android_kernel_xiaomi_sm8350/drivers/char/generic_serial.c
Alan Cox 51383f69ec tty: Remove lots of NULL checks
Many tty drivers contain 'can't happen' checks against NULL pointers passed
in by the tty layer. These have never been possible to occur. Even more
importantly if they ever do occur we want to know as it would be a serious
bug.

Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-13 09:51:44 -07:00

831 lines
20 KiB
C

/*
* 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/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", __func__)
#define func_exit() gs_dprintk (GS_DEBUG_FLOW, "gs: exit %s\n", __func__)
#define RS_EVENT_WRITE_WAKEUP 1
module_param(gs_debug, int, 0644);
int gs_put_char(struct tty_struct * tty, unsigned char ch)
{
struct gs_port *port;
func_enter ();
port = tty->driver_data;
if (!port) return 0;
if (! (port->port.flags & ASYNC_INITIALIZED)) return 0;
/* 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 0;
}
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 ();
return 1;
}
/*
> 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 ();
port = tty->driver_data;
if (!port) return 0;
if (! (port->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->port.flags & GS_TX_INTEN)?"enabled": "disabled");
if (port->xmit_cnt &&
!tty->stopped &&
!tty->hw_stopped &&
!(port->port.flags & GS_TX_INTEN)) {
port->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 ();
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->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->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->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 ();
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 ();
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->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 ();
port = tty->driver_data;
if (!port) return;
if (port->xmit_cnt &&
port->xmit_buf &&
(port->port.flags & GS_TX_INTEN) ) {
port->port.flags &= ~GS_TX_INTEN;
port->rd->disable_tx_interrupts (port);
}
func_exit ();
}
void gs_start(struct tty_struct * tty)
{
struct gs_port *port;
port = tty->driver_data;
if (!port) return;
if (port->xmit_cnt &&
port->xmit_buf &&
!(port->port.flags & GS_TX_INTEN) ) {
port->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->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->port.tty)
set_bit(TTY_IO_ERROR, &port->port.tty->flags);
port->rd->shutdown_port (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 ();
port = tty->driver_data;
tty = port->port.tty;
if (!tty)
return;
gs_shutdown_port (port);
port->port.flags &= ~(ASYNC_NORMAL_ACTIVE|GS_ACTIVE);
port->port.tty = NULL;
port->port.count = 0;
wake_up_interruptible(&port->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->port.tty;
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->port.flags & ASYNC_CLOSING) {
interruptible_sleep_on(&port->port.close_wait);
if (port->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->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->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->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->port.count--;
}
spin_unlock_irqrestore(&port->driver_lock, flags);
port->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->port.flags & ASYNC_INITIALIZED)) {
if (port->port.flags & ASYNC_HUP_NOTIFY)
retval = -EAGAIN;
else
retval = -ERESTARTSYS;
break;
}
if (!(port->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->port.blocked_open);
set_current_state (TASK_RUNNING);
remove_wait_queue(&port->port.open_wait, &wait);
if (!tty_hung_up_p(filp)) {
port->port.count++;
}
port->port.blocked_open--;
if (retval)
return retval;
port->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 ();
port = (struct gs_port *) tty->driver_data;
if (!port) return;
if (!port->port.tty) {
/* This seems to happen when this is called from vhangup. */
gs_dprintk (GS_DEBUG_CLOSE, "gs: Odd: port->port.tty is NULL\n");
port->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->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->port.count);
port->port.count = 1;
}
if (--port->port.count < 0) {
printk(KERN_ERR "gs: gs_close port %p: bad port count: %d\n", port, port->port.count);
port->port.count = 0;
}
if (port->port.count) {
gs_dprintk(GS_DEBUG_CLOSE, "gs_close port %p: count: %d\n", port, port->port.count);
spin_unlock_irqrestore(&port->driver_lock, flags);
func_exit ();
return;
}
port->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->port.flags &= ~GS_ACTIVE;
gs_flush_buffer(tty);
tty_ldisc_flush(tty);
tty->closing = 0;
port->event = 0;
port->rd->close (port);
port->rd->shutdown_port (port);
port->port.tty = NULL;
if (port->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->port.open_wait);
}
port->port.flags &= ~(ASYNC_NORMAL_ACTIVE|ASYNC_CLOSING | ASYNC_INITIALIZED);
wake_up_interruptible(&port->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();
port = tty->driver_data;
if (!port) return;
if (!port->port.tty) {
/* This seems to happen when this is called after gs_close. */
gs_dprintk (GS_DEBUG_TERMIOS, "gs: Odd: port->port.tty is NULL\n");
port->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->port.flags & ASYNC_SPD_MASK) == ASYNC_SPD_HI)
baudrate = 57600;
else if ((port->port.flags & ASYNC_SPD_MASK) == ASYNC_SPD_VHI)
baudrate = 115200;
else if ((port->port.flags & ASYNC_SPD_MASK) == ASYNC_SPD_SHI)
baudrate = 230400;
else if ((port->port.flags & ASYNC_SPD_MASK) == ASYNC_SPD_WARP)
baudrate = 460800;
else if ((port->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->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->port.tty)
clear_bit(TTY_IO_ERROR, &port->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->port.tty, NULL);
spin_lock_irqsave (&port->driver_lock, flags);
port->port.flags |= ASYNC_INITIALIZED;
port->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->port.flags & ~ASYNC_USR_MASK)))
return(-EPERM);
}
port->port.flags = (port->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->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->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->port.tty, 0, TTY_BREAK);
tty_schedule_flip(port->port.tty);
if (port->port.flags & ASYNC_SAK) {
do_SAK (port->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");