Change in coreboot[master]: src/acpi/device.c: Early return in _ON if device already enabled

[Tim Van Patten (Code Review)]

Attention is currently required from: Lance Zhao, Tim Wawrzynczak.
Tim Van Patten has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/63613 )

Change subject: src/acpi/device.c: Early return in _ON if device already enabled
......................................................................

src/acpi/device.c: Early return in _ON if device already enabled

If the device has enabled `use_gpio_for_status`, then call the `_STA`
method in `_ON` to determine if the device is already enabled. If it is
already enabled, return early to skip re-enabling the device and
performing the associated sleep.

This change is necessary since the Linux kernel does not call `_STA`
before calling `_ON`.

BRANCH=None
Signed-off-by: Tim Van Patten 
BUG=b:225022810
TEST=Dump SSDT table for guybrush
Change-Id: I13aa41766555953b86eded4c72e3b317fe6db5c8
---
M src/acpi/device.c
1 file changed, 12 insertions(+), 0 deletions(-)

git pull ssh://review.coreboot.org:29418/coreboot refs/changes/13/63613/1

diff --git a/src/acpi/device.c b/src/acpi/device.c
index 1df179b..b514455 100644
--- a/src/acpi/device.c
+++ b/src/acpi/device.c
@@ -670,6 +670,18 @@

/* Method (_ON, 0, Serialized) */
    acpigen_write_method_serialized("_ON", 0);
+	/* Call _STA and early return if the device is already enabled, since the Linux
+	   kernel doesn't check the device status before calling _ON. */
+    if (params->use_gpio_for_status) {
+        /* Local0 = _STA () */
+        acpigen_write_store();
+        acpigen_emit_namestring("_STA");
+        acpigen_emit_byte(LOCAL0_OP);
+        /* If (( Local0 == ACPI_POWER_RESOURCE_STATUS_ON_OP)) */
+        acpigen_write_if_lequal_op_op(LOCAL0_OP, ACPI_POWER_RESOURCE_STATUS_ON_OP);
+        acpigen_write_return_op(ZERO_OP);
+        acpigen_write_if_end();
+    }
    if (reset_gpio)
    	acpigen_enable_tx_gpio(params->reset_gpio);
    if (enable_gpio) {