[PATCH 1/3] pwm-backlight: add subdriver mechanism

@@ -29,6 +29,10 @@ obj-$(CONFIG_BACKLIGHT_LP855X)	+= lp855x_bl.o
 obj-$(CONFIG_BACKLIGHT_OMAP1)	+= omap1_bl.o
 obj-$(CONFIG_BACKLIGHT_PANDORA)	+= pandora_bl.o
 obj-$(CONFIG_BACKLIGHT_CARILLO_RANCH) += cr_bllcd.o
+# pwm-backlight subdrivers must be listed *before* pwm_bl.o.
+# Link order is important as subdrivers must register themselves
+# before pwm-backlight's probe function can be called.
+obj-$(CONFIG_BACKLIGHT_PWM_TEGRA) += pwm_bl_tegra.o
 obj-$(CONFIG_BACKLIGHT_PWM)	+= pwm_bl.o
 obj-$(CONFIG_BACKLIGHT_DA903X)	+= da903x_bl.o
 obj-$(CONFIG_BACKLIGHT_DA9052)	+= da9052_bl.o

@@ -22,6 +22,7 @@
 #include <linux/slab.h>
 
 struct pwm_bl_data {
+	void			*subdriver_data;
 	struct pwm_device	*pwm;
 	struct device		*dev;
 	unsigned int		period;

@@ -35,6 +36,54 @@ struct pwm_bl_data {
 	void			(*exit)(struct device *);
 };
 
+static DEFINE_MUTEX(pwm_backlight_subdrivers_mutex);
+static LIST_HEAD(pwm_backlight_subdrivers);
+
+void pwm_backlight_add_subdriver(struct pwm_backlight_subdriver *driver)
+{
+	mutex_lock(&pwm_backlight_subdrivers_mutex);
+	list_add(&driver->list, &pwm_backlight_subdrivers);
+	mutex_unlock(&pwm_backlight_subdrivers_mutex);
+}
+EXPORT_SYMBOL(pwm_backlight_add_subdriver);
+
+void pwm_backlight_remove_subdriver(struct pwm_backlight_subdriver *driver)
+{
+	mutex_lock(&pwm_backlight_subdrivers_mutex);
+	list_del(&driver->list);
+	mutex_unlock(&pwm_backlight_subdrivers_mutex);
+}
+EXPORT_SYMBOL(pwm_backlight_remove_subdriver);
+
+/**
+ * pwm_backlight_set_subdriver_data - set subdriver data
+ * @dev: backlight device which data is to be set
+ * @data: subdriver data
+ *
+ * This function can be called *only* in the init() hook of the subdriver. The
+ * data will be temporarily set as driver data before being retrieved by
+ * the probe() function and moved to its final place.
+ */
+void pwm_backlight_set_subdriver_data(struct device *dev, void *data)
+{
+	dev_set_drvdata(dev, data);
+}
+EXPORT_SYMBOL(pwm_backlight_set_subdriver_data);
+
+/**
+ * pwm_backlight_get_subdriver_data - retrieve subdriver data
+ * @dev: backlight device to get subdriver data of
+ *
+ * This function can be called in any subdriver hook, excepted init().
+ */
+void *pwm_backlight_get_subdriver_data(struct device *dev)
+{
+	struct backlight_device *bl = dev_get_drvdata(dev);
+	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);
+	return pb->subdriver_data;
+}
+EXPORT_SYMBOL(pwm_backlight_get_subdriver_data);
+
 static int pwm_backlight_update_status(struct backlight_device *bl)
 {
 	struct pwm_bl_data *pb = dev_get_drvdata(&bl->dev);

@@ -98,6 +147,7 @@ static const struct backlight_ops pwm_backlight_ops = {
 static int pwm_backlight_parse_dt(struct device *dev,
 				  struct platform_pwm_backlight_data *data)
 {
+	struct pwm_backlight_subdriver *subdriver;
 	struct device_node *node = dev->of_node;
 	struct property *prop;
 	int length;

@@ -150,6 +200,17 @@ static int pwm_backlight_parse_dt(struct device *dev,
 	 *       backlight power. Support for specifying these needs to be
 	 *       added.
 	 */
+	mutex_lock(&pwm_backlight_subdrivers_mutex);
+	list_for_each_entry(subdriver, &pwm_backlight_subdrivers, list)
+		if (of_device_is_compatible(node, subdriver->name)) {
+			data->init = subdriver->init;
+			data->exit = subdriver->exit;
+			data->notify = subdriver->notify;
+			data->notify_after = subdriver->notify_after;
+			data->check_fb = subdriver->check_fb;
+			break;
+		}
+	mutex_unlock(&pwm_backlight_subdrivers_mutex);
 
 	return 0;
 }

@@ -201,6 +262,9 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 		goto err_alloc;
 	}
 
+	/* if the init function set subdriver data, move it to correct place */
+	pb->subdriver_data = dev_get_drvdata(&pdev->dev);
+
 	if (data->levels) {
 		max = data->levels[data->max_brightness];
 		pb->levels = data->levels;

@@ -249,10 +313,11 @@ static int pwm_backlight_probe(struct platform_device *pdev)
 		goto err_alloc;
 	}
 
+	platform_set_drvdata(pdev, bl);
+
 	bl->props.brightness = data->dft_brightness;
 	backlight_update_status(bl);
 
-	platform_set_drvdata(pdev, bl);
 	return 0;
 
 err_alloc:

@@ -20,4 +20,19 @@ struct platform_pwm_backlight_data {
 	int (*check_fb)(struct device *dev, struct fb_info *info);
 };
 
+struct pwm_backlight_subdriver {
+	struct list_head list;
+	const char *name;
+	int (*init)(struct device *dev);
+	int (*notify)(struct device *dev, int brightness);
+	void (*notify_after)(struct device *dev, int brightness);
+	void (*exit)(struct device *dev);
+	int (*check_fb)(struct device *dev, struct fb_info *info);
+};
+
+void pwm_backlight_add_subdriver(struct pwm_backlight_subdriver *driver);
+void pwm_backlight_remove_subdriver(struct pwm_backlight_subdriver *driver);
+
+void pwm_backlight_set_subdriver_data(struct device *dev, void *data);
+void *pwm_backlight_get_subdriver_data(struct device *dev);
 #endif