acpi: Support generating a multi-function _DSM for devices

Add a function to generate ACPI code for a _DSM method for a device.
This includes functions for starting and ending each part of the _DSM.

Signed-off-by: Simon Glass <sjg@chromium.org>
[bmeng: fix the "new blank line at EOF" git warning]
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>

2 files changed, 97 insertions, 0 deletions

diff --git a/lib/acpi/acpi_device.c b/lib/acpi/acpi_device.c
index 3c75b6d962..8248664a10 100644
--- a/lib/acpi/acpi_device.c
+++ b/lib/acpi/acpi_device.c
@@ -487,6 +487,49 @@ int acpi_device_add_power_res(struct acpi_ctx *ctx, u32 tx_state_val,
 	return 0;
 }
 
+int acpi_device_write_dsm_i2c_hid(struct acpi_ctx *ctx,
+				  int hid_desc_reg_offset)
+{
+	int ret;
+
+	acpigen_write_dsm_start(ctx);
+	ret = acpigen_write_dsm_uuid_start(ctx, ACPI_DSM_I2C_HID_UUID);
+	if (ret)
+		return log_ret(ret);
+
+	acpigen_write_dsm_uuid_start_cond(ctx, 0);
+	/* ToInteger (Arg1, Local2) */
+	acpigen_write_to_integer(ctx, ARG1_OP, LOCAL2_OP);
+	/* If (LEqual (Local2, 0x0)) */
+	acpigen_write_if_lequal_op_int(ctx, LOCAL2_OP, 0x0);
+	/*   Return (Buffer (One) { 0x1f }) */
+	acpigen_write_return_singleton_buffer(ctx, 0x1f);
+	acpigen_pop_len(ctx);	/* Pop : If */
+	/* Else */
+	acpigen_write_else(ctx);
+	/*   If (LEqual (Local2, 0x1)) */
+	acpigen_write_if_lequal_op_int(ctx, LOCAL2_OP, 0x1);
+	/*     Return (Buffer (One) { 0x3f }) */
+	acpigen_write_return_singleton_buffer(ctx, 0x3f);
+	acpigen_pop_len(ctx);	/* Pop : If */
+	/*   Else */
+	acpigen_write_else(ctx);
+	/*     Return (Buffer (One) { 0x0 }) */
+	acpigen_write_return_singleton_buffer(ctx, 0x0);
+	acpigen_pop_len(ctx);	/* Pop : Else */
+	acpigen_pop_len(ctx);	/* Pop : Else */
+	acpigen_write_dsm_uuid_end_cond(ctx);
+
+	acpigen_write_dsm_uuid_start_cond(ctx, 1);
+	acpigen_write_return_byte(ctx, hid_desc_reg_offset);
+	acpigen_write_dsm_uuid_end_cond(ctx);
+
+	acpigen_write_dsm_uuid_end(ctx);
+	acpigen_write_dsm_end(ctx);
+
+	return 0;
+}
+
 /* ACPI 6.3 section 6.4.3.8.2.1 - I2cSerialBus() */
 static void acpi_device_write_i2c(struct acpi_ctx *ctx,
 				  const struct acpi_i2c *i2c)
diff --git a/lib/acpi/acpigen.c b/lib/acpi/acpigen.c
index 2518bf83dd..d859f37841 100644
--- a/lib/acpi/acpigen.c
+++ b/lib/acpi/acpigen.c
@@ -609,6 +609,60 @@ void acpigen_write_return_byte(struct acpi_ctx *ctx, uint arg)
 	acpigen_write_byte(ctx, arg);
 }
 
+void acpigen_write_dsm_start(struct acpi_ctx *ctx)
+{
+	/* Method (_DSM, 4, Serialized) */
+	acpigen_write_method_serialized(ctx, "_DSM", 4);
+
+	/* ToBuffer (Arg0, Local0) */
+	acpigen_write_to_buffer(ctx, ARG0_OP, LOCAL0_OP);
+}
+
+int acpigen_write_dsm_uuid_start(struct acpi_ctx *ctx, const char *uuid)
+{
+	int ret;
+
+	/* If (LEqual (Local0, ToUUID(uuid))) */
+	acpigen_write_if(ctx);
+	acpigen_emit_byte(ctx, LEQUAL_OP);
+	acpigen_emit_byte(ctx, LOCAL0_OP);
+	ret = acpigen_write_uuid(ctx, uuid);
+	if (ret)
+		return log_msg_ret("uuid", ret);
+
+	/* ToInteger (Arg2, Local1) */
+	acpigen_write_to_integer(ctx, ARG2_OP, LOCAL1_OP);
+
+	return 0;
+}
+
+void acpigen_write_dsm_uuid_start_cond(struct acpi_ctx *ctx, int seq)
+{
+	/* If (LEqual (Local1, i)) */
+	acpigen_write_if_lequal_op_int(ctx, LOCAL1_OP, seq);
+}
+
+void acpigen_write_dsm_uuid_end_cond(struct acpi_ctx *ctx)
+{
+	acpigen_pop_len(ctx);	/* If */
+}
+
+void acpigen_write_dsm_uuid_end(struct acpi_ctx *ctx)
+{
+	/* Default case: Return (Buffer (One) { 0x0 }) */
+	acpigen_write_return_singleton_buffer(ctx, 0x0);
+
+	acpigen_pop_len(ctx);	/* If (LEqual (Local0, ToUUID(uuid))) */
+}
+
+void acpigen_write_dsm_end(struct acpi_ctx *ctx)
+{
+	/* Return (Buffer (One) { 0x0 }) */
+	acpigen_write_return_singleton_buffer(ctx, 0x0);
+
+	acpigen_pop_len(ctx);	/* Method _DSM */
+}
+
 /**
  * acpigen_get_dw0_in_local5() - Generate code to put dw0 cfg0 in local5
  *