Re: [PATCH V4 3/3] pwm: pxa: add device tree support

From: Chao Xie
Date: Mon May 13 2013 - 01:04:42 EST


>> + const struct of_device_id *of_id =
>> + of_match_device(pxa_pwm_of_match, &pdev->dev);
>> + unsigned int npwm;
>> +
>> + if (!of_id)
>> + return -ENODEV;
>> +
>> + npwm = (unsigned int)of_id->data;
>> + pwm->chip.npwm = (npwm & HAS_SECONDARY_PWM) ? 2 : 1;
>> +
>> + return 0;
>> +}
>> +
>> static int pwm_probe(struct platform_device *pdev)
>> {
>> const struct platform_device_id *id = platform_get_device_id(pdev);
>> @@ -144,7 +180,6 @@ static int pwm_probe(struct platform_device *pdev)
>> pwm->chip.dev = &pdev->dev;
>> pwm->chip.ops = &pxa_pwm_ops;
>> pwm->chip.base = -1;
>> - pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
>>
>> r = platform_get_resource(pdev, IORESOURCE_MEM, 0);
>> if (r == NULL) {
>> @@ -156,6 +191,20 @@ static int pwm_probe(struct platform_device *pdev)
>> if (IS_ERR(pwm->mmio_base))
>> return PTR_ERR(pwm->mmio_base);
>>
>> + if (!id) {
>> + if (IS_ENABLED(CONFIG_OF))
>> + ret = pxa_pwm_parse_data_dt(pdev, pwm);
>> + else
>> + ret = -ENODEV;
>> + } else {
>> + pwm->chip.npwm = (id->driver_data & HAS_SECONDARY_PWM) ? 2 : 1;
>> + }
>
> ^^ braces not necessarily here, and I'm not really sure if we should check
> CONFIG_OF firstly, and leave the platform_device_id thing as a legacy
> fall back, what do you think?
>
> if (IS_ENABLED(CONFIG_OF)) {
> ...
> } else {
> const struct platform_device_id *id = platform_get_device_id(...);
> ...
> }
>
it has some reasons.
You ways works for
1. PWM defined in DT configuration file and CONFIG_OF is defined
2. CONFIG_OF is not defined.
If COFNIG_OF is defined, but PWM is not defined in device tree
configuration file. The device
can still match the driver is the id_table is matched or name is matched.
So I covered addtional situation
1. PWM is not defined in DT configuration file but CONFIG_OF is defined.

So i keep the possiblility that event CONFIG_OF is defined, but PWM is
not defined in DT file, and we still can use old way to probe the
device.

>> +
>> + if (ret) {
>> + dev_err(&pdev->dev, "failed to parse data from device id\n");
>> + return ret;
>> + }
>> +
>> ret = pwmchip_add(&pwm->chip);
>> if (ret < 0) {
>> dev_err(&pdev->dev, "pwmchip_add() failed: %d\n", ret);
>> @@ -181,6 +230,7 @@ static struct platform_driver pwm_driver = {
>> .driver = {
>> .name = "pxa25x-pwm",
>> .owner = THIS_MODULE,
>> + .of_match_table = pxa_pwm_of_match,
>> },
>> .probe = pwm_probe,
>> .remove = pwm_remove,
>> --
>> 1.7.4.1
>>
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