/*
    Auvitek AU8522 QAM/8VSB demodulator driver

    Copyright (C) 2008 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/delay.h>
#include "dvb_frontend.h"
#include "au8522.h"
#include "au8522_priv.h"

static int debug;

/* Despite the name "hybrid_tuner", the framework works just as well for
   hybrid demodulators as well... */
static LIST_HEAD(hybrid_tuner_instance_list);
static DEFINE_MUTEX(au8522_list_mutex);

#define dprintk(arg...)\
	do { if (debug)\
		printk(arg);\
	} while (0)

/* 16 bit registers, 8 bit values */
int au8522_writereg(struct au8522_state *state, u16 reg, u8 data)
{
	int ret;
	u8 buf[] = { (reg >> 8) | 0x80, reg & 0xff, data };

	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("%s: writereg error (reg == 0x%02x, val == 0x%04x, "
		       "ret == %i)\n", __func__, reg, data, ret);

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

u8 au8522_readreg(struct au8522_state *state, u16 reg)
{
	int ret;
	u8 b0[] = { (reg >> 8) | 0x40, reg & 0xff };
	u8 b1[] = { 0 };

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

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

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

static int au8522_i2c_gate_ctrl(struct dvb_frontend *fe, int enable)
{
	struct au8522_state *state = fe->demodulator_priv;

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

	if (state->operational_mode == AU8522_ANALOG_MODE) {
		/* We're being asked to manage the gate even though we're
		   not in digital mode.  This can occur if we get switched
		   over to analog mode before the dvb_frontend kernel thread
		   has completely shutdown */
		return 0;
	}

	if (enable)
		return au8522_writereg(state, 0x106, 1);
	else
		return au8522_writereg(state, 0x106, 0);
}

struct mse2snr_tab {
	u16 val;
	u16 data;
};

/* VSB SNR lookup table */
static struct mse2snr_tab vsb_mse2snr_tab[] = {
	{   0, 270 },
	{   2, 250 },
	{   3, 240 },
	{   5, 230 },
	{   7, 220 },
	{   9, 210 },
	{  12, 200 },
	{  13, 195 },
	{  15, 190 },
	{  17, 185 },
	{  19, 180 },
	{  21, 175 },
	{  24, 170 },
	{  27, 165 },
	{  31, 160 },
	{  32, 158 },
	{  33, 156 },
	{  36, 152 },
	{  37, 150 },
	{  39, 148 },
	{  40, 146 },
	{  41, 144 },
	{  43, 142 },
	{  44, 140 },
	{  48, 135 },
	{  50, 130 },
	{  43, 142 },
	{  53, 125 },
	{  56, 120 },
	{ 256, 115 },
};

/* QAM64 SNR lookup table */
static struct mse2snr_tab qam64_mse2snr_tab[] = {
	{  15,   0 },
	{  16, 290 },
	{  17, 288 },
	{  18, 286 },
	{  19, 284 },
	{  20, 282 },
	{  21, 281 },
	{  22, 279 },
	{  23, 277 },
	{  24, 275 },
	{  25, 273 },
	{  26, 271 },
	{  27, 269 },
	{  28, 268 },
	{  29, 266 },
	{  30, 264 },
	{  31, 262 },
	{  32, 260 },
	{  33, 259 },
	{  34, 258 },
	{  35, 256 },
	{  36, 255 },
	{  37, 254 },
	{  38, 252 },
	{  39, 251 },
	{  40, 250 },
	{  41, 249 },
	{  42, 248 },
	{  43, 246 },
	{  44, 245 },
	{  45, 244 },
	{  46, 242 },
	{  47, 241 },
	{  48, 240 },
	{  50, 239 },
	{  51, 238 },
	{  53, 237 },
	{  54, 236 },
	{  56, 235 },
	{  57, 234 },
	{  59, 233 },
	{  60, 232 },
	{  62, 231 },
	{  63, 230 },
	{  65, 229 },
	{  67, 228 },
	{  68, 227 },
	{  70, 226 },
	{  71, 225 },
	{  73, 224 },
	{  74, 223 },
	{  76, 222 },
	{  78, 221 },
	{  80, 220 },
	{  82, 219 },
	{  85, 218 },
	{  88, 217 },
	{  90, 216 },
	{  92, 215 },
	{  93, 214 },
	{  94, 212 },
	{  95, 211 },
	{  97, 210 },
	{  99, 209 },
	{ 101, 208 },
	{ 102, 207 },
	{ 104, 206 },
	{ 107, 205 },
	{ 111, 204 },
	{ 114, 203 },
	{ 118, 202 },
	{ 122, 201 },
	{ 125, 200 },
	{ 128, 199 },
	{ 130, 198 },
	{ 132, 197 },
	{ 256, 190 },
};

/* QAM256 SNR lookup table */
static struct mse2snr_tab qam256_mse2snr_tab[] = {
	{  16,   0 },
	{  17, 400 },
	{  18, 398 },
	{  19, 396 },
	{  20, 394 },
	{  21, 392 },
	{  22, 390 },
	{  23, 388 },
	{  24, 386 },
	{  25, 384 },
	{  26, 382 },
	{  27, 380 },
	{  28, 379 },
	{  29, 378 },
	{  30, 377 },
	{  31, 376 },
	{  32, 375 },
	{  33, 374 },
	{  34, 373 },
	{  35, 372 },
	{  36, 371 },
	{  37, 370 },
	{  38, 362 },
	{  39, 354 },
	{  40, 346 },
	{  41, 338 },
	{  42, 330 },
	{  43, 328 },
	{  44, 326 },
	{  45, 324 },
	{  46, 322 },
	{  47, 320 },
	{  48, 319 },
	{  49, 318 },
	{  50, 317 },
	{  51, 316 },
	{  52, 315 },
	{  53, 314 },
	{  54, 313 },
	{  55, 312 },
	{  56, 311 },
	{  57, 310 },
	{  58, 308 },
	{  59, 306 },
	{  60, 304 },
	{  61, 302 },
	{  62, 300 },
	{  63, 298 },
	{  65, 295 },
	{  68, 294 },
	{  70, 293 },
	{  73, 292 },
	{  76, 291 },
	{  78, 290 },
	{  79, 289 },
	{  81, 288 },
	{  82, 287 },
	{  83, 286 },
	{  84, 285 },
	{  85, 284 },
	{  86, 283 },
	{  88, 282 },
	{  89, 281 },
	{ 256, 280 },
};

static int au8522_mse2snr_lookup(struct mse2snr_tab *tab, int sz, int mse,
				 u16 *snr)
{
	int i, ret = -EINVAL;
	dprintk("%s()\n", __func__);

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

static int au8522_set_if(struct dvb_frontend *fe, enum au8522_if_freq if_freq)
{
	struct au8522_state *state = fe->demodulator_priv;
	u8 r0b5, r0b6, r0b7;
	char *ifmhz;

	switch (if_freq) {
	case AU8522_IF_3_25MHZ:
		ifmhz = "3.25";
		r0b5 = 0x00;
		r0b6 = 0x3d;
		r0b7 = 0xa0;
		break;
	case AU8522_IF_4MHZ:
		ifmhz = "4.00";
		r0b5 = 0x00;
		r0b6 = 0x4b;
		r0b7 = 0xd9;
		break;
	case AU8522_IF_6MHZ:
		ifmhz = "6.00";
		r0b5 = 0xfb;
		r0b6 = 0x8e;
		r0b7 = 0x39;
		break;
	default:
		dprintk("%s() IF Frequency not supported\n", __func__);
		return -EINVAL;
	}
	dprintk("%s() %s MHz\n", __func__, ifmhz);
	au8522_writereg(state, 0x80b5, r0b5);
	au8522_writereg(state, 0x80b6, r0b6);
	au8522_writereg(state, 0x80b7, r0b7);

	return 0;
}

/* VSB Modulation table */
static struct {
	u16 reg;
	u16 data;
} VSB_mod_tab[] = {
	{ 0x8090, 0x84 },
	{ 0x4092, 0x11 },
	{ 0x2005, 0x00 },
	{ 0x8091, 0x80 },
	{ 0x80a3, 0x0c },
	{ 0x80a4, 0xe8 },
	{ 0x8081, 0xc4 },
	{ 0x80a5, 0x40 },
	{ 0x80a7, 0x40 },
	{ 0x80a6, 0x67 },
	{ 0x8262, 0x20 },
	{ 0x821c, 0x30 },
	{ 0x80d8, 0x1a },
	{ 0x8227, 0xa0 },
	{ 0x8121, 0xff },
	{ 0x80a8, 0xf0 },
	{ 0x80a9, 0x05 },
	{ 0x80aa, 0x77 },
	{ 0x80ab, 0xf0 },
	{ 0x80ac, 0x05 },
	{ 0x80ad, 0x77 },
	{ 0x80ae, 0x41 },
	{ 0x80af, 0x66 },
	{ 0x821b, 0xcc },
	{ 0x821d, 0x80 },
	{ 0x80a4, 0xe8 },
	{ 0x8231, 0x13 },
};

/* QAM64 Modulation table */
static struct {
	u16 reg;
	u16 data;
} QAM64_mod_tab[] = {
	{ 0x00a3, 0x09 },
	{ 0x00a4, 0x00 },
	{ 0x0081, 0xc4 },
	{ 0x00a5, 0x40 },
	{ 0x00aa, 0x77 },
	{ 0x00ad, 0x77 },
	{ 0x00a6, 0x67 },
	{ 0x0262, 0x20 },
	{ 0x021c, 0x30 },
	{ 0x00b8, 0x3e },
	{ 0x00b9, 0xf0 },
	{ 0x00ba, 0x01 },
	{ 0x00bb, 0x18 },
	{ 0x00bc, 0x50 },
	{ 0x00bd, 0x00 },
	{ 0x00be, 0xea },
	{ 0x00bf, 0xef },
	{ 0x00c0, 0xfc },
	{ 0x00c1, 0xbd },
	{ 0x00c2, 0x1f },
	{ 0x00c3, 0xfc },
	{ 0x00c4, 0xdd },
	{ 0x00c5, 0xaf },
	{ 0x00c6, 0x00 },
	{ 0x00c7, 0x38 },
	{ 0x00c8, 0x30 },
	{ 0x00c9, 0x05 },
	{ 0x00ca, 0x4a },
	{ 0x00cb, 0xd0 },
	{ 0x00cc, 0x01 },
	{ 0x00cd, 0xd9 },
	{ 0x00ce, 0x6f },
	{ 0x00cf, 0xf9 },
	{ 0x00d0, 0x70 },
	{ 0x00d1, 0xdf },
	{ 0x00d2, 0xf7 },
	{ 0x00d3, 0xc2 },
	{ 0x00d4, 0xdf },
	{ 0x00d5, 0x02 },
	{ 0x00d6, 0x9a },
	{ 0x00d7, 0xd0 },
	{ 0x0250, 0x0d },
	{ 0x0251, 0xcd },
	{ 0x0252, 0xe0 },
	{ 0x0253, 0x05 },
	{ 0x0254, 0xa7 },
	{ 0x0255, 0xff },
	{ 0x0256, 0xed },
	{ 0x0257, 0x5b },
	{ 0x0258, 0xae },
	{ 0x0259, 0xe6 },
	{ 0x025a, 0x3d },
	{ 0x025b, 0x0f },
	{ 0x025c, 0x0d },
	{ 0x025d, 0xea },
	{ 0x025e, 0xf2 },
	{ 0x025f, 0x51 },
	{ 0x0260, 0xf5 },
	{ 0x0261, 0x06 },
	{ 0x021a, 0x00 },
	{ 0x0546, 0x40 },
	{ 0x0210, 0xc7 },
	{ 0x0211, 0xaa },
	{ 0x0212, 0xab },
	{ 0x0213, 0x02 },
	{ 0x0502, 0x00 },
	{ 0x0121, 0x04 },
	{ 0x0122, 0x04 },
	{ 0x052e, 0x10 },
	{ 0x00a4, 0xca },
	{ 0x00a7, 0x40 },
	{ 0x0526, 0x01 },
};

/* QAM256 Modulation table */
static struct {
	u16 reg;
	u16 data;
} QAM256_mod_tab[] = {
	{ 0x80a3, 0x09 },
	{ 0x80a4, 0x00 },
	{ 0x8081, 0xc4 },
	{ 0x80a5, 0x40 },
	{ 0x80aa, 0x77 },
	{ 0x80ad, 0x77 },
	{ 0x80a6, 0x67 },
	{ 0x8262, 0x20 },
	{ 0x821c, 0x30 },
	{ 0x80b8, 0x3e },
	{ 0x80b9, 0xf0 },
	{ 0x80ba, 0x01 },
	{ 0x80bb, 0x18 },
	{ 0x80bc, 0x50 },
	{ 0x80bd, 0x00 },
	{ 0x80be, 0xea },
	{ 0x80bf, 0xef },
	{ 0x80c0, 0xfc },
	{ 0x80c1, 0xbd },
	{ 0x80c2, 0x1f },
	{ 0x80c3, 0xfc },
	{ 0x80c4, 0xdd },
	{ 0x80c5, 0xaf },
	{ 0x80c6, 0x00 },
	{ 0x80c7, 0x38 },
	{ 0x80c8, 0x30 },
	{ 0x80c9, 0x05 },
	{ 0x80ca, 0x4a },
	{ 0x80cb, 0xd0 },
	{ 0x80cc, 0x01 },
	{ 0x80cd, 0xd9 },
	{ 0x80ce, 0x6f },
	{ 0x80cf, 0xf9 },
	{ 0x80d0, 0x70 },
	{ 0x80d1, 0xdf },
	{ 0x80d2, 0xf7 },
	{ 0x80d3, 0xc2 },
	{ 0x80d4, 0xdf },
	{ 0x80d5, 0x02 },
	{ 0x80d6, 0x9a },
	{ 0x80d7, 0xd0 },
	{ 0x8250, 0x0d },
	{ 0x8251, 0xcd },
	{ 0x8252, 0xe0 },
	{ 0x8253, 0x05 },
	{ 0x8254, 0xa7 },
	{ 0x8255, 0xff },
	{ 0x8256, 0xed },
	{ 0x8257, 0x5b },
	{ 0x8258, 0xae },
	{ 0x8259, 0xe6 },
	{ 0x825a, 0x3d },
	{ 0x825b, 0x0f },
	{ 0x825c, 0x0d },
	{ 0x825d, 0xea },
	{ 0x825e, 0xf2 },
	{ 0x825f, 0x51 },
	{ 0x8260, 0xf5 },
	{ 0x8261, 0x06 },
	{ 0x821a, 0x00 },
	{ 0x8546, 0x40 },
	{ 0x8210, 0x26 },
	{ 0x8211, 0xf6 },
	{ 0x8212, 0x84 },
	{ 0x8213, 0x02 },
	{ 0x8502, 0x01 },
	{ 0x8121, 0x04 },
	{ 0x8122, 0x04 },
	{ 0x852e, 0x10 },
	{ 0x80a4, 0xca },
	{ 0x80a7, 0x40 },
	{ 0x8526, 0x01 },
};

static int au8522_enable_modulation(struct dvb_frontend *fe,
				    fe_modulation_t m)
{
	struct au8522_state *state = fe->demodulator_priv;
	int i;

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

	switch (m) {
	case VSB_8:
		dprintk("%s() VSB_8\n", __func__);
		for (i = 0; i < ARRAY_SIZE(VSB_mod_tab); i++)
			au8522_writereg(state,
				VSB_mod_tab[i].reg,
				VSB_mod_tab[i].data);
		au8522_set_if(fe, state->config->vsb_if);
		break;
	case QAM_64:
		dprintk("%s() QAM 64\n", __func__);
		for (i = 0; i < ARRAY_SIZE(QAM64_mod_tab); i++)
			au8522_writereg(state,
				QAM64_mod_tab[i].reg,
				QAM64_mod_tab[i].data);
		au8522_set_if(fe, state->config->qam_if);
		break;
	case QAM_256:
		dprintk("%s() QAM 256\n", __func__);
		for (i = 0; i < ARRAY_SIZE(QAM256_mod_tab); i++)
			au8522_writereg(state,
				QAM256_mod_tab[i].reg,
				QAM256_mod_tab[i].data);
		au8522_set_if(fe, state->config->qam_if);
		break;
	default:
		dprintk("%s() Invalid modulation\n", __func__);
		return -EINVAL;
	}

	state->current_modulation = m;

	return 0;
}

/* Talk to the demod, set the FEC, GUARD, QAM settings etc */
static int au8522_set_frontend(struct dvb_frontend *fe)
{
	struct dtv_frontend_properties *c = &fe->dtv_property_cache;
	struct au8522_state *state = fe->demodulator_priv;
	int ret = -EINVAL;

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

	if ((state->current_frequency == c->frequency) &&
	    (state->current_modulation == c->modulation))
		return 0;

	au8522_enable_modulation(fe, c->modulation);

	/* Allow the demod to settle */
	msleep(100);

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

	if (ret < 0)
		return ret;

	state->current_frequency = c->frequency;

	return 0;
}

/* Reset the demod hardware and reset all of the configuration registers
   to a default state. */
int au8522_init(struct dvb_frontend *fe)
{
	struct au8522_state *state = fe->demodulator_priv;
	dprintk("%s()\n", __func__);

	state->operational_mode = AU8522_DIGITAL_MODE;

	/* Clear out any state associated with the digital side of the
	   chip, so that when it gets powered back up it won't think
	   that it is already tuned */
	state->current_frequency = 0;

	au8522_writereg(state, 0xa4, 1 << 5);

	au8522_i2c_gate_ctrl(fe, 1);

	return 0;
}

static int au8522_led_gpio_enable(struct au8522_state *state, int onoff)
{
	struct au8522_led_config *led_config = state->config->led_cfg;
	u8 val;

	/* bail out if we can't control an LED */
	if (!led_config || !led_config->gpio_output ||
	    !led_config->gpio_output_enable || !led_config->gpio_output_disable)
		return 0;

	val = au8522_readreg(state, 0x4000 |
			     (led_config->gpio_output & ~0xc000));
	if (onoff) {
		/* enable GPIO output */
		val &= ~((led_config->gpio_output_enable >> 8) & 0xff);
		val |=  (led_config->gpio_output_enable & 0xff);
	} else {
		/* disable GPIO output */
		val &= ~((led_config->gpio_output_disable >> 8) & 0xff);
		val |=  (led_config->gpio_output_disable & 0xff);
	}
	return au8522_writereg(state, 0x8000 |
			       (led_config->gpio_output & ~0xc000), val);
}

/* led = 0 | off
 * led = 1 | signal ok
 * led = 2 | signal strong
 * led < 0 | only light led if leds are currently off
 */
static int au8522_led_ctrl(struct au8522_state *state, int led)
{
	struct au8522_led_config *led_config = state->config->led_cfg;
	int i, ret = 0;

	/* bail out if we can't control an LED */
	if (!led_config || !led_config->gpio_leds ||
	    !led_config->num_led_states || !led_config->led_states)
		return 0;

	if (led < 0) {
		/* if LED is already lit, then leave it as-is */
		if (state->led_state)
			return 0;
		else
			led *= -1;
	}

	/* toggle LED if changing state */
	if (state->led_state != led) {
		u8 val;

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

		au8522_led_gpio_enable(state, 1);

		val = au8522_readreg(state, 0x4000 |
				     (led_config->gpio_leds & ~0xc000));

		/* start with all leds off */
		for (i = 0; i < led_config->num_led_states; i++)
			val &= ~led_config->led_states[i];

		/* set selected LED state */
		if (led < led_config->num_led_states)
			val |= led_config->led_states[led];
		else if (led_config->num_led_states)
			val |=
			led_config->led_states[led_config->num_led_states - 1];

		ret = au8522_writereg(state, 0x8000 |
				      (led_config->gpio_leds & ~0xc000), val);
		if (ret < 0)
			return ret;

		state->led_state = led;

		if (led == 0)
			au8522_led_gpio_enable(state, 0);
	}

	return 0;
}

int au8522_sleep(struct dvb_frontend *fe)
{
	struct au8522_state *state = fe->demodulator_priv;
	dprintk("%s()\n", __func__);

	/* Only power down if the digital side is currently using the chip */
	if (state->operational_mode == AU8522_ANALOG_MODE) {
		/* We're not in one of the expected power modes, which means
		   that the DVB thread is probably telling us to go to sleep
		   even though the analog frontend has already started using
		   the chip.  So ignore the request */
		return 0;
	}

	/* turn off led */
	au8522_led_ctrl(state, 0);

	/* Power down the chip */
	au8522_writereg(state, 0xa4, 1 << 5);

	state->current_frequency = 0;

	return 0;
}

static int au8522_read_status(struct dvb_frontend *fe, fe_status_t *status)
{
	struct au8522_state *state = fe->demodulator_priv;
	u8 reg;
	u32 tuner_status = 0;

	*status = 0;

	if (state->current_modulation == VSB_8) {
		dprintk("%s() Checking VSB_8\n", __func__);
		reg = au8522_readreg(state, 0x4088);
		if ((reg & 0x03) == 0x03)
			*status |= FE_HAS_LOCK | FE_HAS_SYNC | FE_HAS_VITERBI;
	} else {
		dprintk("%s() Checking QAM\n", __func__);
		reg = au8522_readreg(state, 0x4541);
		if (reg & 0x80)
			*status |= FE_HAS_VITERBI;
		if (reg & 0x20)
			*status |= FE_HAS_LOCK | FE_HAS_SYNC;
	}

	switch (state->config->status_mode) {
	case AU8522_DEMODLOCKING:
		dprintk("%s() DEMODLOCKING\n", __func__);
		if (*status & FE_HAS_VITERBI)
			*status |= FE_HAS_CARRIER | FE_HAS_SIGNAL;
		break;
	case AU8522_TUNERLOCKING:
		/* Get the tuner status */
		dprintk("%s() TUNERLOCKING\n", __func__);
		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;
	}
	state->fe_status = *status;

	if (*status & FE_HAS_LOCK)
		/* turn on LED, if it isn't on already */
		au8522_led_ctrl(state, -1);
	else
		/* turn off LED */
		au8522_led_ctrl(state, 0);

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

	return 0;
}

static int au8522_led_status(struct au8522_state *state, const u16 *snr)
{
	struct au8522_led_config *led_config = state->config->led_cfg;
	int led;
	u16 strong;

	/* bail out if we can't control an LED */
	if (!led_config)
		return 0;

	if (0 == (state->fe_status & FE_HAS_LOCK))
		return au8522_led_ctrl(state, 0);
	else if (state->current_modulation == QAM_256)
		strong = led_config->qam256_strong;
	else if (state->current_modulation == QAM_64)
		strong = led_config->qam64_strong;
	else /* (state->current_modulation == VSB_8) */
		strong = led_config->vsb8_strong;

	if (*snr >= strong)
		led = 2;
	else
		led = 1;

	if ((state->led_state) &&
	    (((strong < *snr) ? (*snr - strong) : (strong - *snr)) <= 10))
		/* snr didn't change enough to bother
		 * changing the color of the led */
		return 0;

	return au8522_led_ctrl(state, led);
}

static int au8522_read_snr(struct dvb_frontend *fe, u16 *snr)
{
	struct au8522_state *state = fe->demodulator_priv;
	int ret = -EINVAL;

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

	if (state->current_modulation == QAM_256)
		ret = au8522_mse2snr_lookup(qam256_mse2snr_tab,
					    ARRAY_SIZE(qam256_mse2snr_tab),
					    au8522_readreg(state, 0x4522),
					    snr);
	else if (state->current_modulation == QAM_64)
		ret = au8522_mse2snr_lookup(qam64_mse2snr_tab,
					    ARRAY_SIZE(qam64_mse2snr_tab),
					    au8522_readreg(state, 0x4522),
					    snr);
	else /* VSB_8 */
		ret = au8522_mse2snr_lookup(vsb_mse2snr_tab,
					    ARRAY_SIZE(vsb_mse2snr_tab),
					    au8522_readreg(state, 0x4311),
					    snr);

	if (state->config->led_cfg)
		au8522_led_status(state, snr);

	return ret;
}

static int au8522_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 = au8522_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 au8522_read_ucblocks(struct dvb_frontend *fe, u32 *ucblocks)
{
	struct au8522_state *state = fe->demodulator_priv;

	if (state->current_modulation == VSB_8)
		*ucblocks = au8522_readreg(state, 0x4087);
	else
		*ucblocks = au8522_readreg(state, 0x4543);

	return 0;
}

static int au8522_read_ber(struct dvb_frontend *fe, u32 *ber)
{
	return au8522_read_ucblocks(fe, ber);
}

static int au8522_get_frontend(struct dvb_frontend *fe,
			       struct dtv_frontend_properties *c)
{
	struct au8522_state *state = fe->demodulator_priv;

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

	return 0;
}

static int au8522_get_tune_settings(struct dvb_frontend *fe,
				    struct dvb_frontend_tune_settings *tune)
{
	tune->min_delay_ms = 1000;
	return 0;
}

static struct dvb_frontend_ops au8522_ops;

int au8522_get_state(struct au8522_state **state, struct i2c_adapter *i2c,
		     u8 client_address)
{
	int ret;

	mutex_lock(&au8522_list_mutex);
	ret = hybrid_tuner_request_state(struct au8522_state, (*state),
					 hybrid_tuner_instance_list,
					 i2c, client_address, "au8522");
	mutex_unlock(&au8522_list_mutex);

	return ret;
}

void au8522_release_state(struct au8522_state *state)
{
	mutex_lock(&au8522_list_mutex);
	if (state != NULL)
		hybrid_tuner_release_state(state);
	mutex_unlock(&au8522_list_mutex);
}


static void au8522_release(struct dvb_frontend *fe)
{
	struct au8522_state *state = fe->demodulator_priv;
	au8522_release_state(state);
}

struct dvb_frontend *au8522_attach(const struct au8522_config *config,
				   struct i2c_adapter *i2c)
{
	struct au8522_state *state = NULL;
	int instance;

	/* allocate memory for the internal state */
	instance = au8522_get_state(&state, i2c, config->demod_address);
	switch (instance) {
	case 0:
		dprintk("%s state allocation failed\n", __func__);
		break;
	case 1:
		/* new demod instance */
		dprintk("%s using new instance\n", __func__);
		break;
	default:
		/* existing demod instance */
		dprintk("%s using existing instance\n", __func__);
		break;
	}

	/* setup the state */
	state->config = config;
	state->i2c = i2c;
	state->operational_mode = AU8522_DIGITAL_MODE;

	/* create dvb_frontend */
	memcpy(&state->frontend.ops, &au8522_ops,
	       sizeof(struct dvb_frontend_ops));
	state->frontend.demodulator_priv = state;

	if (au8522_init(&state->frontend) != 0) {
		printk(KERN_ERR "%s: Failed to initialize correctly\n",
			__func__);
		goto error;
	}

	/* Note: Leaving the I2C gate open here. */
	au8522_i2c_gate_ctrl(&state->frontend, 1);

	return &state->frontend;

error:
	au8522_release_state(state);
	return NULL;
}
EXPORT_SYMBOL(au8522_attach);

static struct dvb_frontend_ops au8522_ops = {
	.delsys = { SYS_ATSC, SYS_DVBC_ANNEX_B },
	.info = {
		.name			= "Auvitek AU8522 QAM/8VSB Frontend",
		.type			= FE_ATSC,
		.frequency_min		= 54000000,
		.frequency_max		= 858000000,
		.frequency_stepsize	= 62500,
		.caps = FE_CAN_QAM_64 | FE_CAN_QAM_256 | FE_CAN_8VSB
	},

	.init                 = au8522_init,
	.sleep                = au8522_sleep,
	.i2c_gate_ctrl        = au8522_i2c_gate_ctrl,
	.set_frontend         = au8522_set_frontend,
	.get_frontend         = au8522_get_frontend,
	.get_tune_settings    = au8522_get_tune_settings,
	.read_status          = au8522_read_status,
	.read_ber             = au8522_read_ber,
	.read_signal_strength = au8522_read_signal_strength,
	.read_snr             = au8522_read_snr,
	.read_ucblocks        = au8522_read_ucblocks,
	.release              = au8522_release,
};

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

MODULE_DESCRIPTION("Auvitek AU8522 QAM-B/ATSC Demodulator driver");
MODULE_AUTHOR("Steven Toth");
MODULE_LICENSE("GPL");