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
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(buf: 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(buf: 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(adap: adapter, msgs: msg, num: 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(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(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

source code of linux/drivers/media/common/ttpci-eeprom.c