simserial.c

linux内核源码

/*
 * Simulated Serial Driver (fake serial)
 *
 * This driver is mostly used for bringup purposes and will go away.
 * It has a strong dependency on the system console. All outputs
 * are rerouted to the same facility as the one used by printk which, in our
 * case means sys_sim.c console (goes via the simulator). The code hereafter
 * is completely leveraged from the serial.c driver.
 *
 * Copyright (C) 1999-2000, 2002-2003 Hewlett-Packard Co
 *	Stephane Eranian <[e-mail]>
 *	David Mosberger-Tang <[e-mail]>
 *
 * 02/04/00 D. Mosberger	Merged in serial.c bug fixes in rs_close().
 * 02/25/00 D. Mosberger	Synced up with 2.3.99pre-5 version of serial.c.
 * 07/30/02 D. Mosberger	Replace sti()/cli() with explicit spinlocks & local irq masking
 */

#include <linux/init.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/major.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/capability.h>
#include <linux/console.h>
#include <linux/module.h>
#include <linux/serial.h>
#include <linux/serialP.h>
#include <linux/sysrq.h>

#include <asm/irq.h>
#include <asm/hw_irq.h>
#include <asm/uaccess.h>

#undef SIMSERIAL_DEBUG	/* define this to get some debug information */

#define KEYBOARD_INTR	3	/* must match with simulator! */

#define NR_PORTS	1	/* only one port for now */

#define IRQ_T(info) ((info->flags & ASYNC_SHARE_IRQ) ? IRQF_SHARED : IRQF_DISABLED)

#define SSC_GETCHAR	21

extern long ia64_ssc (long, long, long, long, int);
extern void ia64_ssc_connect_irq (long intr, long irq);

static char *serial_name = "SimSerial driver";
static char *serial_version = "0.6";

/*
 * This has been extracted from asm/serial.h. We need one eventually but
 * I don't know exactly what we're going to put in it so just fake one
 * for now.
 */
#define BASE_BAUD ( 1843200 / 16 )

#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST)

/*
 * Most of the values here are meaningless to this particular driver.
 * However some values must be preserved for the code (leveraged from serial.c
 * to work correctly).
 * port must not be 0
 * type must not be UNKNOWN
 * So I picked arbitrary (guess from where?) values instead
 */
static struct serial_state rs_table[NR_PORTS]={
  /* UART CLK   PORT IRQ     FLAGS        */
  { 0, BASE_BAUD, 0x3F8, 0, STD_COM_FLAGS,0,PORT_16550 }  /* ttyS0 */
};

/*
 * Just for the fun of it !
 */
static struct serial_uart_config uart_config[] = {
	{ "unknown", 1, 0 },
	{ "8250", 1, 0 },
	{ "16450", 1, 0 },
	{ "16550", 1, 0 },
	{ "16550A", 16, UART_CLEAR_FIFO | UART_USE_FIFO },
	{ "cirrus", 1, 0 },
	{ "ST16650", 1, UART_CLEAR_FIFO | UART_STARTECH },
	{ "ST16650V2", 32, UART_CLEAR_FIFO | UART_USE_FIFO |
		  UART_STARTECH },
	{ "TI16750", 64, UART_CLEAR_FIFO | UART_USE_FIFO},
	{ NULL, 0}
};

struct tty_driver *hp_simserial_driver;

static struct async_struct *IRQ_ports[NR_IRQS];

static struct console *console;

static unsigned char *tmp_buf;

extern struct console *console_drivers; /* from kernel/printk.c */

/*
 * ------------------------------------------------------------
 * rs_stop() and rs_start()
 *
 * This routines are called before setting or resetting tty->stopped.
 * They enable or disable transmitter interrupts, as necessary.
 * ------------------------------------------------------------
 */
static void rs_stop(struct tty_struct *tty)
{
#ifdef SIMSERIAL_DEBUG
	printk("rs_stop: tty->stopped=%d tty->hw_stopped=%d tty->flow_stopped=%d\n",
		tty->stopped, tty->hw_stopped, tty->flow_stopped);
#endif

}

static void rs_start(struct tty_struct *tty)
{
#ifdef SIMSERIAL_DEBUG
	printk("rs_start: tty->stopped=%d tty->hw_stopped=%d tty->flow_stopped=%d\n",
		tty->stopped, tty->hw_stopped, tty->flow_stopped);
#endif
}

static  void receive_chars(struct tty_struct *tty)
{
	unsigned char ch;
	static unsigned char seen_esc = 0;

	while ( (ch = ia64_ssc(0, 0, 0, 0, SSC_GETCHAR)) ) {
		if ( ch == 27 && seen_esc == 0 ) {
			seen_esc = 1;
			continue;
		} else {
			if ( seen_esc==1 && ch == 'O' ) {
				seen_esc = 2;
				continue;
			} else if ( seen_esc == 2 ) {
				if ( ch == 'P' ) /* F1 */
					show_state();
#ifdef CONFIG_MAGIC_SYSRQ
				if ( ch == 'S' ) { /* F4 */
					do
						ch = ia64_ssc(0, 0, 0, 0,
							      SSC_GETCHAR);
					while (!ch);
					handle_sysrq(ch, NULL);
				}
#endif
				seen_esc = 0;
				continue;
			}
		}
		seen_esc = 0;

		if (tty_insert_flip_char(tty, ch, TTY_NORMAL) == 0)
			break;
	}
	tty_flip_buffer_push(tty);
}

/*
 * This is the serial driver's interrupt routine for a single port
 */
static irqreturn_t rs_interrupt_single(int irq, void *dev_id)
{
	struct async_struct * info;

	/*
	 * I don't know exactly why they don't use the dev_id opaque data
	 * pointer instead of this extra lookup table
	 */
	info = IRQ_ports[irq];
	if (!info || !info->tty) {
		printk(KERN_INFO "simrs_interrupt_single: info|tty=0 info=%p problem\n", info);
		return IRQ_NONE;
	}
	/*
	 * pretty simple in our case, because we only get interrupts
	 * on inbound traffic
	 */
	receive_chars(info->tty);
	return IRQ_HANDLED;
}

/*
 * -------------------------------------------------------------------
 * Here ends the serial interrupt routines.
 * -------------------------------------------------------------------
 */

#if 0
/*
 * not really used in our situation so keep them commented out for now
 */
static DECLARE_TASK_QUEUE(tq_serial); /* used to be at the top of the file */
static void do_serial_bh(void)
{
	run_task_queue(&tq_serial);
	printk(KERN_ERR "do_serial_bh: called\n");
}
#endif

static void do_softint(struct work_struct *private_)
{
	printk(KERN_ERR "simserial: do_softint called\n");
}

static void rs_put_char(struct tty_struct *tty, unsigned char ch)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;
	unsigned long flags;

	if (!tty || !info->xmit.buf) return;

	local_irq_save(flags);
	if (CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE) == 0) {
		local_irq_restore(flags);
		return;
	}
	info->xmit.buf[info->xmit.head] = ch;
	info->xmit.head = (info->xmit.head + 1) & (SERIAL_XMIT_SIZE-1);
	local_irq_restore(flags);
}

static void transmit_chars(struct async_struct *info, int *intr_done)
{
	int count;
	unsigned long flags;


	local_irq_save(flags);

	if (info->x_char) {
		char c = info->x_char;

		console->write(console, &c, 1);

		info->state->icount.tx++;
		info->x_char = 0;

		goto out;
	}

	if (info->xmit.head == info->xmit.tail || info->tty->stopped || info->tty->hw_stopped) {
#ifdef SIMSERIAL_DEBUG
		printk("transmit_chars: head=%d, tail=%d, stopped=%d\n",
		       info->xmit.head, info->xmit.tail, info->tty->stopped);
#endif
		goto out;
	}
	/*
	 * We removed the loop and try to do it in to chunks. We need
	 * 2 operations maximum because it's a ring buffer.
	 *
	 * First from current to tail if possible.
	 * Then from the beginning of the buffer until necessary
	 */

	count = min(CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE),
		    SERIAL_XMIT_SIZE - info->xmit.tail);
	console->write(console, info->xmit.buf+info->xmit.tail, count);

	info->xmit.tail = (info->xmit.tail+count) & (SERIAL_XMIT_SIZE-1);

	/*
	 * We have more at the beginning of the buffer
	 */
	count = CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
	if (count) {
		console->write(console, info->xmit.buf, count);
		info->xmit.tail += count;
	}
out:
	local_irq_restore(flags);
}

static void rs_flush_chars(struct tty_struct *tty)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;

	if (info->xmit.head == info->xmit.tail || tty->stopped || tty->hw_stopped ||
	    !info->xmit.buf)
		return;

	transmit_chars(info, NULL);
}


static int rs_write(struct tty_struct * tty,
		    const unsigned char *buf, int count)
{
	int	c, ret = 0;
	struct async_struct *info = (struct async_struct *)tty->driver_data;
	unsigned long flags;

	if (!tty || !info->xmit.buf || !tmp_buf) return 0;

	local_irq_save(flags);
	while (1) {
		c = CIRC_SPACE_TO_END(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
		if (count < c)
			c = count;
		if (c <= 0) {
			break;
		}
		memcpy(info->xmit.buf + info->xmit.head, buf, c);
		info->xmit.head = ((info->xmit.head + c) &
				   (SERIAL_XMIT_SIZE-1));
		buf += c;
		count -= c;
		ret += c;
	}
	local_irq_restore(flags);
	/*
	 * Hey, we transmit directly from here in our case
	 */
	if (CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE)
	    && !tty->stopped && !tty->hw_stopped) {
		transmit_chars(info, NULL);
	}
	return ret;
}

static int rs_write_room(struct tty_struct *tty)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;

	return CIRC_SPACE(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
}

static int rs_chars_in_buffer(struct tty_struct *tty)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;

	return CIRC_CNT(info->xmit.head, info->xmit.tail, SERIAL_XMIT_SIZE);
}

static void rs_flush_buffer(struct tty_struct *tty)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;
	unsigned long flags;

	local_irq_save(flags);
	info->xmit.head = info->xmit.tail = 0;
	local_irq_restore(flags);

	wake_up_interruptible(&tty->write_wait);

	if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
	    tty->ldisc.write_wakeup)
		(tty->ldisc.write_wakeup)(tty);
}

/*
 * This function is used to send a high-priority XON/XOFF character to
 * the device
 */
static void rs_send_xchar(struct tty_struct *tty, char ch)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;

	info->x_char = ch;
	if (ch) {
		/*
		 * I guess we could call console->write() directly but
		 * let's do that for now.
		 */
		transmit_chars(info, NULL);
	}
}

/*
 * ------------------------------------------------------------
 * rs_throttle()
 *
 * This routine is called by the upper-layer tty layer to signal that
 * incoming characters should be throttled.
 * ------------------------------------------------------------
 */
static void rs_throttle(struct tty_struct * tty)
{
	if (I_IXOFF(tty)) rs_send_xchar(tty, STOP_CHAR(tty));

	printk(KERN_INFO "simrs_throttle called\n");
}

static void rs_unthrottle(struct tty_struct * tty)
{
	struct async_struct *info = (struct async_struct *)tty->driver_data;

	if (I_IXOFF(tty)) {
		if (info->x_char)
			info->x_char = 0;
		else
			rs_send_xchar(tty, START_CHAR(tty));
	}
	printk(KERN_INFO "simrs_unthrottle called\n");
}

/*
 * rs_break() --- routine which turns the break handling on or off
 */
static void rs_break(struct tty_struct *tty, int break_state)
{
}

static int rs_ioctl(struct tty_struct *tty, struct file * file,
		    unsigned int cmd, unsigned long arg)
{
	if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
	    (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGSTRUCT) &&
	    (cmd != TIOCMIWAIT) && (cmd != TIOCGICOUNT)) {
		if (tty->flags & (1 << TTY_IO_ERROR))
		    return -EIO;
	}

	switch (cmd) {
		case TIOCMGET:
			printk(KERN_INFO "rs_ioctl: TIOCMGET called\n");
			return -EINVAL;
		case TIOCMBIS:
		case TIOCMBIC:
		case TIOCMSET:
			printk(KERN_INFO "rs_ioctl: TIOCMBIS/BIC/SET called\n");
			return -EINVAL;
		case TIOCGSERIAL:
			printk(KERN_INFO "simrs_ioctl TIOCGSERIAL called\n");
			return 0;
		case TIOCSSERIAL:
			printk(KERN_INFO "simrs_ioctl TIOCSSERIAL called\n");
			return 0;
		case TIOCSERCONFIG:
			printk(KERN_INFO "rs_ioctl: TIOCSERCONFIG called\n");
			return -EINVAL;

		case TIOCSERGETLSR: /* Get line status register */
			printk(KERN_INFO "rs_ioctl: TIOCSERGETLSR called\n");
			return  -EINVAL;

		case TIOCSERGSTRUCT:
			printk(KERN_INFO "rs_ioctl: TIOCSERGSTRUCT called\n");
#if 0
			if (copy_to_user((struct async_struct *) arg,
					 info, sizeof(struct async_struct)))
				return -EFAULT;
#endif
			return 0;

		/*
		 * 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
		 */
		case TIOCMIWAIT:
			printk(KERN_INFO "rs_ioctl: TIOCMIWAIT: called\n");
			return 0;
		/*
		 * Get counter of input serial line interrupts (DCD,RI,DSR,CTS)
		 * Return: write counters to the user passed counter struct
		 * NB: both 1->0 and 0->1 transitions are counted except for
		 *     RI where only 0->1 is counted.
		 */
		case TIOCGICOUNT:
			printk(KERN_INFO "rs_ioctl: TIOCGICOUNT called\n");
			return 0;

		case TIOCSERGWILD:
		case TIOCSERSWILD:
			/* "setserial -W" is called in Debian boot */
			printk (KERN_INFO "TIOCSER?WILD ioctl obsolete, ignored.\n");
			return 0;

		default:
			return -ENOIOCTLCMD;
		}
	return 0;
}

#define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))

static void rs_set_termios(struct tty_struct *tty, struct ktermios *old_termios)
{
	unsigned int cflag = tty->termios->c_cflag;

	if (   (cflag == old_termios->c_cflag)
	    && (   RELEVANT_IFLAG(tty->termios->c_iflag)
		== RELEVANT_IFLAG(old_termios->c_iflag)))
	  return;


	/* Handle turning off CRTSCTS */
	if ((old_termios->c_cflag & CRTSCTS) &&
	    !(tty->termios->c_cflag & CRTSCTS)) {
		tty->hw_stopped = 0;
		rs_start(tty);
	}
}
/*
 * This routine will shutdown a serial port; interrupts are disabled, and
 * DTR is dropped if the hangup on close termio flag is on.
 */
static void shutdown(struct async_struct * info)
{
	unsigned long	flags;
	struct serial_state *state;
	int		retval;