sab82532.c

讲述linux的初始化过程

/* $Id: sab82532.c,v 1.54 2000/12/07 04:35:39 anton Exp $
 * sab82532.c: ASYNC Driver for the SIEMENS SAB82532 DUSCC.
 *
 * Copyright (C) 1997  Eddie C. Dost  ([e-mail])
 *
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/serial.h>
#include <linux/serialP.h>
#include <linux/serial_reg.h>
#include <linux/console.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/mm.h>
#include <linux/malloc.h>
#include <linux/init.h>
#include <linux/delay.h>

#include <asm/sab82532.h>
#include <asm/uaccess.h>
#include <asm/ebus.h>
#include <asm/irq.h>

#include "sunserial.h"

static DECLARE_TASK_QUEUE(tq_serial);

/* This is (one of many) a special gross hack to allow SU and
 * SAB serials to co-exist on the same machine. -DaveM
 */
#undef SERIAL_BH
#define SERIAL_BH	AURORA_BH

static struct tty_driver serial_driver, callout_driver;
static int sab82532_refcount;

/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS 256

#define SERIAL_PARANOIA_CHECK
#define SERIAL_DO_RESTART

/* Set of debugging defines */
#undef SERIAL_DEBUG_OPEN
#undef SERIAL_DEBUG_FLOW
#undef SERIAL_DEBUG_MODEM
#undef SERIAL_DEBUG_WAIT_UNTIL_SENT
#undef SERIAL_DEBUG_SEND_BREAK
#undef SERIAL_DEBUG_INTR
#define SERIAL_DEBUG_OVERFLOW 1

/* Trace things on serial device, useful for console debugging: */
#undef SERIAL_LOG_DEVICE

#ifdef SERIAL_LOG_DEVICE
static void dprint_init(int tty);
#endif

static void change_speed(struct sab82532 *info);
static void sab82532_wait_until_sent(struct tty_struct *tty, int timeout);

/*
 * This assumes you have a 29.4912 MHz clock for your UART.
 */
#define BASE_BAUD ( 29491200 / 16 )

static struct sab82532 *sab82532_chain = 0;
static struct tty_struct *sab82532_table[NR_PORTS];
static struct termios *sab82532_termios[NR_PORTS];
static struct termios *sab82532_termios_locked[NR_PORTS];

#ifdef MODULE
#undef CONFIG_SERIAL_CONSOLE
#endif

#ifdef CONFIG_SERIAL_CONSOLE
extern int serial_console;
static struct console sab82532_console;
static int sab82532_console_init(void);
static void batten_down_hatches(struct sab82532 *info);
#endif

#ifndef MIN
#define MIN(a,b)	((a) < (b) ? (a) : (b))
#endif

static char *sab82532_version[16] = {
	"V1.0", "V2.0", "V3.2", "V(0x03)",
	"V(0x04)", "V(0x05)", "V(0x06)", "V(0x07)",
	"V(0x08)", "V(0x09)", "V(0x0a)", "V(0x0b)",
	"V(0x0c)", "V(0x0d)", "V(0x0e)", "V(0x0f)"
};
static char serial_version[16];

/*
 * tmp_buf is used as a temporary buffer by sab82532_write.  We need to
 * lock it in case the copy_from_user blocks while swapping in a page,
 * and some other program tries to do a serial write at the same time.
 * Since the lock will only come under contention when the system is
 * swapping and available memory is low, it makes sense to share one
 * buffer across all the serial ports, since it significantly saves
 * memory if large numbers of serial ports are open.
 */
static unsigned char *tmp_buf = 0;
static DECLARE_MUTEX(tmp_buf_sem);

static inline int serial_paranoia_check(struct sab82532 *info,
					kdev_t device, const char *routine)
{
#ifdef SERIAL_PARANOIA_CHECK
	static const char *badmagic =
		"Warning: bad magic number for serial struct (%s) in %s\n";
	static const char *badinfo =
		"Warning: null sab82532 for (%s) in %s\n";

	if (!info) {
		printk(badinfo, kdevname(device), routine);
		return 1;
	}
	if (info->magic != SERIAL_MAGIC) {
		printk(badmagic, kdevname(device), routine);
		return 1;
	}
#endif
	return 0;
}

/*
 * This is used to figure out the divisor speeds.
 *
 * The formula is:    Baud = BASE_BAUD / ((N + 1) * (1 << M)),
 *
 * with               0 <= N < 64 and 0 <= M < 16
 *
 * XXX:	Speeds with M = 0 might not work properly for XTAL frequencies
 *      above 10 MHz.
 */
struct ebrg_struct {
	int	baud;
	int	n;
	int	m;
};

static struct ebrg_struct ebrg_table[] = {
	{       0,	0,	 0 },
	{      50,	35,	10 },
	{      75,	47,	 9 },
	{     110,	32,	 9 },
	{     134,	53,	 8 },
	{     150,	47,	 8 },
	{     200,	35,	 8 },
	{     300,	47,	 7 },
	{     600,	47,	 6 },
	{    1200,	47,	 5 },
	{    1800,	31,	 5 },
	{    2400,	47,	 4 },
	{    4800,	47,	 3 },
	{    9600,	47,	 2 },
	{   19200,	47,	 1 },
	{   38400,	23,	 1 },
	{   57600,	15,	 1 },
	{  115200,	 7,	 1 },
	{  230400,	 3,	 1 },
	{  460800,	 1,	 1 },
	{   76800,	11,	 1 },
	{  153600,	 5,	 1 },
	{  307200,	 3,	 1 },
	{  614400,	 3,	 0 },
	{  921600,	 0,	 1 },
};

#define NR_EBRG_VALUES	(sizeof(ebrg_table)/sizeof(struct ebrg_struct))

#define SAB82532_MAX_TEC_TIMEOUT 200000	/* 1 character time (at 50 baud) */
#define SAB82532_MAX_CEC_TIMEOUT  50000	/* 2.5 TX CLKs (at 50 baud) */

static __inline__ void sab82532_tec_wait(struct sab82532 *info)
{
	int timeout = info->tec_timeout;

	while ((readb(&info->regs->r.star) & SAB82532_STAR_TEC) && --timeout)
		udelay(1);
}

static __inline__ void sab82532_cec_wait(struct sab82532 *info)
{
	int timeout = info->cec_timeout;

	while ((readb(&info->regs->r.star) & SAB82532_STAR_CEC) && --timeout)
		udelay(1);
}

static __inline__ void sab82532_start_tx(struct sab82532 *info)
{
	unsigned long flags;
	int i;

	save_flags(flags); cli();

	if (info->xmit_cnt <= 0)
		goto out;

	if (!(readb(&info->regs->r.star) & SAB82532_STAR_XFW))
		goto out;

	info->interrupt_mask1 &= ~(SAB82532_IMR1_ALLS);
	writeb(info->interrupt_mask1, &info->regs->w.imr1);
	info->all_sent = 0;

	for (i = 0; i < info->xmit_fifo_size; i++) {
		u8 val = info->xmit_buf[info->xmit_tail++];
		writeb(val, &info->regs->w.xfifo[i]);
		info->xmit_tail &= (SERIAL_XMIT_SIZE - 1);
		info->icount.tx++;
		if (--info->xmit_cnt <= 0)
			break;
	}

	/* Issue a Transmit Frame command. */
	sab82532_cec_wait(info);
	writeb(SAB82532_CMDR_XF, &info->regs->w.cmdr);

out:
	restore_flags(flags);
}


/*
 * ------------------------------------------------------------
 * sab82532_stop() and sab82532_start()
 *
 * This routines are called before setting or resetting tty->stopped.
 * They enable or disable transmitter interrupts, as necessary.
 * ------------------------------------------------------------
 */
static void sab82532_stop(struct tty_struct *tty)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "sab82532_stop"))
		return;

	save_flags(flags); cli();
	info->interrupt_mask1 |= SAB82532_IMR1_XPR;
	writeb(info->interrupt_mask1, &info->regs->w.imr1);
	restore_flags(flags);
}

static void sab82532_start(struct tty_struct *tty)
{
	struct sab82532 *info = (struct sab82532 *)tty->driver_data;
	unsigned long flags;
	
	if (serial_paranoia_check(info, tty->device, "sab82532_start"))
		return;

	save_flags(flags); cli();
	info->interrupt_mask1 &= ~(SAB82532_IMR1_XPR);
	writeb(info->interrupt_mask1, &info->regs->w.imr1);
	sab82532_start_tx(info);
	restore_flags(flags);
}

/*
 * ----------------------------------------------------------------------
 *
 * Here starts the interrupt handling routines.  All of the following
 * subroutines are declared as inline and are folded into
 * sab82532_interrupt().  They were separated out for readability's sake.
 *
 * Note: sab82532_interrupt() is a "fast" interrupt, which means that it
 * runs with interrupts turned off.  People who may want to modify
 * sab82532_interrupt() should try to keep the interrupt handler as fast as
 * possible.  After you are done making modifications, it is not a bad
 * idea to do:
 * 
 * gcc -S -DKERNEL -Wall -Wstrict-prototypes -O6 -fomit-frame-pointer serial.c
 *
 * and look at the resulting assemble code in serial.s.
 *
 * 				- Ted Ts'o ([e-mail]), 7-Mar-93
 * -----------------------------------------------------------------------
 */

/*
 * This routine is used by the interrupt handler to schedule
 * processing in the software interrupt portion of the driver.
 */
static inline void sab82532_sched_event(struct sab82532 *info, int event)
{
	info->event |= 1 << event;
	queue_task(&info->tqueue, &tq_serial);
	mark_bh(SERIAL_BH);
}

static inline void receive_chars(struct sab82532 *info,
				 union sab82532_irq_status *stat)
{
	struct tty_struct *tty = info->tty;
	unsigned char buf[32];
	unsigned char status;
	int free_fifo = 0;
	int i, count = 0;

	/* Read number of BYTES (Character + Status) available. */
	if (stat->sreg.isr0 & SAB82532_ISR0_RPF) {
		count = info->recv_fifo_size;
		free_fifo++;
	}

	if (stat->sreg.isr0 & SAB82532_ISR0_TCD) {
		count = readb(&info->regs->r.rbcl) & (info->recv_fifo_size - 1);
		free_fifo++;
	}

	/* Issue a FIFO read command in case we where idle. */
	if (stat->sreg.isr0 & SAB82532_ISR0_TIME) {
		sab82532_cec_wait(info);
		writeb(SAB82532_CMDR_RFRD, &info->regs->w.cmdr);
		return;
	}

	if (stat->sreg.isr0 & SAB82532_ISR0_RFO) {
#ifdef SERIAL_DEBUG_OVERFLOW
		printk("sab82532: receive_chars: RFO");
#endif
		free_fifo++;
	}

	/* Read the FIFO. */
	for (i = 0; i < count; i++)
		buf[i] = readb(&info->regs->r.rfifo[i]);

	/* Issue Receive Message Complete command. */
	if (free_fifo) {
		sab82532_cec_wait(info);
		writeb(SAB82532_CMDR_RMC, &info->regs->w.cmdr);
	}

#ifdef CONFIG_SERIAL_CONSOLE
	if (info->is_console)
		wake_up(&keypress_wait);
#endif
	if (!tty)
		return;

	for (i = 0; i < count; ) {
		if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
#ifdef SERIAL_DEBUG_OVERFLOW
			printk("sab82532: receive_chars: tty overrun\n");
#endif
			info->icount.buf_overrun++;
			break;
		}

		tty->flip.count++;
		*tty->flip.char_buf_ptr++ = buf[i++];
		status = buf[i++];
		info->icount.rx++;

#ifdef SERIAL_DEBUG_INTR
                printk("DR%02x:%02x...", (unsigned char)*(tty->flip.char_buf_ptr - 1), status);
#endif

		if (status & SAB82532_RSTAT_PE) {
			*tty->flip.flag_buf_ptr++ = TTY_PARITY;
			info->icount.parity++;
		} else if (status & SAB82532_RSTAT_FE) {
			*tty->flip.flag_buf_ptr++ = TTY_FRAME;
			info->icount.frame++;
		}
		else
			*tty->flip.flag_buf_ptr++ = TTY_NORMAL;
	}

	queue_task(&tty->flip.tqueue, &tq_timer);
}

static inline void transmit_chars(struct sab82532 *info,
				  union sab82532_irq_status *stat)
{
	int i;

	if (stat->sreg.isr1 & SAB82532_ISR1_ALLS) {
		info->interrupt_mask1 |= SAB82532_IMR1_ALLS;
		writeb(info->interrupt_mask1, &info->regs->w.imr1);
		info->all_sent = 1;
	}

	if (!(stat->sreg.isr1 & SAB82532_ISR1_XPR))
		return;

	if (!info->tty) {
		info->interrupt_mask1 |= SAB82532_IMR1_XPR;
		writeb(info->interrupt_mask1, &info->regs->w.imr1);
		return;
	}

	if ((info->xmit_cnt <= 0) || info->tty->stopped ||
	    info->tty->hw_stopped) {
		info->interrupt_mask1 |= SAB82532_IMR1_XPR;
		writeb(info->interrupt_mask1, &info->regs->w.imr1);
		return;
	}

	info->interrupt_mask1 &= ~(SAB82532_IMR1_ALLS);
	writeb(info->interrupt_mask1, &info->regs->w.imr1);
	info->all_sent = 0;

	/* Stuff 32 bytes into Transmit FIFO. */
	for (i = 0; i < info->xmit_fifo_size; i++) {
		u8 val = info->xmit_buf[info->xmit_tail++];
		writeb(val, &info->regs->w.xfifo[i]);
		info->xmit_tail &= (SERIAL_XMIT_SIZE - 1);
		info->icount.tx++;
		if (--info->xmit_cnt <= 0)
			break;
	}

	/* Issue a Transmit Frame command. */
	sab82532_cec_wait(info);
	writeb(SAB82532_CMDR_XF, &info->regs->w.cmdr);

	if (info->xmit_cnt < WAKEUP_CHARS)
		sab82532_sched_event(info, RS_EVENT_WRITE_WAKEUP);

#ifdef SERIAL_DEBUG_INTR
	printk("THRE...");
#endif
	if (info->xmit_cnt <= 0) {
		info->interrupt_mask1 |= SAB82532_IMR1_XPR;
		writeb(info->interrupt_mask1, &info->regs->w.imr1);
	}
}

static inline void check_status(struct sab82532 *info,
				union sab82532_irq_status *stat)
{
	struct tty_struct *tty = info->tty;
	int modem_change = 0;

	if (stat->sreg.isr1 & SAB82532_ISR1_BRK) {
#ifdef CONFIG_SERIAL_CONSOLE
		if (info->is_console) {
			batten_down_hatches(info);
			return;
		}
#endif
		if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
			info->icount.buf_overrun++;
			goto check_modem;
		}
		tty->flip.count++;
		*tty->flip.flag_buf_ptr++ = TTY_PARITY;
		*tty->flip.char_buf_ptr++ = 0;
		info->icount.brk++;
	}

	if (!tty)
		return;

	if (stat->sreg.isr0 & SAB82532_ISR0_RFO) {
		if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
			info->icount.buf_overrun++;
			goto check_modem;
		}
		tty->flip.count++;
		*tty->flip.flag_buf_ptr++ = TTY_PARITY;
		*tty->flip.char_buf_ptr++ = 0;
		info->icount.overrun++;
	}

check_modem:
	if (stat->sreg.isr0 & SAB82532_ISR0_CDSC) {
		info->dcd = (readb(&info->regs->r.vstr) & SAB82532_VSTR_CD) ? 0 : 1;
		info->icount.dcd++;
		modem_change++;
#ifdef SERIAL_DEBUG_MODEM
		printk("DCD change: %d\n", info->icount.dcd);