[PATCH v2 4/8] rtc: isl12022: add support for trip level DT bindings

[Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>]

Implement support for using the values given in the
isil,trip-level[87]5-microvolt properties to set appropriate values in
the VB[87]5TP bits in the PWR_VBAT register.

Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
---
 drivers/rtc/rtc-isl12022.c | 36 ++++++++++++++++++++++++++++++++++++
 1 file changed, 36 insertions(+)

diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c
index ebd66b835cef..50bbd1fefad8 100644
--- a/drivers/rtc/rtc-isl12022.c
+++ b/drivers/rtc/rtc-isl12022.c
@@ -9,6 +9,7 @@
  */
 
 #include <linux/bcd.h>
+#include <linux/bitfield.h>
 #include <linux/err.h>
 #include <linux/hwmon.h>
 #include <linux/i2c.h>
@@ -31,6 +32,8 @@
 #define ISL12022_REG_SR		0x07
 #define ISL12022_REG_INT	0x08
 
+#define ISL12022_REG_PWR_VBAT	0x0a
+
 #define ISL12022_REG_BETA	0x0d
 #define ISL12022_REG_TEMP_L	0x28
 
@@ -42,6 +45,9 @@
 
 #define ISL12022_INT_WRTC	(1 << 6)
 
+#define ISL12022_REG_VB85_MASK	GENMASK(5, 3)
+#define ISL12022_REG_VB75_MASK	GENMASK(2, 0)
+
 #define ISL12022_BETA_TSE	(1 << 7)
 
 static umode_t isl12022_hwmon_is_visible(const void *data,
@@ -209,6 +215,35 @@ static const struct regmap_config regmap_config = {
 	.use_single_write = true,
 };
 
+static const u32 trip_level85[] = { 2125000, 2295000, 2550000, 2805000, 3060000, 4250000, 4675000 };
+static const u32 trip_level75[] = { 1875000, 2025000, 2250000, 2475000, 2700000, 3750000, 4125000 };
+
+static void isl12022_set_trip_levels(struct device *dev)
+{
+	struct regmap *regmap = dev_get_drvdata(dev);
+	u32 level85 = 0, level75 = 0;
+	int ret, x85, x75;
+	u8 val, mask;
+
+	device_property_read_u32(dev, "isil,trip-level85-microvolt", &level85);
+	device_property_read_u32(dev, "isil,trip-level75-microvolt", &level75);
+
+	for (x85 = 0; x85 < ARRAY_SIZE(trip_level85) - 1; x85++)
+		if (level85 <= trip_level85[x85])
+			break;
+
+	for (x75 = 0; x75 < ARRAY_SIZE(trip_level75) - 1; x75++)
+		if (level75 <= trip_level75[x75])
+			break;
+
+	val = FIELD_PREP(ISL12022_REG_VB85_MASK, x85) | FIELD_PREP(ISL12022_REG_VB75_MASK, x75);
+	mask = ISL12022_REG_VB85_MASK | ISL12022_REG_VB75_MASK;
+
+	ret = regmap_update_bits(regmap, ISL12022_REG_PWR_VBAT, mask, val);
+	if (ret)
+		dev_warn(dev, "unable to set battery alarm levels: %d\n", ret);
+}
+
 static int isl12022_probe(struct i2c_client *client)
 {
 	struct rtc_device *rtc;
@@ -225,6 +260,7 @@ static int isl12022_probe(struct i2c_client *client)
 
 	dev_set_drvdata(&client->dev, regmap);
 
+	isl12022_set_trip_levels(&client->dev);
 	isl12022_hwmon_register(&client->dev);
 
 	rtc = devm_rtc_allocate_device(&client->dev);
-- 
2.37.2