hw/pci-host/gpex-acpi: Add support for dsdt construction for pxb-cxl

This adds code to instantiate the slightly extended ACPI root port
description in DSDT as per the CXL 2.0 specification.

Basically a cut and paste job from the i386/pc code.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Ben Widawsky <ben.widawsky@intel.com>
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Message-Id: <20220429144110.25167-30-Jonathan.Cameron@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>

hw/arm/Kconfig

@@ -29,6 +29,7 @@ config ARM_VIRT
     select ACPI_APEI
     select ACPI_VIOT
     select VIRTIO_MEM_SUPPORTED
+    select ACPI_CXL
 
 config CHEETAH
     bool

hw/pci-host/gpex-acpi.c

@@ -5,6 +5,7 @@
 #include "hw/pci/pci_bus.h"
 #include "hw/pci/pci_bridge.h"
 #include "hw/pci/pcie_host.h"
+#include "hw/acpi/cxl.h"
 
 static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
 {
@@ -139,6 +140,7 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
         QLIST_FOREACH(bus, &bus->child, sibling) {
             uint8_t bus_num = pci_bus_num(bus);
             uint8_t numa_node = pci_bus_numa_node(bus);
+            bool is_cxl = pci_bus_is_cxl(bus);
 
             if (!pci_bus_is_root(bus)) {
                 continue;
@@ -154,8 +156,16 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
             }
 
             dev = aml_device("PC%.02X", bus_num);
-            aml_append(dev, aml_name_decl("_HID", aml_string("PNP0A08")));
-            aml_append(dev, aml_name_decl("_CID", aml_string("PNP0A03")));
+            if (is_cxl) {
+                struct Aml *pkg = aml_package(2);
+                aml_append(dev, aml_name_decl("_HID", aml_string("ACPI0016")));
+                aml_append(pkg, aml_eisaid("PNP0A08"));
+                aml_append(pkg, aml_eisaid("PNP0A03"));
+                aml_append(dev, aml_name_decl("_CID", pkg));
+            } else {
+                aml_append(dev, aml_name_decl("_HID", aml_string("PNP0A08")));
+                aml_append(dev, aml_name_decl("_CID", aml_string("PNP0A03")));
+            }
             aml_append(dev, aml_name_decl("_BBN", aml_int(bus_num)));
             aml_append(dev, aml_name_decl("_UID", aml_int(bus_num)));
             aml_append(dev, aml_name_decl("_STR", aml_unicode("pxb Device")));
@@ -175,7 +185,11 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
                             cfg->pio.base, 0, 0, 0);
             aml_append(dev, aml_name_decl("_CRS", crs));
 
-            acpi_dsdt_add_pci_osc(dev);
+            if (is_cxl) {
+                build_cxl_osc_method(dev);
+            } else {
+                acpi_dsdt_add_pci_osc(dev);
+            }
 
             aml_append(scope, dev);
         }