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573 lines
15 KiB
573 lines
15 KiB
/* ------------------------------------------------------------------------- */
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/* i2c-algo-bit.c i2c driver algorithms for bit-shift adapters */
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/* ------------------------------------------------------------------------- */
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/* Copyright (C) 1995-2000 Simon G. Vogl
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */
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/* ------------------------------------------------------------------------- */
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/* With some changes from Frodo Looijaard <frodol@dds.nl>, Kyösti Mälkki
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<kmalkki@cc.hut.fi> and Jean Delvare <khali@linux-fr.org> */
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/delay.h>
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#include <linux/slab.h>
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#include <linux/init.h>
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#include <linux/errno.h>
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#include <linux/sched.h>
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#include <linux/i2c.h>
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#include <linux/i2c-algo-bit.h>
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/* ----- global defines ----------------------------------------------- */
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#define DEB(x) if (i2c_debug>=1) x;
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#define DEB2(x) if (i2c_debug>=2) x;
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#define DEBSTAT(x) if (i2c_debug>=3) x; /* print several statistical values*/
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#define DEBPROTO(x) if (i2c_debug>=9) { x; }
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/* debug the protocol by showing transferred bits */
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/* ----- global variables --------------------------------------------- */
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/* module parameters:
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*/
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static int i2c_debug;
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static int bit_test; /* see if the line-setting functions work */
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/* --- setting states on the bus with the right timing: --------------- */
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#define setsda(adap,val) adap->setsda(adap->data, val)
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#define setscl(adap,val) adap->setscl(adap->data, val)
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#define getsda(adap) adap->getsda(adap->data)
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#define getscl(adap) adap->getscl(adap->data)
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static inline void sdalo(struct i2c_algo_bit_data *adap)
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{
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setsda(adap,0);
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udelay(adap->udelay);
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}
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static inline void sdahi(struct i2c_algo_bit_data *adap)
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{
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setsda(adap,1);
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udelay(adap->udelay);
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}
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static inline void scllo(struct i2c_algo_bit_data *adap)
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{
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setscl(adap,0);
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udelay(adap->udelay);
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}
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/*
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* Raise scl line, and do checking for delays. This is necessary for slower
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* devices.
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*/
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static inline int sclhi(struct i2c_algo_bit_data *adap)
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{
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unsigned long start;
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setscl(adap,1);
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/* Not all adapters have scl sense line... */
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if (adap->getscl == NULL ) {
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udelay(adap->udelay);
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return 0;
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}
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start=jiffies;
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while (! getscl(adap) ) {
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/* the hw knows how to read the clock line,
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* so we wait until it actually gets high.
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* This is safer as some chips may hold it low
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* while they are processing data internally.
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*/
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if (time_after_eq(jiffies, start+adap->timeout)) {
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return -ETIMEDOUT;
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}
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cond_resched();
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}
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DEBSTAT(printk(KERN_DEBUG "needed %ld jiffies\n", jiffies-start));
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udelay(adap->udelay);
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return 0;
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}
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/* --- other auxiliary functions -------------------------------------- */
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static void i2c_start(struct i2c_algo_bit_data *adap)
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{
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/* assert: scl, sda are high */
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DEBPROTO(printk("S "));
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sdalo(adap);
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scllo(adap);
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}
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static void i2c_repstart(struct i2c_algo_bit_data *adap)
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{
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/* scl, sda may not be high */
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DEBPROTO(printk(" Sr "));
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setsda(adap,1);
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sclhi(adap);
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udelay(adap->udelay);
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sdalo(adap);
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scllo(adap);
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}
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static void i2c_stop(struct i2c_algo_bit_data *adap)
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{
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DEBPROTO(printk("P\n"));
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/* assert: scl is low */
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sdalo(adap);
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sclhi(adap);
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sdahi(adap);
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}
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/* send a byte without start cond., look for arbitration,
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check ackn. from slave */
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/* returns:
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* 1 if the device acknowledged
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* 0 if the device did not ack
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* -ETIMEDOUT if an error occurred (while raising the scl line)
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*/
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static int i2c_outb(struct i2c_adapter *i2c_adap, char c)
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{
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int i;
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int sb;
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int ack;
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struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
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/* assert: scl is low */
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for ( i=7 ; i>=0 ; i-- ) {
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sb = c & ( 1 << i );
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setsda(adap,sb);
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udelay(adap->udelay);
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DEBPROTO(printk(KERN_DEBUG "%d",sb!=0));
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if (sclhi(adap)<0) { /* timed out */
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sdahi(adap); /* we don't want to block the net */
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DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x, timeout at bit #%d\n", c&0xff, i));
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return -ETIMEDOUT;
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};
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/* do arbitration here:
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* if ( sb && ! getsda(adap) ) -> ouch! Get out of here.
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*/
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setscl(adap, 0 );
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udelay(adap->udelay);
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}
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sdahi(adap);
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if (sclhi(adap)<0){ /* timeout */
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DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x, timeout at ack\n", c&0xff));
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return -ETIMEDOUT;
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};
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/* read ack: SDA should be pulled down by slave */
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ack=getsda(adap); /* ack: sda is pulled low ->success. */
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DEB2(printk(KERN_DEBUG " i2c_outb: 0x%02x , getsda() = %d\n", c & 0xff, ack));
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DEBPROTO( printk(KERN_DEBUG "[%2.2x]",c&0xff) );
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DEBPROTO(if (0==ack){ printk(KERN_DEBUG " A ");} else printk(KERN_DEBUG " NA ") );
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scllo(adap);
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return 0==ack; /* return 1 if device acked */
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/* assert: scl is low (sda undef) */
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}
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static int i2c_inb(struct i2c_adapter *i2c_adap)
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{
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/* read byte via i2c port, without start/stop sequence */
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/* acknowledge is sent in i2c_read. */
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int i;
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unsigned char indata=0;
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struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
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/* assert: scl is low */
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sdahi(adap);
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for (i=0;i<8;i++) {
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if (sclhi(adap)<0) { /* timeout */
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DEB2(printk(KERN_DEBUG " i2c_inb: timeout at bit #%d\n", 7-i));
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return -ETIMEDOUT;
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};
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indata *= 2;
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if ( getsda(adap) )
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indata |= 0x01;
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scllo(adap);
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}
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/* assert: scl is low */
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DEB2(printk(KERN_DEBUG "i2c_inb: 0x%02x\n", indata & 0xff));
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DEBPROTO(printk(KERN_DEBUG " 0x%02x", indata & 0xff));
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return (int) (indata & 0xff);
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}
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/*
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* Sanity check for the adapter hardware - check the reaction of
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* the bus lines only if it seems to be idle.
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*/
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static int test_bus(struct i2c_algo_bit_data *adap, char* name) {
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int scl,sda;
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if (adap->getscl==NULL)
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printk(KERN_INFO "i2c-algo-bit.o: Testing SDA only, "
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"SCL is not readable.\n");
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sda=getsda(adap);
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scl=(adap->getscl==NULL?1:getscl(adap));
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printk(KERN_DEBUG "i2c-algo-bit.o: (0) scl=%d, sda=%d\n",scl,sda);
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if (!scl || !sda ) {
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printk(KERN_WARNING "i2c-algo-bit.o: %s seems to be busy.\n", name);
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goto bailout;
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}
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sdalo(adap);
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sda=getsda(adap);
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scl=(adap->getscl==NULL?1:getscl(adap));
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printk(KERN_DEBUG "i2c-algo-bit.o: (1) scl=%d, sda=%d\n",scl,sda);
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if ( 0 != sda ) {
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printk(KERN_WARNING "i2c-algo-bit.o: SDA stuck high!\n");
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goto bailout;
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}
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if ( 0 == scl ) {
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printk(KERN_WARNING "i2c-algo-bit.o: SCL unexpected low "
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"while pulling SDA low!\n");
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goto bailout;
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}
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sdahi(adap);
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sda=getsda(adap);
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scl=(adap->getscl==NULL?1:getscl(adap));
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printk(KERN_DEBUG "i2c-algo-bit.o: (2) scl=%d, sda=%d\n",scl,sda);
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if ( 0 == sda ) {
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printk(KERN_WARNING "i2c-algo-bit.o: SDA stuck low!\n");
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goto bailout;
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}
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if ( 0 == scl ) {
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printk(KERN_WARNING "i2c-algo-bit.o: SCL unexpected low "
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"while pulling SDA high!\n");
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goto bailout;
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}
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scllo(adap);
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sda=getsda(adap);
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scl=(adap->getscl==NULL?0:getscl(adap));
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printk(KERN_DEBUG "i2c-algo-bit.o: (3) scl=%d, sda=%d\n",scl,sda);
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if ( 0 != scl ) {
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printk(KERN_WARNING "i2c-algo-bit.o: SCL stuck high!\n");
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goto bailout;
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}
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if ( 0 == sda ) {
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printk(KERN_WARNING "i2c-algo-bit.o: SDA unexpected low "
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"while pulling SCL low!\n");
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goto bailout;
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}
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sclhi(adap);
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sda=getsda(adap);
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scl=(adap->getscl==NULL?1:getscl(adap));
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printk(KERN_DEBUG "i2c-algo-bit.o: (4) scl=%d, sda=%d\n",scl,sda);
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if ( 0 == scl ) {
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printk(KERN_WARNING "i2c-algo-bit.o: SCL stuck low!\n");
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goto bailout;
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}
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if ( 0 == sda ) {
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printk(KERN_WARNING "i2c-algo-bit.o: SDA unexpected low "
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"while pulling SCL high!\n");
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goto bailout;
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}
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printk(KERN_INFO "i2c-algo-bit.o: %s passed test.\n",name);
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return 0;
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bailout:
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sdahi(adap);
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sclhi(adap);
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return -ENODEV;
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}
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/* ----- Utility functions
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*/
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/* try_address tries to contact a chip for a number of
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* times before it gives up.
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* return values:
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* 1 chip answered
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* 0 chip did not answer
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* -x transmission error
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*/
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static inline int try_address(struct i2c_adapter *i2c_adap,
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unsigned char addr, int retries)
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{
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struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
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int i,ret = -1;
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for (i=0;i<=retries;i++) {
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ret = i2c_outb(i2c_adap,addr);
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if (ret==1)
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break; /* success! */
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i2c_stop(adap);
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udelay(5/*adap->udelay*/);
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if (i==retries) /* no success */
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break;
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i2c_start(adap);
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udelay(adap->udelay);
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}
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DEB2(if (i)
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printk(KERN_DEBUG "i2c-algo-bit.o: Used %d tries to %s client at 0x%02x : %s\n",
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i+1, addr & 1 ? "read" : "write", addr>>1,
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ret==1 ? "success" : ret==0 ? "no ack" : "failed, timeout?" )
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);
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return ret;
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}
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static int sendbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
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{
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struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
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char c;
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const char *temp = msg->buf;
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int count = msg->len;
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unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
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int retval;
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int wrcount=0;
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while (count > 0) {
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c = *temp;
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DEB2(dev_dbg(&i2c_adap->dev, "sendbytes: writing %2.2X\n", c&0xff));
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retval = i2c_outb(i2c_adap,c);
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if ((retval>0) || (nak_ok && (retval==0))) { /* ok or ignored NAK */
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count--;
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temp++;
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wrcount++;
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} else { /* arbitration or no acknowledge */
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dev_err(&i2c_adap->dev, "sendbytes: error - bailout.\n");
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i2c_stop(adap);
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return (retval<0)? retval : -EFAULT;
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/* got a better one ?? */
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}
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#if 0
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/* from asm/delay.h */
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__delay(adap->mdelay * (loops_per_sec / 1000) );
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#endif
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}
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return wrcount;
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}
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static inline int readbytes(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
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{
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int inval;
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int rdcount=0; /* counts bytes read */
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struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
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char *temp = msg->buf;
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int count = msg->len;
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while (count > 0) {
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inval = i2c_inb(i2c_adap);
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/*printk("%#02x ",inval); if ( ! (count % 16) ) printk("\n"); */
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if (inval>=0) {
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*temp = inval;
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rdcount++;
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} else { /* read timed out */
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printk(KERN_ERR "i2c-algo-bit.o: readbytes: i2c_inb timed out.\n");
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break;
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}
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temp++;
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count--;
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if (msg->flags & I2C_M_NO_RD_ACK)
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continue;
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if ( count > 0 ) { /* send ack */
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sdalo(adap);
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DEBPROTO(printk(" Am "));
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} else {
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sdahi(adap); /* neg. ack on last byte */
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DEBPROTO(printk(" NAm "));
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}
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if (sclhi(adap)<0) { /* timeout */
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sdahi(adap);
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printk(KERN_ERR "i2c-algo-bit.o: readbytes: Timeout at ack\n");
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return -ETIMEDOUT;
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};
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scllo(adap);
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sdahi(adap);
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}
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return rdcount;
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}
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/* doAddress initiates the transfer by generating the start condition (in
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* try_address) and transmits the address in the necessary format to handle
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* reads, writes as well as 10bit-addresses.
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* returns:
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* 0 everything went okay, the chip ack'ed, or IGNORE_NAK flag was set
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* -x an error occurred (like: -EREMOTEIO if the device did not answer, or
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* -ETIMEDOUT, for example if the lines are stuck...)
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*/
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static inline int bit_doAddress(struct i2c_adapter *i2c_adap, struct i2c_msg *msg)
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{
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unsigned short flags = msg->flags;
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unsigned short nak_ok = msg->flags & I2C_M_IGNORE_NAK;
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struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
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unsigned char addr;
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int ret, retries;
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retries = nak_ok ? 0 : i2c_adap->retries;
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if ( (flags & I2C_M_TEN) ) {
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/* a ten bit address */
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addr = 0xf0 | (( msg->addr >> 7) & 0x03);
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DEB2(printk(KERN_DEBUG "addr0: %d\n",addr));
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/* try extended address code...*/
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ret = try_address(i2c_adap, addr, retries);
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if ((ret != 1) && !nak_ok) {
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printk(KERN_ERR "died at extended address code.\n");
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return -EREMOTEIO;
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}
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/* the remaining 8 bit address */
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ret = i2c_outb(i2c_adap,msg->addr & 0x7f);
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if ((ret != 1) && !nak_ok) {
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/* the chip did not ack / xmission error occurred */
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printk(KERN_ERR "died at 2nd address code.\n");
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return -EREMOTEIO;
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}
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if ( flags & I2C_M_RD ) {
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i2c_repstart(adap);
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/* okay, now switch into reading mode */
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addr |= 0x01;
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ret = try_address(i2c_adap, addr, retries);
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if ((ret!=1) && !nak_ok) {
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printk(KERN_ERR "died at extended address code.\n");
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return -EREMOTEIO;
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}
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}
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} else { /* normal 7bit address */
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addr = ( msg->addr << 1 );
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if (flags & I2C_M_RD )
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addr |= 1;
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if (flags & I2C_M_REV_DIR_ADDR )
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addr ^= 1;
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ret = try_address(i2c_adap, addr, retries);
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if ((ret!=1) && !nak_ok)
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return -EREMOTEIO;
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}
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return 0;
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}
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static int bit_xfer(struct i2c_adapter *i2c_adap,
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struct i2c_msg msgs[], int num)
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{
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struct i2c_msg *pmsg;
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struct i2c_algo_bit_data *adap = i2c_adap->algo_data;
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|
|
|
int i,ret;
|
|
unsigned short nak_ok;
|
|
|
|
i2c_start(adap);
|
|
for (i=0;i<num;i++) {
|
|
pmsg = &msgs[i];
|
|
nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
|
|
if (!(pmsg->flags & I2C_M_NOSTART)) {
|
|
if (i) {
|
|
i2c_repstart(adap);
|
|
}
|
|
ret = bit_doAddress(i2c_adap, pmsg);
|
|
if ((ret != 0) && !nak_ok) {
|
|
DEB2(printk(KERN_DEBUG "i2c-algo-bit.o: NAK from device addr %2.2x 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);
|
|
DEB2(printk(KERN_DEBUG "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);
|
|
DEB2(printk(KERN_DEBUG "i2c-algo-bit.o: wrote %d bytes.\n",ret));
|
|
if (ret < pmsg->len ) {
|
|
return (ret<0) ? ret : -EREMOTEIO;
|
|
}
|
|
}
|
|
}
|
|
i2c_stop(adap);
|
|
return num;
|
|
}
|
|
|
|
static u32 bit_func(struct i2c_adapter *adap)
|
|
{
|
|
return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL |
|
|
I2C_FUNC_10BIT_ADDR | I2C_FUNC_PROTOCOL_MANGLING;
|
|
}
|
|
|
|
|
|
/* -----exported algorithm data: ------------------------------------- */
|
|
|
|
static struct i2c_algorithm i2c_bit_algo = {
|
|
.name = "Bit-shift algorithm",
|
|
.id = I2C_ALGO_BIT,
|
|
.master_xfer = bit_xfer,
|
|
.functionality = bit_func,
|
|
};
|
|
|
|
/*
|
|
* registering functions to load algorithms at runtime
|
|
*/
|
|
int i2c_bit_add_bus(struct i2c_adapter *adap)
|
|
{
|
|
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(dev_dbg(&adap->dev, "hw routines registered.\n"));
|
|
|
|
/* 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 */
|
|
|
|
i2c_add_adapter(adap);
|
|
return 0;
|
|
}
|
|
|
|
|
|
int i2c_bit_del_bus(struct i2c_adapter *adap)
|
|
{
|
|
return i2c_del_adapter(adap);
|
|
}
|
|
|
|
EXPORT_SYMBOL(i2c_bit_add_bus);
|
|
EXPORT_SYMBOL(i2c_bit_del_bus);
|
|
|
|
MODULE_AUTHOR("Simon G. Vogl <simon@tk.uni-linz.ac.at>");
|
|
MODULE_DESCRIPTION("I2C-Bus bit-banging algorithm");
|
|
MODULE_LICENSE("GPL");
|
|
|
|
module_param(bit_test, bool, 0);
|
|
module_param(i2c_debug, int, S_IRUGO | S_IWUSR);
|
|
|
|
MODULE_PARM_DESC(bit_test, "Test the lines of the bus to see if it is stuck");
|
|
MODULE_PARM_DESC(i2c_debug,
|
|
"debug level - 0 off; 1 normal; 2,3 more verbose; 9 bit-protocol");
|
|
|