media/common/ttpci-eeprom.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003     Retrieve encoded MAC address from 24C16 serial 2-wire EEPROM,
0004     decode it and store it in the associated adapter struct for
0005     use by dvb_net.c
0006
0007     This card appear to have the 24C16 write protect held to ground,
0008     thus permitting normal read/write operation. Theoretically it
0009     would be possible to write routines to burn a different (encoded)
0010     MAC address into the EEPROM.
0011
0012     Robert Schlabbach   GMX
0013     Michael Glaum   KVH Industries
0014     Holger Waechtler    Convergence
0015
0016     Copyright (C) 2002-2003 Ralph Metzler <rjkm@metzlerbros.de>
0017                 Metzler Brothers Systementwicklung GbR
0018
0019
0020 */
0021
0022 #include <asm/errno.h>
0023 #include <linux/init.h>
0024 #include <linux/module.h>
0025 #include <linux/string.h>
0026 #include <linux/i2c.h>
0027 #include <linux/etherdevice.h>
0028
0029 #include "ttpci-eeprom.h"
0030
0031 #if 1
0032 #define dprintk(x...) do { printk(x); } while (0)
0033 #else
0034 #define dprintk(x...) do { } while (0)
0035 #endif
0036
0037
0038 static int check_mac_tt(u8 *buf)
0039 {
0040     int i;
0041     u16 tmp = 0xffff;
0042
0043     for (i = 0; i < 8; i++) {
0044         tmp  = (tmp << 8) | ((tmp >> 8) ^ buf[i]);
0045         tmp ^= (tmp >> 4) & 0x0f;
0046         tmp ^= (tmp << 12) ^ ((tmp & 0xff) << 5);
0047     }
0048     tmp ^= 0xffff;
0049     return (((tmp >> 8) ^ buf[8]) | ((tmp & 0xff) ^ buf[9]));
0050 }
0051
0052 static int getmac_tt(u8 * decodedMAC, u8 * encodedMAC)
0053 {
0054     u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
0055                0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
0056                0x1d, 0x36, 0x64, 0x78};
0057     u8 data[20];
0058     int i;
0059
0060     /* In case there is a sig check failure have the orig contents available */
0061     memcpy(data, encodedMAC, 20);
0062
0063     for (i = 0; i < 20; i++)
0064         data[i] ^= xor[i];
0065     for (i = 0; i < 10; i++)
0066         data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
0067             >> ((data[2 * i + 1] >> 6) & 3);
0068
0069     if (check_mac_tt(data))
0070         return -ENODEV;
0071
0072     decodedMAC[0] = data[2]; decodedMAC[1] = data[1]; decodedMAC[2] = data[0];
0073     decodedMAC[3] = data[6]; decodedMAC[4] = data[5]; decodedMAC[5] = data[4];
0074     return 0;
0075 }
0076
0077 int ttpci_eeprom_decode_mac(u8 *decodedMAC, u8 *encodedMAC)
0078 {
0079     u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
0080                0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
0081                0x1d, 0x36, 0x64, 0x78};
0082     u8 data[20];
0083     int i;
0084
0085     memcpy(data, encodedMAC, 20);
0086
0087     for (i = 0; i < 20; i++)
0088         data[i] ^= xor[i];
0089     for (i = 0; i < 10; i++)
0090         data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
0091             >> ((data[2 * i + 1] >> 6) & 3);
0092
0093     if (check_mac_tt(data))
0094         return -ENODEV;
0095
0096     decodedMAC[0] = data[2];
0097     decodedMAC[1] = data[1];
0098     decodedMAC[2] = data[0];
0099     decodedMAC[3] = data[6];
0100     decodedMAC[4] = data[5];
0101     decodedMAC[5] = data[4];
0102     return 0;
0103 }
0104 EXPORT_SYMBOL(ttpci_eeprom_decode_mac);
0105
0106 static int ttpci_eeprom_read_encodedMAC(struct i2c_adapter *adapter, u8 * encodedMAC)
0107 {
0108     int ret;
0109     u8 b0[] = { 0xcc };
0110
0111     struct i2c_msg msg[] = {
0112         { .addr = 0x50, .flags = 0, .buf = b0, .len = 1 },
0113         { .addr = 0x50, .flags = I2C_M_RD, .buf = encodedMAC, .len = 20 }
0114     };
0115
0116     /* dprintk("%s\n", __func__); */
0117
0118     ret = i2c_transfer(adapter, msg, 2);
0119
0120     if (ret != 2)       /* Assume EEPROM isn't there */
0121         return (-ENODEV);
0122
0123     return 0;
0124 }
0125
0126
0127 int ttpci_eeprom_parse_mac(struct i2c_adapter *adapter, u8 *proposed_mac)
0128 {
0129     int ret;
0130     u8 encodedMAC[20];
0131     u8 decodedMAC[6];
0132
0133     ret = ttpci_eeprom_read_encodedMAC(adapter, encodedMAC);
0134
0135     if (ret != 0) {     /* Will only be -ENODEV */
0136         dprintk("Couldn't read from EEPROM: not there?\n");
0137         eth_zero_addr(proposed_mac);
0138         return ret;
0139     }
0140
0141     ret = getmac_tt(decodedMAC, encodedMAC);
0142     if( ret != 0 ) {
0143         dprintk("adapter failed MAC signature check\n");
0144         dprintk("encoded MAC from EEPROM was %*phC",
0145             (int)sizeof(encodedMAC), &encodedMAC);
0146         eth_zero_addr(proposed_mac);
0147         return ret;
0148     }
0149
0150     memcpy(proposed_mac, decodedMAC, 6);
0151     dprintk("adapter has MAC addr = %pM\n", decodedMAC);
0152     return 0;
0153 }
0154
0155 EXPORT_SYMBOL(ttpci_eeprom_parse_mac);
0156
0157 MODULE_LICENSE("GPL");
0158 MODULE_AUTHOR("Ralph Metzler, Marcus Metzler, others");
0159 MODULE_DESCRIPTION("Decode dvb_net MAC address from EEPROM of PCI DVB cards made by Siemens, Technotrend, Hauppauge");