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

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3     Retrieve encoded MAC address from 24C16 serial 2-wire EEPROM,
   4     decode it and store it in the associated adapter struct for
   5     use by dvb_net.c
   6
   7     This card appear to have the 24C16 write protect held to ground,
   8     thus permitting normal read/write operation. Theoretically it
   9     would be possible to write routines to burn a different (encoded)
  10     MAC address into the EEPROM.
  11
  12     Robert Schlabbach   GMX
  13     Michael Glaum       KVH Industries
  14     Holger Waechtler    Convergence
  15
  16     Copyright (C) 2002-2003 Ralph Metzler <rjkm@metzlerbros.de>
  17                             Metzler Brothers Systementwicklung GbR
  18
  19
  20 */
  21
  22 #include <asm/errno.h>
  23 #include <linux/init.h>
  24 #include <linux/module.h>
  25 #include <linux/string.h>
  26 #include <linux/i2c.h>
  27 #include <linux/etherdevice.h>
  28
  29 #include "ttpci-eeprom.h"
  30
  31 #if 1
  32 #define dprintk(x...) do { printk(x); } while (0)
  33 #else
  34 #define dprintk(x...) do { } while (0)
  35 #endif
  36
  37
  38 static int check_mac_tt(u8 *buf)
  39 {
  40         int i;
  41         u16 tmp = 0xffff;
  42
  43         for (i = 0; i < 8; i++) {
  44                 tmp  = (tmp << 8) | ((tmp >> 8) ^ buf[i]);
  45                 tmp ^= (tmp >> 4) & 0x0f;
  46                 tmp ^= (tmp << 12) ^ ((tmp & 0xff) << 5);
  47         }
  48         tmp ^= 0xffff;
  49         return (((tmp >> 8) ^ buf[8]) | ((tmp & 0xff) ^ buf[9]));
  50 }
  51
  52 static int getmac_tt(u8 * decodedMAC, u8 * encodedMAC)
  53 {
  54         u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
  55                        0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
  56                        0x1d, 0x36, 0x64, 0x78};
  57         u8 data[20];
  58         int i;
  59
  60         /* In case there is a sig check failure have the orig contents available */
  61         memcpy(data, encodedMAC, 20);
  62
  63         for (i = 0; i < 20; i++)
  64                 data[i] ^= xor[i];
  65         for (i = 0; i < 10; i++)
  66                 data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
  67                         >> ((data[2 * i + 1] >> 6) & 3);
  68
  69         if (check_mac_tt(data))
  70                 return -ENODEV;
  71
  72         decodedMAC[0] = data[2]; decodedMAC[1] = data[1]; decodedMAC[2] = data[0];
  73         decodedMAC[3] = data[6]; decodedMAC[4] = data[5]; decodedMAC[5] = data[4];
  74         return 0;
  75 }
  76
  77 int ttpci_eeprom_decode_mac(u8 *decodedMAC, u8 *encodedMAC)
  78 {
  79         u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
  80                        0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
  81                        0x1d, 0x36, 0x64, 0x78};
  82         u8 data[20];
  83         int i;
  84
  85         memcpy(data, encodedMAC, 20);
  86
  87         for (i = 0; i < 20; i++)
  88                 data[i] ^= xor[i];
  89         for (i = 0; i < 10; i++)
  90                 data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
  91                         >> ((data[2 * i + 1] >> 6) & 3);
  92
  93         if (check_mac_tt(data))
  94                 return -ENODEV;
  95
  96         decodedMAC[0] = data[2];
  97         decodedMAC[1] = data[1];
  98         decodedMAC[2] = data[0];
  99         decodedMAC[3] = data[6];
 100         decodedMAC[4] = data[5];
 101         decodedMAC[5] = data[4];
 102         return 0;
 103 }
 104 EXPORT_SYMBOL(ttpci_eeprom_decode_mac);
 105
 106 static int ttpci_eeprom_read_encodedMAC(struct i2c_adapter *adapter, u8 * encodedMAC)
 107 {
 108         int ret;
 109         u8 b0[] = { 0xcc };
 110
 111         struct i2c_msg msg[] = {
 112                 { .addr = 0x50, .flags = 0, .buf = b0, .len = 1 },
 113                 { .addr = 0x50, .flags = I2C_M_RD, .buf = encodedMAC, .len = 20 }
 114         };
 115
 116         /* dprintk("%s\n", __func__); */
 117
 118         ret = i2c_transfer(adapter, msg, 2);
 119
 120         if (ret != 2)           /* Assume EEPROM isn't there */
 121                 return (-ENODEV);
 122
 123         return 0;
 124 }
 125
 126
 127 int ttpci_eeprom_parse_mac(struct i2c_adapter *adapter, u8 *proposed_mac)
 128 {
 129         int ret;
 130         u8 encodedMAC[20];
 131         u8 decodedMAC[6];
 132
 133         ret = ttpci_eeprom_read_encodedMAC(adapter, encodedMAC);
 134
 135         if (ret != 0) {         /* Will only be -ENODEV */
 136                 dprintk("Couldn't read from EEPROM: not there?\n");
 137                 eth_zero_addr(proposed_mac);
 138                 return ret;
 139         }
 140
 141         ret = getmac_tt(decodedMAC, encodedMAC);
 142         if( ret != 0 ) {
 143                 dprintk("adapter failed MAC signature check\n");
 144                 dprintk("encoded MAC from EEPROM was %*phC",
 145                         (int)sizeof(encodedMAC), &encodedMAC);
 146                 eth_zero_addr(proposed_mac);
 147                 return ret;
 148         }
 149
 150         memcpy(proposed_mac, decodedMAC, 6);
 151         dprintk("adapter has MAC addr = %pM\n", decodedMAC);
 152         return 0;
 153 }
 154
 155 EXPORT_SYMBOL(ttpci_eeprom_parse_mac);
 156
 157 MODULE_LICENSE("GPL");
 158 MODULE_AUTHOR("Ralph Metzler, Marcus Metzler, others");
 159 MODULE_DESCRIPTION("Decode dvb_net MAC address from EEPROM of PCI DVB cards made by Siemens, Technotrend, Hauppauge");