+ * Maximum brightness level
+ *
+ * Allocate and initialize device->brightness.
+ */
+
+static int
+acpi_video_init_brightness(struct acpi_video_device *device)
+{
+ union acpi_object *obj = NULL;
+ int i, max_level = 0, count = 0, level_ac_battery = 0;
+ unsigned long long level, level_old;
+ union acpi_object *o;
+ struct acpi_video_device_brightness *br = NULL;
+ int result = -EINVAL;
+
+ if (!ACPI_SUCCESS(acpi_video_device_lcd_query_levels(device, &obj))) {
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO, "Could not query available "
+ "LCD brightness level\n"));
+ goto out;
+ }
+
+ if (obj->package.count < 2)
+ goto out;
+
+ br = kzalloc(sizeof(*br), GFP_KERNEL);
+ if (!br) {
+ printk(KERN_ERR "can't allocate memory\n");
+ result = -ENOMEM;
+ goto out;
+ }
+
+ br->levels = kmalloc((obj->package.count + 2) * sizeof *(br->levels),
+ GFP_KERNEL);
+ if (!br->levels) {
+ result = -ENOMEM;
+ goto out_free;
+ }
+
+ for (i = 0; i < obj->package.count; i++) {
+ o = (union acpi_object *)&obj->package.elements[i];
+ if (o->type != ACPI_TYPE_INTEGER) {
+ printk(KERN_ERR PREFIX "Invalid data\n");
+ continue;
+ }
+ br->levels[count] = (u32) o->integer.value;
+
+ if (br->levels[count] > max_level)
+ max_level = br->levels[count];
+ count++;
+ }
+
+ /*
+ * some buggy BIOS don't export the levels
+ * when machine is on AC/Battery in _BCL package.
+ * In this case, the first two elements in _BCL packages
+ * are also supported brightness levels that OS should take care of.
+ */
+ for (i = 2; i < count; i++) {
+ if (br->levels[i] == br->levels[0])
+ level_ac_battery++;
+ if (br->levels[i] == br->levels[1])
+ level_ac_battery++;
+ }
+
+ if (level_ac_battery < 2) {
+ level_ac_battery = 2 - level_ac_battery;
+ br->flags._BCL_no_ac_battery_levels = 1;
+ for (i = (count - 1 + level_ac_battery); i >= 2; i--)
+ br->levels[i] = br->levels[i - level_ac_battery];
+ count += level_ac_battery;
+ } else if (level_ac_battery > 2)
+ ACPI_ERROR((AE_INFO, "Too many duplicates in _BCL package\n"));
+
+ /* Check if the _BCL package is in a reversed order */
+ if (max_level == br->levels[2]) {
+ br->flags._BCL_reversed = 1;
+ sort(&br->levels[2], count - 2, sizeof(br->levels[2]),
+ acpi_video_cmp_level, NULL);
+ } else if (max_level != br->levels[count - 1])
+ ACPI_ERROR((AE_INFO,
+ "Found unordered _BCL package\n"));
+
+ br->count = count;
+ device->brightness = br;
+
+ /* Check the input/output of _BQC/_BCL/_BCM */
+ if ((max_level < 100) && (max_level <= (count - 2)))
+ br->flags._BCL_use_index = 1;
+
+ /*
+ * _BCM is always consistent with _BCL,
+ * at least for all the laptops we have ever seen.
+ */
+ br->flags._BCM_use_index = br->flags._BCL_use_index;
+
+ /* _BQC uses INDEX while _BCL uses VALUE in some laptops */
+ br->curr = level = max_level;
+
+ if (!device->cap._BQC)
+ goto set_level;
+
+ result = acpi_video_device_lcd_get_level_current(device, &level_old);
+ if (result)
+ goto out_free_levels;
+
+ /*
+ * Set the level to maximum and check if _BQC uses indexed value
+ */
+ result = acpi_video_device_lcd_set_level(device, max_level);
+ if (result)
+ goto out_free_levels;
+
+ result = acpi_video_device_lcd_get_level_current(device, &level);
+ if (result)
+ goto out_free_levels;
+
+ br->flags._BQC_use_index = (level == max_level ? 0 : 1);
+
+ if (!br->flags._BQC_use_index) {
+ /*
+ * Set the backlight to the initial state.
+ * On some buggy laptops, _BQC returns an uninitialized value
+ * when invoked for the first time, i.e. level_old is invalid.
+ * set the backlight to max_level in this case
+ */
+ for (i = 2; i < br->count; i++)
+ if (level_old == br->levels[i])
+ level = level_old;
+ goto set_level;
+ }
+
+ if (br->flags._BCL_reversed)
+ level_old = (br->count - 1) - level_old;
+ level = br->levels[level_old];
+
+set_level:
+ result = acpi_video_device_lcd_set_level(device, level);
+ if (result)
+ goto out_free_levels;
+
+ ACPI_DEBUG_PRINT((ACPI_DB_INFO,
+ "found %d brightness levels\n", count - 2));
+ kfree(obj);
+ return result;
+
+out_free_levels:
+ kfree(br->levels);
+out_free:
+ kfree(br);
+out:
+ device->brightness = NULL;
+ kfree(obj);
+ return result;
+}
+
+/*
+ * Arg:
+ * device : video output device (LCD, CRT, ..)
+ *
+ * Return Value: