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+# SuperIO SSTD generator
+
+This page describes the common SSDT ACPI generator for SuperIO chips that can
+be found in coreboot.
+
+## Functional description
+
+In order to automatically generate ACPI functions you need to add
+a new `chip superio/common` and `device pnp xx.0 on` to your devicetree.
+
+The xx denotes the hexadecimal address of the SuperIO.
+
+Place the regular LDN pnp devices behind those two entries.
+
+The code will automatically guess the function based on the decoded
+I/O range and ISA IRQ number.
+
+## Example devicetree.cb
+
+This example is based on AST2400.
+
+```code
+# Add a "container" for proper ACPI code generation
+chip superio/common
+  device pnp 2e.0 on # just for the base device, not for the LDNs
+    chip superio/aspeed/ast2400
+      device pnp 2e.0 off  end
+      device pnp 2e.2 on # SUART1
+        io 0x60 = 0x3f8
+        irq 0x70 = 4
+      end
+      device pnp 2e.3 on # SUART2
+        io 0x60 = 0x2f8
+        irq 0x70 = 3
+      end
+      device pnp 2e.4 on # SWC
+        io 0x60 = 0xa00
+        io 0x62 = 0xa10
+        io 0x64 = 0xa20
+        io 0x66 = 0xa30
+        irq 0x70 = 0
+      end
+    end
+  end
+end
+```
+
+## 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
+   * Setting resource settings at runtime
+   * Getting resource settings at runtime
+   * Disabling LDNs at runtime