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drivers/rtc/rtc-da9052.c: add extra reads with timeouts to avoid returning partially updated values 

The RTC is in a different clock domain so a quick read after write
can retrieve a mangled value of the old/new values

Signed-off-by: Adam Ward <adam.ward.opensource@diasemi.com>
Tested-by: Adam Ward <adam.ward.opensource@diasemi.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Adam Ward 2015-04-16 12:45:26 -07:00 committed by Linus Torvalds
parent 52ef84d566
commit 03cc1625e1
1 changed files with 66 additions and 21 deletions
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87
drivers/rtc/rtc-da9052.c
View File

@ -16,6 +16,7 @@
#include <linux/platform_device.h>
#include <linux/rtc.h>
#include <linux/err.h>
#include <linux/delay.h>
#include <linux/mfd/da9052/da9052.h>
#include <linux/mfd/da9052/reg.h>
@ -23,6 +24,8 @@
#define rtc_err(rtc, fmt, ...) \
dev_err(rtc->da9052->dev, "%s: " fmt, __func__, ##__VA_ARGS__)
#define DA9052_GET_TIME_RETRIES 5
struct da9052_rtc {
struct rtc_device *rtc;
struct da9052 *da9052;
@ -58,22 +61,43 @@ static irqreturn_t da9052_rtc_irq(int irq, void *data)
static int da9052_read_alarm(struct da9052_rtc *rtc, struct rtc_time *rtc_tm)
{
int ret;
uint8_t v[5];
uint8_t v[2][5];
int idx = 1;
int timeout = DA9052_GET_TIME_RETRIES;
ret = da9052_group_read(rtc->da9052, DA9052_ALARM_MI_REG, 5, v);
if (ret != 0) {
ret = da9052_group_read(rtc->da9052, DA9052_ALARM_MI_REG, 5, &v[0][0]);
if (ret) {
rtc_err(rtc, "Failed to group read ALM: %d\n", ret);
return ret;
}
rtc_tm->tm_year = (v[4] & DA9052_RTC_YEAR) + 100;
rtc_tm->tm_mon = (v[3] & DA9052_RTC_MONTH) - 1;
rtc_tm->tm_mday = v[2] & DA9052_RTC_DAY;
rtc_tm->tm_hour = v[1] & DA9052_RTC_HOUR;
rtc_tm->tm_min = v[0] & DA9052_RTC_MIN;
do {
ret = da9052_group_read(rtc->da9052,
DA9052_ALARM_MI_REG, 5, &v[idx][0]);
if (ret) {
rtc_err(rtc, "Failed to group read ALM: %d\n", ret);
return ret;
}
ret = rtc_valid_tm(rtc_tm);
return ret;
if (memcmp(&v[0][0], &v[1][0], 5) == 0) {
rtc_tm->tm_year = (v[0][4] & DA9052_RTC_YEAR) + 100;
rtc_tm->tm_mon = (v[0][3] & DA9052_RTC_MONTH) - 1;
rtc_tm->tm_mday = v[0][2] & DA9052_RTC_DAY;
rtc_tm->tm_hour = v[0][1] & DA9052_RTC_HOUR;
rtc_tm->tm_min = v[0][0] & DA9052_RTC_MIN;
ret = rtc_valid_tm(rtc_tm);
return ret;
}
idx = (1-idx);
msleep(20);
} while (timeout--);
rtc_err(rtc, "Timed out reading alarm time\n");
return -EIO;
}
static int da9052_set_alarm(struct da9052_rtc *rtc, struct rtc_time *rtc_tm)
@ -135,24 +159,45 @@ static int da9052_rtc_get_alarm_status(struct da9052_rtc *rtc)
static int da9052_rtc_read_time(struct device *dev, struct rtc_time *rtc_tm)
{
struct da9052_rtc *rtc = dev_get_drvdata(dev);
uint8_t v[6];
int ret;
uint8_t v[2][6];
int idx = 1;
int timeout = DA9052_GET_TIME_RETRIES;
ret = da9052_group_read(rtc->da9052, DA9052_COUNT_S_REG, 6, v);
if (ret < 0) {
ret = da9052_group_read(rtc->da9052, DA9052_COUNT_S_REG, 6, &v[0][0]);
if (ret) {
rtc_err(rtc, "Failed to read RTC time : %d\n", ret);
return ret;
}
rtc_tm->tm_year = (v[5] & DA9052_RTC_YEAR) + 100;
rtc_tm->tm_mon = (v[4] & DA9052_RTC_MONTH) - 1;
rtc_tm->tm_mday = v[3] & DA9052_RTC_DAY;
rtc_tm->tm_hour = v[2] & DA9052_RTC_HOUR;
rtc_tm->tm_min = v[1] & DA9052_RTC_MIN;
rtc_tm->tm_sec = v[0] & DA9052_RTC_SEC;
do {
ret = da9052_group_read(rtc->da9052,
DA9052_COUNT_S_REG, 6, &v[idx][0]);
if (ret) {
rtc_err(rtc, "Failed to read RTC time : %d\n", ret);
return ret;
}
ret = rtc_valid_tm(rtc_tm);
return ret;
if (memcmp(&v[0][0], &v[1][0], 6) == 0) {
rtc_tm->tm_year = (v[0][5] & DA9052_RTC_YEAR) + 100;
rtc_tm->tm_mon = (v[0][4] & DA9052_RTC_MONTH) - 1;
rtc_tm->tm_mday = v[0][3] & DA9052_RTC_DAY;
rtc_tm->tm_hour = v[0][2] & DA9052_RTC_HOUR;
rtc_tm->tm_min = v[0][1] & DA9052_RTC_MIN;
rtc_tm->tm_sec = v[0][0] & DA9052_RTC_SEC;
ret = rtc_valid_tm(rtc_tm);
return ret;
}
idx = (1-idx);
msleep(20);
} while (timeout--);
rtc_err(rtc, "Timed out reading time\n");
return -EIO;
}
static int da9052_rtc_set_time(struct device *dev, struct rtc_time *tm)