From bbc70e2695e527cb599d6b78ef187b8578c43948 Mon Sep 17 00:00:00 2001 From: Saleem Abdulrasool Date: Thu, 22 Dec 2011 09:57:53 +0100 Subject: [PATCH] imx: add polled io uart methods These methods are invoked if the iMX uart is used in conjuction with kgdb during early boot. In order to access the UART without the interrupts, the kernel uses the basic polling methods for IO with the device. With these methods implemented, it is now possible to enable kgdb during early boot over serial. Signed-off-by: Saleem Abdulrasool Signed-off-by: Dirk Behme CC: Sascha Hauer CC: Fabio Estevam CC: Uwe Kleine-Koenig CC: linux-serial@vger.kernel.org CC: Alan Cox Signed-off-by: Shawn Guo Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/imx.c | 68 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 68 insertions(+) diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c index d7acd41497d2..44564e3fcdbe 100644 --- a/drivers/tty/serial/imx.c +++ b/drivers/tty/serial/imx.c @@ -1428,6 +1428,70 @@ imx_verify_port(struct uart_port *port, struct serial_struct *ser) return ret; } +#if defined(CONFIG_CONSOLE_POLL) +static int imx_poll_get_char(struct uart_port *port) +{ + struct imx_port_ucrs old_ucr; + unsigned int status; + unsigned char c; + + /* 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); + + /* poll */ + do { + status = readl(port->membase + USR2); + } while (~status & USR2_RDR); + + /* read */ + c = readl(port->membase + URXD0); + + /* restore control registers */ + imx_port_ucrs_restore(port, &old_ucr); + + return c; +} + +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); + } while (~status & USR1_TRDY); + + /* write */ + writel(c, port->membase + URTX0); + + /* flush */ + do { + status = readl(port->membase + USR2); + } while (~status & USR2_TXDC); + + /* restore control registers */ + imx_port_ucrs_restore(port, &old_ucr); +} +#endif + static struct uart_ops imx_pops = { .tx_empty = imx_tx_empty, .set_mctrl = imx_set_mctrl, @@ -1445,6 +1509,10 @@ static struct uart_ops imx_pops = { .request_port = imx_request_port, .config_port = imx_config_port, .verify_port = imx_verify_port, +#if defined(CONFIG_CONSOLE_POLL) + .poll_get_char = imx_poll_get_char, + .poll_put_char = imx_poll_put_char, +#endif }; static struct imx_port *imx_ports[UART_NR]; -- 2.39.5