Re: [PATCH 3/3] leds-pwm.c: support ACPI via firmware-node framework

[Nikolaus Voss <nv@xxxxxxx>]

Dan,

On Thu, 30 May 2019, Dan Murphy wrote:
> On 5/29/19 7:18 AM, Nikolaus Voss wrote:
> > DT specific handling is replaced by firmware-node abstration to support
> > ACPI specification of PWM LEDS.
> >
> > Example ASL:
> > Device (PWML)
> > {
> >      Name (_HID, "PRP0001")
> >      Name (_DSD, Package () {
> >            ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> >            Package () { Package () {"compatible",
> >                                      Package () {"pwm-leds"}}}})
> >
> >      Device (PWL0)
> >      {
> >          Name (_HID, "PRP0001")
> >          Name (_DSD, Package () {
> >                ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
> >                Package () {
> >                             Package () {"label", "alarm-led"},
> >                             Package () {"pwms", Package ()
> >                                         {\_SB_.PCI0.PWM, 0, 600000, 0}},
> >                             Package () {"linux,default-state", "off"}}})
> >      }
> > }
> >
> > Signed-off-by: Nikolaus Voss <nikolaus.voss@xxxxxxxxxxxxxxxxxxxxx>
> > ---
> >   drivers/leds/leds-pwm.c | 44 ++++++++++++++++++++++++-----------------
> >   1 file changed, 26 insertions(+), 18 deletions(-)
> >
> > diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
> > index af08bcdc4fd8..cc717dd6a12c 100644
> > --- a/drivers/leds/leds-pwm.c
> > +++ b/drivers/leds/leds-pwm.c
> > @@ -75,7 +75,7 @@ static inline size_t sizeof_pwm_leds_priv(int num_leds)
> >   }
> >
> >   static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
> > -		       struct led_pwm *led, struct device_node *child)
> > +		       struct led_pwm *led, struct fwnode_handle *fwnode)
> >   {
> >   	struct led_pwm_data *led_data = &priv->leds[priv->num_leds];
> >   	struct pwm_args pargs;
> > @@ -88,8 +88,8 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
> >   	led_data->cdev.max_brightness = led->max_brightness;
> >   	led_data->cdev.flags = LED_CORE_SUSPENDRESUME;
> >
> > -	if (child)
> > -		led_data->pwm = devm_of_pwm_get(dev, child, NULL);
> > +	if (fwnode)
> > +		led_data->pwm = devm_fwnode_pwm_get(dev, fwnode, NULL);
> >   	else
> >   		led_data->pwm = devm_pwm_get(dev, led->name);
> >   	if (IS_ERR(led_data->pwm)) {
> > @@ -114,7 +114,8 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
> >   	if (!led_data->period && (led->pwm_period_ns > 0))
> >   		led_data->period = led->pwm_period_ns;
> >
> > -	ret = devm_of_led_classdev_register(dev, child, &led_data->cdev);
> > +	ret = devm_of_led_classdev_register(dev, to_of_node(fwnode),
> > +					    &led_data->cdev);
> >   	if (ret == 0) {
> >   		priv->num_leds++;
> >   		led_pwm_set(&led_data->cdev, led_data->cdev.brightness);
> > @@ -126,27 +127,34 @@ static int led_pwm_add(struct device *dev, struct led_pwm_priv *priv,
> >   	return ret;
> >   }
> >
> > -static int led_pwm_create_of(struct device *dev, struct led_pwm_priv *priv)
> > +static int led_pwm_create_fwnode(struct device *dev, struct led_pwm_priv *priv)
> >   {
> > -	struct device_node *child;
> > +	struct fwnode_handle *fwnode;
> >   	struct led_pwm led;
> >   	int ret = 0;
> >
> >   	memset(&led, 0, sizeof(led));
> >
> > -	for_each_child_of_node(dev->of_node, child) {
> > -		led.name = of_get_property(child, "label", NULL) ? :
> > -			   child->name;
> > +	device_for_each_child_node(dev, fwnode) {
> > +		ret = fwnode_property_read_string(fwnode, "label", &led.name);
> > +		if (ret && is_of_node(fwnode))
> > +			led.name = to_of_node(fwnode)->name;
>
> new line
ok

> > +		if (!led.name) {
> > +			fwnode_handle_put(fwnode);
> > +			return -EINVAL;
> > +		}
>
> 'label' is an optional parameter for device tree returning here makes it
> required.
>
> Maybe derive a default name.  There is a patch series which is going to
> modify how labels are created for LED class devices.
>
> https://lore.kernel.org/patchwork/project/lkml/list/?series=391005

Looks interesting, thanks for the pointer. But that would be a second 
step.

My patch handles name derivation the same way as the leds-gpio driver 
already does. I think it should be handled consistently among drivers of 
the same sub-system.

Nikolaus