uart.c

讲述linux的初始化过程

/*
 *  UART driver for MPC860 CPM SCC or SMC
 *  Copyright (c) 1997 Dan Malek ([e-mail])
 *
 * I used the serial.c driver as the framework for this driver.
 * Give credit to those guys.
 * The original code was written for the MBX860 board.  I tried to make
 * it generic, but there may be some assumptions in the structures that
 * have to be fixed later.
 * To save porting time, I did not bother to change any object names
 * that are not accessed outside of this file.
 * It still needs lots of work........When it was easy, I included code
 * to support the SCCs, but this has never been tested, nor is it complete.
 * Only the SCCs support modem control, so that is not complete either.
 *
 * This module exports the following rs232 io functions:
 *
 *	int rs_8xx_init(void);
 */

#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/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/mm.h>
#include <linux/malloc.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <asm/uaccess.h>
#include <asm/8xx_immap.h>
#include <asm/mpc8xx.h>
#include "commproc.h"

#ifdef CONFIG_KGDB
extern void breakpoint(void);
extern void set_debug_traps(void);
extern int  kgdb_output_string (const char* s, unsigned int count);
#endif

#ifdef CONFIG_SERIAL_CONSOLE
#include <linux/console.h>

/* this defines the index into rs_table for the port to use
*/
#ifndef CONFIG_SERIAL_CONSOLE_PORT
#define CONFIG_SERIAL_CONSOLE_PORT	0
#endif
#endif

#if 0
/* SCC2 for console
*/
#undef CONFIG_SERIAL_CONSOLE_PORT
#define CONFIG_SERIAL_CONSOLE_PORT	2
#endif

#define TX_WAKEUP	ASYNC_SHARE_IRQ

static char *serial_name = "CPM UART driver";
static char *serial_version = "0.03";

static DECLARE_TASK_QUEUE(tq_serial);

static struct tty_driver serial_driver, callout_driver;
static int serial_refcount;
static int serial_console_setup(struct console *co, char *options);

/*
 * Serial driver configuration section.  Here are the various options:
 */
#define SERIAL_PARANOIA_CHECK
#define CONFIG_SERIAL_NOPAUSE_IO
#define SERIAL_DO_RESTART

/* Set of debugging defines */

#undef SERIAL_DEBUG_INTR
#undef SERIAL_DEBUG_OPEN
#undef SERIAL_DEBUG_FLOW
#undef SERIAL_DEBUG_RS_WAIT_UNTIL_SENT

#define _INLINE_ inline
  
#define DBG_CNT(s)

/* We overload some of the items in the data structure to meet our
 * needs.  For example, the port address is the CPM parameter ram
 * offset for the SCC or SMC.  The maximum number of ports is 4 SCCs and
 * 2 SMCs.  The "hub6" field is used to indicate the channel number, with
 * a flag indicating SCC or SMC, and the number is used as an index into
 * the CPM parameter area for this device.
 * The "type" field is currently set to 0, for PORT_UNKNOWN.  It is
 * not currently used.  I should probably use it to indicate the port
 * type of SMC or SCC.
 * The SMCs do not support any modem control signals.
 */
#define smc_scc_num	hub6
#define NUM_IS_SCC	((int)0x00010000)
#define PORT_NUM(P)	((P) & 0x0000ffff)

/* Processors other than the 860 only get SMCs configured by default.
 * Either they don't have SCCs or they are allocated somewhere else.
 * Of course, there are now 860s without some SCCs, so we will need to
 * address that someday.
 * The Embedded Planet Multimedia I/O cards use TDM interfaces to the
 * stereo codec parts, and we use SMC2 to help support that.
 */
static struct serial_state rs_table[] = {
	/* UART CLK   PORT          IRQ      FLAGS  NUM   */
	{ 0,     0, PROFF_SMC1, CPMVEC_SMC1,   0,    0 },    /* SMC1 ttyS0 */
#ifdef CONFIG_8xxSMC2
	{ 0,     0, PROFF_SMC2, CPMVEC_SMC2,   0,    1 },    /* SMC2 ttyS1 */
#endif
#ifdef CONFIG_8xxSCC
	{ 0,     0, PROFF_SCC2, CPMVEC_SCC2,   0,    (NUM_IS_SCC | 1) },    /* SCC2 ttyS2 */
	{ 0,     0, PROFF_SCC3, CPMVEC_SCC3,   0,    (NUM_IS_SCC | 2) },    /* SCC3 ttyS3 */
#endif
};

#define NR_PORTS	(sizeof(rs_table)/sizeof(struct serial_state))

static struct tty_struct *serial_table[NR_PORTS];
static struct termios *serial_termios[NR_PORTS];
static struct termios *serial_termios_locked[NR_PORTS];

/* The number of buffer descriptors and their sizes.
*/
#define RX_NUM_FIFO	4
#define RX_BUF_SIZE	32
#define TX_NUM_FIFO	4
#define TX_BUF_SIZE	32

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

/* The async_struct in serial.h does not really give us what we
 * need, so define our own here.
 */
typedef struct serial_info {
	int			magic;
	int			flags;
	struct serial_state	*state;
	struct tty_struct 	*tty;
	int			read_status_mask;
	int			ignore_status_mask;
	int			timeout;
	int			line;
	int			x_char;	/* xon/xoff character */
	int			close_delay;
	unsigned short		closing_wait;
	unsigned short		closing_wait2;
	unsigned long		event;
	unsigned long		last_active;
	int			blocked_open; /* # of blocked opens */
	long			session; /* Session of opening process */
	long			pgrp; /* pgrp of opening process */
	struct tq_struct	tqueue;
	struct tq_struct	tqueue_hangup;
	wait_queue_head_t	open_wait;
	wait_queue_head_t	close_wait;

	/* CPM Buffer Descriptor pointers.
	*/
	cbd_t			*rx_bd_base;
	cbd_t			*rx_cur;
	cbd_t			*tx_bd_base;
	cbd_t			*tx_cur;
} ser_info_t;

static void change_speed(ser_info_t *info);
static void rs_8xx_wait_until_sent(struct tty_struct *tty, int timeout);

static inline int serial_paranoia_check(ser_info_t *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 async_struct 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 and the timeouts,
 * indexed by the termio value.  The generic CPM functions are responsible
 * for setting and assigning baud rate generators for us.
 */
static int baud_table[] = {
	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
	9600, 19200, 38400, 57600, 115200, 230400, 460800, 0 };


/*
 * ------------------------------------------------------------
 * 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_8xx_stop(struct tty_struct *tty)
{
	ser_info_t *info = (ser_info_t *)tty->driver_data;
	int	idx;
	unsigned long flags;
	volatile scc_t	*sccp;
	volatile smc_t	*smcp;

	if (serial_paranoia_check(info, tty->device, "rs_stop"))
		return;
	
	save_flags(flags); cli();
	idx = PORT_NUM(info->state->smc_scc_num);
	if (info->state->smc_scc_num & NUM_IS_SCC) {
		sccp = &cpmp->cp_scc[idx];
		sccp->scc_sccm &= ~UART_SCCM_TX;
	}
	else {
		smcp = &cpmp->cp_smc[idx];
		smcp->smc_smcm &= ~SMCM_TX;
	}
	restore_flags(flags);
}

static void rs_8xx_start(struct tty_struct *tty)
{
	ser_info_t *info = (ser_info_t *)tty->driver_data;
	int	idx;
	unsigned long flags;
	volatile scc_t	*sccp;
	volatile smc_t	*smcp;

	if (serial_paranoia_check(info, tty->device, "rs_stop"))
		return;
	
	idx = PORT_NUM(info->state->smc_scc_num);
	save_flags(flags); cli();
	if (info->state->smc_scc_num & NUM_IS_SCC) {
		sccp = &cpmp->cp_scc[idx];
		sccp->scc_sccm |= UART_SCCM_TX;
	}
	else {
		smcp = &cpmp->cp_smc[idx];
		smcp->smc_smcm |= SMCM_TX;
	}
	restore_flags(flags);
}

/*
 * ----------------------------------------------------------------------
 *
 * Here starts the interrupt handling routines.  All of the following
 * subroutines are declared as inline and are folded into
 * rs_interrupt().  They were separated out for readability's sake.
 *
 * Note: rs_interrupt() is a "fast" interrupt, which means that it
 * runs with interrupts turned off.  People who may want to modify
 * rs_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 rs_sched_event(ser_info_t *info,
				  int event)
{
	info->event |= 1 << event;
	queue_task(&info->tqueue, &tq_serial);
	mark_bh(SERIAL_BH);
}

static _INLINE_ void receive_chars(ser_info_t *info)
{
	struct tty_struct *tty = info->tty;
	unsigned char ch, *cp;
	/*int	ignored = 0;*/
	int	i;
	ushort	status;
	struct	async_icount *icount;
	volatile cbd_t	*bdp;

	icount = &info->state->icount;

	/* Just loop through the closed BDs and copy the characters into
	 * the buffer.
	 */
	bdp = info->rx_cur;
	for (;;) {
		if (bdp->cbd_sc & BD_SC_EMPTY)	/* If this one is empty */
			break;			/*   we are all done */

		/* The read status mask tell us what we should do with
		 * incoming characters, especially if errors occur.
		 * One special case is the use of BD_SC_EMPTY.  If
		 * this is not set, we are supposed to be ignoring
		 * inputs.  In this case, just mark the buffer empty and
		 * continue.
		if (!(info->read_status_mask & BD_SC_EMPTY)) {
			bdp->cbd_sc |= BD_SC_EMPTY;
			bdp->cbd_sc &=
				~(BD_SC_BR | BD_SC_FR | BD_SC_PR | BD_SC_OV);

			if (bdp->cbd_sc & BD_SC_WRAP)
				bdp = info->rx_bd_base;
			else
				bdp++;
			continue;
		}
		 */

		/* Get the number of characters and the buffer pointer.
		*/
		i = bdp->cbd_datlen;
		cp = (unsigned char *)__va(bdp->cbd_bufaddr);
		status = bdp->cbd_sc;

		/* Check to see if there is room in the tty buffer for
		 * the characters in our BD buffer.  If not, we exit
		 * now, leaving the BD with the characters.  We'll pick
		 * them up again on the next receive interrupt (which could
		 * be a timeout).
		 */
		if ((tty->flip.count + i) >= TTY_FLIPBUF_SIZE)
			break;

		while (i-- > 0) {
			ch = *cp++;
			*tty->flip.char_buf_ptr = ch;
			icount->rx++;

#ifdef SERIAL_DEBUG_INTR
			printk("DR%02x:%02x...", ch, status);
#endif
			*tty->flip.flag_buf_ptr = 0;
			if (status & (BD_SC_BR | BD_SC_FR |
				       BD_SC_PR | BD_SC_OV)) {
				/*
				 * For statistics only
				 */
				if (status & BD_SC_BR)
					icount->brk++;
				else if (status & BD_SC_PR)
					icount->parity++;
				else if (status & BD_SC_FR)
					icount->frame++;
				if (status & BD_SC_OV)
					icount->overrun++;

				/*
				 * Now check to see if character should be
				 * ignored, and mask off conditions which
				 * should be ignored.
				if (status & info->ignore_status_mask) {
					if (++ignored > 100)
						break;
					continue;
				}
				 */
				status &= info->read_status_mask;
		
				if (status & (BD_SC_BR)) {
#ifdef SERIAL_DEBUG_INTR
					printk("handling break....");
#endif
					*tty->flip.flag_buf_ptr = TTY_BREAK;
					if (info->flags & ASYNC_SAK)
						do_SAK(tty);
				} else if (status & BD_SC_PR)
					*tty->flip.flag_buf_ptr = TTY_PARITY;
				else if (status & BD_SC_FR)
					*tty->flip.flag_buf_ptr = TTY_FRAME;
				if (status & BD_SC_OV) {
					/*
					 * Overrun is special, since it's
					 * reported immediately, and doesn't
					 * affect the current character
					 */
					if (tty->flip.count < TTY_FLIPBUF_SIZE) {
						tty->flip.count++;
						tty->flip.flag_buf_ptr++;
						tty->flip.char_buf_ptr++;
						*tty->flip.flag_buf_ptr =
								TTY_OVERRUN;
					}
				}
			}
			if (tty->flip.count >= TTY_FLIPBUF_SIZE)
				break;

			tty->flip.flag_buf_ptr++;
			tty->flip.char_buf_ptr++;
			tty->flip.count++;
		}

		/* This BD is ready to be used again.  Clear status.
		 * Get next BD.
		 */
		bdp->cbd_sc |= BD_SC_EMPTY;
		bdp->cbd_sc &= ~(BD_SC_BR | BD_SC_FR | BD_SC_PR | BD_SC_OV);

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

	info->rx_cur = (cbd_t *)bdp;

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

static _INLINE_ void receive_break(ser_info_t *info)
{
	struct tty_struct *tty = info->tty;

	info->state->icount.brk++;
	/* Check to see if there is room in the tty buffer for
	 * the break.  If not, we exit now, losing the break.  FIXME
	 */
	if ((tty->flip.count + 1) >= TTY_FLIPBUF_SIZE)
		return;
	*(tty->flip.flag_buf_ptr++) = TTY_BREAK;
	*(tty->flip.char_buf_ptr++) = 0;
	tty->flip.count++;

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

static _INLINE_ void transmit_chars(ser_info_t *info)
{
	
	if ((info->flags & TX_WAKEUP) ||
	    (info->tty->flags & (1 << TTY_DO_WRITE_WAKEUP))) {
		rs_sched_event(info, RS_EVENT_WRITE_WAKEUP);
	}

#ifdef SERIAL_DEBUG_INTR
	printk("THRE...");
#endif
}

#ifdef notdef
	/* I need to do this for the SCCs, so it is left as a reminder.
	*/
static _INLINE_ void check_modem_status(struct async_struct *info)
{
	int	status;
	struct	async_icount *icount;
	
	status = serial_in(info, UART_MSR);

	if (status & UART_MSR_ANY_DELTA) {
		icount = &info->state->icount;
		/* update input line counters */
		if (status & UART_MSR_TERI)
			icount->rng++;
		if (status & UART_MSR_DDSR)
			icount->dsr++;
		if (status & UART_MSR_DDCD) {
			icount->dcd++;
#ifdef CONFIG_HARD_PPS
			if ((info->flags & ASYNC_HARDPPS_CD) &&
			    (status & UART_MSR_DCD))
				hardpps();
#endif
		}
		if (status & UART_MSR_DCTS)
			icount->cts++;
		wake_up_interruptible(&info->delta_msr_wait);
	}

	if ((info->flags & ASYNC_CHECK_CD) && (status & UART_MSR_DDCD)) {
#if (defined(SERIAL_DEBUG_OPEN) || defined(SERIAL_DEBUG_INTR))
		printk("ttys%d CD now %s...", info->line,
		       (status & UART_MSR_DCD) ? "on" : "off");
#endif		
		if (status & UART_MSR_DCD)
			wake_up_interruptible(&info->open_wait);
		else if (!((info->flags & ASYNC_CALLOUT_ACTIVE) &&
			   (info->flags & ASYNC_CALLOUT_NOHUP))) {
#ifdef SERIAL_DEBUG_OPEN
			printk("scheduling hangup...");
#endif
			MOD_INC_USE_COUNT;