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Commit 03cc1625 authored by Adam Ward's avatar Adam Ward Committed by Linus Torvalds
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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: default avatarAdam Ward <adam.ward.opensource@diasemi.com>
Tested-by: default avatarAdam Ward <adam.ward.opensource@diasemi.com>
Cc: Alessandro Zummo <a.zummo@towertech.it>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 52ef84d5

drivers/rtc/rtc-da9052.c

+66 −21
Original line number Diff line number Diff line
@@ -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;
@@ -58,24 +61,45 @@ 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;

	}



	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;

		}



	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;

		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)

{

	struct da9052 *da9052 = rtc->da9052;
@@ -135,26 +159,47 @@ 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;

	}



	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;

		}



	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;

		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)

{

	struct da9052_rtc *rtc;