acpi: Add support for SSDT generation

Some devices need to generate code for the Secondary System Descriptor
Table (SSDT). Add a method to handle this.

Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Wolfgang Wallner <wolfgang.wallner@br-automation.com>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>

arch/sandbox/dts/test.dts

@@ -256,6 +256,7 @@
 
 	acpi-test {
 		compatible = "denx,u-boot-acpi-test";
+		acpi-ssdt-test-data = "ab";
 		child {
 			compatible = "denx,u-boot-acpi-test";
 		};
@@ -263,6 +264,7 @@
 
 	acpi-test2 {
 		compatible = "denx,u-boot-acpi-test";
+		acpi-ssdt-test-data = "cd";
 	};
 
 	clocks {

drivers/core/acpi.c

@@ -18,6 +18,7 @@
 /* Type of method to call */
 enum method_t {
 	METHOD_WRITE_TABLES,
+	METHOD_FILL_SSDT,
 };
 
 /* Prototype for all methods */
@@ -51,6 +52,8 @@ acpi_method acpi_get_method(struct udevice *dev, enum method_t method)
 		switch (method) {
 		case METHOD_WRITE_TABLES:
 			return aops->write_tables;
+		case METHOD_FILL_SSDT:
+			return aops->fill_ssdt;
 		}
 	}
 
@@ -84,6 +87,17 @@ int acpi_recurse_method(struct acpi_ctx *ctx, struct udevice *parent,
 	return 0;
 }
 
+int acpi_fill_ssdt(struct acpi_ctx *ctx)
+{
+	int ret;
+
+	log_debug("Writing SSDT tables\n");
+	ret = acpi_recurse_method(ctx, dm_root(), METHOD_FILL_SSDT);
+	log_debug("Writing SSDT finished, err=%d\n", ret);
+
+	return ret;
+}
+
 int acpi_write_dev_tables(struct acpi_ctx *ctx)
 {
 	int ret;

include/dm/acpi.h

@@ -74,6 +74,19 @@ struct acpi_ops {
 	 * @return 0 if OK, -ve on error
 	 */
 	int (*write_tables)(const struct udevice *dev, struct acpi_ctx *ctx);
+
+	/**
+	 * fill_ssdt() - Generate SSDT code for a device
+	 *
+	 * This is called to create the SSDT code. The method should write out
+	 * whatever ACPI code is needed by this device. It will end up in the
+	 * SSDT table.
+	 *
+	 * @dev: Device to write
+	 * @ctx: ACPI context to use
+	 * @return 0 if OK, -ve on error
+	 */
+	int (*fill_ssdt)(const struct udevice *dev, struct acpi_ctx *ctx);
 };
 
 #define device_get_acpi_ops(dev)	((dev)->driver->acpi_ops)
@@ -118,6 +131,16 @@ int acpi_copy_name(char *out_name, const char *name);
  */
 int acpi_write_dev_tables(struct acpi_ctx *ctx);
 
+/**
+ * acpi_fill_ssdt() - Generate ACPI tables for SSDT
+ *
+ * This is called to create the SSDT code for all devices.
+ *
+ * @ctx: ACPI context to use
+ * @return 0 if OK, -ve on error
+ */
+int acpi_fill_ssdt(struct acpi_ctx *ctx);
+
 #endif /* __ACPI__ */
 
 #endif

test/dm/acpi.c

@@ -14,6 +14,7 @@
 #include <version.h>
 #include <tables_csum.h>
 #include <version.h>
+#include <acpi/acpigen.h>
 #include <acpi/acpi_device.h>
 #include <acpi/acpi_table.h>
 #include <dm/acpi.h>
@@ -67,9 +68,23 @@ static int testacpi_get_name(const struct udevice *dev, char *out_name)
 		return acpi_copy_name(out_name, ACPI_TEST_DEV_NAME);
 }
 
+static int testacpi_fill_ssdt(const struct udevice *dev, struct acpi_ctx *ctx)
+{
+	const char *data;
+
+	data = dev_read_string(dev, "acpi-ssdt-test-data");
+	if (data) {
+		while (*data)
+			acpigen_emit_byte(ctx, *data++);
+	}
+
+	return 0;
+}
+
 struct acpi_ops testacpi_ops = {
 	.get_name	= testacpi_get_name,
 	.write_tables	= testacpi_write_tables,
+	.fill_ssdt	= testacpi_fill_ssdt,
 };
 
 static const struct udevice_id testacpi_ids[] = {
@@ -396,3 +411,30 @@ static int dm_test_acpi_device_status(struct unit_test_state *uts)
 	return 0;
 }
 DM_TEST(dm_test_acpi_device_status, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);
+
+/* Test acpi_fill_ssdt() */
+static int dm_test_acpi_fill_ssdt(struct unit_test_state *uts)
+{
+	struct acpi_ctx ctx;
+	u8 *buf;
+
+	buf = malloc(BUF_SIZE);
+	ut_assertnonnull(buf);
+
+	ctx.current = buf;
+	buf[4] = 'z';	/* sentinel */
+	ut_assertok(acpi_fill_ssdt(&ctx));
+
+	/* These values come from acpi-test's acpi-ssdt-test-data property */
+	ut_asserteq('a', buf[0]);
+	ut_asserteq('b', buf[1]);
+
+	/* These values come from acpi-test2's acpi-ssdt-test-data property */
+	ut_asserteq('c', buf[2]);
+	ut_asserteq('d', buf[3]);
+
+	ut_asserteq('z', buf[4]);
+
+	return 0;
+}
+DM_TEST(dm_test_acpi_fill_ssdt, DM_TESTF_SCAN_PDATA | DM_TESTF_SCAN_FDT);