diff options
Diffstat (limited to 'drivers/rtc/rtc-s5m.c')
| -rw-r--r-- | drivers/rtc/rtc-s5m.c | 37 |
1 files changed, 31 insertions, 6 deletions
diff --git a/drivers/rtc/rtc-s5m.c b/drivers/rtc/rtc-s5m.c index 10982cdfce11..977b40cd32a7 100644 --- a/drivers/rtc/rtc-s5m.c +++ b/drivers/rtc/rtc-s5m.c @@ -28,6 +28,16 @@ #include <linux/mfd/samsung/irq.h> #include <linux/mfd/samsung/rtc.h> +/* + * Maximum number of retries for checking changes in UDR field + * of SEC_RTC_UDR_CON register (to limit possible endless loop). + * + * After writing to RTC registers (setting time or alarm) read the UDR field + * in SEC_RTC_UDR_CON register. UDR is auto-cleared when data have + * been transferred. + */ +#define UDR_READ_RETRY_CNT 5 + struct s5m_rtc_info { struct device *dev; struct sec_pmic_dev *s5m87xx; @@ -84,6 +94,25 @@ static int s5m8767_tm_to_data(struct rtc_time *tm, u8 *data) } } +/* + * Read RTC_UDR_CON register and wait till UDR field is cleared. + * This indicates that time/alarm update ended. + */ +static inline int s5m8767_wait_for_udr_update(struct s5m_rtc_info *info) +{ + int ret, retry = UDR_READ_RETRY_CNT; + unsigned int data; + + do { + ret = regmap_read(info->regmap, SEC_RTC_UDR_CON, &data); + } while (--retry && (data & RTC_UDR_MASK) && !ret); + + if (!retry) + dev_err(info->dev, "waiting for UDR update, reached max number of retries\n"); + + return ret; +} + static inline int s5m8767_rtc_set_time_reg(struct s5m_rtc_info *info) { int ret; @@ -104,9 +133,7 @@ static inline int s5m8767_rtc_set_time_reg(struct s5m_rtc_info *info) return ret; } - do { - ret = regmap_read(info->regmap, SEC_RTC_UDR_CON, &data); - } while ((data & RTC_UDR_MASK) && !ret); + ret = s5m8767_wait_for_udr_update(info); return ret; } @@ -133,9 +160,7 @@ static inline int s5m8767_rtc_set_alarm_reg(struct s5m_rtc_info *info) return ret; } - do { - ret = regmap_read(info->regmap, SEC_RTC_UDR_CON, &data); - } while ((data & RTC_UDR_MASK) && !ret); + ret = s5m8767_wait_for_udr_update(info); return ret; } |