src/ec/google/chromeec/acpi/keyboard_backlight.asl

   1 /* SPDX-License-Identifier: GPL-2.0-only */
   2
   3 Scope (\_SB)
   4 {
   5         /*
   6          * Chrome EC Keyboard Backlight interface
   7          */
   8         Device (KBLT)
   9         {
  10                 Name (_HID, "GOOG0002")
  11                 Name (_UID, 1)
  12
  13                 /* Ask EC if we even have a backlight
  14                  * Return 0xf (present, enabled, show in UI, functioning) or 0
  15                  *
  16                  * With older EC codebases that don't support the Device
  17                  * Features bitfield, this reports the keyboard backlight as
  18                  * enabled since reads to undefined addresses in EC address
  19                  * space return 0xff and so KBLE will be 1.
  20                  */
  21                 Method (_STA, 0, NotSerialized)
  22                 {
  23                         /* If query is unsupported, but this code is compiled
  24                          * in, assume the backlight exists physically.
  25                          */
  26                         If (\_SB.PCI0.LPCB.EC0.DFUD == 1) {
  27                                 Return (0xf)
  28                         }
  29                         /* If EC reports that backlight exists, trust it */
  30                         If (\_SB.PCI0.LPCB.EC0.KBLE == 1) {
  31                                 Return (0xf)
  32                         }
  33                         /* Otherwise: no device -> disable */
  34                         Return (0)
  35                 }
  36
  37                 /* Read current backlight value */
  38                 Method (KBQC, 0, NotSerialized)
  39                 {
  40                         Return (\_SB.PCI0.LPCB.EC0.KBLV)
  41                 }
  42
  43                 /* Write new backlight value */
  44                 Method (KBCM, 1, NotSerialized)
  45                 {
  46                         \_SB.PCI0.LPCB.EC0.KBLV = Arg0
  47                 }
  48         }
  49 }