sgiserial.c

这个linux源代码是很全面的~基本完整了~使用c编译的~由于时间问题我没有亲自测试~但就算用来做参考资料也是非常好的

/* sgiserial.c: Serial port driver for SGI machines.
 *
 * Copyright (C) 1996 David S. Miller ([e-mail])
 */

/*
 * Note: This driver seems to have been derived from some
 * version of the sbus/char/zs.c driver.  A lot of clean-up
 * and bug fixes seem to have happened to the Sun driver in
 * the intervening time.  As of 21.09.1999, I have merged in
 * ONLY the changes necessary to fix observed functional
 * problems on the Indy.  Someone really ought to do a
 * thorough pass to merge in the rest of the updates.
 * Better still, someone really ought to make it a common
 * code module for both platforms.   [e-mail]
 *
 * 20010616 - Klaus Naumann <[e-mail]> : Make serial console work with
 *                                             any speed - not only 9600
 */

#include <linux/config.h> /* for CONFIG_REMOTE_DEBUG */
#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/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/delay.h>
#include <linux/console.h>
#include <linux/init.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/sgialib.h>
#include <asm/system.h>
#include <asm/bitops.h>
#include <asm/sgi/sgihpc.h>
#include <asm/sgi/sgint23.h>
#include <asm/uaccess.h>

#include "sgiserial.h"

#define NUM_SERIAL 1     /* One chip on board. */
#define NUM_CHANNELS (NUM_SERIAL * 2)

struct sgi_zslayout *zs_chips[NUM_SERIAL] = { 0, };
struct sgi_zschannel *zs_channels[NUM_CHANNELS] = { 0, 0, };
struct sgi_zschannel *zs_conschan;
struct sgi_zschannel *zs_kgdbchan;

struct sgi_serial zs_soft[NUM_CHANNELS];
struct sgi_serial *zs_chain;  /* IRQ servicing chain */
static int zilog_irq = SGI_SERIAL_IRQ;

/* Console hooks... */
static int zs_cons_chanout;
static int zs_cons_chanin;
struct sgi_serial *zs_consinfo;

static unsigned char kgdb_regs[16] = {
	0, 0, 0,                     /* write 0, 1, 2 */
	(Rx8 | RxENABLE),            /* write 3 */
	(X16CLK | SB1 | PAR_EVEN),   /* write 4 */
	(Tx8 | TxENAB),              /* write 5 */
	0, 0, 0,                     /* write 6, 7, 8 */
	(NV),                        /* write 9 */
	(NRZ),                       /* write 10 */
	(TCBR | RCBR),               /* write 11 */
	0, 0,                        /* BRG time constant, write 12 + 13 */
	(BRENABL),                   /* write 14 */
	(DCDIE)                      /* write 15 */
};

static unsigned char zscons_regs[16] = {
	0,                           /* write 0 */
	(EXT_INT_ENAB | INT_ALL_Rx), /* write 1 */
	0,                           /* write 2 */
	(Rx8 | RxENABLE),            /* write 3 */
	(X16CLK),                    /* write 4 */
	(DTR | Tx8 | TxENAB),        /* write 5 */
	0, 0, 0,                     /* write 6, 7, 8 */
	(NV | MIE),                  /* write 9 */
	(NRZ),                       /* write 10 */
	(TCBR | RCBR),               /* write 11 */
	0, 0,                        /* BRG time constant, write 12 + 13 */
	(BRENABL),                   /* write 14 */
	(DCDIE | CTSIE | TxUIE | BRKIE) /* write 15 */
};

#define ZS_CLOCK         3672000   /* Zilog input clock rate */

DECLARE_TASK_QUEUE(tq_serial);

struct tty_driver serial_driver, callout_driver;
struct console *sgisercon;
static int serial_refcount;

/* serial subtype definitions */
#define SERIAL_TYPE_NORMAL	1
#define SERIAL_TYPE_CALLOUT	2

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

/* Debugging... DEBUG_INTR is bad to use when one of the zs
 * lines is your console ;(
 */
#undef SERIAL_DEBUG_INTR
#undef SERIAL_DEBUG_OPEN
#undef SERIAL_DEBUG_FLOW

#define RS_STROBE_TIME 10
#define RS_ISR_PASS_LIMIT 256

#define _INLINE_ inline

static void change_speed(struct sgi_serial *info);

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

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

/*
 * tmp_buf is used as a temporary buffer by serial_write.  We need to
 * lock it in case the memcpy_fromfs 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[4096]; /* This is cheating */
static DECLARE_MUTEX(tmp_buf_sem);

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

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

/*
 * This is used to figure out the divisor speeds and the timeouts
 */
static int baud_table[] = {
	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
	9600, 19200, 38400, 57600, 115200, 0 };

/*
 * Reading and writing Zilog8530 registers.  The delays are to make this
 * driver work on the Sun4 which needs a settling delay after each chip
 * register access, other machines handle this in hardware via auxiliary
 * flip-flops which implement the settle time we do in software.
 *
 * read_zsreg() and write_zsreg() may get called from rs_kgdb_hook() before
 * interrupts are enabled. Therefore we have to check ioc_iocontrol before we
 * access it.
 */
static inline unsigned char read_zsreg(struct sgi_zschannel *channel,
                                       unsigned char reg)
{
	unsigned char retval;
	volatile unsigned char junk;

	udelay(2);
	channel->control = reg;
	if (ioc_icontrol)
		junk = ioc_icontrol->istat0;
	udelay(1);
	retval = channel->control;
	return retval;
}

static inline void write_zsreg(struct sgi_zschannel *channel,
                               unsigned char reg, unsigned char value)
{
	volatile unsigned char junk;

	udelay(2);
	channel->control = reg;
	if (ioc_icontrol)
		junk = ioc_icontrol->istat0;
	udelay(1);
	channel->control = value;
	if (ioc_icontrol)
		junk = ioc_icontrol->istat0;
	return;
}

static inline void load_zsregs(struct sgi_zschannel *channel, unsigned char *regs)
{
	ZS_CLEARERR(channel);
	ZS_CLEARFIFO(channel);
	/* Load 'em up */
	write_zsreg(channel, R4, regs[R4]);
	write_zsreg(channel, R10, regs[R10]);
	write_zsreg(channel, R3, regs[R3] & ~RxENABLE);
	write_zsreg(channel, R5, regs[R5] & ~TxENAB);
	write_zsreg(channel, R1, regs[R1]);
	write_zsreg(channel, R9, regs[R9]);
	write_zsreg(channel, R11, regs[R11]);
	write_zsreg(channel, R12, regs[R12]);
	write_zsreg(channel, R13, regs[R13]);
	write_zsreg(channel, R14, regs[R14]);
	write_zsreg(channel, R15, regs[R15]);
	write_zsreg(channel, R3, regs[R3]);
	write_zsreg(channel, R5, regs[R5]);
	return;
}

/* Sets or clears DTR/RTS on the requested line */
static inline void zs_rtsdtr(struct sgi_serial *ss, int set)
{
	if(set) {
		ss->curregs[5] |= (RTS | DTR);
		ss->pendregs[5] = ss->curregs[5];
		write_zsreg(ss->zs_channel, 5, ss->curregs[5]);
	} else {
		ss->curregs[5] &= ~(RTS | DTR);
		ss->pendregs[5] = ss->curregs[5];
		write_zsreg(ss->zs_channel, 5, ss->curregs[5]);
	}
	return;
}

static inline void kgdb_chaninit(struct sgi_serial *ss, int intson, int bps)
{
	int brg;

	if(intson) {
		kgdb_regs[R1] = INT_ALL_Rx;
		kgdb_regs[R9] |= MIE;
	} else {
		kgdb_regs[R1] = 0;
		kgdb_regs[R9] &= ~MIE;
	}
	brg = BPS_TO_BRG(bps, ZS_CLOCK/ss->clk_divisor);
	kgdb_regs[R12] = (brg & 255);
	kgdb_regs[R13] = ((brg >> 8) & 255);
	load_zsregs(ss->zs_channel, kgdb_regs);
}

/* Utility routines for the Zilog */
static inline int get_zsbaud(struct sgi_serial *ss)
{
	struct sgi_zschannel *channel = ss->zs_channel;
	int brg;

	/* The baud rate is split up between two 8-bit registers in
	 * what is termed 'BRG time constant' format in my docs for
	 * the chip, it is a function of the clk rate the chip is
	 * receiving which happens to be constant.
	 */
	brg = ((read_zsreg(channel, 13)&0xff) << 8);
	brg |= (read_zsreg(channel, 12)&0xff);
	return BRG_TO_BPS(brg, (ZS_CLOCK/(ss->clk_divisor)));
}

/*
 * ------------------------------------------------------------
 * 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)
{
	struct sgi_serial *info = (struct sgi_serial *)tty->driver_data;
	unsigned long flags;

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

	save_flags(flags); cli();
	if (info->curregs[5] & TxENAB) {
		info->curregs[5] &= ~TxENAB;
		info->pendregs[5] &= ~TxENAB;
		write_zsreg(info->zs_channel, 5, info->curregs[5]);
	}
	restore_flags(flags);
}

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

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

	save_flags(flags); cli();
	if (info->xmit_cnt && info->xmit_buf && !(info->curregs[5] & TxENAB)) {
		info->curregs[5] |= TxENAB;
		info->pendregs[5] = info->curregs[5];
		write_zsreg(info->zs_channel, 5, info->curregs[5]);
	}
	restore_flags(flags);
}

/* Drop into either the boot monitor or kadb upon receiving a break
 * from keyboard/console input.
 */
static void batten_down_hatches(void)
{
	ArcEnterInteractiveMode();
#if 0
	/* If we are doing kadb, we call the debugger
	 * else we just drop into the boot monitor.
	 * Note that we must flush the user windows
	 * first before giving up control.
	 */
	printk("\n");
	if((((unsigned long)linux_dbvec)>=DEBUG_FIRSTVADDR) &&
	   (((unsigned long)linux_dbvec)<=DEBUG_LASTVADDR))
		sp_enter_debugger();
	else
		prom_halt();

	/* XXX We want to notify the keyboard driver that all
	 * XXX keys are in the up state or else weird things
	 * XXX happen...
	 */
#endif
	return;
}

/* On receive, this clears errors and the receiver interrupts */
static inline void rs_recv_clear(struct sgi_zschannel *zsc)
{
	volatile unsigned char junk;

	udelay(2);
	zsc->control = ERR_RES;
	junk = ioc_icontrol->istat0;
	udelay(2);
	zsc->control = RES_H_IUS;
	junk = ioc_icontrol->istat0;
}

/*
 * ----------------------------------------------------------------------
 *
 * 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(struct sgi_serial *info,
				    int event)
{
	info->event |= 1 << event;
	queue_task(&info->tqueue, &tq_serial);
	mark_bh(SERIAL_BH);
}

#ifdef CONFIG_REMOTE_DEBUG
extern void set_async_breakpoint(unsigned int epc);
#endif

static _INLINE_ void receive_chars(struct sgi_serial *info, struct pt_regs *regs)
{
	struct tty_struct *tty = info->tty;
	volatile unsigned char junk;
	unsigned char ch, stat;

	udelay(2);
	ch = info->zs_channel->data;
	junk = ioc_icontrol->istat0;
	udelay(2);
	stat = read_zsreg(info->zs_channel, R1);

	/* If this is the console keyboard, we need to handle
	 * L1-A's here.
	 */
	if(info->is_cons) {
		if(ch==0) { /* whee, break received */
			batten_down_hatches();
			rs_recv_clear(info->zs_channel);
			return;
		} else if (ch == 1) {
			show_state();
			return;
		} else if (ch == 2) {
			show_buffers();
			return;
		}
	}
	/* Look for kgdb 'stop' character, consult the gdb documentation
	 * for remote target debugging and arch/sparc/kernel/sparc-stub.c
	 * to see how all this works.
	 */
#ifdef CONFIG_REMOTE_DEBUG
	if((info->kgdb_channel) && (ch =='\003')) {
		set_async_breakpoint(read_32bit_cp0_register(CP0_EPC));
		goto clear_and_exit;
	}
#endif
	if(!tty)
		goto clear_and_exit;

	if (tty->flip.count >= TTY_FLIPBUF_SIZE)
		queue_task(&tty->flip.tqueue, &tq_timer);
	tty->flip.count++;
	if(stat & PAR_ERR)
		*tty->flip.flag_buf_ptr++ = TTY_PARITY;
	else if(stat & Rx_OVR)
		*tty->flip.flag_buf_ptr++ = TTY_OVERRUN;
	else if(stat & CRC_ERR)
		*tty->flip.flag_buf_ptr++ = TTY_FRAME;
	else
		*tty->flip.flag_buf_ptr++ = 0; /* XXX */
	*tty->flip.char_buf_ptr++ = ch;

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

clear_and_exit:
	rs_recv_clear(info->zs_channel);
	return;
}

static _INLINE_ void transmit_chars(struct sgi_serial *info)
{
	volatile unsigned char junk;

	/* P3: In theory we have to test readiness here because a
	 * serial console can clog the chip through zs_cons_put_char().
	 * David did not do this. I think he relies on 3-chars FIFO in 8530.
	 * Let's watch for lost _output_ characters. XXX
	 */

	/* SGI ADDENDUM: On most SGI machines, the Zilog does possess
	 *               a 16 or 17 byte fifo, so no worries. -dm
	 */

	if (info->x_char) {
		/* Send next char */
		udelay(2);
		info->zs_channel->data = info->x_char;
		junk = ioc_icontrol->istat0;

		info->x_char = 0;
		goto clear_and_return;
	}

	if((info->xmit_cnt <= 0) || info->tty->stopped) {
		/* That's peculiar... */
		udelay(2);
		info->zs_channel->control = RES_Tx_P;
		junk = ioc_icontrol->istat0;
		goto clear_and_return;
	}

	/* Send char */
	udelay(2);
	info->zs_channel->data = info->xmit_buf[info->xmit_tail++];
	junk = ioc_icontrol->istat0;

	info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
	info->xmit_cnt--;

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

	if(info->xmit_cnt <= 0) {
		udelay(2);
		info->zs_channel->control = RES_Tx_P;
		junk = ioc_icontrol->istat0;
		goto clear_and_return;
	}

clear_and_return:
	/* Clear interrupt */
	udelay(2);
	info->zs_channel->control = RES_H_IUS;
	junk = ioc_icontrol->istat0;
	return;
}

static _INLINE_ void status_handle(struct sgi_serial *info)
{
	volatile unsigned char junk;
	unsigned char status;

	/* Get status from Read Register 0 */
	udelay(2);
	status = info->zs_channel->control;
	junk = ioc_icontrol->istat0;
	/* Clear status condition... */
	udelay(2);
	info->zs_channel->control = RES_EXT_INT;
	junk = ioc_icontrol->istat0;
	/* Clear the interrupt */
	udelay(2);
	info->zs_channel->control = RES_H_IUS;
	junk = ioc_icontrol->istat0;

#if 0
	if(status & DCD) {
		if((info->tty->termios->c_cflag & CRTSCTS) &&
		   ((info->curregs[3] & AUTO_ENAB)==0)) {
			info->curregs[3] |= AUTO_ENAB;
			info->pendregs[3] |= AUTO_ENAB;
			write_zsreg(info->zs_channel, 3, info->curregs[3]);
		}
	} else {
		if((info->curregs[3] & AUTO_ENAB)) {
			info->curregs[3] &= ~AUTO_ENAB;
			info->pendregs[3] &= ~AUTO_ENAB;
			write_zsreg(info->zs_channel, 3, info->curregs[3]);
		}
	}
#endif
	/* Whee, if this is console input and this is a
	 * 'break asserted' status change interrupt, call
	 * the boot prom.
	 */
	if((status & BRK_ABRT) && info->break_abort)
		batten_down_hatches();

	/* XXX Whee, put in a buffer somewhere, the status information
	 * XXX whee whee whee... Where does the information go...
	 */
	return;
}

/*
 * This is the serial driver's generic interrupt routine
 */
void rs_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{