linux/sound/i2c/i2c.c
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   1/*
   2 *   Generic i2c interface for ALSA
   3 *
   4 *   (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
   5 *   Modified for the ALSA driver by Jaroslav Kysela <perex@perex.cz>
   6 *
   7 *   This program is free software; you can redistribute it and/or modify
   8 *   it under the terms of the GNU General Public License as published by
   9 *   the Free Software Foundation; either version 2 of the License, or
  10 *   (at your option) any later version.
  11 *
  12 *   This program is distributed in the hope that it will be useful,
  13 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
  14 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15 *   GNU General Public License for more details.
  16 *
  17 *   You should have received a copy of the GNU General Public License
  18 *   along with this program; if not, write to the Free Software
  19 *   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  20 *
  21 */
  22
  23#include <linux/init.h>
  24#include <linux/slab.h>
  25#include <linux/string.h>
  26#include <linux/errno.h>
  27#include <sound/core.h>
  28#include <sound/i2c.h>
  29
  30MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
  31MODULE_DESCRIPTION("Generic i2c interface for ALSA");
  32MODULE_LICENSE("GPL");
  33
  34static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
  35                                 unsigned char *bytes, int count);
  36static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
  37                                 unsigned char *bytes, int count);
  38static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus,
  39                                 unsigned short addr);
  40
  41static struct snd_i2c_ops snd_i2c_bit_ops = {
  42        .sendbytes = snd_i2c_bit_sendbytes,
  43        .readbytes = snd_i2c_bit_readbytes,
  44        .probeaddr = snd_i2c_bit_probeaddr,
  45};
  46
  47static int snd_i2c_bus_free(struct snd_i2c_bus *bus)
  48{
  49        struct snd_i2c_bus *slave;
  50        struct snd_i2c_device *device;
  51
  52        if (snd_BUG_ON(!bus))
  53                return -EINVAL;
  54        while (!list_empty(&bus->devices)) {
  55                device = snd_i2c_device(bus->devices.next);
  56                snd_i2c_device_free(device);
  57        }
  58        if (bus->master)
  59                list_del(&bus->buses);
  60        else {
  61                while (!list_empty(&bus->buses)) {
  62                        slave = snd_i2c_slave_bus(bus->buses.next);
  63                        snd_device_free(bus->card, slave);
  64                }
  65        }
  66        if (bus->private_free)
  67                bus->private_free(bus);
  68        kfree(bus);
  69        return 0;
  70}
  71
  72static int snd_i2c_bus_dev_free(struct snd_device *device)
  73{
  74        struct snd_i2c_bus *bus = device->device_data;
  75        return snd_i2c_bus_free(bus);
  76}
  77
  78int snd_i2c_bus_create(struct snd_card *card, const char *name,
  79                       struct snd_i2c_bus *master, struct snd_i2c_bus **ri2c)
  80{
  81        struct snd_i2c_bus *bus;
  82        int err;
  83        static struct snd_device_ops ops = {
  84                .dev_free =     snd_i2c_bus_dev_free,
  85        };
  86
  87        *ri2c = NULL;
  88        bus = kzalloc(sizeof(*bus), GFP_KERNEL);
  89        if (bus == NULL)
  90                return -ENOMEM;
  91        mutex_init(&bus->lock_mutex);
  92        INIT_LIST_HEAD(&bus->devices);
  93        INIT_LIST_HEAD(&bus->buses);
  94        bus->card = card;
  95        bus->ops = &snd_i2c_bit_ops;
  96        if (master) {
  97                list_add_tail(&bus->buses, &master->buses);
  98                bus->master = master;
  99        }
 100        strlcpy(bus->name, name, sizeof(bus->name));
 101        err = snd_device_new(card, SNDRV_DEV_BUS, bus, &ops);
 102        if (err < 0) {
 103                snd_i2c_bus_free(bus);
 104                return err;
 105        }
 106        *ri2c = bus;
 107        return 0;
 108}
 109
 110EXPORT_SYMBOL(snd_i2c_bus_create);
 111
 112int snd_i2c_device_create(struct snd_i2c_bus *bus, const char *name,
 113                          unsigned char addr, struct snd_i2c_device **rdevice)
 114{
 115        struct snd_i2c_device *device;
 116
 117        *rdevice = NULL;
 118        if (snd_BUG_ON(!bus))
 119                return -EINVAL;
 120        device = kzalloc(sizeof(*device), GFP_KERNEL);
 121        if (device == NULL)
 122                return -ENOMEM;
 123        device->addr = addr;
 124        strlcpy(device->name, name, sizeof(device->name));
 125        list_add_tail(&device->list, &bus->devices);
 126        device->bus = bus;
 127        *rdevice = device;
 128        return 0;
 129}
 130
 131EXPORT_SYMBOL(snd_i2c_device_create);
 132
 133int snd_i2c_device_free(struct snd_i2c_device *device)
 134{
 135        if (device->bus)
 136                list_del(&device->list);
 137        if (device->private_free)
 138                device->private_free(device);
 139        kfree(device);
 140        return 0;
 141}
 142
 143EXPORT_SYMBOL(snd_i2c_device_free);
 144
 145int snd_i2c_sendbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
 146{
 147        return device->bus->ops->sendbytes(device, bytes, count);
 148}
 149
 150EXPORT_SYMBOL(snd_i2c_sendbytes);
 151
 152int snd_i2c_readbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
 153{
 154        return device->bus->ops->readbytes(device, bytes, count);
 155}
 156
 157EXPORT_SYMBOL(snd_i2c_readbytes);
 158
 159int snd_i2c_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
 160{
 161        return bus->ops->probeaddr(bus, addr);
 162}
 163
 164EXPORT_SYMBOL(snd_i2c_probeaddr);
 165
 166/*
 167 *  bit-operations
 168 */
 169
 170static inline void snd_i2c_bit_hw_start(struct snd_i2c_bus *bus)
 171{
 172        if (bus->hw_ops.bit->start)
 173                bus->hw_ops.bit->start(bus);
 174}
 175
 176static inline void snd_i2c_bit_hw_stop(struct snd_i2c_bus *bus)
 177{
 178        if (bus->hw_ops.bit->stop)
 179                bus->hw_ops.bit->stop(bus);
 180}
 181
 182static void snd_i2c_bit_direction(struct snd_i2c_bus *bus, int clock, int data)
 183{
 184        if (bus->hw_ops.bit->direction)
 185                bus->hw_ops.bit->direction(bus, clock, data);
 186}
 187
 188static void snd_i2c_bit_set(struct snd_i2c_bus *bus, int clock, int data)
 189{
 190        bus->hw_ops.bit->setlines(bus, clock, data);
 191}
 192
 193#if 0
 194static int snd_i2c_bit_clock(struct snd_i2c_bus *bus)
 195{
 196        if (bus->hw_ops.bit->getclock)
 197                return bus->hw_ops.bit->getclock(bus);
 198        return -ENXIO;
 199}
 200#endif
 201
 202static int snd_i2c_bit_data(struct snd_i2c_bus *bus, int ack)
 203{
 204        return bus->hw_ops.bit->getdata(bus, ack);
 205}
 206
 207static void snd_i2c_bit_start(struct snd_i2c_bus *bus)
 208{
 209        snd_i2c_bit_hw_start(bus);
 210        snd_i2c_bit_direction(bus, 1, 1);       /* SCL - wr, SDA - wr */
 211        snd_i2c_bit_set(bus, 1, 1);
 212        snd_i2c_bit_set(bus, 1, 0);
 213        snd_i2c_bit_set(bus, 0, 0);
 214}
 215
 216static void snd_i2c_bit_stop(struct snd_i2c_bus *bus)
 217{
 218        snd_i2c_bit_set(bus, 0, 0);
 219        snd_i2c_bit_set(bus, 1, 0);
 220        snd_i2c_bit_set(bus, 1, 1);
 221        snd_i2c_bit_hw_stop(bus);
 222}
 223
 224static void snd_i2c_bit_send(struct snd_i2c_bus *bus, int data)
 225{
 226        snd_i2c_bit_set(bus, 0, data);
 227        snd_i2c_bit_set(bus, 1, data);
 228        snd_i2c_bit_set(bus, 0, data);
 229}
 230
 231static int snd_i2c_bit_ack(struct snd_i2c_bus *bus)
 232{
 233        int ack;
 234
 235        snd_i2c_bit_set(bus, 0, 1);
 236        snd_i2c_bit_set(bus, 1, 1);
 237        snd_i2c_bit_direction(bus, 1, 0);       /* SCL - wr, SDA - rd */
 238        ack = snd_i2c_bit_data(bus, 1);
 239        snd_i2c_bit_direction(bus, 1, 1);       /* SCL - wr, SDA - wr */
 240        snd_i2c_bit_set(bus, 0, 1);
 241        return ack ? -EIO : 0;
 242}
 243
 244static int snd_i2c_bit_sendbyte(struct snd_i2c_bus *bus, unsigned char data)
 245{
 246        int i, err;
 247
 248        for (i = 7; i >= 0; i--)
 249                snd_i2c_bit_send(bus, !!(data & (1 << i)));
 250        err = snd_i2c_bit_ack(bus);
 251        if (err < 0)
 252                return err;
 253        return 0;
 254}
 255
 256static int snd_i2c_bit_readbyte(struct snd_i2c_bus *bus, int last)
 257{
 258        int i;
 259        unsigned char data = 0;
 260
 261        snd_i2c_bit_set(bus, 0, 1);
 262        snd_i2c_bit_direction(bus, 1, 0);       /* SCL - wr, SDA - rd */
 263        for (i = 7; i >= 0; i--) {
 264                snd_i2c_bit_set(bus, 1, 1);
 265                if (snd_i2c_bit_data(bus, 0))
 266                        data |= (1 << i);
 267                snd_i2c_bit_set(bus, 0, 1);
 268        }
 269        snd_i2c_bit_direction(bus, 1, 1);       /* SCL - wr, SDA - wr */
 270        snd_i2c_bit_send(bus, !!last);
 271        return data;
 272}
 273
 274static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
 275                                 unsigned char *bytes, int count)
 276{
 277        struct snd_i2c_bus *bus = device->bus;
 278        int err, res = 0;
 279
 280        if (device->flags & SND_I2C_DEVICE_ADDRTEN)
 281                return -EIO;            /* not yet implemented */
 282        snd_i2c_bit_start(bus);
 283        err = snd_i2c_bit_sendbyte(bus, device->addr << 1);
 284        if (err < 0) {
 285                snd_i2c_bit_hw_stop(bus);
 286                return err;
 287        }
 288        while (count-- > 0) {
 289                err = snd_i2c_bit_sendbyte(bus, *bytes++);
 290                if (err < 0) {
 291                        snd_i2c_bit_hw_stop(bus);
 292                        return err;
 293                }
 294                res++;
 295        }
 296        snd_i2c_bit_stop(bus);
 297        return res;
 298}
 299
 300static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
 301                                 unsigned char *bytes, int count)
 302{
 303        struct snd_i2c_bus *bus = device->bus;
 304        int err, res = 0;
 305
 306        if (device->flags & SND_I2C_DEVICE_ADDRTEN)
 307                return -EIO;            /* not yet implemented */
 308        snd_i2c_bit_start(bus);
 309        err = snd_i2c_bit_sendbyte(bus, (device->addr << 1) | 1);
 310        if (err < 0) {
 311                snd_i2c_bit_hw_stop(bus);
 312                return err;
 313        }
 314        while (count-- > 0) {
 315                err = snd_i2c_bit_readbyte(bus, count == 0);
 316                if (err < 0) {
 317                        snd_i2c_bit_hw_stop(bus);
 318                        return err;
 319                }
 320                *bytes++ = (unsigned char)err;
 321                res++;
 322        }
 323        snd_i2c_bit_stop(bus);
 324        return res;
 325}
 326
 327static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
 328{
 329        int err;
 330
 331        if (addr & 0x8000)      /* 10-bit address */
 332                return -EIO;    /* not yet implemented */
 333        if (addr & 0x7f80)      /* invalid address */
 334                return -EINVAL;
 335        snd_i2c_bit_start(bus);
 336        err = snd_i2c_bit_sendbyte(bus, addr << 1);
 337        snd_i2c_bit_stop(bus);
 338        return err;
 339}
 340
 341
 342static int __init alsa_i2c_init(void)
 343{
 344        return 0;
 345}
 346
 347static void __exit alsa_i2c_exit(void)
 348{
 349}
 350
 351module_init(alsa_i2c_init)
 352module_exit(alsa_i2c_exit)
 353