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rtc: pcf85363/pcf85263: fix regmap error in set_time

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Issue:
    - # hwclock -w
      hwclock: RTC_SET_TIME: Invalid argument

Why:
    - Relative commit: 8b9f9d4dc5 ("regmap: verify if register is
      writeable before writing operations"), this patch
      will always check for unwritable registers, it will compare reg
      with max_register in regmap_writeable.

    - The pcf85363/pcf85263 has the capability of address wrapping
      which means if you access an address outside the allowed range
      (0x00-0x2f) hardware actually wraps the access to a lower address.
      The rtc-pcf85363 driver will use this feature to configure the time
      and execute 2 actions in the same i2c write operation (stopping the
      clock and configure the time). However the driver has also
      configured the `regmap maxregister` protection mechanism that will
      block accessing addresses outside valid range (0x00-0x2f).

How:
    - Split of writing regs to two parts, first part writes control
      registers about stop_enable and resets, second part writes
      RTC time and date registers.

Signed-off-by: Biwen Li <biwen.li@nxp.com>
Link: https://lore.kernel.org/r/20190829021418.4607-1-biwen.li@nxp.com
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
This commit is contained in:
Biwen Li 2019-08-29 10:14:18 +08:00 committed by Alexandre Belloni
parent c59a9fc727
commit 7ef66122bd
1 changed files with 6 additions and 1 deletions
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7
drivers/rtc/rtc-pcf85363.c
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@ -166,7 +166,12 @@ static int pcf85363_rtc_set_time(struct device *dev, struct rtc_time *tm)
buf[DT_YEARS] = bin2bcd(tm->tm_year % 100);
ret = regmap_bulk_write(pcf85363->regmap, CTRL_STOP_EN,
tmp, sizeof(tmp));
tmp, 2);
if (ret)
return ret;
ret = regmap_bulk_write(pcf85363->regmap, DT_100THS,
buf, sizeof(tmp) - 2);
if (ret)
return ret;