[PATCH for-6.2] hw/arm/virt_acpi_build: Generate DBG2 table

[Eric Auger <eric.auger@redhat.com>]

ARM SBBR specification mandates DBG2 table (Debug Port Table 2).
this latter 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:
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>

---

Tested by comparing the content with the table generated
by EDK2 along with the SBSA-REF machine (code generated by
DynamicTablesPkg/Library/Acpi/Arm/AcpiDbg2LibArm/Dbg2Generator.c).

I reused the Generic Address Structure filled by QEMU in the SPCR, ie.
bit_width = 8 and byte access. While EDK2 sets bit_width = 32 and
dword access. Also the name exposed by acpica tools is different:
'COM0' in my case where '\_SB.COM0' in SBSA-REF case?
---
 hw/arm/virt-acpi-build.c    | 77 ++++++++++++++++++++++++++++++++++++-
 include/hw/acpi/acpi-defs.h | 50 ++++++++++++++++++++++++
 2 files changed, 126 insertions(+), 1 deletion(-)

diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
index 037cc1fd82..35f27b41df 100644
--- a/hw/arm/virt-acpi-build.c
+++ b/hw/arm/virt-acpi-build.c
@@ -563,6 +563,78 @@ build_gtdt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
                  vms->oem_table_id);
 }
 
+#define ACPI_DBG2_PL011_UART_LENGTH 0x1000
+
+/* DBG2 */
+static void
+build_dbg2(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
+{
+    int addr_offset, addrsize_offset, namespace_offset, namespace_length;
+    const MemMapEntry *uart_memmap = &vms->memmap[VIRT_UART];
+    struct AcpiGenericAddress *base_address;
+    int dbg2_start = table_data->len;
+    AcpiDbg2Device *dbg2dev;
+    char name[] = "COM0";
+    AcpiDbg2Table *dbg2;
+    uint32_t *addr_size;
+    uint8_t *namespace;
+
+    dbg2 = acpi_data_push(table_data, sizeof *dbg2);
+    dbg2->info_offset = sizeof *dbg2;
+    dbg2->info_count = 1;
+
+    /* debug device info structure */
+
+    dbg2dev = acpi_data_push(table_data, sizeof(AcpiDbg2Device));
+
+    dbg2dev->revision = 0;
+    namespace_length = sizeof name;
+    dbg2dev->length = sizeof *dbg2dev + sizeof(struct AcpiGenericAddress) +
+                      4 + namespace_length;
+    dbg2dev->register_count = 1;
+
+    addr_offset = sizeof *dbg2dev;
+    addrsize_offset = addr_offset + sizeof(struct AcpiGenericAddress);
+    namespace_offset = addrsize_offset + 4;
+
+    dbg2dev->namepath_length = cpu_to_le16(namespace_length);
+    dbg2dev->namepath_offset = cpu_to_le16(namespace_offset);
+    dbg2dev->oem_data_length = cpu_to_le16(0);
+    dbg2dev->oem_data_offset = cpu_to_le16(0); /* No OEM data is present */
+    dbg2dev->port_type = cpu_to_le16(ACPI_DBG2_SERIAL_PORT);
+    dbg2dev->port_subtype = cpu_to_le16(ACPI_DBG2_ARM_PL011);
+
+    dbg2dev->base_address_offset = cpu_to_le16(addr_offset);
+    dbg2dev->address_size_offset = cpu_to_le16(addrsize_offset);
+
+    /*
+     * variable length content:
+     * BaseAddressRegister[1]
+     * AddressSize[1]
+     * NamespaceString[1]
+     */
+
+    base_address = acpi_data_push(table_data,
+                                  sizeof(struct AcpiGenericAddress));
+
+    base_address->space_id = AML_SYSTEM_MEMORY;
+    base_address->bit_width = 8;
+    base_address->bit_offset = 0;
+    base_address->access_width = 1;
+    base_address->address = cpu_to_le64(uart_memmap->base);
+
+    addr_size = acpi_data_push(table_data, sizeof *addr_size);
+    *addr_size = cpu_to_le32(ACPI_DBG2_PL011_UART_LENGTH);
+
+    namespace = acpi_data_push(table_data, namespace_length);
+    memcpy(namespace, name, namespace_length);
+
+    build_header(linker, table_data,
+                 (void *)(table_data->data + dbg2_start), "DBG2",
+                 table_data->len - dbg2_start, 3, vms->oem_id,
+                 vms->oem_table_id);
+}
+
 /* MADT */
 static void
 build_madt(GArray *table_data, BIOSLinker *linker, VirtMachineState *vms)
@@ -790,7 +862,7 @@ 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);
 
@@ -813,6 +885,9 @@ 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);
diff --git a/include/hw/acpi/acpi-defs.h b/include/hw/acpi/acpi-defs.h
index cf9f44299c..bdb2ebed2c 100644
--- a/include/hw/acpi/acpi-defs.h
+++ b/include/hw/acpi/acpi-defs.h
@@ -618,4 +618,54 @@ struct AcpiIortRC {
 } QEMU_PACKED;
 typedef struct AcpiIortRC AcpiIortRC;
 
+/* DBG2 */
+
+/* Types for port_type field above */
+
+#define ACPI_DBG2_SERIAL_PORT       0x8000
+#define ACPI_DBG2_1394_PORT         0x8001
+#define ACPI_DBG2_USB_PORT          0x8002
+#define ACPI_DBG2_NET_PORT          0x8003
+
+/* Subtypes for port_subtype field above */
+
+#define ACPI_DBG2_16550_COMPATIBLE  0x0000
+#define ACPI_DBG2_16550_SUBSET      0x0001
+#define ACPI_DBG2_ARM_PL011         0x0003
+#define ACPI_DBG2_ARM_SBSA_32BIT    0x000D
+#define ACPI_DBG2_ARM_SBSA_GENERIC  0x000E
+#define ACPI_DBG2_ARM_DCC           0x000F
+#define ACPI_DBG2_BCM2835           0x0010
+
+#define ACPI_DBG2_1394_STANDARD     0x0000
+
+#define ACPI_DBG2_USB_XHCI          0x0000
+#define ACPI_DBG2_USB_EHCI          0x0001
+
+/* Debug Device Information Subtable */
+
+struct AcpiDbg2Device {
+    uint8_t  revision;
+    uint16_t length;
+    uint8_t  register_count; /* Number of base_address registers */
+    uint16_t namepath_length;
+    uint16_t namepath_offset;
+    uint16_t oem_data_length;
+    uint16_t oem_data_offset;
+    uint16_t port_type;
+    uint16_t port_subtype;
+    uint8_t  reserved[2];
+    uint16_t base_address_offset;
+    uint16_t address_size_offset;
+}  QEMU_PACKED;
+typedef struct AcpiDbg2Device AcpiDbg2Device;
+
+struct AcpiDbg2Table {
+    ACPI_TABLE_HEADER_DEF /* ACPI common table header */
+    uint32_t info_offset; /* offset to the first debug struct */
+    uint32_t info_count;  /* number of debug device info struct entries */
+    uint8_t  dbg2_device_info[];
+} QEMU_PACKED;
+typedef struct AcpiDbg2Table AcpiDbg2Table;
+
 #endif
-- 
2.26.3