summaryrefslogtreecommitdiff
path: root/drivers/rtc
diff options
context:
space:
mode:
Diffstat (limited to 'drivers/rtc')
-rw-r--r--drivers/rtc/rtc-s35390a.c65
1 files changed, 55 insertions, 10 deletions
diff --git a/drivers/rtc/rtc-s35390a.c b/drivers/rtc/rtc-s35390a.c
index 6507a01cf9ad..6c90c9f48cab 100644
--- a/drivers/rtc/rtc-s35390a.c
+++ b/drivers/rtc/rtc-s35390a.c
@@ -15,6 +15,7 @@
#include <linux/bitrev.h>
#include <linux/bcd.h>
#include <linux/slab.h>
+#include <linux/delay.h>
#define S35390A_CMD_STATUS1 0
#define S35390A_CMD_STATUS2 1
@@ -94,19 +95,63 @@ static int s35390a_get_reg(struct s35390a *s35390a, int reg, char *buf, int len)
return 0;
}
-static int s35390a_reset(struct s35390a *s35390a)
+/*
+ * Returns <0 on error, 0 if rtc is setup fine and 1 if the chip was reset.
+ * To keep the information if an irq is pending, pass the value read from
+ * STATUS1 to the caller.
+ */
+static int s35390a_reset(struct s35390a *s35390a, char *status1)
{
- char buf[1];
+ char buf;
+ int ret;
+ unsigned initcount = 0;
- if (s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf)) < 0)
- return -EIO;
+ ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, status1, 1);
+ if (ret < 0)
+ return ret;
- if (!(buf[0] & (S35390A_FLAG_POC | S35390A_FLAG_BLD)))
+ if (*status1 & S35390A_FLAG_POC)
+ /*
+ * Do not communicate for 0.5 seconds since the power-on
+ * detection circuit is in operation.
+ */
+ msleep(500);
+ else if (!(*status1 & S35390A_FLAG_BLD))
+ /*
+ * If both POC and BLD are unset everything is fine.
+ */
return 0;
- buf[0] |= (S35390A_FLAG_RESET | S35390A_FLAG_24H);
- buf[0] &= 0xf0;
- return s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, buf, sizeof(buf));
+ /*
+ * At least one of POC and BLD are set, so reinitialise chip. Keeping
+ * this information in the hardware to know later that the time isn't
+ * valid is unfortunately not possible because POC and BLD are cleared
+ * on read. So the reset is best done now.
+ *
+ * The 24H bit is kept over reset, so set it already here.
+ */
+initialize:
+ *status1 = S35390A_FLAG_24H;
+ buf = S35390A_FLAG_RESET | S35390A_FLAG_24H;
+ ret = s35390a_set_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
+
+ if (ret < 0)
+ return ret;
+
+ ret = s35390a_get_reg(s35390a, S35390A_CMD_STATUS1, &buf, 1);
+ if (ret < 0)
+ return ret;
+
+ if (buf & (S35390A_FLAG_POC | S35390A_FLAG_BLD)) {
+ /* Try up to five times to reset the chip */
+ if (initcount < 5) {
+ ++initcount;
+ goto initialize;
+ } else
+ return -EIO;
+ }
+
+ return 1;
}
static int s35390a_disable_test_mode(struct s35390a *s35390a)
@@ -353,7 +398,7 @@ static int s35390a_probe(struct i2c_client *client,
unsigned int i;
struct s35390a *s35390a;
struct rtc_time tm;
- char buf[1];
+ char buf[1], status1;
if (!i2c_check_functionality(client->adapter, I2C_FUNC_I2C)) {
err = -ENODEV;
@@ -382,7 +427,7 @@ static int s35390a_probe(struct i2c_client *client,
}
}
- err = s35390a_reset(s35390a);
+ err = s35390a_reset(s35390a, &status1);
if (err < 0) {
dev_err(&client->dev, "error resetting chip\n");
goto exit_dummy;