uart.c

讲述linux的初始化过程

#endif
	return ret;
}

int rs_8xx_read_proc(char *page, char **start, off_t off, int count,
		 int *eof, void *data)
{
	int i, len = 0;
	off_t	begin = 0;

	len += sprintf(page, "serinfo:1.0 driver:%s\n", serial_version);
	for (i = 0; i < NR_PORTS && len < 4000; i++) {
		len += line_info(page + len, &rs_table[i]);
		if (len+begin > off+count)
			goto done;
		if (len+begin < off) {
			begin += len;
			len = 0;
		}
	}
	*eof = 1;
done:
	if (off >= len+begin)
		return 0;
	*start = page + (begin-off);
	return ((count < begin+len-off) ? count : begin+len-off);
}

/*
 * ---------------------------------------------------------------------
 * rs_init() and friends
 *
 * rs_init() is called at boot-time to initialize the serial driver.
 * ---------------------------------------------------------------------
 */

/*
 * This routine prints out the appropriate serial driver version
 * number, and identifies which options were configured into this
 * driver.
 */
static _INLINE_ void show_serial_version(void)
{
 	printk(KERN_INFO "%s version %s\n", serial_name, serial_version);
}


/*
 * The serial console driver used during boot.  Note that these names
 * clash with those found in "serial.c", so we currently can't support
 * the 16xxx uarts and these at the same time.  I will fix this to become
 * an indirect function call from tty_io.c (or something).
 */

#ifdef CONFIG_SERIAL_CONSOLE

/*
 * Print a string to the serial port trying not to disturb any possible
 * real use of the port...
 */
static void my_console_write(int idx, const char *s,
				unsigned count)
{
	struct		serial_state	*ser;
	ser_info_t			*info;
	unsigned			i;
	volatile	cbd_t		*bdp, *bdbase;
	volatile	smc_uart_t	*up;
	volatile	u_char		*cp;

	ser = rs_table + idx;

	/* If the port has been initialized for general use, we have
	 * to use the buffer descriptors allocated there.  Otherwise,
	 * we simply use the single buffer allocated.
	 */
	if ((info = (ser_info_t *)ser->info) != NULL) {
		bdp = info->tx_cur;
		bdbase = info->tx_bd_base;
	}
	else {
		/* Pointer to UART in parameter ram.
		*/
		up = (smc_uart_t *)&cpmp->cp_dparam[ser->port];

		/* Get the address of the host memory buffer.
		 */
		bdp = bdbase = (cbd_t *)&cpmp->cp_dpmem[up->smc_tbase];
	}

	/*
	 * We need to gracefully shut down the transmitter, disable
	 * interrupts, then send our bytes out.
	 */

	/*
	 * Now, do each character.  This is not as bad as it looks
	 * since this is a holding FIFO and not a transmitting FIFO.
	 * We could add the complexity of filling the entire transmit
	 * buffer, but we would just wait longer between accesses......
	 */
	for (i = 0; i < count; i++, s++) {
		/* Wait for transmitter fifo to empty.
		 * Ready indicates output is ready, and xmt is doing
		 * that, not that it is ready for us to send.
		 */
		while (bdp->cbd_sc & BD_SC_READY);

		/* Send the character out.
		 * If the buffer address is in the CPM DPRAM, don't
		 * convert it.
		 */
		if ((uint)(bdp->cbd_bufaddr) > (uint)IMAP_ADDR)
			cp = (u_char *)(bdp->cbd_bufaddr);
		else
			cp = __va(bdp->cbd_bufaddr);
		*cp = *s;
		
		bdp->cbd_datlen = 1;
		bdp->cbd_sc |= BD_SC_READY;

		if (bdp->cbd_sc & BD_SC_WRAP)
			bdp = bdbase;
		else
			bdp++;

		/* if a LF, also do CR... */
		if (*s == 10) {
			while (bdp->cbd_sc & BD_SC_READY);
			cp = __va(bdp->cbd_bufaddr);
			*cp = 13;
			bdp->cbd_datlen = 1;
			bdp->cbd_sc |= BD_SC_READY;

			if (bdp->cbd_sc & BD_SC_WRAP) {
				bdp = bdbase;
			}
			else {
				bdp++;
			}
		}
	}

	/*
	 * Finally, Wait for transmitter & holding register to empty
	 *  and restore the IER
	 */
	while (bdp->cbd_sc & BD_SC_READY);

	if (info)
		info->tx_cur = (cbd_t *)bdp;
}

static void serial_console_write(struct console *c, const char *s,
				unsigned count)
{
#ifdef CONFIG_KGDB
	/* Try to let stub handle output. Returns true if it did. */ 
	if (kgdb_output_string(s, count))
		return;
#endif
	my_console_write(c->index, s, count);
}

#ifdef CONFIG_XMON
int
xmon_8xx_write(const char *s, unsigned count)
{
	my_console_write(0, s, count);
	return(count);
}
#endif

#ifdef CONFIG_KGDB
void
putDebugChar(char ch)
{
	my_console_write(0, &ch, 1);
}
#endif

/*
 * Receive character from the serial port.  This only works well
 * before the port is initialized for real use.
 */
static int my_console_wait_key(int idx, int xmon, char *obuf)
{
	struct serial_state		*ser;
	u_char				c, *cp;
	ser_info_t			*info;
	volatile	cbd_t		*bdp;
	volatile	smc_uart_t	*up;
	int				i;

	ser = rs_table + idx;

	/* Pointer to UART in parameter ram.
	*/
	up = (smc_uart_t *)&cpmp->cp_dparam[ser->port];

	/* Get the address of the host memory buffer.
	 * If the port has been initialized for general use, we must
	 * use information from the port structure.
	 */
	if ((info = (ser_info_t *)ser->info))
		bdp = info->rx_cur;
	else
		bdp = (cbd_t *)&cpmp->cp_dpmem[up->smc_rbase];

	/*
	 * We need to gracefully shut down the receiver, disable
	 * interrupts, then read the input.
	 * XMON just wants a poll.  If no character, return -1, else
	 * return the character.
	 */
	if (!xmon) {
		while (bdp->cbd_sc & BD_SC_EMPTY);
	}
	else {
		if (bdp->cbd_sc & BD_SC_EMPTY)
			return -1;
	}

	/* If the buffer address is in the CPM DPRAM, don't
	 * convert it.
	 */
	if ((uint)(bdp->cbd_bufaddr) > (uint)IMAP_ADDR)
		cp = (u_char *)(bdp->cbd_bufaddr);
	else
		cp = __va(bdp->cbd_bufaddr);

	if (obuf) {
		i = c = bdp->cbd_datlen;
		while (i-- > 0)
			*obuf++ = *cp++;
	}
	else {
		c = *cp;
	}
	bdp->cbd_sc |= BD_SC_EMPTY;

	if (info) {
		if (bdp->cbd_sc & BD_SC_WRAP) {
			bdp = info->rx_bd_base;
		}
		else {
			bdp++;
		}
		info->rx_cur = (cbd_t *)bdp;
	}

	return((int)c);
}

static int serial_console_wait_key(struct console *co)
{
	return(my_console_wait_key(co->index, 0, NULL));
}

#ifdef CONFIG_XMON
int
xmon_8xx_read_poll(void)
{
	return(my_console_wait_key(0, 1, NULL));
}

int
xmon_8xx_read_char(void)
{
	return(my_console_wait_key(0, 0, NULL));
}
#endif

#ifdef CONFIG_KGDB
static char kgdb_buf[RX_BUF_SIZE], *kgdp;
static int kgdb_chars;

unsigned char
getDebugChar(void)
{
	if (kgdb_chars <= 0) {
		kgdb_chars = my_console_wait_key(0, 0, kgdb_buf);
		kgdp = kgdb_buf;
	}
	kgdb_chars--;

	return(*kgdp++);
}

void kgdb_interruptible(int state)
{
}
void kgdb_map_scc(void)
{
	struct		serial_state *ser;
	uint		mem_addr;
	volatile	cbd_t		*bdp;
	volatile	smc_uart_t	*up;

	cpmp = (cpm8xx_t *)&(((immap_t *)IMAP_ADDR)->im_cpm);

	/* To avoid data cache CPM DMA coherency problems, allocate a
	 * buffer in the CPM DPRAM.  This will work until the CPM and
	 * serial ports are initialized.  At that time a memory buffer
	 * will be allocated.
	 * The port is already initialized from the boot procedure, all
	 * we do here is give it a different buffer and make it a FIFO.
	 */

	ser = rs_table;

	/* Right now, assume we are using SMCs.
	*/
	up = (smc_uart_t *)&cpmp->cp_dparam[ser->port];

	/* Allocate space for an input FIFO, plus a few bytes for output.
	 * Allocate bytes to maintain word alignment.
	 */
	mem_addr = (uint)(&cpmp->cp_dpmem[0x1000]);

	/* Set the physical address of the host memory buffers in
	 * the buffer descriptors.
	 */
	bdp = (cbd_t *)&cpmp->cp_dpmem[up->smc_rbase];
	bdp->cbd_bufaddr = mem_addr;

	bdp = (cbd_t *)&cpmp->cp_dpmem[up->smc_tbase];
	bdp->cbd_bufaddr = mem_addr+RX_BUF_SIZE;

	up->smc_mrblr = RX_BUF_SIZE;		/* receive buffer length */
	up->smc_maxidl = RX_BUF_SIZE;
}
#endif

static kdev_t serial_console_device(struct console *c)
{
	return MKDEV(TTY_MAJOR, 64 + c->index);
}


static struct console sercons = {
	name:		"ttyS",
	write:		serial_console_write,
	device:		serial_console_device,
	wait_key:	serial_console_wait_key,
	setup:		serial_console_setup,
	flags:		CON_PRINTBUFFER,
	index:		CONFIG_SERIAL_CONSOLE_PORT,
};

/*
 *	Register console.
 */
long __init console_8xx_init(long kmem_start, long kmem_end)
{
	register_console(&sercons);
	return kmem_start;
}

#endif

/* Index in baud rate table of the default console baud rate.
*/
static	int	baud_idx;

/*
 * The serial driver boot-time initialization code!
 */
int __init rs_8xx_init(void)
{
	struct serial_state * state;
	ser_info_t	*info;
	uint		mem_addr, dp_addr, iobits;
	int		i, j, idx;
	ushort		chan;
	volatile	cbd_t		*bdp;
	volatile	cpm8xx_t	*cp;
	volatile	smc_t		*sp;
	volatile	smc_uart_t	*up;
	volatile	scc_t		*scp;
	volatile	scc_uart_t	*sup;
	volatile	immap_t		*immap;
	
	init_bh(SERIAL_BH, do_serial_bh);

	show_serial_version();

	/* Initialize the tty_driver structure */
	
	__clear_user(&serial_driver,sizeof(struct tty_driver));
	serial_driver.magic = TTY_DRIVER_MAGIC;
	serial_driver.driver_name = "serial";
	serial_driver.name = "ttyS";
	serial_driver.major = TTY_MAJOR;
	serial_driver.minor_start = 64;
	serial_driver.num = NR_PORTS;
	serial_driver.type = TTY_DRIVER_TYPE_SERIAL;
	serial_driver.subtype = SERIAL_TYPE_NORMAL;
	serial_driver.init_termios = tty_std_termios;
	serial_driver.init_termios.c_cflag =
		baud_idx | CS8 | CREAD | HUPCL | CLOCAL;
	serial_driver.flags = TTY_DRIVER_REAL_RAW;
	serial_driver.refcount = &serial_refcount;
	serial_driver.table = serial_table;
	serial_driver.termios = serial_termios;
	serial_driver.termios_locked = serial_termios_locked;

	serial_driver.open = rs_8xx_open;
	serial_driver.close = rs_8xx_close;
	serial_driver.write = rs_8xx_write;
	serial_driver.put_char = rs_8xx_put_char;
	serial_driver.write_room = rs_8xx_write_room;
	serial_driver.chars_in_buffer = rs_8xx_chars_in_buffer;
	serial_driver.flush_buffer = rs_8xx_flush_buffer;
	serial_driver.ioctl = rs_8xx_ioctl;
	serial_driver.throttle = rs_8xx_throttle;
	serial_driver.unthrottle = rs_8xx_unthrottle;
	serial_driver.send_xchar = rs_8xx_send_xchar;
	serial_driver.set_termios = rs_8xx_set_termios;
	serial_driver.stop = rs_8xx_stop;
	serial_driver.start = rs_8xx_start;
	serial_driver.hangup = rs_8xx_hangup;
	serial_driver.wait_until_sent = rs_8xx_wait_until_sent;
	serial_driver.read_proc = rs_8xx_read_proc;
	
	/*
	 * The callout device is just like normal device except for
	 * major number and the subtype code.
	 */
	callout_driver = serial_driver;
	callout_driver.name = "cua";
	callout_driver.major = TTYAUX_MAJOR;
	callout_driver.subtype = SERIAL_TYPE_CALLOUT;
	callout_driver.read_proc = 0;
	callout_driver.proc_entry = 0;

	if (tty_register_driver(&serial_driver))
		panic("Couldn't register serial driver\n");
	if (tty_register_driver(&callout_driver))
		panic("Couldn't register callout driver\n");
	
	cp = cpmp;	/* Get pointer to Communication Processor */
	immap = (immap_t *)IMAP_ADDR;	/* and to internal registers */


	/* Configure SCC2, SCC3, and SCC4 instead of port A parallel I/O.
	 */
#ifdef CONFIG_8xxSCC
#ifndef CONFIG_MBX
	/* The "standard" configuration through the 860.
	*/
	immap->im_ioport.iop_papar |= 0x00fc;
	immap->im_ioport.iop_padir &= ~0x00fc;
	immap->im_ioport.iop_paodr &= ~0x00fc;
#else
	/* On the MBX, SCC3 is through Port D.
	*/
	immap->im_ioport.iop_papar |= 0x000c;	/* SCC2 on port A */
	immap->im_ioport.iop_padir &= ~0x000c;
	immap->im_ioport.iop_paodr &= ~0x000c;

	immap->im_ioport.iop_pdpar |= 0x0030;	/* SCC3 on port D */
#endif

	/* Since we don't yet do modem control, connect the port C pins
	 * as general purpose I/O.  This will assert CTS and CD for the
	 * SCC ports.
	 */
	immap->im_ioport.iop_pcdir |= 0x03c6;
	immap->im_ioport.iop_pcpar &= ~0x03c6;

	/* Connect SCC2 and SCC3 to NMSI.  Connect BRG3 to SCC2 and
	 * BRG4 to SCC3.
	 */
	cp->cp_sicr &= ~0x00ffff00;
	cp->cp_sicr |= 0x001b1200;

#ifdef CONFIG_PP04
	/* Frequentis PP04 forced to RS-232 until we know better.
	 * Port C 12 and 13 low enables RS-232 on SCC3 and SCC4.
	 */
	immap->im_ioport.iop_pcdir |= 0x000c;
	immap->im_ioport.iop_pcpar &= ~0x000c;
	immap->im_ioport.iop_pcdat &= ~0x000c;

	/* This enables the TX driver.
	*/
	cp->cp_pbpar &= ~0x6000;
	cp->cp_pbdat &= ~0x6000;
#endif
#endif

	for (i = 0, state = rs_table; i < NR_PORTS; i++,state++) {
		state->magic = SSTATE_MAGIC;
		state->line = i;
		state->type = PORT_UNKNOWN;
		state->custom_divisor = 0;
		state->close_delay = 5*HZ/10;
		state->closing_wait = 30*HZ;
		state->callout_termios = callout_driver.init_termios;
		state->normal_termios = serial_driver.init_termios;
		state->icount.cts = state->icount.dsr = 
			state->icount.rng = state->icount.dcd = 0;
		state->icount.rx = state->icount.tx = 0;
		state->icount.frame = state->icount.parity = 0;
		state->icount.overrun = state->icount.brk = 0;
		printk(KERN_INFO "ttyS%02d at 0x%04x is a %s\n",
		       i, (unsigned int)(state->port),
		       (state->smc_scc_num & NUM_IS_SCC) ? "SCC" : "SMC");
#ifdef CONFIG_SERIAL_CONSOLE
		/* If we just printed the message on the console port, and
		 * we are about to initialize it for general use, we have
		 * to wait a couple of character times for