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
  39 #include "dvb_i2c.h"
  40 #include "dvb_functions.h"
  41
  42 #if 1
  43 #define dprintk(x...) do { printk(x); } while (0)
  44 #else
  45 #define dprintk(x...) do { } while (0)
  46 #endif
  47
  48
  49 static int check_mac_tt(u8 *buf)
  50 {
  51         int i;
  52         u16 tmp = 0xffff;
  53
  54         for (i = 0; i < 8; i++) {
  55                 tmp  = (tmp << 8) | ((tmp >> 8) ^ buf[i]);
  56                 tmp ^= (tmp >> 4) & 0x0f;
  57                 tmp ^= (tmp << 12) ^ ((tmp & 0xff) << 5);
  58         }
  59         tmp ^= 0xffff;
  60         return (((tmp >> 8) ^ buf[8]) | ((tmp & 0xff) ^ buf[9]));
  61 }
  62
  63 static int getmac_tt(u8 * decodedMAC, u8 * encodedMAC)
  64 {
  65         u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
  66                        0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
  67                        0x1d, 0x36, 0x64, 0x78};
  68         u8 data[20];
  69         int i;
  70
  71         /* In case there is a sig check failure have the orig contents available */
  72         memcpy(data, encodedMAC, 20);
  73
  74         for (i = 0; i < 20; i++)
  75                 data[i] ^= xor[i];
  76         for (i = 0; i < 10; i++)
  77                 data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
  78                         >> ((data[2 * i + 1] >> 6) & 3);
  79
  80         if (check_mac_tt(data))
  81                 return -ENODEV;
  82
  83         decodedMAC[0] = data[2]; decodedMAC[1] = data[1]; decodedMAC[2] = data[0];
  84         decodedMAC[3] = data[6]; decodedMAC[4] = data[5]; decodedMAC[5] = data[4];
  85         return 0;
  86 }
  87
  88 static int ttpci_eeprom_read_encodedMAC(struct dvb_i2c_bus *i2c, u8 * encodedMAC)
  89 {
  90         int ret;
  91         u8 b0[] = { 0xcc };
  92
  93         struct i2c_msg msg[] = {
  94                 {.addr = 0x50,.flags = 0,.buf = b0,.len = 1},
  95                 { .addr = 0x50, .flags = I2C_M_RD, .buf = encodedMAC, .len = 20 }
  96         };
  97
  98         /* dprintk("%s\n", __FUNCTION__); */
  99
 100         ret = i2c->xfer(i2c, msg, 2);
 101
 102         if (ret != 2)           /* Assume EEPROM isn't there */
 103                 return (-ENODEV);
 104
 105         return 0;
 106 }
 107
 108
 109 int ttpci_eeprom_parse_mac(struct dvb_i2c_bus *i2c)
 110 {
 111         int ret, i;
 112         u8 encodedMAC[20];
 113         u8 decodedMAC[6];
 114
 115         ret = ttpci_eeprom_read_encodedMAC(i2c, encodedMAC);
 116
 117         if (ret != 0) {         /* Will only be -ENODEV */
 118                 dprintk("Couldn't read from EEPROM: not there?\n");
 119                 memset(i2c->adapter->proposed_mac, 0, 6);
 120                 return ret;
 121         }
 122
 123         ret = getmac_tt(decodedMAC, encodedMAC);
 124         if( ret != 0 ) {
 125                 dprintk("%s adapter %i failed MAC signature check\n",
 126                         i2c->adapter->name, i2c->adapter->num);
 127                 dprintk("encoded MAC from EEPROM was " );
 128                 for(i=0; i<19; i++) {
 129                         dprintk( "%.2x:", encodedMAC[i]);
 130                 }
 131                 dprintk("%.2x\n", encodedMAC[19]);
 132                 memset(i2c->adapter->proposed_mac, 0, 6);
 133                 return ret;
 134         }
 135
 136         memcpy(i2c->adapter->proposed_mac, decodedMAC, 6);
 137         dprintk("%s adapter %i has MAC addr = %.2x:%.2x:%.2x:%.2x:%.2x:%.2x\n",
 138                 i2c->adapter->name, i2c->adapter->num,
 139                 decodedMAC[0], decodedMAC[1], decodedMAC[2],
 140                 decodedMAC[3], decodedMAC[4], decodedMAC[5]);
 141         return 0;
 142 }
 143
 144 EXPORT_SYMBOL(ttpci_eeprom_parse_mac);