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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 Retrieve encoded MAC address from 24C16 serial 2-wire EEPROM,4 decode it and store it in the associated adapter struct for5 use by dvb_net.c6 7 This card appear to have the 24C16 write protect held to ground,8 thus permitting normal read/write operation. Theoretically it9 would be possible to write routines to burn a different (encoded)10 MAC address into the EEPROM.11 12 Robert Schlabbach GMX13 Michael Glaum KVH Industries14 Holger Waechtler Convergence15 16 Copyright (C) 2002-2003 Ralph Metzler <rjkm@metzlerbros.de>17 Metzler Brothers Systementwicklung GbR18 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 132#define dprintk(x...) do { printk(x); } while (0)33#else34#define dprintk(x...) do { } while (0)35#endif36 37 38static 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 52static 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 77int 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}104EXPORT_SYMBOL(ttpci_eeprom_decode_mac);105 106static 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 127int 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 155EXPORT_SYMBOL(ttpci_eeprom_parse_mac);156 157MODULE_LICENSE("GPL");158MODULE_AUTHOR("Ralph Metzler, Marcus Metzler, others");159MODULE_DESCRIPTION("Decode dvb_net MAC address from EEPROM of PCI DVB cards made by Siemens, Technotrend, Hauppauge");160