i2c-algo-ibm_ocp.c

I2C总线LINUX驱动程序

/*
   -------------------------------------------------------------------------
   i2c-algo-ibm_ocp.c i2c driver algorithms for IBM PPC 405 adapters	    
   -------------------------------------------------------------------------
      
   Ian DaSilva, MontaVista Software, Inc.
   [e-mail] or [e-mail]

   Copyright 2000 MontaVista Software Inc.

   Changes made to support the IIC peripheral on the IBM PPC 405


   ---------------------------------------------------------------------------
   This file was highly leveraged from i2c-algo-pcf.c, which was created
   by Simon G. Vogl and Hans Berglund:


     Copyright (C) 1995-1997 Simon G. Vogl
                   1998-2000 Hans Berglund

   With some changes from Ky鰏ti M鋖kki <[e-mail]> and 
   Frodo Looijaard <[e-mail]> ,and also from Martin Bailey
   <[e-mail]>


    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.
   ---------------------------------------------------------------------------

   History: 01/20/12 - Armin
   	[e-mail]
   	ported up to 2.4.16+	

   Version 02/03/25 - Armin
       converted to ocp format
       removed commented out or #if 0 code
       added G閞ard Basler's fix to iic_combined_transaction() such that it 
       returns the number of successfully completed transfers .
*/


#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/sched.h>
#include "i2c.h"
#include "i2c-algo-ibm_ocp.h"
#include <asm/ocp.h>


/* ----- global defines ----------------------------------------------- */
#define DEB(x) if (i2c_debug>=1) x
#define DEB2(x) if (i2c_debug>=2) x
#define DEB3(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 */
#define DEF_TIMEOUT 5


/* ----- global variables ---------------------------------------------	*/


/* module parameters:
 */
static int i2c_debug=0;

/* --- setting states on the bus with the right timing: ---------------	*/

#define iic_outb(adap, reg, val) adap->setiic(adap->data, (int) &(reg), val)
#define iic_inb(adap, reg) adap->getiic(adap->data, (int) &(reg))

#define IICO_I2C_SDAHIGH	0x0780
#define IICO_I2C_SDALOW		0x0781
#define IICO_I2C_SCLHIGH	0x0782
#define IICO_I2C_SCLLOW		0x0783
#define IICO_I2C_LINEREAD	0x0784

#define IIC_SINGLE_XFER		0
#define IIC_COMBINED_XFER	1

#define IIC_ERR_LOST_ARB        -2
#define IIC_ERR_INCOMPLETE_XFR  -3
#define IIC_ERR_NACK            -1

/* --- other auxiliary functions --------------------------------------	*/


//
// Description: Puts this process to sleep for a period equal to timeout 
//
static inline void iic_sleep(unsigned long timeout)
{
	schedule_timeout( timeout * HZ);
}


//
// Description: This performs the IBM PPC 405 IIC initialization sequence
// as described in the PPC405GP data book.
//
static int iic_init (struct i2c_algo_iic_data *adap)
{
	struct iic_regs *iic;	
	struct iic_ibm *adap_priv_data = adap->data;
	unsigned short	retval;
	iic = (struct iic_regs *) adap_priv_data->iic_base;

        /* Clear master low master address */
        iic_outb(adap,iic->lmadr, 0);

        /* Clear high master address */
        iic_outb(adap,iic->hmadr, 0);

        /* Clear low slave address */
        iic_outb(adap,iic->lsadr, 0);

        /* Clear high slave address */
        iic_outb(adap,iic->hsadr, 0);

        /* Clear status */
        iic_outb(adap,iic->sts, 0x0a);

        /* Clear extended status */
        iic_outb(adap,iic->extsts, 0x8f);

        /* Set clock division */
        iic_outb(adap,iic->clkdiv, 0x04);

	retval = iic_inb(adap, iic->clkdiv);
	DEB(printk("iic_init: CLKDIV register = %x\n", retval));

        /* Enable interrupts on Requested Master Transfer Complete */
        iic_outb(adap,iic->intmsk, 0x01);

        /* Clear transfer count */
        iic_outb(adap,iic->xfrcnt, 0x0);

        /* Clear extended control and status */
        iic_outb(adap,iic->xtcntlss, 0xf0);

        /* Set mode control (flush master data buf, enable hold SCL, exit */
        /* unknown state.                                                 */
        iic_outb(adap,iic->mdcntl, 0x47);

        /* Clear control register */
        iic_outb(adap,iic->cntl, 0x0);

        DEB2(printk(KERN_DEBUG "iic_init: Initialized IIC on PPC 405\n"));
        return 0;
}


//
// Description: After we issue a transaction on the IIC bus, this function
// is called.  It puts this process to sleep until we get an interrupt from
// from the controller telling us that the transaction we requested in complete.
//
static int wait_for_pin(struct i2c_algo_iic_data *adap, int *status) 
{

	int timeout = DEF_TIMEOUT;
	int retval;
	struct iic_regs *iic;
	struct iic_ibm *adap_priv_data = adap->data;
	iic = (struct iic_regs *) adap_priv_data->iic_base;


	*status = iic_inb(adap, iic->sts);
#ifndef STUB_I2C

	while (timeout-- && (*status & 0x01)) {
	   adap->waitforpin(adap->data);
	   *status = iic_inb(adap, iic->sts);
	}
#endif
	if (timeout <= 0) {
	   /* Issue stop signal on the bus, and force an interrupt */
           retval = iic_inb(adap, iic->cntl);
           iic_outb(adap, iic->cntl, retval | 0x80);
           /* Clear status register */
	   iic_outb(adap, iic->sts, 0x0a);
	   /* Exit unknown bus state */
	   retval = iic_inb(adap, iic->mdcntl);
	   iic_outb(adap, iic->mdcntl, (retval | 0x02));

	   // Check the status of the controller.  Does it still see a
	   // pending transfer, even though we've tried to stop any
	   // ongoing transaction?
           retval = iic_inb(adap, iic->sts);
           retval = retval & 0x01;
           if(retval) {
	      // The iic controller is hosed.  It is not responding to any
	      // of our commands.  We have already tried to force it into
	      // a known state, but it has not worked.  Our only choice now
	      // is a soft reset, which will clear all registers, and force
	      // us to re-initialize the controller.
	      /* Soft reset */
              iic_outb(adap, iic->xtcntlss, 0x01);
              udelay(500);
              iic_init(adap);
	      /* Is the pending transfer bit in the sts reg finally cleared? */
              retval = iic_inb(adap, iic->sts);
              retval = retval & 0x01;
              if(retval) {
                 printk(KERN_CRIT "The IIC Controller is hosed.  A processor reset is required\n");
              }
	      // For some reason, even though the interrupt bit in this
	      // register was set during iic_init, it didn't take.  We
	      // need to set it again.  Don't ask me why....this is just what
	      // I saw when testing timeouts.
              iic_outb(adap, iic->intmsk, 0x01);
           }
	   return(-1);
	}
	else
	   return(0);
}


//------------------------------------
// Utility functions
//


//
// Description: Look at the status register to see if there was an error
// in the requested transaction.  If there is, look at the extended status
// register and determine the exact cause.
//
int analyze_status(struct i2c_algo_iic_data *adap, int *error_code)
{
   int ret;
   struct iic_regs *iic;
   struct iic_ibm *adap_priv_data = adap->data;
   iic = (struct iic_regs *) adap_priv_data->iic_base;

	
   ret = iic_inb(adap, iic->sts);
   if(ret & 0x04) {
      // Error occurred
      ret = iic_inb(adap, iic->extsts);
      if(ret & 0x04) {
         // Lost arbitration
         *error_code =  IIC_ERR_LOST_ARB;
      }
      if(ret & 0x02) {
         // Incomplete transfer
         *error_code = IIC_ERR_INCOMPLETE_XFR;
      }
      if(ret & 0x01) {
         // Master transfer aborted by a NACK during the transfer of the 
	 // address byte
         *error_code = IIC_ERR_NACK;
      }
      return -1;
   }
   return 0;
}


//
// Description: This function is called by the upper layers to do the
// grunt work for a master send transaction
//
static int iic_sendbytes(struct i2c_adapter *i2c_adap,const char *buf,
                         int count, int xfer_flag)
{
	struct iic_regs *iic;
	struct i2c_algo_iic_data *adap = i2c_adap->algo_data;
	struct iic_ibm *adap_priv_data = adap->data;
	int wrcount, status, timeout;
	int loops, remainder, i, j;
	int ret, error_code;
  	iic = (struct iic_regs *) adap_priv_data->iic_base;

 
	if( count == 0 ) return 0;
	wrcount = 0;
	loops =  count / 4;
	remainder = count % 4;

	if((loops > 1) && (remainder == 0)) {
	   for(i=0; i<(loops-1); i++) {
       	      //
   	      // Write four bytes to master data buffer
	      //
	      for(j=0; j<4; j++) {
   	         iic_outb(adap, iic->mdbuf, 
	         buf[wrcount++]);
  	      }
	      //
	      // Issue command to IICO device to begin transmission
	      //
	      iic_outb(adap, iic->cntl, 0x35);
	      //
	      // Wait for transmission to complete.  When it does, 
	      //loop to the top of the for statement and write the 
	      // next four bytes.
	      //
	      timeout = wait_for_pin(adap, &status);
	      if(timeout < 0) {
	         //
	         // Error handling
	         //
                 //printk(KERN_ERR "Error: write timeout\n");
                 return wrcount;
	      }
	      ret = analyze_status(adap, &error_code);
	      if(ret < 0) {
                 if(error_code == IIC_ERR_INCOMPLETE_XFR) {
                    // Return the number of bytes transferred
                    ret = iic_inb(adap, iic->xfrcnt);
                    ret = ret & 0x07;
                    return (wrcount-4+ret);
                 }
                 else return error_code;
              }
           }
	}
	else if((loops >= 1) && (remainder > 0)){
	   //printk(KERN_DEBUG "iic_sendbytes: (loops >= 1)\n");
	   for(i=0; i<loops; i++) {
              //
              // Write four bytes to master data buffer
              //
              for(j=0; j<4; j++) {
                 iic_outb(adap, iic->mdbuf,
                 buf[wrcount++]);
              }
              //
              // Issue command to IICO device to begin transmission
              //
              iic_outb(adap, iic->cntl, 0x35);
              //
              // Wait for transmission to complete.  When it does,
              //loop to the top of the for statement and write the
              // next four bytes.
              //
              timeout = wait_for_pin(adap, &status);
              if(timeout < 0) {
                 //
                 // Error handling
                 //
                 //printk(KERN_ERR "Error: write timeout\n");
                 return wrcount;
              }
              ret = analyze_status(adap, &error_code);
              if(ret < 0) {
                 if(error_code == IIC_ERR_INCOMPLETE_XFR) {
                    // Return the number of bytes transferred
                    ret = iic_inb(adap, iic->xfrcnt);
                    ret = ret & 0x07;
                    return (wrcount-4+ret);
                 }
                 else return error_code;
              }
           }
        }

	//printk(KERN_DEBUG "iic_sendbytes: expedite write\n");
	if(remainder == 0) remainder = 4;
	// remainder = remainder - 1;
	//
	// Write the remaining bytes (less than or equal to 4)
	//
	for(i=0; i<remainder; i++) {
	   iic_outb(adap, iic->mdbuf, buf[wrcount++]);
	   //printk(KERN_DEBUG "iic_sendbytes:  data transferred = %x, wrcount = %d\n", buf[wrcount-1], (wrcount-1));
	}
        //printk(KERN_DEBUG "iic_sendbytes: Issuing write\n");

        if(xfer_flag == IIC_COMBINED_XFER) {
           iic_outb(adap, iic->cntl, (0x09 | ((remainder-1) << 4)));
        }
	else {
           iic_outb(adap, iic->cntl, (0x01 | ((remainder-1) << 4)));
        }
	DEB2(printk(KERN_DEBUG "iic_sendbytes: Waiting for interrupt\n"));
	timeout = wait_for_pin(adap, &status);
        if(timeout < 0) {
       	   //
           // Error handling
           //
           //printk(KERN_ERR "Error: write timeout\n");
           return wrcount;
        }
        ret = analyze_status(adap, &error_code);
        if(ret < 0) {
           if(error_code == IIC_ERR_INCOMPLETE_XFR) {
              // Return the number of bytes transferred
              ret = iic_inb(adap, iic->xfrcnt);
              ret = ret & 0x07;
              return (wrcount-4+ret);
           }
           else return error_code;
        }
	DEB2(printk(KERN_DEBUG "iic_sendbytes: Got interrupt\n"));
	return wrcount;
}


//
// Description: Called by the upper layers to do the grunt work for
// a master read transaction.
//
static int iic_readbytes(struct i2c_adapter *i2c_adap, char *buf, int count, int xfer_type)
{
	struct iic_regs *iic;
	int rdcount=0, i, status, timeout;
	struct i2c_algo_iic_data *adap = i2c_adap->algo_data;
	struct iic_ibm *adap_priv_data = adap->data;
	int loops, remainder, j;
        int ret, error_code;
	iic = (struct iic_regs *) adap_priv_data->iic_base;

	if(count == 0) return 0;
	loops = count / 4;
	remainder = count % 4;

	//printk(KERN_DEBUG "iic_readbytes: loops = %d, remainder = %d\n", loops, remainder);

	if((loops > 1) && (remainder == 0)) {
	//printk(KERN_DEBUG "iic_readbytes: (loops > 1) && (remainder == 0)\n");
	   for(i=0; i<(loops-1); i++) {
	      //
              // Issue command to begin master read (4 bytes maximum)
              //
	      //printk(KERN_DEBUG "--->Issued read command\n");
	      iic_outb(adap, iic->cntl, 0x37);
	      //
              // Wait for transmission to complete.  When it does,
              // loop to the top of the for statement and write the
              // next four bytes.
              //
	      //printk(KERN_DEBUG "--->Waiting for interrupt\n");
              timeout = wait_for_pin(adap, &status);