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

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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

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