serial_amba.c

Linux内核源代码 为压缩文件 是<<Linux内核>>一书中的源代码

/*
 *  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
 *
 *
 * 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.
 *
 * This could very easily become a generic serial driver for dumb UARTs
 * (eg, {82,16x}50, 21285, SA1100).
 */

#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/malloc.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>

#include <asm/hardware/serial_amba.h>

#define SERIAL_AMBA_NAME	"ttyAM"
#define SERIAL_AMBA_MAJOR	204
#define SERIAL_AMBA_MINOR	16
#define SERIAL_AMBA_NR		2

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

#ifndef TRUE
#define TRUE 1
#endif
#ifndef FALSE
#define FALSE 0
#endif

#define DEBUG 0
#define DEBUG_LEDS 0

#if DEBUG_LEDS
extern int get_leds(void);
extern int set_leds(int);
#endif

/*
 * Access routines for the AMBA UARTs
 */
#define UART_GET_INT_STATUS(p)	IO_READ((p)->uart_base + AMBA_UARTIIR)
#define UART_GET_FR(p)		IO_READ((p)->uart_base + AMBA_UARTFR)
#define UART_GET_CHAR(p)	IO_READ((p)->uart_base + AMBA_UARTDR)
#define UART_PUT_CHAR(p, c)	IO_WRITE((p)->uart_base + AMBA_UARTDR, (c))
#define UART_GET_RSR(p)		IO_READ((p)->uart_base + AMBA_UARTRSR)
#define UART_GET_CR(p)		IO_READ((p)->uart_base + AMBA_UARTCR)
#define UART_PUT_CR(p,c)	IO_WRITE((p)->uart_base + AMBA_UARTCR, (c))
#define UART_GET_LCRL(p)	IO_READ((p)->uart_base + AMBA_UARTLCR_L)
#define UART_PUT_LCRL(p,c)	IO_WRITE((p)->uart_base + AMBA_UARTLCR_L, (c))
#define UART_GET_LCRM(p)	IO_READ((p)->uart_base + AMBA_UARTLCR_M)
#define UART_PUT_LCRM(p,c)	IO_WRITE((p)->uart_base + AMBA_UARTLCR_M, (c))
#define UART_GET_LCRH(p)	IO_READ((p)->uart_base + AMBA_UARTLCR_H)
#define UART_PUT_LCRH(p,c)	IO_WRITE((p)->uart_base + AMBA_UARTLCR_H, (c))
#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 AMBA_UARTRSR_ANY	(AMBA_UARTRSR_OE|AMBA_UARTRSR_BE|AMBA_UARTRSR_PE|AMBA_UARTRSR_FE)
#define AMBA_UARTFR_MODEM_ANY	(AMBA_UARTFR_DCD|AMBA_UARTFR_DSR|AMBA_UARTFR_CTS)

/*
 * Things needed by tty driver
 */
static struct tty_driver ambanormal_driver, ambacallout_driver;
static int ambauart_refcount;
static struct tty_struct *ambauart_table[SERIAL_AMBA_NR];
static struct termios *ambauart_termios[SERIAL_AMBA_NR];
static struct termios *ambauart_termios_locked[SERIAL_AMBA_NR];

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

/*
 * Things needed internally to this driver
 */

/*
 * tmp_buf is used as a temporary buffer by serial_write.  We need to
 * lock it in case the copy_from_user 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 u_char *tmp_buf;
static DECLARE_MUTEX(tmp_buf_sem);

#define HIGH_BITS_OFFSET	((sizeof(long)-sizeof(int))*8)

/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS		256
#define AMBA_ISR_PASS_LIMIT	256

#define EVT_WRITE_WAKEUP	0

struct amba_icount {
	__u32	cts;
	__u32	dsr;
	__u32	rng;
	__u32	dcd;
	__u32	rx;
	__u32	tx;
	__u32	frame;
	__u32	overrun;
	__u32	parity;
	__u32	brk;
	__u32	buf_overrun;
};

/*
 * Static information about the port
 */
struct amba_port {
	unsigned int		uart_base;
	unsigned int		irq;
	unsigned int		uartclk;
	unsigned int		fifosize;
	unsigned int		tiocm_support;
	void (*set_mctrl)(struct amba_port *, u_int mctrl);
};	

/*
 * This is the state information which is persistent across opens
 */
struct amba_state {
	struct amba_icount	icount;
	unsigned int		line;
	unsigned int		close_delay;
	unsigned int		closing_wait;
	unsigned int		custom_divisor;
	unsigned int		flags;
	struct termios		normal_termios;
	struct termios		callout_termios;

	int			count;
	struct amba_info	*info;
};

#define AMBA_XMIT_SIZE 1024
/*
 * This is the state information which is only valid when the port is open.
 */
struct amba_info {
	struct amba_port	*port;
	struct amba_state	*state;
	struct tty_struct	*tty;
	unsigned char		x_char;
	unsigned char		old_status;
	unsigned char		read_status_mask;
	unsigned char		ignore_status_mask;
	struct circ_buf		xmit;
	unsigned int		flags;
#ifdef SUPPORT_SYSRQ
	unsigned long		sysrq;
#endif

	unsigned int		event;
	unsigned int		timeout;
	unsigned int		lcr_h;
	unsigned int		mctrl;
	int			blocked_open;
	pid_t			session;
	pid_t			pgrp;

	struct tasklet_struct	tlet;

	wait_queue_head_t	open_wait;
	wait_queue_head_t	close_wait;
	wait_queue_head_t	delta_msr_wait;
};

#ifdef CONFIG_SERIAL_AMBA_CONSOLE
static struct console ambauart_cons;
#endif
static void ambauart_change_speed(struct amba_info *info, struct termios *old_termios);
static void ambauart_wait_until_sent(struct tty_struct *tty, int timeout);

#if 1 //def CONFIG_SERIAL_INTEGRATOR
static void amba_set_mctrl_null(struct amba_port *port, u_int mctrl)
{
}

static struct amba_port amba_ports[SERIAL_AMBA_NR] = {
	{
		uart_base:	IO_ADDRESS(INTEGRATOR_UART0_BASE),
		irq:		IRQ_UARTINT0,
		uartclk:	14745600,
		fifosize:	8,
		set_mctrl:	amba_set_mctrl_null,
	},
	{
		uart_base:	IO_ADDRESS(INTEGRATOR_UART1_BASE),
		irq:		IRQ_UARTINT1,
		uartclk:	14745600,
		fifosize:	8,
		set_mctrl:	amba_set_mctrl_null,
	}
};
#endif

static struct amba_state amba_state[SERIAL_AMBA_NR];

static void ambauart_enable_rx_interrupt(struct amba_info *info)
{
	unsigned int cr;

	cr = UART_GET_CR(info->port);
	cr |= AMBA_UARTCR_RIE | AMBA_UARTCR_RTIE;
	UART_PUT_CR(info->port, cr);
}

static void ambauart_disable_rx_interrupt(struct amba_info *info)
{
	unsigned int cr;

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

static void ambauart_enable_tx_interrupt(struct amba_info *info)
{
	unsigned int cr;

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

static void ambauart_disable_tx_interrupt(struct amba_info *info)
{
	unsigned int cr;

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

static void ambauart_stop(struct tty_struct *tty)
{
	struct amba_info *info = tty->driver_data;
	unsigned long flags;

	save_flags(flags); cli();
	ambauart_disable_tx_interrupt(info);
	restore_flags(flags);
}

static void ambauart_start(struct tty_struct *tty)
{
	struct amba_info *info = tty->driver_data;
	unsigned long flags;

	save_flags(flags); cli();
	if (info->xmit.head != info->xmit.tail
	    && info->xmit.buf)
		ambauart_enable_tx_interrupt(info);
	restore_flags(flags);
}


/*
 * This routine is used by the interrupt handler to schedule
 * processing in the software interrupt portion of the driver.
 */
static void ambauart_event(struct amba_info *info, int event)
{
	info->event |= 1 << event;
	tasklet_schedule(&info->tlet);
}

static void
#ifdef SUPPORT_SYSRQ
ambauart_rx_chars(struct amba_info *info, struct pt_regs *regs)
#else
ambauart_rx_chars(struct amba_info *info)
#endif
{
	struct tty_struct *tty = info->tty;
	unsigned int status, ch, rsr, flg, ignored = 0;
	struct amba_icount *icount = &info->state->icount;
	struct amba_port *port = info->port;

	status = UART_GET_FR(port);
	while (UART_RX_DATA(status)) {
		ch = UART_GET_CHAR(port);

		if (tty->flip.count >= TTY_FLIPBUF_SIZE)
			goto ignore_char;
		icount->rx++;

		flg = TTY_NORMAL;

		/*
		 * Note that the error handling code is
		 * out of the main execution path
		 */
		rsr = UART_GET_RSR(port);
		if (rsr & AMBA_UARTRSR_ANY)
			goto handle_error;
#ifdef SUPPORT_SYSRQ
		if (info->sysrq) {
			if (ch && time_before(jiffies, info->sysrq)) {
				handle_sysrq(ch, regs, NULL, NULL);
				info->sysrq = 0;
				goto ignore_char;
			}
			info->sysrq = 0;
		}
#endif
	error_return:
		*tty->flip.flag_buf_ptr++ = flg;
		*tty->flip.char_buf_ptr++ = ch;
		tty->flip.count++;
	ignore_char:
		status = UART_GET_FR(port);
	}
out:
	tty_flip_buffer_push(tty);
	return;

handle_error:
	if (rsr & AMBA_UARTRSR_BE) {
		rsr &= ~(AMBA_UARTRSR_FE | AMBA_UARTRSR_PE);
		icount->brk++;

#ifdef SUPPORT_SYSRQ
		if (info->state->line == ambauart_cons.index) {
			if (!info->sysrq) {
				info->sysrq = jiffies + HZ*5;
				goto ignore_char;
			}
		}
#endif
	} else if (rsr & AMBA_UARTRSR_PE)
		icount->parity++;
	else if (rsr & AMBA_UARTRSR_FE)
		icount->frame++;
	if (rsr & AMBA_UARTRSR_OE)
		icount->overrun++;

	if (rsr & info->ignore_status_mask) {
		if (++ignored > 100)
			goto out;
		goto ignore_char;
	}
	rsr &= info->read_status_mask;

	if (rsr & AMBA_UARTRSR_BE)
		flg = TTY_BREAK;
	else if (rsr & AMBA_UARTRSR_PE)
		flg = TTY_PARITY;
	else if (rsr & AMBA_UARTRSR_FE)
		flg = TTY_FRAME;

	if (rsr & AMBA_UARTRSR_OE) {
		/*
		 * CHECK: does overrun affect the current character?
		 * ASSUMPTION: it does not.
		 */
		*tty->flip.flag_buf_ptr++ = flg;
		*tty->flip.char_buf_ptr++ = ch;
		tty->flip.count++;
		if (tty->flip.count >= TTY_FLIPBUF_SIZE)
			goto ignore_char;
		ch = 0;
		flg = TTY_OVERRUN;
	}
#ifdef SUPPORT_SYSRQ
	info->sysrq = 0;
#endif
	goto error_return;
}

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

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

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

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

	if (info->xmit.head == info->xmit.tail) {
		ambauart_disable_tx_interrupt(info);
	}
}

static void ambauart_modem_status(struct amba_info *info)
{
	unsigned int status, delta;
	struct amba_icount *icount = &info->state->icount;

	status = UART_GET_FR(info->port) & AMBA_UARTFR_MODEM_ANY;

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

	if (!delta)
		return;

	if (delta & AMBA_UARTFR_DCD) {
		icount->dcd++;
#ifdef CONFIG_HARD_PPS
		if ((info->flags & ASYNC_HARDPPS_CD) &&
		    (status & AMBA_UARTFR_DCD)
			hardpps();
#endif
		if (info->flags & ASYNC_CHECK_CD) {
			if (status & AMBA_UARTFR_DCD)
				wake_up_interruptible(&info->open_wait);
			else if (!((info->flags & ASYNC_CALLOUT_ACTIVE) &&
				   (info->flags & ASYNC_CALLOUT_NOHUP))) {
				if (info->tty)
					tty_hangup(info->tty);
			}
		}
	}

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

	if (delta & AMBA_UARTFR_CTS) {
		icount->cts++;

		if (info->flags & ASYNC_CTS_FLOW) {
			status &= AMBA_UARTFR_CTS;

			if (info->tty->hw_stopped) {
				if (status) {