From 91a1a909f9217abb16c5bb3ec2ae606a9fc085e8 Mon Sep 17 00:00:00 2001 From: Jiada Wang Date: Tue, 9 Dec 2014 18:11:36 +0900 Subject: [PATCH] serial: imx: Support sw flow control in DMA mode This patch adds Software flow control support in DMA mode. Signed-off-by: Jiada Wang Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/imx.c | 30 ++++++++++++++++++++++++++++-- 1 file changed, 28 insertions(+), 2 deletions(-) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 5a7da01..72b800b 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -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); -- 2.7.4