rtc: rv3029: remove race condition when update STATUS

There is no lock preventing concurrent access to the status register from
bth the rtc subsystem and the hwmon subsystem. Use regmap_update_bits to
ensure updating RV3029_STATUS is properly locked.

Link: https://lore.kernel.org/r/20191214221022.622482-5-alexandre.belloni@bootlin.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>

diff --git a/drivers/rtc/rtc-rv3029c2.c b/drivers/rtc/rtc-rv3029c2.c
index 9a0397f3dee9a4fe564de3a4917ad5aca676acb4..421c6670813805b8e63dffeeac2b286a7b6a0764 100644 (file)
--- a/drivers/rtc/rtc-rv3029c2.c
+++ b/drivers/rtc/rtc-rv3029c2.c
@@ -147,19 +147,6 @@ static int rv3029_get_sr(struct device *dev, u8 *buf)
        return 0;
 }
 
-static int rv3029_set_sr(struct device *dev, u8 val)
-{
-       u8 buf[1];
-       int sr;
-
-       buf[0] = val;
-       sr = rv3029_write_regs(dev, RV3029_STATUS, buf, 1);
-       dev_dbg(dev, "status = 0x%.2x (%d)\n", buf[0], buf[0]);
-       if (sr < 0)
-               return -EIO;
-       return 0;
-}
-
 static int rv3029_eeprom_busywait(struct device *dev)
 {
        int i, ret;
@@ -205,9 +192,9 @@ static int rv3029_eeprom_enter(struct device *dev)
                /* We clear the bits and retry once just in case
                 * we had a brown out in early startup.
                 */
-               sr &= ~RV3029_STATUS_VLOW1;
-               sr &= ~RV3029_STATUS_VLOW2;
-               ret = rv3029_set_sr(dev, sr);
+               ret = regmap_update_bits(rv3029->regmap, RV3029_STATUS,
+                                        RV3029_STATUS_VLOW1 |
+                                        RV3029_STATUS_VLOW2, 0);
                if (ret < 0)
                        return ret;
                usleep_range(1000, 10000);
@@ -515,6 +502,7 @@ static int rv3029_set_alarm(struct device *dev, struct rtc_wkalrm *alarm)
 
 static int rv3029_set_time(struct device *dev, struct rtc_time *tm)
 {
+       struct rv3029_data *rv3029 = dev_get_drvdata(dev);
        u8 regs[8];
        int ret;
 
@@ -539,19 +527,9 @@ static int rv3029_set_time(struct device *dev, struct rtc_time *tm)
        if (ret < 0)
                return ret;
 
-       ret = rv3029_get_sr(dev, regs);
-       if (ret < 0) {
-               dev_err(dev, "%s: reading SR failed\n", __func__);
-               return ret;
-       }
        /* clear PON bit */
-       ret = rv3029_set_sr(dev, (regs[0] & ~RV3029_STATUS_PON));
-       if (ret < 0) {
-               dev_err(dev, "%s: reading SR failed\n", __func__);
-               return ret;
-       }
-
-       return 0;
+       return regmap_update_bits(rv3029->regmap, RV3029_STATUS,
+                                 RV3029_STATUS_PON, 0);
 }
 
 static const struct rv3029_trickle_tab_elem {