[PATCH 3/5] ASoC: tas2783-sdw: use the BIOS speaker ID in the firmware name

[Matthew Schwartz <matthew.schwartz@linux.dev>]

Some boards have TAS2783 firmware in linux-firmware named
SSID-SPKID-LINK-0xUID.bin, with a speaker ID ahead of the link ID (the
HP 8EA1 has its amps on link 0 and ships 8EA1-{0,1}-0-0x*.bin). The
driver only builds the three-field SSID-LINK-0xUID name, so these boards
never load firmware. On the ASUS ROG Xbox Ally X20 (SSID 1954) the BIOS
provides the speaker ID in a 4-byte SPEAKER_ID EFI variable, and only
the four-field 1954-*-*-0x*.bin files exist.

Read SPEAKER_ID once and request the four-field name first when it is
present. Boards without the variable keep the current names, and the
unprefixed three-field name is still tried if the four-field file is
missing.

Signed-off-by: Matthew Schwartz <matthew.schwartz@linux.dev>
---
 sound/soc/codecs/tas2783-sdw.c | 42 +++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/sound/soc/codecs/tas2783-sdw.c b/sound/soc/codecs/tas2783-sdw.c
index a57230e01f755..db234c54aa2ac 100644
--- a/sound/soc/codecs/tas2783-sdw.c
+++ b/sound/soc/codecs/tas2783-sdw.c
@@ -46,6 +46,8 @@
 #define TAS2783_PROBE_TIMEOUT 5000
 #define TAS2783_CALI_GUID EFI_GUID(0x1f52d2a1, 0xbb3a, 0x457d, 0xbc, \
 				   0x09, 0x43, 0xa3, 0xf4, 0x31, 0x0a, 0x92)
+#define TAS2783_SPKID_GUID EFI_GUID(0xaa61eaaf, 0x6e83, 0x7523, 0xb0, \
+				    0xd0, 0x7d, 0xf7, 0x4b, 0xb2, 0x4a, 0x81)
 
 static const u32 tas2783_cali_reg[] = {
 	TAS2783_CAL_R0,
@@ -104,6 +106,11 @@ struct tas2783_prv {
 	bool fw_dl_success;
 	/* use fallback fw name */
 	bool fw_use_fallback;
+#if IS_ENABLED(CONFIG_PCI)
+	/* UEFI speaker ID, read once */
+	int spk_id;
+	bool spk_id_read;
+#endif
 };
 
 static const struct reg_default tas2783_reg_default[] = {
@@ -1156,6 +1163,26 @@ static const struct dev_pm_ops tas2783_sdca_pm = {
 	RUNTIME_PM_OPS(tas2783_sdca_dev_suspend, tas2783_sdca_dev_resume, NULL)
 };
 
+#if IS_ENABLED(CONFIG_PCI)
+/* BIOS speaker ID that selects the SSID-SPKID-LINK-UID firmware name */
+static int tas2783_get_spk_id(void)
+{
+	efi_guid_t guid = TAS2783_SPKID_GUID;
+	unsigned long size = sizeof(u32);
+	efi_status_t status;
+	u32 spk_id = 0;
+
+	if (!efi_rt_services_supported(EFI_RT_SUPPORTED_GET_VARIABLE))
+		return -ENOENT;
+
+	status = efi.get_variable(L"SPEAKER_ID", &guid, NULL, &size, &spk_id);
+	if (status != EFI_SUCCESS)
+		return -ENOENT;
+
+	return spk_id;
+}
+#endif
+
 static void tas_generate_fw_name(struct sdw_slave *slave, char *name, size_t size)
 {
 	struct sdw_bus *bus = slave->bus;
@@ -1170,9 +1197,18 @@ static void tas_generate_fw_name(struct sdw_slave *slave, char *name, size_t siz
 	for (; dev; dev = dev->parent) {
 		if (dev->bus == &pci_bus_type) {
 			pci = to_pci_dev(dev);
-			scnprintf(name, size, "%04X-%1X-%s%1X.bin",
-				  pci->subsystem_device, bus->link_id,
-				  fw_uid_prefix, unique_id);
+			if (!tas_dev->spk_id_read) {
+				tas_dev->spk_id = tas2783_get_spk_id();
+				tas_dev->spk_id_read = true;
+			}
+			if (tas_dev->spk_id >= 0 && !tas_dev->fw_use_fallback)
+				scnprintf(name, size, "%04X-%X-%1X-0x%1X.bin",
+					  pci->subsystem_device, tas_dev->spk_id,
+					  bus->link_id, unique_id);
+			else
+				scnprintf(name, size, "%04X-%1X-%s%1X.bin",
+					  pci->subsystem_device, bus->link_id,
+					  fw_uid_prefix, unique_id);
 			pci_found = true;
 			break;
 		}
-- 
2.56.0