[置顶] 高通平台串口调试 AP与模块串口通讯调试总结

1:检查AP端串口配置是否ok：

a:高通平台查看DMA传输:

echo 1 > /sys/kernel/debug/msm_serial_hsl/loopback.0 //打开回环开关

adb shell cat /dev/ttyHSL1

另起窗口

# adb shell

# echo 11111111 > /dev/ttyHSL1

若DMA通道ok，控制台会循环显示；

b：查看uart gpio是否ok：

tx高电平、rfr为低电平，rx,cts为输入;       

如果tx为低电平，那么gpio肯定没有配置好，再次检查gpio配置问题；

如果以上2步都ok，那么UART应该ok了，再次检查：

adb shell cat /dev/ttyHSL1

将TX与RX短接；

另起窗口

# adb shell

# echo 11111111 > /dev/ttyHSL1

循环显示那么恭喜UART功能配置好了。

2：Termios参数配置：

影响通讯数据格式的关键

几个参数：

1：波特率-speed，通常

115200,最高4M；

2：奇偶校验-Parity，通

常为None；

3：数据位-Data,通常

8bit;

4：停止位-Stopbits,通

常1bit;

一般情况下默认为115200 8N1，也就是波特率115200，8bit数据位，无奇偶校验,1bit停止位。

为了使得AP可以与模块串口通讯，必须先了解模块的termios设置。

Ap端termios设置：

首先应用打开串口时会设置termios:

termios.c_cflag &= ~CSIZE;
termios.c_cflag |= CS8;
termios.c_cflag &= ~CSTOPB;
termios.c_cflag &= ~PARENB;
termios.c_cflag &= ~CBAUD;
termios.c_cflag |= B3000000; 
termios.c_cflag |= CREAD | CLOCAL;
termios.c_cflag |= CRTSCTS; /* turn on hardware flow control */
termios.c_iflag &= ~(IXOFF | IXON | IXANY); /* soft flow control */

驱动接口会根据termios参数来设置底层串口：

以8064 msm_seriel_hs.c为例说明:

uart接口封装：

static struct uart_ops msm_hs_ops = {
.tx_empty = msm_hs_tx_empty,
.set_mctrl = msm_hs_set_mctrl_locked,
.get_mctrl = msm_hs_get_mctrl_locked,
.stop_tx = msm_hs_stop_tx_locked,
.start_tx = msm_hs_start_tx_locked,
.stop_rx = msm_hs_stop_rx_locked,
.enable_ms = msm_hs_enable_ms_locked,
.break_ctl = msm_hs_break_ctl,
.startup = msm_hs_startup,
.shutdown = msm_hs_shutdown,
.set_termios = msm_hs_set_termios,
.type = msm_hs_type,
.config_port = msm_hs_config_port,
.release_port = msm_hs_release_port,
.request_port = msm_hs_request_port,
.flush_buffer = msm_hs_flush_buffer_locked,
};

下面是底层设置函数，上层打开串口，参数未固定的话驱动走的是8N1，底层调试只使用echo或者cat /dev/ttyHSL0时

波特率一律是9600,模块不是9600时那么通讯肯定会失败，所以AP需要根据模块重新设定。

波特率。

//设置termios接口

/*
* termios : new ktermios
* oldtermios: old ktermios previous setting
*
* Configure the serial port
*/
static void msm_hs_set_termios(struct uart_port *uport,
struct ktermios *termios,
struct ktermios *oldtermios)
{
unsigned int bps;
unsigned long data;
unsigned long flags;
int ret;
unsigned int c_cflag = termios->c_cflag;
struct msm_hs_port *msm_uport = UARTDM_TO_MSM(uport);
mutex_lock(&msm_uport->clk_mutex);
spin_lock_irqsave(&uport->lock, flags);
/*
* Disable Rx channel of UARTDM
* DMA Rx Stall happens if enqueue and flush of Rx command happens
* concurrently. Hence before changing the baud rate/protocol
* configuration and sending flush command to ADM, disable the Rx
* channel of UARTDM.
* Note: should not reset the receiver here immediately as it is not
* suggested to do disable/reset or reset/disable at the same time.
*/
data = msm_hs_read(uport, UARTDM_DMEN_ADDR);
data &= ~UARTDM_RX_DM_EN_BMSK;
msm_hs_write(uport, UARTDM_DMEN_ADDR, data);
/* 300 is the minimum baud support by the driver */
bps = uart_get_baud_rate(uport, termios, oldtermios, 200, 4000000);
/* Temporary remapping 200 BAUD to 3.2 mbps */
if (bps == 200)
bps = 3200000;
uport->uartclk = clk_get_rate(msm_uport->clk);
if (!uport->uartclk)
msm_hs_set_std_bps_locked(uport, bps);
else
flags = msm_hs_set_bps_locked(uport, bps, flags);//函数里面设置baud;
data = msm_hs_read(uport, UARTDM_MR2_ADDR);
data &= ~UARTDM_MR2_PARITY_MODE_BMSK;
/* set parity */ //设置奇偶校验
if (PARENB == (c_cflag & PARENB)) {
if (PARODD == (c_cflag & PARODD)) {
data |= ODD_PARITY;
} else if (CMSPAR == (c_cflag & CMSPAR)) {
data |= SPACE_PARITY;
} else {
data |= EVEN_PARITY;
}
}
/* Set bits per char */       //设置数据位
data &= ~UARTDM_MR2_BITS_PER_CHAR_BMSK;
switch (c_cflag & CSIZE) {
case CS5:
data |= FIVE_BPC;
break;
case CS6:
data |= SIX_BPC;
break;
case CS7:
data |= SEVEN_BPC;
break;
default:
data |= EIGHT_BPC;
break;
}
/* stop bits */ //设置停止位
if (c_cflag & CSTOPB) {
data |= STOP_BIT_TWO;
} else {
/* otherwise 1 stop bit */
data |= STOP_BIT_ONE;
}
data |= UARTDM_MR2_ERROR_MODE_BMSK;
/* write parity/bits per char/stop bit configuration */
msm_hs_write(uport, UARTDM_MR2_ADDR, data);
/* Configure HW flow control */ //设置是否使用硬件流控
data = msm_hs_read(uport, UARTDM_MR1_ADDR);
data &= ~(UARTDM_MR1_CTS_CTL_BMSK |
UARTDM_MR1_RX_RDY_CTL_BMSK);
if (c_cflag & CRTSCTS) {
data |= UARTDM_MR1_CTS_CTL_BMSK;
data |= UARTDM_MR1_RX_RDY_CTL_BMSK;
}
msm_hs_write(uport, UARTDM_MR1_ADDR, data);
uport->ignore_status_mask = termios->c_iflag & INPCK;
uport->ignore_status_mask |= termios->c_iflag & IGNPAR;
uport->ignore_status_mask |= termios->c_iflag & IGNBRK;
uport->read_status_mask = (termios->c_cflag & CREAD);
msm_hs_write(uport, UARTDM_IMR_ADDR, 0);
/* Set Transmit software time out */
uart_update_timeout(uport, c_cflag, bps);
msm_hs_write(uport, UARTDM_CR_ADDR, RESET_RX);
msm_hs_write(uport, UARTDM_CR_ADDR, RESET_TX);
if (msm_uport->rx.flush == FLUSH_NONE) {
wake_lock(&msm_uport->rx.wake_lock);
msm_uport->rx.flush = FLUSH_IGNORE;
/*
* Before using dmov APIs make sure that
* previous writel are completed. Hence
* dsb requires here.
*/
mb();
msm_uport->rx_discard_flush_issued = true;
/* do discard flush */
msm_dmov_flush(msm_uport->dma_rx_channel, 0);
spin_unlock_irqrestore(&uport->lock, flags);
pr_debug("%s(): wainting for flush completion.\n",
__func__);
ret = wait_event_timeout(msm_uport->rx.wait,
msm_uport->rx_discard_flush_issued == false,
RX_FLUSH_COMPLETE_TIMEOUT);
if (!ret)
pr_err("%s(): Discard flush completion pending.\n",
__func__);
spin_lock_irqsave(&uport->lock, flags);
}
msm_hs_write(uport, UARTDM_IMR_ADDR, msm_uport->imr_reg);
mb();
spin_unlock_irqrestore(&uport->lock, flags);
mutex_unlock(&msm_uport->clk_mutex);
}

3：串口通讯问题总结：

遇见过模块不能响应AP的问题：

1：硬件流控问题，若模块使用了硬件流控，配置rfr与cts，使得模块认为

AP准备好了，可以发送数据了。

2：AP端波特率没有与模块匹配上，要是怀疑AP波特率设置是否ok，可以将串口线连接TX，

设置termios 波特率来看输出是否ok，这种方法还可以测试验证AP端各个波特率是否OK，我使用的

minicon可以验证到460800。