xavier nx平台将控制台更改为其他串口1

1. 前言

代替默认的ttyTCU0。
是否有办法将控制台端口更改为其他uart端口?
试图修改tegra194-p3668-common.dtsi和cboot源代码切换/禁用控制台uart，
并它没有影响控制台仍然来自ttyTHS0 /ttyTCU0与tegra组合uart机制。

tegra194-p3668-common.dtsi
chosen {
bootargs =“console=ttyTHS1,115200”;
board-has-eeprom;
nvidia,tegra-joint_xpu_rail;
};

2. 查询方法

Jetson Xavier NX将三个uart带出主连接器;
可以访问NX Product Design Guide，
并检查[表10-7]的引脚描述。

可以搜索由ttyUSB启用发送串行数据的串行端口，
在Ubuntu主机上检查$ ls -la /dev/ttyUSB，
并使用picocom或minicom工具连接uart日志
默认波特率设置为115200/8n1。

3. 查询设备节点& 设备树映射

可以参考内核初始消息，检查所有挂载的串行端口，

$ dmesg | grep THS

可以访问L4T sources包的公共发布源
可以检查设备树设置的映射。

$L4T_Sources/r32.4.3/Linux_for_Tegra/source/public/hardware/nvidia/soc/t19x/kernel-dts/tegra194-soc/tegra194-soc-uart.dtsi

现在使用的bsp是L4T r32.4.3
tegra194-p3668-common.dtsi中默认的uart相关设置是

serial@3100000 {
    compatible = "nvidia,tegra186-hsuart";
    status = "okay";
};

serial@3140000 {
    compatible = "nvidia,tegra186-hsuart";
    status = "okay";
};

combined-uart {
    console-port;
    combined-uart;
    status = "okay";
};`

dmesg THS设备如下

 [    1.616093] 3100000.serial: ttyTHS0 at MMIO 0x3100000 (irq = 47, base_baud = 0) is a TEGRA_UART

   [    1.617093] 3110000.serial: ttyTHS1 at MMIO 0x3110000 (irq = 48, base_baud = 0) is a TEGRA_UART

   [    1.617781] 3140000.serial: ttyTHS4 at MMIO 0x3140000 (irq = 49, base_baud = 0) is a TEGRA_UART

控制台日志从ttyTHS0实际输出
这是否意味着THS0是UART3引脚236,238
(电路板的实际控制台输出是UART1引脚203~209)

在表10-7中
THS0 THS1 THS4与uart1,uart2,uart3之间的默认相关设置映射应该是什么
它似乎不符合规格显示(控制台输出从pin236 238)

qbic-desktop login: Ubuntu 18.04.4 LTS qbic-desktop ttyTHS0

4. 分析问题

控制台日志从ttyTHS0
实际上使用pin-203/pin-205进行UART传输。

参考下面的例子，
根据设备树定义，serial@3100000注册为uart-a

aliases {
        serial0 = &uarta;
...
    uarta: serial@3100000 {
        compatible = "nvidia,tegra186-hsuart";

应该检查pinmux电子表格10或pinmux配置文件以作为参考。
例如
$OUT/Linux_for_Tegra/bootloader/tegra19x-mb1-pinmux-p3668-a01.cfg

pinmux.0x024300a8 = 0x00000400; # uart1_tx_pr2: uarta, tristate-disable, input-disable, io_high_voltage-disable, lpdr-disable
pinmux.0x024300a0 = 0x00000454; # uart1_rx_pr3: uarta, pull-down, tristate-enable, input-enable, io_high_voltage-disable, lpdr-disable

它是串行内核驱动程序在内核初始化期间注册tty设备
可以查看下面的源代码以获得更多细节。

$L4T_Sources/r32.4.3/Linux_for_Tegra/source/public/kernel/
kernel-4.9/drivers/tty/serial/serial_core.c

5. 查询结果

这些是L4T上的uart映射
tegra19x-mb1-pinmux-p3668-a01.cfg

pinmux.0x024300a8 = 0x00000400; # uart1_tx_pr2: uarta, tristate-disable, input-disable, io_high_voltage-disable, lpdr-disable
pinmux.0x024300a0 = 0x00000454; # uart1_rx_pr3: uarta, pull-down, tristate-enable, input-enable, io_high_voltage-disable, lpdr-disable
pinmux.0x02430098 = 0x00000055; # uart1_rts_pr4: rsvd1, pull-down, tristate-enable, input-enable, lpdr-disable
pinmux.0x02430090 = 0x00000055; # uart1_cts_pr5: rsvd1, pull-down, tristate-enable, input-enable, lpdr-disable
pinmux.0x0243d070 = 0x00000400; # uart2_tx_px4: uartb, tristate-disable, input-disable, io_high_voltage-disable, lpdr-disable
pinmux.0x0243d078 = 0x00000450; # uart2_rx_px5: uartb, tristate-enable, input-enable, io_high_voltage-disable, lpdr-disable
pinmux.0x0243d080 = 0x00000408; # uart2_rts_px6: uartb, pull-up, tristate-disable, input-disable, lpdr-disable
pinmux.0x0243d088 = 0x00000458; # uart2_cts_px7: uartb, pull-up, tristate-enable, input-enable, lpdr-disable
pinmux.0x0c302010 = 0x00000400; # uart3_tx_pcc5: uartc, tristate-disable, input-disable, io_high_voltage-disable, lpdr-disable
pinmux.0x0c302008 = 0x00000450; # uart3_rx_pcc6: uartc, tristate-enable, input-enable, io_high_voltage-disable, lpdr-disable

pinmux spreadsheets

UART1_TXD 203 UART1_TX GPIO3_PR.02
UART1_RXD 205 UART1_RX GPIO3_PR.03
UART1_RTS* 207 UART1_RTS GPIO3_PR.04
UART1_CTS* 209 UART1_CTS GPIO3_PR.05
UART2_TXD 236 UART3_TX GPIO3_PCC.05
UART2_RXD 238 UART3_RX GPIO3_PCC.06

tegra194-soc-uart.dtsi

serial0 = &uarta;
serial1 = &uartb;
serial2 = &uartc;

启用所有uart
log:

[    1.437891] 3100000.serial: ttyTHS0 at MMIO 0x3100000 (irq = 47, base_baud = 0) is a TEGRA_UART
[    1.439066] 3110000.serial: ttyTHS1 at MMIO 0x3110000 (irq = 48, base_baud = 0) is a TEGRA_UART
[    1.441064] c280000.serial: ttyTHS2 at MMIO 0xc280000 (irq = 49, base_baud = 0) is a TEGRA_UART
[    1.441848] 3130000.serial: ttyTHS3 at MMIO 0x3130000 (irq = 50, base_baud = 0) is a TEGRA_UART
[    1.442556] 3140000.serial: ttyTHS4 at MMIO 0x3140000 (irq = 51, base_baud = 0) is a TEGRA_UART
[    1.443210] 3150000.serial: ttyTHS5 at MMIO 0x3150000 (irq = 52, base_baud = 0) is a TEGRA_UART
[    1.444184] c290000.serial: ttyTHS6 at MMIO 0xc290000 (irq = 53, base_baud = 0) is a TEGRA_UART
[    1.444902] 3170000.serial: ttyTHS7 at MMIO 0x3170000 (irq = 54, base_baud = 0) is a TEGRA_UART

根据以上信息，
THS0 =uarta=pr2/pr3=203/205 UART1_TX UART1_RX
THS2 = uartc = pcc5 / pcc6 = 236/238 UART3_TX UART3_RX
因为载体板的引脚头设计UART3
打开终端输出消息到/dev/ttyTHS2进行测试，并使用示波器监控UART3_TX信号。(pin236)

可以用J14接线uart传输，检查" ll /dev/ttyUSB* "来设置连接。
J14 pin 3/4 = UART2_TXD,UART2_RXD /UART3_TX,UART3_RX =pin 236,238
端口映射为ttyTHS2。
HW调试后，该端口可用于一般uart使用后，kenel启动
但是bootloader和lk log是从这个端口输出的。(UART2_TXD THS2 UART2_RXD)
ttyTCU0登录控制台绑定到THS0。