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rtc: isl12022: add support for temperature sensor

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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: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/r/20221104110225.2219761-1-linux@rasmusvillemoes.dk
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Rasmus Villemoes 2022-11-04 12:02:25 +01:00 committed by Alexandre Belloni
parent f8513363b0
commit 8d816c1eaa
1 changed files with 94 additions and 0 deletions
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94
drivers/rtc/rtc-isl12022.c
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@ -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);