[PATCH v2 4/9] acpi/gpex: Create PCI link devices outside PCI root bridge

[Sunil V L <sunilvl@ventanamicro.com>]

Currently, PCI link devices (PNP0C0F) are always created within the
scope of the PCI root bridge. However, RISC-V needs these link devices
to be created outside to ensure the probing order in the OS. This
matches the example given in the ACPI specification [1] as well. Hence,
create these link devices directly under _SB instead of under the PCI
root bridge.

To keep these link device names unique for multiple PCI bridges, change
the device name from GSIx to LXXY format where XX is the PCI bus number
and Y is the INTx.

GPEX is currently used by riscv, aarch64/virt and x86/microvm machines.
So, this change will alter the DSDT for those systems.

[1] - ACPI 5.1: 6.2.13.1 Example: Using _PRT to Describe PCI IRQ Routing

Signed-off-by: Sunil V L <sunilvl@ventanamicro.com>
---
 hw/pci-host/gpex-acpi.c | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/hw/pci-host/gpex-acpi.c b/hw/pci-host/gpex-acpi.c
index f69413ea2c..a93b55c991 100644
--- a/hw/pci-host/gpex-acpi.c
+++ b/hw/pci-host/gpex-acpi.c
@@ -7,7 +7,8 @@
 #include "hw/pci/pcie_host.h"
 #include "hw/acpi/cxl.h"
 
-static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
+static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq,
+                                          Aml *scope, uint8_t bus_num)
 {
     Aml *method, *crs;
     int i, slot_no;
@@ -20,7 +21,7 @@ static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
             Aml *pkg = aml_package(4);
             aml_append(pkg, aml_int((slot_no << 16) | 0xFFFF));
             aml_append(pkg, aml_int(i));
-            aml_append(pkg, aml_name("GSI%d", gsi));
+            aml_append(pkg, aml_name("L%.02X%d", bus_num, gsi));
             aml_append(pkg, aml_int(0));
             aml_append(rt_pkg, pkg);
         }
@@ -30,7 +31,7 @@ static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
     /* Create GSI link device */
     for (i = 0; i < PCI_NUM_PINS; i++) {
         uint32_t irqs = irq + i;
-        Aml *dev_gsi = aml_device("GSI%d", i);
+        Aml *dev_gsi = aml_device("L%.02X%d", bus_num, i);
         aml_append(dev_gsi, aml_name_decl("_HID", aml_string("PNP0C0F")));
         aml_append(dev_gsi, aml_name_decl("_UID", aml_int(i)));
         crs = aml_resource_template();
@@ -45,7 +46,7 @@ static void acpi_dsdt_add_pci_route_table(Aml *dev, uint32_t irq)
         aml_append(dev_gsi, aml_name_decl("_CRS", crs));
         method = aml_method("_SRS", 1, AML_NOTSERIALIZED);
         aml_append(dev_gsi, method);
-        aml_append(dev, dev_gsi);
+        aml_append(scope, dev_gsi);
     }
 }
 
@@ -174,7 +175,7 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
                 aml_append(dev, aml_name_decl("_PXM", aml_int(numa_node)));
             }
 
-            acpi_dsdt_add_pci_route_table(dev, cfg->irq);
+            acpi_dsdt_add_pci_route_table(dev, cfg->irq, scope, bus_num);
 
             /*
              * Resources defined for PXBs are composed of the following parts:
@@ -205,7 +206,7 @@ void acpi_dsdt_add_gpex(Aml *scope, struct GPEXConfig *cfg)
     aml_append(dev, aml_name_decl("_STR", aml_unicode("PCIe 0 Device")));
     aml_append(dev, aml_name_decl("_CCA", aml_int(1)));
 
-    acpi_dsdt_add_pci_route_table(dev, cfg->irq);
+    acpi_dsdt_add_pci_route_table(dev, cfg->irq, scope, 0);
 
     method = aml_method("_CBA", 0, AML_NOTSERIALIZED);
     aml_append(method, aml_return(aml_int(cfg->ecam.base)));
-- 
2.43.0