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authorAlexandre Belloni <alexandre.belloni@bootlin.com>2019-04-30 11:28:20 +0200
committerAlexandre Belloni <alexandre.belloni@bootlin.com>2019-04-30 11:50:22 +0200
commit7fe8fcee0cf90ef9aa4c6a123b8b6c3925ccded1 (patch)
treeb65c529efa59ec73bb5bc0b8a120222ce01b6ba7 /drivers/rtc
parent3b2dc19ff9a1495cf08752b5a1ba8b986473f39f (diff)
downloadlinux-7fe8fcee0cf90ef9aa4c6a123b8b6c3925ccded1.tar.bz2
rtc: jz4740: rework invalid time detection
The scratchpad register is used to detect an invalid time when power to the RTC has been lost. Instead of deleting that precious information and set the time to the UNIX epoch, forward it to userspace. Tested-by: Mathieu Malaterre <malat@debian.org> Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
Diffstat (limited to 'drivers/rtc')
-rw-r--r--drivers/rtc/rtc-jz4740.c21
1 files changed, 9 insertions, 12 deletions
diff --git a/drivers/rtc/rtc-jz4740.c b/drivers/rtc/rtc-jz4740.c
index 32e6b6270efd..6dd00b654f93 100644
--- a/drivers/rtc/rtc-jz4740.c
+++ b/drivers/rtc/rtc-jz4740.c
@@ -157,6 +157,9 @@ static int jz4740_rtc_read_time(struct device *dev, struct rtc_time *time)
uint32_t secs, secs2;
int timeout = 5;
+ if (jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SCRATCHPAD) != 0x12345678)
+ return -EINVAL;
+
/* If the seconds register is read while it is updated, it can contain a
* bogus value. This can be avoided by making sure that two consecutive
* reads have the same value.
@@ -180,8 +183,13 @@ static int jz4740_rtc_read_time(struct device *dev, struct rtc_time *time)
static int jz4740_rtc_set_time(struct device *dev, struct rtc_time *time)
{
struct jz4740_rtc *rtc = dev_get_drvdata(dev);
+ int ret;
+
+ ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, rtc_tm_to_time64(time));
+ if (ret)
+ return ret;
- return jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, rtc_tm_to_time64(time));
+ return jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SCRATCHPAD, 0x12345678);
}
static int jz4740_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *alrm)
@@ -308,7 +316,6 @@ static int jz4740_rtc_probe(struct platform_device *pdev)
{
int ret;
struct jz4740_rtc *rtc;
- uint32_t scratchpad;
struct resource *mem;
const struct platform_device_id *id = platform_get_device_id(pdev);
const struct of_device_id *of_id = of_match_device(
@@ -376,16 +383,6 @@ static int jz4740_rtc_probe(struct platform_device *pdev)
return ret;
}
- scratchpad = jz4740_rtc_reg_read(rtc, JZ_REG_RTC_SCRATCHPAD);
- if (scratchpad != 0x12345678) {
- ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SCRATCHPAD, 0x12345678);
- ret = jz4740_rtc_reg_write(rtc, JZ_REG_RTC_SEC, 0);
- if (ret) {
- dev_err(&pdev->dev, "Could not write to RTC registers\n");
- return ret;
- }
- }
-
if (np && of_device_is_system_power_controller(np)) {
if (!pm_power_off) {
/* Default: 60ms */