diff options
| author | Fabio Estevam <fabio.estevam@freescale.com> | 2015-01-08 19:17:05 -0200 |
|---|---|---|
| committer | Jason Liu <r64343@freescale.com> | 2015-02-02 14:47:20 +0800 |
| commit | 245bf82e27c46db4f25e58634860f407b4c05309 (patch) | |
| tree | e2eae93340278cd09e6ad98380a45632631f7181 | |
| parent | 96391f1b6535f8856149ebd8632c72e4561efdcf (diff) | |
MLK-10080 serial: imx: Fix imx_flush_buffer()
When running an userspace program that does a 'tcflush(fd, TCIOFLUSH)' call
we still see the last received character in the URXD register afterwards.
Clear UCR2_SRST bit so that the FIFO is flushed properly.
Since UCR2_SRST also resets some UART registers, we need to save and restore
some of them.
Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
(cherry picked from commit 87a72b6a6367a714026d5f38207301e7f53b0aca)
| -rw-r--r-- | drivers/tty/serial/imx.c | 26 |
1 files changed, 26 insertions, 0 deletions
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index 94aba1dae198..42128dc69573 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1383,12 +1383,38 @@ static void imx_shutdown(struct uart_port *port) static void imx_flush_buffer(struct uart_port *port) { + int i, temp; struct imx_port *sport = (struct imx_port *)port; if (sport->dma_is_enabled) { sport->tx_bytes = 0; dmaengine_terminate_all(sport->dma_chan_tx); } + + /* + * UCR2_SRST will reset the transmit and receive state machines, + * all FIFOs and register UBIR, UBMR, UBRC, + * and UTS[6-3], so save the required registers + */ + sport->saved_reg[0] = readl(sport->port.membase + UBIR); + sport->saved_reg[1] = readl(sport->port.membase + UBMR); + sport->saved_reg[2] = readl(sport->port.membase + UBRC); + sport->saved_reg[3] = readl(sport->port.membase + IMX21_UTS); + + i = 100; + + temp = readl(sport->port.membase + UCR2); + temp &= ~UCR2_SRST; + writel(temp, sport->port.membase + UCR2); + + while (!(readl(sport->port.membase + UCR2) & UCR2_SRST) && (--i > 0)) + udelay(1); + + /* Restore the registers */ + writel(sport->saved_reg[0], sport->port.membase + UBIR); + writel(sport->saved_reg[1], sport->port.membase + UBMR); + writel(sport->saved_reg[2], sport->port.membase + UBRC); + writel(sport->saved_reg[3], sport->port.membase + IMX21_UTS); } static void |