serial.c

linux 内核源代码

	printk(KERN_INFO "gs_module_init: %s %s loaded\n", GS_LONG_NAME, GS_VERSION_STR);
	return 0;
}

/*
* gs_module_exit
*
* Unregister as a tty driver and a USB gadget driver.
*/
static void __exit gs_module_exit(void)
{
	tty_unregister_driver(gs_tty_driver);
	put_tty_driver(gs_tty_driver);
	usb_gadget_unregister_driver(&gs_gadget_driver);

	printk(KERN_INFO "gs_module_exit: %s %s unloaded\n", GS_LONG_NAME, GS_VERSION_STR);
}

/* TTY Driver */

/*
 * gs_open
 */
static int gs_open(struct tty_struct *tty, struct file *file)
{
	int port_num;
	unsigned long flags;
	struct gs_port *port;
	struct gs_dev *dev;
	struct gs_buf *buf;
	struct mutex *mtx;
	int ret;

	port_num = tty->index;

	gs_debug("gs_open: (%d,%p,%p)\n", port_num, tty, file);

	if (port_num < 0 || port_num >= GS_NUM_PORTS) {
		printk(KERN_ERR "gs_open: (%d,%p,%p) invalid port number\n",
			port_num, tty, file);
		return -ENODEV;
	}

	dev = gs_device;

	if (dev == NULL) {
		printk(KERN_ERR "gs_open: (%d,%p,%p) NULL device pointer\n",
			port_num, tty, file);
		return -ENODEV;
	}

	mtx = &gs_open_close_lock[port_num];
	if (mutex_lock_interruptible(mtx)) {
		printk(KERN_ERR
		"gs_open: (%d,%p,%p) interrupted waiting for mutex\n",
			port_num, tty, file);
		return -ERESTARTSYS;
	}

	spin_lock_irqsave(&dev->dev_lock, flags);

	if (dev->dev_config == GS_NO_CONFIG_ID) {
		printk(KERN_ERR
			"gs_open: (%d,%p,%p) device is not connected\n",
			port_num, tty, file);
		ret = -ENODEV;
		goto exit_unlock_dev;
	}

	port = dev->dev_port[port_num];

	if (port == NULL) {
		printk(KERN_ERR "gs_open: (%d,%p,%p) NULL port pointer\n",
			port_num, tty, file);
		ret = -ENODEV;
		goto exit_unlock_dev;
	}

	spin_lock(&port->port_lock);
	spin_unlock(&dev->dev_lock);

	if (port->port_dev == NULL) {
		printk(KERN_ERR "gs_open: (%d,%p,%p) port disconnected (1)\n",
			port_num, tty, file);
		ret = -EIO;
		goto exit_unlock_port;
	}

	if (port->port_open_count > 0) {
		++port->port_open_count;
		gs_debug("gs_open: (%d,%p,%p) already open\n",
			port_num, tty, file);
		ret = 0;
		goto exit_unlock_port;
	}

	tty->driver_data = NULL;

	/* mark port as in use, we can drop port lock and sleep if necessary */
	port->port_in_use = 1;

	/* allocate write buffer on first open */
	if (port->port_write_buf == NULL) {
		spin_unlock_irqrestore(&port->port_lock, flags);
		buf = gs_buf_alloc(write_buf_size, GFP_KERNEL);
		spin_lock_irqsave(&port->port_lock, flags);

		/* might have been disconnected while asleep, check */
		if (port->port_dev == NULL) {
			printk(KERN_ERR
				"gs_open: (%d,%p,%p) port disconnected (2)\n",
				port_num, tty, file);
			port->port_in_use = 0;
			ret = -EIO;
			goto exit_unlock_port;
		}

		if ((port->port_write_buf=buf) == NULL) {
			printk(KERN_ERR "gs_open: (%d,%p,%p) cannot allocate port write buffer\n",
				port_num, tty, file);
			port->port_in_use = 0;
			ret = -ENOMEM;
			goto exit_unlock_port;
		}

	}

	/* wait for carrier detect (not implemented) */

	/* might have been disconnected while asleep, check */
	if (port->port_dev == NULL) {
		printk(KERN_ERR "gs_open: (%d,%p,%p) port disconnected (3)\n",
			port_num, tty, file);
		port->port_in_use = 0;
		ret = -EIO;
		goto exit_unlock_port;
	}

	tty->driver_data = port;
	port->port_tty = tty;
	port->port_open_count = 1;
	port->port_in_use = 0;

	gs_debug("gs_open: (%d,%p,%p) completed\n", port_num, tty, file);

	ret = 0;

exit_unlock_port:
	spin_unlock_irqrestore(&port->port_lock, flags);
	mutex_unlock(mtx);
	return ret;

exit_unlock_dev:
	spin_unlock_irqrestore(&dev->dev_lock, flags);
	mutex_unlock(mtx);
	return ret;

}

/*
 * gs_close
 */

#define GS_WRITE_FINISHED_EVENT_SAFELY(p)			\
({								\
	int cond;						\
								\
	spin_lock_irq(&(p)->port_lock);				\
	cond = !(p)->port_dev || !gs_buf_data_avail((p)->port_write_buf); \
	spin_unlock_irq(&(p)->port_lock);			\
	cond;							\
})

static void gs_close(struct tty_struct *tty, struct file *file)
{
	struct gs_port *port = tty->driver_data;
	struct mutex *mtx;

	if (port == NULL) {
		printk(KERN_ERR "gs_close: NULL port pointer\n");
		return;
	}

	gs_debug("gs_close: (%d,%p,%p)\n", port->port_num, tty, file);

	mtx = &gs_open_close_lock[port->port_num];
	mutex_lock(mtx);

	spin_lock_irq(&port->port_lock);

	if (port->port_open_count == 0) {
		printk(KERN_ERR
			"gs_close: (%d,%p,%p) port is already closed\n",
			port->port_num, tty, file);
		goto exit;
	}

	if (port->port_open_count > 1) {
		--port->port_open_count;
		goto exit;
	}

	/* free disconnected port on final close */
	if (port->port_dev == NULL) {
		kfree(port);
		goto exit;
	}

	/* mark port as closed but in use, we can drop port lock */
	/* and sleep if necessary */
	port->port_in_use = 1;
	port->port_open_count = 0;

	/* wait for write buffer to drain, or */
	/* at most GS_CLOSE_TIMEOUT seconds */
	if (gs_buf_data_avail(port->port_write_buf) > 0) {
		spin_unlock_irq(&port->port_lock);
		wait_event_interruptible_timeout(port->port_write_wait,
					GS_WRITE_FINISHED_EVENT_SAFELY(port),
					GS_CLOSE_TIMEOUT * HZ);
		spin_lock_irq(&port->port_lock);
	}

	/* free disconnected port on final close */
	/* (might have happened during the above sleep) */
	if (port->port_dev == NULL) {
		kfree(port);
		goto exit;
	}

	gs_buf_clear(port->port_write_buf);

	tty->driver_data = NULL;
	port->port_tty = NULL;
	port->port_in_use = 0;

	gs_debug("gs_close: (%d,%p,%p) completed\n",
		port->port_num, tty, file);

exit:
	spin_unlock_irq(&port->port_lock);
	mutex_unlock(mtx);
}

/*
 * gs_write
 */
static int gs_write(struct tty_struct *tty, const unsigned char *buf, int count)
{
	unsigned long flags;
	struct gs_port *port = tty->driver_data;
	int ret;

	if (port == NULL) {
		printk(KERN_ERR "gs_write: NULL port pointer\n");
		return -EIO;
	}

	gs_debug("gs_write: (%d,%p) writing %d bytes\n", port->port_num, tty,
		count);

	if (count == 0)
		return 0;

	spin_lock_irqsave(&port->port_lock, flags);

	if (port->port_dev == NULL) {
		printk(KERN_ERR "gs_write: (%d,%p) port is not connected\n",
			port->port_num, tty);
		ret = -EIO;
		goto exit;
	}

	if (port->port_open_count == 0) {
		printk(KERN_ERR "gs_write: (%d,%p) port is closed\n",
			port->port_num, tty);
		ret = -EBADF;
		goto exit;
	}

	count = gs_buf_put(port->port_write_buf, buf, count);

	spin_unlock_irqrestore(&port->port_lock, flags);

	gs_send(gs_device);

	gs_debug("gs_write: (%d,%p) wrote %d bytes\n", port->port_num, tty,
		count);

	return count;

exit:
	spin_unlock_irqrestore(&port->port_lock, flags);
	return ret;
}

/*
 * gs_put_char
 */
static void gs_put_char(struct tty_struct *tty, unsigned char ch)
{
	unsigned long flags;
	struct gs_port *port = tty->driver_data;

	if (port == NULL) {
		printk(KERN_ERR "gs_put_char: NULL port pointer\n");
		return;
	}

	gs_debug("gs_put_char: (%d,%p) char=0x%x, called from %p\n",
		port->port_num, tty, ch, __builtin_return_address(0));

	spin_lock_irqsave(&port->port_lock, flags);

	if (port->port_dev == NULL) {
		printk(KERN_ERR "gs_put_char: (%d,%p) port is not connected\n",
			port->port_num, tty);
		goto exit;
	}

	if (port->port_open_count == 0) {
		printk(KERN_ERR "gs_put_char: (%d,%p) port is closed\n",
			port->port_num, tty);
		goto exit;
	}

	gs_buf_put(port->port_write_buf, &ch, 1);

exit:
	spin_unlock_irqrestore(&port->port_lock, flags);
}

/*
 * gs_flush_chars
 */
static void gs_flush_chars(struct tty_struct *tty)
{
	unsigned long flags;
	struct gs_port *port = tty->driver_data;

	if (port == NULL) {
		printk(KERN_ERR "gs_flush_chars: NULL port pointer\n");
		return;
	}

	gs_debug("gs_flush_chars: (%d,%p)\n", port->port_num, tty);

	spin_lock_irqsave(&port->port_lock, flags);

	if (port->port_dev == NULL) {
		printk(KERN_ERR
			"gs_flush_chars: (%d,%p) port is not connected\n",
			port->port_num, tty);
		goto exit;
	}

	if (port->port_open_count == 0) {
		printk(KERN_ERR "gs_flush_chars: (%d,%p) port is closed\n",
			port->port_num, tty);
		goto exit;
	}

	spin_unlock_irqrestore(&port->port_lock, flags);

	gs_send(gs_device);

	return;

exit:
	spin_unlock_irqrestore(&port->port_lock, flags);
}

/*
 * gs_write_room
 */
static int gs_write_room(struct tty_struct *tty)
{

	int room = 0;
	unsigned long flags;
	struct gs_port *port = tty->driver_data;


	if (port == NULL)
		return 0;

	spin_lock_irqsave(&port->port_lock, flags);

	if (port->port_dev != NULL && port->port_open_count > 0
	&& port->port_write_buf != NULL)
		room = gs_buf_space_avail(port->port_write_buf);

	spin_unlock_irqrestore(&port->port_lock, flags);

	gs_debug("gs_write_room: (%d,%p) room=%d\n",
		port->port_num, tty, room);

	return room;
}

/*
 * gs_chars_in_buffer
 */
static int gs_chars_in_buffer(struct tty_struct *tty)
{
	int chars = 0;
	unsigned long flags;
	struct gs_port *port = tty->driver_data;

	if (port == NULL)
		return 0;

	spin_lock_irqsave(&port->port_lock, flags);

	if (port->port_dev != NULL && port->port_open_count > 0
	&& port->port_write_buf != NULL)
		chars = gs_buf_data_avail(port->port_write_buf);

	spin_unlock_irqrestore(&port->port_lock, flags);

	gs_debug("gs_chars_in_buffer: (%d,%p) chars=%d\n",
		port->port_num, tty, chars);

	return chars;
}

/*
 * gs_throttle
 */
static void gs_throttle(struct tty_struct *tty)
{
}

/*
 * gs_unthrottle
 */
static void gs_unthrottle(struct tty_struct *tty)
{
}

/*
 * gs_break
 */
static void gs_break(struct tty_struct *tty, int break_state)
{
}

/*
 * gs_ioctl
 */
static int gs_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg)
{
	struct gs_port *port = tty->driver_data;

	if (port == NULL) {
		printk(KERN_ERR "gs_ioctl: NULL port pointer\n");
		return -EIO;
	}

	gs_debug("gs_ioctl: (%d,%p,%p) cmd=0x%4.4x, arg=%lu\n",
		port->port_num, tty, file, cmd, arg);

	/* handle ioctls */

	/* could not handle ioctl */
	return -ENOIOCTLCMD;
}

/*
 * gs_set_termios
 */
static void gs_set_termios(struct tty_struct *tty, struct ktermios *old)
{
}

/*
* gs_send
*
* This function finds available write requests, calls
* gs_send_packet to fill these packets with data, and
* continues until either there are no more write requests
* available or no more data to send.  This function is
* run whenever data arrives or write requests are available.
*/
static int gs_send(struct gs_dev *dev)
{
	int ret,len;
	unsigned long flags;
	struct usb_ep *ep;
	struct usb_request *req;
	struct gs_req_entry *req_entry;

	if (dev == NULL) {
		printk(KERN_ERR "gs_send: NULL device pointer\n");
		return -ENODEV;
	}

	spin_lock_irqsave(&dev->dev_lock, flags);

	ep = dev->dev_in_ep;

	while(!list_empty(&dev->dev_req_list)) {

		req_entry = list_entry(dev->dev_req_list.next,
			struct gs_req_entry, re_entry);

		req = req_entry->re_req;

		len = gs_send_packet(dev, req->buf, ep->maxpacket);

		if (len > 0) {
			gs_debug_level(3, "gs_send: len=%d, 0x%2.2x "
					"0x%2.2x 0x%2.2x ...\n", len,
					*((unsigned char *)req->buf),
					*((unsigned char *)req->buf+1),
					*((unsigned char *)req->buf+2));
			list_del(&req_entry->re_entry);
			req->length = len;
			spin_unlock_irqrestore(&dev->dev_lock, flags);
			if ((ret=usb_ep_queue(ep, req, GFP_ATOMIC))) {
				printk(KERN_ERR
				"gs_send: cannot queue read request, ret=%d\n",
					ret);
				spin_lock_irqsave(&dev->dev_lock, flags);
				break;
			}
			spin_lock_irqsave(&dev->dev_lock, flags);
		} else {
			break;
		}

	}

	spin_unlock_irqrestore(&dev->dev_lock, flags);

	return 0;
}

/*
 * gs_send_packet
 *
 * If there is data to send, a packet is built in the given
 * buffer and the size is returned.  If there is no data to
 * send, 0 is returned.  If there is any error a negative
 * error number is returned.
 *
 * Called during USB completion routine, on interrupt time.
 *
 * We assume that disconnect will not happen until all completion
 * routines have completed, so we can assume that the dev_port
 * array does not change during the lifetime of this function.
 */
static int gs_send_packet(struct gs_dev *dev, char *packet, unsigned int size)
{
	unsigned int len;
	struct gs_port *port;

	/* TEMPORARY -- only port 0 is supported right now */
	port = dev->dev_port[0];

	if (port == NULL) {
		printk(KERN_ERR
			"gs_send_packet: port=%d, NULL port pointer\n",
			0);
		return -EIO;
	}

	spin_lock(&port->port_lock);

	len = gs_buf_data_avail(port->port_write_buf);
	if (len < size)
		size = len;

	if (size == 0)
		goto exit;

	size = gs_buf_get(port->port_write_buf, packet, size);

	if (port->port_tty)
		wake_up_interruptible(&port->port_tty->write_wait);

exit:
	spin_unlock(&port->port_lock);