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/* ------------------------------------------------------------------------- */
/* i2c-algo-bit.c i2c driver algorithms for bit-shift adapters */
/* ------------------------------------------------------------------------- */
/* Copyright (C) 1995-2000 Simon G. Vogl
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. */
/* ------------------------------------------------------------------------- */
/* With some changes from Kyösti Mälkki <kmalkki@cc.hut.fi> and even
Frodo Looijaard <frodol@dds.nl> */
/* $Id: i2c-algo-bit.c,v 1.30 2001/07/29 02:44:25 mds Exp $ */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/version.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <linux/ioport.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include <linux/i2c.h>
#include <linux/i2c-algo-bit.h>
/* ----- global defines ----------------------------------------------- */
#define DEB(x) if (i2c_debug>=1) x;
#define DEB2(x) if (i2c_debug>=2) x;
#define DEBSTAT(x) if (i2c_debug>=3) x; /* print several statistical values*/
#define DEBPROTO(x) if (i2c_debug>=9) { x; }
/* debug the protocol by showing transferred bits */
/* debugging - slow down transfer to have a look at the data .. */
/* I use this with two leds&resistors, each one connected to sda,scl */
/* respectively. This makes sure that the algorithm works. Some chips */
/* might not like this, as they have an internal timeout of some mils */
/*
#define SLO_IO jif=jiffies;while(jiffies<=jif+i2c_table[minor].veryslow)\
if (need_resched) schedule();
*/
/* ----- global variables --------------------------------------------- */
#ifdef SLO_IO
int jif;
#endif
/* module parameters:
*/
static int i2c_debug;
static int bit_test; /* see if the line-setting functions work */
static int bit_scan; /* have a look at what's hanging 'round */
/* --- setting states on the bus with the right timing: --------------- */
#define setsda(adap,val) adap->setsda(adap->data, val)
#define setscl(adap,val) adap->setscl(adap->data, val)
#define getsda(adap) adap->getsda(adap->data)
#define getscl(adap) adap->getscl(adap->data)
static inline void sdalo(struct i2c_algo_bit_data *adap)
{
setsda(adap,0);
udelay(adap->udelay);
}
static inline void sdahi(struct i2c_algo_bit_data *adap)
{
setsda(adap,1);
udelay(adap->udelay);
}
static inline void scllo(struct i2c_algo_bit_data *adap)
{
setscl(adap,0);
udelay(adap->udelay);
#ifdef SLO_IO
SLO_IO
#endif
}
/*
* Raise scl line, and do checking for delays. This is necessary for slower
* devices.
*/
static inline int sclhi(struct i2c_algo_bit_data *adap)
{
int start=jiffies;
setscl(adap,1);
udelay(adap->udelay);
/* Not all adapters have scl sense line... */
if (adap->getscl == NULL )
return 0;
while (! getscl(adap) ) {
/* the hw knows how to read the clock line,
* so we wait until it actually gets high.
* This is safer as some chips may hold it low
* while they are processing data internally.
*/
setscl(adap,1);
if (start+adap->timeout <= jiffies) {
return -ETIMEDOUT;
}
if (current->need_resched)
schedule();
}
DEBSTAT(printk("needed %ld jiffies\n", jiffies-start));
#ifdef SLO_IO
SLO_IO
#endif
return 0;
}
/* --- other auxiliary functions -------------------------------------- */
static void i2c_start(struct i2c_algo_bit_data *adap)
{
/* assert: scl, sda are high */
DEBPROTO(printk("S "));
sdalo(adap);
scllo(adap);
}
static void i2c_repstart(struct i2c_algo_bit_data *adap)
{
/* scl, sda may not be high */
DEBPROTO(printk(" Sr "));
setsda(adap,1);
setscl(adap,1);
udelay(adap->udelay);
sdalo(adap);
scllo(adap);
}
static void i2c_stop(struct i2c_algo_bit_data *adap)
{
DEBPROTO(printk("P\n"));
/* assert: scl is low */
sdalo(adap);
sclhi(adap);
sdahi(adap);
}
/* send a byte without start cond., look for arbitration,
check ackn. from slave */
/* returns:
* 1 if the device acknowledged
* 0 if the device did not ack
* -ETIMEDOUT if an error occurred (while raising the scl line)
*/
static int i2c_outb(struct i2c_adapter *i2c_adap, char c)
{
int i;
int sb;
int ack;
struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
/* assert: scl is low */
DEB2(printk(" i2c_outb:%2.2X\n",c&0xff));
for ( i=7 ; i>=0 ; i-- ) {
sb = c & ( 1 << i );
setsda(adap,sb);
udelay(adap->udelay);
DEBPROTO(printk("%d",sb!=0));
if (sclhi(adap)<0) { /* timed out */
sdahi(adap); /* we don't want to block the net */
return -ETIMEDOUT;
};
/* do arbitration here:
* if ( sb && ! getsda(adap) ) -> ouch! Get out of here.
*/
setscl(adap, 0 );
udelay(adap->udelay);
}
sdahi(adap);
if (sclhi(adap)<0){ /* timeout */
return -ETIMEDOUT;
};
/* read ack: SDA should be pulled down by slave */
ack=getsda(adap); /* ack: sda is pulled low ->success. */
DEB2(printk(" i2c_outb: getsda() = 0x%2.2x\n", ~ack ));
DEBPROTO( printk("[%2.2x]",c&0xff) );
DEBPROTO(if (0==ack){ printk(" A ");} else printk(" NA ") );
scllo(adap);
return 0==ack; /* return 1 if device acked */
/* assert: scl is low (sda undef) */
}
static int i2c_inb(struct i2c_adapter *i2c_adap)
{
/* read byte via i2c port, without start/stop sequence */
/* acknowledge is sent in i2c_read. */
int i;
unsigned char indata=0;
struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
/* assert: scl is low */
DEB2(printk("i2c_inb.\n"));
sdahi(adap);
for (i=0;i<8;i++) {
if (sclhi(adap)<0) { /* timeout */
return -ETIMEDOUT;
};
indata *= 2;
if ( getsda(adap) )
indata |= 0x01;
scllo(adap);
}
/* assert: scl is low */
DEBPROTO(printk(" %2.2x", indata & 0xff));
return (int) (indata & 0xff);
}
/*
* Sanity check for the adapter hardware - check the reaction of
* the bus lines only if it seems to be idle.
*/
static int test_bus(struct i2c_algo_bit_data *adap, char* name) {
int scl,sda;
sda=getsda(adap);
if (adap->getscl==NULL) {
printk("i2c-algo-bit.o: Warning: Adapter can't read from clock line - skipping test.\n");
return 0;
}
scl=getscl(adap);
printk("i2c-algo-bit.o: Adapter: %s scl: %d sda: %d -- testing...\n",
name,getscl(adap),getsda(adap));
if (!scl || !sda ) {
printk("i2c-algo-bit.o: %s seems to be busy.\n",name);
goto bailout;
}
sdalo(adap);
printk("i2c-algo-bit.o:1 scl: %d sda: %d \n",getscl(adap),
getsda(adap));
if ( 0 != getsda(adap) ) {
printk("i2c-algo-bit.o: %s SDA stuck high!\n",name);
sdahi(adap);
goto bailout;
}
if ( 0 == getscl(adap) ) {
printk("i2c-algo-bit.o: %s SCL unexpected low while pulling SDA low!\n",
name);
goto bailout;
}
sdahi(adap);
printk("i2c-algo-bit.o:2 scl: %d sda: %d \n",getscl(adap),
getsda(adap));
if ( 0 == getsda(adap) ) {
printk("i2c-algo-bit.o: %s SDA stuck low!\n",name);
sdahi(adap);
goto bailout;
}
if ( 0 == getscl(adap) ) {
printk("i2c-algo-bit.o: %s SCL unexpected low while SDA high!\n",
name);
goto bailout;
}
scllo(adap);
printk("i2c-algo-bit.o:3 scl: %d sda: %d \n",getscl(adap),
getsda(adap));
if ( 0 != getscl(adap) ) {
printk("i2c-algo-bit.o: %s SCL stuck high!\n",name);
sclhi(adap);
goto bailout;
}
if ( 0 == getsda(adap) ) {
printk("i2c-algo-bit.o: %s SDA unexpected low while pulling SCL low!\n",
name);
goto bailout;
}
sclhi(adap);
printk("i2c-algo-bit.o:4 scl: %d sda: %d \n",getscl(adap),
getsda(adap));
if ( 0 == getscl(adap) ) {
printk("i2c-algo-bit.o: %s SCL stuck low!\n",name);
sclhi(adap);
goto bailout;
}
if ( 0 == getsda(adap) ) {
printk("i2c-algo-bit.o: %s SDA unexpected low while SCL high!\n",
name);
goto bailout;
}
printk("i2c-algo-bit.o: %s passed test.\n",name);
return 0;
bailout:
sdahi(adap);
sclhi(adap);
return -ENODEV;
}
/* ----- Utility functions
*/
/* try_address tries to contact a chip for a number of
* times before it gives up.
* return values:
* 1 chip answered
* 0 chip did not answer
* -x transmission error
*/
static inline int try_address(struct i2c_adapter *i2c_adap,
unsigned char addr, int retries)
{
struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
int i,ret = -1;
for (i=0;i<=retries;i++) {
ret = i2c_outb(i2c_adap,addr);
if (ret==1)
break; /* success! */
i2c_stop(adap);
udelay(5/*adap->udelay*/);
if (i==retries) /* no success */
break;
i2c_start(adap);
udelay(adap->udelay);
}
DEB2(if (i) printk("i2c-algo-bit.o: needed %d retries for %d\n",
i,addr));
return ret;
}
static int sendbytes(struct i2c_adapter *i2c_adap,const char *buf, int count)
{
struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
char c;
const char *temp = buf;
int retval;
int wrcount=0;
while (count > 0) {
c = *temp;
DEB2(printk("i2c-algo-bit.o: %s i2c_write: writing %2.2X\n",
i2c_adap->name, c&0xff));
retval = i2c_outb(i2c_adap,c);
if (retval>0) {
count--;
temp++;
wrcount++;
} else { /* arbitration or no acknowledge */
printk("i2c-algo-bit.o: %s i2c_write: error - bailout.\n",
i2c_adap->name);
i2c_stop(adap);
return (retval<0)? retval : -EFAULT;
/* got a better one ?? */
}
#if 0
/* from asm/delay.h */
__delay(adap->mdelay * (loops_per_sec / 1000) );
#endif
}
return wrcount;
}
static inline int readbytes(struct i2c_adapter *i2c_adap,char *buf,int count)
{
char *temp = buf;
int inval;
int rdcount=0; /* counts bytes read */
struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
while (count > 0) {
inval = i2c_inb(i2c_adap);
/*printk("%#02x ",inval); if ( ! (count % 16) ) printk("\n"); */
if (inval>=0) {
*temp = inval;
rdcount++;
} else { /* read timed out */
printk("i2c-algo-bit.o: i2c_read: i2c_inb timed out.\n");
break;
}
if ( count > 1 ) { /* send ack */
sdalo(adap);
DEBPROTO(printk(" Am "));
} else {
sdahi(adap); /* neg. ack on last byte */
DEBPROTO(printk(" NAm "));
}
if (sclhi(adap)<0) { /* timeout */
sdahi(adap);
printk("i2c-algo-bit.o: i2c_read: Timeout at ack\n");
return -ETIMEDOUT;
};
scllo(adap);
sdahi(adap);
temp++;
count--;
}
return rdcount;
}
/* doAddress initiates the transfer by generating the start condition (in
* try_address) and transmits the address in the necessary format to handle
* reads, writes as well as 10bit-addresses.
* returns:
* 0 everything went okay, the chip ack'ed
* -x an error occurred (like: -EREMOTEIO if the device did not answer, or
* -ETIMEDOUT, for example if the lines are stuck...)
*/
static inline int bit_doAddress(struct i2c_adapter *i2c_adap,
struct i2c_msg *msg, int retries)
{
unsigned short flags = msg->flags;
struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
unsigned char addr;
int ret;
if ( (flags & I2C_M_TEN) ) {
/* a ten bit address */
addr = 0xf0 | (( msg->addr >> 7) & 0x03);
DEB2(printk("addr0: %d\n",addr));
/* try extended address code...*/
ret = try_address(i2c_adap, addr, retries);
if (ret!=1) {
printk("died at extended address code.\n");
return -EREMOTEIO;
}
/* the remaining 8 bit address */
ret = i2c_outb(i2c_adap,msg->addr & 0x7f);
if (ret != 1) {
/* the chip did not ack / xmission error occurred */
printk("died at 2nd address code.\n");
return -EREMOTEIO;
}
if ( flags & I2C_M_RD ) {
i2c_repstart(adap);
/* okay, now switch into reading mode */
addr |= 0x01;
ret = try_address(i2c_adap, addr, retries);
if (ret!=1) {
printk("died at extended address code.\n");
return -EREMOTEIO;
}
}
} else { /* normal 7bit address */
addr = ( msg->addr << 1 );
if (flags & I2C_M_RD )
addr |= 1;
if (flags & I2C_M_REV_DIR_ADDR )
addr ^= 1;
ret = try_address(i2c_adap, addr, retries);
if (ret!=1) {
return -EREMOTEIO;
}
}
return 0;
}
static int bit_xfer(struct i2c_adapter *i2c_adap,
struct i2c_msg msgs[], int num)
{
struct i2c_msg *pmsg;
struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
int i,ret;
i2c_start(adap);
for (i=0;i<num;i++) {
pmsg = &msgs[i];
if (!(pmsg->flags & I2C_M_NOSTART)) {
if (i) {
i2c_repstart(adap);
}
ret = bit_doAddress(i2c_adap,pmsg,i2c_adap->retries);
if (ret != 0) {
DEB2(printk("i2c-algo-bit.o: NAK from device adr %#2x msg #%d\n"
,msgs[i].addr,i));
return (ret<0) ? ret : -EREMOTEIO;
}
}
if (pmsg->flags & I2C_M_RD ) {
/* read bytes into buffer*/
ret = readbytes(i2c_adap,pmsg->buf,pmsg->len);
DEB2(printk("i2c-algo-bit.o: read %d bytes.\n",ret));
if (ret < pmsg->len ) {
return (ret<0)? ret : -EREMOTEIO;
}
} else {
/* write bytes from buffer */
ret = sendbytes(i2c_adap,pmsg->buf,pmsg->len);
DEB2(printk("i2c-algo-bit.o: wrote %d bytes.\n",ret));
if (ret < pmsg->len ) {
return (ret<0) ? ret : -EREMOTEIO;
}
}
}
i2c_stop(adap);
return num;
}
static int algo_control(struct i2c_adapter *adapter,
unsigned int cmd, unsigned long arg)
{
return 0;
}
static u32 bit_func(struct i2c_adapter *adap)
{
return I2C_FUNC_SMBUS_EMUL | I2C_FUNC_10BIT_ADDR |
I2C_FUNC_PROTOCOL_MANGLING;
}
/* -----exported algorithm data: ------------------------------------- */
static struct i2c_algorithm i2c_bit_algo = {
"Bit-shift algorithm",
I2C_ALGO_BIT,
bit_xfer,
NULL,
NULL, /* slave_xmit */
NULL, /* slave_recv */
algo_control, /* ioctl */
bit_func, /* functionality */
};
/*
* registering functions to load algorithms at runtime
*/
int i2c_bit_add_bus(struct i2c_adapter *adap)
{
int i;
struct i2c_algo_bit_data *bit_adap = adap->algo_data;
if (bit_test) {
int ret = test_bus(bit_adap, adap->name);
if (ret<0)
return -ENODEV;
}
DEB2(printk("i2c-algo-bit.o: hw routines for %s registered.\n",
adap->name));
/* register new adapter to i2c module... */
adap->id |= i2c_bit_algo.id;
adap->algo = &i2c_bit_algo;
adap->timeout = 100; /* default values, should */
adap->retries = 3; /* be replaced by defines */
/* scan bus */
if (bit_scan) {
int ack;
printk(KERN_INFO " i2c-algo-bit.o: scanning bus %s.\n",
adap->name);
for (i = 0x00; i < 0xff; i+=2) {
i2c_start(bit_adap);
ack = i2c_outb(adap,i);
i2c_stop(bit_adap);
if (ack>0) {
printk("(%02x)",i>>1);
} else
printk(".");
}
printk("\n");
}
#ifdef MODULE
MOD_INC_USE_COUNT;
#endif
i2c_add_adapter(adap);
return 0;
}
int i2c_bit_del_bus(struct i2c_adapter *adap)
{
int res;
if ((res = i2c_del_adapter(adap)) < 0)
return res;
DEB2(printk("i2c-algo-bit.o: adapter unregistered: %s\n",adap->name));
#ifdef MODULE
MOD_DEC_USE_COUNT;
#endif
return 0;
}
int __init i2c_algo_bit_init (void)
{
printk("i2c-algo-bit.o: i2c bit algorithm module\n");
return 0;
}
EXPORT_SYMBOL(i2c_bit_add_bus);
EXPORT_SYMBOL(i2c_bit_del_bus);
#ifdef MODULE
MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
MODULE_LICENSE("GPL");
MODULE_PARM(bit_test, "i");
MODULE_PARM(bit_scan, "i");
MODULE_PARM(i2c_debug,"i");
MODULE_PARM_DESC(bit_test, "Test the lines of the bus to see if it is stuck");
MODULE_PARM_DESC(bit_scan, "Scan for active chips on the bus");
MODULE_PARM_DESC(i2c_debug,
"debug level - 0 off; 1 normal; 2,3 more verbose; 9 bit-protocol");
int init_module(void)
{
return i2c_algo_bit_init();
}
void cleanup_module(void)
{
}
#endif
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