The patch titled
Subject: drivers/rtc/rtc-da9052.c: add extra reads with timeouts to avoid returning partially updated values
has been added to the -mm tree. Its filename is
rtc-da9052-add-extra-reads-with-timeouts-to-avoid-returning-partially-updated-values.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/rtc-da9052-add-extra-reads-with-timeouts-to-avoid-returning-partially-updated-values.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/rtc-da9052-add-extra-reads-with-timeouts-to-avoid-returning-partially-updated-values.patch
Before you just go and hit "reply", please:
a) Consider who else should be cc'ed
b) Prefer to cc a suitable mailing list as well
c) Ideally: find the original patch on the mailing list and do a
reply-to-all to that, adding suitable additional cc's
*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Adam Ward <adam.ward.opensource@xxxxxxxxxxx>
Subject: 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@xxxxxxxxxxx>
Tested-by: Adam Ward <adam.ward.opensource@xxxxxxxxxxx>
Cc: Alessandro Zummo <a.zummo@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
drivers/rtc/rtc-da9052.c | 87 ++++++++++++++++++++++++++++---------
1 file changed, 66 insertions(+), 21 deletions(-)
diff -puN drivers/rtc/rtc-da9052.c~rtc-da9052-add-extra-reads-with-timeouts-to-avoid-returning-partially-updated-values drivers/rtc/rtc-da9052.c
--- a/drivers/rtc/rtc-da9052.c~rtc-da9052-add-extra-reads-with-timeouts-to-avoid-returning-partially-updated-values
+++ a/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 ir
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;
+ }
+
+ 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;
+ }
- 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(s
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;
+ }
+
+ 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;
+ }
- 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)
_
Patches currently in -mm which might be from adam.ward.opensource@xxxxxxxxxxx are
rtc-da9052-add-extra-reads-with-timeouts-to-avoid-returning-partially-updated-values.patch
rtc-da9052-add-constraints-to-set-valid-year.patch
rtc-da9052-register-ability-of-alarm-to-wake-device-from-suspend.patch
--
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
