/*
    Driver for SAA6588 RDS decoder

    (c) 2005 Hans J. Koch

    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/


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


#include <media/rds.h>

/* Addresses to scan */
static unsigned short normal_i2c[] = {
        0x20 >> 1,
        0x22 >> 1,
        I2C_CLIENT_END,
};

I2C_CLIENT_INSMOD;

/* insmod options */
static unsigned int debug = 0;
static unsigned int xtal = 0;
static unsigned int rbds = 0;
static unsigned int plvl = 0;
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(rbds, int, 0);
MODULE_PARM_DESC(rbds, "select mode, 0=RDS, 1=RBDS, default 0");
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)
#define PREFIX      "saa6588: "
#define dprintk     if (debug) printk

struct saa6588 {
        struct i2c_client client;
        struct work_struct work;
        struct timer_list timer;
        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;
};

static struct i2c_driver driver;
static struct i2c_client client_template;

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

/*
 * 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 int block_to_user_buf(struct saa6588 *s, unsigned char __user *user_buf)
{
        int i;

        if (s->rd_index == s->wr_index) {
                if (debug > 2)
                        dprintk(PREFIX "Read: buffer empty.\n");
                return 0;
        }

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

        if (copy_to_user(user_buf, &s->buffer[s->rd_index], 3))
                return -EFAULT;

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

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

        return 1;
}

static void read_from_buf(struct saa6588 *s, struct rds_command *a)
{
        unsigned long flags;

        unsigned char __user *buf_ptr = a->buffer;
        unsigned int i;
        unsigned int rd_blocks;

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

        while (!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;
                }
        }

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

        if (!rd_blocks) {
                spin_unlock_irqrestore(&s->lock, flags);
                return;
        }

        for (i = 0; i < rd_blocks; i++) {
                if (block_to_user_buf(s, buf_ptr)) {
                        buf_ptr += 3;
                        a->result++;
                } else
                        break;
        }
        a->result *= 3;
        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)
                dprintk(PREFIX "New block: ");

        for (i = 0; i < 3; ++i) {
                if (debug > 3)
                        dprintk("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)
                dprintk("%d blocks total.\n", s->block_count);
}

static void saa6588_i2c_poll(struct saa6588 *s)
{
        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(&s->client, &tmpbuf[0], 6)) {
                if (debug > 1)
                        dprintk(PREFIX "read error!\n");
                return;
        }

        blocknum = tmpbuf[0] >> 5;
        if (blocknum == s->last_blocknum) {
                if (debug > 3)
                        dprintk("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: Received Offset. Indicates the offset received
           by the sync system.
           Bits 2-0: Offset Name. Indicates the offset applied to this data.

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

        tmp = tmpbuf[2];
        tmpbuf[2] = tmpbuf[0];
        tmpbuf[0] = tmp;

        tmp = blocknum;
        tmp |= blocknum << 3;   /* Received offset == Offset Name (OK ?) */
        if ((tmpbuf[2] & 0x03) == 0x03)
                tmp |= 0x80;    /* uncorrectable error */
        else if ((tmpbuf[2] & 0x03) != 0x00)
                tmp |= 0x40;    /* 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_timer(unsigned long data)
{
        struct saa6588 *s = (struct saa6588 *)data;

        schedule_work(&s->work);
}

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

        saa6588_i2c_poll(s);
        mod_timer(&s->timer, jiffies + msecs_to_jiffies(20));
}

static int saa6588_configure(struct saa6588 *s)
{
        unsigned char buf[3];
        int rc;

        buf[0] = cSyncRestart;
        if (rbds)
                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;
        }

        dprintk(PREFIX "writing: 0w=0x%02x 1w=0x%02x 2w=0x%02x\n",
                buf[0], buf[1], buf[2]);

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

        return 0;
}

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

static int saa6588_attach(struct i2c_adapter *adap, int addr, int kind)
{
        struct saa6588 *s;
        client_template.adapter = adap;
        client_template.addr = addr;

        printk(PREFIX "chip found @ 0x%x\n", addr << 1);

        if (NULL == (s = kmalloc(sizeof(*s), GFP_KERNEL)))
                return -ENOMEM;

        s->buf_size = bufblocks * 3;

        if (NULL == (s->buffer = kmalloc(s->buf_size, GFP_KERNEL))) {
                kfree(s);
                return -ENOMEM;
        }
        spin_lock_init(&s->lock);
        s->client = client_template;
        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;
        i2c_set_clientdata(&s->client, s);
        i2c_attach_client(&s->client);

        saa6588_configure(s);

        /* start polling via eventd */
        INIT_WORK(&s->work, saa6588_work);
        init_timer(&s->timer);
        s->timer.function = saa6588_timer;
        s->timer.data = (unsigned long)s;
        schedule_work(&s->work);
        return 0;
}

static int saa6588_probe(struct i2c_adapter *adap)
{
        if (adap->class & I2C_CLASS_TV_ANALOG)
                return i2c_probe(adap, &addr_data, saa6588_attach);
        return 0;
}

static int saa6588_detach(struct i2c_client *client)
{
        struct saa6588 *s = i2c_get_clientdata(client);

        del_timer_sync(&s->timer);
        flush_scheduled_work();

        i2c_detach_client(client);
        kfree(s->buffer);
        kfree(s);
        return 0;
}

static int saa6588_command(struct i2c_client *client, unsigned int cmd,
                                                        void *arg)
{
        struct saa6588 *s = i2c_get_clientdata(client);
        struct rds_command *a = (struct rds_command *)arg;

        switch (cmd) {
                /* --- open() for /dev/radio --- */
        case RDS_CMD_OPEN:
                a->result = 0;  /* return error if chip doesn't work ??? */
                break;
                /* --- close() for /dev/radio --- */
        case RDS_CMD_CLOSE:
                s->data_available_for_read = 1;
                wake_up_interruptible(&s->read_queue);
                a->result = 0;
                break;
                /* --- read() for /dev/radio --- */
        case RDS_CMD_READ:
                read_from_buf(s, a);
                break;
                /* --- poll() for /dev/radio --- */
        case RDS_CMD_POLL:
                a->result = 0;
                if (s->data_available_for_read) {
                        a->result |= POLLIN | POLLRDNORM;
                }
                poll_wait(a->instance, &s->read_queue, a->event_list);
                break;

        default:
                /* nothing */
                break;
        }
        return 0;
}

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

static struct i2c_driver driver = {
        .driver = {
                .name = "saa6588",
        },
        .id = -1,               /* FIXME */
        .attach_adapter = saa6588_probe,
        .detach_client = saa6588_detach,
        .command = saa6588_command,
};

static struct i2c_client client_template = {
        .name = "saa6588",
        .driver = &driver,
};

static int __init saa6588_init_module(void)
{
        return i2c_add_driver(&driver);
}

static void __exit saa6588_cleanup_module(void)
{
        i2c_del_driver(&driver);
}

module_init(saa6588_init_module);
module_exit(saa6588_cleanup_module);

/*
 * Overrides for Emacs so that we follow Linus's tabbing style.
 * ---------------------------------------------------------------------------
 * Local variables:
 * c-basic-offset: 8
 * End:
 */