1 files changed, 103 insertions, 33 deletions

diff --git a/arch/powerpc/platforms/powermac/backlight.c b/arch/powerpc/platforms/powermac/backlight.c
index 498b042e183..a00096b1c71 100644
--- a/arch/powerpc/platforms/powermac/backlight.c
+++ b/arch/powerpc/platforms/powermac/backlight.c
@@ -7,41 +7,66 @@
  *
  */
 
-#include <linux/config.h>
 #include <linux/kernel.h>
 #include <linux/fb.h>
 #include <linux/backlight.h>
+#include <linux/adb.h>
+#include <linux/pmu.h>
+#include <linux/atomic.h>
+#include <linux/export.h>
 #include <asm/prom.h>
 #include <asm/backlight.h>
 
 #define OLD_BACKLIGHT_MAX 15
 
-/* Protect the pmac_backlight variable */
+static void pmac_backlight_key_worker(struct work_struct *work);
+static void pmac_backlight_set_legacy_worker(struct work_struct *work);
+
+static DECLARE_WORK(pmac_backlight_key_work, pmac_backlight_key_worker);
+static DECLARE_WORK(pmac_backlight_set_legacy_work, pmac_backlight_set_legacy_worker);
+
+/* Although these variables are used in interrupt context, it makes no sense to
+ * protect them. No user is able to produce enough key events per second and
+ * notice the errors that might happen.
+ */
+static int pmac_backlight_key_queued;
+static int pmac_backlight_set_legacy_queued;
+
+/* The via-pmu code allows the backlight to be grabbed, in which case the
+ * in-kernel control of the brightness needs to be disabled. This should
+ * only be used by really old PowerBooks.
+ */
+static atomic_t kernel_backlight_disabled = ATOMIC_INIT(0);
+
+/* Protect the pmac_backlight variable below.
+   You should hold this lock when using the pmac_backlight pointer to
+   prevent its potential removal. */
 DEFINE_MUTEX(pmac_backlight_mutex);
 
 /* Main backlight storage
  *
- * Backlight drivers in this variable are required to have the "props"
+ * Backlight drivers in this variable are required to have the "ops"
  * attribute set and to have an update_status function.
  *
  * We can only store one backlight here, but since Apple laptops have only one
  * internal display, it doesn't matter. Other backlight drivers can be used
  * independently.
  *
- * Lock ordering:
- * pmac_backlight_mutex (global, main backlight)
- *   pmac_backlight->sem (backlight class)
  */
 struct backlight_device *pmac_backlight;
 
 int pmac_has_backlight_type(const char *type)
 {
-	struct device_node* bk_node = find_devices("backlight");
+	struct device_node* bk_node = of_find_node_by_name(NULL, "backlight");
 
 	if (bk_node) {
-		char *prop = get_property(bk_node, "backlight-control", NULL);
-		if (prop && strncmp(prop, type, strlen(type)) == 0)
+		const char *prop = of_get_property(bk_node,
+				"backlight-control", NULL);
+		if (prop && strncmp(prop, type, strlen(type)) == 0) {
+			of_node_put(bk_node);
 			return 1;
+		}
+		of_node_put(bk_node);
 	}
 
 	return 0;
@@ -72,18 +97,21 @@ int pmac_backlight_curve_lookup(struct fb_info *info, int value)
 	return level;
 }
 
-static void pmac_backlight_key(int direction)
+static void pmac_backlight_key_worker(struct work_struct *work)
 {
+	if (atomic_read(&kernel_backlight_disabled))
+		return;
+
 	mutex_lock(&pmac_backlight_mutex);
 	if (pmac_backlight) {
 		struct backlight_properties *props;
 		int brightness;
 
-		down(&pmac_backlight->sem);
-		props = pmac_backlight->props;
+		props = &pmac_backlight->props;
 
 		brightness = props->brightness +
-			((direction?-1:1) * (props->max_brightness / 15));
+			((pmac_backlight_key_queued?-1:1) *
+			 (props->max_brightness / 15));
 
 		if (brightness < 0)
 			brightness = 0;
@@ -91,24 +119,25 @@ static void pmac_backlight_key(int direction)
 			brightness = props->max_brightness;
 
 		props->brightness = brightness;
-		props->update_status(pmac_backlight);
-
-		up(&pmac_backlight->sem);
+		backlight_update_status(pmac_backlight);
 	}
 	mutex_unlock(&pmac_backlight_mutex);
 }
 
-void pmac_backlight_key_up()
+/* This function is called in interrupt context */
+void pmac_backlight_key(int direction)
 {
-	pmac_backlight_key(0);
+	if (atomic_read(&kernel_backlight_disabled))
+		return;
+
+	/* we can receive multiple interrupts here, but the scheduled work
+	 * will run only once, with the last value
+	 */
+	pmac_backlight_key_queued = direction;
+	schedule_work(&pmac_backlight_key_work);
 }
 
-void pmac_backlight_key_down()
-{
-	pmac_backlight_key(1);
-}
-
-int pmac_backlight_set_legacy_brightness(int brightness)
+static int __pmac_backlight_set_legacy_brightness(int brightness)
 {
 	int error = -ENXIO;
 
@@ -116,12 +145,17 @@ int pmac_backlight_set_legacy_brightness(int brightness)
 	if (pmac_backlight) {
 		struct backlight_properties *props;
 
-		down(&pmac_backlight->sem);
-		props = pmac_backlight->props;
+		props = &pmac_backlight->props;
 		props->brightness = brightness *
-			props->max_brightness / OLD_BACKLIGHT_MAX;
-		props->update_status(pmac_backlight);
-		up(&pmac_backlight->sem);
+			(props->max_brightness + 1) /
+			(OLD_BACKLIGHT_MAX + 1);
+
+		if (props->brightness > props->max_brightness)
+			props->brightness = props->max_brightness;
+		else if (props->brightness < 0)
+			props->brightness = 0;
+
+		backlight_update_status(pmac_backlight);
 
 		error = 0;
 	}
@@ -130,6 +164,28 @@ int pmac_backlight_set_legacy_brightness(int brightness)
 	return error;
 }
 
+static void pmac_backlight_set_legacy_worker(struct work_struct *work)
+{
+	if (atomic_read(&kernel_backlight_disabled))
+		return;
+
+	__pmac_backlight_set_legacy_brightness(pmac_backlight_set_legacy_queued);
+}
+
+/* This function is called in interrupt context */
+void pmac_backlight_set_legacy_brightness_pmu(int brightness) {
+	if (atomic_read(&kernel_backlight_disabled))
+		return;
+
+	pmac_backlight_set_legacy_queued = brightness;
+	schedule_work(&pmac_backlight_set_legacy_work);
+}
+
+int pmac_backlight_set_legacy_brightness(int brightness)
+{
+	return __pmac_backlight_set_legacy_brightness(brightness);
+}
+
 int pmac_backlight_get_legacy_brightness()
 {
 	int result = -ENXIO;
@@ -138,13 +194,27 @@ int pmac_backlight_get_legacy_brightness()
 	if (pmac_backlight) {
 		struct backlight_properties *props;
 
-		down(&pmac_backlight->sem);
-		props = pmac_backlight->props;
+		props = &pmac_backlight->props;
+
 		result = props->brightness *
-			OLD_BACKLIGHT_MAX / props->max_brightness;
-		up(&pmac_backlight->sem);
+			(OLD_BACKLIGHT_MAX + 1) /
+			(props->max_brightness + 1);
 	}
 	mutex_unlock(&pmac_backlight_mutex);
 
 	return result;
 }
+
+void pmac_backlight_disable()
+{
+	atomic_inc(&kernel_backlight_disabled);
+}
+
+void pmac_backlight_enable()
+{
+	atomic_dec(&kernel_backlight_disabled);
+}
+
+EXPORT_SYMBOL_GPL(pmac_backlight);
+EXPORT_SYMBOL_GPL(pmac_backlight_mutex);
+EXPORT_SYMBOL_GPL(pmac_has_backlight_type);