Commit 91a1a909 authored by Jiada Wang's avatar Jiada Wang Committed by Greg Kroah-Hartman
Browse files

serial: imx: Support sw flow control in DMA mode 



This patch adds Software flow control support in DMA mode.

Signed-off-by: default avatarJiada Wang <jiada_wang@mentor.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7e2fb5aa

drivers/tty/serial/imx.c

+28 −2
Original line number Diff line number Diff line
@@ -464,9 +464,11 @@ static void imx_enable_ms(struct uart_port *port) 
	mod_timer(&sport->timer, jiffies);

}



static void imx_dma_tx(struct imx_port *sport);

static inline void imx_transmit_buffer(struct imx_port *sport)

{

	struct circ_buf *xmit = &sport->port.state->xmit;

	unsigned long temp;



	if (sport->port.x_char) {

		/* Send next char */
@@ -481,6 +483,22 @@ static inline void imx_transmit_buffer(struct imx_port *sport) 
		return;

	}



	if (sport->dma_is_enabled) {

		/*

		 * We've just sent a X-char Ensure the TX DMA is enabled

		 * and the TX IRQ is disabled.

		 **/

		temp = readl(sport->port.membase + UCR1);

		temp &= ~UCR1_TXMPTYEN;

		if (sport->dma_is_txing) {

			temp |= UCR1_TDMAEN;

			writel(temp, sport->port.membase + UCR1);

		} else {

			writel(temp, sport->port.membase + UCR1);

			imx_dma_tx(sport);

		}

	}



	while (!uart_circ_empty(xmit) &&

	       !(readl(sport->port.membase + uts_reg(sport)) & UTS_TXFULL)) {

		/* send xmit->buf[xmit->tail]
@@ -497,7 +515,6 @@ static inline void imx_transmit_buffer(struct imx_port *sport) 
		imx_stop_tx(&sport->port);

}



static void imx_dma_tx(struct imx_port *sport);

static void dma_tx_callback(void *data)

{

	struct imx_port *sport = data;
@@ -630,7 +647,16 @@ static void imx_start_tx(struct uart_port *port) 
	}



	if (sport->dma_is_enabled) {

		/* FIXME: port->x_char must be transmitted if != 0 */

		if (sport->port.x_char) {

			/* We have X-char to send, so enable TX IRQ and

			 * disable TX DMA to let TX interrupt to send X-char */

			temp = readl(sport->port.membase + UCR1);

			temp &= ~UCR1_TDMAEN;

			temp |= UCR1_TXMPTYEN;

			writel(temp, sport->port.membase + UCR1);

			return;

		}



		if (!uart_circ_empty(&port->state->xmit) &&

		    !uart_tx_stopped(port))

			imx_dma_tx(sport);