drivers/i2c/busses/i2c-at91.c - kernel/windcharger - Git at Google

 /*
     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/kernel.h>
 #include <linux/err.h>
 #include <linux/slab.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 <linux/io.h>

 #include <mach/at91_twi.h>
 #include <mach/board.h>
 #include <mach/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 separate
  * 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, resource_size(res), "at91_i2c"))
 		return -EBUSY;

 	twi_base = ioremap(res->start, resource_size(res));
 	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;
 	}
 	snprintf(adapter->name, sizeof(adapter->name), "AT91");
 	adapter->algo = &at91_algorithm;
 	adapter->class = I2C_CLASS_HWMON;
 	adapter->dev.parent = &pdev->dev;
 	/* adapter->id == 0 ... only one TWI controller for now */

 	platform_set_drvdata(pdev, adapter);

 	clk_enable(twi_clk);		/* enable peripheral clock */
 	at91_twi_hwinit();		/* initialize TWI controller */

 	rc = i2c_add_numbered_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, resource_size(res));

 	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, resource_size(res));

 	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,
 	},
 };

 module_platform_driver(at91_i2c_driver);

 MODULE_AUTHOR("Rick Bronson");
 MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
 MODULE_LICENSE("GPL");
 MODULE_ALIAS("platform:at91_i2c");
	/*
	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/kernel.h>
	#include <linux/err.h>
	#include <linux/slab.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 <linux/io.h>

	#include <mach/at91_twi.h>
	#include <mach/board.h>
	#include <mach/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 separate
	* 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, resource_size(res), "at91_i2c"))
	return -EBUSY;

	twi_base = ioremap(res->start, resource_size(res));
	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;
	}
	snprintf(adapter->name, sizeof(adapter->name), "AT91");
	adapter->algo = &at91_algorithm;
	adapter->class = I2C_CLASS_HWMON;
	adapter->dev.parent = &pdev->dev;
	/* adapter->id == 0 ... only one TWI controller for now */

	platform_set_drvdata(pdev, adapter);

	clk_enable(twi_clk); /* enable peripheral clock */
	at91_twi_hwinit(); /* initialize TWI controller */

	rc = i2c_add_numbered_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, resource_size(res));

	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, resource_size(res));

	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,
	},
	};

	module_platform_driver(at91_i2c_driver);

	MODULE_AUTHOR("Rick Bronson");
	MODULE_DESCRIPTION("I2C (TWI) driver for Atmel AT91");
	MODULE_LICENSE("GPL");
	MODULE_ALIAS("platform:at91_i2c");