i2c-ite.c

/*
   -------------------------------------------------------------------------
   i2c-adap-ite.c i2c-hw access for the IIC peripheral on the ITE MIPS system
   -------------------------------------------------------------------------
   Hai-Pao Fan, MontaVista Software, Inc.
   hpfan@mvista.com or source@mvista.com

   Copyright 2001 MontaVista Software Inc.

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

 
     Copyright (C) 1995-97 Simon G. Vogl
                   1998-99 Hans Berglund

    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 Kysti Mlkki <kmalkki@cc.hut.fi> and even
   Frodo Looijaard <frodol@dds.nl> */

#include <linux/kernel.h>
#include <linux/ioport.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/wait.h>
#include <asm/irq.h>
#include <asm/io.h>

#include <linux/i2c.h>
#include <linux/i2c-algo-ite.h>
#include <linux/i2c-adap-ite.h>
#include "../i2c-ite.h"

#define DEFAULT_BASE  0x14014030
#define ITE_IIC_IO_SIZE	0x40
#define DEFAULT_IRQ   0
#define DEFAULT_CLOCK 0x1b0e	/* default 16MHz/(27+14) = 400KHz */
#define DEFAULT_OWN   0x55

static int base;
static int irq;
static int clock;
static int own;

static struct iic_ite gpi;
static wait_queue_head_t iic_wait;
static int iic_pending;
static spinlock_t lock;

/* ----- local functions ----------------------------------------------	*/

static void iic_ite_setiic(void *data, int ctl, short val)
{
        unsigned long j = jiffies + 10;

	pr_debug(" Write 0x%02x to 0x%x\n",(unsigned short)val, ctl&0xff);
#ifdef DEBUG
	while (time_before(jiffies, j))
		schedule();
#endif
	outw(val,ctl);
}

static short iic_ite_getiic(void *data, int ctl)
{
	short val;

	val = inw(ctl);
	pr_debug("Read 0x%02x from 0x%x\n",(unsigned short)val, ctl&0xff);
	return (val);
}

/* Return our slave address.  This is the address
 * put on the I2C bus when another master on the bus wants to address us
 * as a slave
 */
static int iic_ite_getown(void *data)
{
	return (gpi.iic_own);
}


static int iic_ite_getclock(void *data)
{
	return (gpi.iic_clock);
}


/* Put this process to sleep.  We will wake up when the
 * IIC controller interrupts.
 */
static void iic_ite_waitforpin(void) {
   DEFINE_WAIT(wait);
   int timeout = 2;
   unsigned long flags;

   /* If interrupts are enabled (which they are), then put the process to
    * sleep.  This process will be awakened by two events -- either the
    * the IIC peripheral interrupts or the timeout expires. 
    * If interrupts are not enabled then delay for a reasonable amount 
    * of time and return.
    */
   if (gpi.iic_irq > 0) {
	spin_lock_irqsave(&lock, flags);
	if (iic_pending == 0) {
		spin_unlock_irqrestore(&lock, flags);
		prepare_to_wait(&iic_wait, &wait, TASK_INTERRUPTIBLE);
		if (schedule_timeout(timeout*HZ)) {
			spin_lock_irqsave(&lock, flags);
			if (iic_pending == 1) {
				iic_pending = 0;
			}
			spin_unlock_irqrestore(&lock, flags);
		}
		finish_wait(&iic_wait, &wait);
	} else {
		iic_pending = 0;
		spin_unlock_irqrestore(&lock, flags);
	}
   } else {
      udelay(100);
   }
}


static irqreturn_t iic_ite_handler(int this_irq, void *dev_id)
{
	spin_lock(&lock);
	iic_pending = 1;
	spin_unlock(&lock);

	wake_up_interruptible(&iic_wait);

	return IRQ_HANDLED;
}


/* Lock the region of memory where I/O registers exist.  Request our
 * interrupt line and register its associated handler.
 */
static int iic_hw_resrc_init(void)
{
	if (!request_region(gpi.iic_base, ITE_IIC_IO_SIZE, "i2c"))
		return -ENODEV;
  
	if (gpi.iic_irq <= 0)
		return 0;

	if (request_irq(gpi.iic_irq, iic_ite_handler, 0, "ITE IIC", 0) < 0)
		gpi.iic_irq = 0;
	else
		enable_irq(gpi.iic_irq);

	return 0;
}


static void iic_ite_release(void)
{
	if (gpi.iic_irq > 0) {
		disable_irq(gpi.iic_irq);
		free_irq(gpi.iic_irq, 0);
	}
	release_region(gpi.iic_base , 2);
}

/* ------------------------------------------------------------------------
 * Encapsulate the above functions in the correct operations structure.
 * This is only done when more than one hardware adapter is supported.
 */
static struct i2c_algo_iic_data iic_ite_data = {
	NULL,
	iic_ite_setiic,
	iic_ite_getiic,
	iic_ite_getown,
	iic_ite_getclock,
	iic_ite_waitforpin,
	80, 80, 100,		/*	waits, timeout */
};

static struct i2c_adapter iic_ite_ops = {
	.owner		= THIS_MODULE,
	.id		= I2C_HW_I_IIC,
	.algo_data	= &iic_ite_data,
	.name		= "ITE IIC adapter",
};

/* Called when the module is loaded.  This function starts the
 * cascade of calls up through the hierarchy of i2c modules (i.e. up to the
 *  algorithm layer and into to the core layer)
 */
static int __init iic_ite_init(void) 
{

	struct iic_ite *piic = &gpi;

	printk(KERN_INFO "Initialize ITE IIC adapter module\n");
	if (base == 0)
		piic->iic_base = DEFAULT_BASE;
	else
		piic->iic_base = base;

	if (irq == 0)
		piic->iic_irq = DEFAULT_IRQ;
	else
		piic->iic_irq = irq;

	if (clock == 0)
		piic->iic_clock = DEFAULT_CLOCK;
	else
		piic->iic_clock = clock;

	if (own == 0)
		piic->iic_own = DEFAULT_OWN;
	else
		piic->iic_own = own;

	iic_ite_data.data = (void *)piic;
	init_waitqueue_head(&iic_wait);
	spin_lock_init(&lock);
	if (iic_hw_resrc_init() == 0) {
		if (i2c_iic_add_bus(&iic_ite_ops) < 0)
			return -ENODEV;
	} else {
		return -ENODEV;
	}
	printk(KERN_INFO " found device at %#x irq %d.\n", 
		piic->iic_base, piic->iic_irq);
	return 0;
}


static void iic_ite_exit(void)
{
	i2c_iic_del_bus(&iic_ite_ops);
        iic_ite_release();
}

/* If modules is NOT defined when this file is compiled, then the MODULE_*
 * macros will resolve to nothing
 */
MODULE_AUTHOR("MontaVista Software <www.mvista.com>");
MODULE_DESCRIPTION("I2C-Bus adapter routines for ITE IIC bus adapter");
MODULE_LICENSE("GPL");

module_param(base, int, 0);
module_param(irq, int, 0);
module_param(clock, int, 0);
module_param(own, int, 0);


/* Called when module is loaded or when kernel is initialized.
 * If MODULES is defined when this file is compiled, then this function will
 * resolve to init_module (the function called when insmod is invoked for a
 * module).  Otherwise, this function is called early in the boot, when the
 * kernel is intialized.  Check out /include/init.h to see how this works.
 */
module_init(iic_ite_init);

/* Resolves to module_cleanup when MODULES is defined. */
module_exit(iic_ite_exit);