text: /*
   *   Generic i2c interface for ALSA
   *
   *   (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
   *   Modified for the ALSA driver by Jaroslav Kysela <perex@suse.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 <sound/driver.h>
  #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@suse.cz>");
  MODULE_DESCRIPTION("Generic i2c interface for ALSA");
  MODULE_LICENSE("GPL");
  
  static int snd_i2c_bit_sendbytes(snd_i2c_device_t *device, unsigned char *bytes, int count);
  static int snd_i2c_bit_readbytes(snd_i2c_device_t *device, unsigned char *bytes, int count);
  static int snd_i2c_bit_probeaddr(snd_i2c_bus_t *bus, unsigned short addr);
  
  static snd_i2c_ops_t 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(snd_i2c_bus_t *bus)
  {
  	snd_i2c_bus_t *slave;
  	snd_i2c_device_t *device;
  
  	snd_assert(bus != NULL, 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);
  	snd_magic_kfree(bus);
  	return 0;
  }
  
  static int snd_i2c_bus_dev_free(snd_device_t *device)
  {
  	snd_i2c_bus_t *bus = snd_magic_cast(snd_i2c_bus_t, device->device_data, return -ENXIO);
  	return snd_i2c_bus_free(bus);
  }
  
  int snd_i2c_bus_create(snd_card_t *card, const char *name, snd_i2c_bus_t *master, snd_i2c_bus_t **ri2c)
  {
  	snd_i2c_bus_t *bus;
  	int err;
  	static snd_device_ops_t ops = {
  		.dev_free =	snd_i2c_bus_dev_free,
  	};
  
  	*ri2c = NULL;
  	bus = (snd_i2c_bus_t *)snd_magic_kcalloc(snd_i2c_bus_t, 0, GFP_KERNEL);
  	if (bus == NULL)
  		return -ENOMEM;
  	spin_lock_init(&bus->lock);
  	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));
  	if ((err = snd_device_new(card, SNDRV_DEV_LOWLEVEL, bus, &ops)) < 0) {
  		snd_i2c_bus_free(bus);
  		return err;
  	}
  	*ri2c = bus;
  	return 0;
  }
  
  int snd_i2c_device_create(snd_i2c_bus_t *bus, const char *name, unsigned char addr, snd_i2c_device_t **rdevice)
  {
  	snd_i2c_device_t *device;
  
  	*rdevice = NULL;
  	snd_assert(bus != NULL, return -EINVAL);
  	device = (snd_i2c_device_t *)snd_magic_kcalloc(snd_i2c_device_t, 0, 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;
  }
  
  int snd_i2c_device_free(snd_i2c_device_t *device)
  {
  	if (device->bus)
  		list_del(&device->list);
  	if (device->private_free)
  		device->private_free(device);
  	snd_magic_kfree(device);
  	return 0;
  }
  
  int snd_i2c_sendbytes(snd_i2c_device_t *device, unsigned char *bytes, int count)
  {
  	return device->bus->ops->sendbytes(device, bytes, count);
  }
  
  
  int snd_i2c_readbytes(snd_i2c_device_t *device, unsigned char *bytes, int count)
  {
  	return device->bus->ops->readbytes(device, bytes, count);
  }
  
  int snd_i2c_probeaddr(snd_i2c_bus_t *bus, unsigned short addr)
  {
  	return bus->ops->probeaddr(bus, addr);
  }
  
  /*
   *  bit-operations
   */
  
  static inline void snd_i2c_bit_hw_start(snd_i2c_bus_t *bus)
  {
  	if (bus->hw_ops.bit->start)
  		bus->hw_ops.bit->start(bus);
  }
  
  static inline void snd_i2c_bit_hw_stop(snd_i2c_bus_t *bus)
  {
  	if (bus->hw_ops.bit->stop)
  		bus->hw_ops.bit->stop(bus);
  }
  
  static void snd_i2c_bit_direction(snd_i2c_bus_t *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(snd_i2c_bus_t *bus, int clock, int data)
  {
  	bus->hw_ops.bit->setlines(bus, clock, data);
  }
  
  #if 0
  static int snd_i2c_bit_clock(snd_i2c_bus_t *bus)
  {
  	if (bus->hw_ops.bit->getclock)
  		return bus->hw_ops.bit->getclock(bus);
  	return -ENXIO;
  }
  #endif
  
  static int snd_i2c_bit_data(snd_i2c_bus_t *bus, int ack)
  {
  	return bus->hw_ops.bit->getdata(bus, ack);
  }
  
  static void snd_i2c_bit_start(snd_i2c_bus_t *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(snd_i2c_bus_t *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(snd_i2c_bus_t *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(snd_i2c_bus_t *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(snd_i2c_bus_t *bus, unsigned char data)
  {
  	int i, err;
  
  	for (i = 7; i >= 0; i--)
  		snd_i2c_bit_send(bus, !!(data & (1 << i)));
  	if ((err = snd_i2c_bit_ack(bus)) < 0)
  		return err;
  	return 0;
  }
  
  static int snd_i2c_bit_readbyte(snd_i2c_bus_t *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(snd_i2c_device_t *device, unsigned char *bytes, int count)
  {
  	snd_i2c_bus_t *bus = device->bus;
  	int err, res = 0;
  
  	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
  		return -EIO;		/* not yet implemented */
  	snd_i2c_bit_start(bus);
  	if ((err = snd_i2c_bit_sendbyte(bus, device->addr << 1)) < 0) {
  		snd_i2c_bit_hw_stop(bus);
  		return err;
  	}
  	while (count-- > 0) {
  		if ((err = snd_i2c_bit_sendbyte(bus, *bytes++)) < 0) {
  			snd_i2c_bit_hw_stop(bus);
  			return err;
  		}
  		res++;
  	}
  	snd_i2c_bit_stop(bus);
  	return res;
  }
  
  static int snd_i2c_bit_readbytes(snd_i2c_device_t *device, unsigned char *bytes, int count)
  {
  	snd_i2c_bus_t *bus = device->bus;
  	int err, res = 0;
  
  	if (device->flags & SND_I2C_DEVICE_ADDRTEN)
  		return -EIO;		/* not yet implemented */
  	snd_i2c_bit_start(bus);
  	if ((err = snd_i2c_bit_sendbyte(bus, (device->addr << 1) | 1)) < 0) {
  		snd_i2c_bit_hw_stop(bus);
  		return err;
  	}
  	while (count-- > 0) {
  		if ((err = snd_i2c_bit_readbyte(bus, count == 0)) < 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(snd_i2c_bus_t *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;
  }
  
  EXPORT_SYMBOL(snd_i2c_bus_create);
  EXPORT_SYMBOL(snd_i2c_device_create);
  EXPORT_SYMBOL(snd_i2c_device_free);
  EXPORT_SYMBOL(snd_i2c_sendbytes);
  EXPORT_SYMBOL(snd_i2c_readbytes);
  EXPORT_SYMBOL(snd_i2c_probeaddr);
  
  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)
  