[v5] rtc: pcf85363/pcf85263: fix error that failed to run hwclock -w

[v5] rtc: pcf85363/pcf85263: fix error that failed to run hwclock -w

[Biwen Li]

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

Why:
    - Relative commit: 8b9f9d4dc511309918c4f6793bae7387c0c638af, 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>
---
Change in v5:
	- drop robust explanation

Change in v4:
	- use old scheme
	- replace link to lkml.org with commit
	- add proper explanation

Change in v3:
	- replace old scheme with new scheme:
	  increase max_register.

Change in v2:
	- add Why and How into commit message.

 drivers/rtc/rtc-pcf85363.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/drivers/rtc/rtc-pcf85363.c b/drivers/rtc/rtc-pcf85363.c
index a075e77617dc..3450d615974d 100644
--- a/drivers/rtc/rtc-pcf85363.c
+++ b/drivers/rtc/rtc-pcf85363.c
@@ -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;
 
-- 
2.17.1

Re: [v5] rtc: pcf85363/pcf85263: fix error that failed to run hwclock -w

[Nandor Han]

On 8/29/19 5:14 AM, Biwen Li wrote:
> Issue:
>      - # hwclock -w
>        hwclock: RTC_SET_TIME: Invalid argument
> 
> Why:
>      - Relative commit: 8b9f9d4dc511309918c4f6793bae7387c0c638af, 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>
> ---
> Change in v5:
> 	- drop robust explanation
> 

LGTM +1

Nandor

Re: [v5] rtc: pcf85363/pcf85263: fix error that failed to run hwclock -w

[Alexandre Belloni]

On 29/08/2019 10:14:18+0800, Biwen Li wrote:
> Issue:
>     - # hwclock -w
>       hwclock: RTC_SET_TIME: Invalid argument
> 
> Why:
>     - Relative commit: 8b9f9d4dc511309918c4f6793bae7387c0c638af, 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>
> ---
> Change in v5:
> 	- drop robust explanation
> 
> Change in v4:
> 	- use old scheme
> 	- replace link to lkml.org with commit
> 	- add proper explanation
> 
> Change in v3:
> 	- replace old scheme with new scheme:
> 	  increase max_register.
> 
> Change in v2:
> 	- add Why and How into commit message.
> 
>  drivers/rtc/rtc-pcf85363.c | 7 ++++++-
>  1 file changed, 6 insertions(+), 1 deletion(-)
> 
Applied, thanks.

-- 
Alexandre Belloni, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com