summaryrefslogtreecommitdiff
path: root/src/ec/google/chromeec/acpi/keyboard_backlight.asl
blob: 87be075db0884429941a187753a773f4344d6501 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
/* SPDX-License-Identifier: GPL-2.0-only */

Scope (\_SB)
{
	/*
	 * Chrome EC Keyboard Backlight interface
	 */
	Device (KBLT)
	{
		Name (_HID, "GOOG0002")
		Name (_UID, 1)

		/* Ask EC if we even have a backlight
		 * Return 0xf (present, enabled, show in UI, functioning) or 0
		 *
		 * With older EC codebases that don't support the Device
		 * Features bitfield, this reports the keyboard backlight as
		 * enabled since reads to undefined addresses in EC address
		 * space return 0xff and so KBLE will be 1.
		 */
		Method (_STA, 0, NotSerialized)
		{
			/* If query is unsupported, but this code is compiled
			 * in, assume the backlight exists physically.
			 */
			If (\_SB.PCI0.LPCB.EC0.DFUD == 1) {
				Return (0xf)
			}
			/* If EC reports that backlight exists, trust it */
			If (\_SB.PCI0.LPCB.EC0.KBLE == 1) {
				Return (0xf)
			}
			/* Otherwise: no device -> disable */
			Return (0)
		}

		/* Read current backlight value */
		Method (KBQC, 0, NotSerialized)
		{
			Return (\_SB.PCI0.LPCB.EC0.KBLV)
		}

		/* Write new backlight value */
		Method (KBCM, 1, NotSerialized)
		{
			\_SB.PCI0.LPCB.EC0.KBLV = Arg0
		}
	}
}