3c505.c

GNU Mach 微内核源代码, 基于美国卡内基美隆大学的 Mach 研究项目

/*
 * Linux ethernet device driver for the 3Com Etherlink Plus (3C505)
 *      By Craig Southeren, Juha Laiho and Philip Blundell
 *
 * 3c505.c      This module implements an interface to the 3Com
 *              Etherlink Plus (3c505) ethernet card. Linux device 
 *              driver interface reverse engineered from the Linux 3C509
 *              device drivers. Some 3C505 information gleaned from
 *              the Crynwr packet driver. Still this driver would not
 *              be here without 3C505 technical reference provided by
 *              3Com.
 *
 * $Id: 3c505.c,v 1.1 1999/04/26 05:51:48 tb Exp $
 *
 * Authors:     Linux 3c505 device driver by
 *                      Craig Southeren, <[e-mail]>
 *              Final debugging by
 *                      Andrew Tridgell, <[e-mail]>
 *              Auto irq/address, tuning, cleanup and v1.1.4+ kernel mods by
 *                      Juha Laiho, <[e-mail]>
 *              Linux 3C509 driver by
 *                      Donald Becker, <[e-mail]>
 *              Crynwr packet driver by
 *                      Krishnan Gopalan and Gregg Stefancik,
 *                      Clemson University Engineering Computer Operations.
 *                      Portions of the code have been adapted from the 3c505
 *                         driver for NCSA Telnet by Bruce Orchard and later
 *                         modified by Warren Van Houten and [e-mail].
 *              3C505 technical information provided by
 *                      Terry Murphy, of 3Com Network Adapter Division
 *              Linux 1.3.0 changes by
 *                      Alan Cox <[e-mail]>
 *              More debugging and DMA version by Philip Blundell
 */

/* Theory of operation:

 * The 3c505 is quite an intelligent board.  All communication with it is done
 * by means of Primary Command Blocks (PCBs); these are transferred using PIO
 * through the command register.  The card has 256k of on-board RAM, which is
 * used to buffer received packets.  It might seem at first that more buffers
 * are better, but in fact this isn't true.  From my tests, it seems that
 * more than about 10 buffers are unnecessary, and there is a noticeable
 * performance hit in having more active on the card.  So the majority of the
 * card's memory isn't, in fact, used.
 *
 * We keep up to 4 "receive packet" commands active on the board at a time.
 * When a packet comes in, so long as there is a receive command active, the
 * board will send us a "packet received" PCB and then add the data for that
 * packet to the DMA queue.  If a DMA transfer is not already in progress, we
 * set one up to start uploading the data.  We have to maintain a list of
 * backlogged receive packets, because the card may decide to tell us about
 * a newly-arrived packet at any time, and we may not be able to start a DMA
 * transfer immediately (ie one may already be going on).  We can't NAK the
 * PCB, because then it would throw the packet away.
 *
 * Trying to send a PCB to the card at the wrong moment seems to have bad
 * effects.  If we send it a transmit PCB while a receive DMA is happening,
 * it will just NAK the PCB and so we will have wasted our time.  Worse, it
 * sometimes seems to interrupt the transfer.  The majority of the low-level
 * code is protected by one huge semaphore -- "busy" -- which is set whenever
 * it probably isn't safe to do anything to the card.  The receive routine
 * must gain a lock on "busy" before it can start a DMA transfer, and the
 * transmit routine must gain a lock before it sends the first PCB to the card.
 * The send_pcb() routine also has an internal semaphore to protect it against
 * being re-entered (which would be disastrous) -- this is needed because
 * several things can happen asynchronously (re-priming the receiver and
 * asking the card for statistics, for example).  send_pcb() will also refuse
 * to talk to the card at all if a DMA upload is happening.  The higher-level
 * networking code will reschedule a later retry if some part of the driver
 * is blocked.  In practice, this doesn't seem to happen very often.
 */

/* This driver will not work with revision 2 hardware, because the host
 * control register is write-only.  It should be fairly easy to arrange to
 * keep our own soft-copy of the intended contents of this register, if
 * somebody has the time.  There may be firmware differences that cause
 * other problems, though, and I don't have an old card to test.
 */

/* The driver is a mess.  I took Craig's and Juha's code, and hacked it firstly
 * to make it more reliable, and secondly to add DMA mode.  Many things could
 * probably be done better; the concurrency protection is particularly awful.
 */

#include <linux/module.h>

#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/string.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/in.h>
#include <linux/malloc.h>
#include <linux/ioport.h>
#include <asm/bitops.h>
#include <asm/io.h>
#include <asm/dma.h>

#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>

#include "3c505.h"

#define ELP_DMA      6		/* DMA channel to use */
#define ELP_RX_PCBS  4

/*********************************************************
 *
 *  define debug messages here as common strings to reduce space
 *
 *********************************************************/

static const char *filename = __FILE__;

static const char *timeout_msg = "*** timeout at %s:%s (line %d) ***\n";
#define TIMEOUT_MSG(lineno) \
	printk(timeout_msg, filename,__FUNCTION__,(lineno))

static const char *invalid_pcb_msg =
"*** invalid pcb length %d at %s:%s (line %d) ***\n";
#define INVALID_PCB_MSG(len) \
	printk(invalid_pcb_msg, (len),filename,__FUNCTION__,__LINE__)

static const char *search_msg = "%s: Looking for 3c505 adapter at address %#x...";

static const char *stilllooking_msg = "still looking...";

static const char *found_msg = "found.\n";

static const char *notfound_msg = "not found (reason = %d)\n";

static const char *couldnot_msg = "%s: 3c505 not found\n";

/*********************************************************
 *
 *  various other debug stuff
 *
 *********************************************************/

#ifdef ELP_DEBUG
static const int elp_debug = ELP_DEBUG;
#else
static const int elp_debug = 0;
#endif

/*
 *  0 = no messages (well, some)
 *  1 = messages when high level commands performed
 *  2 = messages when low level commands performed
 *  3 = messages when interrupts received
 */

/*****************************************************************
 *
 * useful macros
 *
 *****************************************************************/

#ifndef	TRUE
#define	TRUE	1
#endif

#ifndef	FALSE
#define	FALSE	0
#endif


/*****************************************************************
 *
 * List of I/O-addresses we try to auto-sense
 * Last element MUST BE 0!
 *****************************************************************/

const int addr_list[] = {0x300, 0x280, 0x310, 0};

/* Dma Memory related stuff */

/* Pure 2^n version of get_order */
static inline int __get_order(unsigned long size)
{
	int order;

	size = (size - 1) >> (PAGE_SHIFT - 1);
	order = -1;
	do {
		size >>= 1;
		order++;
	} while (size);
	return order;
}

static unsigned long dma_mem_alloc(int size)
{
	int order = __get_order(size);

	return __get_dma_pages(GFP_KERNEL, order);
}


/*****************************************************************
 *
 * Functions for I/O (note the inline !)
 *
 *****************************************************************/

static inline unsigned char inb_status(unsigned int base_addr)
{
	return inb(base_addr + PORT_STATUS);
}

static inline unsigned char inb_control(unsigned int base_addr)
{
	return inb(base_addr + PORT_CONTROL);
}

static inline int inb_command(unsigned int base_addr)
{
	return inb(base_addr + PORT_COMMAND);
}

static inline void outb_control(unsigned char val, unsigned int base_addr)
{
	outb(val, base_addr + PORT_CONTROL);
}

static inline void outb_command(unsigned char val, unsigned int base_addr)
{
	outb(val, base_addr + PORT_COMMAND);
}

static inline unsigned int inw_data(unsigned int base_addr)
{
	return inw(base_addr + PORT_DATA);
}

static inline void outw_data(unsigned int val, unsigned int base_addr)
{
	outw(val, base_addr + PORT_DATA);
}


/*****************************************************************
 *
 *  structure to hold context information for adapter
 *
 *****************************************************************/

#define DMA_BUFFER_SIZE  1600
#define BACKLOG_SIZE      4

typedef struct {
	volatile short got[NUM_TRANSMIT_CMDS];	/* flags for command completion */
	pcb_struct tx_pcb;	/* PCB for foreground sending */
	pcb_struct rx_pcb;	/* PCB for foreground receiving */
	pcb_struct itx_pcb;	/* PCB for background sending */
	pcb_struct irx_pcb;	/* PCB for background receiving */
	struct enet_statistics stats;

	void *dma_buffer;

	struct {
		unsigned int length[BACKLOG_SIZE];
		unsigned int in;
		unsigned int out;
	} rx_backlog;

	struct {
		unsigned int direction;
		unsigned int length;
		unsigned int copy_flag;
		struct sk_buff *skb;
		long int start_time;
	} current_dma;

	/* flags */
	unsigned long send_pcb_semaphore;
	unsigned int dmaing;
	unsigned long busy;

	unsigned int rx_active;  /* number of receive PCBs */
} elp_device;

static inline unsigned int backlog_next(unsigned int n)
{
	return (n + 1) % BACKLOG_SIZE;
}

/*****************************************************************
 *
 *  useful functions for accessing the adapter
 *
 *****************************************************************/

/*
 * use this routine when accessing the ASF bits as they are
 * changed asynchronously by the adapter
 */

/* get adapter PCB status */
#define	GET_ASF(addr) \
	(get_status(addr)&ASF_PCB_MASK)

static inline int get_status(unsigned int base_addr)
{
	int timeout = jiffies + 10;
	register int stat1;
	do {
		stat1 = inb_status(base_addr);
	} while (stat1 != inb_status(base_addr) && jiffies < timeout);
	if (jiffies >= timeout)
		TIMEOUT_MSG(__LINE__);
	return stat1;
}

static inline void set_hsf(unsigned int base_addr, int hsf)
{
	cli();
	outb_control((inb_control(base_addr) & ~HSF_PCB_MASK) | hsf, base_addr);
	sti();
}

static int start_receive(struct device *, pcb_struct *);

inline static void adapter_reset(struct device *dev)
{
	int timeout;
	unsigned char orig_hcr = inb_control(dev->base_addr);

	elp_device *adapter = dev->priv;

	outb_control(0, dev->base_addr);

	if (inb_status(dev->base_addr) & ACRF) {
		do {
			inb_command(dev->base_addr);
			timeout = jiffies + 2;
			while ((jiffies <= timeout) && !(inb_status(dev->base_addr) & ACRF));
		} while (inb_status(dev->base_addr) & ACRF);
		set_hsf(dev->base_addr, HSF_PCB_NAK);
	}
	outb_control(inb_control(dev->base_addr) | ATTN | DIR, dev->base_addr);
	timeout = jiffies + 1;
	while (jiffies <= timeout);
	outb_control(inb_control(dev->base_addr) & ~ATTN, dev->base_addr);
	timeout = jiffies + 1;
	while (jiffies <= timeout);
	outb_control(inb_control(dev->base_addr) | FLSH, dev->base_addr);
	timeout = jiffies + 1;
	while (jiffies <= timeout);
	outb_control(inb_control(dev->base_addr) & ~FLSH, dev->base_addr);
	timeout = jiffies + 1;
	while (jiffies <= timeout);

	outb_control(orig_hcr, dev->base_addr);
	if (!start_receive(dev, &adapter->tx_pcb))
		printk("%s: start receive command failed \n", dev->name);
}

/* Check to make sure that a DMA transfer hasn't timed out.  This should never happen
 * in theory, but seems to occur occasionally if the card gets prodded at the wrong
 * time.
 */
static inline void check_dma(struct device *dev)
{
	elp_device *adapter = dev->priv;
	if (adapter->dmaing && (jiffies > (adapter->current_dma.start_time + 10))) {
		unsigned long flags;
		printk("%s: DMA %s timed out, %d bytes left\n", dev->name, adapter->current_dma.direction ? "download" : "upload", get_dma_residue(dev->dma));
		save_flags(flags);
		cli();
		adapter->dmaing = 0;
		adapter->busy = 0;
		disable_dma(dev->dma);
		if (adapter->rx_active)
			adapter->rx_active--;
		outb_control(inb_control(dev->base_addr) & ~(DMAE | TCEN | DIR), dev->base_addr);
		restore_flags(flags);
	}
}

/* Primitive functions used by send_pcb() */
static inline unsigned int send_pcb_slow(unsigned int base_addr, unsigned char byte)
{
	unsigned int timeout;
	outb_command(byte, base_addr);
	for (timeout = jiffies + 5; jiffies < timeout;) {
		if (inb_status(base_addr) & HCRE)
			return FALSE;
	}
	printk("3c505: send_pcb_slow timed out\n");
	return TRUE;
}

static inline unsigned int send_pcb_fast(unsigned int base_addr, unsigned char byte)
{
	unsigned int timeout;
	outb_command(byte, base_addr);
	for (timeout = 0; timeout < 40000; timeout++) {
		if (inb_status(base_addr) & HCRE)
			return FALSE;
	}
	printk("3c505: send_pcb_fast timed out\n");
	return TRUE;
}

/* Check to see if the receiver needs restarting, and kick it if so */
static inline void prime_rx(struct device *dev)
{
	elp_device *adapter = dev->priv;
	while (adapter->rx_active < ELP_RX_PCBS && dev->start) {
		if (!start_receive(dev, &adapter->itx_pcb))
			break;
	}
}

/*****************************************************************
 *
 * send_pcb
 *   Send a PCB to the adapter. 
 *
 *	output byte to command reg  --<--+
 *	wait until HCRE is non zero      |
 *	loop until all bytes sent   -->--+
 *	set HSF1 and HSF2 to 1
 *	output pcb length
 *	wait until ASF give ACK or NAK
 *	set HSF1 and HSF2 to 0
 *
 *****************************************************************/

/* This can be quite slow -- the adapter is allowed to take up to 40ms