i2c: New Atmel AT91 bus driver

	  This driver can also be built as a module.  If so, the module

	  will be called i2c-amd8111.

config I2C_AT91

	tristate "Atmel AT91 I2C Two-Wire interface (TWI)"

	depends on I2C && ARCH_AT91 && EXPERIMENTAL

	help

	  This supports the use of the I2C interface on Atmel AT91

	  processors.

config I2C_AU1550

	tristate "Au1550/Au1200 SMBus interface"

	depends on I2C && (SOC_AU1550 || SOC_AU1200)

obj-$(CONFIG_I2C_AMD756)	+= i2c-amd756.o

obj-$(CONFIG_I2C_AMD756_S4882)	+= i2c-amd756-s4882.o

obj-$(CONFIG_I2C_AMD8111)	+= i2c-amd8111.o

obj-$(CONFIG_I2C_AT91)		+= i2c-at91.o

obj-$(CONFIG_I2C_AU1550)	+= i2c-au1550.o

obj-$(CONFIG_I2C_ELEKTOR)	+= i2c-elektor.o

obj-$(CONFIG_I2C_HYDRA)		+= i2c-hydra.o

/*

    i2c Support for Atmel's AT91 Two-Wire Interface (TWI)

    Copyright (C) 2004 Rick Bronson

    Converted to 2.6 by Andrew Victor <andrew@sanpeople.com>

    Borrowed heavily from original work by:

    Copyright (C) 2000 Philip Edelbrock <phil@stimpy.netroedge.com>

    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.

*/

#include <linux/module.h>

#include <linux/version.h>

#include <linux/kernel.h>

#include <linux/slab.h>

#include <linux/pci.h>

#include <linux/types.h>

#include <linux/delay.h>

#include <linux/i2c.h>

#include <linux/init.h>

#include <linux/clk.h>

#include <linux/platform_device.h>

#include <asm/io.h>

#include <asm/arch/at91_twi.h>

#include <asm/arch/board.h>

#include <asm/arch/cpu.h>

#define TWI_CLOCK		100000		/* Hz. max 400 Kbits/sec */

static struct clk *twi_clk;

static void __iomem *twi_base;

#define at91_twi_read(reg)		__raw_readl(twi_base + (reg))

#define at91_twi_write(reg, val)	__raw_writel((val), twi_base + (reg))

/*

 * Initialize the TWI hardware registers.

 */

static void __devinit at91_twi_hwinit(void)

{

	unsigned long cdiv, ckdiv;

	at91_twi_write(AT91_TWI_IDR, 0xffffffff);	/* Disable all interrupts */

	at91_twi_write(AT91_TWI_CR, AT91_TWI_SWRST);	/* Reset peripheral */

	at91_twi_write(AT91_TWI_CR, AT91_TWI_MSEN);	/* Set Master mode */

	/* Calcuate clock dividers */

	cdiv = (clk_get_rate(twi_clk) / (2 * TWI_CLOCK)) - 3;

	cdiv = cdiv + 1;	/* round up */

	ckdiv = 0;

	while (cdiv > 255) {

		ckdiv++;

		cdiv = cdiv >> 1;

	}

	if (cpu_is_at91rm9200()) {			/* AT91RM9200 Errata #22 */

		if (ckdiv > 5) {

			printk(KERN_ERR "AT91 I2C: Invalid TWI_CLOCK value!\n");

			ckdiv = 5;

		}

	}

	at91_twi_write(AT91_TWI_CWGR, (ckdiv << 16) | (cdiv << 8) | cdiv);

}

/*

 * Poll the i2c status register until the specified bit is set.

 * Returns 0 if timed out (100 msec).

 */

static short at91_poll_status(unsigned long bit)

{

	int loop_cntr = 10000;

	do {

		udelay(10);

	} while (!(at91_twi_read(AT91_TWI_SR) & bit) && (--loop_cntr > 0));

	return (loop_cntr > 0);

}

static int xfer_read(struct i2c_adapter *adap, unsigned char *buf, int length)

{

	/* Send Start */

	at91_twi_write(AT91_TWI_CR, AT91_TWI_START);

	/* Read data */

	while (length--) {

		if (!length)	/* need to send Stop before reading last byte */

			at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP);

		if (!at91_poll_status(AT91_TWI_RXRDY)) {

			dev_dbg(&adap->dev, "RXRDY timeout\n");

			return -ETIMEDOUT;

		}

		*buf++ = (at91_twi_read(AT91_TWI_RHR) & 0xff);

	}

	return 0;

}

static int xfer_write(struct i2c_adapter *adap, unsigned char *buf, int length)

{

	/* Load first byte into transmitter */

	at91_twi_write(AT91_TWI_THR, *buf++);

	/* Send Start */

	at91_twi_write(AT91_TWI_CR, AT91_TWI_START);

	do {

		if (!at91_poll_status(AT91_TWI_TXRDY)) {

			dev_dbg(&adap->dev, "TXRDY timeout\n");

			return -ETIMEDOUT;

		}

		length--;	/* byte was transmitted */

		if (length > 0)		/* more data to send? */

			at91_twi_write(AT91_TWI_THR, *buf++);

	} while (length);

	/* Send Stop */

	at91_twi_write(AT91_TWI_CR, AT91_TWI_STOP);

	return 0;

}

/*

 * Generic i2c master transfer entrypoint.

 *

 * Note: We do not use Atmel's feature of storing the "internal device address".

 * Instead the "internal device address" has to be written using a seperate

 * i2c message.

 * http://lists.arm.linux.org.uk/pipermail/linux-arm-kernel/2004-September/024411.html

 */

static int at91_xfer(struct i2c_adapter *adap, struct i2c_msg *pmsg, int num)

{

	int i, ret;

	dev_dbg(&adap->dev, "at91_xfer: processing %d messages:\n", num);

	for (i = 0; i < num; i++) {

		dev_dbg(&adap->dev, " #%d: %sing %d byte%s %s 0x%02x\n", i,

			pmsg->flags & I2C_M_RD ? "read" : "writ",

			pmsg->len, pmsg->len > 1 ? "s" : "",

			pmsg->flags & I2C_M_RD ? "from" : "to",	pmsg->addr);

		at91_twi_write(AT91_TWI_MMR, (pmsg->addr << 16)

			| ((pmsg->flags & I2C_M_RD) ? AT91_TWI_MREAD : 0));

		if (pmsg->len && pmsg->buf) {	/* sanity check */

			if (pmsg->flags & I2C_M_RD)

				ret = xfer_read(adap, pmsg->buf, pmsg->len);

			else

				ret = xfer_write(adap, pmsg->buf, pmsg->len);

			if (ret)

				return ret;

			/* Wait until transfer is finished */

			if (!at91_poll_status(AT91_TWI_TXCOMP)) {

				dev_dbg(&adap->dev, "TXCOMP timeout\n");

				return -ETIMEDOUT;

			}

		}

		dev_dbg(&adap->dev, "transfer complete\n");

		pmsg++;		/* next message */

	}

	return i;

}

/*

 * Return list of supported functionality.

 */

static u32 at91_func(struct i2c_adapter *adapter)

{

	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL;

}

static struct i2c_algorithm at91_algorithm = {

	.master_xfer	= at91_xfer,

	.functionality	= at91_func,

};

/*

 * Main initialization routine.

 */

static int __devinit at91_i2c_probe(struct platform_device *pdev)

{

	struct i2c_adapter *adapter;

	struct resource *res;

	int rc;

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	if (!res)

		return -ENXIO;

	if (!request_mem_region(res->start, res->end - res->start + 1, "at91_i2c"))

		return -EBUSY;

	twi_base = ioremap(res->start, res->end - res->start + 1);

	if (!twi_base) {

		rc = -ENOMEM;

		goto fail0;

	}

	twi_clk = clk_get(NULL, "twi_clk");

	if (IS_ERR(twi_clk)) {

		dev_err(&pdev->dev, "no clock defined\n");

		rc = -ENODEV;

		goto fail1;

	}

	adapter = kzalloc(sizeof(struct i2c_adapter), GFP_KERNEL);

	if (adapter == NULL) {

		dev_err(&pdev->dev, "can't allocate inteface!\n");

		rc = -ENOMEM;

		goto fail2;

	}

	sprintf(adapter->name, "AT91");

	adapter->algo = &at91_algorithm;

	adapter->class = I2C_CLASS_HWMON;

	adapter->dev.parent = &pdev->dev;

	platform_set_drvdata(pdev, adapter);

	clk_enable(twi_clk);		/* enable peripheral clock */

	at91_twi_hwinit();		/* initialize TWI controller */

	rc = i2c_add_adapter(adapter);

	if (rc) {

		dev_err(&pdev->dev, "Adapter %s registration failed\n",

				adapter->name);

		goto fail3;

	}

	dev_info(&pdev->dev, "AT91 i2c bus driver.\n");

	return 0;

fail3:

	platform_set_drvdata(pdev, NULL);

	kfree(adapter);

	clk_disable(twi_clk);

fail2:

	clk_put(twi_clk);

fail1:

	iounmap(twi_base);

fail0:

	release_mem_region(res->start, res->end - res->start + 1);

	return rc;

}

static int __devexit at91_i2c_remove(struct platform_device *pdev)

{

	struct i2c_adapter *adapter = platform_get_drvdata(pdev);

	struct resource *res;

	int rc;

	rc = i2c_del_adapter(adapter);

	platform_set_drvdata(pdev, NULL);

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);

	iounmap(twi_base);

	release_mem_region(res->start, res->end - res->start + 1);

	clk_disable(twi_clk);		/* disable peripheral clock */

	clk_put(twi_clk);

	return rc;

}

#ifdef CONFIG_PM

/* NOTE: could save a few mA by keeping clock off outside of at91_xfer... */

static int at91_i2c_suspend(struct platform_device *pdev, pm_message_t mesg)

{

	clk_disable(twi_clk);

	return 0;

}

static int at91_i2c_resume(struct platform_device *pdev)

{

	return clk_enable(twi_clk);

}

#else

#define at91_i2c_suspend	NULL

#define at91_i2c_resume		NULL

#endif

static struct platform_driver at91_i2c_driver = {

	.probe		= at91_i2c_probe,

	.remove		= __devexit_p(at91_i2c_remove),

	.suspend	= at91_i2c_suspend,

	.resume		= at91_i2c_resume,

	.driver		= {

		.name	= "at91_i2c",

		.owner	= THIS_MODULE,

	},

};

static int __init at91_i2c_init(void)

{

	return platform_driver_register(&at91_i2c_driver);

}

static void __exit at91_i2c_exit(void)

{

	platform_driver_unregister(&at91_i2c_driver);

}

module_init(at91_i2c_init);

module_exit(at91_i2c_exit);

MODULE_AUTHOR("Rick Bronson");

MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");

MODULE_LICENSE("GPL");