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   NOTE! This copyright does *not* cover user programs that use kernel
 services by normal system calls - this is merely considered normal use
 of the kernel, and does *not* fall under the heading of "derived work".
 Also note that the GPL below is copyrighted by the Free Software
 Foundation, but the instance of code that it refers to (the Linux
 kernel) is copyrighted by me and others who actually wrote it.

 Also note that the only valid version of the GPL as far as the kernel
 is concerned is _this_ particular version of the license (ie v2, not
 v2.2 or v3.x or whatever), unless explicitly otherwise stated.

			Linus Torvalds

----------------------------------------

		    GNU GENERAL PUBLIC LICENSE
		       Version 2, June 1991

 Copyright (C) 1989, 1991 Free Software Foundation, Inc.
                       59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 Everyone is permitted to copy and distribute verbatim copies
 of this license document, but changing it is not allowed.

			    Preamble

  The licenses for most software are designed to take away your
freedom to share and change it.  By contrast, the GNU General Public
License is intended to guarantee your freedom to share and change free
software--to make sure the software is free for all its users.  This
General Public License applies to most of the Free Software
Foundation's software and to any other program whose authors commit to
using it.  (Some other Free Software Foundation software is covered by
the GNU Library General Public License instead.)  You can apply it to
your programs, too.

  When we speak of free software, we are referring to freedom, not
price.  Our General Public Licenses are designed to make sure that you
have the freedom to distribute copies of free software (and charge for
this service if you wish), that you receive source code or can get it
if you want it, that you can change the software or use pieces of it
in new free programs; and that you know you can do these things.

  To protect your rights, we need to make restrictions that forbid
anyone to deny you these rights or to ask you to surrender the rights.
These restrictions translate to certain responsibilities for you if you
distribute copies of the software, or if you modify it.

  For example, if you distribute copies of such a program, whether
gratis or for a fee, you must give the recipients all the rights that
you have.  You must make sure that they, too, receive or can get the
source code.  And you must show them these terms so they know their
rights.

  We protect your rights with two steps: (1) copyright the software, and
(2) offer you this license which gives you legal permission to copy,
distribute and/or modify the software.

  Also, for each author's protection and ours, we want to make certain
that everyone understands that there is no warranty for this free
software.  If the software is modified by someone else and passed on, we
want its recipients to know that what they have is not the original, so
that any problems introduced by others will not reflect on the original
authors' reputations.

  Finally, any free program is threatened constantly by software
patents.  We wish to avoid the danger that redistributors of a free
program will individually obtain patent licenses, in effect making the
program proprietary.  To prevent this, we have made it clear that any
patent must be licensed for everyone's free use or not licensed at all.

  The precise terms and conditions for copying, distribution and
modification follow.

		    GNU GENERAL PUBLIC LICENSE
   TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION

  0. This License applies to any program or other work which contains
a notice placed by the copyright holder saying it may be distributed
under the terms of this General Public License.  The "Program", below,
refers to any such program or work, and a "work based on the Program"
means either the Program or any derivative work under copyright law:
that is to say, a work containing the Program or a portion of it,
either verbatim or with modifications and/or translated into another
language.  (Hereinafter, translation is included without limitation in
the term "modification".)  Each licensee is addressed as "you".

Activities other than copying, distribution and modification are not
covered by this License; they are outside its scope.  The act of
running the Program is not restricted, and the output from the Program
is covered only if its contents constitute a work based on the
Program (independent of having been made by running the Program).
Whether that is true depends on what the Program does.

  1. You may copy and distribute verbatim copies of the Program's
source code as you receive it, in any medium, provided that you
conspicuously and appropriately publish on each copy an appropriate
copyright notice and disclaimer of warranty; keep intact all the
notices that refer to this License and to the absence of any warranty;
and give any other recipients of the Program a copy of this License
along with the Program.

You may charge a fee for the physical act of transferring a copy, and
you may at your option offer warranty protection in exchange for a fee.

  2. You may modify your copy or copies of the Program or any portion
of it, thus forming a work based on the Program, and copy and
distribute such modifications or work under the terms of Section 1
above, provided that you also meet all of these conditions:

    a) You must cause the modified files to carry prominent notices
    stating that you changed the files and the date of any change.

    b) You must cause any work that you distribute or publish, that in
    whole or in part contains or is derived from the Program or any
    part thereof, to be licensed as a whole at no charge to all third
    parties under the terms of this License.

    c) If the modified program normally reads commands interactively
    when run, you must cause it, when started running for such
    interactive use in the most ordinary way, to print or display an
    announcement including an appropriate copyright notice and a
    notice that there is no warranty (or else, saying that you provide
    a warranty) and that users may redistribute the program under
    these conditions, and telling the user how to view a copy of this
    License.  (Exception: if the Program itself is interactive but
    does not normally print such an announcement, your work based on
    the Program is not required to print an announcement.)

These requirements apply to the modified work as a whole.  If
identifiable sections of that work are not derived from the Program,
and can be reasonably considered independent and separate works in
themselves, then this License, and its terms, do not apply to those
sections when you distribute them as separate works.  But when you
distribute the same sections as part of a whole which is a work based
on the Program, the distribution of the whole must be on the terms of
this License, whose permissions for other licensees extend to the
entire whole, and thus to each and every part regardless of who wrote it.

Thus, it is not the intent of this section to claim rights or contest
your rights to work written entirely by you; rather, the intent is to
exercise the right to control the distribution of derivative or
collective works based on the Program.

In addition, mere aggregation of another work not based on the Program
with the Program (or with a work based on the Program) on a volume of
a storage or distribution medium does not bring the other work under
the scope of this License.

  3. You may copy and distribute the Program (or a work based on it,
under Section 2) in object code or executable form under the terms of
Sections 1 and 2 above provided that you also do one of the following:

    a) Accompany it with the complete corresponding machine-readable
    source code, which must be distributed under the terms of Sections
    1 and 2 above on a medium customarily used for software interchange; or,

    b) Accompany it with a written offer, valid for at least three
    years, to give any third party, for a charge no more than your
    cost of physically performing source distribution, a complete
    machine-readable copy of the corresponding source code, to be
    distributed under the terms of Sections 1 and 2 above on a medium
    customarily used for software interchange; or,

    c) Accompany it with the information you received as to the offer
    to distribute corresponding source code.  (This alternative is
    allowed only for noncommercial distribution and only if you
    received the program in object code or executable form with such
    an offer, in accord with Subsection b above.)

The source code for a work means the preferred form of the work for
making modifications to it.  For an executable work, complete source
code means all the source code for all modules it contains, plus any
associated interface definition files, plus the scripts used to
control compilation and installation of the executable.  However, as a
special exception, the source code distributed need not include
anything that is normally distributed (in either source or binary
form) with the major components (compiler, kernel, and so on) of the
operating system on which the executable runs, unless that component
itself accompanies the executable.

If distribution of executable or object code is made by offering
access to copy from a designated place, then offering equivalent
access to copy the source code from the same place counts as
distribution of the source code, even though third parties are not
compelled to copy the source along with the object code.

  4. You may not copy, modify, sublicense, or distribute the Program
except as expressly provided under this License.  Any attempt
otherwise to copy, modify, sublicense or distribute the Program is
void, and will automatically terminate your rights under this License.
However, parties who have received copies, or rights, from you under
this License will not have their licenses terminated so long as such
parties remain in full compliance.

  5. You are not required to accept this License, since you have not
signed it.  However, nothing else grants you permission to modify or
distribute the Program or its derivative works.  These actions are
prohibited by law if you do not accept this License.  Therefore, by
modifying or distributing the Program (or any work based on the
Program), you indicate your acceptance of this License to do so, and
all its terms and conditions for copying, distributing or modifying
the Program or works based on it.

  6. Each time you redistribute the Program (or any work based on the
Program), the recipient automatically receives a license from the
original licensor to copy, distribute or modify the Program subject to
these terms and conditions.  You may not impose any further
restrictions on the recipients' exercise of the rights granted herein.
You are not responsible for enforcing compliance by third parties to
this License.

  7. If, as a consequence of a court judgment or allegation of patent
infringement or for any other reason (not limited to patent issues),
conditions are imposed on you (whether by court order, agreement or
otherwise) that contradict the conditions of this License, they do not
excuse you from the conditions of this License.  If you cannot
distribute so as to satisfy simultaneously your obligations under this
License and any other pertinent obligations, then as a consequence you
may not distribute the Program at all.  For example, if a patent
license would not permit royalty-free redistribution of the Program by
all those who receive copies directly or indirectly through you, then
the only way you could satisfy both it and this License would be to
refrain entirely from distribution of the Program.

If any portion of this section is held invalid or unenforceable under
any particular circumstance, the balance of the section is intended to
apply and the section as a whole is intended to apply in other
circumstances.

It is not the purpose of this section to induce you to infringe any
patents or other property right claims or to contest validity of any
such claims; this section has the sole purpose of protecting the
integrity of the free software distribution system, which is
implemented by public license practices.  Many people have made
generous contributions to the wide range of software distributed
through that system in reliance on consistent application of that
system; it is up to the author/donor to decide if he or she is willing
to distribute software through any other system and a licensee cannot
impose that choice.

This section is intended to make thoroughly clear what is believed to
be a consequence of the rest of this License.

  8. If the distribution and/or use of the Program is restricted in
certain countries either by patents or by copyrighted interfaces, the
original copyright holder who places the Program under this License
may add an explicit geographical distribution limitation excluding
those countries, so that distribution is permitted only in or among
countries not thus excluded.  In such case, this License incorporates
the limitation as if written in the body of this License.

  9. The Free Software Foundation may publish revised and/or new versions
of the General Public License from time to time.  Such new versions will
be similar in spirit to the present version, but may differ in detail to
address new problems or concerns.

Each version is given a distinguishing version number.  If the Program
specifies a version number of this License which applies to it and "any
later version", you have the option of following the terms and conditions
either of that version or of any later version published by the Free
Software Foundation.  If the Program does not specify a version number of
this License, you may choose any version ever published by the Free Software
Foundation.

  10. If you wish to incorporate parts of the Program into other free
programs whose distribution conditions are different, write to the author
to ask for permission.  For software which is copyrighted by the Free
Software Foundation, write to the Free Software Foundation; we sometimes
make exceptions for this.  Our decision will be guided by the two goals
of preserving the free status of all derivatives of our free software and
of promoting the sharing and reuse of software generally.

			    NO WARRANTY

  11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY
FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW.  EXCEPT WHEN
OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES
PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED
OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.  THE ENTIRE RISK AS
TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU.  SHOULD THE
PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING,
REPAIR OR CORRECTION.

  12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING
WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR
REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES,
INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING
OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED
TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY
YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER
PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.

		     END OF TERMS AND CONDITIONS

	    How to Apply These Terms to Your New Programs

  If you develop a new program, and you want it to be of the greatest
possible use to the public, the best way to achieve this is to make it
free software which everyone can redistribute and change under these terms.

  To do so, attach the following notices to the program.  It is safest
to attach them to the start of each source file to most effectively
convey the exclusion of warranty; and each file should have at least
the "copyright" line and a pointer to where the full notice is found.

    <one line to give the program's name and a brief idea of what it does.>
    Copyright (C) <year>  <name of author>

    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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA


Also add information on how to contact you by electronic and paper mail.

If the program is interactive, make it output a short notice like this
when it starts in an interactive mode:

    Gnomovision version 69, Copyright (C) year name of author
    Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'.
    This is free software, and you are welcome to redistribute it
    under certain conditions; type `show c' for details.

The hypothetical commands `show w' and `show c' should show the appropriate
parts of the General Public License.  Of course, the commands you use may
be called something other than `show w' and `show c'; they could even be
mouse-clicks or menu items--whatever suits your program.

You should also get your employer (if you work as a programmer) or your
school, if any, to sign a "copyright disclaimer" for the program, if
necessary.  Here is a sample; alter the names:

  Yoyodyne, Inc., hereby disclaims all copyright interest in the program
  `Gnomovision' (which makes passes at compilers) written by James Hacker.

  <signature of Ty Coon>, 1 April 1989
  Ty Coon, President of Vice

This General Public License does not permit incorporating your program into
proprietary programs.  If your program is a subroutine library, you may
consider it more useful to permit linking proprietary applications with the
library.  If this is what you want to do, use the GNU Library General
Public License instead of this License.
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/* linux/drivers/i2c/busses/i2c-s3c2410.c
 *
 * Copyright (C) 2004,2005 Simtec Electronics
 *	Ben Dooks <ben@simtec.co.uk>
 *
 * S3C2410 I2C Controller
 *
 * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
*/

#include <linux/kernel.h>
#include <linux/module.h>

#include <linux/i2c.h>
#include <linux/i2c-id.h>
#include <linux/init.h>
#include <linux/time.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/err.h>
#include <linux/platform_device.h>
#include <linux/clk.h>
#include <linux/cpufreq.h>

#include <mach/hardware.h>
#include <asm/irq.h>
#include <asm/io.h>

#include <mach/regs-gpio.h>
#include <asm/plat-s3c/regs-iic.h>
#include <asm/plat-s3c/iic.h>

/* i2c controller state */

enum s3c24xx_i2c_state {
	STATE_IDLE,
	STATE_START,
	STATE_READ,
	STATE_WRITE,
	STATE_STOP
};

struct s3c24xx_i2c {
	spinlock_t		lock;
	wait_queue_head_t	wait;

	struct i2c_msg		*msg;
	unsigned int		msg_num;
	unsigned int		msg_idx;
	unsigned int		msg_ptr;

	unsigned int		tx_setup;

	enum s3c24xx_i2c_state	state;
	unsigned long		clkrate;

	void __iomem		*regs;
	struct clk		*clk;
	struct device		*dev;
	struct resource		*irq;
	struct resource		*ioarea;
	struct i2c_adapter	adap;

#ifdef CONFIG_CPU_FREQ
	struct notifier_block	freq_transition;
#endif
};

/* default platform data to use if not supplied in the platform_device
*/

static struct s3c2410_platform_i2c s3c24xx_i2c_default_platform = {
	.flags		= 0,
	.slave_addr	= 0x10,
	.bus_freq	= 100*1000,
	.max_freq	= 400*1000,
	.sda_delay	= S3C2410_IICLC_SDA_DELAY5 | S3C2410_IICLC_FILTER_ON,
};

/* s3c24xx_i2c_is2440()
 *
 * return true is this is an s3c2440
*/

static inline int s3c24xx_i2c_is2440(struct s3c24xx_i2c *i2c)
{
	struct platform_device *pdev = to_platform_device(i2c->dev);

	return !strcmp(pdev->name, "s3c2440-i2c");
}


/* s3c24xx_i2c_get_platformdata
 *
 * get the platform data associated with the given device, or return
 * the default if there is none
*/

static inline struct s3c2410_platform_i2c *s3c24xx_i2c_get_platformdata(struct device *dev)
{
	if (dev->platform_data != NULL)
		return (struct s3c2410_platform_i2c *)dev->platform_data;

	return &s3c24xx_i2c_default_platform;
}

/* s3c24xx_i2c_master_complete
 *
 * complete the message and wake up the caller, using the given return code,
 * or zero to mean ok.
*/

static inline void s3c24xx_i2c_master_complete(struct s3c24xx_i2c *i2c, int ret)
{
	dev_dbg(i2c->dev, "master_complete %d\n", ret);

	i2c->msg_ptr = 0;
	i2c->msg = NULL;
	i2c->msg_idx ++;
	i2c->msg_num = 0;
	if (ret)
		i2c->msg_idx = ret;

	wake_up(&i2c->wait);
}

static inline void s3c24xx_i2c_disable_ack(struct s3c24xx_i2c *i2c)
{
	unsigned long tmp;
	
	tmp = readl(i2c->regs + S3C2410_IICCON);
	writel(tmp & ~S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);

}

static inline void s3c24xx_i2c_enable_ack(struct s3c24xx_i2c *i2c)
{
	unsigned long tmp;
	
	tmp = readl(i2c->regs + S3C2410_IICCON);
	writel(tmp | S3C2410_IICCON_ACKEN, i2c->regs + S3C2410_IICCON);

}

/* irq enable/disable functions */

static inline void s3c24xx_i2c_disable_irq(struct s3c24xx_i2c *i2c)
{
	unsigned long tmp;
	
	tmp = readl(i2c->regs + S3C2410_IICCON);
	writel(tmp & ~S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
}

static inline void s3c24xx_i2c_enable_irq(struct s3c24xx_i2c *i2c)
{
	unsigned long tmp;
	
	tmp = readl(i2c->regs + S3C2410_IICCON);
	writel(tmp | S3C2410_IICCON_IRQEN, i2c->regs + S3C2410_IICCON);
}


/* s3c24xx_i2c_message_start
 *
 * put the start of a message onto the bus 
*/

static void s3c24xx_i2c_message_start(struct s3c24xx_i2c *i2c, 
				      struct i2c_msg *msg)
{
	unsigned int addr = (msg->addr & 0x7f) << 1;
	unsigned long stat;
	unsigned long iiccon;

	stat = 0;
	stat |=  S3C2410_IICSTAT_TXRXEN;

	if (msg->flags & I2C_M_RD) {
		stat |= S3C2410_IICSTAT_MASTER_RX;
		addr |= 1;
	} else
		stat |= S3C2410_IICSTAT_MASTER_TX;

	if (msg->flags & I2C_M_REV_DIR_ADDR)
		addr ^= 1;

	// todo - check for wether ack wanted or not
	s3c24xx_i2c_enable_ack(i2c);

	iiccon = readl(i2c->regs + S3C2410_IICCON);
	writel(stat, i2c->regs + S3C2410_IICSTAT);
	
	dev_dbg(i2c->dev, "START: %08lx to IICSTAT, %02x to DS\n", stat, addr);
	writeb(addr, i2c->regs + S3C2410_IICDS);
	
	/* delay here to ensure the data byte has gotten onto the bus
	 * before the transaction is started */

	ndelay(i2c->tx_setup);

	dev_dbg(i2c->dev, "iiccon, %08lx\n", iiccon);
	writel(iiccon, i2c->regs + S3C2410_IICCON);
	
	stat |=  S3C2410_IICSTAT_START;
	writel(stat, i2c->regs + S3C2410_IICSTAT);
}

static inline void s3c24xx_i2c_stop(struct s3c24xx_i2c *i2c, int ret)
{
	unsigned long iicstat = readl(i2c->regs + S3C2410_IICSTAT);

	dev_dbg(i2c->dev, "STOP\n");

	/* stop the transfer */
	iicstat &= ~ S3C2410_IICSTAT_START;
	writel(iicstat, i2c->regs + S3C2410_IICSTAT);
	
	i2c->state = STATE_STOP;
	
	s3c24xx_i2c_master_complete(i2c, ret);
	s3c24xx_i2c_disable_irq(i2c);
}

/* helper functions to determine the current state in the set of
 * messages we are sending */

/* is_lastmsg()
 *
 * returns TRUE if the current message is the last in the set 
*/

static inline int is_lastmsg(struct s3c24xx_i2c *i2c)
{
	return i2c->msg_idx >= (i2c->msg_num - 1);
}

/* is_msglast
 *
 * returns TRUE if we this is the last byte in the current message
*/

static inline int is_msglast(struct s3c24xx_i2c *i2c)
{
	return i2c->msg_ptr == i2c->msg->len-1;
}

/* is_msgend
 *
 * returns TRUE if we reached the end of the current message
*/

static inline int is_msgend(struct s3c24xx_i2c *i2c)
{
	return i2c->msg_ptr >= i2c->msg->len;
}

/* i2s_s3c_irq_nextbyte
 *
 * process an interrupt and work out what to do
 */

static int i2s_s3c_irq_nextbyte(struct s3c24xx_i2c *i2c, unsigned long iicstat)
{
	unsigned long tmp;
	unsigned char byte;
	int ret = 0;

	switch (i2c->state) {

	case STATE_IDLE:
		dev_err(i2c->dev, "%s: called in STATE_IDLE\n", __func__);
		goto out;
		break;

	case STATE_STOP:
		dev_err(i2c->dev, "%s: called in STATE_STOP\n", __func__);
		s3c24xx_i2c_disable_irq(i2c);		
		goto out_ack;

	case STATE_START:
		/* last thing we did was send a start condition on the
		 * bus, or started a new i2c message
		 */
		
		if (iicstat & S3C2410_IICSTAT_LASTBIT &&
		    !(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
			/* ack was not received... */

			dev_dbg(i2c->dev, "ack was not received\n");
			s3c24xx_i2c_stop(i2c, -ENXIO);
			goto out_ack;
		}

		if (i2c->msg->flags & I2C_M_RD)
			i2c->state = STATE_READ;
		else
			i2c->state = STATE_WRITE;

		/* terminate the transfer if there is nothing to do
		 * as this is used by the i2c probe to find devices. */

		if (is_lastmsg(i2c) && i2c->msg->len == 0) {
			s3c24xx_i2c_stop(i2c, 0);
			goto out_ack;
		}

		if (i2c->state == STATE_READ)
			goto prepare_read;

		/* fall through to the write state, as we will need to 
		 * send a byte as well */

	case STATE_WRITE:
		/* we are writing data to the device... check for the
		 * end of the message, and if so, work out what to do
		 */

		if (!(i2c->msg->flags & I2C_M_IGNORE_NAK)) {
			if (iicstat & S3C2410_IICSTAT_LASTBIT) {
				dev_dbg(i2c->dev, "WRITE: No Ack\n");

				s3c24xx_i2c_stop(i2c, -ECONNREFUSED);
				goto out_ack;
			}
		}

	retry_write:

		if (!is_msgend(i2c)) {
			byte = i2c->msg->buf[i2c->msg_ptr++];
			writeb(byte, i2c->regs + S3C2410_IICDS);

			/* delay after writing the byte to allow the
			 * data setup time on the bus, as writing the
			 * data to the register causes the first bit
			 * to appear on SDA, and SCL will change as
			 * soon as the interrupt is acknowledged */

			ndelay(i2c->tx_setup);

		} else if (!is_lastmsg(i2c)) {
			/* we need to go to the next i2c message */

			dev_dbg(i2c->dev, "WRITE: Next Message\n");

			i2c->msg_ptr = 0;
			i2c->msg_idx ++;
			i2c->msg++;
			
			/* check to see if we need to do another message */
			if (i2c->msg->flags & I2C_M_NOSTART) {

				if (i2c->msg->flags & I2C_M_RD) {
					/* cannot do this, the controller
					 * forces us to send a new START
					 * when we change direction */

					s3c24xx_i2c_stop(i2c, -EINVAL);
				}

				goto retry_write;
			} else {
			
				/* send the new start */
				s3c24xx_i2c_message_start(i2c, i2c->msg);
				i2c->state = STATE_START;
			}

		} else {
			/* send stop */

			s3c24xx_i2c_stop(i2c, 0);
		}
		break;

	case STATE_READ:
		/* we have a byte of data in the data register, do 
		 * something with it, and then work out wether we are
		 * going to do any more read/write
		 */

		byte = readb(i2c->regs + S3C2410_IICDS);
		i2c->msg->buf[i2c->msg_ptr++] = byte;

	prepare_read:
		if (is_msglast(i2c)) {
			/* last byte of buffer */

			if (is_lastmsg(i2c))
				s3c24xx_i2c_disable_ack(i2c);
			
		} else if (is_msgend(i2c)) {
			/* ok, we've read the entire buffer, see if there
			 * is anything else we need to do */

			if (is_lastmsg(i2c)) {
				/* last message, send stop and complete */
				dev_dbg(i2c->dev, "READ: Send Stop\n");

				s3c24xx_i2c_stop(i2c, 0);
			} else {
				/* go to the next transfer */
				dev_dbg(i2c->dev, "READ: Next Transfer\n");

				i2c->msg_ptr = 0;
				i2c->msg_idx++;
				i2c->msg++;
			}
		}

		break;
	}

	/* acknowlegde the IRQ and get back on with the work */

 out_ack:
	tmp = readl(i2c->regs + S3C2410_IICCON);	
	tmp &= ~S3C2410_IICCON_IRQPEND;
	writel(tmp, i2c->regs + S3C2410_IICCON);
 out:
	return ret;
}

/* s3c24xx_i2c_irq
 *
 * top level IRQ servicing routine
*/

static irqreturn_t s3c24xx_i2c_irq(int irqno, void *dev_id)
{
	struct s3c24xx_i2c *i2c = dev_id;
	unsigned long status;
	unsigned long tmp;

	status = readl(i2c->regs + S3C2410_IICSTAT);

	if (status & S3C2410_IICSTAT_ARBITR) {
		// deal with arbitration loss
		dev_err(i2c->dev, "deal with arbitration loss\n");
	}

	if (i2c->state == STATE_IDLE) {
		dev_dbg(i2c->dev, "IRQ: error i2c->state == IDLE\n");

		tmp = readl(i2c->regs + S3C2410_IICCON);	
		tmp &= ~S3C2410_IICCON_IRQPEND;
		writel(tmp, i2c->regs +  S3C2410_IICCON);
		goto out;
	}
	
	/* pretty much this leaves us with the fact that we've
	 * transmitted or received whatever byte we last sent */

	i2s_s3c_irq_nextbyte(i2c, status);

 out:
	return IRQ_HANDLED;
}


/* s3c24xx_i2c_set_master
 *
 * get the i2c bus for a master transaction
*/

static int s3c24xx_i2c_set_master(struct s3c24xx_i2c *i2c)
{
	unsigned long iicstat;
	int timeout = 400;

	while (timeout-- > 0) {
		iicstat = readl(i2c->regs + S3C2410_IICSTAT);
		
		if (!(iicstat & S3C2410_IICSTAT_BUSBUSY))
			return 0;

		msleep(1);
	}

	dev_dbg(i2c->dev, "timeout: GPEDAT is %08x\n",
		__raw_readl(S3C2410_GPEDAT));

	return -ETIMEDOUT;
}

/* s3c24xx_i2c_doxfer
 *
 * this starts an i2c transfer
*/

static int s3c24xx_i2c_doxfer(struct s3c24xx_i2c *i2c, struct i2c_msg *msgs, int num)
{
	unsigned long timeout;
	int ret;

	if (!readl(i2c->regs + S3C2410_IICCON) & S3C2410_IICCON_IRQEN)
		return -EIO;

	ret = s3c24xx_i2c_set_master(i2c);
	if (ret != 0) {
		dev_err(i2c->dev, "cannot get bus (error %d)\n", ret);
		ret = -EAGAIN;
		goto out;
	}

	spin_lock_irq(&i2c->lock);

	i2c->msg     = msgs;
	i2c->msg_num = num;
	i2c->msg_ptr = 0;
	i2c->msg_idx = 0;
	i2c->state   = STATE_START;

	s3c24xx_i2c_enable_irq(i2c);
	s3c24xx_i2c_message_start(i2c, msgs);
	spin_unlock_irq(&i2c->lock);
	
	timeout = wait_event_timeout(i2c->wait, i2c->msg_num == 0, HZ * 5);

	ret = i2c->msg_idx;

	/* having these next two as dev_err() makes life very 
	 * noisy when doing an i2cdetect */

	if (timeout == 0)
		dev_dbg(i2c->dev, "timeout\n");
	else if (ret != num)
		dev_dbg(i2c->dev, "incomplete xfer (%d)\n", ret);

	/* ensure the stop has been through the bus */

	msleep(1);

 out:
	return ret;
}

/* s3c24xx_i2c_xfer
 *
 * first port of call from the i2c bus code when an message needs
 * transferring across the i2c bus.
*/

static int s3c24xx_i2c_xfer(struct i2c_adapter *adap,
			struct i2c_msg *msgs, int num)
{
	struct s3c24xx_i2c *i2c = (struct s3c24xx_i2c *)adap->algo_data;
	int retry;
	int ret;

	for (retry = 0; retry < adap->retries; retry++) {

		ret = s3c24xx_i2c_doxfer(i2c, msgs, num);

		if (ret != -EAGAIN)
			return ret;

		dev_dbg(i2c->dev, "Retrying transmission (%d)\n", retry);

		udelay(100);
	}

	return -EREMOTEIO;
}

/* declare our i2c functionality */
static u32 s3c24xx_i2c_func(struct i2c_adapter *adap)
{
	return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL | I2C_FUNC_PROTOCOL_MANGLING;
}

/* i2c bus registration info */

static const struct i2c_algorithm s3c24xx_i2c_algorithm = {
	.master_xfer		= s3c24xx_i2c_xfer,
	.functionality		= s3c24xx_i2c_func,
};

static struct s3c24xx_i2c s3c24xx_i2c = {
	.lock		= __SPIN_LOCK_UNLOCKED(s3c24xx_i2c.lock),
	.wait		= __WAIT_QUEUE_HEAD_INITIALIZER(s3c24xx_i2c.wait),
	.tx_setup	= 50,
	.adap		= {
		.name			= "s3c2410-i2c",
		.owner			= THIS_MODULE,
		.algo			= &s3c24xx_i2c_algorithm,
		.retries		= 2,
		.class			= I2C_CLASS_HWMON | I2C_CLASS_SPD,
	},
};

/* s3c24xx_i2c_calcdivisor
 *
 * return the divisor settings for a given frequency
*/

static int s3c24xx_i2c_calcdivisor(unsigned long clkin, unsigned int wanted,
				   unsigned int *div1, unsigned int *divs)
{
	unsigned int calc_divs = clkin / wanted;
	unsigned int calc_div1;

	if (calc_divs > (16*16))
		calc_div1 = 512;
	else
		calc_div1 = 16;

	calc_divs += calc_div1-1;
	calc_divs /= calc_div1;

	if (calc_divs == 0)
		calc_divs = 1;
	if (calc_divs > 17)
		calc_divs = 17;

	*divs = calc_divs;
	*div1 = calc_div1;

	return clkin / (calc_divs * calc_div1);
}

/* freq_acceptable
 *
 * test wether a frequency is within the acceptable range of error
*/

static inline int freq_acceptable(unsigned int freq, unsigned int wanted)
{
	int diff = freq - wanted;

	return (diff >= -2 && diff <= 2);
}

/* s3c24xx_i2c_clockrate
 *
 * work out a divisor for the user requested frequency setting,
 * either by the requested frequency, or scanning the acceptable
 * range of frequencies until something is found
*/

static int s3c24xx_i2c_clockrate(struct s3c24xx_i2c *i2c, unsigned int *got)
{
	struct s3c2410_platform_i2c *pdata;
	unsigned long clkin = clk_get_rate(i2c->clk);
	unsigned int divs, div1;
	u32 iiccon;
	int freq;
	int start, end;

	i2c->clkrate = clkin;

	pdata = s3c24xx_i2c_get_platformdata(i2c->adap.dev.parent);
	clkin /= 1000;		/* clkin now in KHz */
     
	dev_dbg(i2c->dev, "pdata %p, freq %lu %lu..%lu\n",
		 pdata, pdata->bus_freq, pdata->min_freq, pdata->max_freq);

	if (pdata->bus_freq != 0) {
		freq = s3c24xx_i2c_calcdivisor(clkin, pdata->bus_freq/1000,
					       &div1, &divs);
		if (freq_acceptable(freq, pdata->bus_freq/1000))
			goto found;
	}

	/* ok, we may have to search for something suitable... */

	start = (pdata->max_freq == 0) ? pdata->bus_freq : pdata->max_freq;
	end = pdata->min_freq;

	start /= 1000;
	end /= 1000;

	/* search loop... */

	for (; start > end; start--) {
		freq = s3c24xx_i2c_calcdivisor(clkin, start, &div1, &divs);
		if (freq_acceptable(freq, start))
			goto found;
	}

	/* cannot find frequency spec */

	return -EINVAL;

 found:
	*got = freq;

	iiccon = readl(i2c->regs + S3C2410_IICCON);
	iiccon &= ~(S3C2410_IICCON_SCALEMASK | S3C2410_IICCON_TXDIV_512);
	iiccon |= (divs-1);

	if (div1 == 512)
		iiccon |= S3C2410_IICCON_TXDIV_512;

	writel(iiccon, i2c->regs + S3C2410_IICCON);

	return 0;
}

#ifdef CONFIG_CPU_FREQ

#define freq_to_i2c(_n) container_of(_n, struct s3c24xx_i2c, freq_transition)

static int s3c24xx_i2c_cpufreq_transition(struct notifier_block *nb,
					  unsigned long val, void *data)
{
	struct s3c24xx_i2c *i2c = freq_to_i2c(nb);
	unsigned long flags;
	unsigned int got;
	int delta_f;
	int ret;

	delta_f = clk_get_rate(i2c->clk) - i2c->clkrate;

	/* if we're post-change and the input clock has slowed down
	 * or at pre-change and the clock is about to speed up, then
	 * adjust our clock rate. <0 is slow, >0 speedup.
	 */

	if ((val == CPUFREQ_POSTCHANGE && delta_f < 0) ||
	    (val == CPUFREQ_PRECHANGE && delta_f > 0)) {
		spin_lock_irqsave(&i2c->lock, flags);
		ret = s3c24xx_i2c_clockrate(i2c, &got);
		spin_unlock_irqrestore(&i2c->lock, flags);

		if (ret < 0)
			dev_err(i2c->dev, "cannot find frequency\n");
		else
			dev_info(i2c->dev, "setting freq %d\n", got);
	}

	return 0;
}

static inline int s3c24xx_i2c_register_cpufreq(struct s3c24xx_i2c *i2c)
{
	i2c->freq_transition.notifier_call = s3c24xx_i2c_cpufreq_transition;

	return cpufreq_register_notifier(&i2c->freq_transition,
					 CPUFREQ_TRANSITION_NOTIFIER);
}

static inline void s3c24xx_i2c_deregister_cpufreq(struct s3c24xx_i2c *i2c)
{
	cpufreq_unregister_notifier(&i2c->freq_transition,
				    CPUFREQ_TRANSITION_NOTIFIER);
}

#else
static inline int s3c24xx_i2c_register_cpufreq(struct s3c24xx_i2c *i2c)
{
	return 0;
}

static inline void s3c24xx_i2c_deregister_cpufreq(struct s3c24xx_i2c *i2c)
{
}
#endif

/* s3c24xx_i2c_init
 *
 * initialise the controller, set the IO lines and frequency 
*/

static int s3c24xx_i2c_init(struct s3c24xx_i2c *i2c)
{
	unsigned long iicon = S3C2410_IICCON_IRQEN | S3C2410_IICCON_ACKEN;
	struct s3c2410_platform_i2c *pdata;
	unsigned int freq;

	/* get the plafrom data */

	pdata = s3c24xx_i2c_get_platformdata(i2c->adap.dev.parent);

	/* inititalise the gpio */

	s3c2410_gpio_cfgpin(S3C2410_GPE15, S3C2410_GPE15_IICSDA);
	s3c2410_gpio_cfgpin(S3C2410_GPE14, S3C2410_GPE14_IICSCL);

	/* write slave address */
	
	writeb(pdata->slave_addr, i2c->regs + S3C2410_IICADD);

	dev_info(i2c->dev, "slave address 0x%02x\n", pdata->slave_addr);

	writel(iicon, i2c->regs + S3C2410_IICCON);

	/* we need to work out the divisors for the clock... */

	if (s3c24xx_i2c_clockrate(i2c, &freq) != 0) {
		writel(0, i2c->regs + S3C2410_IICCON);
		dev_err(i2c->dev, "cannot meet bus frequency required\n");
		return -EINVAL;
	}

	/* todo - check that the i2c lines aren't being dragged anywhere */

	dev_info(i2c->dev, "bus frequency set to %d KHz\n", freq);
	dev_dbg(i2c->dev, "S3C2410_IICCON=0x%02lx\n", iicon);

	/* check for s3c2440 i2c controller  */

	if (s3c24xx_i2c_is2440(i2c)) {
		dev_dbg(i2c->dev, "S3C2440_IICLC=%08x\n", pdata->sda_delay);

		writel(pdata->sda_delay, i2c->regs + S3C2440_IICLC);
	}

	return 0;
}

/* s3c24xx_i2c_probe
 *
 * called by the bus driver when a suitable device is found
*/

static int s3c24xx_i2c_probe(struct platform_device *pdev)
{
	struct s3c24xx_i2c *i2c = &s3c24xx_i2c;
	struct s3c2410_platform_i2c *pdata;
	struct resource *res;
	int ret;

	pdata = s3c24xx_i2c_get_platformdata(&pdev->dev);

	/* find the clock and enable it */

	i2c->dev = &pdev->dev;
	i2c->clk = clk_get(&pdev->dev, "i2c");
	if (IS_ERR(i2c->clk)) {
		dev_err(&pdev->dev, "cannot get clock\n");
		ret = -ENOENT;
		goto err_noclk;
	}

	dev_dbg(&pdev->dev, "clock source %p\n", i2c->clk);

	clk_enable(i2c->clk);

	/* map the registers */

	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
	if (res == NULL) {
		dev_err(&pdev->dev, "cannot find IO resource\n");
		ret = -ENOENT;
		goto err_clk;
	}

	i2c->ioarea = request_mem_region(res->start, (res->end-res->start)+1,
					 pdev->name);

	if (i2c->ioarea == NULL) {
		dev_err(&pdev->dev, "cannot request IO\n");
		ret = -ENXIO;
		goto err_clk;
	}

	i2c->regs = ioremap(res->start, (res->end-res->start)+1);

	if (i2c->regs == NULL) {
		dev_err(&pdev->dev, "cannot map IO\n");
		ret = -ENXIO;
		goto err_ioarea;
	}

	dev_dbg(&pdev->dev, "registers %p (%p, %p)\n", i2c->regs, i2c->ioarea, res);

	/* setup info block for the i2c core */

	i2c->adap.algo_data = i2c;
	i2c->adap.dev.parent = &pdev->dev;

	/* initialise the i2c controller */

	ret = s3c24xx_i2c_init(i2c);
	if (ret != 0)
		goto err_iomap;

	/* find the IRQ for this unit (note, this relies on the init call to
	 * ensure no current IRQs pending 
	 */

	res = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
	if (res == NULL) {
		dev_err(&pdev->dev, "cannot find IRQ\n");
		ret = -ENOENT;
		goto err_iomap;
	}

	ret = request_irq(res->start, s3c24xx_i2c_irq, IRQF_DISABLED,
			  pdev->name, i2c);

	if (ret != 0) {
		dev_err(&pdev->dev, "cannot claim IRQ\n");
		goto err_iomap;
	}

	i2c->irq = res;
		
	dev_dbg(&pdev->dev, "irq resource %p (%lu)\n", res,
		(unsigned long)res->start);

	ret = s3c24xx_i2c_register_cpufreq(i2c);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to register cpufreq notifier\n");
		goto err_irq;
	}

	/* Note, previous versions of the driver used i2c_add_adapter()
	 * to add the bus at any number. We now pass the bus number via
	 * the platform data, so if unset it will now default to always
	 * being bus 0.
	 */

	i2c->adap.nr = pdata->bus_num;

	ret = i2c_add_numbered_adapter(&i2c->adap);
	if (ret < 0) {
		dev_err(&pdev->dev, "failed to add bus to i2c core\n");
		goto err_cpufreq;
	}

	platform_set_drvdata(pdev, i2c);

	dev_info(&pdev->dev, "%s: S3C I2C adapter\n", i2c->adap.dev.bus_id);
	return 0;

 err_cpufreq:
	s3c24xx_i2c_deregister_cpufreq(i2c);

 err_irq:
	free_irq(i2c->irq->start, i2c);

 err_iomap:
	iounmap(i2c->regs);

 err_ioarea:
	release_resource(i2c->ioarea);
	kfree(i2c->ioarea);

 err_clk:
	clk_disable(i2c->clk);
	clk_put(i2c->clk);

 err_noclk:
	return ret;
}

/* s3c24xx_i2c_remove
 *
 * called when device is removed from the bus
*/

static int s3c24xx_i2c_remove(struct platform_device *pdev)
{
	struct s3c24xx_i2c *i2c = platform_get_drvdata(pdev);

	s3c24xx_i2c_deregister_cpufreq(i2c);

	i2c_del_adapter(&i2c->adap);
	free_irq(i2c->irq->start, i2c);

	clk_disable(i2c->clk);
	clk_put(i2c->clk);

	iounmap(i2c->regs);

	release_resource(i2c->ioarea);
	kfree(i2c->ioarea);

	return 0;
}

#ifdef CONFIG_PM
static int s3c24xx_i2c_resume(struct platform_device *dev)
{
	struct s3c24xx_i2c *i2c = platform_get_drvdata(dev);

	if (i2c != NULL)
		s3c24xx_i2c_init(i2c);

	return 0;
}

#else
#define s3c24xx_i2c_resume NULL
#endif

/* device driver for platform bus bits */

static struct platform_driver s3c2410_i2c_driver = {
	.probe		= s3c24xx_i2c_probe,
	.remove		= s3c24xx_i2c_remove,
	.resume		= s3c24xx_i2c_resume,
	.driver		= {
		.owner	= THIS_MODULE,
		.name	= "s3c2410-i2c",
	},
};

static struct platform_driver s3c2440_i2c_driver = {
	.probe		= s3c24xx_i2c_probe,
	.remove		= s3c24xx_i2c_remove,
	.resume		= s3c24xx_i2c_resume,
	.driver		= {
		.owner	= THIS_MODULE,
		.name	= "s3c2440-i2c",
	},
};

static int __init i2c_adap_s3c_init(void)
{
	int ret;

	ret = platform_driver_register(&s3c2410_i2c_driver);
	if (ret == 0) {
		ret = platform_driver_register(&s3c2440_i2c_driver);
		if (ret)
			platform_driver_unregister(&s3c2410_i2c_driver);
	}

	return ret;
}

static void __exit i2c_adap_s3c_exit(void)
{
	platform_driver_unregister(&s3c2410_i2c_driver);
	platform_driver_unregister(&s3c2440_i2c_driver);
}

module_init(i2c_adap_s3c_init);
module_exit(i2c_adap_s3c_exit);

MODULE_DESCRIPTION("S3C24XX I2C Bus driver");
MODULE_AUTHOR("Ben Dooks, <ben@simtec.co.uk>");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:s3c2410-i2c");
MODULE_ALIAS("platform:s3c2440-i2c");