[Qemu-devel] [RFC PATCH 3/3] acpi: arm: add fw_cfg device node to dsdt

["Gabriel L. Somlo" <somlo@cmu.edu>]

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: Gabriel Somlo <somlo@cmu.edu>
---

I used surrounding examples to create acpi_dsdt_add_fw_cfg(), and
noticed that none add a _STA method, and many include a 0 _UID even
for nodes with a single instance. I wonder whether 1. I really need
the _UID, and 2. why would we be OK not including a _STA method ?

Is the #2 answer "because no exisging arm OSPM does in fact check,
and/or care about the absence of _STA" ? :)

Thanks,
 --Gabriel

 hw/arm/virt-acpi-build.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 9088248..150c9f9 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -110,6 +110,23 @@ static void acpi_dsdt_add_rtc(Aml *scope, const MemMapEntry *rtc_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("FWCF0001")));
+
+    /* FIXME: is this necessary ? */
+    aml_append(dev, aml_name_decl("_UID", aml_int(0)));
+    /* FIXME: why doesn't a _STA get added to any other node ? */
+    aml_append(dev, aml_name_decl("_STA", aml_int(0x0B)));
+
+    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;
@@ -519,6 +536,7 @@ build_dsdt(GArray *table_data, GArray *linker, VirtGuestInfo *guest_info)
                        (irqmap[VIRT_UART] + ARM_SPI_BASE));
     acpi_dsdt_add_rtc(scope, &memmap[VIRT_RTC],
                       (irqmap[VIRT_RTC] + ARM_SPI_BASE));
+    acpi_dsdt_add_fw_cfg(scope, &memmap[VIRT_FW_CFG]);
     acpi_dsdt_add_flash(scope, &memmap[VIRT_FLASH]);
     acpi_dsdt_add_virtio(scope, &memmap[VIRT_MMIO],
                     (irqmap[VIRT_MMIO] + ARM_SPI_BASE), NUM_VIRTIO_TRANSPORTS);
-- 
2.4.3