/*
   *   Generic i2c interface for ALSA
   *
   *   (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>

   *   Modified for the ALSA driver by Jaroslav Kysela <perex@perex.cz>

   *
   *   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/init.h>
  #include <linux/slab.h>
  #include <linux/string.h>
  #include <linux/errno.h>
  #include <sound/core.h>
  #include <sound/i2c.h>

  MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");

  MODULE_DESCRIPTION("Generic i2c interface for ALSA");
  MODULE_LICENSE("GPL");

  static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
  				 unsigned char *bytes, int count);
  static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
  				 unsigned char *bytes, int count);
  static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus,
  				 unsigned short addr);
  
  static struct snd_i2c_ops snd_i2c_bit_ops = {

  	.sendbytes = snd_i2c_bit_sendbytes,
  	.readbytes = snd_i2c_bit_readbytes,
  	.probeaddr = snd_i2c_bit_probeaddr,
  };

  static int snd_i2c_bus_free(struct snd_i2c_bus *bus)

  {

  	struct snd_i2c_bus *slave;
  	struct snd_i2c_device *device;

  	if (snd_BUG_ON(!bus))
  		return -EINVAL;

  	while (!list_empty(&bus->devices)) {
  		device = snd_i2c_device(bus->devices.next);
  		snd_i2c_device_free(device);
  	}
  	if (bus->master)
  		list_del(&bus->buses);
  	else {
  		while (!list_empty(&bus->buses)) {
  			slave = snd_i2c_slave_bus(bus->buses.next);
  			snd_device_free(bus->card, slave);
  		}
  	}
  	if (bus->private_free)
  		bus->private_free(bus);
  	kfree(bus);
  	return 0;
  }

  static int snd_i2c_bus_dev_free(struct snd_device *device)

  {

  	struct snd_i2c_bus *bus = device->device_data;

  	return snd_i2c_bus_free(bus);
  }

  int snd_i2c_bus_create(struct snd_card *card, const char *name,
  		       struct snd_i2c_bus *master, struct snd_i2c_bus **ri2c)

  {

  	struct snd_i2c_bus *bus;

  	int err;

  	static struct snd_device_ops ops = {

  		.dev_free =	snd_i2c_bus_dev_free,
  	};
  
  	*ri2c = NULL;

  	bus = kzalloc(sizeof(*bus), GFP_KERNEL);

  	if (bus == NULL)
  		return -ENOMEM;

  	mutex_init(&bus->lock_mutex);

  	INIT_LIST_HEAD(&bus->devices);
  	INIT_LIST_HEAD(&bus->buses);
  	bus->card = card;
  	bus->ops = &snd_i2c_bit_ops;
  	if (master) {
  		list_add_tail(&bus->buses, &master->buses);
  		bus->master = master;
  	}
  	strlcpy(bus->name, name, sizeof(bus->name));

  	err = snd_device_new(card, SNDRV_DEV_BUS, bus, &ops);
  	if (err < 0) {

  		snd_i2c_bus_free(bus);
  		return err;
  	}
  	*ri2c = bus;
  	return 0;
  }

  EXPORT_SYMBOL(snd_i2c_bus_create);

  int snd_i2c_device_create(struct snd_i2c_bus *bus, const char *name,
  			  unsigned char addr, struct snd_i2c_device **rdevice)

  {

  	struct snd_i2c_device *device;

  
  	*rdevice = NULL;

  	if (snd_BUG_ON(!bus))
  		return -EINVAL;

  	device = kzalloc(sizeof(*device), GFP_KERNEL);

  	if (device == NULL)
  		return -ENOMEM;
  	device->addr = addr;
  	strlcpy(device->name, name, sizeof(device->name));
  	list_add_tail(&device->list, &bus->devices);
  	device->bus = bus;
  	*rdevice = device;
  	return 0;
  }

  EXPORT_SYMBOL(snd_i2c_device_create);

  int snd_i2c_device_free(struct snd_i2c_device *device)

  {
  	if (device->bus)
  		list_del(&device->list);
  	if (device->private_free)
  		device->private_free(device);
  	kfree(device);
  	return 0;
  }

  EXPORT_SYMBOL(snd_i2c_device_free);

  int snd_i2c_sendbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)

  {
  	return device->bus->ops->sendbytes(device, bytes, count);
  }

  EXPORT_SYMBOL(snd_i2c_sendbytes);

  int snd_i2c_readbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)

  {
  	return device->bus->ops->readbytes(device, bytes, count);
  }

  EXPORT_SYMBOL(snd_i2c_readbytes);

  int snd_i2c_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)

  {
  	return bus->ops->probeaddr(bus, addr);
  }

  EXPORT_SYMBOL(snd_i2c_probeaddr);

  /*
   *  bit-operations
   */

  static inline void snd_i2c_bit_hw_start(struct snd_i2c_bus *bus)

  {
  	if (bus->hw_ops.bit->start)
  		bus->hw_ops.bit->start(bus);
  }

  static inline void snd_i2c_bit_hw_stop(struct snd_i2c_bus *bus)

  {
  	if (bus->hw_ops.bit->stop)
  		bus->hw_ops.bit->stop(bus);
  }

  static void snd_i2c_bit_direction(struct snd_i2c_bus *bus, int clock, int data)

  {
  	if (bus->hw_ops.bit->direction)
  		bus->hw_ops.bit->direction(bus, clock, data);
  }

  static void snd_i2c_bit_set(struct snd_i2c_bus *bus, int clock, int data)

  {
  	bus->hw_ops.bit->setlines(bus, clock, data);
  }
  
  #if 0

  static int snd_i2c_bit_clock(struct snd_i2c_bus *bus)

  {
  	if (bus->hw_ops.bit->getclock)
  		return bus->hw_ops.bit->getclock(bus);
  	return -ENXIO;
  }
  #endif

  static int snd_i2c_bit_data(struct snd_i2c_bus *bus, int ack)

  {
  	return bus->hw_ops.bit->getdata(bus, ack);
  }

  static void snd_i2c_bit_start(struct snd_i2c_bus *bus)

  {
  	snd_i2c_bit_hw_start(bus);
  	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
  	snd_i2c_bit_set(bus, 1, 1);
  	snd_i2c_bit_set(bus, 1, 0);
  	snd_i2c_bit_set(bus, 0, 0);
  }

  static void snd_i2c_bit_stop(struct snd_i2c_bus *bus)

  {
  	snd_i2c_bit_set(bus, 0, 0);
  	snd_i2c_bit_set(bus, 1, 0);
  	snd_i2c_bit_set(bus, 1, 1);
  	snd_i2c_bit_hw_stop(bus);
  }

  static void snd_i2c_bit_send(struct snd_i2c_bus *bus, int data)

  {
  	snd_i2c_bit_set(bus, 0, data);
  	snd_i2c_bit_set(bus, 1, data);
  	snd_i2c_bit_set(bus, 0, data);
  }

  static int snd_i2c_bit_ack(struct snd_i2c_bus *bus)

  {
  	int ack;
  
  	snd_i2c_bit_set(bus, 0, 1);
  	snd_i2c_bit_set(bus, 1, 1);
  	snd_i2c_bit_direction(bus, 1, 0);	/* SCL - wr, SDA - rd */
  	ack = snd_i2c_bit_data(bus, 1);
  	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
  	snd_i2c_bit_set(bus, 0, 1);
  	return ack ? -EIO : 0;
  }

  static int snd_i2c_bit_sendbyte(struct snd_i2c_bus *bus, unsigned char data)

  {
  	int i, err;
  
  	for (i = 7; i >= 0; i--)
  		snd_i2c_bit_send(bus, !!(data & (1 << i)));

  	err = snd_i2c_bit_ack(bus);
  	if (err < 0)

  		return err;
  	return 0;
  }

  static int snd_i2c_bit_readbyte(struct snd_i2c_bus *bus, int last)

  {
  	int i;
  	unsigned char data = 0;
  
  	snd_i2c_bit_set(bus, 0, 1);
  	snd_i2c_bit_direction(bus, 1, 0);	/* SCL - wr, SDA - rd */
  	for (i = 7; i >= 0; i--) {
  		snd_i2c_bit_set(bus, 1, 1);
  		if (snd_i2c_bit_data(bus, 0))
  			data |= (1 << i);
  		snd_i2c_bit_set(bus, 0, 1);
  	}
  	snd_i2c_bit_direction(bus, 1, 1);	/* SCL - wr, SDA - wr */
  	snd_i2c_bit_send(bus, !!last);
  	return data;
  }

  static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
  				 unsigned char *bytes, int count)

  {

  	struct snd_i2c_bus *bus = device->bus;

  	int err, res = 0;
  
  	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
  		return -EIO;		/* not yet implemented */
  	snd_i2c_bit_start(bus);

  	err = snd_i2c_bit_sendbyte(bus, device->addr << 1);
  	if (err < 0) {

  		snd_i2c_bit_hw_stop(bus);
  		return err;
  	}
  	while (count-- > 0) {

  		err = snd_i2c_bit_sendbyte(bus, *bytes++);
  		if (err < 0) {

  			snd_i2c_bit_hw_stop(bus);
  			return err;
  		}
  		res++;
  	}
  	snd_i2c_bit_stop(bus);
  	return res;
  }

  static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
  				 unsigned char *bytes, int count)

  {

  	struct snd_i2c_bus *bus = device->bus;

  	int err, res = 0;
  
  	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
  		return -EIO;		/* not yet implemented */
  	snd_i2c_bit_start(bus);

  	err = snd_i2c_bit_sendbyte(bus, (device->addr << 1) | 1);
  	if (err < 0) {

  		snd_i2c_bit_hw_stop(bus);
  		return err;
  	}
  	while (count-- > 0) {

  		err = snd_i2c_bit_readbyte(bus, count == 0);
  		if (err < 0) {

  			snd_i2c_bit_hw_stop(bus);
  			return err;
  		}
  		*bytes++ = (unsigned char)err;
  		res++;
  	}
  	snd_i2c_bit_stop(bus);
  	return res;
  }

  static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)

  {
  	int err;
  
  	if (addr & 0x8000)	/* 10-bit address */
  		return -EIO;	/* not yet implemented */
  	if (addr & 0x7f80)	/* invalid address */
  		return -EINVAL;
  	snd_i2c_bit_start(bus);
  	err = snd_i2c_bit_sendbyte(bus, addr << 1);
  	snd_i2c_bit_stop(bus);
  	return err;
  }

  
  static int __init alsa_i2c_init(void)
  {
  	return 0;
  }
  
  static void __exit alsa_i2c_exit(void)
  {
  }
  
  module_init(alsa_i2c_init)
  module_exit(alsa_i2c_exit)