Since the meaning of the SR_LBAT85 and SR_LBAT75 bits are different in
battery backup mode, they may very well be set after power on, and
stay set for up to a minute (i.e. until the battery detection in VDD
mode happens when the seconds counter hits 59). This would mean that
userspace doing a ioctl(RTC_VL_READ) early on could get a false
positive.
The battery level detection can also be triggered by explicitly
writing a 1 to the TSE bit in the BETA register. Do that once during
boot (well, probe), and emit a single warning to the kernel log if the
battery is already low.
Signed-off-by: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
---
drivers/rtc/rtc-isl12022.c | 19 ++++++++++++++++++-
1 file changed, 18 insertions(+), 1 deletion(-)
diff --git a/drivers/rtc/rtc-isl12022.c b/drivers/rtc/rtc-isl12022.c
index 1b6659a9b33a..690dbb446d1a 100644
--- a/drivers/rtc/rtc-isl12022.c
+++ b/drivers/rtc/rtc-isl12022.c
@@ -280,8 +280,25 @@ static void isl12022_set_trip_levels(struct device *dev)
mask = ISL12022_REG_VB85_MASK | ISL12022_REG_VB75_MASK;
ret = regmap_update_bits(regmap, ISL12022_REG_PWR_VBAT, mask, val);
- if (ret)
+ if (ret) {
dev_warn(dev, "unable to set battery alarm levels: %d\n", ret);
+ return;
+ }
+
+ ret = regmap_write_bits(regmap, ISL12022_REG_BETA,
+ ISL12022_BETA_TSE, ISL12022_BETA_TSE);
+ if (ret) {
+ dev_warn(dev, "unable to trigger battery level detection: %d\n", ret);
+ return;
+ }
+
+ ret = isl12022_read_sr(regmap);
+ if (ret < 0) {
+ dev_warn(dev, "unable to read status register: %d\n", ret);
+ } else if (ret & (ISL12022_SR_LBAT85 | ISL12022_SR_LBAT75)) {
+ dev_warn(dev, "battery voltage is below %u%%\n",
+ (ret & ISL12022_SR_LBAT75) ? 75 : 85);
+ }
}
static int isl12022_probe(struct i2c_client *client)
--
2.37.2
