acpi: arm: add fw_cfg device node to dsdt

Add a fw_cfg device node to the ACPI DSDT. This is mostly
informational, as the authoritative fw_cfg MMIO region(s)
are listed in the Device Tree. However, since we are building
ACPI tables, we might as well be thorough while at it...
Signed-off-by: NGabriel Somlo <somlo@cmu.edu>
Reviewed-by: NLaszlo Ersek <lersek@redhat.com>
Tested-by: NLaszlo Ersek <lersek@redhat.com>
Reviewed-by: NMarc Marí <markmb@redhat.com>
Reviewed-by: NShannon Zhao <shannon.zhao@linaro.org>
Reviewed-by: NMichael S. Tsirkin <mst@redhat.com>
Message-id: 1455906029-25565-5-git-send-email-somlo@cmu.edu
Signed-off-by: NGerd Hoffmann <kraxel@redhat.com>

hw/arm/virt-acpi-build.c

@@ -81,6 +81,20 @@ static void acpi_dsdt_add_uart(Aml *scope, const MemMapEntry *uart_memmap,
     aml_append(scope, dev);
 }
 
+static void acpi_dsdt_add_fw_cfg(Aml *scope, const MemMapEntry *fw_cfg_memmap)
+{
+    Aml *dev = aml_device("FWCF");
+    aml_append(dev, aml_name_decl("_HID", aml_string("QEMU0002")));
+    /* device present, functioning, decoding, not shown in UI */
+    aml_append(dev, aml_name_decl("_STA", aml_int(0xB)));
+
+    Aml *crs = aml_resource_template();
+    aml_append(crs, aml_memory32_fixed(fw_cfg_memmap->base,
+                                       fw_cfg_memmap->size, AML_READ_WRITE));
+    aml_append(dev, aml_name_decl("_CRS", crs));
+    aml_append(scope, dev);
+}
+
 static void acpi_dsdt_add_flash(Aml *scope, const MemMapEntry *flash_memmap)
 {
     Aml *dev, *crs;
@@ -549,6 +563,7 @@ build_dsdt(GArray *table_data, GArray *linker, VirtGuestInfo *guest_info)
     acpi_dsdt_add_uart(scope, &memmap[VIRT_UART],
                        (irqmap[VIRT_UART] + ARM_SPI_BASE));
     acpi_dsdt_add_flash(scope, &memmap[VIRT_FLASH]);
+    acpi_dsdt_add_fw_cfg(scope, &memmap[VIRT_FW_CFG]);
     acpi_dsdt_add_virtio(scope, &memmap[VIRT_MMIO],
                     (irqmap[VIRT_MMIO] + ARM_SPI_BASE), NUM_VIRTIO_TRANSPORTS);
     acpi_dsdt_add_pci(scope, memmap, (irqmap[VIRT_PCIE] + ARM_SPI_BASE),