STM32MP157 Linux系統(tǒng)移植開發(fā)篇16：Linux內(nèi)核音頻驅(qū)動(dòng)移植
本文章為《STM32MP157 Linux系統(tǒng)移植開發(fā)篇》系列中的一篇，筆者使用的開發(fā)平臺(tái)為華清遠(yuǎn)見FS-MP1A開發(fā)板（STM32MP157開發(fā)板）。stm32mp157是ARM雙核，2個(gè)A7核，1個(gè)M4核，A7核上可以跑Linux操作系統(tǒng)，M4核上可以跑FreeRTOS、RT-Thread等實(shí)時(shí)操作系統(tǒng)，STM32MP157開發(fā)板所以既可以學(xué)嵌入式linux，也可以學(xué)stm32單片機(jī)。
針對(duì)FS-MP1A開發(fā)板，除了Linux系統(tǒng)移植篇外，還包括其他多系列教程，包括Cortex-A7開發(fā)篇、Cortex-M4開發(fā)篇、擴(kuò)展板驅(qū)動(dòng)移植篇、Linux應(yīng)用開發(fā)篇、FreeRTOS系統(tǒng)移植篇、Linux驅(qū)動(dòng)開發(fā)篇、硬件設(shè)計(jì)篇、人工智能機(jī)器視覺篇、Qt應(yīng)用編程篇、Qt綜合項(xiàng)目實(shí)戰(zhàn)篇等。歡迎關(guān)注，更多stm32mp157開發(fā)教程及視頻，可加技術(shù)交流Q群459754978，感謝關(guān)注。
關(guān)于FS-MP1A開發(fā)板：
手機(jī)淘寶分享碼：復(fù)制本行文字打開手淘?T4FPXn3YYJ2?
鏈接：https://item.taobao.com/item.htm?id=622457259672
1.實(shí)驗(yàn)原理
FS-MP1A使用的是CS42L51音頻芯片，SoC通過I2C和SAI與其進(jìn)行數(shù)據(jù)交互，原理圖如下：
SAI2管腳對(duì)應(yīng)關(guān)系：
I2C5管腳對(duì)應(yīng)關(guān)系：
芯片復(fù)位管腳對(duì)應(yīng)關(guān)系：
原理圖網(wǎng)絡(luò)編號(hào)對(duì)應(yīng)管腳管腳功能管腳功能碼SAI2_MCLKAPE0SAI2_MCLK_AAF10SAI2_SDBPF11SDA2_SD_BAF10SAI2_SCKAPI5SAI2_SCK_AAF10SAI_SDAPI6SAI2_SD_AAF10SAI2_FSAPI7SAI2_FS_AAF10AUDIO_RSTPC0IOANALOGI2C5_SDAPA11I2C5_SDAAF4I2C5_SCLPA12I2C5_SDAAF4
SAI2設(shè)備樹節(jié)點(diǎn)
參考文檔：
Documentation/devicetree/bindings/sound/st,stm32-sai.txt
內(nèi)核中ST對(duì)STM32MP15x系列芯片的設(shè)備樹資源了做了定義，可參見：
sai2: sai@4400b000 {
compatible = "st,stm32h7-sai";
#address-cells = <1>;
#size-cells = <1>;
ranges = <0 0x4400b000 0x400>;
reg = <0x4400b000 0x4>, <0x4400b3f0 0x10>;
interrupts = <GIC_SPI 91 IRQ_TYPE_LEVEL_HIGH>;
resets = <&rcc SAI2_R>;
status = "disabled";
sai2a: audio-controller@4400b004 {
#sound-dai-cells = <0>;
compatible = "st,stm32-sai-sub-a";
reg = <0x4 0x1c>;
clocks = <&rcc SAI2_K>;
clock-names = "sai_ck";
dmas = <&dmamux1 89 0x400 0x01>;
status = "disabled";
};
sai2b: audio-controller@4400b024 {
#sound-dai-cells = <0>;
compatible = "st,stm32-sai-sub-b";
reg = <0x24 0x1c>;
clocks = <&rcc SAI2_K>;
clock-names = "sai_ck";
dmas = <&dmamux1 90 0x400 0x01>;
status = "disabled";
};
};
上述代碼只對(duì)SAI2做了基本的初始化，并沒有針對(duì)不同的硬件設(shè)計(jì)做適配，所以需結(jié)合硬件補(bǔ)全設(shè)備樹節(jié)點(diǎn)信息。
參考stm32mp15xx-dkx.dtsi對(duì)于SAI2設(shè)備節(jié)點(diǎn)的描述，增加SAI2內(nèi)容如下：
&sai2 {
clocks = <&rcc SAI2>, <&rcc PLL3_Q>, <&rcc PLL3_R>;
clock-names = "pclk", "x8k", "x11k";
pinctrl-names = "default", "sleep";
pinctrl-0 = <&sai2a_pins_a>, <&sai2b_pins_b>;
pinctrl-1 = <&sai2a_sleep_pins_a>, <&sai2b_sleep_pins_b>;
status = "okay";
sai2a: audio-controller@4400b004 {
#clock-cells = <0>;
dma-names = "tx";
clocks = <&rcc SAI2_K>;
clock-names = "sai_ck";
status = "okay";
sai2a_port: port {
sai2a_endpoint: endpoint {
remote-endpoint = <&cs42l51_tx_endpoint>;
format = "i2s";
mclk-fs = <256>;
dai-tdm-slot-num = <2>;
dai-tdm-slot-width = <32>;
};
};
};
sai2b: audio-controller@4400b024 {
dma-names = "rx";
st,sync = <&sai2a 2>;
clocks = <&rcc SAI2_K>, <&sai2a>;
clock-names = "sai_ck", "MCLK";
status = "okay";
sai2b_port: port {
sai2b_endpoint: endpoint {
remote-endpoint = <&cs42l51_rx_endpoint>;
format = "i2s";
mclk-fs = <256>;
dai-tdm-slot-num = <2>;
dai-tdm-slot-width = <32>;
};
};
};
};
由于stm32mp15-pinctrl.dtsi中對(duì)于SAI2管腳的定義與FS-MP1A實(shí)際使用管腳一致，所以無需修改。
CS42L51設(shè)備樹節(jié)點(diǎn)
由于前文中已經(jīng)增加過I2C5的節(jié)點(diǎn)信息，本節(jié)就不再重復(fù)，在原有I2C5節(jié)點(diǎn)添加CS42L51內(nèi)容即可。
參考文檔：
Documentation/devicetree/bindings/sound/cs42l51.txt
參考stm32mp15xx-dkx.dtsi對(duì)于codec芯片設(shè)備節(jié)點(diǎn)的描述，增加內(nèi)容如下：
cs42l51: cs42l51@4a {
compatible = "cirrus,cs42l51";
reg = <0x4a>;
#sound-dai-cells = <0>;
VL-supply = <&v3v3>;
VD-supply = <&v1v8_audio>;
VA-supply = <&v1v8_audio>;
VAHP-supply = <&v1v8_audio>;
reset-gpios = <&gpioc 0 GPIO_ACTIVE_LOW>;
clocks = <&sai2a>;
clock-names = "MCLK";
status = "okay";
cs42l51_port: port {
#address-cells = <1>;
#size-cells = <0>;
cs42l51_tx_endpoint: endpoint@0 {
reg = <0>;
remote-endpoint = <&sai2a_endpoint>;
frame-master;
bitclock-master;
};
cs42l51_rx_endpoint: endpoint@1 {
reg = <1>;
remote-endpoint = <&sai2b_endpoint>;
frame-master;
bitclock-master;
};
};
};
1.8V電源設(shè)備節(jié)點(diǎn)
前文已經(jīng)說過如何添加電源節(jié)點(diǎn)，本節(jié)不再重復(fù)，在根節(jié)點(diǎn)添加&v1v8_audio節(jié)點(diǎn)，內(nèi)容如下：
v1v8_audio: regulator-v1v8_audio {
compatible = "regulator-fixed";
regulator-name = "v1v8_audio";
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
regulator-always-on;
regulator-boot-on;
};
SOC聲卡驅(qū)動(dòng)節(jié)點(diǎn)
內(nèi)核中包含audio-graph-card驅(qū)動(dòng)，驅(qū)動(dòng)將聲卡各個(gè)部分關(guān)聯(lián)起來，驅(qū)動(dòng)正常工作需添加對(duì)應(yīng)設(shè)備樹節(jié)點(diǎn)。
參考文檔：
Documentation/devicetree/bindings/sound/audio-graph-card.txt
在根節(jié)點(diǎn)寫下添加sound節(jié)點(diǎn)：
sound {
compatible = "audio-graph-card";
label = "STM32MP1-FSMP1A";
routing =
"Playback" , "MCLK",
"Capture" , "MCLK",
"MICL" , "Mic Bias";
dais = <&sai2a_port &sai2b_port>;
status = "okay";
};
2.實(shí)驗(yàn)平臺(tái)
華清遠(yuǎn)見開發(fā)環(huán)境，F(xiàn)S-MP1A平臺(tái)；
3.實(shí)驗(yàn)?zāi)康?/h1>
熟悉基于Linux操作系統(tǒng)下的音頻設(shè)備驅(qū)動(dòng)移植配置過程。
4.實(shí)驗(yàn)步驟
導(dǎo)入交叉編譯工具鏈
linux@ubuntu:$ source /opt/st/stm32mp1/3.1-openstlinux-5.4-dunfell-mp1-20-06-24/environment-setup-cortexa7t2hf-neon-vfpv4-ostl-linux-gnueabi
添加SAI2節(jié)點(diǎn)
修改arch/arm/boot/dts/stm32mp15xx-fsmp1x.dtsi文件，在文件末尾添加如下內(nèi)容：
&sai2 {
clocks = <&rcc SAI2>, <&rcc PLL3_Q>, <&rcc PLL3_R>;
clock-names = "pclk", "x8k", "x11k";
pinctrl-names = "default", "sleep";
pinctrl-0 = <&sai2a_pins_a>, <&sai2b_pins_b>;
pinctrl-1 = <&sai2a_sleep_pins_a>, <&sai2b_sleep_pins_b>;
status = "okay";
sai2a: audio-controller@4400b004 {
#clock-cells = <0>;
dma-names = "tx";
clocks = <&rcc SAI2_K>;
clock-names = "sai_ck";
status = "okay";
sai2a_port: port {
sai2a_endpoint: endpoint {
remote-endpoint = <&cs42l51_tx_endpoint>;
format = "i2s";
mclk-fs = <256>;
dai-tdm-slot-num = <2>;
dai-tdm-slot-width = <32>;
};
};
};
sai2b: audio-controller@4400b024 {
dma-names = "rx";
st,sync = <&sai2a 2>;
clocks = <&rcc SAI2_K>, <&sai2a>;
clock-names = "sai_ck", "MCLK";
status = "okay";
sai2b_port: port {
sai2b_endpoint: endpoint {
remote-endpoint = <&cs42l51_rx_endpoint>;
format = "i2s";
mclk-fs = <256>;
dai-tdm-slot-num = <2>;
dai-tdm-slot-width = <32>;
};
};
};
};
添加CS42L51節(jié)點(diǎn)
修改arch/arm/boot/dts/stm32mp15xx-fsmp1x.dtsi文件，在I2C5節(jié)點(diǎn)中添加如下內(nèi)容：
cs42l51: cs42l51@4a {
compatible = "cirrus,cs42l51";
reg = <0x4a>;
#sound-dai-cells = <0>;
VL-supply = <&v3v3>;
VD-supply = <&v1v8_audio>;
VA-supply = <&v1v8_audio>;
VAHP-supply = <&v1v8_audio>;
reset-gpios = <&gpioc 0 GPIO_ACTIVE_LOW>;
clocks = <&sai2a>;
clock-names = "MCLK";
status = "okay";
cs42l51_port: port {
#address-cells = <1>;
#size-cells = <0>;
cs42l51_tx_endpoint: endpoint@0 {
reg = <0>;
remote-endpoint = <&sai2a_endpoint>;
frame-master;
bitclock-master;
};
cs42l51_rx_endpoint: endpoint@1 {
reg = <1>;
remote-endpoint = <&sai2b_endpoint>;
frame-master;
bitclock-master;
};
};
};
添加v1v8_audio電源節(jié)點(diǎn)
修改arch/arm/boot/dts/stm32mp15xx-fsmp1x.dtsi文件，在根節(jié)點(diǎn)中添加如下內(nèi)容：
v1v8_audio: regulator-v1v8_audio {
compatible = "regulator-fixed";
regulator-name = "v1v8_audio";
regulator-min-microvolt = <1800000>;
regulator-max-microvolt = <1800000>;
regulator-always-on;
regulator-boot-on;
};
添加Sound節(jié)點(diǎn)
修改arch/arm/boot/dts/stm32mp15xx-fsmp1x.dtsi文件，在根節(jié)點(diǎn)中添加如下內(nèi)容：
sound {
compatible = "audio-graph-card";
label = "STM32MP1-FSMP1A";
routing =
"Playback" , "MCLK",
"Capture" , "MCLK",
"MICL" , "Mic Bias";
dais = <&sai2a_port &sai2b_port>;
status = "okay";
};
配置內(nèi)核
由于內(nèi)核源碼默認(rèn)配置以及支持CS42L51，本節(jié)列出主要選項(xiàng)，如下：
linux@ubuntu:$ make menuconfig
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
CODEC drivers --->
<*> Cirrus Logic CS42L51 CODEC (I2C)
<*> ASoC Audio Graph sound card support
編譯內(nèi)核及設(shè)備樹
linux@ubuntu:$ make -j4 uImage dtbs LOADADDR=0xC2000040
重啟測(cè)試
將編譯好的設(shè)備樹和內(nèi)核鏡像拷貝到/tftpboot目錄下，通過tftp引導(dǎo)內(nèi)核，啟動(dòng)后啟動(dòng)信息中出現(xiàn)如下內(nèi)容：
插上耳機(jī)，終端輸入錄音命令：
root@fsmp1a:# arecord -D record_codec -f S16_LE -d 10 test.wav
終端輸入播放命令：
root@fsmp1a:# aplay test.wav
注意：由于3.5mm的4段式耳機(jī)接口還分為兩種，一種是美標(biāo)版（CTIA），也稱為“蘋果標(biāo)準(zhǔn)”，同時(shí)小米、魅族也是使用這種標(biāo)準(zhǔn)；另外一種是國(guó)標(biāo)版（OMTP），也稱為“諾基亞標(biāo)準(zhǔn)”，現(xiàn)在絕大多數(shù)諾基亞和大多數(shù)國(guó)產(chǎn)手機(jī)都是使用這種標(biāo)準(zhǔn)。FS-MP1A使用的是國(guó)標(biāo)版，所以部分耳機(jī)并不能正常實(shí)現(xiàn)錄播功能。
硬件平臺(tái)：華清遠(yuǎn)見FS-MP1A開發(fā)板（STM32MP157）
部分開發(fā)教程下載：加QQ群459754978，群文件里有。
淘寶購(gòu)買鏈接：https://item.taobao.com/item.htm?id=622457259672
手機(jī)淘寶分享碼：復(fù)制本行文字打開手淘?T4FPXn3YYJ2?
