drivers/media/pci/ttpci/ttpci-eeprom.c

   1 /*
   2     Retrieve encoded MAC address from 24C16 serial 2-wire EEPROM,
   3     decode it and store it in the associated adapter struct for
   4     use by dvb_net.c
   5
   6     This card appear to have the 24C16 write protect held to ground,
   7     thus permitting normal read/write operation. Theoretically it
   8     would be possible to write routines to burn a different (encoded)
   9     MAC address into the EEPROM.
  10
  11     Robert Schlabbach   GMX
  12     Michael Glaum       KVH Industries
  13     Holger Waechtler    Convergence
  14
  15     Copyright (C) 2002-2003 Ralph Metzler <rjkm@metzlerbros.de>
  16                             Metzler Brothers Systementwicklung GbR
  17
  18     This program is free software; you can redistribute it and/or modify
  19     it under the terms of the GNU General Public License as published by
  20     the Free Software Foundation; either version 2 of the License, or
  21     (at your option) any later version.
  22
  23     This program is distributed in the hope that it will be useful,
  24     but WITHOUT ANY WARRANTY; without even the implied warranty of
  25     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  26     GNU General Public License for more details.
  27
  28     You should have received a copy of the GNU General Public License
  29     along with this program; if not, write to the Free Software
  30     Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  31
  32 */
  33
  34 #include <asm/errno.h>
  35 #include <linux/init.h>
  36 #include <linux/module.h>
  37 #include <linux/string.h>
  38 #include <linux/i2c.h>
  39 #include <linux/etherdevice.h>
  40
  41 #include "ttpci-eeprom.h"
  42
  43 #if 1
  44 #define dprintk(x...) do { printk(x); } while (0)
  45 #else
  46 #define dprintk(x...) do { } while (0)
  47 #endif
  48
  49
  50 static int check_mac_tt(u8 *buf)
  51 {
  52         int i;
  53         u16 tmp = 0xffff;
  54
  55         for (i = 0; i < 8; i++) {
  56                 tmp  = (tmp << 8) | ((tmp >> 8) ^ buf[i]);
  57                 tmp ^= (tmp >> 4) & 0x0f;
  58                 tmp ^= (tmp << 12) ^ ((tmp & 0xff) << 5);
  59         }
  60         tmp ^= 0xffff;
  61         return (((tmp >> 8) ^ buf[8]) | ((tmp & 0xff) ^ buf[9]));
  62 }
  63
  64 static int getmac_tt(u8 * decodedMAC, u8 * encodedMAC)
  65 {
  66         u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
  67                        0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
  68                        0x1d, 0x36, 0x64, 0x78};
  69         u8 data[20];
  70         int i;
  71
  72         /* In case there is a sig check failure have the orig contents available */
  73         memcpy(data, encodedMAC, 20);
  74
  75         for (i = 0; i < 20; i++)
  76                 data[i] ^= xor[i];
  77         for (i = 0; i < 10; i++)
  78                 data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
  79                         >> ((data[2 * i + 1] >> 6) & 3);
  80
  81         if (check_mac_tt(data))
  82                 return -ENODEV;
  83
  84         decodedMAC[0] = data[2]; decodedMAC[1] = data[1]; decodedMAC[2] = data[0];
  85         decodedMAC[3] = data[6]; decodedMAC[4] = data[5]; decodedMAC[5] = data[4];
  86         return 0;
  87 }
  88
  89 int ttpci_eeprom_decode_mac(u8 *decodedMAC, u8 *encodedMAC)
  90 {
  91         u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
  92                        0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
  93                        0x1d, 0x36, 0x64, 0x78};
  94         u8 data[20];
  95         int i;
  96
  97         memcpy(data, encodedMAC, 20);
  98
  99         for (i = 0; i < 20; i++)
 100                 data[i] ^= xor[i];
 101         for (i = 0; i < 10; i++)
 102                 data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
 103                         >> ((data[2 * i + 1] >> 6) & 3);
 104
 105         if (check_mac_tt(data))
 106                 return -ENODEV;
 107
 108         decodedMAC[0] = data[2];
 109         decodedMAC[1] = data[1];
 110         decodedMAC[2] = data[0];
 111         decodedMAC[3] = data[6];
 112         decodedMAC[4] = data[5];
 113         decodedMAC[5] = data[4];
 114         return 0;
 115 }
 116 EXPORT_SYMBOL(ttpci_eeprom_decode_mac);
 117
 118 static int ttpci_eeprom_read_encodedMAC(struct i2c_adapter *adapter, u8 * encodedMAC)
 119 {
 120         int ret;
 121         u8 b0[] = { 0xcc };
 122
 123         struct i2c_msg msg[] = {
 124                 { .addr = 0x50, .flags = 0, .buf = b0, .len = 1 },
 125                 { .addr = 0x50, .flags = I2C_M_RD, .buf = encodedMAC, .len = 20 }
 126         };
 127
 128         /* dprintk("%s\n", __func__); */
 129
 130         ret = i2c_transfer(adapter, msg, 2);
 131
 132         if (ret != 2)           /* Assume EEPROM isn't there */
 133                 return (-ENODEV);
 134
 135         return 0;
 136 }
 137
 138
 139 int ttpci_eeprom_parse_mac(struct i2c_adapter *adapter, u8 *proposed_mac)
 140 {
 141         int ret, i;
 142         u8 encodedMAC[20];
 143         u8 decodedMAC[6];
 144
 145         ret = ttpci_eeprom_read_encodedMAC(adapter, encodedMAC);
 146
 147         if (ret != 0) {         /* Will only be -ENODEV */
 148                 dprintk("Couldn't read from EEPROM: not there?\n");
 149                 eth_zero_addr(proposed_mac);
 150                 return ret;
 151         }
 152
 153         ret = getmac_tt(decodedMAC, encodedMAC);
 154         if( ret != 0 ) {
 155                 dprintk("adapter failed MAC signature check\n");
 156                 dprintk("encoded MAC from EEPROM was " );
 157                 for(i=0; i<19; i++) {
 158                         dprintk( "%.2x:", encodedMAC[i]);
 159                 }
 160                 dprintk("%.2x\n", encodedMAC[19]);
 161                 eth_zero_addr(proposed_mac);
 162                 return ret;
 163         }
 164
 165         memcpy(proposed_mac, decodedMAC, 6);
 166         dprintk("adapter has MAC addr = %pM\n", decodedMAC);
 167         return 0;
 168 }
 169
 170 EXPORT_SYMBOL(ttpci_eeprom_parse_mac);
 171
 172 MODULE_LICENSE("GPL");
 173 MODULE_AUTHOR("Ralph Metzler, Marcus Metzler, others");
 174 MODULE_DESCRIPTION("Decode dvb_net MAC address from EEPROM of PCI DVB cards "
 175                 "made by Siemens, Technotrend, Hauppauge");