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SubjectRe: Git backlight subsystem tree

> On Thu, Feb 08, 2007 at 06:32:02PM +0000, James Simmons wrote:
> > On Thu, 8 Feb 2007, Richard Purdie wrote:
> >
> > > On Thu, 2007-02-08 at 15:28 +0000, James Simmons wrote:
> > > > I have some patches that move the backlight away from using the class
> > > > stuff. The only problem is the patch requires all backlight devices
> > > > to be linked to a real struct device. Right now the acpi backligths are
> > > > not.
> > >
> > > Why would you want to do that?
> > >
> > > The whole point of having this is so that backlights appear as a
> > > standard interface under /sys/class/backlight.
> > >
> > > An example of why standardised interfaces are good would be someone
> > > writing an applet for a handheld to control the backlight brightness.
> > > With the class in place, the applet can easily work with any backlight.
> > > Without it, it has to be written for each backlight.
> > >
> > > So this is a very strong NAK but I'm curious why you'd want to do it...
> >
> > I CC Greg to explain. The backlight class didn't go away. The way it is
> > handled is different.
>
> Have a pointer to the patch so I can help explain better?
>
> As a short summary, 'struct class_device' is going away. Using a
> 'struct device' in its place is what the conversion should have just
> done, no functionality change otherwise.

diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index 9601bfe..b56fc33 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -14,6 +14,8 @@
#include <linux/err.h>
#include <linux/fb.h>

+struct class *backlight_class;
+static int index;

#if defined(CONFIG_FB) || (defined(CONFIG_FB_MODULE) && \
defined(CONFIG_BACKLIGHT_CLASS_DEVICE_MODULE))
@@ -67,10 +69,11 @@ static inline void backlight_unregister_fb(struct backlight_device *bd)
}
#endif /* CONFIG_FB */

-static ssize_t backlight_show_power(struct class_device *cdev, char *buf)
+static ssize_t backlight_show_power(struct device *dev, struct device_attribute *attr,
+ char *buf)
{
int rc = -ENXIO;
- struct backlight_device *bd = to_backlight_device(cdev);
+ struct backlight_device *bd = dev_get_drvdata(dev);

down(&bd->sem);
if (likely(bd->props))
@@ -80,11 +83,12 @@ static ssize_t backlight_show_power(struct class_device *cdev, char *buf)
return rc;
}

-static ssize_t backlight_store_power(struct class_device *cdev, const char *buf, size_t count)
+static ssize_t backlight_store_power(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
{
int rc = -ENXIO;
char *endp;
- struct backlight_device *bd = to_backlight_device(cdev);
+ struct backlight_device *bd = dev_get_drvdata(dev);
int power = simple_strtoul(buf, &endp, 0);
size_t size = endp - buf;

@@ -106,10 +110,11 @@ static ssize_t backlight_store_power(struct class_device *cdev, const char *buf,
return rc;
}

-static ssize_t backlight_show_brightness(struct class_device *cdev, char *buf)
+static ssize_t backlight_show_brightness(struct device *dev, struct device_attribute *attr,
+ char *buf)
{
int rc = -ENXIO;
- struct backlight_device *bd = to_backlight_device(cdev);
+ struct backlight_device *bd = dev_get_drvdata(dev);

down(&bd->sem);
if (likely(bd->props))
@@ -119,11 +124,12 @@ static ssize_t backlight_show_brightness(struct class_device *cdev, char *buf)
return rc;
}

-static ssize_t backlight_store_brightness(struct class_device *cdev, const char *buf, size_t count)
+static ssize_t backlight_store_brightness(struct device *dev, struct device_attribute *attr,
+ const char *buf, size_t count)
{
int rc = -ENXIO;
char *endp;
- struct backlight_device *bd = to_backlight_device(cdev);
+ struct backlight_device *bd = dev_get_drvdata(dev);
int brightness = simple_strtoul(buf, &endp, 0);
size_t size = endp - buf;

@@ -150,10 +156,11 @@ static ssize_t backlight_store_brightness(struct class_device *cdev, const char
return rc;
}

-static ssize_t backlight_show_max_brightness(struct class_device *cdev, char *buf)
+static ssize_t backlight_show_max_brightness(struct device *dev, struct device_attribute *attr,
+ char *buf)
{
int rc = -ENXIO;
- struct backlight_device *bd = to_backlight_device(cdev);
+ struct backlight_device *bd = dev_get_drvdata(dev);

down(&bd->sem);
if (likely(bd->props))
@@ -163,11 +170,11 @@ static ssize_t backlight_show_max_brightness(struct class_device *cdev, char *bu
return rc;
}

-static ssize_t backlight_show_actual_brightness(struct class_device *cdev,
+static ssize_t backlight_show_actual_brightness(struct device *dev, struct device_attribute *attr,
char *buf)
{
+ struct backlight_device *bd = dev_get_drvdata(dev);
int rc = -ENXIO;
- struct backlight_device *bd = to_backlight_device(cdev);

down(&bd->sem);
if (likely(bd->props && bd->props->get_brightness))
@@ -177,31 +184,12 @@ static ssize_t backlight_show_actual_brightness(struct class_device *cdev,
return rc;
}

-static void backlight_class_release(struct class_device *dev)
-{
- struct backlight_device *bd = to_backlight_device(dev);
- kfree(bd);
-}
-
-static struct class backlight_class = {
- .name = "backlight",
- .release = backlight_class_release,
-};
-
-#define DECLARE_ATTR(_name,_mode,_show,_store) \
-{ \
- .attr = { .name = __stringify(_name), .mode = _mode, .owner = THIS_MODULE }, \
- .show = _show, \
- .store = _store, \
-}
-
-static const struct class_device_attribute bl_class_device_attributes[] = {
- DECLARE_ATTR(power, 0644, backlight_show_power, backlight_store_power),
- DECLARE_ATTR(brightness, 0644, backlight_show_brightness,
- backlight_store_brightness),
- DECLARE_ATTR(actual_brightness, 0444, backlight_show_actual_brightness,
- NULL),
- DECLARE_ATTR(max_brightness, 0444, backlight_show_max_brightness, NULL),
+static struct device_attribute bl_class_device_attributes[] = {
+ __ATTR(power, S_IRUGO | S_IWUSR, backlight_show_power, backlight_store_power),
+ __ATTR(brightness, S_IRUGO | S_IWUSR, backlight_show_brightness,
+ backlight_store_brightness),
+ __ATTR(actual_brightness, S_IRUGO, backlight_show_actual_brightness, NULL),
+ __ATTR(max_brightness, S_IRUGO, backlight_show_max_brightness, NULL),
};

/**
@@ -217,12 +205,11 @@ static const struct class_device_attribute bl_class_device_attributes[] = {
* ERR_PTR() or a pointer to the newly allocated device.
*/
struct backlight_device *backlight_device_register(const char *name,
- struct device *dev,
- void *devdata,
+ struct device *parent, void *devdata,
struct backlight_properties *bp)
{
- int i, rc;
struct backlight_device *new_bd;
+ int rc;

pr_debug("backlight_device_alloc: name=%s\n", name);

@@ -230,37 +217,21 @@ struct backlight_device *backlight_device_register(const char *name,
if (unlikely(!new_bd))
return ERR_PTR(-ENOMEM);

+ new_bd->device = device_create(backlight_class, parent, 0,
+ name, index++);
+ if (IS_ERR(new_bd->device)) {
+ new_bd->device = NULL;
+ return ERR_PTR(-EINVAL);
+ }
+
init_MUTEX(&new_bd->sem);
+ dev_set_drvdata(new_bd->device, devdata);
new_bd->props = bp;
- memset(&new_bd->class_dev, 0, sizeof(new_bd->class_dev));
- new_bd->class_dev.class = &backlight_class;
- new_bd->class_dev.dev = dev;
- strlcpy(new_bd->class_dev.class_id, name, KOBJ_NAME_LEN);
- class_set_devdata(&new_bd->class_dev, devdata);

- rc = class_device_register(&new_bd->class_dev);
+ rc = backlight_register_fb(new_bd);
if (unlikely(rc)) {
-error: kfree(new_bd);
- return ERR_PTR(rc);
- }

- rc = backlight_register_fb(new_bd);
- if (unlikely(rc))
- goto error;
-
- for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++) {
- rc = class_device_create_file(&new_bd->class_dev,
- &bl_class_device_attributes[i]);
- if (unlikely(rc)) {
- while (--i >= 0)
- class_device_remove_file(&new_bd->class_dev,
- &bl_class_device_attributes[i]);
- class_device_unregister(&new_bd->class_dev);
- /* No need to kfree(new_bd) since release() method was called */
- return ERR_PTR(rc);
- }
}
-
return new_bd;
}
EXPORT_SYMBOL(backlight_device_register);
@@ -273,35 +244,36 @@ EXPORT_SYMBOL(backlight_device_register);
*/
void backlight_device_unregister(struct backlight_device *bd)
{
- int i;
-
if (!bd)
return;

- pr_debug("backlight_device_unregister: name=%s\n", bd->class_dev.class_id);
-
- for (i = 0; i < ARRAY_SIZE(bl_class_device_attributes); i++)
- class_device_remove_file(&bd->class_dev,
- &bl_class_device_attributes[i]);
+ pr_debug("backlight_device_unregister\n");

down(&bd->sem);
bd->props = NULL;
up(&bd->sem);

backlight_unregister_fb(bd);
-
- class_device_unregister(&bd->class_dev);
+ dev_set_drvdata(bd->device, NULL);
+ device_unregister(bd->device);
}
EXPORT_SYMBOL(backlight_device_unregister);

static void __exit backlight_class_exit(void)
{
- class_unregister(&backlight_class);
+ class_destroy(backlight_class);
}

static int __init backlight_class_init(void)
{
- return class_register(&backlight_class);
+ backlight_class = class_create(THIS_MODULE, "backlight");
+ if (IS_ERR(backlight_class)) {
+ printk(KERN_WARNING "Unable to create backlight class; errno = %ld\n",
+ PTR_ERR(backlight_class));
+ backlight_class = NULL;
+ } else
+ backlight_class->dev_attrs = bl_class_device_attributes;
+ return 0;
}

/*
diff --git a/include/linux/backlight.h b/include/linux/backlight.h
index a5cf1be..d593266 100644
--- a/include/linux/backlight.h
+++ b/include/linux/backlight.h
@@ -49,8 +49,10 @@ struct backlight_device {
struct backlight_properties *props;
/* The framebuffer notifier block */
struct notifier_block fb_notif;
- /* The class device structure */
- struct class_device class_dev;
+ /* Parent device */
+ struct device *parent;
+ /* The device structure */
+ struct device *device;
};

extern struct backlight_device *backlight_device_register(const char *name,
-
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