+#ifdef CONFIG_FB_BACKLIGHT
+static ssize_t store_bl_curve(struct class_device *class_device,
+ const char *buf, size_t count)
+{
+ struct fb_info *fb_info = class_get_devdata(class_device);
+ u8 tmp_curve[FB_BACKLIGHT_LEVELS];
+ unsigned int i;
+
+ /* Some drivers don't use framebuffer_alloc(), but those also
+ * don't have backlights.
+ */
+ if (!fb_info || !fb_info->bl_dev)
+ return -ENODEV;
+
+ if (count != (FB_BACKLIGHT_LEVELS / 8 * 24))
+ return -EINVAL;
+
+ for (i = 0; i < (FB_BACKLIGHT_LEVELS / 8); ++i)
+ if (sscanf(&buf[i * 24],
+ "%2hhx %2hhx %2hhx %2hhx %2hhx %2hhx %2hhx %2hhx\n",
+ &tmp_curve[i * 8 + 0],
+ &tmp_curve[i * 8 + 1],
+ &tmp_curve[i * 8 + 2],
+ &tmp_curve[i * 8 + 3],
+ &tmp_curve[i * 8 + 4],
+ &tmp_curve[i * 8 + 5],
+ &tmp_curve[i * 8 + 6],
+ &tmp_curve[i * 8 + 7]) != 8)
+ return -EINVAL;
+
+ /* If there has been an error in the input data, we won't
+ * reach this loop.
+ */
+ mutex_lock(&fb_info->bl_mutex);
+ for (i = 0; i < FB_BACKLIGHT_LEVELS; ++i)
+ fb_info->bl_curve[i] = tmp_curve[i];
+ mutex_unlock(&fb_info->bl_mutex);
+
+ return count;
+}
+
+static ssize_t show_bl_curve(struct class_device *class_device, char *buf)
+{
+ struct fb_info *fb_info = class_get_devdata(class_device);
+ ssize_t len = 0;
+ unsigned int i;
+
+ /* Some drivers don't use framebuffer_alloc(), but those also
+ * don't have backlights.
+ */
+ if (!fb_info || !fb_info->bl_dev)
+ return -ENODEV;
+
+ mutex_lock(&fb_info->bl_mutex);
+ for (i = 0; i < FB_BACKLIGHT_LEVELS; i += 8)
+ len += snprintf(&buf[len], PAGE_SIZE,
+ "%02x %02x %02x %02x %02x %02x %02x %02x\n",
+ fb_info->bl_curve[i + 0],
+ fb_info->bl_curve[i + 1],
+ fb_info->bl_curve[i + 2],
+ fb_info->bl_curve[i + 3],
+ fb_info->bl_curve[i + 4],
+ fb_info->bl_curve[i + 5],
+ fb_info->bl_curve[i + 6],
+ fb_info->bl_curve[i + 7]);
+ mutex_unlock(&fb_info->bl_mutex);
+
+ return len;
+}
+#endif
+