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i2c.c

/*
 *   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(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;

      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);
      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));
      if ((err = snd_device_new(card, SNDRV_DEV_BUS, bus, &ops)) < 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;
      snd_assert(bus != NULL, 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)));
      if ((err = snd_i2c_bit_ack(bus)) < 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);
      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(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);
      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(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)

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