[Qemu-devel] [PATCH v2 3/5] acpi: pc: add fw_cfg device node to ssdt

[Gabriel L. Somlo]

Add a fw_cfg device node to the ACPI SSDT. While the guest-side
BIOS can't utilize this information (since it has to access the
hard-coded fw_cfg device to extract ACPI tables to begin with),
having fw_cfg listed in ACPI will help the guest kernel keep a
more accurate inventory of in-use IO port regions.

Signed-off-by: Gabriel Somlo <address@hidden>
---
 hw/i386/acpi-build.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/hw/i386/acpi-build.c b/hw/i386/acpi-build.c
index 95e0c65..ecdb3a5 100644
--- a/hw/i386/acpi-build.c
+++ b/hw/i386/acpi-build.c
@@ -1071,6 +1071,26 @@ build_ssdt(GArray *table_data, GArray *linker,
     aml_append(scope, aml_name_decl("_S5", pkg));
     aml_append(ssdt, scope);
 
+    if (guest_info->fw_cfg) {
+        scope = aml_scope("\\_SB");
+        dev = aml_device("FWCF");
+
+        aml_append(dev, aml_name_decl("_HID", aml_string("QEMU0002")));
+
+        crs = aml_resource_template();
+        /* when using port i/o, the 8-bit data register *always* overlaps
+         * with half of the 16-bit control register. Hence, the total size
+         * of the i/o region used is FW_CFG_CTL_SIZE */
+        aml_append(crs,
+            aml_io(AML_DECODE16, FW_CFG_IO_BASE, FW_CFG_IO_BASE,
+                   0x01, FW_CFG_CTL_SIZE)
+        );
+        aml_append(dev, aml_name_decl("_CRS", crs));
+
+        aml_append(scope, dev);
+        aml_append(ssdt, scope);
+    }
+
     if (misc->applesmc_io_base) {
         scope = aml_scope("\\_SB.PCI0.ISA");
         dev = aml_device("SMC");
-- 
2.4.3