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
40#include "ttpci-eeprom.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
49static 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
63static 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
88int ttpci_eeprom_decode_mac(u8 *decodedMAC, u8 *encodedMAC)
89{
90	u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
91		       0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
92		       0x1d, 0x36, 0x64, 0x78};
93	u8 data[20];
94	int i;
95
96	memcpy(data, encodedMAC, 20);
97
98	for (i = 0; i < 20; i++)
99		data[i] ^= xor[i];
100	for (i = 0; i < 10; i++)
101		data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
102			>> ((data[2 * i + 1] >> 6) & 3);
103
104	if (check_mac_tt(data))
105		return -ENODEV;
106
107	decodedMAC[0] = data[2];
108	decodedMAC[1] = data[1];
109	decodedMAC[2] = data[0];
110	decodedMAC[3] = data[6];
111	decodedMAC[4] = data[5];
112	decodedMAC[5] = data[4];
113	return 0;
114}
115EXPORT_SYMBOL(ttpci_eeprom_decode_mac);
116
117static int ttpci_eeprom_read_encodedMAC(struct i2c_adapter *adapter, u8 * encodedMAC)
118{
119	int ret;
120	u8 b0[] = { 0xcc };
121
122	struct i2c_msg msg[] = {
123		{ .addr = 0x50, .flags = 0, .buf = b0, .len = 1 },
124		{ .addr = 0x50, .flags = I2C_M_RD, .buf = encodedMAC, .len = 20 }
125	};
126
127	/* dprintk("%s\n", __func__); */
128
129	ret = i2c_transfer(adapter, msg, 2);
130
131	if (ret != 2)		/* Assume EEPROM isn't there */
132		return (-ENODEV);
133
134	return 0;
135}
136
137
138int ttpci_eeprom_parse_mac(struct i2c_adapter *adapter, u8 *proposed_mac)
139{
140	int ret, i;
141	u8 encodedMAC[20];
142	u8 decodedMAC[6];
143
144	ret = ttpci_eeprom_read_encodedMAC(adapter, encodedMAC);
145
146	if (ret != 0) {		/* Will only be -ENODEV */
147		dprintk("Couldn't read from EEPROM: not there?\n");
148		memset(proposed_mac, 0, 6);
149		return ret;
150	}
151
152	ret = getmac_tt(decodedMAC, encodedMAC);
153	if( ret != 0 ) {
154		dprintk("adapter failed MAC signature check\n");
155		dprintk("encoded MAC from EEPROM was " );
156		for(i=0; i<19; i++) {
157			dprintk( "%.2x:", encodedMAC[i]);
158		}
159		dprintk("%.2x\n", encodedMAC[19]);
160		memset(proposed_mac, 0, 6);
161		return ret;
162	}
163
164	memcpy(proposed_mac, decodedMAC, 6);
165	dprintk("adapter has MAC addr = %.2x:%.2x:%.2x:%.2x:%.2x:%.2x\n",
166		decodedMAC[0], decodedMAC[1], decodedMAC[2],
167		decodedMAC[3], decodedMAC[4], decodedMAC[5]);
168	return 0;
169}
170
171EXPORT_SYMBOL(ttpci_eeprom_parse_mac);
172
173MODULE_LICENSE("GPL");
174MODULE_AUTHOR("Ralph Metzler, Marcus Metzler, others");
175MODULE_DESCRIPTION("Decode dvb_net MAC address from EEPROM of PCI DVB cards "
176		"made by Siemens, Technotrend, Hauppauge");
177