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#include <linux/etherdevice.h>
40
41#include "ttpci-eeprom.h"
42
43#if 1
44#define dprintk(x...) do { printk(x); } while (0)
45#else
46#define dprintk(x...) do { } while (0)
47#endif
48
49
50static int check_mac_tt(u8 *buf)
51{
52	int i;
53	u16 tmp = 0xffff;
54
55	for (i = 0; i < 8; i++) {
56		tmp  = (tmp << 8) | ((tmp >> 8) ^ buf[i]);
57		tmp ^= (tmp >> 4) & 0x0f;
58		tmp ^= (tmp << 12) ^ ((tmp & 0xff) << 5);
59	}
60	tmp ^= 0xffff;
61	return (((tmp >> 8) ^ buf[8]) | ((tmp & 0xff) ^ buf[9]));
62}
63
64static int getmac_tt(u8 * decodedMAC, u8 * encodedMAC)
65{
66	u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
67		       0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
68		       0x1d, 0x36, 0x64, 0x78};
69	u8 data[20];
70	int i;
71
72	/* In case there is a sig check failure have the orig contents available */
73	memcpy(data, encodedMAC, 20);
74
75	for (i = 0; i < 20; i++)
76		data[i] ^= xor[i];
77	for (i = 0; i < 10; i++)
78		data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
79			>> ((data[2 * i + 1] >> 6) & 3);
80
81	if (check_mac_tt(data))
82		return -ENODEV;
83
84	decodedMAC[0] = data[2]; decodedMAC[1] = data[1]; decodedMAC[2] = data[0];
85	decodedMAC[3] = data[6]; decodedMAC[4] = data[5]; decodedMAC[5] = data[4];
86	return 0;
87}
88
89int ttpci_eeprom_decode_mac(u8 *decodedMAC, u8 *encodedMAC)
90{
91	u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
92		       0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
93		       0x1d, 0x36, 0x64, 0x78};
94	u8 data[20];
95	int i;
96
97	memcpy(data, encodedMAC, 20);
98
99	for (i = 0; i < 20; i++)
100		data[i] ^= xor[i];
101	for (i = 0; i < 10; i++)
102		data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
103			>> ((data[2 * i + 1] >> 6) & 3);
104
105	if (check_mac_tt(data))
106		return -ENODEV;
107
108	decodedMAC[0] = data[2];
109	decodedMAC[1] = data[1];
110	decodedMAC[2] = data[0];
111	decodedMAC[3] = data[6];
112	decodedMAC[4] = data[5];
113	decodedMAC[5] = data[4];
114	return 0;
115}
116EXPORT_SYMBOL(ttpci_eeprom_decode_mac);
117
118static int ttpci_eeprom_read_encodedMAC(struct i2c_adapter *adapter, u8 * encodedMAC)
119{
120	int ret;
121	u8 b0[] = { 0xcc };
122
123	struct i2c_msg msg[] = {
124		{ .addr = 0x50, .flags = 0, .buf = b0, .len = 1 },
125		{ .addr = 0x50, .flags = I2C_M_RD, .buf = encodedMAC, .len = 20 }
126	};
127
128	/* dprintk("%s\n", __func__); */
129
130	ret = i2c_transfer(adapter, msg, 2);
131
132	if (ret != 2)		/* Assume EEPROM isn't there */
133		return (-ENODEV);
134
135	return 0;
136}
137
138
139int ttpci_eeprom_parse_mac(struct i2c_adapter *adapter, u8 *proposed_mac)
140{
141	int ret, i;
142	u8 encodedMAC[20];
143	u8 decodedMAC[6];
144
145	ret = ttpci_eeprom_read_encodedMAC(adapter, encodedMAC);
146
147	if (ret != 0) {		/* Will only be -ENODEV */
148		dprintk("Couldn't read from EEPROM: not there?\n");
149		eth_zero_addr(proposed_mac);
150		return ret;
151	}
152
153	ret = getmac_tt(decodedMAC, encodedMAC);
154	if( ret != 0 ) {
155		dprintk("adapter failed MAC signature check\n");
156		dprintk("encoded MAC from EEPROM was " );
157		for(i=0; i<19; i++) {
158			dprintk( "%.2x:", encodedMAC[i]);
159		}
160		dprintk("%.2x\n", encodedMAC[19]);
161		eth_zero_addr(proposed_mac);
162		return ret;
163	}
164
165	memcpy(proposed_mac, decodedMAC, 6);
166	dprintk("adapter has MAC addr = %pM\n", decodedMAC);
167	return 0;
168}
169
170EXPORT_SYMBOL(ttpci_eeprom_parse_mac);
171
172MODULE_LICENSE("GPL");
173MODULE_AUTHOR("Ralph Metzler, Marcus Metzler, others");
174MODULE_DESCRIPTION("Decode dvb_net MAC address from EEPROM of PCI DVB cards "
175		"made by Siemens, Technotrend, Hauppauge");
176