uart.c

讲述linux的初始化过程

#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
				printk("CTS tx start...");
#endif
				info->tty->hw_stopped = 0;
				info->IER |= UART_IER_THRI;
				serial_out(info, UART_IER, info->IER);
				rs_sched_event(info, RS_EVENT_WRITE_WAKEUP);
				return;
			}
		} else {
			if (!(status & UART_MSR_CTS)) {
#if (defined(SERIAL_DEBUG_INTR) || defined(SERIAL_DEBUG_FLOW))
				printk("CTS tx stop...");
#endif
				info->tty->hw_stopped = 1;
				info->IER &= ~UART_IER_THRI;
				serial_out(info, UART_IER, info->IER);
			}
		}
	}
}
#endif

/*
 * This is the serial driver's interrupt routine for a single port
 */
static void rs_8xx_interrupt(int irq, void * dev_id, struct pt_regs * regs)
{
	u_char	events;
	int	idx;
	ser_info_t *info;
	volatile smc_t	*smcp;
	volatile scc_t	*sccp;
	
	info = (ser_info_t *)dev_id;

	if ((idx = info->state->smc_scc_num) < SCC_NUM_BASE) {
		smcp = &immr->im_smc[idx];
		events = smcp->smc_smce;
		if (events & SMCM_RX)
			receive_chars(info);
		if (events & SMCM_TX)
			transmit_chars(info);
		smcp->smc_smce = events;
	}
	else {
		sccp = &immr->im_scc[idx - SCC_IDX_BASE];
		events = sccp->scc_scce;
		if (events & SCCM_RX)
			receive_chars(info);
		if (events & SCCM_TX)
			transmit_chars(info);
		sccp->scc_scce = events;
	}
	
#ifdef SERIAL_DEBUG_INTR
	printk("rs_interrupt_single(%d, %x)...",
					info->state->smc_scc_num, events);
#endif
#ifdef modem_control
	check_modem_status(info);
#endif
	info->last_active = jiffies;
#ifdef SERIAL_DEBUG_INTR
	printk("end.\n");
#endif
}


/*
 * -------------------------------------------------------------------
 * Here ends the serial interrupt routines.
 * -------------------------------------------------------------------
 */

/*
 * This routine is used to handle the "bottom half" processing for the
 * serial driver, known also the "software interrupt" processing.
 * This processing is done at the kernel interrupt level, after the
 * rs_interrupt() has returned, BUT WITH INTERRUPTS TURNED ON.  This
 * is where time-consuming activities which can not be done in the
 * interrupt driver proper are done; the interrupt driver schedules
 * them using rs_sched_event(), and they get done here.
 */
static void do_serial_bh(void)
{
	run_task_queue(&tq_serial);
}

static void do_softint(void *private_)
{
	ser_info_t	*info = (ser_info_t *) private_;
	struct tty_struct	*tty;
	
	tty = info->tty;
	if (!tty)
		return;

	if (test_and_clear_bit(RS_EVENT_WRITE_WAKEUP, &info->event)) {
		if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
		    tty->ldisc.write_wakeup)
			(tty->ldisc.write_wakeup)(tty);
		wake_up_interruptible(&tty->write_wait);
	}
}

/*
 * This routine is called from the scheduler tqueue when the interrupt
 * routine has signalled that a hangup has occurred.  The path of
 * hangup processing is:
 *
 * 	serial interrupt routine -> (scheduler tqueue) ->
 * 	do_serial_hangup() -> tty->hangup() -> rs_hangup()
 * 
 */
static void do_serial_hangup(void *private_)
{
	struct async_struct	*info = (struct async_struct *) private_;
	struct tty_struct	*tty;
	
	tty = info->tty;
	if (tty)
		tty_hangup(tty);
	MOD_DEC_USE_COUNT;
}

/*static void rs_8xx_timer(void)
{
	printk("rs_8xx_timer\n");
}*/


static int startup(ser_info_t *info)
{
	unsigned long flags;
	int	retval=0;
	int	idx;
	struct serial_state *state= info->state;
	volatile smc_t		*smcp;
	volatile scc_t		*sccp;
	volatile smc_uart_t	*up;
	volatile scc_uart_t	*scup;


	save_flags(flags); cli();

	if (info->flags & ASYNC_INITIALIZED) {
		goto errout;
	}

#ifdef maybe
	if (!state->port || !state->type) {
		if (info->tty)
			set_bit(TTY_IO_ERROR, &info->tty->flags);
		goto errout;
	}
#endif

#ifdef SERIAL_DEBUG_OPEN
	printk("starting up ttys%d (irq %d)...", info->line, state->irq);
#endif


#ifdef modem_control
	info->MCR = 0;
	if (info->tty->termios->c_cflag & CBAUD)
		info->MCR = UART_MCR_DTR | UART_MCR_RTS;
#endif
	
	if (info->tty)
		clear_bit(TTY_IO_ERROR, &info->tty->flags);

	/*
	 * and set the speed of the serial port
	 */
	change_speed(info);
	
	if ((idx = info->state->smc_scc_num) < SCC_NUM_BASE) {
		smcp = &immr->im_smc[idx];

		/* Enable interrupts and I/O.
		*/
		smcp->smc_smcm |= (SMCM_RX | SMCM_TX);
		smcp->smc_smcmr |= (SMCMR_REN | SMCMR_TEN);

		/* We can tune the buffer length and idle characters
		 * to take advantage of the entire incoming buffer size.
		 * If mrblr is something other than 1, maxidl has to be
		 * non-zero or we never get an interrupt.  The maxidl
		 * is the number of character times we wait after reception
		 * of the last character before we decide no more characters
		 * are coming.
		 */
		up = (smc_uart_t *)&immr->im_dprambase[state->port];
#if 0
		up->smc_mrblr = 1;	/* receive buffer length */
		up->smc_maxidl = 0;	/* wait forever for next char */
#else
		up->smc_mrblr = RX_BUF_SIZE;
		up->smc_maxidl = RX_BUF_SIZE;
#endif
		up->smc_brkcr = 1;	/* number of break chars */
	}
	else {
		sccp = &immr->im_scc[idx - SCC_IDX_BASE];
		scup = (scc_uart_t *)&immr->im_dprambase[state->port];
#if 0
		scup->scc_genscc.scc_mrblr = 1;	/* receive buffer length */
		scup->scc_maxidl = 0;	/* wait forever for next char */
#else
		scup->scc_genscc.scc_mrblr = RX_BUF_SIZE;
		scup->scc_maxidl = RX_BUF_SIZE;
#endif

		sccp->scc_sccm |= (UART_SCCM_TX | UART_SCCM_RX);
		sccp->scc_gsmrl |= (SCC_GSMRL_ENR | SCC_GSMRL_ENT);
	}

	info->flags |= ASYNC_INITIALIZED;
	restore_flags(flags);
	return 0;
	
errout:
	restore_flags(flags);
	return retval;
}

/*
 * This routine will shutdown a serial port; interrupts are disabled, and
 * DTR is dropped if the hangup on close termio flag is on.
 */
static void shutdown(ser_info_t * info)
{
	unsigned long	flags;
	struct serial_state *state;
	int		idx;
	volatile smc_t	*smcp;
	volatile scc_t	*sccp;

	if (!(info->flags & ASYNC_INITIALIZED))
		return;

	state = info->state;

#ifdef SERIAL_DEBUG_OPEN
	printk("Shutting down serial port %d (irq %d)....", info->line,
	       state->irq);
#endif
	
	save_flags(flags); cli(); /* Disable interrupts */

	if ((idx = info->state->smc_scc_num) < SCC_NUM_BASE) {
		smcp = &immr->im_smc[idx];

		/* Disable interrupts and I/O.
		*/
		smcp->smc_smcm &= ~(SMCM_RX | SMCM_TX);
#ifdef CONFIG_SERIAL_CONSOLE
		/* We can't disable the transmitter if this is the
		 * system console.
		 */
		if (idx != CONFIG_SERIAL_CONSOLE_PORT)
#endif
			smcp->smc_smcmr &= ~(SMCMR_REN | SMCMR_TEN);
	}
	else {
		sccp = &immr->im_scc[idx - SCC_IDX_BASE];
		sccp->scc_sccm &= ~(UART_SCCM_TX | UART_SCCM_RX);
		sccp->scc_gsmrl &= ~(SCC_GSMRL_ENR | SCC_GSMRL_ENT);
	}
	
	if (info->tty)
		set_bit(TTY_IO_ERROR, &info->tty->flags);

	info->flags &= ~ASYNC_INITIALIZED;
	restore_flags(flags);
}

/*
 * This routine is called to set the UART divisor registers to match
 * the specified baud rate for a serial port.
 */
static void change_speed(ser_info_t *info)
{
	int	baud_rate;
	unsigned cflag, cval, scval, prev_mode;
	int	i, bits, sbits, idx;
	unsigned long	flags;
	volatile smc_t	*smcp;
	volatile scc_t	*sccp;

	if (!info->tty || !info->tty->termios)
		return;
	cflag = info->tty->termios->c_cflag;

	/* Character length programmed into the mode register is the
	 * sum of: 1 start bit, number of data bits, 0 or 1 parity bit,
	 * 1 or 2 stop bits, minus 1.
	 * The value 'bits' counts this for us.
	 */
	cval = 0;
	scval = 0;

	/* byte size and parity */
	switch (cflag & CSIZE) {
	      case CS5: bits = 5; break;
	      case CS6: bits = 6; break;
	      case CS7: bits = 7; break;
	      case CS8: bits = 8; break;
	      /* Never happens, but GCC is too dumb to figure it out */
	      default:  bits = 8; break;
	}
	sbits = bits - 5;

	if (cflag & CSTOPB) {
		cval |= SMCMR_SL;	/* Two stops */
		scval |= SCU_PMSR_SL;
		bits++;
	}
	if (cflag & PARENB) {
		cval |= SMCMR_PEN;
		scval |= SCU_PMSR_PEN;
		bits++;
	}
	if (!(cflag & PARODD)) {
		cval |= SMCMR_PM_EVEN;
		scval |= (SCU_PMSR_REVP | SCU_PMSR_TEVP);
	}

	/* Determine divisor based on baud rate */
	i = cflag & CBAUD;
	if (i >= (sizeof(baud_table)/sizeof(int)))
		baud_rate = 9600;
	else
		baud_rate = baud_table[i];

	info->timeout = (TX_BUF_SIZE*HZ*bits);
	info->timeout += HZ/50;		/* Add .02 seconds of slop */

#ifdef modem_control
	/* CTS flow control flag and modem status interrupts */
	info->IER &= ~UART_IER_MSI;
	if (info->flags & ASYNC_HARDPPS_CD)
		info->IER |= UART_IER_MSI;
	if (cflag & CRTSCTS) {
		info->flags |= ASYNC_CTS_FLOW;
		info->IER |= UART_IER_MSI;
	} else
		info->flags &= ~ASYNC_CTS_FLOW;
	if (cflag & CLOCAL)
		info->flags &= ~ASYNC_CHECK_CD;
	else {
		info->flags |= ASYNC_CHECK_CD;
		info->IER |= UART_IER_MSI;
	}
	serial_out(info, UART_IER, info->IER);
#endif

	/*
	 * Set up parity check flag
	 */
#define RELEVANT_IFLAG(iflag) (iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))

	info->read_status_mask = (BD_SC_EMPTY | BD_SC_OV);
	if (I_INPCK(info->tty))
		info->read_status_mask |= BD_SC_FR | BD_SC_PR;
	if (I_BRKINT(info->tty) || I_PARMRK(info->tty))
		info->read_status_mask |= BD_SC_BR;
	
	/*
	 * Characters to ignore
	 */
	info->ignore_status_mask = 0;
	if (I_IGNPAR(info->tty))
		info->ignore_status_mask |= BD_SC_PR | BD_SC_FR;
	if (I_IGNBRK(info->tty)) {
		info->ignore_status_mask |= BD_SC_BR;
		/*
		 * If we're ignore parity and break indicators, ignore 
		 * overruns too.  (For real raw support).
		 */
		if (I_IGNPAR(info->tty))
			info->ignore_status_mask |= BD_SC_OV;
	}
	/*
	 * !!! ignore all characters if CREAD is not set
	 */
	if ((cflag & CREAD) == 0)
		info->read_status_mask &= ~BD_SC_EMPTY;
	save_flags(flags); cli();

	/* Start bit has not been added (so don't, because we would just
	 * subtract it later), and we need to add one for the number of
	 * stops bits (there is always at least one).
	 */
	bits++;
	if ((idx = info->state->smc_scc_num) < SCC_NUM_BASE) {
		smcp = &immr->im_smc[idx];

		/* Set the mode register.  We want to keep a copy of the
		 * enables, because we want to put them back if they were
		 * present.
		 */
		prev_mode = smcp->smc_smcmr;
		smcp->smc_smcmr = smcr_mk_clen(bits) | cval |  SMCMR_SM_UART;
		smcp->smc_smcmr |= (prev_mode & (SMCMR_REN | SMCMR_TEN));
	}
	else {
		sccp = &immr->im_scc[idx - SCC_IDX_BASE];
		sccp->scc_pmsr = (sbits << 12) | scval;
	}

	m8260_cpm_setbrg(info->state->smc_scc_num, baud_rate);

	restore_flags(flags);
}

static void rs_8xx_put_char(struct tty_struct *tty, unsigned char ch)
{
	ser_info_t *info = (ser_info_t *)tty->driver_data;
	volatile cbd_t	*bdp;

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

	if (!tty)
		return;

	bdp = info->tx_cur;
	while (bdp->cbd_sc & BD_SC_READY);

	*((char *)__va(bdp->cbd_bufaddr)) = ch;
	bdp->cbd_datlen = 1;
	bdp->cbd_sc |= BD_SC_READY;

	/* Get next BD.
	*/
	if (bdp->cbd_sc & BD_SC_WRAP)
		bdp = info->tx_bd_base;
	else
		bdp++;

	info->tx_cur = (cbd_t *)bdp;

}

static int rs_8xx_write(struct tty_struct * tty, int from_user,
		    const unsigned char *buf, int count)
{
	int	c, ret = 0;
	ser_info_t *info = (ser_info_t *)tty->driver_data;
	volatile cbd_t *bdp;

	if (serial_paranoia_check(info, tty->device, "rs_write"))
		return 0;

	if (!tty) 
		return 0;

	bdp = info->tx_cur;

	while (1) {
		c = MIN(count, TX_BUF_SIZE);

		if (c <= 0)
			break;

		if (bdp->cbd_sc & BD_SC_READY) {
			info->flags |= TX_WAKEUP;
			break;
		}

		if (from_user) {
			if (copy_from_user(__va(bdp->cbd_bufaddr), buf, c)) {
				if (!ret)
					ret = -EFAULT;
				break;
			}
		} else {
			memcpy(__va(bdp->cbd_bufaddr), buf, c);
		}

		bdp->cbd_datlen = c;
		bdp->cbd_sc |= BD_SC_READY;

		buf += c;
		count -= c;
		ret += c;

		/* Get next BD.
		*/
		if (bdp->cbd_sc & BD_SC_WRAP)
			bdp = info->tx_bd_base;
		else
			bdp++;
		info->tx_cur = (cbd_t *)bdp;
	}
	return ret;
}

static int rs_8xx_write_room(struct tty_struct *tty)
{
	ser_info_t *info = (ser_info_t *)tty->driver_data;
	int	ret;

	if (serial_paranoia_check(info, tty->device, "rs_write_room"))