// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *   Generic i2c interface for ALSA
 *
 *   (c) 1998 Gerd Knorr <kraxel@cs.tu-berlin.de>
 *   Modified for the ALSA driver by Jaroslav Kysela <perex@perex.cz>
 */

#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 <perex@perex.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 const 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 const 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;
        }
        strscpy(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;
        strscpy(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;
}