[PATCH 6/6] rtc: isl12022: add support for temperature sensor

Rasmus Villemoes
2022-08-30T10:05:35Z

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
---
drivers/rtc/rtc-isl12022.c | 81 ++++++++++++++++++++++++++++++++++++++
1 file changed, 81 insertions(+)

diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c
index b295ec92ee17..1bd72f436318 100644
--- a/drivers/rtc/rtc-isl12022.c
+++ b/drivers/rtc/rtc-isl12022.c
@@ -17,6 +17,8 @@
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/regmap.h>
+#include <linux/hwmon.h>
+#include <linux/hwmon-sysfs.h>

/* ISL register offsets */
#define ISL12022_REG_SC 0x00
@@ -30,6 +32,9 @@
#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 +43,7 @@

#define ISL12022_INT_WRTC (1 << 6)

+#define ISL12022_BETA_TSE (1 << 7)

static struct i2c_driver isl12022_driver;

@@ -48,6 +54,79 @@ struct isl12022 {
bool write_enabled; /* true if write enable is set */
};

+/*
+ * 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, s32 *mC)
+{
+ struct isl12022 *isl12022 = dev_get_drvdata(dev);
+ struct regmap *regmap = isl12022->regmap;
+ u8 temp_buf[2];
+ s32 temp;
+ int 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 ssize_t
+isl12022_hwmon_show_temp(struct device *dev, struct device_attribute *attr, char *buf)
+{
+ int ret;
+ s32 temp;
+
+ ret = isl12022_hwmon_read_temp(dev, &temp);
+ if (ret)
+ return ret;
+
+ return sprintf(buf, "%d\n", temp);
+}
+static SENSOR_DEVICE_ATTR(temp1_input, 0444, isl12022_hwmon_show_temp,
+ NULL, 0);
+
+static struct attribute *isl12022_hwmon_attrs[] = {
+ &sensor_dev_attr_temp1_input.dev_attr.attr,
+ NULL,
+};
+ATTRIBUTE_GROUPS(isl12022_hwmon);
+
+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_groups(dev, "isl12022", isl12022,
+ isl12022_hwmon_groups);
+ 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.
@@ -179,6 +258,8 @@ 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