[PATCH v3 2/3] timer: cadence: Add bind function to driver

[Sean Anderson]

On 10/14/21 11:09 AM, Simon Glass wrote:
> Hi Michal,
>
> On Wed, 6 Oct 2021 at 08:19, Michal Simek <michal.simek at xilinx.com> wrote:
>>
>> When DT node has pwm-cells property it shouldn't be bind as timer driver
>> but as PWM driver. That's why make sure that this property is checked.
>>
>> Signed-off-by: Michal Simek <michal.simek at xilinx.com>
>> ---
>>
>> Changes in v3:
>> - New patch in series
>>
>>  drivers/timer/cadence-ttc.c | 12 ++++++++++++
>>  1 file changed, 12 insertions(+)
>>
>
> Why not have two compatible strings?

As I understand it, because the hardware is the same, it should have the
same compatible string.

>> diff --git a/drivers/timer/cadence-ttc.c b/drivers/timer/cadence-ttc.c
>> index 2f95d45ecd7a..2eff45060ad6 100644
>> --- a/drivers/timer/cadence-ttc.c
>> +++ b/drivers/timer/cadence-ttc.c
>> @@ -97,6 +97,17 @@ static int cadence_ttc_of_to_plat(struct udevice *dev)
>>         return 0;
>>  }
>>
>> +static int cadence_ttc_bind(struct udevice *dev)
>> +{
>> +       const char *cells;
>> +
>> +       cells = dev_read_prop(dev, "#pwm-cells", NULL);
>> +       if (cells)
>> +               return -ENODEV;
>
> We can read properties in bind() when necessary, but this is very
> strange...it seems like the bindings are messed up?

This is the preferred way to select between a PWM and a timer driver.
See e.g. Rob's comment for xlnx,pwm at [1].

--Sean

[1] https://lore.kernel.org/linux-pwm/20210513021631.GA878860@robh.at.kernel.org/

>> +
>> +       return 0;
>> +}
>> +
>>  static const struct timer_ops cadence_ttc_ops = {
>>         .get_count = cadence_ttc_get_count,
>>  };
>> @@ -114,4 +125,5 @@ U_BOOT_DRIVER(cadence_ttc) = {
>>         .priv_auto      = sizeof(struct cadence_ttc_priv),
>>         .probe = cadence_ttc_probe,
>>         .ops = &cadence_ttc_ops,
>> +       .bind = cadence_ttc_bind,
>>  };
>> --
>> 2.33.0
>>
>
> Regards,
> Simon
>