SAI Linux driver

This message will disappear after all relevant tasks have been resolved.

Semantic MediaWiki

There are 1 incomplete or pending task to finish installation of Semantic MediaWiki. An administrator or user with sufficient rights can complete it. This should be done before adding new data to avoid inconsistencies.

The printable version is no longer supported and may have rendering errors. Please update your browser bookmarks and please use the default browser print function instead.

1 Article purpose[edit source]

This article introduces the SAI Linux^® driver for the SAI internal peripheral.

2 Short Description[edit source]

The SAI^[1] Linux driver is an ASoC CPU DAI driver implemented in the Linux ALSA framework.

3 Configuration[edit source]

3.1 Kernel Configuration[edit source]

Activate the SAI^[1] Linux driver in the kernel configuration using the Linux Menuconfig tool: Menuconfig or how to configure kernel.

[*] Device Drivers
    [*] Sound card support
        [*] Advanced Linux Sound Architecture
            [*] ALSA for SoC audio support
                STMicroelectronics STM32 SOC audio support
	             [*] STM32 SAI interface (Serial Audio Interface) support

3.2 Device tree[edit source]

Refer to the SAI device tree configuration article when configuring the SAI Linux kernel driver.

4 How to use[edit source]

The SAI Linux driver can be accessed from userland through an ALSA device. Refer to ALSA overview for information on how to list and use ALSA devices.

5 How to trace and debug[edit source]

The debugfs and procfs file system can be checked to get information on the SAI driver and the resources it uses. A non-exhaustive list of these file system entries is provided below. Refer to ALSA overview for more details on debugging tools.

debugfs entries:

asoc: refer to ALSA_overview#How_to_monitor
clk: refer to Clock_overview#How_to_monitor_with_debugfs to get information on clocks.
pinctrl: refer to Pinctrl_overview#How_to_monitor to get information on pins.
regmap: allow to monitor SAI peripheral registers.

$ cat /sys/kernel/debug/regmap/xxx.audio-controller/registers

procfs entries:

asound: refer to ALSA_overview#How_to_debug
interrupts: allow to check interrupts.

$ cat /proc/interrupts

6 Source code location[edit source]

The STM32 SAI peripheral includes two independent audio subblocks that share common resources. The driver source code reflects this architecture.

sound/soc/stm/stm32_sai.c : handles common resources such as clock, interrupt, reset and shared register.

sound/soc/stm/stm32_sai_sub.c : handles the resources dedicated to each subblock.

7 References[edit source]

↑ ^1.0 ^1.1 SAI internal peripheral

[SAI_internal_peripheral-1] 1.0 ^1.1 SAI internal peripheral

[1]