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serial_core.c
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/*
* linux/drivers/char/core.c
*
* Driver core for serial ports
*
* Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
*
* Copyright 1999 ARM Limited
* Copyright (C) 2000-2001 Deep Blue Solutions Ltd.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/console.h>
#include <linux/serial_core.h>
#include <linux/smp_lock.h>
#include <linux/device.h>
#include <linux/serial.h> /* for serial_state and serial_icounter_struct */
#include <linux/delay.h>
#include <linux/mutex.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#undef DEBUG
#ifdef DEBUG
#define DPRINTK(x...) printk(x)
#else
#define DPRINTK(x...) do { } while (0)
#endif
/*
* This is used to lock changes in serial line configuration.
*/
static DEFINE_MUTEX(port_mutex);
/*
* lockdep: port->lock is initialized in two places, but we
* want only one lock-class:
*/
static struct lock_class_key port_lock_key;
#define HIGH_BITS_OFFSET ((sizeof(long)-sizeof(int))*8)
#define uart_users(state) ((state)->count + ((state)->info ? (state)->info->blocked_open : 0))
#ifdef CONFIG_SERIAL_CORE_CONSOLE
#define uart_console(port) ((port)->cons && (port)->cons->index == (port)->line)
#else
#define uart_console(port) (0)
#endif
static void uart_change_speed(struct uart_state *state, struct termios *old_termios);
static void uart_wait_until_sent(struct tty_struct *tty, int timeout);
static void uart_change_pm(struct uart_state *state, int pm_state);
/*
* This routine is used by the interrupt handler to schedule processing in
* the software interrupt portion of the driver.
*/
void uart_write_wakeup(struct uart_port *port)
{
struct uart_info *info = port->info;
/*
* This means you called this function _after_ the port was
* closed. No cookie for you.
*/
BUG_ON(!info);
tasklet_schedule(&info->tlet);
}
static void uart_stop(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->port;
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
port->ops->stop_tx(port);
spin_unlock_irqrestore(&port->lock, flags);
}
static void __uart_start(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->port;
if (!uart_circ_empty(&state->info->xmit) && state->info->xmit.buf &&
!tty->stopped && !tty->hw_stopped)
port->ops->start_tx(port);
}
static void uart_start(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->port;
unsigned long flags;
spin_lock_irqsave(&port->lock, flags);
__uart_start(tty);
spin_unlock_irqrestore(&port->lock, flags);
}
static void uart_tasklet_action(unsigned long data)
{
struct uart_state *state = (struct uart_state *)data;
tty_wakeup(state->info->tty);
}
static inline void
uart_update_mctrl(struct uart_port *port, unsigned int set, unsigned int clear)
{
unsigned long flags;
unsigned int old;
spin_lock_irqsave(&port->lock, flags);
old = port->mctrl;
port->mctrl = (old & ~clear) | set;
if (old != port->mctrl)
port->ops->set_mctrl(port, port->mctrl);
spin_unlock_irqrestore(&port->lock, flags);
}
#define uart_set_mctrl(port,set) uart_update_mctrl(port,set,0)
#define uart_clear_mctrl(port,clear) uart_update_mctrl(port,0,clear)
/*
* Startup the port. This will be called once per open. All calls
* will be serialised by the per-port semaphore.
*/
static int uart_startup(struct uart_state *state, int init_hw)
{
struct uart_info *info = state->info;
struct uart_port *port = state->port;
unsigned long page;
int retval = 0;
if (info->flags & UIF_INITIALIZED)
return 0;
/*
* Set the TTY IO error marker - we will only clear this
* once we have successfully opened the port. Also set
* up the tty->alt_speed kludge
*/
set_bit(TTY_IO_ERROR, &info->tty->flags);
if (port->type == PORT_UNKNOWN)
return 0;
/*
* Initialise and allocate the transmit and temporary
* buffer.
*/
if (!info->xmit.buf) {
page = get_zeroed_page(GFP_KERNEL);
if (!page)
return -ENOMEM;
info->xmit.buf = (unsigned char *) page;
uart_circ_clear(&info->xmit);
}
retval = port->ops->startup(port);
if (retval == 0) {
if (init_hw) {
/*
* Initialise the hardware port settings.
*/
uart_change_speed(state, NULL);
/*
* Setup the RTS and DTR signals once the
* port is open and ready to respond.
*/
if (info->tty->termios->c_cflag & CBAUD)
uart_set_mctrl(port, TIOCM_RTS | TIOCM_DTR);
}
if (info->flags & UIF_CTS_FLOW) {
spin_lock_irq(&port->lock);
if (!(port->ops->get_mctrl(port) & TIOCM_CTS))
info->tty->hw_stopped = 1;
spin_unlock_irq(&port->lock);
}
info->flags |= UIF_INITIALIZED;
clear_bit(TTY_IO_ERROR, &info->tty->flags);
}
if (retval && capable(CAP_SYS_ADMIN))
retval = 0;
return retval;
}
/*
* This routine will shutdown a serial port; interrupts are disabled, and
* DTR is dropped if the hangup on close termio flag is on. Calls to
* uart_shutdown are serialised by the per-port semaphore.
*/
static void uart_shutdown(struct uart_state *state)
{
struct uart_info *info = state->info;
struct uart_port *port = state->port;
/*
* Set the TTY IO error marker
*/
if (info->tty)
set_bit(TTY_IO_ERROR, &info->tty->flags);
if (info->flags & UIF_INITIALIZED) {
info->flags &= ~UIF_INITIALIZED;
/*
* Turn off DTR and RTS early.
*/
if (!info->tty || (info->tty->termios->c_cflag & HUPCL))
uart_clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
/*
* clear delta_msr_wait queue to avoid mem leaks: we may free
* the irq here so the queue might never be woken up. Note
* that we won't end up waiting on delta_msr_wait again since
* any outstanding file descriptors should be pointing at
* hung_up_tty_fops now.
*/
wake_up_interruptible(&info->delta_msr_wait);
/*
* Free the IRQ and disable the port.
*/
port->ops->shutdown(port);
/*
* Ensure that the IRQ handler isn't running on another CPU.
*/
synchronize_irq(port->irq);
}
/*
* kill off our tasklet
*/
tasklet_kill(&info->tlet);
/*
* Free the transmit buffer page.
*/
if (info->xmit.buf) {
free_page((unsigned long)info->xmit.buf);
info->xmit.buf = NULL;
}
}
/**
* uart_update_timeout - update per-port FIFO timeout.
* @port: uart_port structure describing the port
* @cflag: termios cflag value
* @baud: speed of the port
*
* Set the port FIFO timeout value. The @cflag value should
* reflect the actual hardware settings.
*/
void
uart_update_timeout(struct uart_port *port, unsigned int cflag,
unsigned int baud)
{
unsigned int bits;
/* byte size and parity */
switch (cflag & CSIZE) {
case CS5:
bits = 7;
break;
case CS6:
bits = 8;
break;
case CS7:
bits = 9;
break;
default:
bits = 10;
break; // CS8
}
if (cflag & CSTOPB)
bits++;
if (cflag & PARENB)
bits++;
/*
* The total number of bits to be transmitted in the fifo.
*/
bits = bits * port->fifosize;
/*
* Figure the timeout to send the above number of bits.
* Add .02 seconds of slop
*/
port->timeout = (HZ * bits) / baud + HZ/50;
}
EXPORT_SYMBOL(uart_update_timeout);
/**
* uart_get_baud_rate - return baud rate for a particular port
* @port: uart_port structure describing the port in question.
* @termios: desired termios settings.
* @old: old termios (or NULL)
* @min: minimum acceptable baud rate
* @max: maximum acceptable baud rate
*
* Decode the termios structure into a numeric baud rate,
* taking account of the magic 38400 baud rate (with spd_*
* flags), and mapping the %B0 rate to 9600 baud.
*
* If the new baud rate is invalid, try the old termios setting.
* If it's still invalid, we try 9600 baud.
*
* Update the @termios structure to reflect the baud rate
* we're actually going to be using.
*/
unsigned int
uart_get_baud_rate(struct uart_port *port, struct termios *termios,
struct termios *old, unsigned int min, unsigned int max)
{
unsigned int try, baud, altbaud = 38400;
upf_t flags = port->flags & UPF_SPD_MASK;
if (flags == UPF_SPD_HI)
altbaud = 57600;
if (flags == UPF_SPD_VHI)
altbaud = 115200;
if (flags == UPF_SPD_SHI)
altbaud = 230400;
if (flags == UPF_SPD_WARP)
altbaud = 460800;
for (try = 0; try < 2; try++) {
baud = tty_termios_baud_rate(termios);
/*
* The spd_hi, spd_vhi, spd_shi, spd_warp kludge...
* Die! Die! Die!
*/
if (baud == 38400)
baud = altbaud;
/*
* Special case: B0 rate.
*/
if (baud == 0)
baud = 9600;
if (baud >= min && baud <= max)
return baud;
/*
* Oops, the quotient was zero. Try again with
* the old baud rate if possible.
*/
termios->c_cflag &= ~CBAUD;
if (old) {
termios->c_cflag |= old->c_cflag & CBAUD;
old = NULL;
continue;
}
/*
* As a last resort, if the quotient is zero,
* default to 9600 bps
*/
termios->c_cflag |= B9600;
}
return 0;
}
EXPORT_SYMBOL(uart_get_baud_rate);
/**
* uart_get_divisor - return uart clock divisor
* @port: uart_port structure describing the port.
* @baud: desired baud rate
*
* Calculate the uart clock divisor for the port.
*/
unsigned int
uart_get_divisor(struct uart_port *port, unsigned int baud)
{
unsigned int quot;
/*
* Old custom speed handling.
*/
if (baud == 38400 && (port->flags & UPF_SPD_MASK) == UPF_SPD_CUST)
quot = port->custom_divisor;
else
quot = (port->uartclk + (8 * baud)) / (16 * baud);
return quot;
}
EXPORT_SYMBOL(uart_get_divisor);
static void
uart_change_speed(struct uart_state *state, struct termios *old_termios)
{
struct tty_struct *tty = state->info->tty;
struct uart_port *port = state->port;
struct termios *termios;
/*
* If we have no tty, termios, or the port does not exist,
* then we can't set the parameters for this port.
*/
if (!tty || !tty->termios || port->type == PORT_UNKNOWN)
return;
termios = tty->termios;
/*
* Set flags based on termios cflag
*/
if (termios->c_cflag & CRTSCTS)
state->info->flags |= UIF_CTS_FLOW;
else
state->info->flags &= ~UIF_CTS_FLOW;
if (termios->c_cflag & CLOCAL)
state->info->flags &= ~UIF_CHECK_CD;
else
state->info->flags |= UIF_CHECK_CD;
port->ops->set_termios(port, termios, old_termios);
}
static inline void
__uart_put_char(struct uart_port *port, struct circ_buf *circ, unsigned char c)
{
unsigned long flags;
if (!circ->buf)
return;
spin_lock_irqsave(&port->lock, flags);
if (uart_circ_chars_free(circ) != 0) {
circ->buf[circ->head] = c;
circ->head = (circ->head + 1) & (UART_XMIT_SIZE - 1);
}
spin_unlock_irqrestore(&port->lock, flags);
}
static void uart_put_char(struct tty_struct *tty, unsigned char ch)
{
struct uart_state *state = tty->driver_data;
__uart_put_char(state->port, &state->info->xmit, ch);
}
static void uart_flush_chars(struct tty_struct *tty)
{
uart_start(tty);
}
static int
uart_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port;
struct circ_buf *circ;
unsigned long flags;
int c, ret = 0;
/*
* This means you called this function _after_ the port was
* closed. No cookie for you.
*/
if (!state || !state->info) {
WARN_ON(1);
return -EL3HLT;
}
port = state->port;
circ = &state->info->xmit;
if (!circ->buf)
return 0;
spin_lock_irqsave(&port->lock, flags);
while (1) {
c = CIRC_SPACE_TO_END(circ->head, circ->tail, UART_XMIT_SIZE);
if (count < c)
c = count;
if (c <= 0)
break;
memcpy(circ->buf + circ->head, buf, c);
circ->head = (circ->head + c) & (UART_XMIT_SIZE - 1);
buf += c;
count -= c;
ret += c;
}
spin_unlock_irqrestore(&port->lock, flags);
uart_start(tty);
return ret;
}
static int uart_write_room(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
return uart_circ_chars_free(&state->info->xmit);
}
static int uart_chars_in_buffer(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
return uart_circ_chars_pending(&state->info->xmit);
}
static void uart_flush_buffer(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->port;
unsigned long flags;
/*
* This means you called this function _after_ the port was
* closed. No cookie for you.
*/
if (!state || !state->info) {
WARN_ON(1);
return;
}
DPRINTK("uart_flush_buffer(%d) called\n", tty->index);
spin_lock_irqsave(&port->lock, flags);
uart_circ_clear(&state->info->xmit);
spin_unlock_irqrestore(&port->lock, flags);
tty_wakeup(tty);
}
/*
* This function is used to send a high-priority XON/XOFF character to
* the device
*/
static void uart_send_xchar(struct tty_struct *tty, char ch)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->port;
unsigned long flags;
if (port->ops->send_xchar)
port->ops->send_xchar(port, ch);
else {
port->x_char = ch;
if (ch) {
spin_lock_irqsave(&port->lock, flags);
port->ops->start_tx(port);
spin_unlock_irqrestore(&port->lock, flags);
}
}
}
static void uart_throttle(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
if (I_IXOFF(tty))
uart_send_xchar(tty, STOP_CHAR(tty));
if (tty->termios->c_cflag & CRTSCTS)
uart_clear_mctrl(state->port, TIOCM_RTS);
}
static void uart_unthrottle(struct tty_struct *tty)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->port;
if (I_IXOFF(tty)) {
if (port->x_char)
port->x_char = 0;
else
uart_send_xchar(tty, START_CHAR(tty));
}
if (tty->termios->c_cflag & CRTSCTS)
uart_set_mctrl(port, TIOCM_RTS);
}
static int uart_get_info(struct uart_state *state,
struct serial_struct __user *retinfo)
{
struct uart_port *port = state->port;
struct serial_struct tmp;
memset(&tmp, 0, sizeof(tmp));
tmp.type = port->type;
tmp.line = port->line;
tmp.port = port->iobase;
if (HIGH_BITS_OFFSET)
tmp.port_high = (long) port->iobase >> HIGH_BITS_OFFSET;
tmp.irq = port->irq;
tmp.flags = port->flags;
tmp.xmit_fifo_size = port->fifosize;
tmp.baud_base = port->uartclk / 16;
tmp.close_delay = state->close_delay / 10;
tmp.closing_wait = state->closing_wait == USF_CLOSING_WAIT_NONE ?
ASYNC_CLOSING_WAIT_NONE :
state->closing_wait / 10;
tmp.custom_divisor = port->custom_divisor;
tmp.hub6 = port->hub6;
tmp.io_type = port->iotype;
tmp.iomem_reg_shift = port->regshift;
tmp.iomem_base = (void *)port->mapbase;
if (copy_to_user(retinfo, &tmp, sizeof(*retinfo)))
return -EFAULT;
return 0;
}
static int uart_set_info(struct uart_state *state,
struct serial_struct __user *newinfo)
{
struct serial_struct new_serial;
struct uart_port *port = state->port;
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 (copy_from_user(&new_serial, newinfo, sizeof(new_serial)))
return -EFAULT;
new_port = new_serial.port;
if (HIGH_BITS_OFFSET)
new_port += (unsigned long) new_serial.port_high << HIGH_BITS_OFFSET;
new_serial.irq = irq_canonicalize(new_serial.irq);
close_delay = new_serial.close_delay * 10;
closing_wait = new_serial.closing_wait == ASYNC_CLOSING_WAIT_NONE ?
USF_CLOSING_WAIT_NONE : new_serial.closing_wait * 10;
/*
* This semaphore protects state->count. It is also
* very useful to prevent opens. Also, take the
* port configuration semaphore to make sure that a
* module insertion/removal doesn't change anything
* under us.
*/
mutex_lock(&state->mutex);
change_irq = new_serial.irq != port->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 = new_port != port->iobase ||
(unsigned long)new_serial.iomem_base != port->mapbase ||
new_serial.hub6 != port->hub6 ||
new_serial.io_type != port->iotype ||
new_serial.iomem_reg_shift != port->regshift ||
new_serial.type != port->type;
old_flags = port->flags;
new_flags = new_serial.flags;
old_custom_divisor = port->custom_divisor;
if (!capable(CAP_SYS_ADMIN)) {
retval = -EPERM;
if (change_irq || change_port ||
(new_serial.baud_base != port->uartclk / 16) ||
(close_delay != state->close_delay) ||
(closing_wait != state->closing_wait) ||
(new_serial.xmit_fifo_size &&
new_serial.xmit_fifo_size != port->fifosize) ||
(((new_flags ^ old_flags) & ~UPF_USR_MASK) != 0))
goto exit;
port->flags = ((port->flags & ~UPF_USR_MASK) |
(new_flags & UPF_USR_MASK));
port->custom_divisor = new_serial.custom_divisor;
goto check_and_exit;
}
/*
* Ask the low level driver to verify the settings.
*/
if (port->ops->verify_port)
retval = port->ops->verify_port(port, &new_serial);
if ((new_serial.irq >= NR_IRQS) || (new_serial.irq < 0) ||
(new_serial.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 (uart_users(state) > 1)
goto exit;
/*
* We need to shutdown the serial port at the old
* port/type/irq combination.
*/
uart_shutdown(state);
}
if (change_port) {
unsigned long old_iobase, old_mapbase;
unsigned int old_type, old_iotype, old_hub6, old_shift;
old_iobase = port->iobase;
old_mapbase = port->mapbase;
old_type = port->type;
old_hub6 = port->hub6;
old_iotype = port->iotype;
old_shift = port->regshift;
/*
* Free and release old regions
*/
if (old_type != PORT_UNKNOWN)
port->ops->release_port(port);
port->iobase = new_port;
port->type = new_serial.type;
port->hub6 = new_serial.hub6;
port->iotype = new_serial.io_type;
port->regshift = new_serial.iomem_reg_shift;
port->mapbase = (unsigned long)new_serial.iomem_base;
/*
* Claim and map the new regions
*/
if (port->type != PORT_UNKNOWN) {
retval = port->ops->request_port(port);
} 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 && old_type != PORT_UNKNOWN) {
port->iobase = old_iobase;
port->type = old_type;
port->hub6 = old_hub6;
port->iotype = old_iotype;
port->regshift = old_shift;
port->mapbase = old_mapbase;
retval = port->ops->request_port(port);
/*
* If we failed to restore the old settings,
* we fail like this.
*/
if (retval)
port->type = PORT_UNKNOWN;
/*
* We failed anyway.
*/
retval = -EBUSY;
goto exit; // Added to return the correct error -Ram Gupta
}
}
port->irq = new_serial.irq;
port->uartclk = new_serial.baud_base * 16;
port->flags = (port->flags & ~UPF_CHANGE_MASK) |
(new_flags & UPF_CHANGE_MASK);
port->custom_divisor = new_serial.custom_divisor;
state->close_delay = close_delay;
state->closing_wait = closing_wait;
if (new_serial.xmit_fifo_size)
port->fifosize = new_serial.xmit_fifo_size;
if (state->info->tty)
state->info->tty->low_latency =
(port->flags & UPF_LOW_LATENCY) ? 1 : 0;
check_and_exit:
retval = 0;
if (port->type == PORT_UNKNOWN)
goto exit;
if (state->info->flags & UIF_INITIALIZED) {
if (((old_flags ^ port->flags) & UPF_SPD_MASK) ||
old_custom_divisor != port->custom_divisor) {
/*
* If they're setting up a custom divisor or speed,
* instead of clearing it, then bitch about it. No
* need to rate-limit; it's CAP_SYS_ADMIN only.
*/
if (port->flags & UPF_SPD_MASK) {
char buf[64];
printk(KERN_NOTICE
"%s sets custom speed on %s. This "
"is deprecated.\n", current->comm,
tty_name(state->info->tty, buf));
}
uart_change_speed(state, NULL);
}
} else
retval = uart_startup(state, 1);
exit:
mutex_unlock(&state->mutex);
return retval;
}
/*
* uart_get_lsr_info - get line status register info.
* Note: uart_ioctl protects us against hangups.
*/
static int uart_get_lsr_info(struct uart_state *state,
unsigned int __user *value)
{
struct uart_port *port = state->port;
unsigned int result;
result = port->ops->tx_empty(port);
/*
* If we're about to load something into the transmit
* register, we'll pretend the transmitter isn't empty to
* avoid a race condition (depending on when the transmit
* interrupt happens).
*/
if (port->x_char ||
((uart_circ_chars_pending(&state->info->xmit) > 0) &&
!state->info->tty->stopped && !state->info->tty->hw_stopped))
result &= ~TIOCSER_TEMT;
return put_user(result, value);
}
static int uart_tiocmget(struct tty_struct *tty, struct file *file)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->port;
int result = -EIO;
mutex_lock(&state->mutex);
if ((!file || !tty_hung_up_p(file)) &&
!(tty->flags & (1 << TTY_IO_ERROR))) {
result = port->mctrl;
spin_lock_irq(&port->lock);
result |= port->ops->get_mctrl(port);
spin_unlock_irq(&port->lock);
}
mutex_unlock(&state->mutex);
return result;
}
static int
uart_tiocmset(struct tty_struct *tty, struct file *file,
unsigned int set, unsigned int clear)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->port;
int ret = -EIO;
mutex_lock(&state->mutex);
if ((!file || !tty_hung_up_p(file)) &&
!(tty->flags & (1 << TTY_IO_ERROR))) {
uart_update_mctrl(port, set, clear);
ret = 0;
}
mutex_unlock(&state->mutex);
return ret;
}
static void uart_break_ctl(struct tty_struct *tty, int break_state)
{
struct uart_state *state = tty->driver_data;
struct uart_port *port = state->port;
BUG_ON(!kernel_locked());
mutex_lock(&state->mutex);
if (port->type != PORT_UNKNOWN)
port->ops->break_ctl(port, break_state);
mutex_unlock(&state->mutex);
}
static int uart_do_autoconfig(struct uart_state *state)
{
struct uart_port *port = state->port;
int flags, ret;
if (!capable(CAP_SYS_ADMIN))
return -EPERM;
/*
* Take the per-port semaphore. This prevents count from
* changing, and hence any extra opens of the port while
* we're auto-configuring.
*/
if (mutex_lock_interruptible(&state->mutex))
return -ERESTARTSYS;
ret = -EBUSY;
if (uart_users(state) == 1) {
uart_shutdown(state);
/*
* If we already have a port type configured,
* we must release its resources.
*/
if (port->type != PORT_UNKNOWN)
port->ops->release_port(port);
flags = UART_CONFIG_TYPE;
if (port->flags & UPF_AUTO_IRQ)
flags |= UART_CONFIG_IRQ;
/*
* This will claim the ports resources if
* a port is found.
*/
port->ops->config_port(port, flags);
ret = uart_startup(state, 1);
}
mutex_unlock(&state->mutex);
return ret;
}
/*
* Wait for any of the 4 modem inputs (DCD,RI,DSR,CTS) to change
* - mask passed in arg for lines of interest
* (use |'ed TIOCM_RNG/DSR/CD/CTS for masking)
* Caller should use TIOCGICOUNT to see which one it was
*/
static int
uart_wait_modem_status(struct uart_state *state, unsigned long arg)
{
struct uart_port *port = state->port;
DECLARE_WAITQUEUE(wait, current);
struct uart_icount cprev, cnow;
int ret;
/*
* note the counters on entry
*/
spin_lock_irq(&port->lock);
memcpy(&cprev, &port->icount, sizeof(struct uart_icount));
/*
* Force modem status interrupts on
*/
port->ops->enable_ms(port);
spin_unlock_irq(&port->lock);
add_wait_queue(&state->info->delta_msr_wait, &wait);
for (;;) {
spin_lock_irq(&port->lock);
memcpy(&cnow, &port->icount, sizeof(struct uart_icount));
spin_unlock_irq(&port->lock);
set_current_state(TASK_INTERRUPTIBLE);
if (((arg & TIOCM_RNG) && (cnow.rng != cprev.rng)) ||
((arg & TIOCM_DSR) && (cnow.dsr != cprev.dsr)) ||
((arg & TIOCM_CD) && (cnow.dcd != cprev.dcd)) ||
((arg & TIOCM_CTS) && (cnow.cts != cprev.cts))) {