[PATCH v2 9/9] rtc: isl12022: add support for temperature sensor

Rasmus Villemoes
2022-09-21T11:47:37Z

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
drivers/rtc/rtc-isl12022.c | 104 +++++++++++++++++++++++++++++++++++++
1 file changed, 104 insertions(+)

diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c
index ca677c4265e6..f3efe61c81e5 100644
--- a/drivers/rtc/rtc-isl12022.c
+++ b/drivers/rtc/rtc-isl12022.c
@@ -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 +51,103 @@ 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_chip && attr == hwmon_chip_update_interval)
+ return 0444;
+
+ 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_chip && attr == hwmon_chip_update_interval) {
+ *val = 60000;
+ return 0;
+ }
+
+ 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(chip, HWMON_C_UPDATE_INTERVAL),
+ 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 +262,8 @@ 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);
--
2.37.2