CS35L41 has a DSP which is able to run firmware, as well as a tuning file. Different systems may want to use different firmwares and tuning files, and some firmwares/tunings may not be compatible with other systems. To allow a system to select the correct fimware/tuning, we can read an _SUB from the ACPI. This _SUB can then be used to uniquely identify the system in the firmware/tuning file name.
Add a helper function which reads the _SUB, so this can be used by other parts in the future. Add support inside the CS35L41 ASoC driver to read this _SUB, and save it appropriately.
Changes since v5: - Clean up return codes - Refactor length calculation - Allow fallback to existing behaviour when bad ACPI is detected
Changes since v4: - Rename function
Changes since v3: - Fix 32 bit format string warning
Changes since v2: - Fix error in function prototype
Changes since v1: - Add length validation for SSID String - Rename API - Allocate memory inside API - Use ACPI_HANDLE macro instead of ACPI_COMPANION - Improve error handling
Stefan Binding (2): ACPI: utils: Add api to read _SUB from ACPI ASoC: cs35l41: Read System Name from ACPI _SUB to identify firmware
drivers/acpi/utils.c | 38 ++++++++++++++++++++++++++++++++++++++ include/linux/acpi.h | 6 ++++++ sound/soc/codecs/cs35l41.c | 30 ++++++++++++++++++++++++++++++ 3 files changed, 74 insertions(+)