superio/common: Add more ACPI methods

* Make use of introduced SSDT config mode access
* Make use of introduced SSDT mutex
* Provide ACPI functions to safely access SIO config space
* Implement method to query LDN enable state
* Implement method to set LDN enable state
* Use introduced functions to implement _DIS and _STA in the device
* Update documentation

Tested on Aspeed AST2500 and Linux 5.2.
Manually verified ACPI code that generates no errors in Linux.

Change-Id: I520b29de925f368cd71ff8f1f58d2d57d72eff8d
Signed-off-by: Patrick Rudolph <patrick.rudolph@9elements.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/37640
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Felix Held <felix-coreboot@felixheld.de>

1 files changed, 25 insertions, 4 deletions

diff --git a/Documentation/superio/common/ssdt.md b/Documentation/superio/common/ssdt.md
index f2bb3346a00e..2f4049ef1255 100644
--- a/Documentation/superio/common/ssdt.md
+++ b/Documentation/superio/common/ssdt.md
@@ -45,12 +45,33 @@ chip superio/common
 end
 ```
 
+## Automatically generated methods
+
+The following methods are generated for each SuperIO:
+## AMTX()
+Acquire the global mutex and enter config mode.
+It's called this at the begining of an atomic operation to make sure
+no other ACPI code messes with the config space while working on it.
+
+## RMTX()
+Exit config mode and release the global mutex.
+It's called at the end of an atomic operation.
+
+## SLDN(Arg0)
+Selects the (virtual) LDN given as Arg0.
+This method isn't guarded with the global mutex.
+
+## DLDN(Arg0)
+Disables the (virtual) LDN given as Arg0.
+This method aquires the global mutex.
+
+## QLDN(Arg0)
+Queries the state of the (virtual) LDN given as Arg0.
+This method quires the global mutex.
+
 ## TODO
 
 1) Add ACPI HIDs to every SuperIO driver
-2) Don't guess ACPI HID of LDNs if it's known
-3) Add "enter config" and "exit config" bytes
-4) Generate support methods that allow
+2) Generate support methods that allow
    * Setting resource settings at runtime
    * Getting resource settings at runtime
-   * Disabling LDNs at runtime