[PATCH] ALSA: HDA: intel-sdw-acpi: add kernel parameter to select alternate controller

[Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>]

Existing DSDT or SSDT platforms hard-code clock and frame shape
configurations. For validation, we'd like to use alternate
configurations. It's not always possible to generate new tables due to
missing symbols, and modifying existing objects usually leads to
AE_OBJECT_EXIST errors.

The mechanism suggested in this patch is to add a NEW ACPI controller
device with a different _ADR value. e.g.

 Scope (_SB_.PC00.RP08.PXSX.HDAS) {

  	Device (SDWP)
            {
                Name (_ADR, 0x40000001)  // _ADR: Address

The desired _ADR can be passed as a parameter with

options snd-intel-sdw-acpi sdw_ctrl_addr=0x40000001

This solution leads to minimal tables with just what the developers or
validation engineers need, and without overriding any of the existing
firmware definitions. It's consistent with the recommendation to
extend ACPI definitions and not redefine them with a risk of conflict.

Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@xxxxxxxxxxxxxxx>
Reviewed-by: Rander Wang <rander.wang@xxxxxxxxx>
Reviewed-by: Bard Liao <yung-chuan.liao@xxxxxxxxxxxxxxx>
---
 sound/hda/intel-sdw-acpi.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/sound/hda/intel-sdw-acpi.c b/sound/hda/intel-sdw-acpi.c
index b57d72ea4503..5f60658c6051 100644
--- a/sound/hda/intel-sdw-acpi.c
+++ b/sound/hda/intel-sdw-acpi.c
@@ -23,6 +23,10 @@ static int ctrl_link_mask;
 module_param_named(sdw_link_mask, ctrl_link_mask, int, 0444);
 MODULE_PARM_DESC(sdw_link_mask, "Intel link mask (one bit per link)");
 
+static ulong ctrl_addr = 0x40000000;
+module_param_named(sdw_ctrl_addr, ctrl_addr, ulong, 0444);
+MODULE_PARM_DESC(sdw_ctrl_addr, "Intel SoundWire Controller _ADR");
+
 static bool is_link_enabled(struct fwnode_handle *fw_node, u8 idx)
 {
 	struct fwnode_handle *link;
@@ -141,6 +145,9 @@ static acpi_status sdw_intel_acpi_cb(acpi_handle handle, u32 level,
 	if (FIELD_GET(GENMASK(31, 28), adr) != SDW_LINK_TYPE)
 		return AE_OK; /* keep going */
 
+	if (adr != ctrl_addr)
+		return AE_OK; /* keep going */
+
 	/* found the correct SoundWire controller */
 	info->handle = handle;
 
-- 
2.40.1