read this: http://elinux.org/Disable_Console and this: http://elinux.org/Kernel_Debugging_Tips#Controlling_console_output Perhaps u can extract relevant APIs from below URLs to solve your problem: a. at the hardware level, serial communication can come from UART interface, or infrared interface, or USB. b. next, is the 8250.c handler: http://lxr.free-electrons.com/source/drivers/tty/serial/<http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c>8250_*.c (star represent the different hardware devices handling the serial signals). c. next all these information will feed into serial_core.c (USB is not included here): http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c And here u can see how u can disable the signal from software standpoint, eg, In particular: 78 <http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c#L78> static void uart_stop <http://lxr.free-electrons.com/ident?i=uart_stop>(struct tty_struct <http://lxr.free-electrons.com/ident?i=tty_struct> *tty <http://lxr.free-electrons.com/ident?i=tty>) 79 <http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c#L79> { 80 <http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c#L80> struct uart_state <http://lxr.free-electrons.com/ident?i=uart_state> *state <http://lxr.free-electrons.com/ident?i=state> = tty <http://lxr.free-electrons.com/ident?i=tty>->driver_data <http://lxr.free-electrons.com/ident?i=driver_data>; 81 <http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c#L81> struct uart_port <http://lxr.free-electrons.com/ident?i=uart_port> *port <http://lxr.free-electrons.com/ident?i=port> = state <http://lxr.free-electrons.com/ident?i=state>->uart_port <http://lxr.free-electrons.com/ident?i=uart_port>; 82 <http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c#L82> unsigned long flags <http://lxr.free-electrons.com/ident?i=flags>; 83 <http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c#L83> 84 <http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c#L84> spin_lock_irqsave <http://lxr.free-electrons.com/ident?i=spin_lock_irqsave>(&port <http://lxr.free-electrons.com/ident?i=port>->lock <http://lxr.free-electrons.com/ident?i=lock>, flags <http://lxr.free-electrons.com/ident?i=flags>); 85 <http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c#L85> port <http://lxr.free-electrons.com/ident?i=port>->ops <http://lxr.free-electrons.com/ident?i=ops>->stop_tx(port <http://lxr.free-electrons.com/ident?i=port>); 86 <http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c#L86> spin_unlock_irqrestore <http://lxr.free-electrons.com/ident?i=spin_unlock_irqrestore>(&port <http://lxr.free-electrons.com/ident?i=port>->lock <http://lxr.free-electrons.com/ident?i=lock>, flags <http://lxr.free-electrons.com/ident?i=flags>); 87 <http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c#L87> } 88 <http://lxr.free-electrons.com/source/drivers/tty/serial/serial_core.c#L88>
From above, u can see stop_tx() can be called, looking further into 8250.c:
static void serial8250_stop_tx(struct uart_port *port) { struct uart_8250_port *up = container_of(port, struct uart_8250_port, port); __stop_tx(up); /* * We really want to stop the transmitter from sending. */ if (up->port.type == PORT_16C950) { up->acr |= UART_ACR_TXDIS; serial_icr_write(up, UART_ACR, up->acr); } } And referring further to definition: /* * The 16C950 Additional Control Register */ #define UART_ACR_RXDIS 0x01 /* Receiver disable */ #define UART_ACR_TXDIS 0x02 /* Transmitter disable */ So perhaps writing UART_ACR_XXX_DIS will disable the input/output: drivers/tty/serial/8250.c: up->acr |= UART_ACR_TXDIS; drivers/tty/serial/8250.c: up->acr &= ~UART_ACR_TXDIS; Experiment first....I am just guessing.... On Wed, Jan 4, 2012 at 8:43 AM, hz hanks <hankshz@gmail.com> wrote:
Hi, all~ I'm studying in an embedded Linux board with only one uart, which is set default as the console display. Now as I try to develop uart driver, I want to shutdown this console redirection temporarily. But I don't know how? I search the Internet, but there's only the tutorial for setting this redirection rather than shutdown it. Is there anyone can help? Thank you very much.
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