acpi: Generate object for coreboot table region

Generate an object to describe the coreboot table region in ACPI
with the HID "CORE0000" so it can be used by kernel drivers.

To keep track of the "CORE" HID usage add them to an enum and add
a function to generate the HID in AML:  Name (_HID, "CORExxxx")

BUG=chromium:589817
BRANCH=none
TEST=build and boot on chell, dump SSDT to verify contents:

Device (CTBL)
{
    Name (_HID, "CORE0000")  // _HID: Hardware ID
    Name (_UID, Zero)  // _UID: Unique ID
    Method (_STA, 0, NotSerialized)  // _STA: Status
    {
        Return (0x0F)
    }
    Name (_CRS, ResourceTemplate ()  // _CRS: Current Resource Settings
    {
        Memory32Fixed (ReadOnly,
            0x7AB84000,         // Address Base
            0x00008000,         // Address Length
            )
    })
}

Change-Id: I2c681c1fee02d52b8df2e72f6f6f0b76fa9592fb
Signed-off-by: Duncan Laurie <dlaurie@chromium.org>
Reviewed-on: https://review.coreboot.org/16056
Tested-by: build bot (Jenkins)
Reviewed-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-by: Patrick Georgi <pgeorgi@google.com>
Reviewed-by: Paul Menzel <paulepanter@users.sourceforge.net>

src/arch/x86/acpi.c

@@ -307,6 +307,29 @@ static void acpi_create_tcpa(acpi_tcpa_t *tcpa)
 	header->checksum = acpi_checksum((void *)tcpa, header->length);
 }
 
+static void acpi_ssdt_write_cbtable(void)
+{
+	const struct cbmem_entry *cbtable;
+	uintptr_t base;
+	uint32_t size;
+
+	cbtable = cbmem_entry_find(CBMEM_ID_CBTABLE);
+	if (!cbtable)
+		return;
+	base = (uintptr_t)cbmem_entry_start(cbtable);
+	size = cbmem_entry_size(cbtable);
+
+	acpigen_write_device("CTBL");
+	acpigen_write_coreboot_hid(COREBOOT_ACPI_ID_CBTABLE);
+	acpigen_write_name_integer("_UID", 0);
+	acpigen_write_STA(ACPI_STATUS_DEVICE_ALL_ON);
+	acpigen_write_name("_CRS");
+	acpigen_write_resourcetemplate_header();
+	acpigen_write_mem32fixed(0, base, size);
+	acpigen_write_resourcetemplate_footer();
+	acpigen_pop_len();
+}
+
 void acpi_create_ssdt_generator(acpi_header_t *ssdt, const char *oem_table_id)
 {
 	unsigned long current = (unsigned long)ssdt + sizeof(acpi_header_t);
@@ -323,6 +346,10 @@ void acpi_create_ssdt_generator(acpi_header_t *ssdt, const char *oem_table_id)
 	ssdt->length = sizeof(acpi_header_t);
 
 	acpigen_set_current((char *) current);
+
+	/* Write object to declare coreboot tables */
+	acpi_ssdt_write_cbtable();
+
 	{
 		struct device *dev;
 		for (dev = all_devices; dev; dev = dev->next)

src/arch/x86/acpigen.c

@@ -220,6 +220,14 @@ void acpigen_write_string(const char *string)
 	acpigen_emit_string(string);
 }
 
+void acpigen_write_coreboot_hid(enum coreboot_acpi_ids id)
+{
+	char hid[9]; /* CORExxxx */
+
+	snprintf(hid, sizeof(hid), "%.4s%04u", COREBOOT_ACPI_ID, id);
+	acpigen_write_name_string("_HID", hid);
+}
+
 /*
  * The naming conventions for ACPI namespace names are a bit tricky as
  * each element has to be 4 chars wide ("All names are a fixed 32 bits.")

src/arch/x86/include/arch/acpi.h

@@ -57,6 +57,12 @@
 #define ACPI_TABLE_CREATOR	"COREBOOT"  /* Must be exactly 8 bytes long! */
 #define OEM_ID			"CORE  "    /* Must be exactly 6 bytes long! */
 #define ASLC			"CORE"      /* Must be exactly 4 bytes long! */
+#define COREBOOT_ACPI_ID	"CORE"      /* ACPI ID for coreboot HIDs */
+
+/* List of ACPI HID that use the coreboot ACPI ID */
+enum coreboot_acpi_ids {
+	COREBOOT_ACPI_ID_CBTABLE,	/* CORE0000 */
+};
 
 /* RSDP (Root System Description Pointer) */
 typedef struct acpi_rsdp {

src/arch/x86/include/arch/acpigen.h

@@ -63,6 +63,7 @@ void acpigen_write_name_dword(const char *name, uint32_t val);
 void acpigen_write_name_qword(const char *name, uint64_t val);
 void acpigen_write_name_byte(const char *name, uint8_t val);
 void acpigen_write_name_integer(const char *name, uint64_t val);
+void acpigen_write_coreboot_hid(enum coreboot_acpi_ids id);
 void acpigen_write_scope(const char *name);
 void acpigen_write_method(const char *name, int nargs);
 void acpigen_write_device(const char *name);