esp.c

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/*
 *  esp.c - driver for Hayes ESP serial cards
 *
 *  --- Notices from serial.c, upon which this driver is based ---
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Extensively rewritten by Theodore Ts'o, 8/16/92 -- 9/14/92.  Now
 *  much more extensible to support other serial cards based on the
 *  16450/16550A UART's.  Added support for the AST FourPort and the
 *  Accent Async board.  
 *
 *  set_serial_info fixed to set the flags, custom divisor, and uart
 * 	type fields.  Fix suggested by Michael K. Johnson 12/12/92.
 *
 *  11/95: TIOCMIWAIT, TIOCGICOUNT by Angelo Haritsis <[e-mail]>
 *
 *  03/96: Modularised by Angelo Haritsis <[e-mail]>
 *
 *  rs_set_termios fixed to look also for changes of the input
 *      flags INPCK, BRKINT, PARMRK, IGNPAR and IGNBRK.
 *                                            Bernd Anh鋟pl 05/17/96.
 *
 * --- End of notices from serial.c ---
 *
 * Support for the ESP serial card by Andrew J. Robinson
 *     <[e-mail]> (Card detection routine taken from a patch
 *     by Dennis J. Boylan).  Patches to allow use with 2.1.x contributed
 *     by Chris Faylor.
 *
 * Most recent changes: (Andrew J. Robinson)
 *   Support for PIO mode.  This allows the driver to work properly with
 *     multiport cards.
 *
 * Arnaldo Carvalho de Melo <[e-mail]> -
 * several cleanups, use module_init/module_exit, etc
 *
 * This module exports the following rs232 io functions:
 *
 *	int espserial_init(void);
 */

#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/serial.h>
#include <linux/serialP.h>
#include <linux/serial_reg.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/init.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/segment.h>
#include <asm/bitops.h>

#include <asm/dma.h>
#include <linux/slab.h>
#include <asm/uaccess.h>

#include <linux/hayesesp.h>

#define NR_PORTS 64	/* maximum number of ports */
#define NR_PRIMARY 8	/* maximum number of primary ports */

/* The following variables can be set by giving module options */
static int irq[NR_PRIMARY];	/* IRQ for each base port */
static unsigned int divisor[NR_PRIMARY]; /* custom divisor for each port */
static unsigned int dma = ESP_DMA_CHANNEL; /* DMA channel */
static unsigned int rx_trigger = ESP_RX_TRIGGER;
static unsigned int tx_trigger = ESP_TX_TRIGGER;
static unsigned int flow_off = ESP_FLOW_OFF;
static unsigned int flow_on = ESP_FLOW_ON;
static unsigned int rx_timeout = ESP_RX_TMOUT;
static unsigned int pio_threshold = ESP_PIO_THRESHOLD;

MODULE_LICENSE("GPL");

MODULE_PARM(irq, "1-8i");
MODULE_PARM(divisor, "1-8i");
MODULE_PARM(dma, "i");
MODULE_PARM(rx_trigger, "i");
MODULE_PARM(tx_trigger, "i");
MODULE_PARM(flow_off, "i");
MODULE_PARM(flow_on, "i");
MODULE_PARM(rx_timeout, "i");
MODULE_PARM(pio_threshold, "i");

/* END */

static char *dma_buffer;
static int dma_bytes;
static struct esp_pio_buffer *free_pio_buf;

#define DMA_BUFFER_SZ 1024

#define WAKEUP_CHARS 1024

static char serial_name[] __initdata = "ESP serial driver";
static char serial_version[] __initdata = "2.2";

static DECLARE_TASK_QUEUE(tq_esp);

static struct tty_driver esp_driver, esp_callout_driver;
static int serial_refcount;

/* serial subtype definitions */
#define SERIAL_TYPE_NORMAL	1
#define SERIAL_TYPE_CALLOUT	2

/*
 * Serial driver configuration section.  Here are the various options:
 *
 * SERIAL_PARANOIA_CHECK
 * 		Check the magic number for the esp_structure where
 * 		ever possible.
 */

#undef SERIAL_PARANOIA_CHECK
#define SERIAL_DO_RESTART

#undef SERIAL_DEBUG_INTR
#undef SERIAL_DEBUG_OPEN
#undef SERIAL_DEBUG_FLOW

#define _INLINE_ inline
  
#if defined(MODULE) && defined(SERIAL_DEBUG_MCOUNT)
#define DBG_CNT(s) printk("(%s): [%x] refc=%d, serc=%d, ttyc=%d -> %s\n", \
 kdevname(tty->device), (info->flags), serial_refcount,info->count,tty->count,s)
#else
#define DBG_CNT(s)
#endif

static struct esp_struct *ports;

static void change_speed(struct esp_struct *info);
static void rs_wait_until_sent(struct tty_struct *, int);
	
/*
 * The ESP card has a clock rate of 14.7456 MHz (that is, 2**ESPC_SCALE
 * times the normal 1.8432 Mhz clock of most serial boards).
 */
#define BASE_BAUD ((1843200 / 16) * (1 << ESPC_SCALE))

/* Standard COM flags (except for COM4, because of the 8514 problem) */
#define STD_COM_FLAGS (ASYNC_BOOT_AUTOCONF | ASYNC_SKIP_TEST)

static struct tty_struct *serial_table[NR_PORTS];
static struct termios *serial_termios[NR_PORTS];
static struct termios *serial_termios_locked[NR_PORTS];

#ifndef MIN
#define MIN(a,b)	((a) < (b) ? (a) : (b))
#endif

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

static inline int serial_paranoia_check(struct esp_struct *info,
					kdev_t device, const char *routine)
{
#ifdef SERIAL_PARANOIA_CHECK
	static const char badmagic[] = KERN_WARNING
		"Warning: bad magic number for serial struct (%s) in %s\n";
	static const char badinfo[] = KERN_WARNING
		"Warning: null esp_struct for (%s) in %s\n";

	if (!info) {
		printk(badinfo, kdevname(device), routine);
		return 1;
	}
	if (info->magic != ESP_MAGIC) {
		printk(badmagic, kdevname(device), routine);
		return 1;
	}
#endif
	return 0;
}

static inline unsigned int serial_in(struct esp_struct *info, int offset)
{
	return inb(info->port + offset);
}

static inline void serial_out(struct esp_struct *info, int offset,
			      unsigned char value)
{
	outb(value, info->port+offset);
}

/*
 * ------------------------------------------------------------
 * rs_stop() and rs_start()
 *
 * This routines are called before setting or resetting tty->stopped.
 * They enable or disable transmitter interrupts, as necessary.
 * ------------------------------------------------------------
 */
static void rs_stop(struct tty_struct *tty)
{
	struct esp_struct *info = (struct esp_struct *)tty->driver_data;
	unsigned long flags;

	if (serial_paranoia_check(info, tty->device, "rs_stop"))
		return;
	
	save_flags(flags); cli();
	if (info->IER & UART_IER_THRI) {
		info->IER &= ~UART_IER_THRI;
		serial_out(info, UART_ESI_CMD1, ESI_SET_SRV_MASK);
		serial_out(info, UART_ESI_CMD2, info->IER);
	}

	restore_flags(flags);
}

static void rs_start(struct tty_struct *tty)
{
	struct esp_struct *info = (struct esp_struct *)tty->driver_data;
	unsigned long flags;
	
	if (serial_paranoia_check(info, tty->device, "rs_start"))
		return;
	
	save_flags(flags); cli();
	if (info->xmit_cnt && info->xmit_buf && !(info->IER & UART_IER_THRI)) {
		info->IER |= UART_IER_THRI;
		serial_out(info, UART_ESI_CMD1, ESI_SET_SRV_MASK);
		serial_out(info, UART_ESI_CMD2, info->IER);
	}
	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 esp_struct *info,
				  int event)
{
	info->event |= 1 << event;
	queue_task(&info->tqueue, &tq_esp);
	mark_bh(ESP_BH);
}
static _INLINE_ struct esp_pio_buffer *get_pio_buffer(void)
{
	struct esp_pio_buffer *buf;

	if (free_pio_buf) {
		buf = free_pio_buf;
		free_pio_buf = buf->next;
	} else {
		buf = kmalloc(sizeof(struct esp_pio_buffer), GFP_ATOMIC);
	}

	return buf;
}

static _INLINE_ void release_pio_buffer(struct esp_pio_buffer *buf)
{
	buf->next = free_pio_buf;
	free_pio_buf = buf;
}

static _INLINE_ void receive_chars_pio(struct esp_struct *info, int num_bytes)
{
	struct tty_struct *tty = info->tty;
	int i;
	struct esp_pio_buffer *pio_buf;
	struct esp_pio_buffer *err_buf;
	unsigned char status_mask;

	pio_buf = get_pio_buffer();

	if (!pio_buf)
		return;

	err_buf = get_pio_buffer();

	if (!err_buf) {
		release_pio_buffer(pio_buf);
		return;
	}

	sti();
	
	status_mask = (info->read_status_mask >> 2) & 0x07;
		
	for (i = 0; i < num_bytes - 1; i += 2) {
		*((unsigned short *)(pio_buf->data + i)) =
			inw(info->port + UART_ESI_RX);
		err_buf->data[i] = serial_in(info, UART_ESI_RWS);
		err_buf->data[i + 1] = (err_buf->data[i] >> 3) & status_mask;
		err_buf->data[i] &= status_mask;
	}

	if (num_bytes & 0x0001) {
		pio_buf->data[num_bytes - 1] = serial_in(info, UART_ESI_RX);
		err_buf->data[num_bytes - 1] =
			(serial_in(info, UART_ESI_RWS) >> 3) & status_mask;
	}

	cli();

	/* make sure everything is still ok since interrupts were enabled */
	tty = info->tty;

	if (!tty) {
		release_pio_buffer(pio_buf);
		release_pio_buffer(err_buf);
		info->stat_flags &= ~ESP_STAT_RX_TIMEOUT;
		return;
	}

	status_mask = (info->ignore_status_mask >> 2) & 0x07;

	for (i = 0; i < num_bytes; i++) {
		if (!(err_buf->data[i] & status_mask)) {
			*(tty->flip.char_buf_ptr++) = pio_buf->data[i];

			if (err_buf->data[i] & 0x04) {
				*(tty->flip.flag_buf_ptr++) = TTY_BREAK;

				if (info->flags & ASYNC_SAK)
					do_SAK(tty);
			}
			else if (err_buf->data[i] & 0x02)
				*(tty->flip.flag_buf_ptr++) = TTY_FRAME;
			else if (err_buf->data[i] & 0x01)
				*(tty->flip.flag_buf_ptr++) = TTY_PARITY;
			else
				*(tty->flip.flag_buf_ptr++) = 0;
		
			tty->flip.count++;
		}
	}

	queue_task(&tty->flip.tqueue, &tq_timer);

	info->stat_flags &= ~ESP_STAT_RX_TIMEOUT;
	release_pio_buffer(pio_buf);
	release_pio_buffer(err_buf);
}

static _INLINE_ void receive_chars_dma(struct esp_struct *info, int num_bytes)
{
	unsigned long flags;
	info->stat_flags &= ~ESP_STAT_RX_TIMEOUT;
	dma_bytes = num_bytes;
	info->stat_flags |= ESP_STAT_DMA_RX;
	
	flags=claim_dma_lock();
        disable_dma(dma);
        clear_dma_ff(dma);
        set_dma_mode(dma, DMA_MODE_READ);
        set_dma_addr(dma, virt_to_bus(dma_buffer));
        set_dma_count(dma, dma_bytes);
        enable_dma(dma);
        release_dma_lock(flags);
        
        serial_out(info, UART_ESI_CMD1, ESI_START_DMA_RX);
}

static _INLINE_ void receive_chars_dma_done(struct esp_struct *info,
					    int status)
{
	struct tty_struct *tty = info->tty;
	int num_bytes;
	unsigned long flags;
	
	
	flags=claim_dma_lock();
	disable_dma(dma);
	clear_dma_ff(dma);

	info->stat_flags &= ~ESP_STAT_DMA_RX;
	num_bytes = dma_bytes - get_dma_residue(dma);
	release_dma_lock(flags);
	
	info->icount.rx += num_bytes;

	memcpy(tty->flip.char_buf_ptr, dma_buffer, num_bytes);
	tty->flip.char_buf_ptr += num_bytes;
	tty->flip.count += num_bytes;
	memset(tty->flip.flag_buf_ptr, 0, num_bytes);
	tty->flip.flag_buf_ptr += num_bytes;

	if (num_bytes > 0) {
		tty->flip.flag_buf_ptr--;

		status &= (0x1c & info->read_status_mask);

		if (status & info->ignore_status_mask) {
			tty->flip.count--;
			tty->flip.char_buf_ptr--;
			tty->flip.flag_buf_ptr--;
		} else if (status & 0x10) {
			*tty->flip.flag_buf_ptr = TTY_BREAK;
			(info->icount.brk)++;
			if (info->flags & ASYNC_SAK)
				do_SAK(tty);
		} else if (status & 0x08) {
			*tty->flip.flag_buf_ptr = TTY_FRAME;
			(info->icount.frame)++;
		}
		else if (status & 0x04) {
			*tty->flip.flag_buf_ptr = TTY_PARITY;
			(info->icount.parity)++;
		}

		tty->flip.flag_buf_ptr++;
		
		queue_task(&tty->flip.tqueue, &tq_timer);
	}

	if (dma_bytes != num_bytes) {
		num_bytes = dma_bytes - num_bytes;
		dma_bytes = 0;
		receive_chars_dma(info, num_bytes);
	} else
		dma_bytes = 0;
}

static _INLINE_ void transmit_chars_pio(struct esp_struct *info,
					int space_avail)
{
	int i;
	struct esp_pio_buffer *pio_buf;

	pio_buf = get_pio_buffer();

	if (!pio_buf)
		return;

	while (space_avail && info->xmit_cnt) {
		if (info->xmit_tail + space_avail <= ESP_XMIT_SIZE) {
			memcpy(pio_buf->data,
			       &(info->xmit_buf[info->xmit_tail]),
			       space_avail);
		} else {
			i = ESP_XMIT_SIZE - info->xmit_tail;
			memcpy(pio_buf->data,
			       &(info->xmit_buf[info->xmit_tail]), i);
			memcpy(&(pio_buf->data[i]), info->xmit_buf,
			       space_avail - i);
		}

		info->xmit_cnt -= space_avail;
		info->xmit_tail = (info->xmit_tail + space_avail) &
			(ESP_XMIT_SIZE - 1);