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 #include #include +#include #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;