[PATCH v3 1/1] lib/utils: consider ':' in stdout-path

[Heinrich Schuchardt]

On 5/28/21 7:58 PM, Atish Patra wrote:
> On Fri, May 28, 2021 at 10:06 AM Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>>
>> The value of the /chosen/stdout-path devicetree property is used to
>> determine the UART used by openSBI. According to the devicetree
>> specification the value may contain a hyphen, e.g.
>>
>>          chosen {
>>                  stdout-path = "/serial at f00:115200";
>>          };
>>
>> If the character ':' is present, it terminates the path of the device.
>>
>> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
>> ---
>> v3:
>>          * Use fdt_path_offset_namelen() if stdout-path contains a ':'
>>            (thanks Atish).
>>          * Fix typo %s/pointed/pointed to/.
>> ---
>>   lib/utils/serial/fdt_serial.c | 15 ++++++++++++---
>>   1 file changed, 12 insertions(+), 3 deletions(-)
>>
>> diff --git a/lib/utils/serial/fdt_serial.c b/lib/utils/serial/fdt_serial.c
>> index 25982ec..1d1eba8 100644
>> --- a/lib/utils/serial/fdt_serial.c
>> +++ b/lib/utils/serial/fdt_serial.c
>> @@ -42,12 +42,21 @@ int fdt_serial_init(void)
>>          int pos, noff = -1, len, coff, rc;
>>          void *fdt = sbi_scratch_thishart_arg1_ptr();
>>
>> -       /* Find offset of node pointed by stdout-path */
>> +       /* Find offset of node pointed to by stdout-path */
>>          coff = fdt_path_offset(fdt, "/chosen");
>>          if (-1 < coff) {
>>                  prop = fdt_getprop(fdt, coff, "stdout-path", &len);
>> -               if (prop && len)
>> -                       noff = fdt_path_offset(fdt, prop);
>> +               if (prop && len) {
>> +                       const char *sep, *start = prop;
>> +
>> +                       /* The device path may be followed by ':' */
>> +                       sep = strchr(start, ':');
>> +                       if (sep)
>> +                               noff = fdt_path_offset_namelen(fdt, prop,
>> +                                                              sep - start);
>> +                       else
>> +                               noff = fdt_path_offset(fdt, prop);
>
> We can further simplify this by passing strlen() to
> fdt_path_offset_namelen if ": "
> is not present. But that's just personal preference.

Calling fdt_path_offset_namelen() with strlen() is what
fdt_path_offset() is actually doing.

The code above results in the smaller code size and is well readable.

Thank you for reviewing.

Best regards

Heinrich

>
> I am fine with this version as well.
>
>> +               }
>>          }
>>
>>          /* First check DT node pointed by stdout-path */
>> --
>> 2.30.2
>>
>
> Either way,
>
> Reviewed-by: Atish Patra <atish.patra at wdc.com>
>