// SPDX-License-Identifier: GPL-2.0-or-later
/*
    Driver for SAA6588 RDS decoder

    (c) 2005 Hans J. Koch

*/


#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/i2c.h>
#include <linux/types.h>
#include <linux/videodev2.h>
#include <linux/init.h>
#include <linux/errno.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/wait.h>
#include <linux/uaccess.h>

#include <media/i2c/saa6588.h>
#include <media/v4l2-device.h>


/* insmod options */
static unsigned int debug;
static unsigned int xtal;
static unsigned int mmbs;
static unsigned int plvl;
static unsigned int bufblocks = 100;

module_param(debug, int, 0644);
MODULE_PARM_DESC(debug, "enable debug messages");
module_param(xtal, int, 0);
MODULE_PARM_DESC(xtal, "select oscillator frequency (0..3), default 0");
module_param(mmbs, int, 0);
MODULE_PARM_DESC(mmbs, "enable MMBS mode: 0=off (default), 1=on");
module_param(plvl, int, 0);
MODULE_PARM_DESC(plvl, "select pause level (0..3), default 0");
module_param(bufblocks, int, 0);
MODULE_PARM_DESC(bufblocks, "number of buffered blocks, default 100");

MODULE_DESCRIPTION("v4l2 driver module for SAA6588 RDS decoder");
MODULE_AUTHOR("Hans J. Koch <koch@hjk-az.de>");

MODULE_LICENSE("GPL");

/* ---------------------------------------------------------------------- */

#define UNSET       (-1U)

struct saa6588 {
        struct v4l2_subdev sd;
        struct delayed_work work;
        spinlock_t lock;
        unsigned char *buffer;
        unsigned int buf_size;
        unsigned int rd_index;
        unsigned int wr_index;
        unsigned int block_count;
        unsigned char last_blocknum;
        wait_queue_head_t read_queue;
        int data_available_for_read;
        u8 sync;
};

static inline struct saa6588 *to_saa6588(struct v4l2_subdev *sd)
{
        return container_of(sd, struct saa6588, sd);
}

/* ---------------------------------------------------------------------- */

/*
 * SAA6588 defines
 */

/* Initialization and mode control byte (0w) */

/* bit 0+1 (DAC0/DAC1) */
#define cModeStandard           0x00
#define cModeFastPI             0x01
#define cModeReducedRequest     0x02
#define cModeInvalid            0x03

/* bit 2 (RBDS) */
#define cProcessingModeRDS      0x00
#define cProcessingModeRBDS     0x04

/* bit 3+4 (SYM0/SYM1) */
#define cErrCorrectionNone      0x00
#define cErrCorrection2Bits     0x08
#define cErrCorrection5Bits     0x10
#define cErrCorrectionNoneRBDS  0x18

/* bit 5 (NWSY) */
#define cSyncNormal             0x00
#define cSyncRestart            0x20

/* bit 6 (TSQD) */
#define cSigQualityDetectOFF    0x00
#define cSigQualityDetectON     0x40

/* bit 7 (SQCM) */
#define cSigQualityTriggered    0x00
#define cSigQualityContinous    0x80

/* Pause level and flywheel control byte (1w) */

/* bits 0..5 (FEB0..FEB5) */
#define cFlywheelMaxBlocksMask  0x3F
#define cFlywheelDefault        0x20

/* bits 6+7 (PL0/PL1) */
#define cPauseLevel_11mV        0x00
#define cPauseLevel_17mV        0x40
#define cPauseLevel_27mV        0x80
#define cPauseLevel_43mV        0xC0

/* Pause time/oscillator frequency/quality detector control byte (1w) */

/* bits 0..4 (SQS0..SQS4) */
#define cQualityDetectSensMask  0x1F
#define cQualityDetectDefault   0x0F

/* bit 5 (SOSC) */
#define cSelectOscFreqOFF       0x00
#define cSelectOscFreqON        0x20

/* bit 6+7 (PTF0/PTF1) */
#define cOscFreq_4332kHz        0x00
#define cOscFreq_8664kHz        0x40
#define cOscFreq_12996kHz       0x80
#define cOscFreq_17328kHz       0xC0

/* ---------------------------------------------------------------------- */

static bool block_from_buf(struct saa6588 *s, unsigned char *buf)
{
        int i;

        if (s->rd_index == s->wr_index) {
                if (debug > 2)
                        v4l2_info(&s->sd, "Read: buffer empty.\n");
                return false;
        }

        if (debug > 2) {
                v4l2_info(&s->sd, "Read: ");
                for (i = s->rd_index; i < s->rd_index + 3; i++)
                        v4l2_info(&s->sd, "0x%02x ", s->buffer[i]);
        }

        memcpy(buf, &s->buffer[s->rd_index], 3);

        s->rd_index += 3;
        if (s->rd_index >= s->buf_size)
                s->rd_index = 0;
        s->block_count--;

        if (debug > 2)
                v4l2_info(&s->sd, "%d blocks total.\n", s->block_count);

        return true;
}

static void read_from_buf(struct saa6588 *s, struct saa6588_command *a)
{
        unsigned char __user *buf_ptr = a->buffer;
        unsigned char buf[3];
        unsigned long flags;
        unsigned int rd_blocks;
        unsigned int i;

        a->result = 0;
        if (!a->buffer)
                return;

        while (!a->nonblocking && !s->data_available_for_read) {
                int ret = wait_event_interruptible(s->read_queue,
                                             s->data_available_for_read);
                if (ret == -ERESTARTSYS) {
                        a->result = -EINTR;
                        return;
                }
        }

        rd_blocks = a->block_count;
        spin_lock_irqsave(&s->lock, flags);
        if (rd_blocks > s->block_count)
                rd_blocks = s->block_count;
        spin_unlock_irqrestore(&s->lock, flags);

        if (!rd_blocks)
                return;

        for (i = 0; i < rd_blocks; i++) {
                bool got_block;

                spin_lock_irqsave(&s->lock, flags);
                got_block = block_from_buf(s, buf);
                spin_unlock_irqrestore(&s->lock, flags);
                if (!got_block)
                        break;
                if (copy_to_user(buf_ptr, buf, 3)) {
                        a->result = -EFAULT;
                        return;
                }
                buf_ptr += 3;
                a->result += 3;
        }
        spin_lock_irqsave(&s->lock, flags);
        s->data_available_for_read = (s->block_count > 0);
        spin_unlock_irqrestore(&s->lock, flags);
}

static void block_to_buf(struct saa6588 *s, unsigned char *blockbuf)
{
        unsigned int i;

        if (debug > 3)
                v4l2_info(&s->sd, "New block: ");

        for (i = 0; i < 3; ++i) {
                if (debug > 3)
                        v4l2_info(&s->sd, "0x%02x ", blockbuf[i]);
                s->buffer[s->wr_index] = blockbuf[i];
                s->wr_index++;
        }

        if (s->wr_index >= s->buf_size)
                s->wr_index = 0;

        if (s->wr_index == s->rd_index) {
                s->rd_index += 3;
                if (s->rd_index >= s->buf_size)
                        s->rd_index = 0;
        } else
                s->block_count++;

        if (debug > 3)
                v4l2_info(&s->sd, "%d blocks total.\n", s->block_count);
}

static void saa6588_i2c_poll(struct saa6588 *s)
{
        struct i2c_client *client = v4l2_get_subdevdata(&s->sd);
        unsigned long flags;
        unsigned char tmpbuf[6];
        unsigned char blocknum;
        unsigned char tmp;

        /* Although we only need 3 bytes, we have to read at least 6.
           SAA6588 returns garbage otherwise. */
        if (6 != i2c_master_recv(client, &tmpbuf[0], 6)) {
                if (debug > 1)
                        v4l2_info(&s->sd, "read error!\n");
                return;
        }

        s->sync = tmpbuf[0] & 0x10;
        if (!s->sync)
                return;
        blocknum = tmpbuf[0] >> 5;
        if (blocknum == s->last_blocknum) {
                if (debug > 3)
                        v4l2_info(&s->sd, "Saw block %d again.\n", blocknum);
                return;
        }

        s->last_blocknum = blocknum;

        /*
           Byte order according to v4l2 specification:

           Byte 0: Least Significant Byte of RDS Block
           Byte 1: Most Significant Byte of RDS Block
           Byte 2 Bit 7: Error bit. Indicates that an uncorrectable error
           occurred during reception of this block.
           Bit 6: Corrected bit. Indicates that an error was
           corrected for this data block.
           Bits 5-3: Same as bits 0-2.
           Bits 2-0: Block number.

           SAA6588 byte order is Status-MSB-LSB, so we have to swap the
           first and the last of the 3 bytes block.
         */

        swap(tmpbuf[2], tmpbuf[0]);

        /* Map 'Invalid block E' to 'Invalid Block' */
        if (blocknum == 6)
                blocknum = V4L2_RDS_BLOCK_INVALID;
        /* And if are not in mmbs mode, then 'Block E' is also mapped
           to 'Invalid Block'. As far as I can tell MMBS is discontinued,
           and if there is ever a need to support E blocks, then please
           contact the linux-media mailinglist. */
        else if (!mmbs && blocknum == 5)
                blocknum = V4L2_RDS_BLOCK_INVALID;
        tmp = blocknum;
        tmp |= blocknum << 3;   /* Received offset == Offset Name (OK ?) */
        if ((tmpbuf[2] & 0x03) == 0x03)
                tmp |= V4L2_RDS_BLOCK_ERROR;     /* uncorrectable error */
        else if ((tmpbuf[2] & 0x03) != 0x00)
                tmp |= V4L2_RDS_BLOCK_CORRECTED; /* corrected error */
        tmpbuf[2] = tmp;        /* Is this enough ? Should we also check other bits ? */

        spin_lock_irqsave(&s->lock, flags);
        block_to_buf(s, tmpbuf);
        spin_unlock_irqrestore(&s->lock, flags);
        s->data_available_for_read = 1;
        wake_up_interruptible(&s->read_queue);
}

static void saa6588_work(struct work_struct *work)
{
        struct saa6588 *s = container_of(work, struct saa6588, work.work);

        saa6588_i2c_poll(s);
        schedule_delayed_work(&s->work, msecs_to_jiffies(20));
}

static void saa6588_configure(struct saa6588 *s)
{
        struct i2c_client *client = v4l2_get_subdevdata(&s->sd);
        unsigned char buf[3];
        int rc;

        buf[0] = cSyncRestart;
        if (mmbs)
                buf[0] |= cProcessingModeRBDS;

        buf[1] = cFlywheelDefault;
        switch (plvl) {
        case 0:
                buf[1] |= cPauseLevel_11mV;
                break;
        case 1:
                buf[1] |= cPauseLevel_17mV;
                break;
        case 2:
                buf[1] |= cPauseLevel_27mV;
                break;
        case 3:
                buf[1] |= cPauseLevel_43mV;
                break;
        default:                /* nothing */
                break;
        }

        buf[2] = cQualityDetectDefault | cSelectOscFreqON;

        switch (xtal) {
        case 0:
                buf[2] |= cOscFreq_4332kHz;
                break;
        case 1:
                buf[2] |= cOscFreq_8664kHz;
                break;
        case 2:
                buf[2] |= cOscFreq_12996kHz;
                break;
        case 3:
                buf[2] |= cOscFreq_17328kHz;
                break;
        default:                /* nothing */
                break;
        }

        if (debug)
                v4l2_info(&s->sd, "writing: 0w=0x%02x 1w=0x%02x 2w=0x%02x\n",
                          buf[0], buf[1], buf[2]);

        rc = i2c_master_send(client, buf, 3);
        if (rc != 3)
                v4l2_info(&s->sd, "i2c i/o error: rc == %d (should be 3)\n", rc);
}

/* ---------------------------------------------------------------------- */

static long saa6588_command(struct v4l2_subdev *sd, unsigned int cmd, void *arg)
{
        struct saa6588 *s = to_saa6588(sd);
        struct saa6588_command *a = arg;

        switch (cmd) {
                /* --- close() for /dev/radio --- */
        case SAA6588_CMD_CLOSE:
                s->data_available_for_read = 1;
                wake_up_interruptible(&s->read_queue);
                s->data_available_for_read = 0;
                a->result = 0;
                break;
                /* --- read() for /dev/radio --- */
        case SAA6588_CMD_READ:
                read_from_buf(s, a);
                break;
                /* --- poll() for /dev/radio --- */
        case SAA6588_CMD_POLL:
                a->poll_mask = 0;
                if (s->data_available_for_read)
                        a->poll_mask |= EPOLLIN | EPOLLRDNORM;
                poll_wait(a->instance, &s->read_queue, a->event_list);
                break;

        default:
                /* nothing */
                return -ENOIOCTLCMD;
        }
        return 0;
}

static int saa6588_g_tuner(struct v4l2_subdev *sd, struct v4l2_tuner *vt)
{
        struct saa6588 *s = to_saa6588(sd);

        vt->capability |= V4L2_TUNER_CAP_RDS | V4L2_TUNER_CAP_RDS_BLOCK_IO;
        if (s->sync)
                vt->rxsubchans |= V4L2_TUNER_SUB_RDS;
        return 0;
}

static int saa6588_s_tuner(struct v4l2_subdev *sd, const struct v4l2_tuner *vt)
{
        struct saa6588 *s = to_saa6588(sd);

        saa6588_configure(s);
        return 0;
}

/* ----------------------------------------------------------------------- */

static const struct v4l2_subdev_core_ops saa6588_core_ops = {
        .command = saa6588_command,
};

static const struct v4l2_subdev_tuner_ops saa6588_tuner_ops = {
        .g_tuner = saa6588_g_tuner,
        .s_tuner = saa6588_s_tuner,
};

static const struct v4l2_subdev_ops saa6588_ops = {
        .core = &saa6588_core_ops,
        .tuner = &saa6588_tuner_ops,
};

/* ---------------------------------------------------------------------- */

static int saa6588_probe(struct i2c_client *client)
{
        struct saa6588 *s;
        struct v4l2_subdev *sd;

        v4l_info(client, "saa6588 found @ 0x%x (%s)\n",
                        client->addr << 1, client->adapter->name);

        s = devm_kzalloc(&client->dev, sizeof(*s), GFP_KERNEL);
        if (s == NULL)
                return -ENOMEM;

        s->buf_size = bufblocks * 3;

        s->buffer = devm_kzalloc(&client->dev, s->buf_size, GFP_KERNEL);
        if (s->buffer == NULL)
                return -ENOMEM;
        sd = &s->sd;
        v4l2_i2c_subdev_init(sd, client, &saa6588_ops);
        spin_lock_init(&s->lock);
        s->block_count = 0;
        s->wr_index = 0;
        s->rd_index = 0;
        s->last_blocknum = 0xff;
        init_waitqueue_head(&s->read_queue);
        s->data_available_for_read = 0;

        saa6588_configure(s);

        /* start polling via eventd */
        INIT_DELAYED_WORK(&s->work, saa6588_work);
        schedule_delayed_work(&s->work, 0);
        return 0;
}

static void saa6588_remove(struct i2c_client *client)
{
        struct v4l2_subdev *sd = i2c_get_clientdata(client);
        struct saa6588 *s = to_saa6588(sd);

        v4l2_device_unregister_subdev(sd);

        cancel_delayed_work_sync(&s->work);
}

/* ----------------------------------------------------------------------- */

static const struct i2c_device_id saa6588_id[] = {
        { "saa6588" },
        { }
};
MODULE_DEVICE_TABLE(i2c, saa6588_id);

static struct i2c_driver saa6588_driver = {
        .driver = {
                .name   = "saa6588",
        },
        .probe          = saa6588_probe,
        .remove         = saa6588_remove,
        .id_table       = saa6588_id,
};

module_i2c_driver(saa6588_driver);