ACPI: thinkpad-acpi: allow use of CMOS NVRAM for brightness control
It appears that Lenovo decided to break the EC brightness control interface
in a weird way in their latest BIOSes. Fortunately, the old CMOS NVRAM
interface works just fine in such BIOSes.
Add a module parameter that allows the user to select which strategy to use
for brightness control: EC, NVRAM, or both. By default, do both (which is
the way thinkpad-acpi used to work until now) on IBM ThinkPads, and use
NVRAM only on Lenovo ThinkPads.
Signed-off-by: Henrique de Moraes Holschuh <hmh@hmh.eng.br>
Signed-off-by: Len Brown <len.brown@intel.com>
diff --git a/drivers/misc/thinkpad_acpi.h b/drivers/misc/thinkpad_acpi.h
index 09b2282..b7a4a88 100644
--- a/drivers/misc/thinkpad_acpi.h
+++ b/drivers/misc/thinkpad_acpi.h
@@ -32,6 +32,7 @@
#include <linux/list.h>
#include <linux/mutex.h>
+#include <linux/nvram.h>
#include <linux/proc_fs.h>
#include <linux/sysfs.h>
#include <linux/backlight.h>
@@ -80,6 +81,11 @@
#define TP_CMOS_BRIGHTNESS_UP 4
#define TP_CMOS_BRIGHTNESS_DOWN 5
+/* ThinkPad CMOS NVRAM constants */
+#define TP_NVRAM_ADDR_BRIGHTNESS 0x5e
+#define TP_NVRAM_MASK_LEVEL_BRIGHTNESS 0x07
+#define TP_NVRAM_POS_LEVEL_BRIGHTNESS 0
+
#define onoff(status,bit) ((status) & (1 << (bit)) ? "on" : "off")
#define enabled(status,bit) ((status) & (1 << (bit)) ? "enabled" : "disabled")
#define strlencmp(a,b) (strncmp((a), (b), strlen(b)))
@@ -323,6 +329,7 @@
static struct backlight_device *ibm_backlight_device;
static int brightness_offset = 0x31;
+static int brightness_mode;
static int brightness_init(struct ibm_init_struct *iibm);
static void brightness_exit(void);