drivers/media/dvb/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
  40
  41 #if 1
  42 #define dprintk(x...) do { printk(x); } while (0)
  43 #else
  44 #define dprintk(x...) do { } while (0)
  45 #endif
  46
  47
  48 static int check_mac_tt(u8 *buf)
  49 {
  50         int i;
  51         u16 tmp = 0xffff;
  52
  53         for (i = 0; i < 8; i++) {
  54                 tmp  = (tmp << 8) | ((tmp >> 8) ^ buf[i]);
  55                 tmp ^= (tmp >> 4) & 0x0f;
  56                 tmp ^= (tmp << 12) ^ ((tmp & 0xff) << 5);
  57         }
  58         tmp ^= 0xffff;
  59         return (((tmp >> 8) ^ buf[8]) | ((tmp & 0xff) ^ buf[9]));
  60 }
  61
  62 static int getmac_tt(u8 * decodedMAC, u8 * encodedMAC)
  63 {
  64         u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
  65                        0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
  66                        0x1d, 0x36, 0x64, 0x78};
  67         u8 data[20];
  68         int i;
  69
  70         /* In case there is a sig check failure have the orig contents available */
  71         memcpy(data, encodedMAC, 20);
  72
  73         for (i = 0; i < 20; i++)
  74                 data[i] ^= xor[i];
  75         for (i = 0; i < 10; i++)
  76                 data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
  77                         >> ((data[2 * i + 1] >> 6) & 3);
  78
  79         if (check_mac_tt(data))
  80                 return -ENODEV;
  81
  82         decodedMAC[0] = data[2]; decodedMAC[1] = data[1]; decodedMAC[2] = data[0];
  83         decodedMAC[3] = data[6]; decodedMAC[4] = data[5]; decodedMAC[5] = data[4];
  84         return 0;
  85 }
  86
  87 static int ttpci_eeprom_read_encodedMAC(struct i2c_adapter *adapter, u8 * encodedMAC)
  88 {
  89         int ret;
  90         u8 b0[] = { 0xcc };
  91
  92         struct i2c_msg msg[] = {
  93                 { .addr = 0x50, .flags = 0, .buf = b0, .len = 1 },
  94                 { .addr = 0x50, .flags = I2C_M_RD, .buf = encodedMAC, .len = 20 }
  95         };
  96
  97         /* dprintk("%s\n", __FUNCTION__); */
  98
  99         ret = i2c_transfer(adapter, msg, 2);
 100
 101         if (ret != 2)           /* Assume EEPROM isn't there */
 102                 return (-ENODEV);
 103
 104         return 0;
 105 }
 106
 107
 108 int ttpci_eeprom_parse_mac(struct i2c_adapter *adapter, u8 *proposed_mac)
 109 {
 110         int ret, i;
 111         u8 encodedMAC[20];
 112         u8 decodedMAC[6];
 113
 114         ret = ttpci_eeprom_read_encodedMAC(adapter, encodedMAC);
 115
 116         if (ret != 0) {         /* Will only be -ENODEV */
 117                 dprintk("Couldn't read from EEPROM: not there?\n");
 118                 memset(proposed_mac, 0, 6);
 119                 return ret;
 120         }
 121
 122         ret = getmac_tt(decodedMAC, encodedMAC);
 123         if( ret != 0 ) {
 124                 dprintk("adapter failed MAC signature check\n");
 125                 dprintk("encoded MAC from EEPROM was " );
 126                 for(i=0; i<19; i++) {
 127                         dprintk( "%.2x:", encodedMAC[i]);
 128                 }
 129                 dprintk("%.2x\n", encodedMAC[19]);
 130                 memset(proposed_mac, 0, 6);
 131                 return ret;
 132         }
 133
 134         memcpy(proposed_mac, decodedMAC, 6);
 135         dprintk("adapter has MAC addr = %.2x:%.2x:%.2x:%.2x:%.2x:%.2x\n",
 136                 decodedMAC[0], decodedMAC[1], decodedMAC[2],
 137                 decodedMAC[3], decodedMAC[4], decodedMAC[5]);
 138         return 0;
 139 }
 140
 141 EXPORT_SYMBOL(ttpci_eeprom_parse_mac);
 142
 143 MODULE_LICENSE("GPL");
 144 MODULE_AUTHOR("Ralph Metzler, Marcus Metzler, others");
 145 MODULE_DESCRIPTION("Decode dvb_net MAC address from EEPROM of PCI DVB cards "
 146                 "made by Siemens, Technotrend, Hauppauge");