Re: 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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