serial: imx: clean up imx_poll_put_char()

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>

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index d2e6cf5a1ab836ffd9aff0e31f1fc080ad3e6a26..8d61aa98b932cf82925fcf98cc8587552d240346 100644 (file)
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -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