sound/i2c/i2c.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  *   Generic i2c interface for ALSA
0004  *
0005  *   (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
0006  *   Modified for the ALSA driver by Jaroslav Kysela <perex@perex.cz>
0007  */
0008
0009 #include <linux/init.h>
0010 #include <linux/slab.h>
0011 #include <linux/module.h>
0012 #include <linux/string.h>
0013 #include <linux/errno.h>
0014 #include <sound/core.h>
0015 #include <sound/i2c.h>
0016
0017 MODULE_AUTHOR("Jaroslav Kysela <perex@perex.cz>");
0018 MODULE_DESCRIPTION("Generic i2c interface for ALSA");
0019 MODULE_LICENSE("GPL");
0020
0021 static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
0022                  unsigned char *bytes, int count);
0023 static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
0024                  unsigned char *bytes, int count);
0025 static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus,
0026                  unsigned short addr);
0027
0028 static const struct snd_i2c_ops snd_i2c_bit_ops = {
0029     .sendbytes = snd_i2c_bit_sendbytes,
0030     .readbytes = snd_i2c_bit_readbytes,
0031     .probeaddr = snd_i2c_bit_probeaddr,
0032 };
0033
0034 static int snd_i2c_bus_free(struct snd_i2c_bus *bus)
0035 {
0036     struct snd_i2c_bus *slave;
0037     struct snd_i2c_device *device;
0038
0039     if (snd_BUG_ON(!bus))
0040         return -EINVAL;
0041     while (!list_empty(&bus->devices)) {
0042         device = snd_i2c_device(bus->devices.next);
0043         snd_i2c_device_free(device);
0044     }
0045     if (bus->master)
0046         list_del(&bus->buses);
0047     else {
0048         while (!list_empty(&bus->buses)) {
0049             slave = snd_i2c_slave_bus(bus->buses.next);
0050             snd_device_free(bus->card, slave);
0051         }
0052     }
0053     if (bus->private_free)
0054         bus->private_free(bus);
0055     kfree(bus);
0056     return 0;
0057 }
0058
0059 static int snd_i2c_bus_dev_free(struct snd_device *device)
0060 {
0061     struct snd_i2c_bus *bus = device->device_data;
0062     return snd_i2c_bus_free(bus);
0063 }
0064
0065 int snd_i2c_bus_create(struct snd_card *card, const char *name,
0066                struct snd_i2c_bus *master, struct snd_i2c_bus **ri2c)
0067 {
0068     struct snd_i2c_bus *bus;
0069     int err;
0070     static const struct snd_device_ops ops = {
0071         .dev_free = snd_i2c_bus_dev_free,
0072     };
0073
0074     *ri2c = NULL;
0075     bus = kzalloc(sizeof(*bus), GFP_KERNEL);
0076     if (bus == NULL)
0077         return -ENOMEM;
0078     mutex_init(&bus->lock_mutex);
0079     INIT_LIST_HEAD(&bus->devices);
0080     INIT_LIST_HEAD(&bus->buses);
0081     bus->card = card;
0082     bus->ops = &snd_i2c_bit_ops;
0083     if (master) {
0084         list_add_tail(&bus->buses, &master->buses);
0085         bus->master = master;
0086     }
0087     strscpy(bus->name, name, sizeof(bus->name));
0088     err = snd_device_new(card, SNDRV_DEV_BUS, bus, &ops);
0089     if (err < 0) {
0090         snd_i2c_bus_free(bus);
0091         return err;
0092     }
0093     *ri2c = bus;
0094     return 0;
0095 }
0096
0097 EXPORT_SYMBOL(snd_i2c_bus_create);
0098
0099 int snd_i2c_device_create(struct snd_i2c_bus *bus, const char *name,
0100               unsigned char addr, struct snd_i2c_device **rdevice)
0101 {
0102     struct snd_i2c_device *device;
0103
0104     *rdevice = NULL;
0105     if (snd_BUG_ON(!bus))
0106         return -EINVAL;
0107     device = kzalloc(sizeof(*device), GFP_KERNEL);
0108     if (device == NULL)
0109         return -ENOMEM;
0110     device->addr = addr;
0111     strscpy(device->name, name, sizeof(device->name));
0112     list_add_tail(&device->list, &bus->devices);
0113     device->bus = bus;
0114     *rdevice = device;
0115     return 0;
0116 }
0117
0118 EXPORT_SYMBOL(snd_i2c_device_create);
0119
0120 int snd_i2c_device_free(struct snd_i2c_device *device)
0121 {
0122     if (device->bus)
0123         list_del(&device->list);
0124     if (device->private_free)
0125         device->private_free(device);
0126     kfree(device);
0127     return 0;
0128 }
0129
0130 EXPORT_SYMBOL(snd_i2c_device_free);
0131
0132 int snd_i2c_sendbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
0133 {
0134     return device->bus->ops->sendbytes(device, bytes, count);
0135 }
0136
0137 EXPORT_SYMBOL(snd_i2c_sendbytes);
0138
0139 int snd_i2c_readbytes(struct snd_i2c_device *device, unsigned char *bytes, int count)
0140 {
0141     return device->bus->ops->readbytes(device, bytes, count);
0142 }
0143
0144 EXPORT_SYMBOL(snd_i2c_readbytes);
0145
0146 int snd_i2c_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
0147 {
0148     return bus->ops->probeaddr(bus, addr);
0149 }
0150
0151 EXPORT_SYMBOL(snd_i2c_probeaddr);
0152
0153 /*
0154  *  bit-operations
0155  */
0156
0157 static inline void snd_i2c_bit_hw_start(struct snd_i2c_bus *bus)
0158 {
0159     if (bus->hw_ops.bit->start)
0160         bus->hw_ops.bit->start(bus);
0161 }
0162
0163 static inline void snd_i2c_bit_hw_stop(struct snd_i2c_bus *bus)
0164 {
0165     if (bus->hw_ops.bit->stop)
0166         bus->hw_ops.bit->stop(bus);
0167 }
0168
0169 static void snd_i2c_bit_direction(struct snd_i2c_bus *bus, int clock, int data)
0170 {
0171     if (bus->hw_ops.bit->direction)
0172         bus->hw_ops.bit->direction(bus, clock, data);
0173 }
0174
0175 static void snd_i2c_bit_set(struct snd_i2c_bus *bus, int clock, int data)
0176 {
0177     bus->hw_ops.bit->setlines(bus, clock, data);
0178 }
0179
0180 #if 0
0181 static int snd_i2c_bit_clock(struct snd_i2c_bus *bus)
0182 {
0183     if (bus->hw_ops.bit->getclock)
0184         return bus->hw_ops.bit->getclock(bus);
0185     return -ENXIO;
0186 }
0187 #endif
0188
0189 static int snd_i2c_bit_data(struct snd_i2c_bus *bus, int ack)
0190 {
0191     return bus->hw_ops.bit->getdata(bus, ack);
0192 }
0193
0194 static void snd_i2c_bit_start(struct snd_i2c_bus *bus)
0195 {
0196     snd_i2c_bit_hw_start(bus);
0197     snd_i2c_bit_direction(bus, 1, 1);   /* SCL - wr, SDA - wr */
0198     snd_i2c_bit_set(bus, 1, 1);
0199     snd_i2c_bit_set(bus, 1, 0);
0200     snd_i2c_bit_set(bus, 0, 0);
0201 }
0202
0203 static void snd_i2c_bit_stop(struct snd_i2c_bus *bus)
0204 {
0205     snd_i2c_bit_set(bus, 0, 0);
0206     snd_i2c_bit_set(bus, 1, 0);
0207     snd_i2c_bit_set(bus, 1, 1);
0208     snd_i2c_bit_hw_stop(bus);
0209 }
0210
0211 static void snd_i2c_bit_send(struct snd_i2c_bus *bus, int data)
0212 {
0213     snd_i2c_bit_set(bus, 0, data);
0214     snd_i2c_bit_set(bus, 1, data);
0215     snd_i2c_bit_set(bus, 0, data);
0216 }
0217
0218 static int snd_i2c_bit_ack(struct snd_i2c_bus *bus)
0219 {
0220     int ack;
0221
0222     snd_i2c_bit_set(bus, 0, 1);
0223     snd_i2c_bit_set(bus, 1, 1);
0224     snd_i2c_bit_direction(bus, 1, 0);   /* SCL - wr, SDA - rd */
0225     ack = snd_i2c_bit_data(bus, 1);
0226     snd_i2c_bit_direction(bus, 1, 1);   /* SCL - wr, SDA - wr */
0227     snd_i2c_bit_set(bus, 0, 1);
0228     return ack ? -EIO : 0;
0229 }
0230
0231 static int snd_i2c_bit_sendbyte(struct snd_i2c_bus *bus, unsigned char data)
0232 {
0233     int i, err;
0234
0235     for (i = 7; i >= 0; i--)
0236         snd_i2c_bit_send(bus, !!(data & (1 << i)));
0237     err = snd_i2c_bit_ack(bus);
0238     if (err < 0)
0239         return err;
0240     return 0;
0241 }
0242
0243 static int snd_i2c_bit_readbyte(struct snd_i2c_bus *bus, int last)
0244 {
0245     int i;
0246     unsigned char data = 0;
0247
0248     snd_i2c_bit_set(bus, 0, 1);
0249     snd_i2c_bit_direction(bus, 1, 0);   /* SCL - wr, SDA - rd */
0250     for (i = 7; i >= 0; i--) {
0251         snd_i2c_bit_set(bus, 1, 1);
0252         if (snd_i2c_bit_data(bus, 0))
0253             data |= (1 << i);
0254         snd_i2c_bit_set(bus, 0, 1);
0255     }
0256     snd_i2c_bit_direction(bus, 1, 1);   /* SCL - wr, SDA - wr */
0257     snd_i2c_bit_send(bus, !!last);
0258     return data;
0259 }
0260
0261 static int snd_i2c_bit_sendbytes(struct snd_i2c_device *device,
0262                  unsigned char *bytes, int count)
0263 {
0264     struct snd_i2c_bus *bus = device->bus;
0265     int err, res = 0;
0266
0267     if (device->flags & SND_I2C_DEVICE_ADDRTEN)
0268         return -EIO;        /* not yet implemented */
0269     snd_i2c_bit_start(bus);
0270     err = snd_i2c_bit_sendbyte(bus, device->addr << 1);
0271     if (err < 0) {
0272         snd_i2c_bit_hw_stop(bus);
0273         return err;
0274     }
0275     while (count-- > 0) {
0276         err = snd_i2c_bit_sendbyte(bus, *bytes++);
0277         if (err < 0) {
0278             snd_i2c_bit_hw_stop(bus);
0279             return err;
0280         }
0281         res++;
0282     }
0283     snd_i2c_bit_stop(bus);
0284     return res;
0285 }
0286
0287 static int snd_i2c_bit_readbytes(struct snd_i2c_device *device,
0288                  unsigned char *bytes, int count)
0289 {
0290     struct snd_i2c_bus *bus = device->bus;
0291     int err, res = 0;
0292
0293     if (device->flags & SND_I2C_DEVICE_ADDRTEN)
0294         return -EIO;        /* not yet implemented */
0295     snd_i2c_bit_start(bus);
0296     err = snd_i2c_bit_sendbyte(bus, (device->addr << 1) | 1);
0297     if (err < 0) {
0298         snd_i2c_bit_hw_stop(bus);
0299         return err;
0300     }
0301     while (count-- > 0) {
0302         err = snd_i2c_bit_readbyte(bus, count == 0);
0303         if (err < 0) {
0304             snd_i2c_bit_hw_stop(bus);
0305             return err;
0306         }
0307         *bytes++ = (unsigned char)err;
0308         res++;
0309     }
0310     snd_i2c_bit_stop(bus);
0311     return res;
0312 }
0313
0314 static int snd_i2c_bit_probeaddr(struct snd_i2c_bus *bus, unsigned short addr)
0315 {
0316     int err;
0317
0318     if (addr & 0x8000)  /* 10-bit address */
0319         return -EIO;    /* not yet implemented */
0320     if (addr & 0x7f80)  /* invalid address */
0321         return -EINVAL;
0322     snd_i2c_bit_start(bus);
0323     err = snd_i2c_bit_sendbyte(bus, addr << 1);
0324     snd_i2c_bit_stop(bus);
0325     return err;
0326 }