leds: leds-pwm: Add device tree bindings

The DT binding for the pwm-leds devices are similar to the gpio-leds type.
LEDs are represented as sub-nodes of the pwm-leds device.
The code for handling the DT boot is based on the code found in the
leds-gpio driver and adapted to use PWMs instead of GPIOs.
To avoid having custom cleanup code in case of DT boot the newly created
devm_of_pwm_get() API is used to get the correct PWM instance.

For usage see:
Documentation/devicetree/bindings/leds/leds-pwm.txt

Signed-off-by: Peter Ujfalusi <peter.ujfalusi@ti.com>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Signed-off-by: Bryan Wu <cooloney@gmail.com>

1 files changed, 92 insertions, 20 deletions

diff --git a/drivers/leds/leds-pwm.c b/drivers/leds/leds-pwm.c
index 46f4e44c6c6d..a1ea5f6a8d39 100644
--- a/drivers/leds/leds-pwm.c
+++ b/drivers/leds/leds-pwm.c
@@ -16,6 +16,7 @@
 #include <linux/kernel.h>
 #include <linux/init.h>
 #include <linux/platform_device.h>
+#include <linux/of_platform.h>
 #include <linux/fb.h>
 #include <linux/leds.h>
 #include <linux/err.h>
@@ -58,46 +59,110 @@ static inline size_t sizeof_pwm_leds_priv(int num_leds)
                       (sizeof(struct led_pwm_data) * num_leds);
 }
 
-static int led_pwm_probe(struct platform_device *pdev)
+static struct led_pwm_priv *led_pwm_create_of(struct platform_device *pdev)
 {
-        struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
+        struct device_node *node = pdev->dev.of_node;
+        struct device_node *child;
         struct led_pwm_priv *priv;
-        int i, ret = 0;
+        int count, ret;
 
-        if (!pdata)
-                return -EBUSY;
+        /* count LEDs in this device, so we know how much to allocate */
+        count = of_get_child_count(node);
+        if (!count)
+                return NULL;
 
-        priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(pdata->num_leds),
+        priv = devm_kzalloc(&pdev->dev, sizeof_pwm_leds_priv(count),
                             GFP_KERNEL);
         if (!priv)
-                return -ENOMEM;
+                return NULL;
 
-        for (i = 0; i < pdata->num_leds; i++) {
-                struct led_pwm *cur_led = &pdata->leds[i];
-                struct led_pwm_data *led_dat = &priv->leds[i];
+        for_each_child_of_node(node, child) {
+                struct led_pwm_data *led_dat = &priv->leds[priv->num_leds];
 
-                led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name);
+                led_dat->cdev.name = of_get_property(child, "label",
+                                                     NULL) ? : child->name;
+
+                led_dat->pwm = devm_of_pwm_get(&pdev->dev, child, NULL);
                 if (IS_ERR(led_dat->pwm)) {
-                        ret = PTR_ERR(led_dat->pwm);
                         dev_err(&pdev->dev, "unable to request PWM for %s\n",
-                                cur_led->name);
+                                led_dat->cdev.name);
                         goto err;
                 }
+                /* Get the period from PWM core when n*/
+                led_dat->period = pwm_get_period(led_dat->pwm);
+
+                led_dat->cdev.default_trigger = of_get_property(child,
+                                                "linux,default-trigger", NULL);
+                of_property_read_u32(child, "max-brightness",
+                                     &led_dat->cdev.max_brightness);
 
-                led_dat->cdev.name = cur_led->name;
-                led_dat->cdev.default_trigger = cur_led->default_trigger;
-                led_dat->active_low = cur_led->active_low;
-                led_dat->period = cur_led->pwm_period_ns;
                 led_dat->cdev.brightness_set = led_pwm_set;
                 led_dat->cdev.brightness = LED_OFF;
-                led_dat->cdev.max_brightness = cur_led->max_brightness;
                 led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
 
                 ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
-                if (ret < 0)
+                if (ret < 0) {
+                        dev_err(&pdev->dev, "failed to register for %s\n",
+                                led_dat->cdev.name);
+                        of_node_put(child);
                         goto err;
+                }
+                priv->num_leds++;
+        }
+
+        return priv;
+err:
+        while (priv->num_leds--)
+                led_classdev_unregister(&priv->leds[priv->num_leds].cdev);
+
+        return NULL;
+}
+
+static int led_pwm_probe(struct platform_device *pdev)
+{
+        struct led_pwm_platform_data *pdata = pdev->dev.platform_data;
+        struct led_pwm_priv *priv;
+        int i, ret = 0;
+
+        if (pdata && pdata->num_leds) {
+                priv = devm_kzalloc(&pdev->dev,
+                                    sizeof_pwm_leds_priv(pdata->num_leds),
+                                    GFP_KERNEL);
+                if (!priv)
+                        return -ENOMEM;
+
+                for (i = 0; i < pdata->num_leds; i++) {
+                        struct led_pwm *cur_led = &pdata->leds[i];
+                        struct led_pwm_data *led_dat = &priv->leds[i];
+
+                        led_dat->pwm = devm_pwm_get(&pdev->dev, cur_led->name);
+                        if (IS_ERR(led_dat->pwm)) {
+                                ret = PTR_ERR(led_dat->pwm);
+                                dev_err(&pdev->dev,
+                                        "unable to request PWM for %s\n",
+                                        cur_led->name);
+                                goto err;
+                        }
+
+                        led_dat->cdev.name = cur_led->name;
+                        led_dat->cdev.default_trigger = cur_led->default_trigger;
+                        led_dat->active_low = cur_led->active_low;
+                        led_dat->period = cur_led->pwm_period_ns;
+                        led_dat->cdev.brightness_set = led_pwm_set;
+                        led_dat->cdev.brightness = LED_OFF;
+                        led_dat->cdev.max_brightness = cur_led->max_brightness;
+                        led_dat->cdev.flags |= LED_CORE_SUSPENDRESUME;
+
+                        ret = led_classdev_register(&pdev->dev, &led_dat->cdev);
+                        if (ret < 0)
+                                goto err;
+                }
+                priv->num_leds = pdata->num_leds;
+        } else {
+                priv = led_pwm_create_of(pdev);
+                if (!priv)
+                        return -ENODEV;
         }
-        priv->num_leds = pdata->num_leds;
 
         platform_set_drvdata(pdev, priv);
 
@@ -121,12 +186,19 @@ static int led_pwm_remove(struct platform_device *pdev)
         return 0;
 }
 
+static const struct of_device_id of_pwm_leds_match[] = {
+        { .compatible = "pwm-leds", },
+        {},
+};
+MODULE_DEVICE_TABLE(of, of_pwm_leds_match);
+
 static struct platform_driver led_pwm_driver = {
         .probe          = led_pwm_probe,
         .remove         = led_pwm_remove,
         .driver         = {
                 .name   = "leds_pwm",
                 .owner  = THIS_MODULE,
+                .of_match_table = of_match_ptr(of_pwm_leds_match),
         },
 };