/*
 *  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/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 <asm/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  = I2C_PCA_CON_59kHz;

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("*** write %s at %#lx <= %#04x\n", 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("*** read  %s => %#04x\n", names[reg], res);
	}
#endif
	return res;
}

static int pca_isa_waitforcompletion(void *pd)
{
	int ret = 0;

	if (irq > -1) {
		ret = wait_event_interruptible(pca_wait,
					       pca_isa_readbyte(pd, I2C_PCA_CON) & I2C_PCA_CON_SI);
	} else {
		while ((pca_isa_readbyte(pd, I2C_PCA_CON) & I2C_PCA_CON_SI) == 0)
			udelay(100);
	}
	return ret;
}

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\n");
}

static irqreturn_t pca_handler(int this_irq, void *dev_id) {
	wake_up_interruptible(&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 ISA Adapter",
	.timeout	= 100,
};

static int __devinit 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)\n");
	} else
		dev_err(dev, "Please specify I/O base\n");

	return match;
}

static int __devinit pca_isa_probe(struct device *dev, unsigned int id)
{
	init_waitqueue_head(&pca_wait);

	dev_info(dev, "i/o base %#08lx. irq %d\n", base, irq);

#ifdef CONFIG_PPC
	if (check_legacy_ioport(base)) {
		dev_err(dev, "I/O address %#08lx is not available\n", base);
		goto out;
	}
#endif

	if (!request_region(base, IO_SIZE, "i2c-pca-isa")) {
		dev_err(dev, "I/O address %#08lx is in use\n", 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\n", 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\n");
		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 __devexit 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		= __devexit_p(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 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 as described in table 1 of PCA9564 datasheet");

module_init(pca_isa_init);
module_exit(pca_isa_exit);