_sensor_types type,

			       u32 attr, int channel, long *val)

{

	if (type == hwmon_temp && attr == hwmon_temp_input)

		return isl12022_hwmon_read_temp(dev, val);



	return -EOPNOTSUPP;

}



static const struct hwmon_channel_info *isl12022_hwmon_info[] = {

	HWMON_CHANNEL_INFO(temp, HWMON_T_INPUT),

	NULL

};



static const struct hwmon_ops isl12022_hwmon_ops = {

	.is_visible = isl12022_hwmon_is_visible,

	.read = isl12022_hwmon_read,

};



static const struct hwmon_chip_info isl12022_hwmon_chip_info = {

	.ops = &isl12022_hwmon_ops,

	.info = isl12022_hwmon_info,

};



static void isl12022_hwmon_register(struct device *dev)

{

	struct isl12022 *isl12022;

	struct device *hwmon;

	int ret;



	if (!IS_REACHABLE(CONFIG_HWMON))

		return;



	isl12022 = dev_get_drvdata(dev);



	ret = regmap_update_bits(isl12022->regmap, ISL12022_REG_BETA,

				 ISL12022_BETA_TSE, ISL12022_BETA_TSE);

	if (ret) {

		dev_warn(dev, "unable to enable temperature sensor\n");

		return;

	}



	hwmon = devm_hwmon_device_register_with_info(dev, "isl12022", isl12022,

						     &isl12022_hwmon_chip_info,

						     NULL);

	if (IS_ERR(hwmon))

		dev_warn(dev, "unable to register hwmon device: %pe\n", hwmon);

}



/*

 * In the routines that deal directly with the isl12022 hardware, we use

 * rtc_time -- month 0-11, hour 0-23, yr = calendar year-epoch.
@@ -160,6 +252,8 @@ static int isl12022_probe(struct i2c_client *client) 
		return PTR_ERR(isl12022->regmap);

	}



	isl12022_hwmon_register(&client->dev);



	isl12022->rtc = devm_rtc_allocate_device(&client->dev);

	if (IS_ERR(isl12022->rtc))

		return PTR_ERR(isl12022->rtc);