serial.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

static unsigned char *tmp_buf;
#ifdef DECLARE_MUTEX
static DECLARE_MUTEX(tmp_buf_sem);
#else
static struct semaphore tmp_buf_sem = MUTEX;
#endif

#ifdef CONFIG_ETRAX_SERIAL_FLUSH_DMA_FAST

/* clock select 10 for timer 1 gives 230400 Hz */
#define FASTTIMER_SELECT (10)
/* we use a source of 230400 Hz and a divider of 15 => 15360 Hz */
#define FASTTIMER_DIV (15)

/* fast flush timer stuff */
static int fast_timer_started = 0;
static unsigned long int fast_timer_ints = 0;

static void _INLINE_ start_flush_timer(void)
{
	if (fast_timer_started)
		return;

	*R_TIMER_CTRL = r_timer_ctrl_shadow = 
		(r_timer_ctrl_shadow &
		 ~IO_MASK(R_TIMER_CTRL, timerdiv1) &
		 ~IO_MASK(R_TIMER_CTRL, tm1) &
		 ~IO_MASK(R_TIMER_CTRL, clksel1)) | 
		IO_FIELD(R_TIMER_CTRL, timerdiv1, FASTTIMER_DIV) |
		IO_STATE(R_TIMER_CTRL, tm1, stop_ld) | 
		IO_FIELD(R_TIMER_CTRL, clksel1, FASTTIMER_SELECT);

	*R_TIMER_CTRL = r_timer_ctrl_shadow = 
		(r_timer_ctrl_shadow & ~IO_MASK(R_TIMER_CTRL, tm1)) |
		IO_STATE(R_TIMER_CTRL, tm1, run);

	/* enable timer1 irq */

	*R_IRQ_MASK0_SET = IO_STATE(R_IRQ_MASK0_SET, timer1, set);

	fast_timer_started = 1;
}
#endif /* CONFIG_ETRAX_SERIAL_FLUSH_DMA_FAST */

/* Calculate the chartime depending on baudrate, numbor of bits etc. */
static void update_char_time(struct e100_serial * info)
{
	tcflag_t cflags = info->tty->termios->c_cflag;
	int bits;

	/* calc. number of bits / data byte */
	/* databits + startbit and 1 stopbit */
	if ((cflags & CSIZE) == CS7)
		bits = 9;
	else
		bits = 10;  

	if (cflags & CSTOPB)     /* 2 stopbits ? */
		bits++;

	if (cflags & PARENB)     /* parity bit ? */
		bits++;

	/* calc timeout */
	info->char_time_usec = ((bits * 1000000) / info->baud) + 1;
}

/*
 * This function maps from the Bxxxx defines in asm/termbits.h into real
 * baud rates.
 */

static int 
cflag_to_baud(unsigned int cflag)
{
	static int baud_table[] = {
		0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400,
		4800, 9600, 19200, 38400 };

	static int ext_baud_table[] = {
		0, 57600, 115200, 230400, 460800, 921600, 1843200, 6250000,
                0, 0, 0, 0, 0, 0, 0, 0 };

	if (cflag & CBAUDEX)
		return ext_baud_table[(cflag & CBAUD) & ~CBAUDEX];
	else 
		return baud_table[cflag & CBAUD];
}

/* and this maps to an etrax100 hardware baud constant */

static unsigned char 
cflag_to_etrax_baud(unsigned int cflag)
{
	char retval;

	static char baud_table[] = {
		-1, -1, -1, -1, -1, -1, -1, 0, 1, 2, -1, 3, 4, 5, 6, 7 };

	static char ext_baud_table[] = {
		-1, 8, 9, 10, 11, 12, 13, 14, -1, -1, -1, -1, -1, -1, -1, -1 };

	if (cflag & CBAUDEX)
		retval = ext_baud_table[(cflag & CBAUD) & ~CBAUDEX];
	else 
		retval = baud_table[cflag & CBAUD];

	if (retval < 0) {
		printk("serdriver tried setting invalid baud rate, flags %x.\n", cflag);
		retval = 5; /* choose default 9600 instead */
	}

	return retval | (retval << 4); /* choose same for both TX and RX */
}


/* Various static support functions */

/* Functions to set or clear DTR/RTS on the requested line */
/* It is complicated by the fact that RTS is a serial port register, while
 * DTR might not be implemented in the HW at all, and if it is, it can be on
 * any general port.
 */


static inline void 
e100_dtr(struct e100_serial *info, int set)
{
#ifndef CONFIG_SVINTO_SIM
	unsigned char mask = e100_modem_pins[info->line].dtr_mask;

#ifdef SERIAL_DEBUG_IO  
	printk("ser%i dtr %i mask: 0x%02X\n", info->line, set, mask);
	printk("ser%i shadow before 0x%02X get: %i\n", 
	       info->line, *e100_modem_pins[info->line].dtr_shadow,
	       E100_DTR_GET(info));
#endif
	/* DTR is active low */
	{
		unsigned long flags;

		save_flags(flags);
		cli();
		*e100_modem_pins[info->line].dtr_shadow &= ~mask;
		*e100_modem_pins[info->line].dtr_shadow |= (set ? 0 : mask); 
		*e100_modem_pins[info->line].dtr_port = *e100_modem_pins[info->line].dtr_shadow;
		restore_flags(flags);
	}
	
#ifdef SERIAL_DEBUG_IO
	printk("ser%i shadow after 0x%02X get: %i\n", 
	       info->line, *e100_modem_pins[info->line].dtr_shadow, 
	       E100_DTR_GET(info));
#endif
#endif
}

/* set = 0 means 3.3V on the pin, bitvalue: 0=active, 1=inactive  
 *                                          0=0V    , 1=3.3V
 */
static inline void 
e100_rts(struct e100_serial *info, int set)
{
#ifndef CONFIG_SVINTO_SIM
	info->rx_ctrl &= ~E100_RTS_MASK;
	info->rx_ctrl |= (set ? 0 : E100_RTS_MASK);  /* RTS is active low */
	info->port[REG_REC_CTRL] = info->rx_ctrl;
#ifdef SERIAL_DEBUG_IO  
	printk("ser%i rts %i\n", info->line, set);
#endif
#endif
}


/* If this behaves as a modem, RI and CD is an output */
static inline void 
e100_ri_out(struct e100_serial *info, int set)
{
#ifndef CONFIG_SVINTO_SIM
	/* RI is active low */
	{
		unsigned char mask = e100_modem_pins[info->line].ri_mask;
		unsigned long flags;

		save_flags(flags);
		cli();
		*e100_modem_pins[info->line].ri_shadow &= ~mask;
		*e100_modem_pins[info->line].ri_shadow |= (set ? 0 : mask); 
		*e100_modem_pins[info->line].ri_port = *e100_modem_pins[info->line].ri_shadow;
		restore_flags(flags);
	}
#endif
}
static inline void 
e100_cd_out(struct e100_serial *info, int set)
{
#ifndef CONFIG_SVINTO_SIM
	/* CD is active low */
	{
		unsigned char mask = e100_modem_pins[info->line].cd_mask;
		unsigned long flags;

		save_flags(flags);
		cli();
		*e100_modem_pins[info->line].cd_shadow &= ~mask;
		*e100_modem_pins[info->line].cd_shadow |= (set ? 0 : mask); 
		*e100_modem_pins[info->line].cd_port = *e100_modem_pins[info->line].cd_shadow;
		restore_flags(flags);
	}
#endif
}

static inline void
e100_disable_rx(struct e100_serial *info)
{
#ifndef CONFIG_SVINTO_SIM
	/* disable the receiver */
	info->port[REG_REC_CTRL] =
		(info->rx_ctrl &= ~IO_MASK(R_SERIAL0_REC_CTRL, rec_enable));
#endif
}

static inline void 
e100_enable_rx(struct e100_serial *info)
{
#ifndef CONFIG_SVINTO_SIM
	/* enable the receiver */
	info->port[REG_REC_CTRL] =
		(info->rx_ctrl |= IO_MASK(R_SERIAL0_REC_CTRL, rec_enable));
#endif
}

/* the rx DMA uses both the dma_descr and the dma_eop interrupts */

static inline void
e100_disable_rxdma_irq(struct e100_serial *info) 
{
#ifdef SERIAL_DEBUG_INTR
	printk("rxdma_irq(%d): 0\n",info->line);
#endif
	*R_IRQ_MASK2_CLR = (info->irq << 2) | (info->irq << 3);
}

static inline void
e100_enable_rxdma_irq(struct e100_serial *info) 
{
#ifdef SERIAL_DEBUG_INTR
	printk("rxdma_irq(%d): 1\n",info->line);
#endif
	*R_IRQ_MASK2_SET = (info->irq << 2) | (info->irq << 3);
}

/* the tx DMA uses only dma_descr interrupt */

static inline void
e100_disable_txdma_irq(struct e100_serial *info) 
{
#ifdef SERIAL_DEBUG_INTR
	printk("txdma_irq(%d): 0\n",info->line);
#endif
	*R_IRQ_MASK2_CLR = info->irq;
}

static inline void
e100_enable_txdma_irq(struct e100_serial *info) 
{
#ifdef SERIAL_DEBUG_INTR
	printk("txdma_irq(%d): 1\n",info->line);
#endif
	*R_IRQ_MASK2_SET = info->irq;
}

#ifdef SERIAL_HANDLE_EARLY_ERRORS
/* in order to detect and fix errors on the first byte
   we have to use the serial interrupts as well. */

static inline void
e100_disable_serial_data_irq(struct e100_serial *info) 
{
#ifdef SERIAL_DEBUG_INTR
	printk("ser_irq(%d): 0\n",info->line);
#endif
	*R_IRQ_MASK1_CLR = (1U << (8+2*info->line));
}

static inline void
e100_enable_serial_data_irq(struct e100_serial *info) 
{
#ifdef SERIAL_DEBUG_INTR
	printk("ser_irq(%d): 1\n",info->line);
	printk("**** %d = %d\n",
	       (8+2*info->line),
	       (1U << (8+2*info->line)));
#endif
	*R_IRQ_MASK1_SET = (1U << (8+2*info->line));
}
#endif

#if defined(CONFIG_ETRAX_RS485)
/* Enable RS-485 mode on selected port. This is UGLY. */
static int
e100_enable_rs485(struct tty_struct *tty,struct rs485_control *r)
{
	struct e100_serial * info = (struct e100_serial *)tty->driver_data;

#if defined(CONFIG_ETRAX_RS485_ON_PA)	
	*R_PORT_PA_DATA = port_pa_data_shadow |= (1 << rs485_pa_bit);
#endif

	info->rs485.rts_on_send = 0x01 & r->rts_on_send;
	info->rs485.rts_after_sent = 0x01 & r->rts_after_sent;
	info->rs485.delay_rts_before_send = r->delay_rts_before_send;
	info->rs485.enabled = r->enabled;
/*	printk("rts: on send = %i, after = %i, enabled = %i",
		    info->rs485.rts_on_send,
		    info->rs485.rts_after_sent,
		    info->rs485.enabled
	);
*/		
	return 0;
}

static int
e100_write_rs485(struct tty_struct *tty, int from_user,
                 const unsigned char *buf, int count)
{
	struct e100_serial * info = (struct e100_serial *)tty->driver_data;
	int old_enabled = info->rs485.enabled;

	/* rs485 is always implicitly enabled if we're using the ioctl() 
	 * but it doesn't have to be set in the rs485_control
	 * (to be backward compatible with old apps)
	 * So we store, set and restore it.
	 */
	info->rs485.enabled = 1;
	/* rs_write now deals with RS485 if enabled */
	count = rs_write(tty, from_user, buf, count);
	info->rs485.enabled = old_enabled;
	return count;
}

#ifdef CONFIG_ETRAX_FAST_TIMER
/* Timer function to toggle RTS when using FAST_TIMER */
static void rs485_toggle_rts_timer_function(unsigned long data)
{
	struct e100_serial *info = (struct e100_serial *)data;

	fast_timers_rs485[info->line].function = NULL;
	e100_rts(info, info->rs485.rts_after_sent);
#if defined(CONFIG_ETRAX_RS485_DISABLE_RECEIVER)
	e100_enable_rx(info);
	e100_enable_rxdma_irq(info);
#endif
}
#endif
#endif /* CONFIG_ETRAX_RS485 */

/*
 * ------------------------------------------------------------
 * rs_stop() and rs_start()
 *
 * This routines are called before setting or resetting tty->stopped.
 * They enable or disable transmitter using the XOFF registers, as necessary.
 * ------------------------------------------------------------
 */

static void 
rs_stop(struct tty_struct *tty)
{
	struct e100_serial *info = (struct e100_serial *)tty->driver_data;
	if (info) {
		unsigned long flags;
		unsigned long xoff;
		
		save_flags(flags); cli();
		xoff = IO_FIELD(R_SERIAL0_XOFF, xoff_char, STOP_CHAR(info->tty));
		xoff |= IO_STATE(R_SERIAL0_XOFF, tx_stop, stop);
		if (tty->termios->c_iflag & IXON ) {
			xoff |= IO_STATE(R_SERIAL0_XOFF, auto_xoff, enable);
		}
	
		*((unsigned long *)&info->port[REG_XOFF]) = xoff;
		restore_flags(flags);
	}
}

static void 
rs_start(struct tty_struct *tty)
{
	struct e100_serial *info = (struct e100_serial *)tty->driver_data;
	if (info) {
		unsigned long flags;
		unsigned long xoff;

		save_flags(flags); cli();
		xoff = IO_FIELD(R_SERIAL0_XOFF, xoff_char, STOP_CHAR(tty));
		xoff |= IO_STATE(R_SERIAL0_XOFF, tx_stop, enable);
		if (tty->termios->c_iflag & IXON ) {
			xoff |= IO_STATE(R_SERIAL0_XOFF, auto_xoff, enable);
		}
	
		*((unsigned long *)&info->port[REG_XOFF]) = xoff;
		
		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(struct e100_serial *info,
				    int event)
{
	info->event |= 1 << event;