zs.c

自己根据lkd和情境分析

/* $Id: zs.c,v 1.1.1.1 2004/02/04 12:56:50 laputa Exp $
 * zs.c: Zilog serial port driver for the Sparc.
 *
 * Copyright (C) 1995 David S. Miller ([e-mail])
 * Copyright (C) 1996 Eddie C. Dost   ([e-mail])
 * Fixes by Pete A. Zaitcev <[e-mail]>.
 *
 * Fixed to use tty_get_baud_rate().
 *   Theodore Ts'o <[e-mail]>, 2001-Oct-12
 *
 * /proc/tty/driver/serial now exists and is readable.
 *   Alex Buell <[e-mail]>, 2001-12-23
 *
 */

#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/config.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/keyboard.h>
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/sysrq.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/oplib.h>
#include <asm/system.h>
#include <asm/uaccess.h>
#include <asm/bitops.h>
#include <asm/kdebug.h>
#include <asm/page.h>
#include <asm/pgtable.h>

#include <asm/sbus.h>
#ifdef __sparc_v9__
#include <asm/fhc.h>
#endif
#ifdef CONFIG_PCI
#include <linux/pci.h>
#endif

#include "sunserial.h"
#include "zs.h"
#include "sunkbd.h"
#include "sunmouse.h"

static int num_serial = 2; /* sun4/sun4c/sun4m - Two chips on board. */
#define NUM_SERIAL num_serial
#define NUM_CHANNELS (NUM_SERIAL * 2)

#define KEYBOARD_LINE 0x2
#define MOUSE_LINE    0x3

/* On 32-bit sparcs we need to delay after register accesses
 * to accomodate sun4 systems, but we do not need to flush writes.
 * On 64-bit sparc we only need to flush single writes to ensure
 * completion.
 */
#ifndef __sparc_v9__
#define ZSDELAY()		udelay(5)
#define ZSDELAY_LONG()		udelay(20)
#define ZS_WSYNC(channel)	do { } while(0)
#else
#define ZSDELAY()
#define ZSDELAY_LONG()
#define ZS_WSYNC(__channel) \
	sbus_readb(&((__channel)->control))
#endif

struct sun_zslayout **zs_chips;
struct sun_zschannel **zs_channels;
struct sun_zschannel *zs_mousechan;
struct sun_zschannel *zs_kbdchan;
struct sun_zschannel *zs_kgdbchan;
int *zs_nodes;

struct sun_serial *zs_soft;
struct sun_serial *zs_chain;  /* IRQ servicing chain */
int zilog_irq;

struct tty_struct *zs_ttys;

/* Console hooks... */
#ifdef CONFIG_SERIAL_CONSOLE
static struct console zs_console;
static int zs_console_init(void);

/*
 * Define this to get the zs_fair_output() functionality.
 */
#undef SERIAL_CONSOLE_FAIR_OUTPUT
#endif /* CONFIG_SERIAL_CONSOLE */

static unsigned char kgdb_regs[16] = {
	0, 0, 0,                     /* write 0, 1, 2 */
	(Rx8 | RxENAB),              /* write 3 */
	(X16CLK | SB1 | PAR_EVEN),   /* write 4 */
	(DTR | 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 */
	(BRSRC | BRENAB),            /* 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 | RxENAB),              /* 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 */
	(BRSRC | BRENAB),            /* write 14 */
	(DCDIE | CTSIE | TxUIE | BRKIE) /* write 15 */
};

#define ZS_CLOCK         4915200   /* Zilog input clock rate */

DECLARE_TASK_QUEUE(tq_serial);

static struct tty_driver serial_driver, callout_driver;
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

#define SERIAL_DO_RESTART

/* 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

int zs_init(void);
static void zs_kgdb_hook(int);

static void change_speed(struct sun_serial *info);

static struct tty_struct **serial_table;
static struct termios **serial_termios;
static struct termios **serial_termios_locked;

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

#undef ZS_LOG
#ifdef ZS_LOG
struct zs_logent {
	u8 reg, val;
	u8 write, __pad;
#define REGIRQ	0xff
#define REGDATA	0xfe
#define REGCTRL	0xfd
};
struct zs_logent zslog[32];
int zs_curlog;
#define ZSLOG(__reg, __val, __write) \
do{	int index = zs_curlog; \
	zslog[index].reg = (__reg); \
	zslog[index].val = (__val); \
	zslog[index].write = (__write); \
	zs_curlog = (index + 1) & (32 - 1); \
}while(0)
int zs_dumplog(char *buffer)
{
	int len = 0;
	int i;

	for (i = 0; i < 32; i++) {
		u8 reg, val, write;

		reg = zslog[i].reg;
		val = zslog[i].val;
		write = zslog[i].write;
		len += sprintf(buffer + len,
			       "ZSLOG[%2d]: reg %2x val %2x %s\n",
			       i, reg, val, write ? "write" : "read");
	}
	len += sprintf(buffer + len, "ZS current log index %d\n",
		       zs_curlog);
	return len;
}
#else
#define ZSLOG(x,y,z)	do { } while (0)
#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 = 0;
static DECLARE_MUTEX(tmp_buf_sem);

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

/* 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.
 */
static unsigned char read_zsreg(struct sun_zschannel *channel,
				unsigned char reg)
{
	unsigned char retval;

	sbus_writeb(reg, &channel->control);
	ZSDELAY();
	retval = sbus_readb(&channel->control);
	ZSDELAY();
	ZSLOG(reg, retval, 0);
	return retval;
}

static void write_zsreg(struct sun_zschannel *channel,
			unsigned char reg, unsigned char value)
{
	ZSLOG(reg, value, 1);
	sbus_writeb(reg, &channel->control);
	ZSDELAY();
	sbus_writeb(value, &channel->control);
	ZSDELAY();
}

static void load_zsregs(struct sun_serial *info, unsigned char *regs)
{
	struct sun_zschannel *channel = info->zs_channel;
	unsigned long flags;
	unsigned char stat;
	int i;

	for (i = 0; i < 1000; i++) {
		stat = read_zsreg(channel, R1);
		if (stat & ALL_SNT)
			break;
		udelay(100);
	}
	write_zsreg(channel, R3, 0);
	ZS_CLEARSTAT(channel);
	ZS_CLEARERR(channel);
	ZS_CLEARFIFO(channel);

	/* Load 'em up */
	save_flags(flags); cli();
	if (info->channelA)
		write_zsreg(channel, R9, CHRA);
	else
		write_zsreg(channel, R9, CHRB);
	ZSDELAY_LONG();
	write_zsreg(channel, R4, regs[R4]);
	write_zsreg(channel, R3, regs[R3] & ~RxENAB);
	write_zsreg(channel, R5, regs[R5] & ~TxENAB);
	write_zsreg(channel, R9, regs[R9] & ~MIE);
	write_zsreg(channel, R10, regs[R10]);
	write_zsreg(channel, R11, regs[R11]);
	write_zsreg(channel, R12, regs[R12]);
	write_zsreg(channel, R13, regs[R13]);
	write_zsreg(channel, R14, regs[R14] & ~BRENAB);
	write_zsreg(channel, R14, regs[R14]);
	write_zsreg(channel, R14, (regs[R14] & ~SNRZI) | BRENAB);
	write_zsreg(channel, R3, regs[R3]);
	write_zsreg(channel, R5, regs[R5]);
	write_zsreg(channel, R15, regs[R15]);
	write_zsreg(channel, R0, RES_EXT_INT);
	write_zsreg(channel, R0, ERR_RES);
	write_zsreg(channel, R1, regs[R1]);
	write_zsreg(channel, R9, regs[R9]);
	restore_flags(flags);
}

#define ZS_PUT_CHAR_MAX_DELAY	2000	/* 10 ms */

static void zs_put_char(struct sun_zschannel *channel, char ch)
{
	int loops = ZS_PUT_CHAR_MAX_DELAY;

	/* Do not change this to use ZSDELAY as this is
	 * a timed polling loop and on sparc64 ZSDELAY
	 * is a nop.  -DaveM
	 */
	do {
		u8 val = sbus_readb(&channel->control);
		ZSLOG(REGCTRL, val, 0);
		if (val & Tx_BUF_EMP)
			break;
		udelay(5);
	} while (--loops);

	sbus_writeb(ch, &channel->data);
	ZSDELAY();
	ZS_WSYNC(channel);
	ZSLOG(REGDATA, ch, 1);
}

/* Sets or clears DTR/RTS on the requested line */
static void zs_rtsdtr(struct sun_serial *ss, int set)
{
	unsigned long flags;

	save_flags(flags); cli();
	if(set) {
		ss->curregs[5] |= (RTS | DTR);
		write_zsreg(ss->zs_channel, 5, ss->curregs[5]);
	} else {
		ss->curregs[5] &= ~(RTS | DTR);
		write_zsreg(ss->zs_channel, 5, ss->curregs[5]);
	}
	restore_flags(flags);
	return;
}

static void kgdb_chaninit(struct sun_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/16);
	kgdb_regs[R12] = (brg & 255);
	kgdb_regs[R13] = ((brg >> 8) & 255);
	load_zsregs(ss, kgdb_regs);
}

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

	if (serial_paranoia_check(info, tty->device, "zs_stop"))
		return;
	
	save_flags(flags); cli();
	if (info->curregs[5] & TxENAB) {
		info->curregs[5] &= ~TxENAB;
		write_zsreg(info->zs_channel, 5, info->curregs[5]);
	}
	restore_flags(flags);
}

static void zs_start(struct tty_struct *tty)
{
	struct sun_serial *info = (struct sun_serial *) tty->driver_data;
	unsigned long flags;
	
	if (serial_paranoia_check(info, tty->device, "zs_start"))
		return;
	
	save_flags(flags); cli();
	if (info->xmit_cnt && info->xmit_buf && !(info->curregs[5] & TxENAB)) {
		info->curregs[5] |= TxENAB;
		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.
 */
void batten_down_hatches(void)
{
	if (!stop_a_enabled)
		return;
	/* 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");
	flush_user_windows();
#ifndef __sparc_v9__
	if((((unsigned long)linux_dbvec)>=DEBUG_FIRSTVADDR) &&
	   (((unsigned long)linux_dbvec)<=DEBUG_LASTVADDR))
		sp_enter_debugger();
	else
#endif
		prom_cmdline();

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

	return;
}


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

#ifndef __sparc_v9__
extern void breakpoint(void);  /* For the KGDB frame character */
#endif

static void receive_chars(struct sun_serial *info, struct pt_regs *regs)
{
	struct tty_struct *tty = info->tty;
	int do_queue_task = 0;

	while (1) {
		unsigned char ch, r1;

		r1 = read_zsreg(info->zs_channel, R1);
		if (r1 & (PAR_ERR | Rx_OVR | CRC_ERR)) {
			sbus_writeb(ERR_RES, &info->zs_channel->control);
			ZSDELAY();
			ZS_WSYNC(info->zs_channel);
			ZSLOG(REGCTRL, ERR_RES, 1);
		}

		ch = sbus_readb(&info->zs_channel->data);