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serial: imx: Support sw flow control in DMA mode

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This patch adds Software flow control support in DMA mode.

Signed-off-by: Jiada Wang <jiada_wang@mentor.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiada Wang 2014-12-09 18:11:36 +09:00 committed by Greg Kroah-Hartman
parent 7e2fb5aa8d
commit 91a1a909f9
1 changed files with 28 additions and 2 deletions
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30
drivers/tty/serial/imx.c
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@ -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);