i2c.c

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/*
 *   Generic i2c interface for ALSA
 *
 *   (c) 1998 Gerd Knorr <[email protected]>
 *   Modified for the ALSA driver by Jaroslav Kysela <[email protected]>
 *
 *   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/module.h>
#include <linux/string.h>
#include <linux/errno.h>
#include <sound/core.h>
#include <sound/i2c.h>

MODULE_AUTHOR("Jaroslav Kysela <[email protected]>");
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)