ttpci_eeprom.c

linux TV 源码

/*
    Retrieve encoded MAC address from 24C16 serial 2-wire EEPROM,
    decode it and store it in the associated adapter struct for
    use by dvb_net.c

    This card appear to have the 24C16 write protect held to ground,
    thus permitting normal read/write operation. Theoretically it
    would be possible to write routines to burn a different (encoded)
    MAC address into the EEPROM.

    Robert Schlabbach	GMX
    Michael Glaum	KVH Industries
    Holger Waechtler	Convergence

    Copyright (C) 2002-2003 Ralph Metzler <[e-mail]>
                            Metzler Brothers Systementwicklung GbR

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

*/

#include <asm/errno.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>

#include "dvb_i2c.h"
#include "compat.h"

#if 1
#define dprintk(x...) printk(x)
#else
#define dprintk(x...)
#endif

static
int check_mac_tt(u8 *buf)
{
        int i;
        u16 tmp=0xffff;

        for (i=0; i<8; i++) {
                tmp =(tmp<<8)|((tmp>>8)^buf[i]);
                tmp^=(tmp>>4)&0x0f;
                tmp^=(tmp<<12)^((tmp&0xff)<<5);
        }
        tmp^=0xffff;
        return (((tmp>>8)^buf[8])|((tmp&0xff)^buf[9]));
}

static
int getmac_tt(u8 * decodedMAC, u8 * encodedMAC)
{
        u8 xor[20]={0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
                    0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
                    0x1d, 0x36, 0x64, 0x78};
        u8 data[20];
        int i;

	// In case there is a sig check failure have the orig contents available
	memcpy( data, encodedMAC, 20 );

	for (i=0; i<20; i++)
                data[i]^=xor[i];
        for(i=0; i<10; i++)
                data[i]=((data[2*i+1]<<8)|data[2*i]) >>
                        ((data[2*i+1]>> 6)&3);

        if (check_mac_tt(data)) {
                return -ENODEV;
        }

	decodedMAC[0]=data[2]; decodedMAC[1]=data[1]; decodedMAC[2]=data[0];
	decodedMAC[3]=data[6]; decodedMAC[4]=data[5]; decodedMAC[5]=data[4];
        return 0;
}


static
int ttpci_eeprom_read_encodedMAC (struct dvb_i2c_bus *i2c, u8 * encodedMAC )
{
	int ret;
	u8 b0 [] = { 0xcc };
	struct i2c_msg msg [] = { { addr: 0x50, flags: 0, buf: b0, len: 1 },
		   { addr: 0x50, flags: I2C_M_RD, buf: encodedMAC, len: 20 } };

	//dprintk ("%s\n", __FUNCTION__);

	ret = i2c->xfer (i2c, msg, 2);

	if (ret != 2) // Assume EEPROM isn't there
		return( -ENODEV );

	return 0;
}


int ttpci_eeprom_parse_mac(struct dvb_i2c_bus *i2c)
{
	int ret, i;
	u8 encodedMAC[20];
	u8 decodedMAC[6];

	ret = ttpci_eeprom_read_encodedMAC(i2c, encodedMAC);

	if (ret != 0) { // Will only be -ENODEV
		dprintk("Couldn't read from EEPROM: not there?\n");
		memset(i2c->adapter->proposed_mac, 0, 6);
		return ret;
	}

	ret = getmac_tt(decodedMAC, encodedMAC);
	if( ret != 0 ) {
		dprintk("%s adapter %i failed MAC signature check\n",
			i2c->adapter->name, i2c->adapter->num);
		dprintk("encoded MAC from EEPROM was " );
		for(i=0; i<19; i++) {
			dprintk( "%.2x:", encodedMAC[i]);
		}
		dprintk("%.2x\n", encodedMAC[19]);
		memset(i2c->adapter->proposed_mac, 0, 6);
		return ret;
	}

	memcpy(i2c->adapter->proposed_mac, decodedMAC, 6);
        dprintk("%s adapter %i has MAC addr = %.2x:%.2x:%.2x:%.2x:%.2x:%.2x\n",
		i2c->adapter->name, i2c->adapter->num,
		decodedMAC[0],decodedMAC[1],decodedMAC[2],
		decodedMAC[3],decodedMAC[4],decodedMAC[5]);
	return 0;
}