SPDIFRX Linux driver
目录
Article purpose
本文介绍了适用于SPDIFRX internal peripheral的SPDIFRX Linux®驱动程序。
Short Description
SPDIFRX[1] Linux 驱动程序是在LinuxALSA framework中实现的ASoC CPU DAI驱动程序。
Configuration
Kernel Configuration
Activate the SPDIFRX[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 S/PDIF receiver (SPDIFRX) support
Device tree
Refer to the SPDIFRX device tree configuration article when configuring the SPDIFRX Linux kernel driver.
How to use
The SPDIFRX driver is accessed from userland through an ALSA device. Refer to ALSA overview to see how to list and use ALSA devices.
The SPDFIRX driver exposes an alsa control, which allows to retrieve the IEC958 status bits from the input audio stream.
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The configuration of the SPDIFRX input pin in the device tree, may put some restrictions on the use of IEC958 control. Thus, in some configuration, the control can be used only when an audio stream is captured. Refer to the SPDIFRX device tree configuration article, to find details about SPDIFRX configuration. |
How to debug
The 调试文件系统(debugfs) and procfs file systems can be checked to get information about the SPDFIRX driver and the resources it uses. A none exhaustive list of these file system entries is provided below. Refer to ALSA overview to get more details about 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 SPDIFRX 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
Source code location
sound/soc/stm/stm32_spdifrx.c| |}} sound/soc/stm/stm32_spdifrx.c : implements the SPDIFRX driver.
