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serial: imx: clean up imx_poll_put_char()

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imx_put_poll_char() has been simplified to remove the code to disable
interrupts. The present code can corrupt register state when re-entered
from FIQ handler.

Switch to _relaxed() MMIO functions (which are safe for polled I/O and
needed to avoid taking spin locks).

Signed-off-by: Daniel Thompson <daniel.thompson@linaro.org>
Signed-off-by: Dirk Behme <dirk.behme@de.bosch.com>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: Huang Shijie <b32955@freescale.com>
Cc: linux-serial@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Daniel Thompson 2014-10-28 09:28:07 +01:00 committed by Greg Kroah-Hartman
parent 97f7547103
commit f968ef3494
1 changed files with 5 additions and 19 deletions
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24
drivers/tty/serial/imx.c
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@ -1457,42 +1457,28 @@ imx_verify_port(struct uart_port *port, struct serial_struct *ser)
#if defined(CONFIG_CONSOLE_POLL)
static int imx_poll_get_char(struct uart_port *port)
{
if (!(readl(port->membase + USR2) & USR2_RDR))
if (!(readl_relaxed(port->membase + USR2) & USR2_RDR))
return NO_POLL_CHAR;
return readl(port->membase + URXD0) & URXD_RX_DATA;
return readl_relaxed(port->membase + URXD0) & URXD_RX_DATA;
}
static void imx_poll_put_char(struct uart_port *port, unsigned char c)
{
struct imx_port_ucrs old_ucr;
unsigned int status;
/* save control registers */
imx_port_ucrs_save(port, &old_ucr);
/* disable interrupts */
writel(UCR1_UARTEN, port->membase + UCR1);
writel(old_ucr.ucr2 & ~(UCR2_ATEN | UCR2_RTSEN | UCR2_ESCI),
port->membase + UCR2);
writel(old_ucr.ucr3 & ~(UCR3_DCD | UCR3_RI | UCR3_DTREN),
port->membase + UCR3);
/* drain */
do {
status = readl(port->membase + USR1);
status = readl_relaxed(port->membase + USR1);
} while (~status & USR1_TRDY);
/* write */
writel(c, port->membase + URTX0);
writel_relaxed(c, port->membase + URTX0);
/* flush */
do {
status = readl(port->membase + USR2);
status = readl_relaxed(port->membase + USR2);
} while (~status & USR2_TXDC);
/* restore control registers */
imx_port_ucrs_restore(port, &old_ucr);
}
#endif