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authorAdam Ward <adam.ward.opensource@diasemi.com>2015-04-16 12:45:26 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-04-17 09:04:00 -0400
commit03cc1625e1f2e9fc6910af4174c942d56292f556 (patch)
treecab9d331c2d2d16be6e360bf70d2a5255f51adf5 /drivers
parent52ef84d566dc145b4d469f06667c5fa3118fdd44 (diff)
downloadlinux-03cc1625e1f2e9fc6910af4174c942d56292f556.tar.bz2
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/rtc/rtc-da9052.c87
1 files changed, 66 insertions, 21 deletions
diff --git a/drivers/rtc/rtc-da9052.c b/drivers/rtc/rtc-da9052.c
index 613c43b7e9ae..ead02fad2de5 100644
--- a/drivers/rtc/rtc-da9052.c
+++ b/drivers/rtc/rtc-da9052.c
@@ -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)