/* atp.c: Attached (pocket) ethernet adaptor driver for linux. */
/*
	Written 1993 by Donald Becker.
	Copyright 1993 United States Government as represented by the Director,
	National Security Agency.  This software may only be used and distributed
	according to the terms of the GNU Public License as modified by SRC,
	incorported herein by reference.

	The author may be reached as becker@super.org or
	C/O Supercomputing Research Ctr., 17100 Science Dr., Bowie MD 20715

*/

static char *version =
	"atp.c:v0.04 2/25/94 Donald Becker (becker@super.org)\n";

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

					Theory of Operation
	
	The RTL8002 adaptor 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 adaptor 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.

	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 adaptor, 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 overriden 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/config.h>		/* Used only to override default values. */
#include <linux/kernel.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 <errno.h>

#include "dev.h"
#include "eth.h"
#include "skbuff.h"
#include "arp.h"

#include "atp.h"

/* Compatibility definitions for earlier kernel versions. */
#ifndef HAVE_AUTOIRQ
/* From auto_irq.c, in ioport.h for later versions. */
extern void autoirq_setup(int waittime);
extern int autoirq_report(int waittime);
/* The map from IRQ number (as passed to the interrupt handler) to
   'struct device'. */
extern struct device *irq2dev_map[16];
#endif

#ifndef HAVE_ALLOC_SKB
#define alloc_skb(size, priority) (struct sk_buff *) kmalloc(size,priority)
#define kfree_skbmem(addr, size) kfree_s(addr,size);
#endif

#ifndef HAVE_PORTRESERVE
#define check_region(ioaddr, size)		0
#define snarf_region(ioaddr, size);		do ; while (0)
#endif

/* use 0 for production, 1 for verification, >2 for debug */
#ifndef NET_DEBUG
#define NET_DEBUG 4
#endif
static unsigned int net_debug = NET_DEBUG;

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

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

extern int atp_probe(struct device *dev);

static int atp_probe1(struct device *dev, short ioaddr);
static void init_dev(struct device *dev);
static void get_node_ID(struct device *dev);
static unsigned short eeprom_op(short ioaddr, unsigned int cmd);
static int net_open(struct device *dev);
static void hardware_init(struct device *dev);
static void write_packet(short ioaddr, int length, unsigned char *packet, int mode);
static void trigger_send(short ioaddr, int length);
static int	net_send_packet(struct sk_buff *skb, struct device *dev);
static void net_interrupt(int reg_ptr);
static void net_rx(struct device *dev);
static void read_block(short ioaddr, int length, unsigned char *buffer, int data_mode);
static int net_close(struct device *dev);
static struct enet_statistics *net_get_stats(struct device *dev);
#ifdef HAVE_MULTICAST
static void set_multicast_list(struct device *dev, int num_addrs, void *addrs);
#endif


/* Check for a network adaptor 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, alloate space for the device and return success
   (detachable devices only).
   */
int
atp_init(struct device *dev)
{
	int *port, ports[] = {0x378, 0x278, 0x3bc, 0};
	int base_addr = dev->base_addr;

	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++) {
		int 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 atp_probe1(struct device *dev, short ioaddr)
{
	int saved_ctrl_reg, status;

	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);
	/* IRQEN=0, SLCTB=high INITB=high, AUTOFDB=high, STBB=high. */
	outb(0x04, ioaddr + PAR_CONTROL);
	write_reg_high(ioaddr, CMR1, CMR1h_RESET);
	eeprom_delay(2048);
	status = read_nibble(ioaddr, CMR1);

	if ((status & 0x78) != 0x08) {
		/* The pocket adaptor probe failed, restore the control register. */
		outb(saved_ctrl_reg, ioaddr + PAR_CONTROL);
		return 1;
	}
	status = read_nibble(ioaddr, CMR2_h);
	if ((status & 0x78) != 0x10) {
		outb(saved_ctrl_reg, ioaddr + PAR_CONTROL);
		return 1;
	}
	/* 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 (ioaddr == 0x378)
		dev->irq = 7;
	else
		dev->irq = 5;
	write_reg_high(ioaddr, CMR1, CMR1h_TxRxOFF); /* Diable Tx and Rx units. */
	write_reg(ioaddr, CMR2, CMR2_NULL);

	dev->base_addr = ioaddr;

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

	printk("%s: Pocket adaptor found at %#3x, IRQ %d, SAPROM "
		   "%02X:%02X:%02X:%02X:%02X:%02X.\n", dev->name, dev->base_addr,
		   dev->irq, dev->dev_addr[0], dev->dev_addr[1], dev->dev_addr[2],
		   dev->dev_addr[3], dev->dev_addr[4], dev->dev_addr[5]);

	/* Leave the hardware in a reset state. */
    write_reg_high(ioaddr, CMR1, CMR1h_RESET);

	if (net_debug)
		printk(version);

	/* Initialize the device structure. */
	init_dev(dev);
	dev->priv = kmalloc(sizeof(struct net_local), GFP_KERNEL);
	memset(dev->priv, 0, sizeof(struct net_local));


	{
		struct net_local *lp = (struct net_local *)dev->priv;
		lp->addr_mode = CMR2h_Normal;
	}

	/* For the ATP adaptor the "if_port" is really the data transfer mode. */
	dev->if_port = (dev->mem_start & 0xf) ? dev->mem_start & 0x7 : 4;
	if (dev->mem_end & 0xf)
		net_debug = dev->mem_end & 7;

	dev->open		= net_open;
	dev->stop		= net_close;
	dev->hard_start_xmit = net_send_packet;
	dev->get_stats	= net_get_stats;
#ifdef HAVE_MULTICAST
	dev->set_multicast_list = &set_multicast_list;
#endif

	return 0;
}

/* Fill in the fields of the device structure with ethernet-generic values.
   This should be in a common file instead of per-driver.  */
static void init_dev(struct device *dev)
{
	int i;

	for (i = 0; i < DEV_NUMBUFFS; i++)
		dev->buffs[i] = NULL;

	dev->hard_header	= eth_header;
	dev->add_arp		= eth_add_arp;
	dev->queue_xmit		= dev_queue_xmit;
	dev->rebuild_header = eth_rebuild_header;
	dev->type_trans		= eth_type_trans;

	dev->type			= ARPHRD_ETHER;
	dev->hard_header_len = ETH_HLEN;
	dev->mtu			= 1500; /* eth_mtu */
	dev->addr_len		= ETH_ALEN;
	for (i = 0; i < ETH_ALEN; i++) {
		dev->broadcast[i]=0xff;
	}

	/* New-style flags. */
	dev->flags			= IFF_BROADCAST;
	dev->family			= AF_INET;
	dev->pa_addr		= 0;
	dev->pa_brdaddr		= 0;
	dev->pa_mask		= 0;
	dev->pa_alen		= sizeof(unsigned long);
}

/* Read the station address PROM, usually a word-wide EEPROM. */
static void get_node_ID(struct device *dev)
{
	short ioaddr = dev->base_addr;
	int sa_offset = 0;
	int i;
	
	write_reg(ioaddr, CMR2, CMR2_EEPROM);	  /* Point to the EEPROM control registers. */
	
	/* Some adaptors have the station address at offset 15 instead of offset
	   zero.  Check for it, and fix it if needed. */
	if (eeprom_op(ioaddr, EE_READ(0)) == 0xffff)
		sa_offset = 15;
	
	for (i = 0; i < 3; i++)
		((unsigned short *)dev->dev_addr)[i] =
			ntohs(eeprom_op(ioaddr, EE_READ(sa_offset + i)));
	
	write_reg(ioaddr, CMR2, CMR2_NULL);
}

/*
  An EEPROM read command starts by shifting out 0x60+address, and then
  shifting in the serial data. See the NatSemi databook for details.
 *		   ________________
 * CS : __|
 *			   ___	   ___
 * CLK: ______|	  |___|	  |
 *		 __ _______ _______
 * DI :	 __X_______X_______X
 * DO :	 _________X_______X
 */

static unsigned short eeprom_op(short ioaddr, unsigned int cmd)
{
	unsigned eedata_out = 0;
	int num_bits = EE_CMD_SIZE;
	
	while (--num_bits >= 0) {
		char outval = test_bit(num_bits, &cmd) ? EE_DATA_WRITE : 0;
		write_reg_high(ioaddr, PROM_CMD, outval | EE_CLK_LOW);
		eeprom_delay(5);
		write_reg_high(ioaddr, PROM_CMD, outval | EE_CLK_HIGH);
		eedata_out <<= 1;
		if (read_nibble(ioaddr, PROM_DATA) & EE_DATA_READ)
			eedata_out++;
		eeprom_delay(5);
	}
	write_reg_high(ioaddr, PROM_CMD, EE_CLK_LOW & ~EE_CS);
	return eedata_out;
}


/* Open/initialize the board.  This is called (in the current kernel)
   sometime after booting when the 'ifconfig' program is run.

   This routine sets everything up anew at each open, even
   registers that "should" only need to be set once at boot, so that
   there is non-reboot way to recover if something goes wrong.

   This is an attachable device: if there is no dev->priv entry then it wasn't
   probed for at boot-time, and we need to probe for it again.
   */
static int net_open(struct device *dev)
{

	/* The interrupt line is turned off (tri-stated) when the device isn't in
	   use.  That's especially important for "attached" interfaces where the
	   port or interrupt may be shared. */
	if (irq2dev_map[dev->irq] != 0
		|| (irq2dev_map[dev->irq] = dev) == 0
		|| request_irq(dev->irq, &net_interrupt)) {
		return -EAGAIN;
	}

	hardware_init(dev);
	dev->start = 1;
	return 0;
}

/* This routine resets the hardware.  We initialize everything, assuming that
   the hardware may have been temporarily detacted. */
static void hardware_init(struct device *dev)
{
	struct net_local *lp = (struct net_local *)dev->priv;
	int ioaddr = dev->base_addr;
    int i;

	write_reg_high(ioaddr, CMR1, CMR1h_RESET);
	
    for (i = 0; i < 6; i++)
		write_reg_byte(ioaddr, PAR0 + i, dev->dev_addr[i]);

	write_reg_high(ioaddr, CMR2, lp->addr_mode);

	if (net_debug > 2) {
		printk("%s: Reset: current Rx mode %d.\n", dev->name,
			   (read_nibble(ioaddr, CMR2_h) >> 3) & 0x0f);
	}

    write_reg(ioaddr, CMR2, CMR2_IRQOUT);
    write_reg_high(ioaddr, CMR1, CMR1h_RxENABLE | CMR1h_TxENABLE);

	/* Enable the interrupt line from the serial port. */
	outb(Ctrl_SelData + Ctrl_IRQEN, ioaddr + PAR_CONTROL);

	/* Unmask the interesting interrupts. */