path: root/drivers/tty/serial/68328serial.c

/* 68328serial.c: Serial port driver for 68328 microcontroller
 *
 * Copyright (C) 1995       David S. Miller    <davem@caip.rutgers.edu>
 * Copyright (C) 1998       Kenneth Albanowski <kjahds@kjahds.com>
 * Copyright (C) 1998, 1999 D. Jeff Dionne     <jeff@uclinux.org>
 * Copyright (C) 1999       Vladimir Gurevich  <vgurevic@cisco.com>
 * Copyright (C) 2002-2003  David McCullough   <davidm@snapgear.com>
 * Copyright (C) 2002       Greg Ungerer       <gerg@snapgear.com>
 *
 * VZ Support/Fixes             Evan Stawnyczy <e@lineo.ca>
 * Multiple UART support        Daniel Potts <danielp@cse.unsw.edu.au>
 * Power management support     Daniel Potts <danielp@cse.unsw.edu.au>
 * VZ Second Serial Port enable Phil Wilshire
 * 2.4/2.5 port                 David McCullough
 */

#include <asm/dbg.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/serial.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.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/mm.h>
#include <linux/kernel.h>
#include <linux/console.h>
#include <linux/reboot.h>
#include <linux/keyboard.h>
#include <linux/init.h>
#include <linux/pm.h>
#include <linux/bitops.h>
#include <linux/delay.h>
#include <linux/gfp.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/delay.h>
#include <asm/uaccess.h>

/* (es) */
/* note: perhaps we can murge these files, so that you can just
 * 	 define 1 of them, and they can sort that out for themselves
 */
#if defined(CONFIG_M68EZ328)
#include <asm/MC68EZ328.h>
#else
#if defined(CONFIG_M68VZ328)
#include <asm/MC68VZ328.h>
#else
#include <asm/MC68328.h>
#endif /* CONFIG_M68VZ328 */
#endif /* CONFIG_M68EZ328 */

/* Turn off usage of real serial interrupt code, to "support" Copilot */
#ifdef CONFIG_XCOPILOT_BUGS
#undef USE_INTS
#else
#define USE_INTS
#endif

/*
 * I believe this is the optimal setting that reduces the number of interrupts.
 * At high speeds the output might become a little "bursted" (use USTCNT_TXHE
 * if that bothers you), but in most cases it will not, since we try to
 * transmit characters every time rs_interrupt is called. Thus, quite often
 * you'll see that a receive interrupt occures before the transmit one.
 *                                  -- Vladimir Gurevich
 */
#define USTCNT_TX_INTR_MASK (USTCNT_TXEE)

/*
 * 68328 and 68EZ328 UARTS are a little bit different. EZ328 has special
 * "Old data interrupt" which occures whenever the data stay in the FIFO
 * longer than 30 bits time. This allows us to use FIFO without compromising
 * latency. '328 does not have this feature and without the real  328-based
 * board I would assume that RXRE is the safest setting.
 *
 * For EZ328 I use RXHE (Half empty) interrupt to reduce the number of
 * interrupts. RXFE (receive queue full) causes the system to lose data
 * at least at 115200 baud
 *
 * If your board is busy doing other stuff, you might consider to use
 * RXRE (data ready intrrupt) instead.
 *
 * The other option is to make these INTR masks run-time configurable, so
 * that people can dynamically adapt them according to the current usage.
 *                                  -- Vladimir Gurevich
 */

/* (es) */
#if defined(CONFIG_M68EZ328) || defined(CONFIG_M68VZ328)
#define USTCNT_RX_INTR_MASK (USTCNT_RXHE | USTCNT_ODEN)
#elif defined(CONFIG_M68328)
#define USTCNT_RX_INTR_MASK (USTCNT_RXRE)
#else
#error Please, define the Rx interrupt events for your CPU
#endif
/* (/es) */

/*
 * This is our internal structure for each serial port's state.
 */
struct m68k_serial {
	struct tty_port		tport;
	char			is_cons;	/* Is this our console. */
	int			magic;
	int			baud_base;
	int			port;
	int			irq;
	int			type;		/* UART type */
	int			custom_divisor;
	int			x_char;		/* xon/xoff character */
	int			line;
	unsigned char		*xmit_buf;
	int			xmit_head;
	int			xmit_tail;
	int			xmit_cnt;
};

#define SERIAL_MAGIC 0x5301

/*
 * Define the number of ports supported and their irqs.
 */
#define NR_PORTS 1

static struct m68k_serial m68k_soft[NR_PORTS];

static unsigned</