rtc: spacemit: handle regmap_test_bits() error return

p1_rtc_read_time() called if (!regmap_test_bits(regmap, RTC_CTRL, RTC_EN))
to check if the RTC was enabled.

regmap_test_bits() returns 1 if the bit is set, 0 if not set, and a
negative error code (e.g. -EIO) if reading the control register fails.
Using !regmap_test_bits(...) evaluates a negative error code as boolean
false, causing I2C/regmap read failures to be ignored and incorrectly
proceeding to read time registers from a failing device.

Fix this by capturing the return value of regmap_test_bits() and returning
the error code if negative, or -EINVAL if the RTC is disabled.

Fixes: a6de182daa2b ("rtc: spacemit: support the SpacemiT P1 RTC")
Reviewed-by: Alex Elder <elder@riscstar.com>
Signed-off-by: Surendra Singh Chouhan <kr494167@gmail.com>
Link: https://patch.msgid.link/20260724135803.81223-1-kr494167@gmail.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-spacemit-p1.c b/drivers/rtc/rtc-spacemit-p1.c
index 43ab624..1de7bd9 100644 (file)
--- a/drivers/rtc/rtc-spacemit-p1.c
+++ b/drivers/rtc/rtc-spacemit-p1.c
@@ -57,8 +57,9 @@ static int p1_rtc_read_time(struct device *dev, struct rtc_time *t)
        u8 time[6];
        int ret;
 
-       if (!regmap_test_bits(regmap, RTC_CTRL, RTC_EN))
-               return -EINVAL;         /* RTC is disabled */
+       ret = regmap_test_bits(regmap, RTC_CTRL, RTC_EN);
+       if (ret <= 0)
+               return ret ?: -EINVAL;  /* RTC is disabled or error */
 
        ret = regmap_bulk_read(regmap, RTC_TIME, time, sizeof(time));
        if (ret)