/* 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/mutex.h>
#include <linux/io.h>		/* outb, outb_p			*/
#include <media/v4l2-ioctl.h>
#include <media/v4l2-device.h>

/*
 * Module info.
 */

MODULE_AUTHOR("Jonas Munsin, Pekka Seppänen <pexu@kapsi.fi>");
MODULE_DESCRIPTION("A driver for the GemTek Radio card.");
MODULE_LICENSE("GPL");
MODULE_VERSION("0.0.4");

/*
 * 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 bool probe	= CONFIG_RADIO_GEMTEK_PROBE;
static bool hardmute;
static bool shutdown	= 1;
static bool keepmuted	= 1;
static bool 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->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);