/*
    Samsung S5H1409 VSB/QAM demodulator driver

    Copyright (C) 2006 Steven Toth <stoth@linuxtv.org>

    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/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/delay.h>
#include <media/dvb_frontend.h>
#include "s5h1409.h"

struct s5h1409_state {

	struct i2c_adapter *i2c;

	/* configuration settings */
	const struct s5h1409_config *config;

	struct dvb_frontend frontend;

	/* previous uncorrected block counter */
	enum fe_modulation current_modulation;

	u32 current_frequency;
	int if_freq;

	u32 is_qam_locked;

	/* QAM tuning state goes through the following state transitions */
#define QAM_STATE_UNTUNED 0
#define QAM_STATE_TUNING_STARTED 1
#define QAM_STATE_INTERLEAVE_SET 2
#define QAM_STATE_QAM_OPTIMIZED_L1 3
#define QAM_STATE_QAM_OPTIMIZED_L2 4
#define QAM_STATE_QAM_OPTIMIZED_L3 5
	u8  qam_state;
};

static int debug;
module_param(debug, int, 0644);
MODULE_PARM_DESC(debug, "Enable verbose debug messages");

#define dprintk	if (debug) printk

/* Register values to initialise the demod, this will set VSB by default */
static struct init_tab {
	u8	reg;
	u16	data;
} init_tab[] = {
	{ 0x00, 0x0071, },
	{ 0x01, 0x3213, },
	{ 0x09, 0x0025, },
	{ 0x1c, 0x001d, },
	{ 0x1f, 0x002d, },
	{ 0x20, 0x001d, },
	{ 0x22, 0x0022, },
	{ 0x23, 0x0020, },
	{ 0x29, 0x110f, },
	{ 0x2a, 0x10b4, },
	{ 0x2b, 0x10ae, },
	{ 0x2c, 0x0031, },
	{ 0x31, 0x010d, },
	{ 0x32, 0x0100, },
	{ 0x44, 0x0510, },
	{ 0x54, 0x0104, },
	{ 0x58, 0x2222, },
	{ 0x59, 0x1162, },
	{ 0x5a, 0x3211, },
	{ 0x5d, 0x0370, },
	{ 0x5e, 0x0296, },
	{ 0x61, 0x0010, },
	{ 0x63, 0x4a00, },
	{ 0x65, 0x0800, },
	{ 0x71, 0x0003, },
	{ 0x72, 0x0470, },
	{ 0x81, 0x0002, },
	{ 0x82, 0x0600, },
	{ 0x86, 0x0002, },
	{ 0x8a, 0x2c38, },
	{ 0x8b, 0x2a37, },
	{ 0x92, 0x302f, },
	{ 0x93, 0x3332, },
	{ 0x96, 0x000c, },
	{ 0x99, 0x0101, },
	{ 0x9c, 0x2e37, },
	{ 0x9d, 0x2c37, },
	{ 0x9e, 0x2c37, },
	{ 0xab, 0x0100, },
	{ 0xac, 0x1003, },
	{ 0xad, 0x103f, },
	{ 0xe2, 0x0100, },
	{ 0xe3, 0x1000, },
	{ 0x28, 0x1010, },
	{ 0xb1, 0x000e, },
};

/* VSB SNR lookup table */
static struct vsb_snr_tab {
	u16	val;
	u16	data;
} vsb_snr_tab[] = {
	{  924, 300, },
	{  923, 300, },
	{  918, 295, },
	{  915, 290, },
	{  911, 285, },
	{  906, 280, },
	{  901, 275, },
	{  896, 270, },
	{  891, 265, },
	{  885, 260, },
	{  879, 255, },
	{  873, 250, },
	{  864, 245, },
	{  858, 240, },
	{  850, 235, },
	{  841, 230, },
	{  832, 225, },
	{  823, 220, },
	{  812, 215, },
	{  802, 210, },
	{  788, 205, },
	{  778, 200, },
	{  767, 195, },
	{  753, 190, },
	{  740, 185, },
	{  725, 180, },
	{  707, 175, },
	{  689, 170, },
	{  671, 165, },
	{  656, 160, },
	{  637, 155, },
	{  616, 150, },
	{  542, 145, },
	{  519, 140, },
	{  507, 135, },
	{  497, 130, },
	{  492, 125, },
	{  474, 120, },
	{  300, 111, },
	{    0,   0, },
};

/* QAM64 SNR lookup table */
static struct qam64_snr_tab {
	u16	val;
	u16	data;
} qam64_snr_tab[] = {
	{    1,   0, },
	{   12, 300, },
	{   15, 290, },
	{   18, 280, },
	{   22, 270, },
	{   23, 268, },
	{   24, 266, },
	{   25, 264, },
	{   27, 262, },
	{   28, 260, },
	{   29, 258, },
	{   30, 256, },
	{   32, 254, },
	{   33, 252, },
	{   34, 250, },
	{   35, 249, },
	{   36, 248, },
	{   37, 247, },
	{   38, 246, },
	{   39, 245, },
	{   40, 244, },
	{   41, 243, },
	{   42, 241, },
	{   43, 240, },
	{   44, 239, },
	{   45, 238, },
	{   46, 237, },
	{   47, 236, },
	{   48, 235, },
	{   49, 234, },
	{   50, 233, },
	{   51, 232, },
	{   52, 231, },
	{   53, 230, },
	{   55, 229, },
	{   56, 228, },
	{   57, 227, },
	{   58, 226, },
	{   59, 225, },
	{   60, 224, },
	{   62, 223, },
	{   63, 222, },
	{   65, 221, },
	{   66, 220, },
	{   68, 219, },
	{   69, 218, },
	{   70, 217, },
	{   72, 216, },
	{   73, 215, },
	{   75, 214, },
	{   76, 213, },
	{   78, 212, },
	{   80, 211, },
	{   81, 210, },
	{   83, 209, },
	{   84, 208, },
	{   85, 207, },
	{   87, 206, },
	{   89, 205, },
	{   91, 204, },
	{   93, 203, },
	{   95, 202, },
	{   96, 201, },
	{  104, 200, },
	{  255,   0, },
};

/* QAM256 SNR lookup table */
static struct qam256_snr_tab {
	u16	val;
	u16	data;
} qam256_snr_tab[] = {
	{    1,   0, },
	{   12, 400, },
	{   13, 390, },
	{   15, 380, },
	{   17, 360, },
	{   19, 350, },
	{   22, 348, },
	{   23, 346, },
	{   24, 344, },
	{   25, 342, },
	{   26, 340, },
	{   27, 336, },
	{   28, 334, },
	{   29, 332, },
	{   30, 330, },
	{   31, 328, },
	{   32, 326, },
	{   33, 325, },
	{   34, 322, },
	{   35, 320, },
	{   37, 318, },
	{   39, 316, },
	{   40, 314, },
	{   41, 312, },
	{   42, 310, },
	{   43, 308, },
	{   46, 306, },
	{   47, 304, },
	{   49, 302, },
	{   51, 300, },
	{   53, 298, },
	{   54, 297, },
	{   55, 296, },
	{   56, 295, },
	{   57, 294, },
	{   59, 293, },
	{   60, 292, },
	{   61, 291, },
	{   63, 290, },
	{   64, 289, },
	{   65, 288, },
	{   66, 287, },
	{   68, 286, },
	{   69, 285, },
	{   71, 284, },
	{   72, 283, },
	{   74, 282, },
	{   75, 281, },
	{   76, 280, },
	{   77, 279, },
	{   78, 278, },
	{   81, 277, },
	{   83, 276, },
	{   84, 275, },
	{   86, 274, },
	{   87, 273, },
	{   89, 272, },
	{   90, 271, },
	{   92, 270, },
	{   93, 269, },
	{   95, 268, },
	{   96, 267, },
	{   98, 266, },
	{  100, 265, },
	{  102, 264, },
	{  104, 263, },
	{  105, 262, },
	{  106, 261, },
	{  110, 260, },
	{  255,   0, },
};

/* 8 bit registers, 16 bit values */
static int s5h1409_writereg(struct s5h1409_state *state, u8 reg, u16 data)
{
	int ret;
	u8 buf[] = { reg, data >> 8,  data & 0xff };

	struct i2c_msg msg = { .addr = state->config->demod_address,
			       .flags = 0, .buf = buf, .len = 3 };

	ret = i2c_transfer(state->i2c, &msg, 1);

	if (ret != 1)
		printk(KERN_ERR "%s: error (reg == 0x%02x, val == 0x%04x, ret == %i)\n",
		       __func__, reg, data, ret);

	return (ret != 1) ? -1 : 0;
}

static u16 s5h1409_readreg(struct s5h1409_state *state, u8 reg)
{
	int ret;
	u8 b0[] = { reg };
	u8 b1[] = { 0, 0 };

	struct i2c_msg msg[] = {
		{ .addr = state->config->demod_address, .flags = 0,
		  .buf = b0, .len = 1 },
		{ .addr = state->config->demod_address, .flags = I2C_M_RD,
		  .buf = b1, .len = 2 } };

	ret = i2c_transfer(state->i2c, msg, 2);

	if (ret != 2)
		printk("%s: readreg error (ret == %i)\n", __func__, ret);
	return (b1[0] << 8) | b1[1];
}

static int s5h1409_softreset(struct dvb_frontend *fe)
{
	struct s5h1409_state *state = fe->demodulator_priv;

	dprintk("%s()\n", __func__);

	s5h1409_writereg(state, 0xf5, 0);
	s5h1409_writereg(state, 0xf5, 1);
	state->is_qam_locked = 0;
	state->qam_state = QAM_STATE_UNTUNED;
	return 0;
}

#define S5H1409_VSB_IF_FREQ 5380
#define S5H1409_QAM_IF_FREQ (state->config->qam_if)

static int s5h1409_set_if_freq(struct dvb_frontend *fe, int KHz)
{
	struct s5h1409_state *state = fe->demodulator_priv;

	dprintk("%s(%d KHz)\n", __func__, KHz);

	switch (KHz) {
	case 4000:
		s5h1409_writereg(state, 0x87, 0x014b);
		s5h1409_writereg(state, 0x88, 0x0cb5);
		s5h1409_writereg(state, 0x89, 0x03e2);
		break;
	case 5380:
	case 44000:
	default:
		s5h1409_writereg(state, 0x87, 0x01be);
		s5h1409_writereg(state, 0x88, 0x0436);
		s5h1409_writereg(state, 0x89, 0x054d);
		break;
	}
	state->if_freq = KHz;

	return 0;
}

static int s5h1409_set_spectralinversion(struct dvb_frontend *fe, int inverted)
{
	struct s5h1409_state *state = fe->demodulator_priv;

	dprintk("%s(%d)\n", __func__, inverted);

	if (inverted == 1)
		return s5h1409_writereg(state, 0x1b, 0x1101); /* Inverted */
	else
		return s5h1409_writereg(state, 0x1b, 0x0110); /* Normal */
}

static int s5h1409_enable_modulation(struct dvb_frontend *fe,
				     enum fe_modulation m)
{
	struct s5h1409_state *state = fe->demodulator_priv;

	dprintk("%s(0x%08x)\n", __func__, m);

	switch (m) {
	case VSB_8:
		dprintk("%s() VSB_8\n", __func__);
		if (state->if_freq != S5H1409_VSB_IF_FREQ)
			s5h1409_set_if_freq(fe, S5H1409_VSB_IF_FREQ);
		s5h1409_writereg(state, 0xf4, 0);
		break;
	case QAM_64:
	case QAM_256:
	case QAM_AUTO:
		dprintk("%s() QAM_AUTO (64/256)\n", __func__);
		if (state->if_freq != S5H1409_QAM_IF_FREQ)
			s5h1409_set_if_freq(fe, S5H1409_QAM_IF_FREQ);
		s5h1409_writereg(state, 0xf4, 1);
		s5h1409_writereg(state, 0x85, 0x110);
		break;
	default:
		dprintk("%s() Invalid modulation\n", __func__);
		return -EINVAL;
	}

	state->current_modulation = m;
	s5h1409_softreset(fe);

	return 0;
}

static int s5h1409_i2c_gate_ctrl(struct dvb_frontend *fe, int enable)
{
	struct s5h1409_state *state = fe->demodulator_priv;

	dprintk("%s(%d)\n", __func__, enable);

	if (enable)
		return s5h1409_writereg(state, 0xf3, 1);
	else
		return s5h1409_writereg(state, 0xf3, 0);
}

static int s5h1409_set_gpio(struct dvb_frontend *fe, int enable)
{
	struct s5h1409_state *state = fe->demodulator_priv;

	dprintk("%s(%d)\n", __func__, enable);

	if (enable)
		return s5h1409_writereg(state, 0xe3,
			s5h1409_readreg(state, 0xe3) | 0x1100);
	else
		return s5h1409_writereg(state, 0xe3,
			s5h1409_readreg(state, 0xe3) & 0xfeff);
}

static int s5h1409_sleep(struct dvb_frontend *fe, int enable)
{
	struct s5h1409_state *state = fe->demodulator_priv;

	dprintk("%s(%d)\n", __func__, enable);

	return s5h1409_writereg(state, 0xf2, enable);
}

static int s5h1409_register_reset(struct dvb_frontend *fe)
{
	struct s5h1409_state *state = fe->demodulator_priv;

	dprintk("%s()\n", __func__);

	return s5h1409_writereg(state, 0xfa, 0);
}

static void s5h1409_set_qam_amhum_mode(struct dvb_frontend *fe)
{
	struct s5h1409_state *state = fe->demodulator_priv;
	u16 reg;

	if (state->qam_state < QAM_STATE_INTERLEAVE_SET) {
		/* We should not perform amhum optimization until
		   the interleave mode has been configured */
		return;
	}

	if (state->qam_state == QAM_STATE_QAM_OPTIMIZED_L3) {
		/* We've already reached the maximum optimization level, so
		   dont bother banging on the status registers */
		return;
	}

	/* QAM EQ lock check */
	reg = s5h1409_readreg(state, 0xf0);

	if ((reg >> 13) & 0x1) {
		reg &= 0xff;

		s5h1409_writereg(state, 0x96, 0x000c);
		if (reg < 0x68) {
			if (state->qam_state < QAM_STATE_QAM_OPTIMIZED_L3) {
				dprintk("%s() setting QAM state to OPT_L3\n",
					__func__);
				s5h1409_writereg(state, 0x93, 0x3130);
				s5h1409_writereg(state, 0x9e, 0x2836);
				state->qam_state = QAM_STATE_QAM_OPTIMIZED_L3;
			}
		} else {
			if (state->qam_state < QAM_STATE_QAM_OPTIMIZED_L2) {
				dprintk("%s() setting QAM state to OPT_L2\n",
					__func__);
				s5h1409_writereg(state, 0x93, 0x3332);
				s5h1409_writereg(state, 0x9e, 0x2c37);
				state->qam_state = QAM_STATE_QAM_OPTIMIZED_L2;
			}
		}

	} else {
		if (state->qam_state < QAM_STATE_QAM_OPTIMIZED_L1) {
			dprintk("%s() setting QAM state to OPT_L1\n", __func__);
			s5h1409_writereg(state, 0x96, 0x0008);
			s5h1409_writereg(state, 0x93, 0x3332);
			s5h1409_writereg(state, 0x9e, 0x2c37);
			state->qam_state = QAM_STATE_QAM_OPTIMIZED_L1;
		}
	}
}

static void s5h1409_set_qam_amhum_mode_legacy(struct dvb_frontend *fe)
{
	struct s5h1409_state *state = fe->demodulator_priv;
	u16 reg;

	if (state->is_qam_locked)
		return;

	/* QAM EQ lock check */
	reg = s5h1409_readreg(state, 0xf0);

	if ((reg >> 13) & 0x1) {

		state->is_qam_locked = 1;
		reg &= 0xff;

		s5h1409_writereg(state, 0x96, 0x00c);
		if ((reg < 0x38) || (reg > 0x68)) {
			s5h1409_writereg(state, 0x93, 0x3332);
			s5h1409_writereg(state, 0x9e, 0x2c37);
		} else {
			s5h1409_writereg(state, 0x93, 0x3130);
			s5h1409_writereg(state, 0x9e, 0x2836);
		}

	} else {
		s5h1409_writereg(state, 0x96, 0x0008);
		s5h1409_writereg(state, 0x93, 0x3332);
		s5h1409_writereg(state, 0x9e, 0x2c37);
	}
}

static void s5h1409_set_qam_interleave_mode(struct dvb_frontend *fe)
{
	struct s5h1409_state *state = fe->demodulator_priv;
	u16 reg, reg1, reg2;

	if (state->qam_state >= QAM_STATE_INTERLEAVE_SET) {
		/* We've done the optimization already */
		return;
	}

	reg = s5h1409_readreg(state, 0xf1);

	/* Master lock */
	if ((reg >> 15) & 0x1) {
		if (state->qam_state == QAM_STATE_UNTUNED ||
		    state->qam_state == QAM_STATE_TUNING_STARTED) {
			dprintk("%s() setting QAM state to INTERLEAVE_SET\n",
				__func__);
			reg1 = s5h1409_readreg(state, 0xb2);
			reg2 = s5h1409_readreg(state, 0xad);

			s5h1409_writereg(state, 0x96, 0x0020);
			s5h1409_writereg(state, 0xad,
				(((reg1 & 0xf000) >> 4) | (reg2 & 0xf0ff)));
			state->qam_state = QAM_STATE_INTERLEAVE_SET;
		}
	} else {
		if (state->qam_state == QAM_STATE_UNTUNED) {
			dprintk("%s() setting QAM state to TUNING_STARTED\n",
				__func__);
			s5h1409_writereg(state, 0x96, 0x08);
			s5h1409_writereg(state, 0xab,
				s5h1409_readreg(state, 0xab) | 0x1001);
			state->qam_state = QAM_STATE_TUNING_STARTED;
		}
	}
}

static void s5h1409_set_qam_interleave_mode_legacy(struct dvb_frontend *fe)
{
	struct s5h1409_state *state = fe->demodulator_priv;
	u16 reg, reg1, reg2;

	reg = s5h1409_readreg(state, 0xf1);

	/* Master lock */
	if ((reg >> 15) & 0x1) {
		if (state->qam_state != 2) {
			state->qam_state = 2;
			reg1 = s5h1409_readreg(state, 0xb2);
			reg2 = s5h1409_readreg(state, 0xad);

			s5h1409_writereg(state, 0x96, 0x20);
			s5h1409_writereg(state, 0xad,
				(((reg1 & 0xf000) >> 4) | (reg2 & 0xf0ff)));
			s5h1409_writereg(state, 0xab,
				s5h1409_readreg(state, 0xab) & 0xeffe);
		}
	} else {
		if (state->qam_state != 1) {
			state->qam_state = 1;
			s5h1409_writereg(state, 0x96, 0x08);
			s5h1409_writereg(state, 0xab,
				s5h1409_readreg(state, 0xab) | 0x1001);
		}
	}
}

/* Talk to the demod, set the FEC, GUARD, QAM settings etc */
static int s5h1409_set_frontend(struct dvb_frontend *fe)
{
	struct dtv_frontend_properties *p = &fe->dtv_property_cache;
	struct s5h1409_state *state = fe->demodulator_priv;

	dprintk("%s(frequency=%d)\n", __func__, p->frequency);

	s5h1409_softreset(fe);

	state->current_frequency = p->frequency;

	s5h1409_enable_modulation(fe, p->modulation);

	if (fe->ops.tuner_ops.set_params) {
		if (fe->ops.i2c_gate_ctrl)
			fe->ops.i2c_gate_ctrl(fe, 1);
		fe->ops.tuner_ops.set_params(fe);
		if (fe->ops.i2c_gate_ctrl)
			fe->ops.i2c_gate_ctrl(fe, 0);
	}

	/* Issue a reset to the demod so it knows to resync against the
	   newly tuned frequency */
	s5h1409_softreset(fe);

	/* Optimize the demod for QAM */
	if (state->current_modulation != VSB_8) {
		/* This almost certainly applies to all boards, but for now
		   only do it for the HVR-1600.  Once the other boards are
		   tested, the "legacy" versions can just go away */
		if (state->config->hvr1600_opt == S5H1409_HVR1600_OPTIMIZE) {
			s5h1409_set_qam_interleave_mode(fe);
			s5h1409_set_qam_amhum_mode(fe);
		} else {
			s5h1409_set_qam_amhum_mode_legacy(fe);
			s5h1409_set_qam_interleave_mode_legacy(fe);
		}
	}

	return 0;
}

static int s5h1409_set_mpeg_timing(struct dvb_frontend *fe, int mode)
{
	struct s5h1409_state *state = fe->demodulator_priv;
	u16 val;

	dprintk("%s(%d)\n", __func__, mode);

	val = s5h1409_readreg(state, 0xac) & 0xcfff;
	switch (mode) {
	case S5H1409_MPEGTIMING_CONTINUOUS_INVERTING_CLOCK:
		val |= 0x0000;
		break;
	case S5H1409_MPEGTIMING_CONTINUOUS_NONINVERTING_CLOCK:
		dprintk("%s(%d) Mode1 or Defaulting\n", __func__, mode);
		val |= 0x1000;
		break;
	case S5H1409_MPEGTIMING_NONCONTINUOUS_INVERTING_CLOCK:
		val |= 0x2000;
		break;
	case S5H1409_MPEGTIMING_NONCONTINUOUS_NONINVERTING_CLOCK:
		val |= 0x3000;
		break;
	default:
		return -EINVAL;
	}

	/* Configure MPEG Signal Timing charactistics */
	return s5h1409_writereg(state, 0xac, val);
}

/* Reset the demod hardware and reset all of the configuration registers
   to a default state. */
static int s5h1409_init(struct dvb_frontend *fe)
{
	int i;

	struct s5h1409_state *state = fe->demodulator_priv;
	dprintk("%s()\n", __func__);

	s5h1409_sleep(fe, 0);
	s5h1409_register_reset(fe);

	for (i = 0; i < ARRAY_SIZE(init_tab); i++)
		s5h1409_writereg(state, init_tab[i].reg, init_tab[i].data);

	/* The datasheet says that after initialisation, VSB is default */
	state->current_modulation = VSB_8;

	/* Optimize for the HVR-1600 if appropriate.  Note that some of these
	   may get folded into the generic case after testing with other
	   devices */
	if (state->config->hvr1600_opt == S5H1409_HVR1600_OPTIMIZE) {
		/* VSB AGC REF */
		s5h1409_writereg(state, 0x09, 0x0050);

		/* Unknown but Windows driver does it... */
		s5h1409_writereg(state, 0x21, 0x0001);
		s5h1409_writereg(state, 0x50, 0x030e);

		/* QAM AGC REF */
		s5h1409_writereg(state, 0x82, 0x0800);
	}

	if (state->config->output_mode == S5H1409_SERIAL_OUTPUT)
		s5h1409_writereg(state, 0xab,
			s5h1409_readreg(state, 0xab) | 0x100); /* Serial */
	else
		s5h1409_writereg(state, 0xab,
			s5h1409_readreg(state, 0xab) & 0xfeff); /* Parallel */

	s5h1409_set_spectralinversion(fe, state->config->inversion);
	s5h1409_set_if_freq(fe, state->if_freq);
	s5h1409_set_gpio(fe, state->config->gpio);
	s5h1409_set_mpeg_timing(fe, state->config->mpeg_timing);
	s5h1409_softreset(fe);

	/* Note: Leaving the I2C gate closed. */
	s5h1409_i2c_gate_ctrl(fe, 0);

	return 0;
}

static int s5h1409_read_status(struct dvb_frontend *fe, enum fe_status *status)
{
	struct s5h1409_state *state = fe->demodulator_priv;
	u16 reg;
	u32 tuner_status = 0;

	*status = 0;

	/* Optimize the demod for QAM */
	if (state->current_modulation != VSB_8) {
		/* This almost certainly applies to all boards, but for now
		   only do it for the HVR-1600.  Once the other boards are
		   tested, the "legacy" versions can just go away */
		if (state->config->hvr1600_opt == S5H1409_HVR1600_OPTIMIZE) {
			s5h1409_set_qam_interleave_mode(fe);
			s5h1409_set_qam_amhum_mode(fe);
		}
	}

	/* Get the demodulator status */
	reg = s5h1409_readreg(state, 0xf1);
	if (reg & 0x1000)
		*status |= FE_HAS_VITERBI;
	if (reg & 0x8000)
		*status |= FE_HAS_LOCK | FE_HAS_SYNC;

	switch (state->config->status_mode) {
	case S5H1409_DEMODLOCKING:
		if (*status & FE_HAS_VITERBI)
			*status |= FE_HAS_CARRIER | FE_HAS_SIGNAL;
		break;
	case S5H1409_TUNERLOCKING:
		/* Get the tuner status */
		if (fe->ops.tuner_ops.get_status) {
			if (fe->ops.i2c_gate_ctrl)
				fe->ops.i2c_gate_ctrl(fe, 1);

			fe->ops.tuner_ops.get_status(fe, &tuner_status);

			if (fe->ops.i2c_gate_ctrl)
				fe->ops.i2c_gate_ctrl(fe, 0);
		}
		if (tuner_status)
			*status |= FE_HAS_CARRIER | FE_HAS_SIGNAL;
		break;
	}

	dprintk("%s() status 0x%08x\n", __func__, *status);

	return 0;
}

static int s5h1409_qam256_lookup_snr(struct dvb_frontend *fe, u16 *snr, u16 v)
{
	int i, ret = -EINVAL;
	dprintk("%s()\n", __func__);

	for (i = 0; i < ARRAY_SIZE(qam256_snr_tab); i++) {
		if (v < qam256_snr_tab[i].val) {
			*snr = qam256_snr_tab[i].data;
			ret = 0;
			break;
		}
	}
	return ret;
}

static int s5h1409_qam64_lookup_snr(struct dvb_frontend *fe, u16 *snr, u16 v)
{
	int i, ret = -EINVAL;
	dprintk("%s()\n", __func__);

	for (i = 0; i < ARRAY_SIZE(qam64_snr_tab); i++) {
		if (v < qam64_snr_tab[i].val) {
			*snr = qam64_snr_tab[i].data;
			ret = 0;
			break;
		}
	}
	return ret;
}

static int s5h1409_vsb_lookup_snr(struct dvb_frontend *fe, u16 *snr, u16 v)
{
	int i, ret = -EINVAL;
	dprintk("%s()\n", __func__);

	for (i = 0; i < ARRAY_SIZE(vsb_snr_tab); i++) {
		if (v > vsb_snr_tab[i].val) {
			*snr = vsb_snr_tab[i].data;
			ret = 0;
			break;
		}
	}
	dprintk("%s() snr=%d\n", __func__, *snr);
	return ret;
}

static int s5h1409_read_snr(struct dvb_frontend *fe, u16 *snr)
{
	struct s5h1409_state *state = fe->demodulator_priv;
	u16 reg;
	dprintk("%s()\n", __func__);

	switch (state->current_modulation) {
	case QAM_64:
		reg = s5h1409_readreg(state, 0xf0) & 0xff;
		return s5h1409_qam64_lookup_snr(fe, snr, reg);
	case QAM_256:
		reg = s5h1409_readreg(state, 0xf0) & 0xff;
		return s5h1409_qam256_lookup_snr(fe, snr, reg);
	case VSB_8:
		reg = s5h1409_readreg(state, 0xf1) & 0x3ff;
		return s5h1409_vsb_lookup_snr(fe, snr, reg);
	default:
		break;
	}

	return -EINVAL;
}

static int s5h1409_read_signal_strength(struct dvb_frontend *fe,
					u16 *signal_strength)
{
	/* borrowed from lgdt330x.c
	 *
	 * Calculate strength from SNR up to 35dB
	 * Even though the SNR can go higher than 35dB,
	 * there is some comfort factor in having a range of
	 * strong signals that can show at 100%
	 */
	u16 snr;
	u32 tmp;
	int ret = s5h1409_read_snr(fe, &snr);

	*signal_strength = 0;

	if (0 == ret) {
		/* The following calculation method was chosen
		 * purely for the sake of code re-use from the
		 * other demod drivers that use this method */

		/* Convert from SNR in dB * 10 to 8.24 fixed-point */
		tmp = (snr * ((1 << 24) / 10));

		/* Convert from 8.24 fixed-point to
		 * scale the range 0 - 35*2^24 into 0 - 65535*/
		if (tmp >= 8960 * 0x10000)
			*signal_strength = 0xffff;
		else
			*signal_strength = tmp / 8960;
	}

	return ret;
}

static int s5h1409_read_ucblocks(struct dvb_frontend *fe, u32 *ucblocks)
{
	struct s5h1409_state *state = fe->demodulator_priv;

	*ucblocks = s5h1409_readreg(state, 0xb5);

	return 0;
}

static int s5h1409_read_ber(struct dvb_frontend *fe, u32 *ber)
{
	return s5h1409_read_ucblocks(fe, ber);
}

static int s5h1409_get_frontend(struct dvb_frontend *fe,
				struct dtv_frontend_properties *p)
{
	struct s5h1409_state *state = fe->demodulator_priv;

	p->frequency = state->current_frequency;
	p->modulation = state->current_modulation;

	return 0;
}

static int s5h1409_get_tune_settings(struct dvb_frontend *fe,
				     struct dvb_frontend_tune_settings *tune)
{
	tune->min_delay_ms = 1000;
	return 0;
}

static void s5h1409_release(struct dvb_frontend *fe)
{
	struct s5h1409_state *state = fe->demodulator_priv;
	kfree(state);
}

static const struct dvb_frontend_ops s5h1409_ops;

struct dvb_frontend *s5h1409_attach(const struct s5h1409_config *config,
				    struct i2c_adapter *i2c)
{
	struct s5h1409_state *state = NULL;
	u16 reg;

	/* allocate memory for the internal state */
	state = kzalloc(sizeof(struct s5h1409_state), GFP_KERNEL);
	if (state == NULL)
		goto error;

	/* setup the state */
	state->config = config;
	state->i2c = i2c;
	state->current_modulation = 0;
	state->if_freq = S5H1409_VSB_IF_FREQ;

	/* check if the demod exists */
	reg = s5h1409_readreg(state, 0x04);
	if ((reg != 0x0066) && (reg != 0x007f))
		goto error;

	/* create dvb_frontend */
	memcpy(&state->frontend.ops, &s5h1409_ops,
	       sizeof(struct dvb_frontend_ops));
	state->frontend.demodulator_priv = state;

	if (s5h1409_init(&state->frontend) != 0) {
		printk(KERN_ERR "%s: Failed to initialize correctly\n",
			__func__);
		goto error;
	}

	/* Note: Leaving the I2C gate open here. */
	s5h1409_i2c_gate_ctrl(&state->frontend, 1);

	return &state->frontend;

error:
	kfree(state);
	return NULL;
}
EXPORT_SYMBOL(s5h1409_attach);

static const struct dvb_frontend_ops s5h1409_ops = {
	.delsys = { SYS_ATSC, SYS_DVBC_ANNEX_B },
	.info = {
		.name			= "Samsung S5H1409 QAM/8VSB Frontend",
		.frequency_min_hz	=  54 * MHz,
		.frequency_max_hz	= 858 * MHz,
		.frequency_stepsize_hz	= 62500,
		.caps = FE_CAN_QAM_64 | FE_CAN_QAM_256 | FE_CAN_8VSB
	},

	.init                 = s5h1409_init,
	.i2c_gate_ctrl        = s5h1409_i2c_gate_ctrl,
	.set_frontend         = s5h1409_set_frontend,
	.get_frontend         = s5h1409_get_frontend,
	.get_tune_settings    = s5h1409_get_tune_settings,
	.read_status          = s5h1409_read_status,
	.read_ber             = s5h1409_read_ber,
	.read_signal_strength = s5h1409_read_signal_strength,
	.read_snr             = s5h1409_read_snr,
	.read_ucblocks        = s5h1409_read_ucblocks,
	.release              = s5h1409_release,
};

MODULE_DESCRIPTION("Samsung S5H1409 QAM-B/ATSC Demodulator driver");
MODULE_AUTHOR("Steven Toth");
MODULE_LICENSE("GPL");