amba.c

IXP425 平台下嵌入式LINUX的串口的驱动程序

/*
 *  linux/drivers/char/serial_amba.c
 *
 *  Driver for AMBA serial ports
 *
 *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
 *
 *  Copyright 1999 ARM Limited
 *  Copyright (C) 2000 Deep Blue Solutions Ltd.
 *
 * 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
 *
 *  $Id: amba.c,v 1.9.2.2 2002/10/24 09:53:25 rmk Exp $
 *
 * This is a generic driver for ARM AMBA-type serial ports.  They
 * have a lot of 16550-like features, but are not register compatable.
 * Note that although they do have CTS, DCD and DSR inputs, they do
 * not have an RI input, nor do they have DTR or RTS outputs.  If
 * required, these have to be supplied via some other means (eg, GPIO)
 * and hooked into this driver.
 */
#include <linux/config.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.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/ptrace.h>
#include <linux/ioport.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/circ_buf.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/sysrq.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/uaccess.h>
#include <asm/bitops.h>

#if defined(CONFIG_SERIAL_AMBA_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/serial_core.h>

#include <asm/hardware/serial_amba.h>

#define UART_NR		2

#define SERIAL_AMBA_MAJOR	204
#define SERIAL_AMBA_MINOR	16
#define SERIAL_AMBA_NR		UART_NR

#define CALLOUT_AMBA_NAME	"cuaam"
#define CALLOUT_AMBA_MAJOR	205
#define CALLOUT_AMBA_MINOR	16
#define CALLOUT_AMBA_NR		UART_NR

static struct tty_driver normal, callout;
static struct tty_struct *amba_table[UART_NR];
static struct termios *amba_termios[UART_NR], *amba_termios_locked[UART_NR];
#ifdef SUPPORT_SYSRQ
static struct console amba_console;
#endif

#define AMBA_ISR_PASS_LIMIT	256

/*
 * Access macros for the AMBA UARTs
 */
#define UART_GET_INT_STATUS(p)	readb((p)->membase + AMBA_UARTIIR)
#define UART_PUT_ICR(p, c)	writel((c), (p)->membase + AMBA_UARTICR)
#define UART_GET_FR(p)		readb((p)->membase + AMBA_UARTFR)
#define UART_GET_CHAR(p)	readb((p)->membase + AMBA_UARTDR)
#define UART_PUT_CHAR(p, c)	writel((c), (p)->membase + AMBA_UARTDR)
#define UART_GET_RSR(p)		readb((p)->membase + AMBA_UARTRSR)
#define UART_GET_CR(p)		readb((p)->membase + AMBA_UARTCR)
#define UART_PUT_CR(p,c)	writel((c), (p)->membase + AMBA_UARTCR)
#define UART_GET_LCRL(p)	readb((p)->membase + AMBA_UARTLCR_L)
#define UART_PUT_LCRL(p,c)	writel((c), (p)->membase + AMBA_UARTLCR_L)
#define UART_GET_LCRM(p)	readb((p)->membase + AMBA_UARTLCR_M)
#define UART_PUT_LCRM(p,c)	writel((c), (p)->membase + AMBA_UARTLCR_M)
#define UART_GET_LCRH(p)	readb((p)->membase + AMBA_UARTLCR_H)
#define UART_PUT_LCRH(p,c)	writel((c), (p)->membase + AMBA_UARTLCR_H)
#define UART_RX_DATA(s)		(((s) & AMBA_UARTFR_RXFE) == 0)
#define UART_TX_READY(s)	(((s) & AMBA_UARTFR_TXFF) == 0)
#define UART_TX_EMPTY(p)	((UART_GET_FR(p) & AMBA_UARTFR_TMSK) == 0)

#define UART_DUMMY_RSR_RX	256
#define UART_PORT_SIZE		64

/*
 * On the Integrator platform, the port RTS and DTR are provided by
 * bits in the following SC_CTRLS register bits:
 *        RTS  DTR
 *  UART0  7    6
 *  UART1  5    4
 *
 * We encode this bit information into port->driver_priv using the
 * following macros.
 */
//#define PORT_CTRLS(dtrbit,rtsbit)	((1 << dtrbit) | (1 << (16 + rtsbit)))
#define PORT_CTRLS_DTR(port)		(1 << (port)->unused[1])
#define PORT_CTRLS_RTS(port)		(1 << (port)->unused[0])

#define SC_CTRLC	(IO_ADDRESS(INTEGRATOR_SC_BASE) + INTEGRATOR_SC_CTRLC_OFFSET)
#define SC_CTRLS	(IO_ADDRESS(INTEGRATOR_SC_BASE) + INTEGRATOR_SC_CTRLS_OFFSET)

/*
 * Our private driver data mappings.
 */
#define drv_old_status	driver_priv

static void ambauart_stop_tx(struct uart_port *port, u_int from_tty)
{
	unsigned int cr;

	cr = UART_GET_CR(port);
	cr &= ~AMBA_UARTCR_TIE;
	UART_PUT_CR(port, cr);
}

static void ambauart_start_tx(struct uart_port *port, u_int nonempty, u_int from_tty)
{
	if (nonempty) {
		unsigned int cr;

		cr = UART_GET_CR(port);
		cr |= AMBA_UARTCR_TIE;
		UART_PUT_CR(port, cr);
	}
}

static void ambauart_stop_rx(struct uart_port *port)
{
	unsigned int cr;

	cr = UART_GET_CR(port);
	cr &= ~(AMBA_UARTCR_RIE | AMBA_UARTCR_RTIE);
	UART_PUT_CR(port, cr);
}

static void ambauart_enable_ms(struct uart_port *port)
{
	unsigned int cr;

	cr = UART_GET_CR(port);
	cr |= AMBA_UARTCR_MSIE;
	UART_PUT_CR(port, cr);
}

static void
#ifdef SUPPORT_SYSRQ
ambauart_rx_chars(struct uart_info *info, struct pt_regs *regs)
#else
ambauart_rx_chars(struct uart_info *info)
#endif
{
	struct tty_struct *tty = info->tty;
	unsigned int status, ch, rsr, max_count = 256;
	struct uart_port *port = info->port;

	status = UART_GET_FR(port);
	while (UART_RX_DATA(status) && max_count--) {
		if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
			tty->flip.tqueue.routine((void *)tty);
			if (tty->flip.count >= TTY_FLIPBUF_SIZE) {
				printk(KERN_WARNING "TTY_DONT_FLIP set\n");
				return;
			}
		}

		ch = UART_GET_CHAR(port);

		*tty->flip.char_buf_ptr = ch;
		*tty->flip.flag_buf_ptr = TTY_NORMAL;
		port->icount.rx++;

		/*
		 * Note that the error handling code is
		 * out of the main execution path
		 */
		rsr = UART_GET_RSR(port) | UART_DUMMY_RSR_RX;
		if (rsr & AMBA_UARTRSR_ANY) {
			if (rsr & AMBA_UARTRSR_BE) {
				rsr &= ~(AMBA_UARTRSR_FE | AMBA_UARTRSR_PE);
				port->icount.brk++;
				if (uart_handle_break(info, &amba_console))
					goto ignore_char;
			} else if (rsr & AMBA_UARTRSR_PE)
				port->icount.parity++;
			else if (rsr & AMBA_UARTRSR_FE)
				port->icount.frame++;
			if (rsr & AMBA_UARTRSR_OE)
				port->icount.overrun++;

			rsr &= port->read_status_mask;

			if (rsr & AMBA_UARTRSR_BE)
				*tty->flip.flag_buf_ptr = TTY_BREAK;
			else if (rsr & AMBA_UARTRSR_PE)
				*tty->flip.flag_buf_ptr = TTY_PARITY;
			else if (rsr & AMBA_UARTRSR_FE)
				*tty->flip.flag_buf_ptr = TTY_FRAME;
		}

		if (uart_handle_sysrq_char(info, ch, regs))
			goto ignore_char;

		if ((rsr & port->ignore_status_mask) == 0) {
			tty->flip.flag_buf_ptr++;
			tty->flip.char_buf_ptr++;
			tty->flip.count++;
		}
		if ((rsr & AMBA_UARTRSR_OE) &&
		    tty->flip.count < TTY_FLIPBUF_SIZE) {
			/*
			 * Overrun is special, since it's reported
			 * immediately, and doesn't affect the current
			 * character
			 */
			*tty->flip.char_buf_ptr++ = 0;
			*tty->flip.flag_buf_ptr++ = TTY_OVERRUN;
			tty->flip.count++;
		}
	ignore_char:
		status = UART_GET_FR(port);
	}
	tty_flip_buffer_push(tty);
	return;
}

static void ambauart_tx_chars(struct uart_info *info)
{
	struct uart_port *port = info->port;
	int count;

	if (port->x_char) {
		UART_PUT_CHAR(port, port->x_char);
		port->icount.tx++;
		port->x_char = 0;
		return;
	}
	if (info->xmit.head == info->xmit.tail
	    || info->tty->stopped
	    || info->tty->hw_stopped) {
		ambauart_stop_tx(port, 0);
		return;
	}

	count = port->fifosize >> 1;
	do {
		UART_PUT_CHAR(port, info->xmit.buf[info->xmit.tail]);
		info->xmit.tail = (info->xmit.tail + 1) & (UART_XMIT_SIZE - 1);
		port->icount.tx++;
		if (info->xmit.head == info->xmit.tail)
			break;
	} while (--count > 0);

	if (CIRC_CNT(info->xmit.head, info->xmit.tail, UART_XMIT_SIZE) <
			WAKEUP_CHARS)
		uart_event(info, EVT_WRITE_WAKEUP);

	if (info->xmit.head == info->xmit.tail)
		ambauart_stop_tx(info->port, 0);
}

static void ambauart_modem_status(struct uart_info *info)
{
	struct uart_port *port = info->port;
	unsigned int status, delta;

	UART_PUT_ICR(port, 0);

	status = UART_GET_FR(port) & AMBA_UARTFR_MODEM_ANY;

	delta = status ^ info->drv_old_status;
	info->drv_old_status = status;

	if (!delta)
		return;

	if (delta & AMBA_UARTFR_DCD)
		uart_handle_dcd_change(info, status & AMBA_UARTFR_DCD);

	if (delta & AMBA_UARTFR_DSR)
		port->icount.dsr++;

	if (delta & AMBA_UARTFR_CTS)
		uart_handle_cts_change(info, status & AMBA_UARTFR_CTS);

	wake_up_interruptible(&info->delta_msr_wait);
}

static void ambauart_int(int irq, void *dev_id, struct pt_regs *regs)
{
	struct uart_info *info = dev_id;
	unsigned int status, pass_counter = AMBA_ISR_PASS_LIMIT;

	status = UART_GET_INT_STATUS(info->port);
	do {
		if (status & (AMBA_UARTIIR_RTIS | AMBA_UARTIIR_RIS))
#ifdef SUPPORT_SYSRQ
			ambauart_rx_chars(info, regs);
#else
			ambauart_rx_chars(info);
#endif
		if (status & AMBA_UARTIIR_TIS)
			ambauart_tx_chars(info);
		if (status & AMBA_UARTIIR_MIS)
			ambauart_modem_status(info);

		if (pass_counter-- == 0)
			break;

		status = UART_GET_INT_STATUS(info->port);
	} while (status & (AMBA_UARTIIR_RTIS | AMBA_UARTIIR_RIS |
			   AMBA_UARTIIR_TIS));
}

static u_int ambauart_tx_empty(struct uart_port *port)
{
	return UART_GET_FR(port) & AMBA_UARTFR_BUSY ? 0 : TIOCSER_TEMT;
}

static u_int ambauart_get_mctrl(struct uart_port *port)
{
	unsigned int result = 0;
	unsigned int status;

	status = UART_GET_FR(port);
	if (status & AMBA_UARTFR_DCD)
		result |= TIOCM_CAR;
	if (status & AMBA_UARTFR_DSR)
		result |= TIOCM_DSR;
	if (status & AMBA_UARTFR_CTS)
		result |= TIOCM_CTS;

	return result;
}

static void ambauart_set_mctrl(struct uart_port *port, u_int mctrl)
{
	u_int ctrls = 0, ctrlc = 0;

	if (mctrl & TIOCM_RTS)
		ctrlc |= PORT_CTRLS_RTS(port);
	else
		ctrls |= PORT_CTRLS_RTS(port);

	if (mctrl & TIOCM_DTR)
		ctrlc |= PORT_CTRLS_DTR(port);
	else
		ctrls |= PORT_CTRLS_DTR(port);

	__raw_writel(ctrls, SC_CTRLS);
	__raw_writel(ctrlc, SC_CTRLC);
}