in serial/serial_core.c [788:990]
static int uart_set_info(struct tty_struct *tty, struct tty_port *port,
struct uart_state *state,
struct serial_struct *new_info)
{
struct uart_port *uport = uart_port_check(state);
unsigned long new_port;
unsigned int change_irq, change_port, closing_wait;
unsigned int old_custom_divisor, close_delay;
upf_t old_flags, new_flags;
int retval = 0;
if (!uport)
return -EIO;
new_port = new_info->port;
if (HIGH_BITS_OFFSET)
new_port += (unsigned long) new_info->port_high << HIGH_BITS_OFFSET;
new_info->irq = irq_canonicalize(new_info->irq);
close_delay = msecs_to_jiffies(new_info->close_delay * 10);
closing_wait = new_info->closing_wait == ASYNC_CLOSING_WAIT_NONE ?
ASYNC_CLOSING_WAIT_NONE :
msecs_to_jiffies(new_info->closing_wait * 10);
change_irq = !(uport->flags & UPF_FIXED_PORT)
&& new_info->irq != uport->irq;
/*
* Since changing the 'type' of the port changes its resource
* allocations, we should treat type changes the same as
* IO port changes.
*/
change_port = !(uport->flags & UPF_FIXED_PORT)
&& (new_port != uport->iobase ||
(unsigned long)new_info->iomem_base != uport->mapbase ||
new_info->hub6 != uport->hub6 ||
new_info->io_type != uport->iotype ||
new_info->iomem_reg_shift != uport->regshift ||
new_info->type != uport->type);
old_flags = uport->flags;
new_flags = (__force upf_t)new_info->flags;
old_custom_divisor = uport->custom_divisor;
if (!capable(CAP_SYS_ADMIN)) {
retval = -EPERM;
if (change_irq || change_port ||
(new_info->baud_base != uport->uartclk / 16) ||
(close_delay != port->close_delay) ||
(closing_wait != port->closing_wait) ||
(new_info->xmit_fifo_size &&
new_info->xmit_fifo_size != uport->fifosize) ||
(((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
goto exit;
uport->flags = ((uport->flags & ~UPF_USR_MASK) |
(new_flags & UPF_USR_MASK));
uport->custom_divisor = new_info->custom_divisor;
goto check_and_exit;
}
if (change_irq || change_port) {
retval = security_locked_down(LOCKDOWN_TIOCSSERIAL);
if (retval)
goto exit;
}
/*
* Ask the low level driver to verify the settings.
*/
if (uport->ops->verify_port)
retval = uport->ops->verify_port(uport, new_info);
if ((new_info->irq >= nr_irqs) || (new_info->irq < 0) ||
(new_info->baud_base < 9600))
retval = -EINVAL;
if (retval)
goto exit;
if (change_port || change_irq) {
retval = -EBUSY;
/*
* Make sure that we are the sole user of this port.
*/
if (tty_port_users(port) > 1)
goto exit;
/*
* We need to shutdown the serial port at the old
* port/type/irq combination.
*/
uart_shutdown(tty, state);
}
if (change_port) {
unsigned long old_iobase, old_mapbase;
unsigned int old_type, old_iotype, old_hub6, old_shift;
old_iobase = uport->iobase;
old_mapbase = uport->mapbase;
old_type = uport->type;
old_hub6 = uport->hub6;
old_iotype = uport->iotype;
old_shift = uport->regshift;
/*
* Free and release old regions
*/
if (old_type != PORT_UNKNOWN && uport->ops->release_port)
uport->ops->release_port(uport);
uport->iobase = new_port;
uport->type = new_info->type;
uport->hub6 = new_info->hub6;
uport->iotype = new_info->io_type;
uport->regshift = new_info->iomem_reg_shift;
uport->mapbase = (unsigned long)new_info->iomem_base;
/*
* Claim and map the new regions
*/
if (uport->type != PORT_UNKNOWN && uport->ops->request_port) {
retval = uport->ops->request_port(uport);
} else {
/* Always success - Jean II */
retval = 0;
}
/*
* If we fail to request resources for the
* new port, try to restore the old settings.
*/
if (retval) {
uport->iobase = old_iobase;
uport->type = old_type;
uport->hub6 = old_hub6;
uport->iotype = old_iotype;
uport->regshift = old_shift;
uport->mapbase = old_mapbase;
if (old_type != PORT_UNKNOWN) {
retval = uport->ops->request_port(uport);
/*
* If we failed to restore the old settings,
* we fail like this.
*/
if (retval)
uport->type = PORT_UNKNOWN;
/*
* We failed anyway.
*/
retval = -EBUSY;
}
/* Added to return the correct error -Ram Gupta */
goto exit;
}
}
if (change_irq)
uport->irq = new_info->irq;
if (!(uport->flags & UPF_FIXED_PORT))
uport->uartclk = new_info->baud_base * 16;
uport->flags = (uport->flags & ~UPF_CHANGE_MASK) |
(new_flags & UPF_CHANGE_MASK);
uport->custom_divisor = new_info->custom_divisor;
port->close_delay = close_delay;
port->closing_wait = closing_wait;
if (new_info->xmit_fifo_size)
uport->fifosize = new_info->xmit_fifo_size;
check_and_exit:
retval = 0;
if (uport->type == PORT_UNKNOWN)
goto exit;
if (tty_port_initialized(port)) {
if (((old_flags ^ uport->flags) & UPF_SPD_MASK) ||
old_custom_divisor != uport->custom_divisor) {
/*
* If they're setting up a custom divisor or speed,
* instead of clearing it, then bitch about it.
*/
if (uport->flags & UPF_SPD_MASK) {
dev_notice_ratelimited(uport->dev,
"%s sets custom speed on %s. This is deprecated.\n",
current->comm,
tty_name(port->tty));
}
uart_change_speed(tty, state, NULL);
}
} else {
retval = uart_startup(tty, state, 1);
if (retval == 0)
tty_port_set_initialized(port, true);
if (retval > 0)
retval = 0;
}
exit:
return retval;
}