/* 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, [email protected]. The author may be reached as [email protected], 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. _bit abuse fixed up by Alan Cox */ static const char version[] = …; /* The user-configurable values. These may be modified when a driver module is loaded.*/ static int debug = …; /* 1 normal messages, 0 quiet .. 7 verbose. */ #define net_debug … /* Maximum events (Rx packets, etc.) to handle at each interrupt. */ static int max_interrupt_work = …; #define NUM_UNITS … /* 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 … /* 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/ 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/types.h> #include <linux/fcntl.h> #include <linux/interrupt.h> #include <linux/ioport.h> #include <linux/in.h> #include <linux/string.h> #include <linux/errno.h> #include <linux/init.h> #include <linux/crc32.h> #include <linux/netdevice.h> #include <linux/etherdevice.h> #include <linux/skbuff.h> #include <linux/spinlock.h> #include <linux/delay.h> #include <linux/bitops.h> #include <asm/io.h> #include <asm/dma.h> #include "atp.h" MODULE_AUTHOR(…) …; MODULE_DESCRIPTION(…) …; MODULE_LICENSE(…) …; module_param(max_interrupt_work, int, 0); module_param(debug, int, 0); module_param_hw_array(io, int, ioport, NULL, 0); module_param_hw_array(irq, int, irq, NULL, 0); module_param_array(…); MODULE_PARM_DESC(…) …; MODULE_PARM_DESC(…) …; MODULE_PARM_DESC(…) …; MODULE_PARM_DESC(…) …; MODULE_PARM_DESC(…) …; /* The number of low I/O ports used by the ethercard. */ #define ETHERCARD_TOTAL_SIZE … /* Sequence to switch an 8012 from printer mux to ethernet mode. */ static char mux_8012[] = …; struct net_local { … }; /* This code, written by [email protected], resets the adapter every TIMED_CHECKER ticks. This recovers from an unknown error which hangs the device. */ #define TIMED_CHECKER … #ifdef TIMED_CHECKER #include <linux/timer.h> static void atp_timed_checker(struct timer_list *t); #endif /* Index to functions, as function prototypes. */ static int atp_probe1(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 pad, int mode); static void trigger_send(long ioaddr, int length); static netdev_tx_t atp_send_packet(struct sk_buff *skb, struct net_device *dev); static irqreturn_t atp_interrupt(int irq, void *dev_id); 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 void set_rx_mode(struct net_device *dev); static void tx_timeout(struct net_device *dev, unsigned int txqueue); /* A list of all installed ATP devices, for removing the driver module. */ static struct net_device *root_atp_dev; /* 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). FIXME: we should use the parport layer for this */ static int __init atp_init(void) { … } static const struct net_device_ops atp_netdev_ops = …; static int __init atp_probe1(long ioaddr) { … } /* Read the station address PROM, usually a word-wide EEPROM. */ static void __init get_node_ID(struct net_device *dev) { … } /* 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 __init eeprom_op(long ioaddr, u32 cmd) { … } /* 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 private entry then it wasn't probed for at boot-time, and we need to probe for it again. */ static int net_open(struct net_device *dev) { … } /* This routine resets the hardware. We initialize everything, assuming that the hardware may have been temporarily detached. */ static void hardware_init(struct net_device *dev) { … } static void trigger_send(long ioaddr, int length) { … } static void write_packet(long ioaddr, int length, unsigned char *packet, int pad_len, int data_mode) { … } static void tx_timeout(struct net_device *dev, unsigned int txqueue) { … } static netdev_tx_t atp_send_packet(struct sk_buff *skb, struct net_device *dev) { … } /* The typical workload of the driver: Handle the network interface interrupts. */ static irqreturn_t atp_interrupt(int irq, void *dev_instance) { … } #ifdef TIMED_CHECKER /* This following code fixes a rare (and very difficult to track down) problem where the adapter forgets its ethernet address. */ static void atp_timed_checker(struct timer_list *t) { … } #endif /* We have a good packet(s), get it/them out of the buffers. */ static void net_rx(struct net_device *dev) { … } static void read_block(long ioaddr, int length, unsigned char *p, int data_mode) { … } /* The inverse routine to net_open(). */ static int net_close(struct net_device *dev) { … } /* * Set or clear the multicast filter for this adapter. */ static void set_rx_mode(struct net_device *dev) { … } static int __init atp_init_module(void) { … } static void __exit atp_cleanup_module(void) { … } module_init(…) …; module_exit(atp_cleanup_module);
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