ASoC: cs35l41: Fallback to reading Subsystem ID property if not ACPI

If ACPI is not used, then there is currently no way of reading a
Subsystem ID property used for a system name to uniquely identify
the system in order to load the correct firmware and tuning.
Add a new property which can be read from device tree to be able to set
the system name.

Signed-off-by: Stefan Binding <sbinding@opensource.cirrus.com>
Link: https://patch.msgid.link/20250917153722.94978-3-sbinding@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

diff --git a/sound/soc/codecs/cs35l41.c b/sound/soc/codecs/cs35l41.c
index 224d65987a8df386f29b1c8d41371e6b1ea6ae1b..173d7c59b7254d0674af1f036ac377701be12013 100644 (file)
--- a/sound/soc/codecs/cs35l41.c
+++ b/sound/soc/codecs/cs35l41.c
@@ -7,6 +7,7 @@
 // Author: David Rhodes <david.rhodes@cirrus.com>
 
 #include <linux/acpi.h>
+#include <acpi/acpi_bus.h>
 #include <linux/delay.h>
 #include <linux/err.h>
 #include <linux/init.h>
@@ -1147,45 +1148,55 @@ err_dsp:
        return ret;
 }
 
-#ifdef CONFIG_ACPI
-static int cs35l41_acpi_get_name(struct cs35l41_private *cs35l41)
+static int cs35l41_get_system_name(struct cs35l41_private *cs35l41)
 {
        struct acpi_device *adev = ACPI_COMPANION(cs35l41->dev);
-       acpi_handle handle = acpi_device_handle(adev);
-       const char *hid;
-       const char *sub;
-
-       /* If there is no acpi_device, there is no ACPI for this system, return 0 */
-       if (!adev)
-               return 0;
+       const char *sub = NULL;
+       const char *tmp;
+       int ret = 0;
 
-       sub = acpi_get_subsystem_id(handle);
-       if (IS_ERR(sub)) {
-               /* If no _SUB, fallback to _HID, otherwise fail */
-               if (PTR_ERR(sub) == -ENODATA) {
-                       hid = acpi_device_hid(adev);
-                       /* If dummy hid, return 0 and fallback to legacy firmware path */
-                       if (!strcmp(hid, "device"))
-                               return 0;
-                       sub = kstrdup(hid, GFP_KERNEL);
-                       if (!sub)
-                               sub = ERR_PTR(-ENOMEM);
-
-               } else
-                       return PTR_ERR(sub);
+       /* If there is no acpi_device, there is no ACPI for this system, skip checking ACPI */
+       if (adev) {
+               acpi_handle handle = acpi_device_handle(adev);
+
+               sub = acpi_get_subsystem_id(handle);
+               ret = PTR_ERR_OR_ZERO(sub);
+               if (ret) {
+                       sub = NULL;
+                       /* If no _SUB, fallback to _HID, otherwise fail */
+                       if (ret == -ENODATA) {
+                               tmp = acpi_device_hid(adev);
+                               /* If dummy hid, return 0 and fallback to legacy firmware path */
+                               if (!strcmp(tmp, "device")) {
+                                       ret = 0;
+                                       goto err;
+                               }
+                               sub = kstrdup(tmp, GFP_KERNEL);
+                               if (!sub) {
+                                       ret = -ENOMEM;
+                                       goto err;
+                               }
+                       }
+               }
+       } else {
+               if (!device_property_read_string(cs35l41->dev, "cirrus,subsystem-id", &tmp)) {
+                       sub = kstrdup(tmp, GFP_KERNEL);
+                       if (!sub) {
+                               ret = -ENOMEM;
+                               goto err;
+                       }
+               }
        }
 
-       cs35l41->dsp.system_name = sub;
-       dev_dbg(cs35l41->dev, "Subsystem ID: %s\n", cs35l41->dsp.system_name);
+err:
+       if (sub) {
+               cs35l41->dsp.system_name = sub;
+               dev_info(cs35l41->dev, "Subsystem ID: %s\n", cs35l41->dsp.system_name);
+       } else
+               dev_warn(cs35l41->dev, "Subsystem ID not found\n");
 
-       return 0;
-}
-#else
-static int cs35l41_acpi_get_name(struct cs35l41_private *cs35l41)
-{
-       return 0;
+       return ret;
 }
-#endif /* CONFIG_ACPI */
 
 int cs35l41_probe(struct cs35l41_private *cs35l41, const struct cs35l41_hw_cfg *hw_cfg)
 {
@@ -1317,7 +1328,7 @@ int cs35l41_probe(struct cs35l41_private *cs35l41, const struct cs35l41_hw_cfg *
                goto err;
        }
 
-       ret = cs35l41_acpi_get_name(cs35l41);
+       ret = cs35l41_get_system_name(cs35l41);
        if (ret < 0)
                goto err;