/*
 * (C) Copyright 2003-2004
 * Humboldt Solutions Ltd, adrian@humboldt.co.uk.

 * This is a combined i2c adapter and algorithm driver for the
 * MPC107/Tsi107 PowerPC northbridge and processors that include
 * the same I2C unit (8240, 8245, 85xx).
 *
 * Release 0.8
 *
 * This file is licensed under the terms of the GNU General Public
 * License version 2. This program is licensed "as is" without any
 * warranty of any kind, whether express or implied.
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/sched.h>
#include <linux/init.h>
#include <linux/of_platform.h>
#include <linux/of_i2c.h>

#include <asm/io.h>
#include <linux/fsl_devices.h>
#include <linux/i2c.h>
#include <linux/interrupt.h>
#include <linux/delay.h>

#define DRV_NAME "mpc-i2c"

#define MPC_I2C_FDR 	0x04
#define MPC_I2C_CR	0x08
#define MPC_I2C_SR	0x0c
#define MPC_I2C_DR	0x10
#define MPC_I2C_DFSRR 0x14

#define CCR_MEN  0x80
#define CCR_MIEN 0x40
#define CCR_MSTA 0x20
#define CCR_MTX  0x10
#define CCR_TXAK 0x08
#define CCR_RSTA 0x04

#define CSR_MCF  0x80
#define CSR_MAAS 0x40
#define CSR_MBB  0x20
#define CSR_MAL  0x10
#define CSR_SRW  0x04
#define CSR_MIF  0x02
#define CSR_RXAK 0x01

struct mpc_i2c {
	void __iomem *base;
	u32 interrupt;
	wait_queue_head_t queue;
	struct i2c_adapter adap;
	int irq;
	u32 flags;
};

static __inline__ void writeccr(struct mpc_i2c *i2c, u32 x)
{
	writeb(x, i2c->base + MPC_I2C_CR);
}

static irqreturn_t mpc_i2c_isr(int irq, void *dev_id)
{
	struct mpc_i2c *i2c = dev_id;
	if (readb(i2c->base + MPC_I2C_SR) & CSR_MIF) {
		/* Read again to allow register to stabilise */
		i2c->interrupt = readb(i2c->base + MPC_I2C_SR);
		writeb(0, i2c->base + MPC_I2C_SR);
		wake_up_interruptible(&i2c->queue);
	}
	return IRQ_HANDLED;
}

/* Sometimes 9th clock pulse isn't generated, and slave doesn't release
 * the bus, because it wants to send ACK.
 * Following sequence of enabling/disabling and sending start/stop generates
 * the pulse, so it's all OK.
 */
static void mpc_i2c_fixup(struct mpc_i2c *i2c)
{
	writeccr(i2c, 0);
	udelay(30);
	writeccr(i2c, CCR_MEN);
	udelay(30);
	writeccr(i2c, CCR_MSTA | CCR_MTX);
	udelay(30);
	writeccr(i2c, CCR_MSTA | CCR_MTX | CCR_MEN);
	udelay(30);
	writeccr(i2c, CCR_MEN);
	udelay(30);
}

static int i2c_wait(struct mpc_i2c *i2c, unsigned timeout, int writing)
{
	unsigned long orig_jiffies = jiffies;
	u32 x;
	int result = 0;

	if (i2c->irq == NO_IRQ)
	{
		while (!(readb(i2c->base + MPC_I2C_SR) & CSR_MIF)) {
			schedule();
			if (time_after(jiffies, orig_jiffies + timeout)) {
				pr_debug("I2C: timeout\n");
				writeccr(i2c, 0);
				result = -EIO;
				break;
			}
		}
		x = readb(i2c->base + MPC_I2C_SR);
		writeb(0, i2c->base + MPC_I2C_SR);
	} else {
		/* Interrupt mode */
		result = wait_event_interruptible_timeout(i2c->queue,
			(i2c->interrupt & CSR_MIF), timeout * HZ);

		if (unlikely(result < 0)) {
			pr_debug("I2C: wait interrupted\n");
			writeccr(i2c, 0);
		} else if (unlikely(!(i2c->interrupt & CSR_MIF))) {
			pr_debug("I2C: wait timeout\n");
			writeccr(i2c, 0);
			result = -ETIMEDOUT;
		}

		x = i2c->interrupt;
		i2c->interrupt = 0;
	}

	if (result < 0)
		return result;

	if (!(x & CSR_MCF)) {
		pr_debug("I2C: unfinished\n");
		return -EIO;
	}

	if (x & CSR_MAL) {
		pr_debug("I2C: MAL\n");
		return -EIO;
	}

	if (writing && (x & CSR_RXAK)) {
		pr_debug("I2C: No RXAK\n");
		/* generate stop */
		writeccr(i2c, CCR_MEN);
		return -EIO;
	}
	return 0;
}

static void mpc_i2c_setclock(struct mpc_i2c *i2c)
{
	/* Set clock and filters */
	if (i2c->flags & FSL_I2C_DEV_SEPARATE_DFSRR) {
		writeb(0x31, i2c->base + MPC_I2C_FDR);
		writeb(0x10, i2c->base + MPC_I2C_DFSRR);
	} else if (i2c->flags & FSL_I2C_DEV_CLOCK_5200)
		writeb(0x3f, i2c->base + MPC_I2C_FDR);
	else
		writel(0x1031, i2c->base + MPC_I2C_FDR);
}

static void mpc_i2c_start(struct mpc_i2c *i2c)
{
	/* Clear arbitration */
	writeb(0, i2c->base + MPC_I2C_SR);
	/* Start with MEN */
	writeccr(i2c, CCR_MEN);
}

static void mpc_i2c_stop(struct mpc_i2c *i2c)
{
	writeccr(i2c, CCR_MEN);
}

static int mpc_write(struct mpc_i2c *i2c, int target,
		     const u8 * data, int length, int restart)
{
	int i, result;
	unsigned timeout = i2c->adap.timeout;
	u32 flags = restart ? CCR_RSTA : 0;

	/* Start with MEN */
	if (!restart)
		writeccr(i2c, CCR_MEN);
	/* Start as master */
	writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA | CCR_MTX | flags);
	/* Write target byte */
	writeb((target << 1), i2c->base + MPC_I2C_DR);

	result = i2c_wait(i2c, timeout, 1);
	if (result < 0)
		return result;

	for (i = 0; i < length; i++) {
		/* Write data byte */
		writeb(data[i], i2c->base + MPC_I2C_DR);

		result = i2c_wait(i2c, timeout, 1);
		if (result < 0)
			return result;
	}

	return 0;
}

static int mpc_read(struct mpc_i2c *i2c, int target,
		    u8 * data, int length, int restart)
{
	unsigned timeout = i2c->adap.timeout;
	int i, result;
	u32 flags = restart ? CCR_RSTA : 0;

	/* Start with MEN */
	if (!restart)
		writeccr(i2c, CCR_MEN);
	/* Switch to read - restart */
	writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA | CCR_MTX | flags);
	/* Write target address byte - this time with the read flag set */
	writeb((target << 1) | 1, i2c->base + MPC_I2C_DR);

	result = i2c_wait(i2c, timeout, 1);
	if (result < 0)
		return result;

	if (length) {
		if (length == 1)
			writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA | CCR_TXAK);
		else
			writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA);
		/* Dummy read */
		readb(i2c->base + MPC_I2C_DR);
	}

	for (i = 0; i < length; i++) {
		result = i2c_wait(i2c, timeout, 0);
		if (result < 0)
			return result;

		/* Generate txack on next to last byte */
		if (i == length - 2)
			writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_MSTA | CCR_TXAK);
		/* Generate stop on last byte */
		if (i == length - 1)
			writeccr(i2c, CCR_MIEN | CCR_MEN | CCR_TXAK);
		data[i] = readb(i2c->base + MPC_I2C_DR);
	}

	return length;
}

static int mpc_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
{
	struct i2c_msg *pmsg;
	int i;
	int ret = 0;
	unsigned long orig_jiffies = jiffies;
	struct mpc_i2c *i2c = i2c_get_adapdata(adap);

	mpc_i2c_start(i2c);

	/* Allow bus up to 1s to become not busy */
	while (readb(i2c->base + MPC_I2C_SR) & CSR_MBB) {
		if (signal_pending(current)) {
			pr_debug("I2C: Interrupted\n");
			writeccr(i2c, 0);
			return -EINTR;
		}
		if (time_after(jiffies, orig_jiffies + HZ)) {
			pr_debug("I2C: timeout\n");
			if (readb(i2c->base + MPC_I2C_SR) ==
			    (CSR_MCF | CSR_MBB | CSR_RXAK))
				mpc_i2c_fixup(i2c);
			return -EIO;
		}
		schedule();
	}

	for (i = 0; ret >= 0 && i < num; i++) {
		pmsg = &msgs[i];
		pr_debug("Doing %s %d bytes to 0x%02x - %d of %d messages\n",
			 pmsg->flags & I2C_M_RD ? "read" : "write",
			 pmsg->len, pmsg->addr, i + 1, num);
		if (pmsg->flags & I2C_M_RD)
			ret =
			    mpc_read(i2c, pmsg->addr, pmsg->buf, pmsg->len, i);
		else
			ret =
			    mpc_write(i2c, pmsg->addr, pmsg->buf, pmsg->len, i);
	}
	mpc_i2c_stop(i2c);
	return (ret < 0) ? ret : num;
}

static u32 mpc_functionality(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;
}

static const struct i2c_algorithm mpc_algo = {
	.master_xfer = mpc_xfer,
	.functionality = mpc_functionality,
};

static struct i2c_adapter mpc_ops = {
	.owner = THIS_MODULE,
	.name = "MPC adapter",
	.id = I2C_HW_MPC107,
	.algo = &mpc_algo,
	.class = I2C_CLASS_HWMON,
	.timeout = 1,
};

static int __devinit fsl_i2c_probe(struct of_device *op, const struct of_device_id *match)
{
	int result = 0;
	struct mpc_i2c *i2c;

	i2c = kzalloc(sizeof(*i2c), GFP_KERNEL);
	if (!i2c)
		return -ENOMEM;

	if (of_get_property(op->node, "dfsrr", NULL))
		i2c->flags |= FSL_I2C_DEV_SEPARATE_DFSRR;

	if (of_device_is_compatible(op->node, "fsl,mpc5200-i2c") ||
			of_device_is_compatible(op->node, "mpc5200-i2c"))
		i2c->flags |= FSL_I2C_DEV_CLOCK_5200;

	init_waitqueue_head(&i2c->queue);

	i2c->base = of_iomap(op->node, 0);
	if (!i2c->base) {
		printk(KERN_ERR "i2c-mpc - failed to map controller\n");
		result = -ENOMEM;
		goto fail_map;
	}

	i2c->irq = irq_of_parse_and_map(op->node, 0);
	if (i2c->irq != NO_IRQ) { /* i2c->irq = NO_IRQ implies polling */
		result = request_irq(i2c->irq, mpc_i2c_isr,
				     IRQF_SHARED, "i2c-mpc", i2c);
		if (result < 0) {
			printk(KERN_ERR "i2c-mpc - failed to attach interrupt\n");
			goto fail_request;
		}
	}
	
	mpc_i2c_setclock(i2c);

	dev_set_drvdata(&op->dev, i2c);

	i2c->adap = mpc_ops;
	i2c_set_adapdata(&i2c->adap, i2c);
	i2c->adap.dev.parent = &op->dev;

	result = i2c_add_adapter(&i2c->adap);
	if (result < 0) {
		printk(KERN_ERR "i2c-mpc - failed to add adapter\n");
		goto fail_add;
	}
	of_register_i2c_devices(&i2c->adap, op->node);

	return result;

 fail_add:
	dev_set_drvdata(&op->dev, NULL);
	free_irq(i2c->irq, i2c);
 fail_request:
	irq_dispose_mapping(i2c->irq);
 	iounmap(i2c->base);
 fail_map:
	kfree(i2c);
	return result;
};

static int __devexit fsl_i2c_remove(struct of_device *op)
{
	struct mpc_i2c *i2c = dev_get_drvdata(&op->dev);

	i2c_del_adapter(&i2c->adap);
	dev_set_drvdata(&op->dev, NULL);

	if (i2c->irq != NO_IRQ)
		free_irq(i2c->irq, i2c);

	irq_dispose_mapping(i2c->irq);
	iounmap(i2c->base);
	kfree(i2c);
	return 0;
};

static const struct of_device_id mpc_i2c_of_match[] = {
	{.compatible = "fsl-i2c",},
	{},
};
MODULE_DEVICE_TABLE(of, mpc_i2c_of_match);


/* Structure for a device driver */
static struct of_platform_driver mpc_i2c_driver = {
	.match_table	= mpc_i2c_of_match,
	.probe		= fsl_i2c_probe,
	.remove		= __devexit_p(fsl_i2c_remove),
	.driver		= {
		.owner	= THIS_MODULE,
		.name	= DRV_NAME,
	},
};

static int __init fsl_i2c_init(void)
{
	int rv;

	rv = of_register_platform_driver(&mpc_i2c_driver);
	if (rv)
		printk(KERN_ERR DRV_NAME 
		       " of_register_platform_driver failed (%i)\n", rv);
	return rv;
}

static void __exit fsl_i2c_exit(void)
{
	of_unregister_platform_driver(&mpc_i2c_driver);
}

module_init(fsl_i2c_init);
module_exit(fsl_i2c_exit);

MODULE_AUTHOR("Adrian Cox <adrian@humboldt.co.uk>");
MODULE_DESCRIPTION
    ("I2C-Bus adapter for MPC107 bridge and MPC824x/85xx/52xx processors");
MODULE_LICENSE("GPL");