target/linux/bcm27xx/patches-6.1/950-0356-rtc-pcf8523-Fix-oscillator-stop-bit-handling.patch

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