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serial: imx: Support sw flow control in DMA mode
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>
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@ -464,9 +464,11 @@ static void imx_enable_ms(struct uart_port *port)
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mod_timer(&sport->timer, jiffies);
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}
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static void imx_dma_tx(struct imx_port *sport);
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static inline void imx_transmit_buffer(struct imx_port *sport)
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{
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struct circ_buf *xmit = &sport->port.state->xmit;
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unsigned long temp;
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if (sport->port.x_char) {
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/* Send next char */
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@ -481,6 +483,22 @@ static inline void imx_transmit_buffer(struct imx_port *sport)
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return;
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}
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if (sport->dma_is_enabled) {
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/*
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* We've just sent a X-char Ensure the TX DMA is enabled
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* and the TX IRQ is disabled.
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**/
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temp = readl(sport->port.membase + UCR1);
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temp &= ~UCR1_TXMPTYEN;
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if (sport->dma_is_txing) {
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temp |= UCR1_TDMAEN;
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writel(temp, sport->port.membase + UCR1);
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} else {
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writel(temp, sport->port.membase + UCR1);
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imx_dma_tx(sport);
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}
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}
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while (!uart_circ_empty(xmit) &&
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!(readl(sport->port.membase + uts_reg(sport)) & UTS_TXFULL)) {
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/* send xmit->buf[xmit->tail]
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@ -497,7 +515,6 @@ static inline void imx_transmit_buffer(struct imx_port *sport)
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imx_stop_tx(&sport->port);
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}
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static void imx_dma_tx(struct imx_port *sport);
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static void dma_tx_callback(void *data)
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{
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struct imx_port *sport = data;
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@ -630,7 +647,16 @@ static void imx_start_tx(struct uart_port *port)
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}
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if (sport->dma_is_enabled) {
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/* FIXME: port->x_char must be transmitted if != 0 */
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if (sport->port.x_char) {
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/* We have X-char to send, so enable TX IRQ and
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* disable TX DMA to let TX interrupt to send X-char */
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temp = readl(sport->port.membase + UCR1);
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temp &= ~UCR1_TDMAEN;
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temp |= UCR1_TXMPTYEN;
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writel(temp, sport->port.membase + UCR1);
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return;
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}
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if (!uart_circ_empty(&port->state->xmit) &&
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!uart_tx_stopped(port))
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imx_dma_tx(sport);
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