read this:
and this:
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:
c. next all these information will feed into serial_core.c (USB is not included here):
And here u can see how u can disable the signal from software standpoint, eg,
In particular:
78 static void uart_stop(struct tty_struct *tty)
79 {
80 struct uart_state *state = tty->driver_data;
81 struct uart_port *port = state->uart_port;
82 unsigned long flags;
83
84 spin_lock_irqsave(&port->lock, flags);
85 port->ops->stop_tx(port);
86 spin_unlock_irqrestore(&port->lock, flags);
87 }
88
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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Regards,
Peter Teoh