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      1 /*	$NetBSD: if_sn.c,v 1.47 2007/10/17 19:55:13 garbled Exp $	*/
      2 
      3 /*
      4  * National Semiconductor  DP8393X SONIC Driver
      5  * Copyright (c) 1991   Algorithmics Ltd (http://www.algor.co.uk)
      6  * You may use, copy, and modify this program so long as you retain the
      7  * copyright line.
      8  *
      9  * This driver has been substantially modified since Algorithmics donated
     10  * it.
     11  *
     12  *   Denton Gentry <denny1 (at) home.com>
     13  * and also
     14  *   Yanagisawa Takeshi <yanagisw (at) aa.ap.titech.ac.jp>
     15  * did the work to get this running on the Macintosh.
     16  */
     17 
     18 #include <sys/cdefs.h>
     19 __KERNEL_RCSID(0, "$NetBSD: if_sn.c,v 1.47 2007/10/17 19:55:13 garbled Exp $");
     20 
     21 #include <sys/param.h>
     22 #include <sys/systm.h>
     23 
     24 #include <net/if.h>
     25 #include <net/if_ether.h>
     26 
     27 #include <machine/bus.h>
     28 
     29 #include <mac68k/dev/if_snvar.h>
     30 
     31 static const uint8_t bbr4[] = {0,8,4,12,2,10,6,14,1,9,5,13,3,11,7,15};
     32 #define bbr(v)	((bbr4[(v) & 0xf] << 4) | bbr4[((v) >> 4) & 0xf])
     33 
     34 void
     35 sn_get_enaddr(bus_space_tag_t t, bus_space_handle_t h, bus_size_t o,
     36     uint8_t *dst)
     37 {
     38 	int i, do_bbr;
     39 	uint8_t b;
     40 
     41 	/*
     42 	 * For reasons known only to Apple, MAC addresses in the ethernet
     43 	 * PROM are stored in Token Ring (IEEE 802.5) format, that is
     44 	 * with all of the bits in each byte reversed (canonical bit format).
     45 	 * When the address is read out it must be reversed to ethernet format
     46 	 * before use.
     47 	 *
     48 	 * Apple has been assigned OUI's 08:00:07 and 00:a0:40. All onboard
     49 	 * ethernet addresses on 68K machines should be in one of these
     50 	 * two ranges.
     51 	 *
     52 	 * Here is where it gets complicated.
     53 	 *
     54 	 * The PMac 7200, 7500, 8500, and 9500 accidentally had the PROM
     55 	 * written in standard ethernet format. The MacOS accounted for this
     56 	 * in these systems, and did not reverse the bytes. Some other
     57 	 * networking utilities were not so forgiving, and got confused.
     58 	 * "Some" of Apple's Nubus ethernet cards also had their bits
     59 	 * burned in ethernet format.
     60 	 *
     61 	 * Apple petitioned the IEEE and was granted the 00:05:02 (bit reversal
     62 	 * of 00:a0:40) as well. As of OpenTransport 1.1.1, Apple removed
     63 	 * their workaround and now reverses the bits regardless of
     64 	 * what kind of machine it is. So PMac systems and the affected
     65 	 * Nubus cards now use 00:05:02, instead of the 00:a0:40 for which they
     66 	 * were intended.
     67 	 *
     68 	 * See Apple Techinfo article TECHINFO-0020552, "OpenTransport 1.1.1
     69 	 * and MacOS System 7.5.3 FAQ (10/96)" for more details.
     70 	 */
     71 	do_bbr = 0;
     72 	b = bus_space_read_1(t, h, o);
     73 	if (b == 0x10)
     74 		do_bbr = 1;
     75 	dst[0] = (do_bbr) ? bbr(b) : b;
     76 
     77 	for (i = 1 ; i < ETHER_ADDR_LEN ; i++) {
     78 		b = bus_space_read_1(t, h, o + i);
     79 		dst[i] = (do_bbr) ? bbr(b) : b;
     80 	}
     81 }
     82