On Sun, Dec 18, 2011 at 06:34:15PM +0100, Dirk Behme wrote:
> From: Saleem Abdulrasool <compnerd@xxxxxxxxxxxx>
>
> 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 <compnerd@xxxxxxxxxxxx>
> Signed-off-by: Dirk Behme <dirk.behme@xxxxxxxxx>
> CC: Sascha Hauer <s.hauer@xxxxxxxxxxxxxx>
> CC: Fabio Estevam <festevam@xxxxxxxxx>
> CC: Uwe Kleine-König <u.kleine-koenig@xxxxxxxxxxxxxx>
> CC: linux-serial@xxxxxxxxxxxxxxx
> ---
> Note: Changes in the v2 compared to Saleem's original version:
> * Remove volatile form status variable
> * Remove blank line
> * Factor out imx_console_mode/restore()
>
> drivers/tty/serial/imx.c | 66 ++++++++++++++++++++++++++++++++++++++++++++++
> 1 files changed, 66 insertions(+), 0 deletions(-)
>
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index 6a01c2a..cd81ac0 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -102,6 +102,7 @@
> #define UCR2_STPB (1<<6) /* Stop */
> #define UCR2_WS (1<<5) /* Word size */
> #define UCR2_RTSEN (1<<4) /* Request to send interrupt enable */
> +#define UCR2_ATEN (1<<3) /* Aging Timer Enable */
> #define UCR2_TXEN (1<<2) /* Transmitter enabled */
> #define UCR2_RXEN (1<<1) /* Receiver enabled */
> #define UCR2_SRST (1<<0) /* SW reset */
> @@ -1104,6 +1105,66 @@ 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)
> +{
> + unsigned int status, cr1, cr2, cr3;
> + unsigned char c;
> +
> + /* save control registers */
> + imx_console_mode(port, &cr1, &cr2, &cr3);
> +
> + /* disable interrupts */
> + writel(UCR1_UARTEN, port->membase + UCR1);
> + writel(cr2 & ~(UCR2_ATEN | UCR2_RTSEN | UCR2_ESCI),
> + port->membase + UCR2);
> + writel(cr3 & ~(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_console_restore(port, cr1, cr2, cr3);
> +
> + return c & 0xff;
The 'c' is defined an 'unsigned char'. Do we still need '& 0xff'?
> +}
> +
> +static void imx_poll_put_char(struct uart_port *port, unsigned char c)
> +{
> + unsigned int status, cr1, cr2, cr3;
> +
> + /* save control registers */
> + imx_console_mode(port, &cr1, &cr2, &cr3);
> +
> + /* disable interrupts */
> + writel(UCR1_UARTEN, port->membase + UCR1);
> + writel(cr2 & ~(UCR2_ATEN | UCR2_RTSEN | UCR2_ESCI),
> + port->membase + UCR2);
> + writel(cr3 & ~(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_console_restore(port, cr1, cr2, cr3);
> +}
> +#endif
> +
> static struct uart_ops imx_pops = {
> .tx_empty = imx_tx_empty,
> .set_mctrl = imx_set_mctrl,
> @@ -1121,6 +1182,11 @@ static struct uart_ops imx_pops = {
> .request_port = imx_request_port,
> .config_port = imx_config_port,
> .verify_port = imx_verify_port,
> +
Unnecessary blank line?
Regards,
Shawn
> +#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];
> --
> 1.7.7.4
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