ASoC: sdca: extract function initialization table

The MIPI DisCo 2.1 spec defines an "initialization table", which
contains a list of 4-byte addresses and 1 byte value. The registers
need to be updated during the initial boot and if context is lost.

Note that the data in the table is represented as an ACPI "buffer",
but the buffer is accessible with a DSD property:

ToUUID ("edb12dd0-363d-4085-a3d2-49522ca160c4")
Package (0x01)
{
  Package (0x02)
  {
    "mipi-sdca-function-initialization-table",
    "BUF0"
  }
}

Name (BUF0, Buffer (0x01BD)
{
  0x20, 0xC7, 0x00, 0x00, 0x17, 0x21, 0xC7, 0x00,
  0x00, 0x00, 0x22, 0xC7, 0x00, 0x00, 0x3E, 0x23,
  0xC7, 0x00, 0x00, 0x06, 0x24, 0xC7, 0x00, 0x00,
...
}

The connection between _DSD and ACPI is defined in the 'Data Buffer'
extension [1] already supported in the Linux kernel.

[1] https://github.com/UEFI/DSD-Guide/blob/main/src/dsd-guide.adoc#buffer-data-extension-uuid

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>

Author: plbossart

include/sound/sdca_function.h

@@ -106,6 +106,9 @@ struct sdca_entity {
  * @function_busy_max_delay_us: indicates if hardware can assert the Function_Busy
  * bit, which requires special-casing of the 'Command Ignored' response. If zero,
  * then the Host shall assume this bit is never asserted.
+ * @initialization_table: set of 4-byte address/byte value to set-up the Function
+ * during boot and resume if context is lost
+ * @initialization_table_size: size of @initialization_table
  */
 struct sdca_function {
 	u8 adr; /* limited range since only 8 functions can be supported */
@@ -114,6 +117,8 @@ struct sdca_function {
 	int num_entities;
 	struct sdca_entity *entities;
 	u32 function_busy_max_delay_us;
+	u8 *initialization_table;
+	int initialization_table_size;
 };
 
 /**

sound/soc/sdca/sdca_functions.c

@@ -253,6 +253,48 @@ static int find_sdca_entities_connections(struct device *dev,
 	return 0;
 }
 
+static int find_sdca_function_initialization_table(struct device *dev,
+						   struct fwnode_handle *function_node,
+						   struct sdca_function *function)
+{
+	u8 *initialization_table;
+	int nval;
+	int ret;
+
+	nval = fwnode_property_count_u8(function_node,
+					"mipi-sdca-function-initialization-table");
+	if (nval <= 0)
+		return nval;
+
+	/* make sure the table contains a set of 4-byte addresses and one-byte value */
+	if (nval % 5) {
+		dev_err(dev, "%s: %pfwP: invalid initialization table size %#x\n",
+			__func__, function_node, nval);
+		return -EINVAL;
+	}
+
+	dev_info(dev, "%s: %pfwP: initialization table size %#x\n",
+		 __func__, function_node, nval);
+
+	initialization_table = devm_kcalloc(dev, nval,
+					    sizeof(*initialization_table),
+					    GFP_KERNEL);
+	if (!initialization_table)
+		return -ENOMEM;
+
+	ret = fwnode_property_read_u8_array(function_node,
+					    "mipi-sdca-function-initialization-table",
+					    initialization_table,
+					    nval);
+	if (ret < 0)
+		return ret;
+
+	function->initialization_table = initialization_table;
+	function->initialization_table_size = nval;
+
+	return 0;
+}
+
 static int find_sdca_function(struct acpi_device *adev, void *data)
 {
 	struct fwnode_handle *function_node = acpi_fwnode_handle(adev);
@@ -348,6 +390,11 @@ static int find_sdca_function(struct acpi_device *adev, void *data)
 			topology_features;
 	}
 
+	ret = find_sdca_function_initialization_table(parent, function_node,
+						      &sdca->functions[sdca->function_count]);
+	if (ret < 0)
+		return ret;
+
 	ret = find_sdca_entities(&adev->dev,
 				 function_node,
 				 &sdca->functions[sdca->function_count]);