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Commit e0b9b7b0 authored by Kevin Strasser's avatar Kevin Strasser Committed by Wolfram Sang
Browse files

i2c: Kontron PLD i2c bus driver 



Add i2c support for the on-board PLD found on some Kontron embedded
modules.

Originally-From: Michael Brunner <michael.brunner@kontron.com>
Signed-off-by: default avatarKevin Strasser <kevin.strasser@linux.intel.com>
Acked-by: default avatarGuenter Roeck <linux@roeck-us.net>
Acked-by: default avatarDarren Hart <dvhart@linux.intel.com>
Signed-off-by: default avatarWolfram Sang <wsa@the-dreams.de>
parent 88a8e4aa

drivers/i2c/busses/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -485,6 +485,16 @@ config I2C_IOP3XX 
	  This driver can also be built as a module.  If so, the module

	  will be called i2c-iop3xx.



config I2C_KEMPLD

	tristate "Kontron COM I2C Controller"

	depends on MFD_KEMPLD

	help

	  This enables support for the I2C bus interface on some Kontron ETX

	  and COMexpress (ETXexpress) modules.



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

	  will be called i2c-kempld.



config I2C_MPC

	tristate "MPC107/824x/85xx/512x/52xx/83xx/86xx"

	depends on PPC

drivers/i2c/busses/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -47,6 +47,7 @@ obj-$(CONFIG_I2C_HIGHLANDER) += i2c-highlander.o 
obj-$(CONFIG_I2C_IBM_IIC)	+= i2c-ibm_iic.o

obj-$(CONFIG_I2C_IMX)		+= i2c-imx.o

obj-$(CONFIG_I2C_IOP3XX)	+= i2c-iop3xx.o

obj-$(CONFIG_I2C_KEMPLD)	+= i2c-kempld.o

obj-$(CONFIG_I2C_MPC)		+= i2c-mpc.o

obj-$(CONFIG_I2C_MV64XXX)	+= i2c-mv64xxx.o

obj-$(CONFIG_I2C_MXS)		+= i2c-mxs.o

drivers/i2c/busses/i2c-kempld.c

0 → 100644
+410 −0
Original line number Diff line number Diff line 
/*

 * I2C bus driver for Kontron COM modules

 *

 * Copyright (c) 2010-2013 Kontron Europe GmbH

 * Author: Michael Brunner <michael.brunner@kontron.com>

 *

 * The driver is based on the i2c-ocores driver by Peter Korsgaard.

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License 2 as published

 * by the Free Software Foundation.

 *

 * 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.

 */



#include <linux/module.h>

#include <linux/platform_device.h>

#include <linux/i2c.h>

#include <linux/delay.h>

#include <linux/mfd/kempld.h>



#define KEMPLD_I2C_PRELOW	0x0b

#define KEMPLD_I2C_PREHIGH	0x0c

#define KEMPLD_I2C_DATA		0x0e



#define KEMPLD_I2C_CTRL		0x0d

#define I2C_CTRL_IEN		0x40

#define I2C_CTRL_EN		0x80



#define KEMPLD_I2C_STAT		0x0f

#define I2C_STAT_IF		0x01

#define I2C_STAT_TIP		0x02

#define I2C_STAT_ARBLOST	0x20

#define I2C_STAT_BUSY		0x40

#define I2C_STAT_NACK		0x80



#define KEMPLD_I2C_CMD		0x0f

#define I2C_CMD_START		0x91

#define I2C_CMD_STOP		0x41

#define I2C_CMD_READ		0x21

#define I2C_CMD_WRITE		0x11

#define I2C_CMD_READ_ACK	0x21

#define I2C_CMD_READ_NACK	0x29

#define I2C_CMD_IACK		0x01



#define KEMPLD_I2C_FREQ_MAX	2700	/* 2.7 mHz */

#define KEMPLD_I2C_FREQ_STD	100	/* 100 kHz */



enum {

	STATE_DONE = 0,

	STATE_INIT,

	STATE_ADDR,

	STATE_ADDR10,

	STATE_START,

	STATE_WRITE,

	STATE_READ,

	STATE_ERROR,

};



struct kempld_i2c_data {

	struct device			*dev;

	struct kempld_device_data	*pld;

	struct i2c_adapter		adap;

	struct i2c_msg			*msg;

	int				pos;

	int				nmsgs;

	int				state;

	bool				was_active;

};



static unsigned int bus_frequency = KEMPLD_I2C_FREQ_STD;

module_param(bus_frequency, uint, 0);

MODULE_PARM_DESC(bus_frequency, "Set I2C bus frequency in kHz (default="

				__MODULE_STRING(KEMPLD_I2C_FREQ_STD)")");



static int i2c_bus = -1;

module_param(i2c_bus, int, 0);

MODULE_PARM_DESC(i2c_bus, "Set I2C bus number (default=-1 for dynamic assignment)");



static bool i2c_gpio_mux;

module_param(i2c_gpio_mux, bool, 0);

MODULE_PARM_DESC(i2c_gpio_mux, "Enable I2C port on GPIO out (default=false)");



/*

 * kempld_get_mutex must be called prior to calling this function.

 */

static int kempld_i2c_process(struct kempld_i2c_data *i2c)

{

	struct kempld_device_data *pld = i2c->pld;

	u8 stat = kempld_read8(pld, KEMPLD_I2C_STAT);

	struct i2c_msg *msg = i2c->msg;

	u8 addr;



	/* Ready? */

	if (stat & I2C_STAT_TIP)

		return -EBUSY;



	if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR) {

		/* Stop has been sent */

		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);

		if (i2c->state == STATE_ERROR)

			return -EIO;

		return 0;

	}



	/* Error? */

	if (stat & I2C_STAT_ARBLOST) {

		i2c->state = STATE_ERROR;

		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);

		return -EAGAIN;

	}



	if (i2c->state == STATE_INIT) {

		if (stat & I2C_STAT_BUSY)

			return -EBUSY;



		i2c->state = STATE_ADDR;

	}



	if (i2c->state == STATE_ADDR) {

		/* 10 bit address? */

		if (i2c->msg->flags & I2C_M_TEN) {

			addr = 0xf0 | ((i2c->msg->addr >> 7) & 0x6);

			i2c->state = STATE_ADDR10;

		} else {

			addr = (i2c->msg->addr << 1);

			i2c->state = STATE_START;

		}



		/* Set read bit if necessary */

		addr |= (i2c->msg->flags & I2C_M_RD) ? 1 : 0;



		kempld_write8(pld, KEMPLD_I2C_DATA, addr);

		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_START);



		return 0;

	}



	/* Second part of 10 bit addressing */

	if (i2c->state == STATE_ADDR10) {

		kempld_write8(pld, KEMPLD_I2C_DATA, i2c->msg->addr & 0xff);

		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);



		i2c->state = STATE_START;

		return 0;

	}



	if (i2c->state == STATE_START || i2c->state == STATE_WRITE) {

		i2c->state = (msg->flags & I2C_M_RD) ? STATE_READ : STATE_WRITE;



		if (stat & I2C_STAT_NACK) {

			i2c->state = STATE_ERROR;

			kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);

			return -ENXIO;

		}

	} else {

		msg->buf[i2c->pos++] = kempld_read8(pld, KEMPLD_I2C_DATA);

	}



	if (i2c->pos >= msg->len) {

		i2c->nmsgs--;

		i2c->msg++;

		i2c->pos = 0;

		msg = i2c->msg;



		if (i2c->nmsgs) {

			if (!(msg->flags & I2C_M_NOSTART)) {

				i2c->state = STATE_ADDR;

				return 0;

			} else {

				i2c->state = (msg->flags & I2C_M_RD)

					? STATE_READ : STATE_WRITE;

			}

		} else {

			i2c->state = STATE_DONE;

			kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);

			return 0;

		}

	}



	if (i2c->state == STATE_READ) {

		kempld_write8(pld, KEMPLD_I2C_CMD, i2c->pos == (msg->len - 1) ?

			      I2C_CMD_READ_NACK : I2C_CMD_READ_ACK);

	} else {

		kempld_write8(pld, KEMPLD_I2C_DATA, msg->buf[i2c->pos++]);

		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_WRITE);

	}



	return 0;

}



static int kempld_i2c_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs,

				int num)

{

	struct kempld_i2c_data *i2c = i2c_get_adapdata(adap);

	struct kempld_device_data *pld = i2c->pld;

	unsigned long timeout = jiffies + HZ;

	int ret;



	i2c->msg = msgs;

	i2c->pos = 0;

	i2c->nmsgs = num;

	i2c->state = STATE_INIT;



	/* Handle the transfer */

	while (time_before(jiffies, timeout)) {

		kempld_get_mutex(pld);

		ret = kempld_i2c_process(i2c);

		kempld_release_mutex(pld);



		if (i2c->state == STATE_DONE || i2c->state == STATE_ERROR)

			return (i2c->state == STATE_DONE) ? num : ret;



		if (ret == 0)

			timeout = jiffies + HZ;



		usleep_range(5, 15);

	}



	i2c->state = STATE_ERROR;



	return -ETIMEDOUT;

}



/*

 * kempld_get_mutex must be called prior to calling this function.

 */

static void kempld_i2c_device_init(struct kempld_i2c_data *i2c)

{

	struct kempld_device_data *pld = i2c->pld;

	u16 prescale_corr;

	long prescale;

	u8 ctrl;

	u8 stat;

	u8 cfg;



	/* Make sure the device is disabled */

	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);

	ctrl &= ~(I2C_CTRL_EN | I2C_CTRL_IEN);

	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);



	if (bus_frequency > KEMPLD_I2C_FREQ_MAX)

		bus_frequency = KEMPLD_I2C_FREQ_MAX;



	if (pld->info.spec_major == 1)

		prescale = pld->pld_clock / bus_frequency * 5 - 1000;

	else

		prescale = pld->pld_clock / bus_frequency * 4 - 3000;



	if (prescale < 0)

		prescale = 0;



	/* Round to the best matching value */

	prescale_corr = prescale / 1000;

	if (prescale % 1000 >= 500)

		prescale_corr++;



	kempld_write8(pld, KEMPLD_I2C_PRELOW, prescale_corr & 0xff);

	kempld_write8(pld, KEMPLD_I2C_PREHIGH, prescale_corr >> 8);



	/* Activate I2C bus output on GPIO pins */

	cfg = kempld_read8(pld, KEMPLD_CFG);

	if (i2c_gpio_mux)

		cfg |= KEMPLD_CFG_GPIO_I2C_MUX;

	else

		cfg &= ~KEMPLD_CFG_GPIO_I2C_MUX;

	kempld_write8(pld, KEMPLD_CFG, cfg);



	/* Enable the device */

	kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_IACK);

	ctrl |= I2C_CTRL_EN;

	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);



	stat = kempld_read8(pld, KEMPLD_I2C_STAT);

	if (stat & I2C_STAT_BUSY)

		kempld_write8(pld, KEMPLD_I2C_CMD, I2C_CMD_STOP);

}



static u32 kempld_i2c_func(struct i2c_adapter *adap)

{

	return I2C_FUNC_I2C | I2C_FUNC_10BIT_ADDR | I2C_FUNC_SMBUS_EMUL;

}



static const struct i2c_algorithm kempld_i2c_algorithm = {

	.master_xfer	= kempld_i2c_xfer,

	.functionality	= kempld_i2c_func,

};



static struct i2c_adapter kempld_i2c_adapter = {

	.owner		= THIS_MODULE,

	.name		= "i2c-kempld",

	.class		= I2C_CLASS_HWMON | I2C_CLASS_SPD,

	.algo		= &kempld_i2c_algorithm,

};



static int kempld_i2c_probe(struct platform_device *pdev)

{

	struct kempld_device_data *pld = dev_get_drvdata(pdev->dev.parent);

	struct kempld_i2c_data *i2c;

	int ret;

	u8 ctrl;



	i2c = devm_kzalloc(&pdev->dev, sizeof(*i2c), GFP_KERNEL);

	if (!i2c)

		return -ENOMEM;



	i2c->pld = pld;

	i2c->dev = &pdev->dev;

	i2c->adap = kempld_i2c_adapter;

	i2c->adap.dev.parent = i2c->dev;

	i2c_set_adapdata(&i2c->adap, i2c);

	platform_set_drvdata(pdev, i2c);



	kempld_get_mutex(pld);

	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);



	if (ctrl & I2C_CTRL_EN)

		i2c->was_active = true;



	kempld_i2c_device_init(i2c);

	kempld_release_mutex(pld);



	/* Add I2C adapter to I2C tree */

	if (i2c_bus >= -1)

		i2c->adap.nr = i2c_bus;

	ret = i2c_add_numbered_adapter(&i2c->adap);

	if (ret)

		return ret;



	dev_info(i2c->dev, "I2C bus initialized at %dkHz\n",

		 bus_frequency);



	return 0;

}



static int kempld_i2c_remove(struct platform_device *pdev)

{

	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);

	struct kempld_device_data *pld = i2c->pld;

	u8 ctrl;



	kempld_get_mutex(pld);

	/*

	 * Disable I2C logic if it was not activated before the

	 * driver loaded

	 */

	if (!i2c->was_active) {

		ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);

		ctrl &= ~I2C_CTRL_EN;

		kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);

	}

	kempld_release_mutex(pld);



	i2c_del_adapter(&i2c->adap);



	return 0;

}



#ifdef CONFIG_PM

static int kempld_i2c_suspend(struct platform_device *pdev, pm_message_t state)

{

	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);

	struct kempld_device_data *pld = i2c->pld;

	u8 ctrl;



	kempld_get_mutex(pld);

	ctrl = kempld_read8(pld, KEMPLD_I2C_CTRL);

	ctrl &= ~I2C_CTRL_EN;

	kempld_write8(pld, KEMPLD_I2C_CTRL, ctrl);

	kempld_release_mutex(pld);



	return 0;

}



static int kempld_i2c_resume(struct platform_device *pdev)

{

	struct kempld_i2c_data *i2c = platform_get_drvdata(pdev);

	struct kempld_device_data *pld = i2c->pld;



	kempld_get_mutex(pld);

	kempld_i2c_device_init(i2c);

	kempld_release_mutex(pld);



	return 0;

}

#else

#define kempld_i2c_suspend	NULL

#define kempld_i2c_resume	NULL

#endif



static struct platform_driver kempld_i2c_driver = {

	.driver = {

		.name = "kempld-i2c",

		.owner = THIS_MODULE,

	},

	.probe		= kempld_i2c_probe,

	.remove		= kempld_i2c_remove,

	.suspend	= kempld_i2c_suspend,

	.resume		= kempld_i2c_resume,

};



module_platform_driver(kempld_i2c_driver);



MODULE_DESCRIPTION("KEM PLD I2C Driver");

MODULE_AUTHOR("Michael Brunner <michael.brunner@kontron.com>");

MODULE_LICENSE("GPL");

MODULE_ALIAS("platform:kempld_i2c");