/*
     Driver for Philips tda10086 DVBS Demodulator

     (c) 2006 Andrew de Quincey

     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/init.h>
#include <linux/module.h>
#include <linux/device.h>
#include <linux/jiffies.h>
#include <linux/string.h>
#include <linux/slab.h>

#include "dvb_frontend.h"
#include "tda10086.h"

#define SACLK 96000000

struct tda10086_state {
        struct i2c_adapter* i2c;
        const struct tda10086_config* config;
        struct dvb_frontend frontend;

        /* private demod data */
        u32 frequency;
        u32 symbol_rate;
        bool has_lock;
};

static int debug;
#define dprintk(args...) \
        do { \
                if (debug) printk(KERN_DEBUG "tda10086: " args); \
        } while (0)

static int tda10086_write_byte(struct tda10086_state *state, int reg, int data)
{
        int ret;
        u8 b0[] = { reg, data };
        struct i2c_msg msg = { .flags = 0, .buf = b0, .len = 2 };

        msg.addr = state->config->demod_address;
        ret = i2c_transfer(state->i2c, &msg, 1);

        if (ret != 1)
                dprintk("%s: error reg=0x%x, data=0x%x, ret=%i\n",
                        __func__, reg, data, ret);

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

static int tda10086_read_byte(struct tda10086_state *state, int reg)
{
        int ret;
        u8 b0[] = { reg };
        u8 b1[] = { 0 };
        struct i2c_msg msg[] = {{ .flags = 0, .buf = b0, .len = 1 },
                                { .flags = I2C_M_RD, .buf = b1, .len = 1 }};

        msg[0].addr = state->config->demod_address;
        msg[1].addr = state->config->demod_address;
        ret = i2c_transfer(state->i2c, msg, 2);

        if (ret != 2) {
                dprintk("%s: error reg=0x%x, ret=%i\n", __func__, reg,
                        ret);
                return ret;
        }

        return b1[0];
}

static int tda10086_write_mask(struct tda10086_state *state, int reg, int mask, int data)
{
        int val;

        /* read a byte and check */
        val = tda10086_read_byte(state, reg);
        if (val < 0)
                return val;

        /* mask if off */
        val = val & ~mask;
        val |= data & 0xff;

        /* write it out again */
        return tda10086_write_byte(state, reg, val);
}

static int tda10086_init(struct dvb_frontend* fe)
{
        struct tda10086_state* state = fe->demodulator_priv;
        u8 t22k_off = 0x80;

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

        if (state->config->diseqc_tone)
                t22k_off = 0;
        /* reset */
        tda10086_write_byte(state, 0x00, 0x00);
        msleep(10);

        /* misc setup */
        tda10086_write_byte(state, 0x01, 0x94);
        tda10086_write_byte(state, 0x02, 0x35); /* NOTE: TT drivers appear to disable CSWP */
        tda10086_write_byte(state, 0x03, 0xe4);
        tda10086_write_byte(state, 0x04, 0x43);
        tda10086_write_byte(state, 0x0c, 0x0c);
        tda10086_write_byte(state, 0x1b, 0xb0); /* noise threshold */
        tda10086_write_byte(state, 0x20, 0x89); /* misc */
        tda10086_write_byte(state, 0x30, 0x04); /* acquisition period length */
        tda10086_write_byte(state, 0x32, 0x00); /* irq off */
        tda10086_write_byte(state, 0x31, 0x56); /* setup AFC */

        /* setup PLL (this assumes SACLK = 96MHz) */
        tda10086_write_byte(state, 0x55, 0x2c); /* misc PLL setup */
        if (state->config->xtal_freq == TDA10086_XTAL_16M) {
                tda10086_write_byte(state, 0x3a, 0x0b); /* M=12 */
                tda10086_write_byte(state, 0x3b, 0x01); /* P=2 */
        } else {
                tda10086_write_byte(state, 0x3a, 0x17); /* M=24 */
                tda10086_write_byte(state, 0x3b, 0x00); /* P=1 */
        }
        tda10086_write_mask(state, 0x55, 0x20, 0x00); /* powerup PLL */

        /* setup TS interface */
        tda10086_write_byte(state, 0x11, 0x81);
        tda10086_write_byte(state, 0x12, 0x81);
        tda10086_write_byte(state, 0x19, 0x40); /* parallel mode A + MSBFIRST */
        tda10086_write_byte(state, 0x56, 0x80); /* powerdown WPLL - unused in the mode we use */
        tda10086_write_byte(state, 0x57, 0x08); /* bypass WPLL - unused in the mode we use */
        tda10086_write_byte(state, 0x10, 0x2a);

        /* setup ADC */
        tda10086_write_byte(state, 0x58, 0x61); /* ADC setup */
        tda10086_write_mask(state, 0x58, 0x01, 0x00); /* powerup ADC */

        /* setup AGC */
        tda10086_write_byte(state, 0x05, 0x0B);
        tda10086_write_byte(state, 0x37, 0x63);
        tda10086_write_byte(state, 0x3f, 0x0a); /* NOTE: flydvb varies it */
        tda10086_write_byte(state, 0x40, 0x64);
        tda10086_write_byte(state, 0x41, 0x4f);
        tda10086_write_byte(state, 0x42, 0x43);

        /* setup viterbi */
        tda10086_write_byte(state, 0x1a, 0x11); /* VBER 10^6, DVB, QPSK */

        /* setup carrier recovery */
        tda10086_write_byte(state, 0x3d, 0x80);

        /* setup SEC */
        tda10086_write_byte(state, 0x36, t22k_off); /* all SEC off, 22k tone */
        tda10086_write_byte(state, 0x34, (((1<<19) * (22000/1000)) / (SACLK/1000)));
        tda10086_write_byte(state, 0x35, (((1<<19) * (22000/1000)) / (SACLK/1000)) >> 8);

        return 0;
}

static void tda10086_diseqc_wait(struct tda10086_state *state)
{
        unsigned long timeout = jiffies + msecs_to_jiffies(200);
        while (!(tda10086_read_byte(state, 0x50) & 0x01)) {
                if(time_after(jiffies, timeout)) {
                        printk("%s: diseqc queue not ready, command may be lost.\n", __func__);
                        break;
                }
                msleep(10);
        }
}

static int tda10086_set_tone (struct dvb_frontend* fe, fe_sec_tone_mode_t tone)
{
        struct tda10086_state* state = fe->demodulator_priv;
        u8 t22k_off = 0x80;

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

        if (state->config->diseqc_tone)
                t22k_off = 0;

        switch (tone) {
        case SEC_TONE_OFF:
                tda10086_write_byte(state, 0x36, t22k_off);
                break;

        case SEC_TONE_ON:
                tda10086_write_byte(state, 0x36, 0x01 + t22k_off);
                break;
        }

        return 0;
}

static int tda10086_send_master_cmd (struct dvb_frontend* fe,
                                    struct dvb_diseqc_master_cmd* cmd)
{
        struct tda10086_state* state = fe->demodulator_priv;
        int i;
        u8 oldval;
        u8 t22k_off = 0x80;

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

        if (state->config->diseqc_tone)
                t22k_off = 0;

        if (cmd->msg_len > 6)
                return -EINVAL;
        oldval = tda10086_read_byte(state, 0x36);

        for(i=0; i< cmd->msg_len; i++) {
                tda10086_write_byte(state, 0x48+i, cmd->msg[i]);
        }
        tda10086_write_byte(state, 0x36, (0x08 + t22k_off)
                                        | ((cmd->msg_len - 1) << 4));

        tda10086_diseqc_wait(state);

        tda10086_write_byte(state, 0x36, oldval);

        return 0;
}

static int tda10086_send_burst (struct dvb_frontend* fe, fe_sec_mini_cmd_t minicmd)
{
        struct tda10086_state* state = fe->demodulator_priv;
        u8 oldval = tda10086_read_byte(state, 0x36);
        u8 t22k_off = 0x80;

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

        if (state->config->diseqc_tone)
                t22k_off = 0;

        switch(minicmd) {
        case SEC_MINI_A:
                tda10086_write_byte(state, 0x36, 0x04 + t22k_off);
                break;

        case SEC_MINI_B:
                tda10086_write_byte(state, 0x36, 0x06 + t22k_off);
                break;
        }

        tda10086_diseqc_wait(state);

        tda10086_write_byte(state, 0x36, oldval);

        return 0;
}

static int tda10086_set_inversion(struct tda10086_state *state,
                                  struct dvb_frontend_parameters *fe_params)
{
        u8 invval = 0x80;

        dprintk ("%s %i %i\n", __func__, fe_params->inversion, state->config->invert);

        switch(fe_params->inversion) {
        case INVERSION_OFF:
                if (state->config->invert)
                        invval = 0x40;
                break;
        case INVERSION_ON:
                if (!state->config->invert)
                        invval = 0x40;
                break;
        case INVERSION_AUTO:
                invval = 0x00;
                break;
        }
        tda10086_write_mask(state, 0x0c, 0xc0, invval);

        return 0;
}

static int tda10086_set_symbol_rate(struct tda10086_state *state,
                                    struct dvb_frontend_parameters *fe_params)
{
        u8 dfn = 0;
        u8 afs = 0;
        u8 byp = 0;
        u8 reg37 = 0x43;
        u8 reg42 = 0x43;
        u64 big;
        u32 tmp;
        u32 bdr;
        u32 bdri;
        u32 symbol_rate = fe_params->u.qpsk.symbol_rate;

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

        /* setup the decimation and anti-aliasing filters.. */
        if (symbol_rate < (u32) (SACLK * 0.0137)) {
                dfn=4;
                afs=1;
        } else if (symbol_rate < (u32) (SACLK * 0.0208)) {
                dfn=4;
                afs=0;
        } else if (symbol_rate < (u32) (SACLK * 0.0270)) {
                dfn=3;
                afs=1;
        } else if (symbol_rate < (u32) (SACLK * 0.0416)) {
                dfn=3;
                afs=0;
        } else if (symbol_rate < (u32) (SACLK * 0.0550)) {
                dfn=2;
                afs=1;
        } else if (symbol_rate < (u32) (SACLK * 0.0833)) {
                dfn=2;
                afs=0;
        } else if (symbol_rate < (u32) (SACLK * 0.1100)) {
                dfn=1;
                afs=1;
        } else if (symbol_rate < (u32) (SACLK * 0.1666)) {
                dfn=1;
                afs=0;
        } else if (symbol_rate < (u32) (SACLK * 0.2200)) {
                dfn=0;
                afs=1;
        } else if (symbol_rate < (u32) (SACLK * 0.3333)) {
                dfn=0;
                afs=0;
        } else {
                reg37 = 0x63;
                reg42 = 0x4f;
                byp=1;
        }

        /* calculate BDR */
        big = (1ULL<<21) * ((u64) symbol_rate/1000ULL) * (1ULL<<dfn);
        big += ((SACLK/1000ULL)-1ULL);
        do_div(big, (SACLK/1000ULL));
        bdr = big & 0xfffff;

        /* calculate BDRI */
        tmp = (1<<dfn)*(symbol_rate/1000);
        bdri = ((32 * (SACLK/1000)) + (tmp-1)) / tmp;

        tda10086_write_byte(state, 0x21, (afs << 7) | dfn);
        tda10086_write_mask(state, 0x20, 0x08, byp << 3);
        tda10086_write_byte(state, 0x06, bdr);
        tda10086_write_byte(state, 0x07, bdr >> 8);
        tda10086_write_byte(state, 0x08, bdr >> 16);
        tda10086_write_byte(state, 0x09, bdri);
        tda10086_write_byte(state, 0x37, reg37);
        tda10086_write_byte(state, 0x42, reg42);

        return 0;
}

static int tda10086_set_fec(struct tda10086_state *state,
                            struct dvb_frontend_parameters *fe_params)
{
        u8 fecval;

        dprintk ("%s %i\n", __func__, fe_params->u.qpsk.fec_inner);

        switch(fe_params->u.qpsk.fec_inner) {
        case FEC_1_2:
                fecval = 0x00;
                break;
        case FEC_2_3:
                fecval = 0x01;
                break;
        case FEC_3_4:
                fecval = 0x02;
                break;
        case FEC_4_5:
                fecval = 0x03;
                break;
        case FEC_5_6:
                fecval = 0x04;
                break;
        case FEC_6_7:
                fecval = 0x05;
                break;
        case FEC_7_8:
                fecval = 0x06;
                break;
        case FEC_8_9:
                fecval = 0x07;
                break;
        case FEC_AUTO:
                fecval = 0x08;
                break;
        default:
                return -1;
        }
        tda10086_write_byte(state, 0x0d, fecval);

        return 0;
}

static int tda10086_set_frontend(struct dvb_frontend* fe,
                                 struct dvb_frontend_parameters *fe_params)
{
        struct tda10086_state *state = fe->demodulator_priv;
        int ret;
        u32 freq = 0;
        int freqoff;

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

        /* modify parameters for tuning */
        tda10086_write_byte(state, 0x02, 0x35);
        state->has_lock = false;

        /* set params */
        if (fe->ops.tuner_ops.set_params) {
                fe->ops.tuner_ops.set_params(fe, fe_params);
                if (fe->ops.i2c_gate_ctrl)
                        fe->ops.i2c_gate_ctrl(fe, 0);

                if (fe->ops.tuner_ops.get_frequency)
                        fe->ops.tuner_ops.get_frequency(fe, &freq);
                if (fe->ops.i2c_gate_ctrl)
                        fe->ops.i2c_gate_ctrl(fe, 0);
        }

        /* calcluate the frequency offset (in *Hz* not kHz) */
        freqoff = fe_params->frequency - freq;
        freqoff = ((1<<16) * freqoff) / (SACLK/1000);
        tda10086_write_byte(state, 0x3d, 0x80 | ((freqoff >> 8) & 0x7f));
        tda10086_write_byte(state, 0x3e, freqoff);

        if ((ret = tda10086_set_inversion(state, fe_params)) < 0)
                return ret;
        if ((ret = tda10086_set_symbol_rate(state, fe_params)) < 0)
                return ret;
        if ((ret = tda10086_set_fec(state, fe_params)) < 0)
                return ret;

        /* soft reset + disable TS output until lock */
        tda10086_write_mask(state, 0x10, 0x40, 0x40);
        tda10086_write_mask(state, 0x00, 0x01, 0x00);

        state->symbol_rate = fe_params->u.qpsk.symbol_rate;
        state->frequency = fe_params->frequency;
        return 0;
}

static int tda10086_get_frontend(struct dvb_frontend* fe, struct dvb_frontend_parameters *fe_params)
{
        struct tda10086_state* state = fe->demodulator_priv;
        u8 val;
        int tmp;
        u64 tmp64;

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

        /* check for invalid symbol rate */
        if (fe_params->u.qpsk.symbol_rate < 500000)
                return -EINVAL;

        /* calculate the updated frequency (note: we convert from Hz->kHz) */
        tmp64 = tda10086_read_byte(state, 0x52);
        tmp64 |= (tda10086_read_byte(state, 0x51) << 8);
        if (tmp64 & 0x8000)
                tmp64 |= 0xffffffffffff0000ULL;
        tmp64 = (tmp64 * (SACLK/1000ULL));
        do_div(tmp64, (1ULL<<15) * (1ULL<<1));
        fe_params->frequency = (int) state->frequency + (int) tmp64;

        /* the inversion */
        val = tda10086_read_byte(state, 0x0c);
        if (val & 0x80) {
                switch(val & 0x40) {
                case 0x00:
                        fe_params->inversion = INVERSION_OFF;
                        if (state->config->invert)
                                fe_params->inversion = INVERSION_ON;
                        break;
                default:
                        fe_params->inversion = INVERSION_ON;
                        if (state->config->invert)
                                fe_params->inversion = INVERSION_OFF;
                        break;
                }
        } else {
                tda10086_read_byte(state, 0x0f);
                switch(val & 0x02) {
                case 0x00:
                        fe_params->inversion = INVERSION_OFF;
                        if (state->config->invert)
                                fe_params->inversion = INVERSION_ON;
                        break;
                default:
                        fe_params->inversion = INVERSION_ON;
                        if (state->config->invert)
                                fe_params->inversion = INVERSION_OFF;
                        break;
                }
        }

        /* calculate the updated symbol rate */
        tmp = tda10086_read_byte(state, 0x1d);
        if (tmp & 0x80)
                tmp |= 0xffffff00;
        tmp = (tmp * 480 * (1<<1)) / 128;
        tmp = ((state->symbol_rate/1000) * tmp) / (1000000/1000);
        fe_params->u.qpsk.symbol_rate = state->symbol_rate + tmp;

        /* the FEC */
        val = (tda10086_read_byte(state, 0x0d) & 0x70) >> 4;
        switch(val) {
        case 0x00:
                fe_params->u.qpsk.fec_inner = FEC_1_2;
                break;
        case 0x01:
                fe_params->u.qpsk.fec_inner = FEC_2_3;
                break;
        case 0x02:
                fe_params->u.qpsk.fec_inner = FEC_3_4;
                break;
        case 0x03:
                fe_params->u.qpsk.fec_inner = FEC_4_5;
                break;
        case 0x04:
                fe_params->u.qpsk.fec_inner = FEC_5_6;
                break;
        case 0x05:
                fe_params->u.qpsk.fec_inner = FEC_6_7;
                break;
        case 0x06:
                fe_params->u.qpsk.fec_inner = FEC_7_8;
                break;
        case 0x07:
                fe_params->u.qpsk.fec_inner = FEC_8_9;
                break;
        }

        return 0;
}

static int tda10086_read_status(struct dvb_frontend* fe, fe_status_t *fe_status)
{
        struct tda10086_state* state = fe->demodulator_priv;
        u8 val;

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

        val = tda10086_read_byte(state, 0x0e);
        *fe_status = 0;
        if (val & 0x01)
                *fe_status |= FE_HAS_SIGNAL;
        if (val & 0x02)
                *fe_status |= FE_HAS_CARRIER;
        if (val & 0x04)
                *fe_status |= FE_HAS_VITERBI;
        if (val & 0x08)
                *fe_status |= FE_HAS_SYNC;
        if (val & 0x10) {
                *fe_status |= FE_HAS_LOCK;
                if (!state->has_lock) {
                        state->has_lock = true;
                        /* modify parameters for stable reception */
                        tda10086_write_byte(state, 0x02, 0x00);
                }
        }

        return 0;
}

static int tda10086_read_signal_strength(struct dvb_frontend* fe, u16 * signal)
{
        struct tda10086_state* state = fe->demodulator_priv;
        u8 _str;

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

        _str = 0xff - tda10086_read_byte(state, 0x43);
        *signal = (_str << 8) | _str;

        return 0;
}

static int tda10086_read_snr(struct dvb_frontend* fe, u16 * snr)
{
        struct tda10086_state* state = fe->demodulator_priv;
        u8 _snr;

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

        _snr = 0xff - tda10086_read_byte(state, 0x1c);
        *snr = (_snr << 8) | _snr;

        return 0;
}

static int tda10086_read_ucblocks(struct dvb_frontend* fe, u32* ucblocks)
{
        struct tda10086_state* state = fe->demodulator_priv;

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

        /* read it */
        *ucblocks = tda10086_read_byte(state, 0x18) & 0x7f;

        /* reset counter */
        tda10086_write_byte(state, 0x18, 0x00);
        tda10086_write_byte(state, 0x18, 0x80);

        return 0;
}

static int tda10086_read_ber(struct dvb_frontend* fe, u32* ber)
{
        struct tda10086_state* state = fe->demodulator_priv;

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

        /* read it */
        *ber = 0;
        *ber |= tda10086_read_byte(state, 0x15);
        *ber |= tda10086_read_byte(state, 0x16) << 8;
        *ber |= (tda10086_read_byte(state, 0x17) & 0xf) << 16;

        return 0;
}

static int tda10086_sleep(struct dvb_frontend* fe)
{
        struct tda10086_state* state = fe->demodulator_priv;

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

        tda10086_write_mask(state, 0x00, 0x08, 0x08);

        return 0;
}

static int tda10086_i2c_gate_ctrl(struct dvb_frontend* fe, int enable)
{
        struct tda10086_state* state = fe->demodulator_priv;

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

        if (enable) {
                tda10086_write_mask(state, 0x00, 0x10, 0x10);
        } else {
                tda10086_write_mask(state, 0x00, 0x10, 0x00);
        }

        return 0;
}

static int tda10086_get_tune_settings(struct dvb_frontend* fe, struct dvb_frontend_tune_settings* fesettings)
{
        if (fesettings->parameters.u.qpsk.symbol_rate > 20000000) {
                fesettings->min_delay_ms = 50;
                fesettings->step_size = 2000;
                fesettings->max_drift = 8000;
        } else if (fesettings->parameters.u.qpsk.symbol_rate > 12000000) {
                fesettings->min_delay_ms = 100;
                fesettings->step_size = 1500;
                fesettings->max_drift = 9000;
        } else if (fesettings->parameters.u.qpsk.symbol_rate > 8000000) {
                fesettings->min_delay_ms = 100;
                fesettings->step_size = 1000;
                fesettings->max_drift = 8000;
        } else if (fesettings->parameters.u.qpsk.symbol_rate > 4000000) {
                fesettings->min_delay_ms = 100;
                fesettings->step_size = 500;
                fesettings->max_drift = 7000;
        } else if (fesettings->parameters.u.qpsk.symbol_rate > 2000000) {
                fesettings->min_delay_ms = 200;
                fesettings->step_size = (fesettings->parameters.u.qpsk.symbol_rate / 8000);
                fesettings->max_drift = 14 * fesettings->step_size;
        } else {
                fesettings->min_delay_ms = 200;
                fesettings->step_size = (fesettings->parameters.u.qpsk.symbol_rate / 8000);
                fesettings->max_drift = 18 * fesettings->step_size;
        }

        return 0;
}

static void tda10086_release(struct dvb_frontend* fe)
{
        struct tda10086_state *state = fe->demodulator_priv;
        tda10086_sleep(fe);
        kfree(state);
}

static struct dvb_frontend_ops tda10086_ops = {

        .info = {
                .name     = "Philips TDA10086 DVB-S",
                .type     = FE_QPSK,
                .frequency_min    = 950000,
                .frequency_max    = 2150000,
                .frequency_stepsize = 125,     /* kHz for QPSK frontends */
                .symbol_rate_min  = 1000000,
                .symbol_rate_max  = 45000000,
                .caps = FE_CAN_INVERSION_AUTO |
                        FE_CAN_FEC_1_2 | FE_CAN_FEC_2_3 | FE_CAN_FEC_3_4 |
                        FE_CAN_FEC_5_6 | FE_CAN_FEC_6_7 | FE_CAN_FEC_7_8 | FE_CAN_FEC_AUTO |
                        FE_CAN_QPSK
        },

        .release = tda10086_release,

        .init = tda10086_init,
        .sleep = tda10086_sleep,
        .i2c_gate_ctrl = tda10086_i2c_gate_ctrl,

        .set_frontend = tda10086_set_frontend,
        .get_frontend = tda10086_get_frontend,
        .get_tune_settings = tda10086_get_tune_settings,

        .read_status = tda10086_read_status,
        .read_ber = tda10086_read_ber,
        .read_signal_strength = tda10086_read_signal_strength,
        .read_snr = tda10086_read_snr,
        .read_ucblocks = tda10086_read_ucblocks,

        .diseqc_send_master_cmd = tda10086_send_master_cmd,
        .diseqc_send_burst = tda10086_send_burst,
        .set_tone = tda10086_set_tone,
};

struct dvb_frontend* tda10086_attach(const struct tda10086_config* config,
                                     struct i2c_adapter* i2c)
{
        struct tda10086_state *state;

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

        /* allocate memory for the internal state */
        state = kzalloc(sizeof(struct tda10086_state), GFP_KERNEL);
        if (!state)
                return NULL;

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

        /* check if the demod is there */
        if (tda10086_read_byte(state, 0x1e) != 0xe1) {
                kfree(state);
                return NULL;
        }

        /* create dvb_frontend */
        memcpy(&state->frontend.ops, &tda10086_ops, sizeof(struct dvb_frontend_ops));
        state->frontend.demodulator_priv = state;
        return &state->frontend;
}

module_param(debug, int, 0644);
MODULE_PARM_DESC(debug, "Turn on/off frontend debugging (default:off).");

MODULE_DESCRIPTION("Philips TDA10086 DVB-S Demodulator");
MODULE_AUTHOR("Andrew de Quincey");
MODULE_LICENSE("GPL");

EXPORT_SYMBOL(tda10086_attach);