RockchipUART (Universal Asynchronous Receiver/Transmitter) 基于16550A串口标准,完整模块支持以下功能:
(资料图片仅供参考)
支持5、6、7、8 bits数据位。支持【chí】1、1.5、2 bits停【tíng】止位【wèi】。支持奇校验和偶校验,不支持【chí】mark校验【yàn】和space校验。支持接收【shōu】FIFO和发送FIFO,一般为32字节或者64字节。支【zhī】持最【zuì】高4M波特【tè】率,实际支【zhī】持波特率【lǜ】需要【yào】芯片时钟分频策略配合。支持中断传输模式和DMA传输模式。 支持硬件自动流控,RTS+CTS。在Linuxkernel 中,使【shǐ】用8250串口【kǒu】通用【yòng】驱动,以下为主要驱【qū】动文件:
drivers/tty/serial/8250/8250_core.c # 8250串口驱【qū】动核【hé】心
drivers/tty/serial/8250/8250_dw.c # Synopsis DesignWare 8250串口驱动
drivers/tty/serial/8250/8250_dma.c # 8250串【chuàn】口【kǒu】DMA驱动
drivers/tty/serial/8250/8250_port.c # 8250串【chuàn】口端口【kǒu】操作
drivers/tty/serial/8250/8250_early.c # 8250串【chuàn】口【kǒu】early console驱动
SDK中提供的【de】UART默认配置已【yǐ】经使用了【le】8250驱动我们【men】就不需要修改
串口功能的硬件上比较简单,这是只附上调试串口的原理图
rk平台的设备树修改路径都是在kernel\\arch\\arm64\\boot\\dts\\rockchip下面,具体哪个文件根【gēn】据【jù】对应【yīng】开发【fā】板来决定,通常【cháng】描述设备硬件配置【zhì】在【zài】rkxxxx.dtsi中,比【bǐ】如在rk3588s.dtsi中:
uart2: serial@feb50000 {compatible = "rockchip,rk3588-uart", "snps,dw-apb-uart";reg = < 0x0 0xfeb50000 0x0 0x100 >;interrupts = < GIC_SPI 333 IRQ_TYPE_LEVEL_HIGH >;clocks = < &cru SCLK_UART2 >, < &cru PCLK_UART2 >;clock-names = "baudclk", "apb_pclk";reg-shift = < 2 >;reg-io-width = < 4 >;dmas = < &dmac0 10 >, < &dmac0 11 >;pinctrl-names = "default";pinctrl-0 = < &uart2m1_xfer >;status = "disabled";};
假入我们想使用w3开发板上40PIN上的uart7
我们在dts可以使用如下配置打开
&uart7 {status = "okay";pinctrl-names = "default";pinctrl-0 = < &uart7m1_xfer >;};
Rockchip UART作为控制【zhì】台,使【shǐ】用fiq_debugger流【liú】程。
在dts中fiq_debugger节点配置【zhì】如下【xià】。由于fiq_debugger和普【pǔ】通串口互斥,在使能【néng】fiq_debugger节点后必须【xū】禁用对【duì】应的普【pǔ】通串口uart节点。
chosen: chosen {bootargs = "earlycon=uart8250,mmio32,0xfe660000 console=ttyFIQ0";};fiq-debugger {compatible = "rockchip,fiq-debugger";rockchip,serial-id = < 2 >;rockchip,wake-irq = < 0 >;/* If enable uart uses irq insteadof fiq */rockchip,irq-mode-enable = < 1 >;rockchip,baudrate = < 1500000 >; /* Only 115200 and 1500000 */interrupts = < GIC_SPI 252 IRQ_TYPE_LEVEL_LOW >;pinctrl-names = "default";pinctrl-0 = < &uart2m0_xfer >;status = "okay";};&uart2 {status = "disabled";};
rockchip,serial-id:使用【yòng】的UART编号。修改serial-id到不【bú】同UART,fiq_debugger设备也会注册【cè】成【chéng】ttyFIQ0设备。 rockchip,irq-mode-enable:配置为1使【shǐ】用irq中断,配置为0使用【yòng】fiq中断。interrupts:配置【zhì】的【de】辅助中断【duàn】,保持【chí】默认即可。pinctrl-0:使用的【de】串口引【yǐn】脚rockchip,baudrate:波特率配置普通串口设备将会根据dts中的aliase来对串口进【jìn】行【háng】编号【hào】,对应注册成ttySx设备。注册的节点为/dev/ttyS4,命名规则【zé】是通【tōng】过【guò】dts中的aliases来【lái】的。
aliases {serial0 = &uart0;serial1 = &uart1;serial2 = &uart2;serial3 = &uart3;}
对应uart0注册为【wéi】ttyS0,uart0注册为【wéi】ttyS1,如果需要把uart3注册成【chéng】ttyS1,可以进行以下【xià】修【xiū】改
serial1 = &uart3; serial3 = &uart1;
Rockchip UART打印通常【cháng】包括DDR阶段、Miniloader阶段【duàn】、TF-A (Trusted Firmware-A)阶段、OP-TEE阶【jiē】段【duàn】、Uboot阶段【duàn】和Kernel阶段,我们平时【shí】主要关注【zhù】的是【shì】uboot阶段和kernel阶段的打印,在这【zhè】两个阶【jiē】段【duàn】我们【men】可以尝试关闭所有打印【yìn】或切换【huàn】所有打印到其他UART,RK平【píng】台默认的调试串口是【shì】uart2_m0这一组引脚【jiǎo】,假如现在我将打印【yìn】换成其他串口,可以尝试【shì】以【yǐ】下做法。
DDR Loader中关闭或切换打【dǎ】印,需【xū】要修改DDR Loader中【zhōng】的UART打印配置,修改文件rkbin/tools/ddrbin_param.txt中的以下参数:
uart id= # UART控制【zhì】器id,配置为0xf为关【guān】闭打印
uart iomux= # 复用的IOMUX引脚 uart
baudrate= # 115200 or 1500000
修改完成后,使用以下命令重新生成ddr.bin固件。
./ddrbin_tool ddrbin_param.txt rk3588_ddr_lp4_2112MHz_lp5_2736MHz_v1.09.bin
Uboot中关闭【bì】打印【yìn】,需要在【zài】menuconfig中【zhōng】,打开配CONFIG_DISABLE_CONSOLE,保存到【dào】.config文件
Uboot中【zhōng】切换打印,由传参机制决定,不需要进行额【é】外修改。uboot解析传参机制相关代码【mǎ】在arch/arm/mach-rockchip/board.c的board_init_f_init_serial()函数【shù】中。
去【qù】掉打印需要【yào】在menuconfig中,关闭配置CONFIG_SERIAL_8250_CONSOLE。
Device Drivers --->
Character devices --->
Serial drivers --->
[ ]Console on 8250/16550 and compatible serial port
在dts配置中【zhōng】找【zhǎo】到类似以【yǐ】下内容【róng】,并去掉【diào】UART基地址和console相关配置【zhì】参数
chosen: chosen {bootargs = "earlycon=uart8250,mmio32,0xfeb50000 console=ttyFIQ0 irqchip.gicv3_pseudo_nmi=0 root=PARTUUID=614e0000-0000 rw rootwait";};
将0xfeb50000 console=ttyFIQ0 去掉,然后找【zhǎo】到fiq-debugger节点,修【xiū】改serial-id为0xffffffff,去【qù】掉UART引【yǐn】脚复用相关配置。注【zhù】意【yì】,需要保持fiqdebugger节点【diǎn】使能,保持【chí】fiq-debugger流程系统才能正常【cháng】启动
fiq_debugger: fiq-debugger {compatible = "rockchip,fiq-debugger";rockchip,serial-id = < 0xffffffff >;rockchip,wake-irq = < 0 >;/* If enable uart uses irq instead of fiq */rockchip,irq-mode-enable = < 1 >;rockchip,baudrate = < 1500000 >; /* Only 115200 and 1500000 */interrupts = < GIC_SPI 423 IRQ_TYPE_LEVEL_LOW >;status = "okay";};
切换打印串【chuàn】口例【lì】如将Kernel打印从UART2切【qiē】换到UART3,在【zài】dts配置中找到类似【sì】以下内容,将UART基地址由UART2改【gǎi】为【wéi】UART3.
bootargs = "earlycon=uart8250,mmio32,0xfe670000 console=ttyFIQ0";
0xfe670000是UART3基地址,然后【hòu】找【zhǎo】到fiq-debugger节点,修改serial-id为3,修改UART3引脚【jiǎo】复用配置pinctrl-0 = <&uart3m0_xfer>。注意,同【tóng】时需要将切换【huàn】为打印【yìn】串口的UART3作为普通串【chuàn】口的【de】节点禁【jìn】用。
在开发【fā】板上跑【pǎo】一套【tào】应【yīng】用程序,可以发送【sòng】数据【jù】,可以接收数据,测试方法可以短接TX_RX
#include < stdio.h >#include < stdlib.h >#include < errno.h >#include < unistd.h >#include < fcntl.h >#include < string.h >#include < termio.h >#include < time.h >#include < pthread.h >int read_data(int fd, void *buf, int len);int write_data(int fd, void *buf, int len);int setup_port(int fd, int baud, int databits, int parity, int stopbits);void print_usage(char *program_name);pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;pthread_cond_t data_ready = PTHREAD_COND_INITIALIZER;int data_available = 0;void *read_thread(void *arg) { int fd = *(int *)arg; char buffer[1024]; // 存储读取的数据 while (1) { int bytes_read = read_data(fd, buffer, sizeof(buffer)); if (bytes_read > 0) { printf("Read Thread: Read %d bytes: %s\\n", bytes_read, buffer); } else { // 处理读【dú】取【qǔ】错误或设备关闭【bì】的【de】情况 break; } } pthread_exit(NULL);}void *write_thread(void *arg) { int fd = *(int *)arg;char input[1024]; // 存储【chǔ】用【yòng】户输入的数据【jù】 while (1) { printf("Enter data to write (or "q" to quit): "); fgets(input, sizeof(input), stdin); if (strcmp(input, "q\\n") == 0 || strcmp(input, "Q\\n") == 0) { // 用户输入 "q" 或 "Q",退出循环 break; } int len = strlen(input); int bytes_written = write_data(fd, input, len); if (bytes_written > 0) { printf("Write Thread: Wrote %d bytes: %s\\n", bytes_written, input); } } pthread_exit(NULL);}int main(int argc, char *argv[]) //./a.out /dev/ttyS4 115200 8 0 1{ int fd; int baud; int len; int count; int i; int databits; int stopbits; int parity; if (argc != 6) { print_usage(argv[0]); return 1; } baud = atoi(argv[2]); if ((baud < 0) || (baud > 921600)) { fprintf(stderr, "Invalid baudrate!\\n"); return 1; } databits = atoi(argv[3]); if ((databits < 5) || (databits > 8)) { fprintf(stderr, "Invalid databits!\\n"); return 1; } parity = atoi(argv[4]); if ((parity < 0) || (parity > 2)) { fprintf(stderr, "Invalid parity!\\n"); return 1; } stopbits = atoi(argv[5]); if ((stopbits < 1) || (stopbits > 2)) { fprintf(stderr, "Invalid stopbits!\\n"); return 1; } fd = open(argv[1], O_RDWR, 0); if (fd < 0) { fprintf(stderr, "open < %s > error %s\\n", argv[1], strerror(errno)); return 1; } if (setup_port(fd, baud, databits, parity, stopbits)) { fprintf(stderr, "setup_port error %s\\n", strerror(errno)); close(fd); return 1; }pthread_t read_tid, write_tid; int ret; // 创建读【dú】取线【xiàn】程 ret = pthread_create(&read_tid, NULL, read_thread, &fd); if (ret != 0) { fprintf(stderr, "Failed to create read thread\\n"); return 1; } // 创建【jiàn】写【xiě】入线程【chéng】 ret = pthread_create(&write_tid, NULL, write_thread, &fd); if (ret != 0) { fprintf(stderr, "Failed to create write thread\\n"); return 1; } // 等待读取线程【chéng】和写入线程结束 pthread_join(read_tid, NULL); pthread_join(write_tid, NULL); close(fd); return 0;}static int baudflag_arr[] = { B921600, B460800, B230400, B115200, B57600, B38400, B19200, B9600, B4800, B2400, B1800, B1200, B600, B300, B150, B110, B75, B50};static int speed_arr[] = { 921600, 460800, 230400, 115200, 57600, 38400, 19200, 9600, 4800, 2400, 1800, 1200, 600, 300, 150, 110, 75, 50};int speed_to_flag(int speed){ int i; for (i = 0; i < sizeof(speed_arr)/sizeof(int); i++) { if (speed == speed_arr[i]) { return baudflag_arr[i]; } } fprintf(stderr, "Unsupported baudrate, use 9600 instead!\\n"); return B9600;}static struct termio oterm_attr;int setup_port(int fd, int baud, int databits, int parity, int stopbits){ struct termio term_attr; if (ioctl(fd, TCGETA, &term_attr) < 0) { return -1; } memcpy(&oterm_attr, &term_attr, sizeof(struct termio)); term_attr.c_iflag &= ~(INLCR | IGNCR | ICRNL | ISTRIP); term_attr.c_oflag &= ~(OPOST | ONLCR | OCRNL); term_attr.c_lflag &= ~(ISIG | ECHO | ICANON | NOFLSH); term_attr.c_cflag &= ~CBAUD; term_attr.c_cflag |= CREAD | speed_to_flag(baud); term_attr.c_cflag &= ~(CSIZE); switch (databits) { case 5: term_attr.c_cflag |= CS5; break; case 6: term_attr.c_cflag |= CS6; break; case 7: term_attr.c_cflag |= CS7; break; case 8: default: term_attr.c_cflag |= CS8; break; } switch (parity) { case 1: term_attr.c_cflag |= (PARENB | PARODD); break; case 2: term_attr.c_cflag |= PARENB; term_attr.c_cflag &= ~(PARODD); break; case 0: default: term_attr.c_cflag &= ~(PARENB); break; } switch (stopbits) { case 2: term_attr.c_cflag |= CSTOPB; break; case 1: default: term_attr.c_cflag &= ~CSTOPB; break; } term_attr.c_cc[VMIN] = 1; term_attr.c_cc[VTIME] = 0; if (ioctl(fd, TCSETAW, &term_attr) < 0) { return -1; } if (ioctl(fd, TCFLSH, 2) < 0) { return -1; } return 0;} int read_data(int fd, void *buf, int len){ int count; int ret; ret = 0; count = 0; //while (len > 0) { ret = read(fd, (char*)buf + count, len); if (ret < 1) { fprintf(stderr, "Read error %s\\n", strerror(errno)); //break; } count += ret; len = len - ret; //} *((char*)buf + count) = 0; return count;} int write_data(int fd, void *buf, int len){ int count; int ret; ret = 0; count = 0; while (len > 0) { ret = write(fd, (char*)buf + count, len); if (ret < 1) { fprintf(stderr, "Write error %s\\n", strerror(errno)); break; } count += ret; len = len - ret; } return count;}void print_usage(char *program_name){ fprintf(stderr, "*************************************\\n" " A Simple Serial Port Test Utility\\n" "*************************************\\n\\n" "Usage:\\n %s < device > < baud > < databits > < parity > < stopbits > \\n" " databits: 5, 6, 7, 8\\n" " parity: 0(None), 1(Odd), 2(Even)\\n" " stopbits: 1, 2\\n" "Example:\\n %s /dev/ttyS4 115200 8 0 1\\n\\n", program_name, program_name );}
运行效果如下:
审核编辑:汤梓红