1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
|
From d4caec563cc89319516a29a9b3c40ec302925d7a Mon Sep 17 00:00:00 2001
From: Phil Elwell <phil@raspberrypi.org>
Date: Mon, 29 Oct 2018 14:45:45 +0000
Subject: [PATCH] rtc: pcf8523: Fix oscillator stop bit handling
See: https://github.com/raspberrypi/firmware/issues/1065
Signed-off-by: Phil Elwell <phil@raspberrypi.com>
---
drivers/rtc/rtc-pcf8523.c | 29 +++++++++++++++++++++++++++--
1 file changed, 27 insertions(+), 2 deletions(-)
--- a/drivers/rtc/rtc-pcf8523.c
+++ b/drivers/rtc/rtc-pcf8523.c
@@ -100,6 +100,7 @@ static int pcf8523_rtc_read_time(struct
{
struct pcf8523 *pcf8523 = dev_get_drvdata(dev);
u8 regs[7];
+ u32 value;
int err;
err = regmap_bulk_read(pcf8523->regmap, PCF8523_REG_SECONDS, regs,
@@ -107,8 +108,32 @@ static int pcf8523_rtc_read_time(struct
if (err < 0)
return err;
- if (regs[0] & PCF8523_SECONDS_OS)
- return -EINVAL;
+ if (regs[0] & PCF8523_SECONDS_OS) {
+ /*
+ * If the oscillator was stopped, try to clear the flag. Upon
+ * power-up the flag is always set, but if we cannot clear it
+ * the oscillator isn't running properly for some reason. The
+ * sensible thing therefore is to return an error, signalling
+ * that the clock cannot be assumed to be correct.
+ */
+
+ regs[0] &= ~PCF8523_SECONDS_OS;
+
+ err = regmap_write(pcf8523->regmap, PCF8523_REG_SECONDS,
+ regs[0]);
+ if (err < 0)
+ return err;
+
+ err = regmap_read(pcf8523->regmap, PCF8523_REG_SECONDS,
+ &value);
+ if (err < 0)
+ return err;
+
+ if (value & PCF8523_SECONDS_OS)
+ return -EAGAIN;
+
+ regs[0] = value;
+ }
tm->tm_sec = bcd2bin(regs[0] & 0x7f);
tm->tm_min = bcd2bin(regs[1] & 0x7f);
|