From 8d816c1eaa752546fa3221f5027af0a667ff0c8f Mon Sep 17 00:00:00 2001 From: Rasmus Villemoes Date: Fri, 4 Nov 2022 12:02:25 +0100 Subject: 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: Guenter Roeck Signed-off-by: Rasmus Villemoes Link: https://lore.kernel.org/r/20221104110225.2219761-1-linux@rasmusvillemoes.dk Signed-off-by: Alexandre Belloni --- drivers/rtc/rtc-isl12022.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 94 insertions(+) (limited to 'drivers/rtc') diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c index ca677c4265e6..a3b0de3393f5 100644 --- a/drivers/rtc/rtc-isl12022.c +++ b/drivers/rtc/rtc-isl12022.c @@ -17,6 +17,7 @@ #include #include #include +#include /* 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); -- cgit v1.2.3