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linux/drivers/char/generic_serial.c

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/*
* generic_serial.c
*
* Copyright (C) 1998/1999 R.E.Wolff@BitWizard.nl
*
* written for the SX serial driver.
* Contains the code that should be shared over all the serial drivers.
*
* Credit for the idea to do it this way might go to Alan Cox.
*
*
* Version 0.1 -- December, 1998. Initial version.
* Version 0.2 -- March, 1999. Some more routines. Bugfixes. Etc.
* Version 0.5 -- August, 1999. Some more fixes. Reformat for Linus.
*
* BitWizard is actively maintaining this file. We sometimes find
* that someone submitted changes to this file. We really appreciate
* your help, but please submit changes through us. We're doing our
* best to be responsive. -- REW
* */
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/tty.h>
#include <linux/serial.h>
#include <linux/mm.h>
#include <linux/generic_serial.h>
#include <linux/interrupt.h>
#include <linux/tty_flip.h>
#include <linux/delay.h>
#include <asm/semaphore.h>
#include <asm/uaccess.h>
#define DEBUG
static int gs_debug;
#ifdef DEBUG
#define gs_dprintk(f, str...) if (gs_debug & f) printk (str)
#else
#define gs_dprintk(f, str...) /* nothing */
#endif
#define func_enter() gs_dprintk (GS_DEBUG_FLOW, "gs: enter %s\n", __FUNCTION__)
#define func_exit() gs_dprintk (GS_DEBUG_FLOW, "gs: exit %s\n", __FUNCTION__)
#define RS_EVENT_WRITE_WAKEUP 1
module_param(gs_debug, int, 0644);
void gs_put_char(struct tty_struct * tty, unsigned char ch)
{
struct gs_port *port;
func_enter ();
if (!tty) return;
port = tty->driver_data;
if (!port) return;
if (! (port->flags & ASYNC_INITIALIZED)) return;
/* Take a lock on the serial tranmit buffer! */
mutex_lock(& port->port_write_mutex);
if (port->xmit_cnt >= SERIAL_XMIT_SIZE - 1) {
/* Sorry, buffer is full, drop character. Update statistics???? -- REW */
mutex_unlock(&port->port_write_mutex);
return;
}
port->xmit_buf[port->xmit_head++] = ch;
port->xmit_head &= SERIAL_XMIT_SIZE - 1;
port->xmit_cnt++; /* Characters in buffer */
mutex_unlock(&port->port_write_mutex);
func_exit ();
}
/*
> Problems to take into account are:
> -1- Interrupts that empty part of the buffer.
> -2- page faults on the access to userspace.
> -3- Other processes that are also trying to do a "write".
*/
int gs_write(struct tty_struct * tty,
const unsigned char *buf, int count)
{
struct gs_port *port;
int c, total = 0;
int t;
func_enter ();
if (!tty) return 0;
port = tty->driver_data;
if (!port) return 0;
if (! (port->flags & ASYNC_INITIALIZED))
return 0;
/* get exclusive "write" access to this port (problem 3) */
/* This is not a spinlock because we can have a disk access (page
fault) in copy_from_user */
mutex_lock(& port->port_write_mutex);
while (1) {
c = count;
/* This is safe because we "OWN" the "head". Noone else can
change the "head": we own the port_write_mutex. */
/* Don't overrun the end of the buffer */
t = SERIAL_XMIT_SIZE - port->xmit_head;
if (t < c) c = t;
/* This is safe because the xmit_cnt can only decrease. This
would increase "t", so we might copy too little chars. */
/* Don't copy past the "head" of the buffer */
t = SERIAL_XMIT_SIZE - 1 - port->xmit_cnt;
if (t < c) c = t;
/* Can't copy more? break out! */
if (c <= 0) break;
memcpy (port->xmit_buf + port->xmit_head, buf, c);
port -> xmit_cnt += c;
port -> xmit_head = (port->xmit_head + c) & (SERIAL_XMIT_SIZE -1);
buf += c;
count -= c;
total += c;
}
mutex_unlock(& port->port_write_mutex);
gs_dprintk (GS_DEBUG_WRITE, "write: interrupts are %s\n",
(port->flags & GS_TX_INTEN)?"enabled": "disabled");
if (port->xmit_cnt &&
!tty->stopped &&
!tty->hw_stopped &&
!(port->flags & GS_TX_INTEN)) {
port->flags |= GS_TX_INTEN;
port->rd->enable_tx_interrupts (port);
}
func_exit ();
return total;
}
int gs_write_room(struct tty_struct * tty)
{
struct gs_port *port = tty->driver_data;
int ret;
func_enter ();
ret = SERIAL_XMIT_SIZE - port->xmit_cnt - 1;
if (ret < 0)
ret = 0;
func_exit ();
return ret;
}
int gs_chars_in_buffer(struct tty_struct *tty)
{
struct gs_port *port = tty->driver_data;
func_enter ();
func_exit ();
return port->xmit_cnt;
}
static int gs_real_chars_in_buffer(struct tty_struct *tty)
{
struct gs_port *port;
func_enter ();
if (!tty) return 0;
port = tty->driver_data;
if (!port->rd) return 0;
if (!port->rd->chars_in_buffer) return 0;
func_exit ();
return port->xmit_cnt + port->rd->chars_in_buffer (port);
}
static int gs_wait_tx_flushed (void * ptr, unsigned long timeout)
{
struct gs_port *port = ptr;
unsigned long end_jiffies;
int jiffies_to_transmit, charsleft = 0, rv = 0;
int rcib;
func_enter();
gs_dprintk (GS_DEBUG_FLUSH, "port=%p.\n", port);
if (port) {
gs_dprintk (GS_DEBUG_FLUSH, "xmit_cnt=%x, xmit_buf=%p, tty=%p.\n",
port->xmit_cnt, port->xmit_buf, port->tty);
}
if (!port || port->xmit_cnt < 0 || !port->xmit_buf) {
gs_dprintk (GS_DEBUG_FLUSH, "ERROR: !port, !port->xmit_buf or prot->xmit_cnt < 0.\n");
func_exit();
return -EINVAL; /* This is an error which we don't know how to handle. */
}
rcib = gs_real_chars_in_buffer(port->tty);
if(rcib <= 0) {
gs_dprintk (GS_DEBUG_FLUSH, "nothing to wait for.\n");
func_exit();
return rv;
}
/* stop trying: now + twice the time it would normally take + seconds */
if (timeout == 0) timeout = MAX_SCHEDULE_TIMEOUT;
end_jiffies = jiffies;
if (timeout != MAX_SCHEDULE_TIMEOUT)
end_jiffies += port->baud?(2 * rcib * 10 * HZ / port->baud):0;
end_jiffies += timeout;
gs_dprintk (GS_DEBUG_FLUSH, "now=%lx, end=%lx (%ld).\n",
jiffies, end_jiffies, end_jiffies-jiffies);
/* the expression is actually jiffies < end_jiffies, but that won't
work around the wraparound. Tricky eh? */
while ((charsleft = gs_real_chars_in_buffer (port->tty)) &&
time_after (end_jiffies, jiffies)) {
/* Units check:
chars * (bits/char) * (jiffies /sec) / (bits/sec) = jiffies!
check! */
charsleft += 16; /* Allow 16 chars more to be transmitted ... */
jiffies_to_transmit = port->baud?(1 + charsleft * 10 * HZ / port->baud):0;
/* ^^^ Round up.... */
if (jiffies_to_transmit <= 0) jiffies_to_transmit = 1;
gs_dprintk (GS_DEBUG_FLUSH, "Expect to finish in %d jiffies "
"(%d chars).\n", jiffies_to_transmit, charsleft);
msleep_interruptible(jiffies_to_msecs(jiffies_to_transmit));
if (signal_pending (current)) {
gs_dprintk (GS_DEBUG_FLUSH, "Signal pending. Bombing out: ");
rv = -EINTR;
break;
}
}
gs_dprintk (GS_DEBUG_FLUSH, "charsleft = %d.\n", charsleft);
set_current_state (TASK_RUNNING);
func_exit();
return rv;
}
void gs_flush_buffer(struct tty_struct *tty)
{
struct gs_port *port;
unsigned long flags;
func_enter ();
if (!tty) return;
port = tty->driver_data;
if (!port) return;
/* XXX Would the write semaphore do? */
spin_lock_irqsave (&port->driver_lock, flags);
port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
spin_unlock_irqrestore (&port->driver_lock, flags);
tty_wakeup(tty);
func_exit ();
}
void gs_flush_chars(struct tty_struct * tty)
{
struct gs_port *port;
func_enter ();
if (!tty) return;
port = tty->driver_data;
if (!port) return;
if (port->xmit_cnt <= 0 || tty->stopped || tty->hw_stopped ||
!port->xmit_buf) {
func_exit ();
return;
}
/* Beats me -- REW */
port->flags |= GS_TX_INTEN;
port->rd->enable_tx_interrupts (port);
func_exit ();
}
void gs_stop(struct tty_struct * tty)
{
struct gs_port *port;
func_enter ();
if (!tty) return;
port = tty->driver_data;
if (!port) return;
if (port->xmit_cnt &&
port->xmit_buf &&
(port->flags & GS_TX_INTEN) ) {
port->flags &= ~GS_TX_INTEN;
port->rd->disable_tx_interrupts (port);
}
func_exit ();
}
void gs_start(struct tty_struct * tty)
{
struct gs_port *port;
if (!tty) return;
port = tty->driver_data;
if (!port) return;
if (port->xmit_cnt &&
port->xmit_buf &&
!(port->flags & GS_TX_INTEN) ) {
port->flags |= GS_TX_INTEN;
port->rd->enable_tx_interrupts (port);
}
func_exit ();
}
static void gs_shutdown_port (struct gs_port *port)
{
unsigned long flags;
func_enter();
if (!port) return;
if (!(port->flags & ASYNC_INITIALIZED))
return;
spin_lock_irqsave(&port->driver_lock, flags);
if (port->xmit_buf) {
free_page((unsigned long) port->xmit_buf);
port->xmit_buf = NULL;
}
if (port->tty)
set_bit(TTY_IO_ERROR, &port->tty->flags);
port->rd->shutdown_port (port);
port->flags &= ~ASYNC_INITIALIZED;
spin_unlock_irqrestore(&port->driver_lock, flags);
func_exit();
}
void gs_hangup(struct tty_struct *tty)
{
struct gs_port *port;
func_enter ();
if (!tty) return;
port = tty->driver_data;
tty = port->tty;
if (!tty)
return;
gs_shutdown_port (port);
port->flags &= ~(ASYNC_NORMAL_ACTIVE|GS_ACTIVE);
port->tty = NULL;
port->count = 0;
wake_up_interruptible(&port->open_wait);
func_exit ();
}
int gs_block_til_ready(void *port_, struct file * filp)
{
struct gs_port *port = port_;
DECLARE_WAITQUEUE(wait, current);
int retval;
int do_clocal = 0;
int CD;
struct tty_struct *tty;
unsigned long flags;
func_enter ();
if (!port) return 0;
tty = port->tty;
if (!tty) return 0;
gs_dprintk (GS_DEBUG_BTR, "Entering gs_block_till_ready.\n");
/*
* If the device is in the middle of being closed, then block
* until it's done, and then try again.
*/
if (tty_hung_up_p(filp) || port->flags & ASYNC_CLOSING) {
interruptible_sleep_on(&port->close_wait);
if (port->flags & ASYNC_HUP_NOTIFY)
return -EAGAIN;
else
return -ERESTARTSYS;
}
gs_dprintk (GS_DEBUG_BTR, "after hung up\n");
/*
* If non-blocking mode is set, or the port is not enabled,
* then make the check up front and then exit.
*/
if ((filp->f_flags & O_NONBLOCK) ||
(tty->flags & (1 << TTY_IO_ERROR))) {
port->flags |= ASYNC_NORMAL_ACTIVE;
return 0;
}
gs_dprintk (GS_DEBUG_BTR, "after nonblock\n");
if (C_CLOCAL(tty))
do_clocal = 1;
/*
* Block waiting for the carrier detect and the line to become
* free (i.e., not in use by the callout). While we are in
* this loop, port->count is dropped by one, so that
* rs_close() knows when to free things. We restore it upon
* exit, either normal or abnormal.
*/
retval = 0;
add_wait_queue(&port->open_wait, &wait);
gs_dprintk (GS_DEBUG_BTR, "after add waitq.\n");
spin_lock_irqsave(&port->driver_lock, flags);
if (!tty_hung_up_p(filp)) {
port->count--;
}
spin_unlock_irqrestore(&port->driver_lock, flags);
port->blocked_open++;
while (1) {
CD = port->rd->get_CD (port);
gs_dprintk (GS_DEBUG_BTR, "CD is now %d.\n", CD);
set_current_state (TASK_INTERRUPTIBLE);
if (tty_hung_up_p(filp) ||
!(port->flags & ASYNC_INITIALIZED)) {
if (port->flags & ASYNC_HUP_NOTIFY)
retval = -EAGAIN;
else
retval = -ERESTARTSYS;
break;
}
if (!(port->flags & ASYNC_CLOSING) &&
(do_clocal || CD))
break;
gs_dprintk (GS_DEBUG_BTR, "signal_pending is now: %d (%lx)\n",
(int)signal_pending (current), *(long*)(&current->blocked));
if (signal_pending(current)) {
retval = -ERESTARTSYS;
break;
}
schedule();
}
gs_dprintk (GS_DEBUG_BTR, "Got out of the loop. (%d)\n",
port->blocked_open);
set_current_state (TASK_RUNNING);
remove_wait_queue(&port->open_wait, &wait);
if (!tty_hung_up_p(filp)) {
port->count++;
}
port->blocked_open--;
if (retval)
return retval;
port->flags |= ASYNC_NORMAL_ACTIVE;
func_exit ();
return 0;
}
void gs_close(struct tty_struct * tty, struct file * filp)
{
unsigned long flags;
struct gs_port *port;
func_enter ();
if (!tty) return;
port = (struct gs_port *) tty->driver_data;
if (!port) return;
if (!port->tty) {
/* This seems to happen when this is called from vhangup. */
gs_dprintk (GS_DEBUG_CLOSE, "gs: Odd: port->tty is NULL\n");
port->tty = tty;
}
spin_lock_irqsave(&port->driver_lock, flags);
if (tty_hung_up_p(filp)) {
spin_unlock_irqrestore(&port->driver_lock, flags);
if (port->rd->hungup)
port->rd->hungup (port);
func_exit ();
return;
}
if ((tty->count == 1) && (port->count != 1)) {
printk(KERN_ERR "gs: gs_close port %p: bad port count;"
" tty->count is 1, port count is %d\n", port, port->count);
port->count = 1;
}
if (--port->count < 0) {
printk(KERN_ERR "gs: gs_close port %p: bad port count: %d\n", port, port->count);
port->count = 0;
}
if (port->count) {
gs_dprintk(GS_DEBUG_CLOSE, "gs_close port %p: count: %d\n", port, port->count);
spin_unlock_irqrestore(&port->driver_lock, flags);
func_exit ();
return;
}
port->flags |= ASYNC_CLOSING;
/*
* Now we wait for the transmit buffer to clear; and we notify
* the line discipline to only process XON/XOFF characters.
*/
tty->closing = 1;
/* if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
tty_wait_until_sent(tty, port->closing_wait); */
/*
* At this point we stop accepting input. To do this, we
* disable the receive line status interrupts, and tell the
* interrupt driver to stop checking the data ready bit in the
* line status register.
*/
port->rd->disable_rx_interrupts (port);
spin_unlock_irqrestore(&port->driver_lock, flags);
/* close has no way of returning "EINTR", so discard return value */
if (port->closing_wait != ASYNC_CLOSING_WAIT_NONE)
gs_wait_tx_flushed (port, port->closing_wait);
port->flags &= ~GS_ACTIVE;
if (tty->driver->flush_buffer)
tty->driver->flush_buffer(tty);
tty_ldisc_flush(tty);
tty->closing = 0;
port->event = 0;
port->rd->close (port);
port->rd->shutdown_port (port);
port->tty = NULL;
if (port->blocked_open) {
if (port->close_delay) {
spin_unlock_irqrestore(&port->driver_lock, flags);
msleep_interruptible(jiffies_to_msecs(port->close_delay));
spin_lock_irqsave(&port->driver_lock, flags);
}
wake_up_interruptible(&port->open_wait);
}
port->flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CLOSING | ASYNC_INITIALIZED);
wake_up_interruptible(&port->close_wait);
func_exit ();
}
void gs_set_termios (struct tty_struct * tty,
struct ktermios * old_termios)
{
struct gs_port *port;
int baudrate, tmp, rv;
struct ktermios *tiosp;
func_enter();
if (!tty) return;
port = tty->driver_data;
if (!port) return;
if (!port->tty) {
/* This seems to happen when this is called after gs_close. */
gs_dprintk (GS_DEBUG_TERMIOS, "gs: Odd: port->tty is NULL\n");
port->tty = tty;
}
tiosp = tty->termios;
if (gs_debug & GS_DEBUG_TERMIOS) {
gs_dprintk (GS_DEBUG_TERMIOS, "termios structure (%p):\n", tiosp);
}
if(old_termios && (gs_debug & GS_DEBUG_TERMIOS)) {
if(tiosp->c_iflag != old_termios->c_iflag) printk("c_iflag changed\n");
if(tiosp->c_oflag != old_termios->c_oflag) printk("c_oflag changed\n");
if(tiosp->c_cflag != old_termios->c_cflag) printk("c_cflag changed\n");
if(tiosp->c_lflag != old_termios->c_lflag) printk("c_lflag changed\n");
if(tiosp->c_line != old_termios->c_line) printk("c_line changed\n");
if(!memcmp(tiosp->c_cc, old_termios->c_cc, NCC)) printk("c_cc changed\n");
}
baudrate = tty_get_baud_rate(tty);
if ((tiosp->c_cflag & CBAUD) == B38400) {
if ( (port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
baudrate = 57600;
else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
baudrate = 115200;
else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
baudrate = 230400;
else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
baudrate = 460800;
else if ((port->flags & ASYNC_SPD_MASK) == ASYNC_SPD_CUST)
baudrate = (port->baud_base / port->custom_divisor);
}
/* I recommend using THIS instead of the mess in termios (and
duplicating the above code). Next we should create a clean
interface towards this variable. If your card supports arbitrary
baud rates, (e.g. CD1400 or 16550 based cards) then everything
will be very easy..... */
port->baud = baudrate;
/* Two timer ticks seems enough to wakeup something like SLIP driver */
/* Baudrate/10 is cps. Divide by HZ to get chars per tick. */
tmp = (baudrate / 10 / HZ) * 2;
if (tmp < 0) tmp = 0;
if (tmp >= SERIAL_XMIT_SIZE) tmp = SERIAL_XMIT_SIZE-1;
port->wakeup_chars = tmp;
/* We should really wait for the characters to be all sent before
changing the settings. -- CAL */
rv = gs_wait_tx_flushed (port, MAX_SCHEDULE_TIMEOUT);
if (rv < 0) return /* rv */;
rv = port->rd->set_real_termios(port);
if (rv < 0) return /* rv */;
if ((!old_termios ||
(old_termios->c_cflag & CRTSCTS)) &&
!( tiosp->c_cflag & CRTSCTS)) {
tty->stopped = 0;
gs_start(tty);
}
#ifdef tytso_patch_94Nov25_1726
/* This "makes sense", Why is it commented out? */
if (!(old_termios->c_cflag & CLOCAL) &&
(tty->termios->c_cflag & CLOCAL))
wake_up_interruptible(&port->gs.open_wait);
#endif
func_exit();
return /* 0 */;
}
/* Must be called with interrupts enabled */
int gs_init_port(struct gs_port *port)
{
unsigned long flags;
func_enter ();
if (port->flags & ASYNC_INITIALIZED) {
func_exit ();
return 0;
}
if (!port->xmit_buf) {
/* We may sleep in get_zeroed_page() */
unsigned long tmp;
tmp = get_zeroed_page(GFP_KERNEL);
spin_lock_irqsave (&port->driver_lock, flags);
if (port->xmit_buf)
free_page (tmp);
else
port->xmit_buf = (unsigned char *) tmp;
spin_unlock_irqrestore(&port->driver_lock, flags);
if (!port->xmit_buf) {
func_exit ();
return -ENOMEM;
}
}
spin_lock_irqsave (&port->driver_lock, flags);
if (port->tty)
clear_bit(TTY_IO_ERROR, &port->tty->flags);
mutex_init(&port->port_write_mutex);
port->xmit_cnt = port->xmit_head = port->xmit_tail = 0;
spin_unlock_irqrestore(&port->driver_lock, flags);
gs_set_termios(port->tty, NULL);
spin_lock_irqsave (&port->driver_lock, flags);
port->flags |= ASYNC_INITIALIZED;
port->flags &= ~GS_TX_INTEN;
spin_unlock_irqrestore(&port->driver_lock, flags);
func_exit ();
return 0;
}
int gs_setserial(struct gs_port *port, struct serial_struct __user *sp)
{
struct serial_struct sio;
if (copy_from_user(&sio, sp, sizeof(struct serial_struct)))
return(-EFAULT);
if (!capable(CAP_SYS_ADMIN)) {
if ((sio.baud_base != port->baud_base) ||
(sio.close_delay != port->close_delay) ||
((sio.flags & ~ASYNC_USR_MASK) !=
(port->flags & ~ASYNC_USR_MASK)))
return(-EPERM);
}
port->flags = (port->flags & ~ASYNC_USR_MASK) |
(sio.flags & ASYNC_USR_MASK);
port->baud_base = sio.baud_base;
port->close_delay = sio.close_delay;
port->closing_wait = sio.closing_wait;
port->custom_divisor = sio.custom_divisor;
gs_set_termios (port->tty, NULL);
return 0;
}
/*****************************************************************************/
/*
* Generate the serial struct info.
*/
int gs_getserial(struct gs_port *port, struct serial_struct __user *sp)
{
struct serial_struct sio;
memset(&sio, 0, sizeof(struct serial_struct));
sio.flags = port->flags;
sio.baud_base = port->baud_base;
sio.close_delay = port->close_delay;
sio.closing_wait = port->closing_wait;
sio.custom_divisor = port->custom_divisor;
sio.hub6 = 0;
/* If you want you can override these. */
sio.type = PORT_UNKNOWN;
sio.xmit_fifo_size = -1;
sio.line = -1;
sio.port = -1;
sio.irq = -1;
if (port->rd->getserial)
port->rd->getserial (port, &sio);
if (copy_to_user(sp, &sio, sizeof(struct serial_struct)))
return -EFAULT;
return 0;
}
void gs_got_break(struct gs_port *port)
{
func_enter ();
tty_insert_flip_char(port->tty, 0, TTY_BREAK);
tty_schedule_flip(port->tty);
if (port->flags & ASYNC_SAK) {
do_SAK (port->tty);
}
func_exit ();
}
EXPORT_SYMBOL(gs_put_char);
EXPORT_SYMBOL(gs_write);
EXPORT_SYMBOL(gs_write_room);
EXPORT_SYMBOL(gs_chars_in_buffer);
EXPORT_SYMBOL(gs_flush_buffer);
EXPORT_SYMBOL(gs_flush_chars);
EXPORT_SYMBOL(gs_stop);
EXPORT_SYMBOL(gs_start);
EXPORT_SYMBOL(gs_hangup);
EXPORT_SYMBOL(gs_block_til_ready);
EXPORT_SYMBOL(gs_close);
EXPORT_SYMBOL(gs_set_termios);
EXPORT_SYMBOL(gs_init_port);
EXPORT_SYMBOL(gs_setserial);
EXPORT_SYMBOL(gs_getserial);
EXPORT_SYMBOL(gs_got_break);
MODULE_LICENSE("GPL");
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