/*
   *  i2c-pca-isa.c driver for PCA9564 on ISA boards
   *    Copyright (C) 2004 Arcom Control Systems
   *    Copyright (C) 2008 Pengutronix
   *
   *  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.
   */
  
  #include <linux/kernel.h>
  #include <linux/ioport.h>
  #include <linux/module.h>
  #include <linux/moduleparam.h>
  #include <linux/delay.h>
  #include <linux/jiffies.h>
  #include <linux/init.h>
  #include <linux/interrupt.h>
  #include <linux/wait.h>
  #include <linux/isa.h>
  #include <linux/i2c.h>
  #include <linux/i2c-algo-pca.h>
  #include <linux/io.h>
  
  #include <asm/irq.h>
  
  #define DRIVER "i2c-pca-isa"
  #define IO_SIZE 4
  
  static unsigned long base;
  static int irq = -1;
  
  /* Data sheet recommends 59kHz for 100kHz operation due to variation
   * in the actual clock rate */
  static int clock  = 59000;
  
  static struct i2c_adapter pca_isa_ops;
  static wait_queue_head_t pca_wait;
  
  static void pca_isa_writebyte(void *pd, int reg, int val)
  {
  #ifdef DEBUG_IO
  	static char *names[] = { "T/O", "DAT", "ADR", "CON" };
  	printk(KERN_DEBUG "*** write %s at %#lx <= %#04x
  ", names[reg],
  	       base+reg, val);
  #endif
  	outb(val, base+reg);
  }
  
  static int pca_isa_readbyte(void *pd, int reg)
  {
  	int res = inb(base+reg);
  #ifdef DEBUG_IO
  	{
  		static char *names[] = { "STA", "DAT", "ADR", "CON" };
  		printk(KERN_DEBUG "*** read  %s => %#04x
  ", names[reg], res);
  	}
  #endif
  	return res;
  }
  
  static int pca_isa_waitforcompletion(void *pd)
  {
  	unsigned long timeout;
  	long ret;
  
  	if (irq > -1) {
  		ret = wait_event_timeout(pca_wait,
  				pca_isa_readbyte(pd, I2C_PCA_CON)
  				& I2C_PCA_CON_SI, pca_isa_ops.timeout);
  	} else {
  		/* Do polling */
  		timeout = jiffies + pca_isa_ops.timeout;
  		do {
  			ret = time_before(jiffies, timeout);
  			if (pca_isa_readbyte(pd, I2C_PCA_CON)
  					& I2C_PCA_CON_SI)
  				break;
  			udelay(100);
  		} while (ret);
  	}
  
  	return ret > 0;
  }
  
  static void pca_isa_resetchip(void *pd)
  {
  	/* apparently only an external reset will do it. not a lot can be done */
  	printk(KERN_WARNING DRIVER ": Haven't figured out how to do a reset yet
  ");
  }
  
  static irqreturn_t pca_handler(int this_irq, void *dev_id) {
  	wake_up(&pca_wait);
  	return IRQ_HANDLED;
  }
  
  static struct i2c_algo_pca_data pca_isa_data = {
  	/* .data intentionally left NULL, not needed with ISA */
  	.write_byte		= pca_isa_writebyte,
  	.read_byte		= pca_isa_readbyte,
  	.wait_for_completion	= pca_isa_waitforcompletion,
  	.reset_chip		= pca_isa_resetchip,
  };
  
  static struct i2c_adapter pca_isa_ops = {
  	.owner          = THIS_MODULE,
  	.algo_data	= &pca_isa_data,
  	.name		= "PCA9564/PCA9665 ISA Adapter",
  	.timeout	= HZ,
  };
  
  static int pca_isa_match(struct device *dev, unsigned int id)
  {
  	int match = base != 0;
  
  	if (match) {
  		if (irq <= -1)
  			dev_warn(dev, "Using polling mode (specify irq)
  ");
  	} else
  		dev_err(dev, "Please specify I/O base
  ");
  
  	return match;
  }
  
  static int pca_isa_probe(struct device *dev, unsigned int id)
  {
  	init_waitqueue_head(&pca_wait);
  
  	dev_info(dev, "i/o base %#08lx. irq %d
  ", base, irq);
  
  #ifdef CONFIG_PPC
  	if (check_legacy_ioport(base)) {
  		dev_err(dev, "I/O address %#08lx is not available
  ", base);
  		goto out;
  	}
  #endif
  
  	if (!request_region(base, IO_SIZE, "i2c-pca-isa")) {
  		dev_err(dev, "I/O address %#08lx is in use
  ", base);
  		goto out;
  	}
  
  	if (irq > -1) {
  		if (request_irq(irq, pca_handler, 0, "i2c-pca-isa", &pca_isa_ops) < 0) {
  			dev_err(dev, "Request irq%d failed
  ", irq);
  			goto out_region;
  		}
  	}
  
  	pca_isa_data.i2c_clock = clock;
  	if (i2c_pca_add_bus(&pca_isa_ops) < 0) {
  		dev_err(dev, "Failed to add i2c bus
  ");
  		goto out_irq;
  	}
  
  	return 0;
  
   out_irq:
  	if (irq > -1)
  		free_irq(irq, &pca_isa_ops);
   out_region:
  	release_region(base, IO_SIZE);
   out:
  	return -ENODEV;
  }
  
  static int pca_isa_remove(struct device *dev, unsigned int id)
  {
  	i2c_del_adapter(&pca_isa_ops);
  
  	if (irq > -1) {
  		disable_irq(irq);
  		free_irq(irq, &pca_isa_ops);
  	}
  	release_region(base, IO_SIZE);
  
  	return 0;
  }
  
  static struct isa_driver pca_isa_driver = {
  	.match		= pca_isa_match,
  	.probe		= pca_isa_probe,
  	.remove		= pca_isa_remove,
  	.driver = {
  		.owner	= THIS_MODULE,
  		.name	= DRIVER,
  	}
  };
  
  static int __init pca_isa_init(void)
  {
  	return isa_register_driver(&pca_isa_driver, 1);
  }
  
  static void __exit pca_isa_exit(void)
  {
  	isa_unregister_driver(&pca_isa_driver);
  }
  
  MODULE_AUTHOR("Ian Campbell <icampbell@arcom.com>");
  MODULE_DESCRIPTION("ISA base PCA9564/PCA9665 driver");
  MODULE_LICENSE("GPL");
  
  module_param(base, ulong, 0);
  MODULE_PARM_DESC(base, "I/O base address");
  
  module_param(irq, int, 0);
  MODULE_PARM_DESC(irq, "IRQ");
  module_param(clock, int, 0);
  MODULE_PARM_DESC(clock, "Clock rate in hertz.
  \t\t"
  		"For PCA9564: 330000,288000,217000,146000,"
  		"88000,59000,44000,36000
  "
  		"\t\tFor PCA9665:\tStandard: 60300 - 100099
  "
  		"\t\t\t\tFast: 100100 - 400099
  "
  		"\t\t\t\tFast+: 400100 - 10000099
  "
  		"\t\t\t\tTurbo: Up to 1265800");
  
  module_init(pca_isa_init);
  module_exit(pca_isa_exit);