关于OK335D LINUX下485驱动的问题
OK335D LINUX下485使用的是UART2和GPIO3_2配合使用实现485驱动（见原理图），按我的理解就是把串口驱动实现为458驱动无非就是在串口发送时拉高或拉低GPIO3_2引脚，发送结束时做相反操作，按时这个485驱动在启动时会初始化这个GPIO3_2脚，我在驱动源码中serial_omap_startup（）、serial_omap_start_tx（）和serial_omap_stop_tx这几个函数中没找到初始化或控制GPIO3_2引脚的语句，或许是我看得不够仔细，飞凌工程师可以帮我指出来吗？如果不是按我理解的这样去做，请问是如何实现这个485驱动的？附上这几个函数的源码，谢谢static void serial_omap_start_tx(struct uart_port *port)
{
struct uart_omap_port *up = (struct uart_omap_port *)port;
struct circ_buf *xmit;
unsigned int start;
int ret = 0;
if (!up->use_dma) {
pm_runtime_get_sync(&up->pdev->dev);
serial_omap_enable_ier_thri(up);
pm_runtime_mark_last_busy(&up->pdev->dev);
pm_runtime_put_autosuspend(&up->pdev->dev);
return;
}
if (up->uart_dma.tx_dma_used)
return;
xmit = &up->port.state->xmit;
if (up->uart_dma.tx_dma_channel == OMAP_UART_DMA_CH_FREE) {
pm_runtime_get_sync(&up->pdev->dev);
ret = omap_request_dma(up->uart_dma.uart_dma_tx,
"UART Tx DMA",
(void *)uart_tx_dma_callback, up,
&(up->uart_dma.tx_dma_channel));
if (ret < 0) {
serial_omap_enable_ier_thri(up);
return;
}
}
spin_lock(&(up->uart_dma.tx_lock));
up->uart_dma.tx_dma_used = true;
spin_unlock(&(up->uart_dma.tx_lock));
start = up->uart_dma.tx_buf_dma_phys +
(xmit->tail & (UART_XMIT_SIZE - 1));
up->uart_dma.tx_buf_size = uart_circ_chars_pending(xmit);
/*
* It is a circular buffer. See if the buffer has wounded back.
* If yes it will have to be transferred in two separate dma
* transfers
*/
if (start + up->uart_dma.tx_buf_size >=
up->uart_dma.tx_buf_dma_phys + UART_XMIT_SIZE)
up->uart_dma.tx_buf_size =
(up->uart_dma.tx_buf_dma_phys +
UART_XMIT_SIZE) - start;
omap_set_dma_dest_params(up->uart_dma.tx_dma_channel, 0,
OMAP_DMA_AMODE_CONSTANT,
up->uart_dma.uart_base, 0, 0);
omap_set_dma_src_params(up->uart_dma.tx_dma_channel, 0,
OMAP_DMA_AMODE_POST_INC, start, 0, 0);
omap_set_dma_transfer_params(up->uart_dma.tx_dma_channel,
OMAP_DMA_DATA_TYPE_S8,
up->uart_dma.tx_buf_size, 1,
OMAP_DMA_SYNC_ELEMENT,
up->uart_dma.uart_dma_tx, 0);
/* FIXME: Cache maintenance needed here? */
omap_start_dma(up->uart_dma.tx_dma_channel);
}
static void serial_omap_stop_tx(struct uart_port *port)
{
struct uart_omap_port *up = (struct uart_omap_port *)port;
if (up->use_dma &&
up->uart_dma.tx_dma_channel != OMAP_UART_DMA_CH_FREE) {
/*
* Check if dma is still active. If yes do nothing,
* return. Else stop dma
*/
if (omap_get_dma_active_status(up->uart_dma.tx_dma_channel))
return;
omap_stop_dma(up->uart_dma.tx_dma_channel);
omap_free_dma(up->uart_dma.tx_dma_channel);
up->uart_dma.tx_dma_channel = OMAP_UART_DMA_CH_FREE;
pm_runtime_mark_last_busy(&up->pdev->dev);
pm_runtime_put_autosuspend(&up->pdev->dev);
}
pm_runtime_get_sync(&up->pdev->dev);
if (up->ier & UART_IER_THRI) {
up->ier &= ~UART_IER_THRI;
serial_out(up, UART_IER, up->ier);
}
pm_runtime_mark_last_busy(&up->pdev->dev);
pm_runtime_put_autosuspend(&up->pdev->dev);
}
static int serial_omap_startup(struct uart_port *port)
{
struct uart_omap_port *up = (struct uart_omap_port *)port;
unsigned long flags = 0;
int retval;
/*
* Allocate the IRQ
*/
retval = request_irq(up->port.irq, serial_omap_irq, up->port.irqflags,
up->name, up);
if (retval)
return retval;
dev_dbg(up->port.dev, "serial_omap_startup+%d\n", up->port.line);
pm_runtime_get_sync(&up->pdev->dev);
/*
* Clear the FIFO buffers and disable them.
* (they will be reenabled in set_termios())
*/
serial_omap_clear_fifos(up);
/* For Hardware flow control */
serial_out(up, UART_MCR, UART_MCR_RTS);
/*
* Clear the interrupt registers.
*/
(void) serial_in(up, UART_LSR);
if (serial_in(up, UART_LSR) & UART_LSR_DR)
(void) serial_in(up, UART_RX);
(void) serial_in(up, UART_IIR);
(void) serial_in(up, UART_MSR);
/*
* Now, initialize the UART
*/
serial_out(up, UART_LCR, UART_LCR_WLEN8);
spin_lock_irqsave(&up->port.lock, flags);
/*
* Most PC uarts need OUT2 raised to enable interrupts.
*/
up->port.mctrl |= TIOCM_OUT2;
serial_omap_set_mctrl(&up->port, up->port.mctrl);
spin_unlock_irqrestore(&up->port.lock, flags);
up->msr_saved_flags = 0;
if (up->use_dma) {
free_page((unsigned long)up->port.state->xmit.buf);
up->port.state->xmit.buf = dma_alloc_coherent(NULL,
UART_XMIT_SIZE,
(dma_addr_t *)&(up->uart_dma.tx_buf_dma_phys),
0);
init_timer(&(up->uart_dma.rx_timer));
up->uart_dma.rx_timer.function = serial_omap_rxdma_poll;
up->uart_dma.rx_timer.data = up->port.line;
/* Currently the buffer size is 4KB. Can increase it */
up->uart_dma.rx_buf = dma_alloc_coherent(NULL,
up->uart_dma.rx_buf_size,
(dma_addr_t *)&(up->uart_dma.rx_buf_dma_phys), 0);
}
/*
* Finally, enable interrupts. Note: Modem status interrupts
* are set via set_termios(), which will be occurring imminently
* anyway, so we don't enable them here.
*/
up->ier = UART_IER_RLSI | UART_IER_RDI;
serial_out(up, UART_IER, up->ier);
/* Enable module level wake up */
serial_out(up, UART_OMAP_WER, OMAP_UART_WER_MOD_WKUP);
pm_runtime_mark_last_busy(&up->pdev->dev);
pm_runtime_put_autosuspend(&up->pdev->dev);
up->port_activity = jiffies;
return 0;
}
RS485 驱动 源码路径 ： drivers/tty/serial/omap-serial.c 飞凌-unix 发表于 2013-10-24 16:56 static/image/common/back.gif
RS485 驱动 源码路径 ： drivers/tty/serial/omap-serial.c
上的几个函数就是从这个源码路径复制的！ 楼主如果你想写的是驱动程序，单单复制代码是不行的，其他的东西也要改啊，你有没有屏蔽之前的驱动啊？ 楼上朋友，正解，RS485的驱动是有“串口驱动+GPIO控制”实现的，GPIO控制部分体现在用户程序，楼主可以看一下我们的RS485测试APP，近期将发布最新测试程序，里面会含有RS485测试源码，有GPIO控制部分，如果着急需要可以联系技术服务部门，或者加我的工作QQ：2652547374. RS485的测试位于光盘目录：OK335xD光盘资料（A）\linux\src\test.tar.bz2 测试程序压缩包中。
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