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/module.h>
  26#include <linux/string.h>
  27#include <linux/errno.h>
  28#include <sound/core.h>
  29#include <sound/i2c.h>
  30
  31MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
  32MODULE_DESCRIPTION("Generic i2c interface for ALSA");
  33MODULE_LICENSE("GPL");
  34
  35static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
  36                                 unsigned char *bytes, int count);
  37static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
  38                                 unsigned char *bytes, int count);
  39static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus,
  40                                 unsigned short addr);
  41
  42static struct snd_i2c_ops snd_i2c_bit_ops = {
  43        .sendbytes = snd_i2c_bit_sendbytes,
  44        .readbytes = snd_i2c_bit_readbytes,
  45        .probeaddr = snd_i2c_bit_probeaddr,
  46};
  47
  48static int snd_i2c_bus_free(struct snd_i2c_bus *bus)
  49{
  50        struct snd_i2c_bus *slave;
  51        struct snd_i2c_device *device;
  52
  53        if (snd_BUG_ON(!bus))
  54                return -EINVAL;
  55        while (!list_empty(&bus->devices)) {
  56                device = snd_i2c_device(bus->devices.next);
  57                snd_i2c_device_free(device);
  58        }
  59        if (bus->master)
  60                list_del(&bus->buses);
  61        else {
  62                while (!list_empty(&bus->buses)) {
  63                        slave = snd_i2c_slave_bus(bus->buses.next);
  64                        snd_device_free(bus->card, slave);
  65                }
  66        }
  67        if (bus->private_free)
  68                bus->private_free(bus);
  69        kfree(bus);
  70        return 0;
  71}
  72
  73static int snd_i2c_bus_dev_free(struct snd_device *device)
  74{
  75        struct snd_i2c_bus *bus = device->device_data;
  76        return snd_i2c_bus_free(bus);
  77}
  78
  79int snd_i2c_bus_create(struct snd_card *card, const char *name,
  80                       struct snd_i2c_bus *master, struct snd_i2c_bus **ri2c)
  81{
  82        struct snd_i2c_bus *bus;
  83        int err;
  84        static struct snd_device_ops ops = {
  85                .dev_free =     snd_i2c_bus_dev_free,
  86        };
  87
  88        *ri2c = NULL;
  89        bus = kzalloc(sizeof(*bus), GFP_KERNEL);
  90        if (bus == NULL)
  91                return -ENOMEM;
  92        mutex_init(&bus->lock_mutex);
  93        INIT_LIST_HEAD(&bus->devices);
  94        INIT_LIST_HEAD(&bus->buses);
  95        bus->card = card;
  96        bus->ops = &snd_i2c_bit_ops;
  97        if (master) {
  98                list_add_tail(&bus->buses, &master->buses);
  99                bus->master = master;
 100        }
 101        strlcpy(bus->name, name, sizeof(bus->name));
 102        err = snd_device_new(card, SNDRV_DEV_BUS, bus, &ops);
 103        if (err < 0) {
 104                snd_i2c_bus_free(bus);
 105                return err;
 106        }
 107        *ri2c = bus;
 108        return 0;
 109}
 110
 111EXPORT_SYMBOL(snd_i2c_bus_create);
 112
 113int snd_i2c_device_create(struct snd_i2c_bus *bus, const char *name,
 114                          unsigned char addr, struct snd_i2c_device **rdevice)
 115{
 116        struct snd_i2c_device *device;
 117
 118        *rdevice = NULL;
 119        if (snd_BUG_ON(!bus))
 120                return -EINVAL;
 121        device = kzalloc(sizeof(*device), GFP_KERNEL);
 122        if (device == NULL)
 123                return -ENOMEM;
 124        device->addr = addr;
 125        strlcpy(device->name, name, sizeof(device->name));
 126        list_add_tail(&device->list, &bus->devices);
 127        device->bus = bus;
 128        *rdevice = device;
 129        return 0;
 130}
 131
 132EXPORT_SYMBOL(snd_i2c_device_create);
 133
 134int snd_i2c_device_free(struct snd_i2c_device *device)
 135{
 136        if (device->bus)
 137                list_del(&device->list);
 138        if (device->private_free)
 139                device->private_free(device);
 140        kfree(device);
 141        return 0;
 142}
 143
 144EXPORT_SYMBOL(snd_i2c_device_free);
 145
 146int snd_i2c_sendbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
 147{
 148        return device->bus->ops->sendbytes(device, bytes, count);
 149}
 150
 151EXPORT_SYMBOL(snd_i2c_sendbytes);
 152
 153int snd_i2c_readbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
 154{
 155        return device->bus->ops->readbytes(device, bytes, count);
 156}
 157
 158EXPORT_SYMBOL(snd_i2c_readbytes);
 159
 160int snd_i2c_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
 161{
 162        return bus->ops->probeaddr(bus, addr);
 163}
 164
 165EXPORT_SYMBOL(snd_i2c_probeaddr);
 166
 167/*
 168 *  bit-operations
 169 */
 170
 171static inline void snd_i2c_bit_hw_start(struct snd_i2c_bus *bus)
 172{
 173        if (bus->hw_ops.bit->start)
 174                bus->hw_ops.bit->start(bus);
 175}
 176
 177static inline void snd_i2c_bit_hw_stop(struct snd_i2c_bus *bus)
 178{
 179        if (bus->hw_ops.bit->stop)
 180                bus->hw_ops.bit->stop(bus);
 181}
 182
 183static void snd_i2c_bit_direction(struct snd_i2c_bus *bus, int clock, int data)
 184{
 185        if (bus->hw_ops.bit->direction)
 186                bus->hw_ops.bit->direction(bus, clock, data);
 187}
 188
 189static void snd_i2c_bit_set(struct snd_i2c_bus *bus, int clock, int data)
 190{
 191        bus->hw_ops.bit->setlines(bus, clock, data);
 192}
 193
 194#if 0
 195static int snd_i2c_bit_clock(struct snd_i2c_bus *bus)
 196{
 197        if (bus->hw_ops.bit->getclock)
 198                return bus->hw_ops.bit->getclock(bus);
 199        return -ENXIO;
 200}
 201#endif
 202
 203static int snd_i2c_bit_data(struct snd_i2c_bus *bus, int ack)
 204{
 205        return bus->hw_ops.bit->getdata(bus, ack);
 206}
 207
 208static void snd_i2c_bit_start(struct snd_i2c_bus *bus)
 209{
 210        snd_i2c_bit_hw_start(bus);
 211        snd_i2c_bit_direction(bus, 1, 1);       /* SCL - wr, SDA - wr */
 212        snd_i2c_bit_set(bus, 1, 1);
 213        snd_i2c_bit_set(bus, 1, 0);
 214        snd_i2c_bit_set(bus, 0, 0);
 215}
 216
 217static void snd_i2c_bit_stop(struct snd_i2c_bus *bus)
 218{
 219        snd_i2c_bit_set(bus, 0, 0);
 220        snd_i2c_bit_set(bus, 1, 0);
 221        snd_i2c_bit_set(bus, 1, 1);
 222        snd_i2c_bit_hw_stop(bus);
 223}
 224
 225static void snd_i2c_bit_send(struct snd_i2c_bus *bus, int data)
 226{
 227        snd_i2c_bit_set(bus, 0, data);
 228        snd_i2c_bit_set(bus, 1, data);
 229        snd_i2c_bit_set(bus, 0, data);
 230}
 231
 232static int snd_i2c_bit_ack(struct snd_i2c_bus *bus)
 233{
 234        int ack;
 235
 236        snd_i2c_bit_set(bus, 0, 1);
 237        snd_i2c_bit_set(bus, 1, 1);
 238        snd_i2c_bit_direction(bus, 1, 0);       /* SCL - wr, SDA - rd */
 239        ack = snd_i2c_bit_data(bus, 1);
 240        snd_i2c_bit_direction(bus, 1, 1);       /* SCL - wr, SDA - wr */
 241        snd_i2c_bit_set(bus, 0, 1);
 242        return ack ? -EIO : 0;
 243}
 244
 245static int snd_i2c_bit_sendbyte(struct snd_i2c_bus *bus, unsigned char data)
 246{
 247        int i, err;
 248
 249        for (i = 7; i >= 0; i--)
 250                snd_i2c_bit_send(bus, !!(data & (1 << i)));
 251        err = snd_i2c_bit_ack(bus);
 252        if (err < 0)
 253                return err;
 254        return 0;
 255}
 256
 257static int snd_i2c_bit_readbyte(struct snd_i2c_bus *bus, int last)
 258{
 259        int i;
 260        unsigned char data = 0;
 261
 262        snd_i2c_bit_set(bus, 0, 1);
 263        snd_i2c_bit_direction(bus, 1, 0);       /* SCL - wr, SDA - rd */
 264        for (i = 7; i >= 0; i--) {
 265                snd_i2c_bit_set(bus, 1, 1);
 266                if (snd_i2c_bit_data(bus, 0))
 267                        data |= (1 << i);
 268                snd_i2c_bit_set(bus, 0, 1);
 269        }
 270        snd_i2c_bit_direction(bus, 1, 1);       /* SCL - wr, SDA - wr */
 271        snd_i2c_bit_send(bus, !!last);
 272        return data;
 273}
 274
 275static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
 276                                 unsigned char *bytes, int count)
 277{
 278        struct snd_i2c_bus *bus = device->bus;
 279        int err, res = 0;
 280
 281        if (device->flags & SND_I2C_DEVICE_ADDRTEN)
 282                return -EIO;            /* not yet implemented */
 283        snd_i2c_bit_start(bus);
 284        err = snd_i2c_bit_sendbyte(bus, device->addr << 1);
 285        if (err < 0) {
 286                snd_i2c_bit_hw_stop(bus);
 287                return err;
 288        }
 289        while (count-- > 0) {
 290                err = snd_i2c_bit_sendbyte(bus, *bytes++);
 291                if (err < 0) {
 292                        snd_i2c_bit_hw_stop(bus);
 293                        return err;
 294                }
 295                res++;
 296        }
 297        snd_i2c_bit_stop(bus);
 298        return res;
 299}
 300
 301static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
 302                                 unsigned char *bytes, int count)
 303{
 304        struct snd_i2c_bus *bus = device->bus;
 305        int err, res = 0;
 306
 307        if (device->flags & SND_I2C_DEVICE_ADDRTEN)
 308                return -EIO;            /* not yet implemented */
 309        snd_i2c_bit_start(bus);
 310        err = snd_i2c_bit_sendbyte(bus, (device->addr << 1) | 1);
 311        if (err < 0) {
 312                snd_i2c_bit_hw_stop(bus);
 313                return err;
 314        }
 315        while (count-- > 0) {
 316                err = snd_i2c_bit_readbyte(bus, count == 0);
 317                if (err < 0) {
 318                        snd_i2c_bit_hw_stop(bus);
 319                        return err;
 320                }
 321                *bytes++ = (unsigned char)err;
 322                res++;
 323        }
 324        snd_i2c_bit_stop(bus);
 325        return res;
 326}
 327
 328static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
 329{
 330        int err;
 331
 332        if (addr & 0x8000)      /* 10-bit address */
 333                return -EIO;    /* not yet implemented */
 334        if (addr & 0x7f80)      /* invalid address */
 335                return -EINVAL;
 336        snd_i2c_bit_start(bus);
 337        err = snd_i2c_bit_sendbyte(bus, addr << 1);
 338        snd_i2c_bit_stop(bus);
 339        return err;
 340}
 341
 342
 343static int __init alsa_i2c_init(void)
 344{
 345        return 0;
 346}
 347
 348static void __exit alsa_i2c_exit(void)
 349{
 350}
 351
 352module_init(alsa_i2c_init)
 353module_exit(alsa_i2c_exit)
 354
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