475 lines
12 KiB
C
475 lines
12 KiB
C
/* ------------------------------------------------------------------------- */
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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 "wait.h"
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#include "i2c.h"
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#include "i2c-algo-bit.h"
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#ifndef NULL
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#define NULL ((void *)0)
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#endif
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// #define DEBUG
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#include "debug.h"
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extern void start_timeout(void);
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extern int end_timeout(long msec);
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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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wait_us(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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wait_us(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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wait_us(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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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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{
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wait_us(adap->udelay);
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return 0;
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}
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start_timeout();
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while (! getscl(adap))
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{
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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 (end_timeout((long)adap->timeout))
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return -110;
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}
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wait_us(adap->udelay);
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return 0;
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}
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/* --- other auxiliary functions -------------------------------------- */
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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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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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setsda(adap, 1);
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sclhi(adap);
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wait_us(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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/* 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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/*
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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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*
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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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{
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sb = c & (1 << i);
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setsda(adap,sb);
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wait_us(adap->udelay);
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if (sclhi(adap) < 0)
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{
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/* timed out */
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sdahi(adap); /* we don't want to block the net */
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#ifdef DEBUG
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dbg("ETIMEDOUT\r\n");
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#endif
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return -110;
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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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wait_us(adap->udelay);
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}
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sdahi(adap);
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if(sclhi(adap)<0)
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{
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/* timeout */
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dbg("ETIMEDOUT\r\n");
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return -110;
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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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scllo(adap);
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dbg("0x%02x, ack=0x%02x\r\n", (unsigned long)(c & 0xff), ack);
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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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{
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if (sclhi(adap) < 0)
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{
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/* timeout */
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dbg("i2c_inb TIMEDOUT\r\n");
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return -110;
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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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dbg("0x%02x\r\n", (unsigned long)(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)
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{
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int scl, sda;
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sda = getsda(adap);
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scl = (adap->getscl == NULL ? 1 : getscl(adap));
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if (!scl || !sda )
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goto bailout;
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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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if (sda !=0 || scl == 0)
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goto bailout;
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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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if (sda == 0 || scl ==0)
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goto bailout;
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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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if (scl !=0 || sda == 0)
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goto bailout;
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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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if (scl == 0 || sda ==0)
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goto bailout;
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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 -110;
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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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{
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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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wait_us(5);
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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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wait_us(adap->udelay);
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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 = (const char *)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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{
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c = *temp;
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retval = i2c_outb(i2c_adap,c);
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if ((retval > 0) || (nak_ok && (retval==0)))
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{ /* ok or ignored NAK */
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count--;
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temp++;
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wrcount++;
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}
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else
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{ /* arbitration or no acknowledge */
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i2c_stop(adap);
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return (retval < 0)? retval : -110;
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/* got a better one ?? */
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}
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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 = (char *)msg->buf;
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int count = msg->len;
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while(count > 0)
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{
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inval = i2c_inb(i2c_adap);
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if (inval >= 0)
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{
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*temp = inval;
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rdcount++;
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}
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else
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/* read timed out */
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break;
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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)
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/* send ack */
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sdalo(adap);
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else
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sdahi(adap); /* neg. ack on last byte */
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if (sclhi(adap) < 0)
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{
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/* timeout */
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sdahi(adap);
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return -1;
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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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{
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/* a ten bit address */
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addr = 0xf0 | (( msg->addr >> 7) & 0x03);
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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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return -1;
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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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return -1;
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if (flags & I2C_M_RD)
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{
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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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return -1;
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}
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}
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else
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{ /* 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 -1;
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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, 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;
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unsigned short nak_ok;
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i2c_start(adap);
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for(i=0;i<num;i++)
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{
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pmsg = &msgs[i];
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nak_ok = pmsg->flags & I2C_M_IGNORE_NAK;
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if(!(pmsg->flags & I2C_M_NOSTART))
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{
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if (i)
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i2c_repstart(adap);
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ret = bit_doAddress(i2c_adap, pmsg);
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if ((ret != 0) && !nak_ok)
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return (ret < 0) ? ret : -1;
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}
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if(pmsg->flags & I2C_M_RD )
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{
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/* read bytes into buffer*/
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ret = readbytes(i2c_adap, pmsg);
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if(ret < pmsg->len)
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return (ret < 0)? ret : -1;
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}
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else
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{
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/* write bytes from buffer */
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ret = sendbytes(i2c_adap, pmsg);
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if (ret < pmsg->len )
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return (ret < 0) ? ret : -1;
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}
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}
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i2c_stop(adap);
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return num;
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}
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/* -----exported algorithm data: ------------------------------------- */
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static struct i2c_algorithm i2c_bit_algo = {
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.master_xfer = bit_xfer,
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};
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/*
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* registering functions to load algorithms at runtime
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*/
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int i2c_bit_add_bus(struct i2c_adapter *adap)
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{
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struct i2c_algo_bit_data *bit_adap = adap->algo_data;
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if (1)
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{
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int ret = test_bus(bit_adap);
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if (ret < 0)
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return -1;
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}
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/* register new adapter to i2c module... */
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adap->algo = &i2c_bit_algo;
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adap->timeout = 10; /* default values, should */
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adap->retries = 3; /* be replaced by defines */
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return 0;
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}
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int i2c_bit_del_bus(struct i2c_adapter *adap)
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{
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return 0;
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}
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/* ----------------------------------------------------
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* the functional interface to the i2c busses.
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* ----------------------------------------------------
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*/
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int i2c_transfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
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{
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int ret;
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if (adap->algo->master_xfer)
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{
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ret = adap->algo->master_xfer(adap, msgs, num);
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return ret;
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}
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else
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return -1;
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}
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