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authorHans de Goede <hdegoede@redhat.com>2014-05-21 15:39:54 +0200
committerRafael J. Wysocki <rafael.j.wysocki@intel.com>2014-05-27 01:29:01 +0200
commit3cc6919bd61315ea60baf95f3f9868aacfd1ace4 (patch)
treee50ebe95421333e2c18a146fc449ead2b84cd0f4 /drivers/video/backlight
parentbee564430feec1175ee64bcfd4913cacc519f817 (diff)
downloadlinux-stericsson-3cc6919bd61315ea60baf95f3f9868aacfd1ace4.tar.gz
backlight: Add backlight device (un)registration notification
Some firmware drivers, ie acpi-video want to get themselves out of the way (in some cases) when their also is a raw backlight device available. Due to module loading ordering being unknown, acpi-video cannot be certain that the backlight_device_registered(BACKLIGHT_RAW) it does for this is the final verdict wrt there being a BACKLIGHT_RAW device. By adding notification acpi-video can listen for backlight devices showing up after it has loaded, and unregister its backlight device if desired. Signed-off-by: Hans de Goede <hdegoede@redhat.com> Acked-by: Jingoo Han <jg1.han@samsung.com> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Diffstat (limited to 'drivers/video/backlight')
-rw-r--r--drivers/video/backlight/backlight.c40
1 files changed, 40 insertions, 0 deletions
diff --git a/drivers/video/backlight/backlight.c b/drivers/video/backlight/backlight.c
index bd2172c2d650..428089009cd5 100644
--- a/drivers/video/backlight/backlight.c
+++ b/drivers/video/backlight/backlight.c
@@ -23,6 +23,7 @@
static struct list_head backlight_dev_list;
static struct mutex backlight_dev_list_mutex;
+static struct blocking_notifier_head backlight_notifier;
static const char *const backlight_types[] = {
[BACKLIGHT_RAW] = "raw",
@@ -370,6 +371,9 @@ struct backlight_device *backlight_device_register(const char *name,
list_add(&new_bd->entry, &backlight_dev_list);
mutex_unlock(&backlight_dev_list_mutex);
+ blocking_notifier_call_chain(&backlight_notifier,
+ BACKLIGHT_REGISTERED, new_bd);
+
return new_bd;
}
EXPORT_SYMBOL(backlight_device_register);
@@ -413,6 +417,10 @@ void backlight_device_unregister(struct backlight_device *bd)
pmac_backlight = NULL;
mutex_unlock(&pmac_backlight_mutex);
#endif
+
+ blocking_notifier_call_chain(&backlight_notifier,
+ BACKLIGHT_UNREGISTERED, bd);
+
mutex_lock(&bd->ops_lock);
bd->ops = NULL;
mutex_unlock(&bd->ops_lock);
@@ -438,6 +446,36 @@ static int devm_backlight_device_match(struct device *dev, void *res,
}
/**
+ * backlight_register_notifier - get notified of backlight (un)registration
+ * @nb: notifier block with the notifier to call on backlight (un)registration
+ *
+ * @return 0 on success, otherwise a negative error code
+ *
+ * Register a notifier to get notified when backlight devices get registered
+ * or unregistered.
+ */
+int backlight_register_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_register(&backlight_notifier, nb);
+}
+EXPORT_SYMBOL(backlight_register_notifier);
+
+/**
+ * backlight_unregister_notifier - unregister a backlight notifier
+ * @nb: notifier block to unregister
+ *
+ * @return 0 on success, otherwise a negative error code
+ *
+ * Register a notifier to get notified when backlight devices get registered
+ * or unregistered.
+ */
+int backlight_unregister_notifier(struct notifier_block *nb)
+{
+ return blocking_notifier_chain_unregister(&backlight_notifier, nb);
+}
+EXPORT_SYMBOL(backlight_unregister_notifier);
+
+/**
* devm_backlight_device_register - resource managed backlight_device_register()
* @dev: the device to register
* @name: the name of the device
@@ -544,6 +582,8 @@ static int __init backlight_class_init(void)
backlight_class->pm = &backlight_class_dev_pm_ops;
INIT_LIST_HEAD(&backlight_dev_list);
mutex_init(&backlight_dev_list_mutex);
+ BLOCKING_INIT_NOTIFIER_HEAD(&backlight_notifier);
+
return 0;
}