hw/arm/virt_acpi_build: Generate DBG2 table

ARM SBBR specification mandates DBG2 table (Debug Port Table 2)
since v1.0 (ARM DEN0044F 8.3.1.7 DBG2).

The DBG2 table allows to describe one or more debug ports.

Generate an DBG2 table featuring a single debug port, the PL011.

The DBG2 specification can be found at
"Microsoft Debug Port Table 2 (DBG2)"
https://docs.microsoft.com/en-us/windows-hardware/drivers/bringup/acpi-debug-port-table?redirectedfrom=MSDN

Signed-off-by: Eric Auger <eric.auger@redhat.com>
Reviewed-by: Andrew Jones <drjones@redhat.com>
Reviewed-by: Igor Mammedov <imammedo@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Message-Id: <20211019080037.930641-3-eric.auger@redhat.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

1 files changed, 62 insertions, 1 deletions

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 9c4730f4ab..d3bb4cba3e 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -626,6 +626,64 @@ build_gtdt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
     acpi_table_end(linker, &table);
 }
 
+/* Debug Port Table 2 (DBG2) */
+static void
+build_dbg2(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
+{
+    AcpiTable table = { .sig = "DBG2", .rev = 0, .oem_id = vms->oem_id,
+                        .oem_table_id = vms->oem_table_id };
+    int dbg2devicelength;
+    const char name[] = "COM0";
+    const int namespace_length = sizeof(name);
+
+    acpi_table_begin(&table, table_data);
+
+    dbg2devicelength = 22 + /* BaseAddressRegister[] offset */
+                       12 + /* BaseAddressRegister[] */
+                       4 + /* AddressSize[] */
+                       namespace_length /* NamespaceString[] */;
+
+    /* OffsetDbgDeviceInfo */
+    build_append_int_noprefix(table_data, 44, 4);
+    /* NumberDbgDeviceInfo */
+    build_append_int_noprefix(table_data, 1, 4);
+
+    /* Table 2. Debug Device Information structure format */
+    build_append_int_noprefix(table_data, 0, 1); /* Revision */
+    build_append_int_noprefix(table_data, dbg2devicelength, 2); /* Length */
+    /* NumberofGenericAddressRegisters */
+    build_append_int_noprefix(table_data, 1, 1);
+    /* NameSpaceStringLength */
+    build_append_int_noprefix(table_data, namespace_length, 2);
+    build_append_int_noprefix(table_data, 38, 2); /* NameSpaceStringOffset */
+    build_append_int_noprefix(table_data, 0, 2); /* OemDataLength */
+    /* OemDataOffset (0 means no OEM data) */
+    build_append_int_noprefix(table_data, 0, 2);
+
+    /* Port Type */
+    build_append_int_noprefix(table_data, 0x8000 /* Serial */, 2);
+    /* Port Subtype */
+    build_append_int_noprefix(table_data, 0x3 /* ARM PL011 UART */, 2);
+    build_append_int_noprefix(table_data, 0, 2); /* Reserved */
+    /* BaseAddressRegisterOffset */
+    build_append_int_noprefix(table_data, 22, 2);
+    /* AddressSizeOffset */
+    build_append_int_noprefix(table_data, 34, 2);
+
+    /* BaseAddressRegister[] */
+    build_append_gas(table_data, AML_AS_SYSTEM_MEMORY, 8, 0, 1,
+                     vms->memmap[VIRT_UART].base);
+
+    /* AddressSize[] */
+    build_append_int_noprefix(table_data,
+                              vms->memmap[VIRT_UART].size, 4);
+
+    /* NamespaceString[] */
+    g_array_append_vals(table_data, name, namespace_length);
+
+    acpi_table_end(linker, &table);
+};
+
 /*
  * ACPI spec, Revision 5.1 Errata A
  * 5.2.12 Multiple APIC Description Table (MADT)
@@ -885,7 +943,7 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables)
     dsdt = tables_blob->len;
     build_dsdt(tables_blob, tables->linker, vms);
 
-    /* FADT MADT GTDT MCFG SPCR pointed to by RSDT */
+    /* FADT MADT GTDT MCFG SPCR DBG2 pointed to by RSDT */
     acpi_add_table(table_offsets, tables_blob);
     build_fadt_rev5(tables_blob, tables->linker, vms, dsdt);
 
@@ -908,6 +966,9 @@ void virt_acpi_build(VirtMachineState *vms, AcpiBuildTables *tables)
     acpi_add_table(table_offsets, tables_blob);
     build_spcr(tables_blob, tables->linker, vms);
 
+    acpi_add_table(table_offsets, tables_blob);
+    build_dbg2(tables_blob, tables->linker, vms);
+
     if (vms->ras) {
         build_ghes_error_table(tables->hardware_errors, tables->linker);
         acpi_add_table(table_offsets, tables_blob);