atp.c

讲述linux的初始化过程

/* atp.c: Attached (pocket) ethernet adapter driver for linux. */
/*
	This is a driver for commonly OEM pocket (parallel port)
	ethernet adapters based on the Realtek RTL8002 and RTL8012 chips.

	Written 1993-2000 by Donald Becker.

	This software may be used and distributed according to the terms of
	the GNU General Public License (GPL), incorporated herein by reference.
	Drivers based on or derived from this code fall under the GPL and must
	retain the authorship, copyright and license notice.  This file is not
	a complete program and may only be used when the entire operating
	system is licensed under the GPL.

	Copyright 1993 United States Government as represented by the Director,
	National Security Agency.  Copyright 1994-2000 retained by the original
	author, Donald Becker. The timer-based reset code was supplied in 1995
	by Bill Carlson, [e-mail].

	The author may be reached as [e-mail], or C/O
	Scyld Computing Corporation
	410 Severn Ave., Suite 210
	Annapolis MD 21403

	Support information and updates available at
	http://www.scyld.com/network/atp.html


	Modular support/softnet added by Alan Cox.

*/

static const char versionA[] =
"atp.c:v1.09 8/9/2000 Donald Becker <[e-mail]>\n";
static const char versionB[] =
"  http://www.scyld.com/network/atp.html\n";

/* The user-configurable values.
   These may be modified when a driver module is loaded.*/

static int debug = 1; 			/* 1 normal messages, 0 quiet .. 7 verbose. */
#define net_debug debug

/* Maximum events (Rx packets, etc.) to handle at each interrupt. */
static int max_interrupt_work = 15;

#define NUM_UNITS 2
/* The standard set of ISA module parameters. */
static int io[NUM_UNITS];
static int irq[NUM_UNITS];
static int xcvr[NUM_UNITS]; 			/* The data transfer mode. */

/* Operational parameters that are set at compile time. */

/* Time in jiffies before concluding the transmitter is hung. */
#define TX_TIMEOUT  (400*HZ/1000)

/*
	This file is a device driver for the RealTek (aka AT-Lan-Tec) pocket
	ethernet adapter.  This is a common low-cost OEM pocket ethernet
	adapter, sold under many names.

  Sources:
	This driver was written from the packet driver assembly code provided by
	Vincent Bono of AT-Lan-Tec.	 Ever try to figure out how a complicated
	device works just from the assembly code?  It ain't pretty.  The following
	description is written based on guesses and writing lots of special-purpose
	code to test my theorized operation.

	In 1997 Realtek made available the documentation for the second generation
	RTL8012 chip, which has lead to several driver improvements.
	  http://www.realtek.com.tw/cn/cn.html

					Theory of Operation

	The RTL8002 adapter seems to be built around a custom spin of the SEEQ
	controller core.  It probably has a 16K or 64K internal packet buffer, of
	which the first 4K is devoted to transmit and the rest to receive.
	The controller maintains the queue of received packet and the packet buffer
	access pointer internally, with only 'reset to beginning' and 'skip to next
	packet' commands visible.  The transmit packet queue holds two (or more?)
	packets: both 'retransmit this packet' (due to collision) and 'transmit next
	packet' commands must be started by hand.

	The station address is stored in a standard bit-serial EEPROM which must be
	read (ughh) by the device driver.  (Provisions have been made for
	substituting a 74S288 PROM, but I haven't gotten reports of any models
	using it.)  Unlike built-in devices, a pocket adapter can temporarily lose
	power without indication to the device driver.  The major effect is that
	the station address, receive filter (promiscuous, etc.) and transceiver
	must be reset.

	The controller itself has 16 registers, some of which use only the lower
	bits.  The registers are read and written 4 bits at a time.  The four bit
	register address is presented on the data lines along with a few additional
	timing and control bits.  The data is then read from status port or written
	to the data port.

	Correction: the controller has two banks of 16 registers.  The second
	bank contains only the multicast filter table (now used) and the EEPROM
	access registers.

	Since the bulk data transfer of the actual packets through the slow
	parallel port dominates the driver's running time, four distinct data
	(non-register) transfer modes are provided by the adapter, two in each
	direction.  In the first mode timing for the nibble transfers is
	provided through the data port.  In the second mode the same timing is
	provided through the control port.  In either case the data is read from
	the status port and written to the data port, just as it is accessing
	registers.

	In addition to the basic data transfer methods, several more are modes are
	created by adding some delay by doing multiple reads of the data to allow
	it to stabilize.  This delay seems to be needed on most machines.

	The data transfer mode is stored in the 'dev->if_port' field.  Its default
	value is '4'.  It may be overridden at boot-time using the third parameter
	to the "ether=..." initialization.

	The header file <atp.h> provides inline functions that encapsulate the
	register and data access methods.  These functions are hand-tuned to
	generate reasonable object code.  This header file also documents my
	interpretations of the device registers.
*/

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

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

#include "atp.h"

MODULE_AUTHOR("Donald Becker <[e-mail]>");
MODULE_DESCRIPTION("RealTek RTL8002/8012 parallel port Ethernet driver");
MODULE_PARM(max_interrupt_work, "i");
MODULE_PARM(debug, "i");
MODULE_PARM(io, "1-" __MODULE_STRING(MAX_UNITS) "i");
MODULE_PARM(irq, "1-" __MODULE_STRING(MAX_UNITS) "i");
MODULE_PARM(xcvr, "1-" __MODULE_STRING(MAX_UNITS) "i");

#define RUN_AT(x) (jiffies + (x))

/* The number of low I/O ports used by the ethercard. */
#define ETHERCARD_TOTAL_SIZE	3

/* Sequence to switch an 8012 from printer mux to ethernet mode. */
static char mux_8012[] = { 0xff, 0xf7, 0xff, 0xfb, 0xf3, 0xfb, 0xff, 0xf7,};

struct net_local {
    spinlock_t lock;
    struct net_device *next_module;
    struct net_device_stats stats;
    struct timer_list timer;	/* Media selection timer. */
    long last_rx_time;		/* Last Rx, in jiffies, to handle Rx hang. */
    int saved_tx_size;
    unsigned int tx_unit_busy:1;
    unsigned char re_tx,	/* Number of packet retransmissions. */
		addr_mode,		/* Current Rx filter e.g. promiscuous, etc. */
		pac_cnt_in_tx_buf,
		chip_type;
};

/* This code, written by [e-mail], resets the adapter every
   TIMED_CHECKER ticks.  This recovers from an unknown error which
   hangs the device. */
#define TIMED_CHECKER (HZ/4)
#ifdef TIMED_CHECKER
#include <linux/timer.h>
static void atp_timed_checker(unsigned long ignored);
#endif

/* Index to functions, as function prototypes. */

static int atp_probe1(struct net_device *dev, long ioaddr);
static void get_node_ID(struct net_device *dev);
static unsigned short eeprom_op(long ioaddr, unsigned int cmd);
static int net_open(struct net_device *dev);
static void hardware_init(struct net_device *dev);
static void write_packet(long ioaddr, int length, unsigned char *packet, int mode);
static void trigger_send(long ioaddr, int length);
static int	atp_send_packet(struct sk_buff *skb, struct net_device *dev);
static void atp_interrupt(int irq, void *dev_id, struct pt_regs *regs);
static void net_rx(struct net_device *dev);
static void read_block(long ioaddr, int length, unsigned char *buffer, int data_mode);
static int net_close(struct net_device *dev);
static struct net_device_stats *net_get_stats(struct net_device *dev);
static void set_rx_mode_8002(struct net_device *dev);
static void set_rx_mode_8012(struct net_device *dev);
static void tx_timeout(struct net_device *dev);


/* A list of all installed ATP devices, for removing the driver module. */
static struct net_device *root_atp_dev = NULL;

/* Check for a network adapter of this type, and return '0' iff one exists.
   If dev->base_addr == 0, probe all likely locations.
   If dev->base_addr == 1, always return failure.
   If dev->base_addr == 2, allocate space for the device and return success
   (detachable devices only).
   */
static int __init atp_init(struct net_device *dev)
{
	int *port, ports[] = {0x378, 0x278, 0x3bc, 0};
	int base_addr = dev ? dev->base_addr : io[0];

	if (base_addr > 0x1ff)		/* Check a single specified location. */
		return atp_probe1(dev, base_addr);
	else if (base_addr == 1)	/* Don't probe at all. */
		return -ENXIO;

	for (port = ports; *port; port++) {
		long ioaddr = *port;
		outb(0x57, ioaddr + PAR_DATA);
		if (inb(ioaddr + PAR_DATA) != 0x57)
			continue;
		if (atp_probe1(dev, ioaddr) == 0)
			return 0;
	}

	return -ENODEV;
}

static int __init atp_probe1(struct net_device *dev, long ioaddr)
{
	struct net_local *lp;
	int saved_ctrl_reg, status, i;

	outb(0xff, ioaddr + PAR_DATA);
	/* Save the original value of the Control register, in case we guessed
	   wrong. */
	saved_ctrl_reg = inb(ioaddr + PAR_CONTROL);
	if (net_debug > 3)
		printk("atp: Control register was %#2.2x.\n", saved_ctrl_reg);
	/* IRQEN=0, SLCTB=high INITB=high, AUTOFDB=high, STBB=high. */
	outb(0x04, ioaddr + PAR_CONTROL);
#ifndef final_version
	if (net_debug > 3) {
		/* Turn off the printer multiplexer on the 8012. */
		for (i = 0; i < 8; i++)
			outb(mux_8012[i], ioaddr + PAR_DATA);
		write_reg(ioaddr, MODSEL, 0x00);
		printk("atp: Registers are ");
		for (i = 0; i < 32; i++)
			printk(" %2.2x", read_nibble(ioaddr, i));
		printk(".\n");
	}
#endif
	/* Turn off the printer multiplexer on the 8012. */
	for (i = 0; i < 8; i++)
		outb(mux_8012[i], ioaddr + PAR_DATA);
	write_reg_high(ioaddr, CMR1, CMR1h_RESET);
	/* udelay() here? */
	status = read_nibble(ioaddr, CMR1);

	if (net_debug > 3) {
		printk(KERN_DEBUG "atp: Status nibble was %#2.2x..", status);
		for (i = 0; i < 32; i++)
			printk(" %2.2x", read_nibble(ioaddr, i));
		printk("\n");
	}

	if ((status & 0x78) != 0x08) {
		/* The pocket adapter probe failed, restore the control register. */
		outb(saved_ctrl_reg, ioaddr + PAR_CONTROL);
		return -ENODEV;
	}
	status = read_nibble(ioaddr, CMR2_h);
	if ((status & 0x78) != 0x10) {
		outb(saved_ctrl_reg, ioaddr + PAR_CONTROL);
		return -ENODEV;
	}

	dev = init_etherdev(dev, sizeof(struct net_local));
	if (!dev)
		return -ENOMEM;
	SET_MODULE_OWNER(dev);

	/* Find the IRQ used by triggering an interrupt. */
	write_reg_byte(ioaddr, CMR2, 0x01);			/* No accept mode, IRQ out. */
	write_reg_high(ioaddr, CMR1, CMR1h_RxENABLE | CMR1h_TxENABLE);	/* Enable Tx and Rx. */

	/* Omit autoIRQ routine for now. Use "table lookup" instead.  Uhgggh. */
	if (irq[0])
		dev->irq = irq[0];
	else if (ioaddr == 0x378)
		dev->irq = 7;
	else
		dev->irq = 5;
	write_reg_high(ioaddr, CMR1, CMR1h_TxRxOFF); /* Disable Tx and Rx units. */
	write_reg(ioaddr, CMR2, CMR2_NULL);

	dev->base_addr = ioaddr;

	/* Read the station address PROM.  */
	get_node_ID(dev);

#ifndef MODULE
	if (net_debug)