serial-sa11x0.c

arm7,44b0芯片的blob程序,适用于学嵌入式linux的新手.

/*
 * serial-sa11x0.c: StrongARM SA11x0 serial port driver
 *
 * Copyright (C) 2002  Erik Mouw <[e-mail]>
 *
 * $Id: serial-sa11x0.c,v 1.2 2002/01/03 16:07:18 erikm Exp $
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */

#ident "$Id: serial-sa11x0.c,v 1.2 2002/01/03 16:07:18 erikm Exp $"

#ifdef HAVE_CONFIG_H
# include <blob/config.h>
#endif

#include <blob/arch.h>
#include <blob/errno.h>
#include <blob/sa1100.h>
#include <blob/serial.h>
#include <blob/types.h>




#if defined USE_SERIAL1

# define SerialUTSR0 Ser1UTSR0
# define SerialUTSR1 Ser1UTSR1

# define SerialUTDR Ser1UTDR

# define SerialUTCR0 Ser1UTCR0
# define SerialUTCR1 Ser1UTCR1
# define SerialUTCR2 Ser1UTCR2
# define SerialUTCR3 Ser1UTCR3

#else /* defined USE_SERIAL3 */

/* using an SA11x0 CPU and not having any serial port defined is an
 * error, but because we're using the driver in the library we can't
 * bail out over here
 */

# define SerialUTSR0 Ser3UTSR0
# define SerialUTSR1 Ser3UTSR1

# define SerialUTDR Ser3UTDR

# define SerialUTCR0 Ser3UTCR0
# define SerialUTCR1 Ser3UTCR1
# define SerialUTCR2 Ser3UTCR2
# define SerialUTCR3 Ser3UTCR3

#endif




/* flush serial input queue. returns 0 on success or negative error
 * number otherwise
 */
static int sa11x0_serial_flush_input(void)
{
	volatile u32 tmp;

	/* keep on reading as long as the receiver is not empty */
	while(SerialUTSR1 & UTSR1_RNE) {
		if(SerialUTSR1 & (UTSR1_PRE | UTSR1_FRE | UTSR1_ROR))
			return -ESERIAL;

		tmp = SerialUTDR;
	}

	return 0;
}




/* flush output queue. returns 0 on success or negative error number
 * otherwise
 */
static int sa11x0_serial_flush_output(void)
{
	/* wait until the transmitter is no longer busy */
	while(SerialUTSR1 & UTSR1_TBY) {
	}

	return 0;
}




/* initialise serial port at the request baudrate. returns 0 on
 * success, or a negative error number otherwise
 */
static int sa11x0_serial_init(serial_baud_t baud)
{
	u32 divisor;

	/* get correct divisor */
	switch(baud) {
	case baud_1200:
		divisor = 191;
		break;

	case baud_9600:
		divisor = 23;
		break;

	case baud_19200:
		divisor = 11;
		break;

	case baud_38400:
		divisor = 5;
		break;

	case baud_57600:
		divisor = 3;
		break;

	case baud_115200:
		divisor = 1;
		break;

	case baud_230400:
		divisor = 0;
		break;

	default:
		return -ERANGE;
	}

#if defined USE_SERIAL1
	/* select UART use for serial port 1 or otherwise we won't see
	 * anything at all */
	Ser1SDCR0 = SDCR0_UART;
#endif	

	sa11x0_serial_flush_output();

	/* switch receiver and transmitter off */
	SerialUTCR3 = 0x00;
	
	/* clear sticky bits in control register 3 */
	SerialUTSR0 = 0xff;

	/* set the port to sensible defaults (no break, no interrupts,
	 * no parity, 8 databits, 1 stopbit, transmitter and receiver
	 * enabled)
	 */
	SerialUTCR0 = ( UTCR0_1StpBit | UTCR0_8BitData );
	SerialUTCR1 = 0;
	SerialUTCR2 = divisor;

	/* turn the receiver and transmitter back on */
	SerialUTCR3 = ( UTCR3_RXE | UTCR3_TXE );

	return 0;
}




/* check if there is a character available to read. returns 1 if there
 * is a character available, 0 if not, and negative error number on
 * failure */
static int sa11x0_serial_poll(void)
{
	/* check for errors */
	if(SerialUTSR1 & (UTSR1_PRE | UTSR1_FRE | UTSR1_ROR))
		return -ESERIAL;

	if(SerialUTSR1 & UTSR1_RNE)
		return 1;
	else
		return 0;
}




/* read one character from the serial port. return character (between
 * 0 and 255) on success, or negative error number on failure. this
 * function is blocking */
static int sa11x0_serial_read(void)
{
	int rv;

	for(;;) {
		rv = sa11x0_serial_poll();

		if(rv < 0)
			return rv;

		if(rv > 0)
			return SerialUTDR & 0xff;
	}
}




/* write character to serial port. return 0 on success, or negative
 * error number on failure. this function is blocking
 */
static int sa11x0_serial_write(int c)
{
	/* wait for room in the transmit FIFO */
	while((SerialUTSR0 & UTSR0_TFS) == 0) {
	}

	SerialUTDR = c & 0xff;

	return 0;
}




/* export serial driver */
serial_driver_t sa11x0_serial_driver = {
	init:		sa11x0_serial_init,
	read:		sa11x0_serial_read,
	write:		sa11x0_serial_write,
	poll:		sa11x0_serial_poll,
	flush_input:	sa11x0_serial_flush_input,
	flush_output:	sa11x0_serial_flush_output
};