/* GemTek radio card driver for Linux (C) 1998 Jonas Munsin <jmunsin@iki.fi>
 *
 * GemTek hasn't released any specs on the card, so the protocol had to
 * be reverse engineered with dosemu.
 *
 * Besides the protocol changes, this is mostly a copy of:
 *
 *    RadioTrack II driver for Linux radio support (C) 1998 Ben Pfaff
 *
 *    Based on RadioTrack I/RadioReveal (C) 1997 M. Kirkwood
 *    Converted to new API by Alan Cox <alan@lxorguk.ukuu.org.uk>
 *    Various bugfixes and enhancements by Russell Kroll <rkroll@exploits.org>
 *
 * TODO: Allow for more than one of these foolish entities :-)
 *
 * Converted to V4L2 API by Mauro Carvalho Chehab <mchehab@infradead.org>
 */

#include <linux/module.h>       /* Modules                      */
#include <linux/init.h>         /* Initdata                     */
#include <linux/ioport.h>       /* request_region               */
#include <linux/delay.h>        /* udelay                       */
#include <linux/videodev2.h>    /* kernel radio structs         */
#include <linux/version.h>      /* for KERNEL_VERSION MACRO     */
#include <linux/mutex.h>
#include <linux/io.h>           /* outb, outb_p                 */
#include <media/v4l2-ioctl.h>
#include <media/v4l2-device.h>

#define RADIO_VERSION KERNEL_VERSION(0, 0, 3)

/*
 * Module info.
 */

MODULE_AUTHOR("Jonas Munsin, Pekka Seppänen <pexu@kapsi.fi>");
MODULE_DESCRIPTION("A driver for the GemTek Radio card.");
MODULE_LICENSE("GPL");

/*
 * Module params.
 */

#ifndef CONFIG_RADIO_GEMTEK_PORT
#define CONFIG_RADIO_GEMTEK_PORT -1
#endif
#ifndef CONFIG_RADIO_GEMTEK_PROBE
#define CONFIG_RADIO_GEMTEK_PROBE 1
#endif

static int io           = CONFIG_RADIO_GEMTEK_PORT;
static int probe        = CONFIG_RADIO_GEMTEK_PROBE;
static int hardmute;
static int shutdown     = 1;
static int keepmuted    = 1;
static int initmute     = 1;
static int radio_nr     = -1;

module_param(io, int, 0444);
MODULE_PARM_DESC(io, "Force I/O port for the GemTek Radio card if automatic "
         "probing is disabled or fails. The most common I/O ports are: 0x20c "
         "0x30c, 0x24c or 0x34c (0x20c, 0x248 and 0x28c have been reported to "
         "work for the combined sound/radiocard).");

module_param(probe, bool, 0444);
MODULE_PARM_DESC(probe, "Enable automatic device probing. Note: only the most "
        "common I/O ports used by the card are probed.");

module_param(hardmute, bool, 0644);
MODULE_PARM_DESC(hardmute, "Enable `hard muting' by shutting down PLL, may "
         "reduce static noise.");

module_param(shutdown, bool, 0644);
MODULE_PARM_DESC(shutdown, "Enable shutting down PLL and muting line when "
         "module is unloaded.");

module_param(keepmuted, bool, 0644);
MODULE_PARM_DESC(keepmuted, "Keep card muted even when frequency is changed.");

module_param(initmute, bool, 0444);
MODULE_PARM_DESC(initmute, "Mute card when module is loaded.");

module_param(radio_nr, int, 0444);

/*
 * Functions for controlling the card.
 */
#define GEMTEK_LOWFREQ  (87*16000)
#define GEMTEK_HIGHFREQ (108*16000)

/*
 * Frequency calculation constants.  Intermediate frequency 10.52 MHz (nominal
 * value 10.7 MHz), reference divisor 6.39 kHz (nominal 6.25 kHz).
 */
#define FSCALE          8
#define IF_OFFSET       ((unsigned int)(10.52 * 16000 * (1<<FSCALE)))
#define REF_FREQ        ((unsigned int)(6.39 * 16 * (1<<FSCALE)))

#define GEMTEK_CK               0x01    /* Clock signal                 */
#define GEMTEK_DA               0x02    /* Serial data                  */
#define GEMTEK_CE               0x04    /* Chip enable                  */
#define GEMTEK_NS               0x08    /* No signal                    */
#define GEMTEK_MT               0x10    /* Line mute                    */
#define GEMTEK_STDF_3_125_KHZ   0x01    /* Standard frequency 3.125 kHz */
#define GEMTEK_PLL_OFF          0x07    /* PLL off                      */

#define BU2614_BUS_SIZE 32      /* BU2614 / BU2614FS bus size           */

#define SHORT_DELAY 5           /* usec */
#define LONG_DELAY 75           /* usec */

struct gemtek {
        struct v4l2_device v4l2_dev;
        struct video_device vdev;
        struct mutex lock;
        unsigned long lastfreq;
        int muted;
        int verified;
        int io;
        u32 bu2614data;
};

static struct gemtek gemtek_card;

#define BU2614_FREQ_BITS        16 /* D0..D15, Frequency data           */
#define BU2614_PORT_BITS        3 /* P0..P2, Output port control data   */
#define BU2614_VOID_BITS        4 /* unused                             */
#define BU2614_FMES_BITS        1 /* CT, Frequency measurement beginning data */
#define BU2614_STDF_BITS        3 /* R0..R2, Standard frequency data    */
#define BU2614_SWIN_BITS        1 /* S, Switch between FMIN / AMIN      */
#define BU2614_SWAL_BITS        1 /* PS, Swallow counter division (AMIN only)*/
#define BU2614_VOID2_BITS       1 /* unused                             */
#define BU2614_FMUN_BITS        1 /* GT, Frequency measurement time & unlock */
#define BU2614_TEST_BITS        1 /* TS, Test data is input             */

#define BU2614_FREQ_SHIFT       0
#define BU2614_PORT_SHIFT       (BU2614_FREQ_BITS + BU2614_FREQ_SHIFT)
#define BU2614_VOID_SHIFT       (BU2614_PORT_BITS + BU2614_PORT_SHIFT)
#define BU2614_FMES_SHIFT       (BU2614_VOID_BITS + BU2614_VOID_SHIFT)
#define BU2614_STDF_SHIFT       (BU2614_FMES_BITS + BU2614_FMES_SHIFT)
#define BU2614_SWIN_SHIFT       (BU2614_STDF_BITS + BU2614_STDF_SHIFT)
#define BU2614_SWAL_SHIFT       (BU2614_SWIN_BITS + BU2614_SWIN_SHIFT)
#define BU2614_VOID2_SHIFT      (BU2614_SWAL_BITS + BU2614_SWAL_SHIFT)
#define BU2614_FMUN_SHIFT       (BU2614_VOID2_BITS + BU2614_VOID2_SHIFT)
#define BU2614_TEST_SHIFT       (BU2614_FMUN_BITS + BU2614_FMUN_SHIFT)

#define MKMASK(field)   (((1<<BU2614_##field##_BITS) - 1) << \
                        BU2614_##field##_SHIFT)
#define BU2614_PORT_MASK        MKMASK(PORT)
#define BU2614_FREQ_MASK        MKMASK(FREQ)
#define BU2614_VOID_MASK        MKMASK(VOID)
#define BU2614_FMES_MASK        MKMASK(FMES)
#define BU2614_STDF_MASK        MKMASK(STDF)
#define BU2614_SWIN_MASK        MKMASK(SWIN)
#define BU2614_SWAL_MASK        MKMASK(SWAL)
#define BU2614_VOID2_MASK       MKMASK(VOID2)
#define BU2614_FMUN_MASK        MKMASK(FMUN)
#define BU2614_TEST_MASK        MKMASK(TEST)

/*
 * Set data which will be sent to BU2614FS.
 */
#define gemtek_bu2614_set(dev, field, data) ((dev)->bu2614data = \
        ((dev)->bu2614data & ~field##_MASK) | ((data) << field##_SHIFT))

/*
 * Transmit settings to BU2614FS over GemTek IC.
 */
static void gemtek_bu2614_transmit(struct gemtek *gt)
{
        int i, bit, q, mute;

        mutex_lock(&gt->lock);

        mute = gt->muted ? GEMTEK_MT : 0x00;

        outb_p(mute | GEMTEK_DA | GEMTEK_CK, gt->io);
        udelay(SHORT_DELAY);
        outb_p(mute | GEMTEK_CE | GEMTEK_DA | GEMTEK_CK, gt->io);
        udelay(LONG_DELAY);

        for (i = 0, q = gt->bu2614data; i < 32; i++, q >>= 1) {
                bit = (q & 1) ? GEMTEK_DA : 0;
                outb_p(mute | GEMTEK_CE | bit, gt->io);
                udelay(SHORT_DELAY);
                outb_p(mute | GEMTEK_CE | bit | GEMTEK_CK, gt->io);
                udelay(SHORT_DELAY);
        }

        outb_p(mute | GEMTEK_DA | GEMTEK_CK, gt->io);
        udelay(SHORT_DELAY);
        outb_p(mute | GEMTEK_CE | GEMTEK_DA | GEMTEK_CK, gt->io);
        udelay(LONG_DELAY);

        mutex_unlock(&gt->lock);
}

/*
 * Calculate divisor from FM-frequency for BU2614FS (3.125 KHz STDF expected).
 */
static unsigned long gemtek_convfreq(unsigned long freq)
{
        return ((freq<<FSCALE) + IF_OFFSET + REF_FREQ/2) / REF_FREQ;
}

/*
 * Set FM-frequency.
 */
static void gemtek_setfreq(struct gemtek *gt, unsigned long freq)
{
        if (keepmuted && hardmute && gt->muted)
                return;

        freq = clamp_val(freq, GEMTEK_LOWFREQ, GEMTEK_HIGHFREQ);

        gt->lastfreq = freq;
        gt->muted = 0;

        gemtek_bu2614_set(gt, BU2614_PORT, 0);
        gemtek_bu2614_set(gt, BU2614_FMES, 0);
        gemtek_bu2614_set(gt, BU2614_SWIN, 0);  /* FM-mode      */
        gemtek_bu2614_set(gt, BU2614_SWAL, 0);
        gemtek_bu2614_set(gt, BU2614_FMUN, 1);  /* GT bit set   */
        gemtek_bu2614_set(gt, BU2614_TEST, 0);

        gemtek_bu2614_set(gt, BU2614_STDF, GEMTEK_STDF_3_125_KHZ);
        gemtek_bu2614_set(gt, BU2614_FREQ, gemtek_convfreq(freq));

        gemtek_bu2614_transmit(gt);
}

/*
 * Set mute flag.
 */
static void gemtek_mute(struct gemtek *gt)
{
        int i;

        gt->muted = 1;

        if (hardmute) {
                /* Turn off PLL, disable data output */
                gemtek_bu2614_set(gt, BU2614_PORT, 0);
                gemtek_bu2614_set(gt, BU2614_FMES, 0);  /* CT bit off   */
                gemtek_bu2614_set(gt, BU2614_SWIN, 0);  /* FM-mode      */
                gemtek_bu2614_set(gt, BU2614_SWAL, 0);
                gemtek_bu2614_set(gt, BU2614_FMUN, 0);  /* GT bit off   */
                gemtek_bu2614_set(gt, BU2614_TEST, 0);
                gemtek_bu2614_set(gt, BU2614_STDF, GEMTEK_PLL_OFF);
                gemtek_bu2614_set(gt, BU2614_FREQ, 0);
                gemtek_bu2614_transmit(gt);
                return;
        }

        mutex_lock(&gt->lock);

        /* Read bus contents (CE, CK and DA). */
        i = inb_p(gt->io);
        /* Write it back with mute flag set. */
        outb_p((i >> 5) | GEMTEK_MT, gt->io);
        udelay(SHORT_DELAY);

        mutex_unlock(&gt->lock);
}

/*
 * Unset mute flag.
 */
static void gemtek_unmute(struct gemtek *gt)
{
        int i;

        gt->muted = 0;
        if (hardmute) {
                /* Turn PLL back on. */
                gemtek_setfreq(gt, gt->lastfreq);
                return;
        }
        mutex_lock(&gt->lock);

        i = inb_p(gt->io);
        outb_p(i >> 5, gt->io);
        udelay(SHORT_DELAY);

        mutex_unlock(&gt->lock);
}

/*
 * Get signal strength (= stereo status).
 */
static inline int gemtek_getsigstr(struct gemtek *gt)
{
        int sig;

        mutex_lock(&gt->lock);
        sig = inb_p(gt->io) & GEMTEK_NS ? 0 : 1;
        mutex_unlock(&gt->lock);
        return sig;
}

/*
 * Check if requested card acts like GemTek Radio card.
 */
static int gemtek_verify(struct gemtek *gt, int port)
{
        int i, q;

        if (gt->verified == port)
                return 1;

        mutex_lock(&gt->lock);

        q = inb_p(port);        /* Read bus contents before probing. */
        /* Try to turn on CE, CK and DA respectively and check if card responds
           properly. */
        for (i = 0; i < 3; ++i) {
                outb_p(1 << i, port);
                udelay(SHORT_DELAY);

                if ((inb_p(port) & (~GEMTEK_NS)) != (0x17 | (1 << (i + 5)))) {
                        mutex_unlock(&gt->lock);
                        return 0;
                }
        }
        outb_p(q >> 5, port);   /* Write bus contents back. */
        udelay(SHORT_DELAY);

        mutex_unlock(&gt->lock);
        gt->verified = port;

        return 1;
}

/*
 * Automatic probing for card.
 */
static int gemtek_probe(struct gemtek *gt)
{
        struct v4l2_device *v4l2_dev = &gt->v4l2_dev;
        int ioports[] = { 0x20c, 0x30c, 0x24c, 0x34c, 0x248, 0x28c };
        int i;

        if (!probe) {
                v4l2_info(v4l2_dev, "Automatic device probing disabled.\n");
                return -1;
        }

        v4l2_info(v4l2_dev, "Automatic device probing enabled.\n");

        for (i = 0; i < ARRAY_SIZE(ioports); ++i) {
                v4l2_info(v4l2_dev, "Trying I/O port 0x%x...\n", ioports[i]);

                if (!request_region(ioports[i], 1, "gemtek-probe")) {
                        v4l2_warn(v4l2_dev, "I/O port 0x%x busy!\n",
                               ioports[i]);
                        continue;
                }

                if (gemtek_verify(gt, ioports[i])) {
                        v4l2_info(v4l2_dev, "Card found from I/O port "
                               "0x%x!\n", ioports[i]);

                        release_region(ioports[i], 1);
                        gt->io = ioports[i];
                        return gt->io;
                }

                release_region(ioports[i], 1);
        }

        v4l2_err(v4l2_dev, "Automatic probing failed!\n");
        return -1;
}

/*
 * Video 4 Linux stuff.
 */

static const struct v4l2_file_operations gemtek_fops = {
        .owner          = THIS_MODULE,
        .unlocked_ioctl = video_ioctl2,
};

static int vidioc_querycap(struct file *file, void *priv,
                           struct v4l2_capability *v)
{
        strlcpy(v->driver, "radio-gemtek", sizeof(v->driver));
        strlcpy(v->card, "GemTek", sizeof(v->card));
        strlcpy(v->bus_info, "ISA", sizeof(v->bus_info));
        v->version = RADIO_VERSION;
        v->capabilities = V4L2_CAP_TUNER | V4L2_CAP_RADIO;
        return 0;
}

static int vidioc_g_tuner(struct file *file, void *priv, struct v4l2_tuner *v)
{
        struct gemtek *gt = video_drvdata(file);

        if (v->index > 0)
                return -EINVAL;

        strlcpy(v->name, "FM", sizeof(v->name));
        v->type = V4L2_TUNER_RADIO;
        v->rangelow = GEMTEK_LOWFREQ;
        v->rangehigh = GEMTEK_HIGHFREQ;
        v->capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_STEREO;
        v->signal = 0xffff * gemtek_getsigstr(gt);
        if (v->signal) {
                v->audmode = V4L2_TUNER_MODE_STEREO;
                v->rxsubchans = V4L2_TUNER_SUB_STEREO;
        } else {
                v->audmode = V4L2_TUNER_MODE_MONO;
                v->rxsubchans = V4L2_TUNER_SUB_MONO;
        }
        return 0;
}

static int vidioc_s_tuner(struct file *file, void *priv, struct v4l2_tuner *v)
{
        return (v->index != 0) ? -EINVAL : 0;
}

static int vidioc_g_frequency(struct file *file, void *priv,
                              struct v4l2_frequency *f)
{
        struct gemtek *gt = video_drvdata(file);

        if (f->tuner != 0)
                return -EINVAL;
        f->type = V4L2_TUNER_RADIO;
        f->frequency = gt->lastfreq;
        return 0;
}

static int vidioc_s_frequency(struct file *file, void *priv,
                              struct v4l2_frequency *f)
{
        struct gemtek *gt = video_drvdata(file);

        if (f->tuner != 0 || f->type != V4L2_TUNER_RADIO)
                return -EINVAL;
        gemtek_setfreq(gt, f->frequency);
        return 0;
}

static int vidioc_queryctrl(struct file *file, void *priv,
                            struct v4l2_queryctrl *qc)
{
        switch (qc->id) {
        case V4L2_CID_AUDIO_MUTE:
                return v4l2_ctrl_query_fill(qc, 0, 1, 1, 0);
        default:
                return -EINVAL;
        }
}

static int vidioc_g_ctrl(struct file *file, void *priv,
                         struct v4l2_control *ctrl)
{
        struct gemtek *gt = video_drvdata(file);

        switch (ctrl->id) {
        case V4L2_CID_AUDIO_MUTE:
                ctrl->value = gt->muted;
                return 0;
        }
        return -EINVAL;
}

static int vidioc_s_ctrl(struct file *file, void *priv,
                         struct v4l2_control *ctrl)
{
        struct gemtek *gt = video_drvdata(file);

        switch (ctrl->id) {
        case V4L2_CID_AUDIO_MUTE:
                if (ctrl->value)
                        gemtek_mute(gt);
                else
                        gemtek_unmute(gt);
                return 0;
        }
        return -EINVAL;
}

static int vidioc_g_input(struct file *filp, void *priv, unsigned int *i)
{
        *i = 0;
        return 0;
}

static int vidioc_s_input(struct file *filp, void *priv, unsigned int i)
{
        return (i != 0) ? -EINVAL : 0;
}

static int vidioc_g_audio(struct file *file, void *priv, struct v4l2_audio *a)
{
        a->index = 0;
        strlcpy(a->name, "Radio", sizeof(a->name));
        a->capability = V4L2_AUDCAP_STEREO;
        return 0;
}

static int vidioc_s_audio(struct file *file, void *priv, struct v4l2_audio *a)
{
        return (a->index != 0) ? -EINVAL : 0;
}

static const struct v4l2_ioctl_ops gemtek_ioctl_ops = {
        .vidioc_querycap        = vidioc_querycap,
        .vidioc_g_tuner         = vidioc_g_tuner,
        .vidioc_s_tuner         = vidioc_s_tuner,
        .vidioc_g_audio         = vidioc_g_audio,
        .vidioc_s_audio         = vidioc_s_audio,
        .vidioc_g_input         = vidioc_g_input,
        .vidioc_s_input         = vidioc_s_input,
        .vidioc_g_frequency     = vidioc_g_frequency,
        .vidioc_s_frequency     = vidioc_s_frequency,
        .vidioc_queryctrl       = vidioc_queryctrl,
        .vidioc_g_ctrl          = vidioc_g_ctrl,
        .vidioc_s_ctrl          = vidioc_s_ctrl
};

/*
 * Initialization / cleanup related stuff.
 */

static int __init gemtek_init(void)
{
        struct gemtek *gt = &gemtek_card;
        struct v4l2_device *v4l2_dev = &gt->v4l2_dev;
        int res;

        strlcpy(v4l2_dev->name, "gemtek", sizeof(v4l2_dev->name));

        v4l2_info(v4l2_dev, "GemTek Radio card driver: v0.0.3\n");

        mutex_init(&gt->lock);

        gt->verified = -1;
        gt->io = io;
        gemtek_probe(gt);
        if (gt->io) {
                if (!request_region(gt->io, 1, "gemtek")) {
                        v4l2_err(v4l2_dev, "I/O port 0x%x already in use.\n", gt->io);
                        return -EBUSY;
                }

                if (!gemtek_verify(gt, gt->io))
                        v4l2_warn(v4l2_dev, "Card at I/O port 0x%x does not "
                               "respond properly, check your "
                               "configuration.\n", gt->io);
                else
                        v4l2_info(v4l2_dev, "Using I/O port 0x%x.\n", gt->io);
        } else if (probe) {
                v4l2_err(v4l2_dev, "Automatic probing failed and no "
                       "fixed I/O port defined.\n");
                return -ENODEV;
        } else {
                v4l2_err(v4l2_dev, "Automatic probing disabled but no fixed "
                       "I/O port defined.");
                return -EINVAL;
        }

        res = v4l2_device_register(NULL, v4l2_dev);
        if (res < 0) {
                v4l2_err(v4l2_dev, "Could not register v4l2_device\n");
                release_region(gt->io, 1);
                return res;
        }

        strlcpy(gt->vdev.name, v4l2_dev->name, sizeof(gt->vdev.name));
        gt->vdev.v4l2_dev = v4l2_dev;
        gt->vdev.fops = &gemtek_fops;
        gt->vdev.ioctl_ops = &gemtek_ioctl_ops;
        gt->vdev.release = video_device_release_empty;
        video_set_drvdata(&gt->vdev, gt);

        /* Set defaults */
        gt->lastfreq = GEMTEK_LOWFREQ;
        gt->bu2614data = 0;

        if (initmute)
                gemtek_mute(gt);

        if (video_register_device(&gt->vdev, VFL_TYPE_RADIO, radio_nr) < 0) {
                v4l2_device_unregister(v4l2_dev);
                release_region(gt->io, 1);
                return -EBUSY;
        }

        return 0;
}

/*
 * Module cleanup
 */
static void __exit gemtek_exit(void)
{
        struct gemtek *gt = &gemtek_card;
        struct v4l2_device *v4l2_dev = &gt->v4l2_dev;

        if (shutdown) {
                hardmute = 1;   /* Turn off PLL */
                gemtek_mute(gt);
        } else {
                v4l2_info(v4l2_dev, "Module unloaded but card not muted!\n");
        }

        video_unregister_device(&gt->vdev);
        v4l2_device_unregister(&gt->v4l2_dev);
        release_region(gt->io, 1);
}

module_init(gemtek_init);
module_exit(gemtek_exit);