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Subject[PATCH 04/16] rtc: rv3029: remove race condition when update STATUS
Date
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.

Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---
drivers/rtc/rtc-rv3029c2.c | 34 ++++++----------------------------
1 file changed, 6 insertions(+), 28 deletions(-)

diff --git a/drivers/rtc/rtc-rv3029c2.c b/drivers/rtc/rtc-rv3029c2.c
index 36b4da260caf..4e7514433b79 100644
--- 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 {
--
2.23.0
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