// SPDX-License-Identifier: GPL-2.0
/*
 * This file is the ADC part of the STM32 DFSDM driver
 *
 * Copyright (C) 2017, STMicroelectronics - All Rights Reserved
 * Author: Arnaud Pouliquen <arnaud.pouliquen@st.com>.
 */

#include <linux/dmaengine.h>
#include <linux/dma-mapping.h>
#include <linux/iio/adc/stm32-dfsdm-adc.h>
#include <linux/iio/buffer.h>
#include <linux/iio/hw-consumer.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/timer/stm32-lptim-trigger.h>
#include <linux/iio/timer/stm32-timer-trigger.h>
#include <linux/iio/trigger.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/interrupt.h>
#include <linux/module.h>
#include <linux/of_device.h>
#include <linux/platform_device.h>
#include <linux/regmap.h>
#include <linux/slab.h>

#include "stm32-dfsdm.h"

#define DFSDM_DMA_BUFFER_SIZE (4 * PAGE_SIZE)

/* Conversion timeout */
#define DFSDM_TIMEOUT_US 100000
#define DFSDM_TIMEOUT (msecs_to_jiffies(DFSDM_TIMEOUT_US / 1000))

/* Oversampling attribute default */
#define DFSDM_DEFAULT_OVERSAMPLING  100

/* Oversampling max values */
#define DFSDM_MAX_INT_OVERSAMPLING 256
#define DFSDM_MAX_FL_OVERSAMPLING 1024

/* Limit filter output resolution to 31 bits. (i.e. sample range is +/-2^30) */
#define DFSDM_DATA_MAX BIT(30)
/*
 * Data are output as two's complement data in a 24 bit field.
 * Data from filters are in the range +/-2^(n-1)
 * 2^(n-1) maximum positive value cannot be coded in 2's complement n bits
 * An extra bit is required to avoid wrap-around of the binary code for 2^(n-1)
 * So, the resolution of samples from filter is actually limited to 23 bits
 */
#define DFSDM_DATA_RES 24

/* Filter configuration */
#define DFSDM_CR1_CFG_MASK (DFSDM_CR1_RCH_MASK | DFSDM_CR1_RCONT_MASK | \
                            DFSDM_CR1_RSYNC_MASK | DFSDM_CR1_JSYNC_MASK | \
                            DFSDM_CR1_JSCAN_MASK)

enum sd_converter_type {
        DFSDM_AUDIO,
        DFSDM_IIO,
};

struct stm32_dfsdm_dev_data {
        int type;
        int (*init)(struct iio_dev *indio_dev);
        unsigned int num_channels;
        const struct regmap_config *regmap_cfg;
};

struct stm32_dfsdm_adc {
        struct stm32_dfsdm *dfsdm;
        const struct stm32_dfsdm_dev_data *dev_data;
        unsigned int fl_id;
        unsigned int nconv;
        unsigned long smask;

        /* ADC specific */
        unsigned int oversamp;
        struct iio_hw_consumer *hwc;
        struct completion completion;
        u32 *buffer;

        /* Audio specific */
        unsigned int spi_freq;  /* SPI bus clock frequency */
        unsigned int sample_freq; /* Sample frequency after filter decimation */
        int (*cb)(const void *data, size_t size, void *cb_priv);
        void *cb_priv;

        /* DMA */
        u8 *rx_buf;
        unsigned int bufi; /* Buffer current position */
        unsigned int buf_sz; /* Buffer size */
        struct dma_chan *dma_chan;
        dma_addr_t dma_buf;
};

struct stm32_dfsdm_str2field {
        const char      *name;
        unsigned int    val;
};

/* DFSDM channel serial interface type */
static const struct stm32_dfsdm_str2field stm32_dfsdm_chan_type[] = {
        { "SPI_R", 0 }, /* SPI with data on rising edge */
        { "SPI_F", 1 }, /* SPI with data on falling edge */
        { "MANCH_R", 2 }, /* Manchester codec, rising edge = logic 0 */
        { "MANCH_F", 3 }, /* Manchester codec, falling edge = logic 1 */
        {},
};

/* DFSDM channel clock source */
static const struct stm32_dfsdm_str2field stm32_dfsdm_chan_src[] = {
        /* External SPI clock (CLKIN x) */
        { "CLKIN", DFSDM_CHANNEL_SPI_CLOCK_EXTERNAL },
        /* Internal SPI clock (CLKOUT) */
        { "CLKOUT", DFSDM_CHANNEL_SPI_CLOCK_INTERNAL },
        /* Internal SPI clock divided by 2 (falling edge) */
        { "CLKOUT_F", DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_FALLING },
        /* Internal SPI clock divided by 2 (falling edge) */
        { "CLKOUT_R", DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_RISING },
        {},
};

static int stm32_dfsdm_str2val(const char *str,
                               const struct stm32_dfsdm_str2field *list)
{
        const struct stm32_dfsdm_str2field *p = list;

        for (p = list; p && p->name; p++)
                if (!strcmp(p->name, str))
                        return p->val;

        return -EINVAL;
}

/**
 * struct stm32_dfsdm_trig_info - DFSDM trigger info
 * @name:               name of the trigger, corresponding to its source
 * @jextsel:            trigger signal selection
 */
struct stm32_dfsdm_trig_info {
        const char *name;
        unsigned int jextsel;
};

/* hardware injected trigger enable, edge selection */
enum stm32_dfsdm_jexten {
        STM32_DFSDM_JEXTEN_DISABLED,
        STM32_DFSDM_JEXTEN_RISING_EDGE,
        STM32_DFSDM_JEXTEN_FALLING_EDGE,
        STM32_DFSDM_EXTEN_BOTH_EDGES,
};

static const struct stm32_dfsdm_trig_info stm32_dfsdm_trigs[] = {
        { TIM1_TRGO, 0 },
        { TIM1_TRGO2, 1 },
        { TIM8_TRGO, 2 },
        { TIM8_TRGO2, 3 },
        { TIM3_TRGO, 4 },
        { TIM4_TRGO, 5 },
        { TIM16_OC1, 6 },
        { TIM6_TRGO, 7 },
        { TIM7_TRGO, 8 },
        { LPTIM1_OUT, 26 },
        { LPTIM2_OUT, 27 },
        { LPTIM3_OUT, 28 },
        {},
};

static int stm32_dfsdm_get_jextsel(struct iio_dev *indio_dev,
                                   struct iio_trigger *trig)
{
        int i;

        /* lookup triggers registered by stm32 timer trigger driver */
        for (i = 0; stm32_dfsdm_trigs[i].name; i++) {
                /**
                 * Checking both stm32 timer trigger type and trig name
                 * should be safe against arbitrary trigger names.
                 */
                if ((is_stm32_timer_trigger(trig) ||
                     is_stm32_lptim_trigger(trig)) &&
                    !strcmp(stm32_dfsdm_trigs[i].name, trig->name)) {
                        return stm32_dfsdm_trigs[i].jextsel;
                }
        }

        return -EINVAL;
}

static int stm32_dfsdm_compute_osrs(struct stm32_dfsdm_filter *fl,
                                    unsigned int fast, unsigned int oversamp)
{
        unsigned int i, d, fosr, iosr;
        u64 res, max;
        int bits, shift;
        unsigned int m = 1;     /* multiplication factor */
        unsigned int p = fl->ford;      /* filter order (ford) */
        struct stm32_dfsdm_filter_osr *flo = &fl->flo[fast];

        pr_debug("%s: Requested oversampling: %d\n",  __func__, oversamp);
        /*
         * This function tries to compute filter oversampling and integrator
         * oversampling, base on oversampling ratio requested by user.
         *
         * Decimation d depends on the filter order and the oversampling ratios.
         * ford: filter order
         * fosr: filter over sampling ratio
         * iosr: integrator over sampling ratio
         */
        if (fl->ford == DFSDM_FASTSINC_ORDER) {
                m = 2;
                p = 2;
        }

        /*
         * Look for filter and integrator oversampling ratios which allows
         * to maximize data output resolution.
         */
        for (fosr = 1; fosr <= DFSDM_MAX_FL_OVERSAMPLING; fosr++) {
                for (iosr = 1; iosr <= DFSDM_MAX_INT_OVERSAMPLING; iosr++) {
                        if (fast)
                                d = fosr * iosr;
                        else if (fl->ford == DFSDM_FASTSINC_ORDER)
                                d = fosr * (iosr + 3) + 2;
                        else
                                d = fosr * (iosr - 1 + p) + p;

                        if (d > oversamp)
                                break;
                        else if (d != oversamp)
                                continue;
                        /*
                         * Check resolution (limited to signed 32 bits)
                         *   res <= 2^31
                         * Sincx filters:
                         *   res = m * fosr^p x iosr (with m=1, p=ford)
                         * FastSinc filter
                         *   res = m * fosr^p x iosr (with m=2, p=2)
                         */
                        res = fosr;
                        for (i = p - 1; i > 0; i--) {
                                res = res * (u64)fosr;
                                if (res > DFSDM_DATA_MAX)
                                        break;
                        }
                        if (res > DFSDM_DATA_MAX)
                                continue;

                        res = res * (u64)m * (u64)iosr;
                        if (res > DFSDM_DATA_MAX)
                                continue;

                        if (res >= flo->res) {
                                flo->res = res;
                                flo->fosr = fosr;
                                flo->iosr = iosr;

                                bits = fls(flo->res);
                                /* 8 LBSs in data register contain chan info */
                                max = flo->res << 8;

                                /* if resolution is not a power of two */
                                if (flo->res > BIT(bits - 1))
                                        bits++;
                                else
                                        max--;

                                shift = DFSDM_DATA_RES - bits;
                                /*
                                 * Compute right/left shift
                                 * Right shift is performed by hardware
                                 * when transferring samples to data register.
                                 * Left shift is done by software on buffer
                                 */
                                if (shift > 0) {
                                        /* Resolution is lower than 24 bits */
                                        flo->rshift = 0;
                                        flo->lshift = shift;
                                } else {
                                        /*
                                         * If resolution is 24 bits or more,
                                         * max positive value may be ambiguous
                                         * (equal to max negative value as sign
                                         * bit is dropped).
                                         * Reduce resolution to 23 bits (rshift)
                                         * to keep the sign on bit 23 and treat
                                         * saturation before rescaling on 24
                                         * bits (lshift).
                                         */
                                        flo->rshift = 1 - shift;
                                        flo->lshift = 1;
                                        max >>= flo->rshift;
                                }
                                flo->max = (s32)max;

                                pr_debug("%s: fast %d, fosr %d, iosr %d, res 0x%llx/%d bits, rshift %d, lshift %d\n",
                                         __func__, fast, flo->fosr, flo->iosr,
                                         flo->res, bits, flo->rshift,
                                         flo->lshift);
                        }
                }
        }

        if (!flo->res)
                return -EINVAL;

        return 0;
}

static int stm32_dfsdm_compute_all_osrs(struct iio_dev *indio_dev,
                                        unsigned int oversamp)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id];
        int ret0, ret1;

        memset(&fl->flo[0], 0, sizeof(fl->flo[0]));
        memset(&fl->flo[1], 0, sizeof(fl->flo[1]));

        ret0 = stm32_dfsdm_compute_osrs(fl, 0, oversamp);
        ret1 = stm32_dfsdm_compute_osrs(fl, 1, oversamp);
        if (ret0 < 0 && ret1 < 0) {
                dev_err(&indio_dev->dev,
                        "Filter parameters not found: errors %d/%d\n",
                        ret0, ret1);
                return -EINVAL;
        }

        return 0;
}

static int stm32_dfsdm_start_channel(struct stm32_dfsdm_adc *adc)
{
        struct iio_dev *indio_dev = iio_priv_to_dev(adc);
        struct regmap *regmap = adc->dfsdm->regmap;
        const struct iio_chan_spec *chan;
        unsigned int bit;
        int ret;

        for_each_set_bit(bit, &adc->smask, sizeof(adc->smask) * BITS_PER_BYTE) {
                chan = indio_dev->channels + bit;
                ret = regmap_update_bits(regmap, DFSDM_CHCFGR1(chan->channel),
                                         DFSDM_CHCFGR1_CHEN_MASK,
                                         DFSDM_CHCFGR1_CHEN(1));
                if (ret < 0)
                        return ret;
        }

        return 0;
}

static void stm32_dfsdm_stop_channel(struct stm32_dfsdm_adc *adc)
{
        struct iio_dev *indio_dev = iio_priv_to_dev(adc);
        struct regmap *regmap = adc->dfsdm->regmap;
        const struct iio_chan_spec *chan;
        unsigned int bit;

        for_each_set_bit(bit, &adc->smask, sizeof(adc->smask) * BITS_PER_BYTE) {
                chan = indio_dev->channels + bit;
                regmap_update_bits(regmap, DFSDM_CHCFGR1(chan->channel),
                                   DFSDM_CHCFGR1_CHEN_MASK,
                                   DFSDM_CHCFGR1_CHEN(0));
        }
}

static int stm32_dfsdm_chan_configure(struct stm32_dfsdm *dfsdm,
                                      struct stm32_dfsdm_channel *ch)
{
        unsigned int id = ch->id;
        struct regmap *regmap = dfsdm->regmap;
        int ret;

        ret = regmap_update_bits(regmap, DFSDM_CHCFGR1(id),
                                 DFSDM_CHCFGR1_SITP_MASK,
                                 DFSDM_CHCFGR1_SITP(ch->type));
        if (ret < 0)
                return ret;
        ret = regmap_update_bits(regmap, DFSDM_CHCFGR1(id),
                                 DFSDM_CHCFGR1_SPICKSEL_MASK,
                                 DFSDM_CHCFGR1_SPICKSEL(ch->src));
        if (ret < 0)
                return ret;
        return regmap_update_bits(regmap, DFSDM_CHCFGR1(id),
                                  DFSDM_CHCFGR1_CHINSEL_MASK,
                                  DFSDM_CHCFGR1_CHINSEL(ch->alt_si));
}

static int stm32_dfsdm_start_filter(struct stm32_dfsdm_adc *adc,
                                    unsigned int fl_id,
                                    struct iio_trigger *trig)
{
        struct stm32_dfsdm *dfsdm = adc->dfsdm;
        int ret;

        /* Enable filter */
        ret = regmap_update_bits(dfsdm->regmap, DFSDM_CR1(fl_id),
                                 DFSDM_CR1_DFEN_MASK, DFSDM_CR1_DFEN(1));
        if (ret < 0)
                return ret;

        /* Nothing more to do for injected (scan mode/triggered) conversions */
        if (adc->nconv > 1 || trig)
                return 0;

        /* Software start (single or continuous) regular conversion */
        return regmap_update_bits(dfsdm->regmap, DFSDM_CR1(fl_id),
                                  DFSDM_CR1_RSWSTART_MASK,
                                  DFSDM_CR1_RSWSTART(1));
}

static void stm32_dfsdm_stop_filter(struct stm32_dfsdm *dfsdm,
                                    unsigned int fl_id)
{
        /* Disable conversion */
        regmap_update_bits(dfsdm->regmap, DFSDM_CR1(fl_id),
                           DFSDM_CR1_DFEN_MASK, DFSDM_CR1_DFEN(0));
}

static int stm32_dfsdm_filter_set_trig(struct stm32_dfsdm_adc *adc,
                                       unsigned int fl_id,
                                       struct iio_trigger *trig)
{
        struct iio_dev *indio_dev = iio_priv_to_dev(adc);
        struct regmap *regmap = adc->dfsdm->regmap;
        u32 jextsel = 0, jexten = STM32_DFSDM_JEXTEN_DISABLED;
        int ret;

        if (trig) {
                ret = stm32_dfsdm_get_jextsel(indio_dev, trig);
                if (ret < 0)
                        return ret;

                /* set trigger source and polarity (default to rising edge) */
                jextsel = ret;
                jexten = STM32_DFSDM_JEXTEN_RISING_EDGE;
        }

        ret = regmap_update_bits(regmap, DFSDM_CR1(fl_id),
                                 DFSDM_CR1_JEXTSEL_MASK | DFSDM_CR1_JEXTEN_MASK,
                                 DFSDM_CR1_JEXTSEL(jextsel) |
                                 DFSDM_CR1_JEXTEN(jexten));
        if (ret < 0)
                return ret;

        return 0;
}

static int stm32_dfsdm_channels_configure(struct stm32_dfsdm_adc *adc,
                                          unsigned int fl_id,
                                          struct iio_trigger *trig)
{
        struct iio_dev *indio_dev = iio_priv_to_dev(adc);
        struct regmap *regmap = adc->dfsdm->regmap;
        struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[fl_id];
        struct stm32_dfsdm_filter_osr *flo = &fl->flo[0];
        const struct iio_chan_spec *chan;
        unsigned int bit;
        int ret;

        fl->fast = 0;

        /*
         * In continuous mode, use fast mode configuration,
         * if it provides a better resolution.
         */
        if (adc->nconv == 1 && !trig &&
            (indio_dev->currentmode & INDIO_BUFFER_SOFTWARE)) {
                if (fl->flo[1].res >= fl->flo[0].res) {
                        fl->fast = 1;
                        flo = &fl->flo[1];
                }
        }

        if (!flo->res)
                return -EINVAL;

        for_each_set_bit(bit, &adc->smask,
                         sizeof(adc->smask) * BITS_PER_BYTE) {
                chan = indio_dev->channels + bit;

                ret = regmap_update_bits(regmap,
                                         DFSDM_CHCFGR2(chan->channel),
                                         DFSDM_CHCFGR2_DTRBS_MASK,
                                         DFSDM_CHCFGR2_DTRBS(flo->rshift));
                if (ret)
                        return ret;
        }

        return 0;
}

static int stm32_dfsdm_filter_configure(struct stm32_dfsdm_adc *adc,
                                        unsigned int fl_id,
                                        struct iio_trigger *trig)
{
        struct iio_dev *indio_dev = iio_priv_to_dev(adc);
        struct regmap *regmap = adc->dfsdm->regmap;
        struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[fl_id];
        struct stm32_dfsdm_filter_osr *flo = &fl->flo[fl->fast];
        u32 cr1;
        const struct iio_chan_spec *chan;
        unsigned int bit, jchg = 0;
        int ret;

        /* Average integrator oversampling */
        ret = regmap_update_bits(regmap, DFSDM_FCR(fl_id), DFSDM_FCR_IOSR_MASK,
                                 DFSDM_FCR_IOSR(flo->iosr - 1));
        if (ret)
                return ret;

        /* Filter order and Oversampling */
        ret = regmap_update_bits(regmap, DFSDM_FCR(fl_id), DFSDM_FCR_FOSR_MASK,
                                 DFSDM_FCR_FOSR(flo->fosr - 1));
        if (ret)
                return ret;

        ret = regmap_update_bits(regmap, DFSDM_FCR(fl_id), DFSDM_FCR_FORD_MASK,
                                 DFSDM_FCR_FORD(fl->ford));
        if (ret)
                return ret;

        ret = stm32_dfsdm_filter_set_trig(adc, fl_id, trig);
        if (ret)
                return ret;

        ret = regmap_update_bits(regmap, DFSDM_CR1(fl_id),
                                 DFSDM_CR1_FAST_MASK,
                                 DFSDM_CR1_FAST(fl->fast));
        if (ret)
                return ret;

        /*
         * DFSDM modes configuration W.R.T audio/iio type modes
         * ----------------------------------------------------------------
         * Modes         | regular |  regular     | injected | injected   |
         *               |         |  continuous  |          | + scan     |
         * --------------|---------|--------------|----------|------------|
         * single conv   |    x    |              |          |            |
         * (1 chan)      |         |              |          |            |
         * --------------|---------|--------------|----------|------------|
         * 1 Audio chan  |         | sample freq  |          |            |
         *               |         | or sync_mode |          |            |
         * --------------|---------|--------------|----------|------------|
         * 1 IIO chan    |         | sample freq  | trigger  |            |
         *               |         | or sync_mode |          |            |
         * --------------|---------|--------------|----------|------------|
         * 2+ IIO chans  |         |              |          | trigger or |
         *               |         |              |          | sync_mode  |
         * ----------------------------------------------------------------
         */
        if (adc->nconv == 1 && !trig) {
                bit = __ffs(adc->smask);
                chan = indio_dev->channels + bit;

                /* Use regular conversion for single channel without trigger */
                cr1 = DFSDM_CR1_RCH(chan->channel);

                /* Continuous conversions triggered by SPI clk in buffer mode */
                if (indio_dev->currentmode & INDIO_BUFFER_SOFTWARE)
                        cr1 |= DFSDM_CR1_RCONT(1);

                cr1 |= DFSDM_CR1_RSYNC(fl->sync_mode);
        } else {
                /* Use injected conversion for multiple channels */
                for_each_set_bit(bit, &adc->smask,
                                 sizeof(adc->smask) * BITS_PER_BYTE) {
                        chan = indio_dev->channels + bit;
                        jchg |= BIT(chan->channel);
                }
                ret = regmap_write(regmap, DFSDM_JCHGR(fl_id), jchg);
                if (ret < 0)
                        return ret;

                /* Use scan mode for multiple channels */
                cr1 = DFSDM_CR1_JSCAN((adc->nconv > 1) ? 1 : 0);

                /*
                 * Continuous conversions not supported in injected mode,
                 * either use:
                 * - conversions in sync with filter 0
                 * - triggered conversions
                 */
                if (!fl->sync_mode && !trig)
                        return -EINVAL;
                cr1 |= DFSDM_CR1_JSYNC(fl->sync_mode);
        }

        return regmap_update_bits(regmap, DFSDM_CR1(fl_id), DFSDM_CR1_CFG_MASK,
                                  cr1);
}

static int stm32_dfsdm_channel_parse_of(struct stm32_dfsdm *dfsdm,
                                        struct iio_dev *indio_dev,
                                        struct iio_chan_spec *ch)
{
        struct stm32_dfsdm_channel *df_ch;
        const char *of_str;
        int chan_idx = ch->scan_index;
        int ret, val;

        ret = of_property_read_u32_index(indio_dev->dev.of_node,
                                         "st,adc-channels", chan_idx,
                                         &ch->channel);
        if (ret < 0) {
                dev_err(&indio_dev->dev,
                        " Error parsing 'st,adc-channels' for idx %d\n",
                        chan_idx);
                return ret;
        }
        if (ch->channel >= dfsdm->num_chs) {
                dev_err(&indio_dev->dev,
                        " Error bad channel number %d (max = %d)\n",
                        ch->channel, dfsdm->num_chs);
                return -EINVAL;
        }

        ret = of_property_read_string_index(indio_dev->dev.of_node,
                                            "st,adc-channel-names", chan_idx,
                                            &ch->datasheet_name);
        if (ret < 0) {
                dev_err(&indio_dev->dev,
                        " Error parsing 'st,adc-channel-names' for idx %d\n",
                        chan_idx);
                return ret;
        }

        df_ch =  &dfsdm->ch_list[ch->channel];
        df_ch->id = ch->channel;

        ret = of_property_read_string_index(indio_dev->dev.of_node,
                                            "st,adc-channel-types", chan_idx,
                                            &of_str);
        if (!ret) {
                val = stm32_dfsdm_str2val(of_str, stm32_dfsdm_chan_type);
                if (val < 0)
                        return val;
        } else {
                val = 0;
        }
        df_ch->type = val;

        ret = of_property_read_string_index(indio_dev->dev.of_node,
                                            "st,adc-channel-clk-src", chan_idx,
                                            &of_str);
        if (!ret) {
                val = stm32_dfsdm_str2val(of_str, stm32_dfsdm_chan_src);
                if (val < 0)
                        return val;
        } else {
                val = 0;
        }
        df_ch->src = val;

        ret = of_property_read_u32_index(indio_dev->dev.of_node,
                                         "st,adc-alt-channel", chan_idx,
                                         &df_ch->alt_si);
        if (ret < 0)
                df_ch->alt_si = 0;

        return 0;
}

static ssize_t dfsdm_adc_audio_get_spiclk(struct iio_dev *indio_dev,
                                          uintptr_t priv,
                                          const struct iio_chan_spec *chan,
                                          char *buf)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);

        return snprintf(buf, PAGE_SIZE, "%d\n", adc->spi_freq);
}

static int dfsdm_adc_set_samp_freq(struct iio_dev *indio_dev,
                                   unsigned int sample_freq,
                                   unsigned int spi_freq)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        unsigned int oversamp;
        int ret;

        oversamp = DIV_ROUND_CLOSEST(spi_freq, sample_freq);
        if (spi_freq % sample_freq)
                dev_dbg(&indio_dev->dev,
                        "Rate not accurate. requested (%u), actual (%u)\n",
                        sample_freq, spi_freq / oversamp);

        ret = stm32_dfsdm_compute_all_osrs(indio_dev, oversamp);
        if (ret < 0)
                return ret;

        adc->sample_freq = spi_freq / oversamp;
        adc->oversamp = oversamp;

        return 0;
}

static ssize_t dfsdm_adc_audio_set_spiclk(struct iio_dev *indio_dev,
                                          uintptr_t priv,
                                          const struct iio_chan_spec *chan,
                                          const char *buf, size_t len)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        struct stm32_dfsdm_channel *ch = &adc->dfsdm->ch_list[chan->channel];
        unsigned int sample_freq = adc->sample_freq;
        unsigned int spi_freq;
        int ret;

        dev_err(&indio_dev->dev, "enter %s\n", __func__);
        /* If DFSDM is master on SPI, SPI freq can not be updated */
        if (ch->src != DFSDM_CHANNEL_SPI_CLOCK_EXTERNAL)
                return -EPERM;

        ret = kstrtoint(buf, 0, &spi_freq);
        if (ret)
                return ret;

        if (!spi_freq)
                return -EINVAL;

        if (sample_freq) {
                ret = dfsdm_adc_set_samp_freq(indio_dev, sample_freq, spi_freq);
                if (ret < 0)
                        return ret;
        }
        adc->spi_freq = spi_freq;

        return len;
}

static int stm32_dfsdm_start_conv(struct stm32_dfsdm_adc *adc,
                                  struct iio_trigger *trig)
{
        struct regmap *regmap = adc->dfsdm->regmap;
        int ret;

        ret = stm32_dfsdm_channels_configure(adc, adc->fl_id, trig);
        if (ret < 0)
                return ret;

        ret = stm32_dfsdm_start_channel(adc);
        if (ret < 0)
                return ret;

        ret = stm32_dfsdm_filter_configure(adc, adc->fl_id, trig);
        if (ret < 0)
                goto stop_channels;

        ret = stm32_dfsdm_start_filter(adc, adc->fl_id, trig);
        if (ret < 0)
                goto filter_unconfigure;

        return 0;

filter_unconfigure:
        regmap_update_bits(regmap, DFSDM_CR1(adc->fl_id),
                           DFSDM_CR1_CFG_MASK, 0);
stop_channels:
        stm32_dfsdm_stop_channel(adc);

        return ret;
}

static void stm32_dfsdm_stop_conv(struct stm32_dfsdm_adc *adc)
{
        struct regmap *regmap = adc->dfsdm->regmap;

        stm32_dfsdm_stop_filter(adc->dfsdm, adc->fl_id);

        regmap_update_bits(regmap, DFSDM_CR1(adc->fl_id),
                           DFSDM_CR1_CFG_MASK, 0);

        stm32_dfsdm_stop_channel(adc);
}

static int stm32_dfsdm_set_watermark(struct iio_dev *indio_dev,
                                     unsigned int val)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        unsigned int watermark = DFSDM_DMA_BUFFER_SIZE / 2;
        unsigned int rx_buf_sz = DFSDM_DMA_BUFFER_SIZE;

        /*
         * DMA cyclic transfers are used, buffer is split into two periods.
         * There should be :
         * - always one buffer (period) DMA is working on
         * - one buffer (period) driver pushed to ASoC side.
         */
        watermark = min(watermark, val * (unsigned int)(sizeof(u32)));
        adc->buf_sz = min(rx_buf_sz, watermark * 2 * adc->nconv);

        return 0;
}

static unsigned int stm32_dfsdm_adc_dma_residue(struct stm32_dfsdm_adc *adc)
{
        struct dma_tx_state state;
        enum dma_status status;

        status = dmaengine_tx_status(adc->dma_chan,
                                     adc->dma_chan->cookie,
                                     &state);
        if (status == DMA_IN_PROGRESS) {
                /* Residue is size in bytes from end of buffer */
                unsigned int i = adc->buf_sz - state.residue;
                unsigned int size;

                /* Return available bytes */
                if (i >= adc->bufi)
                        size = i - adc->bufi;
                else
                        size = adc->buf_sz + i - adc->bufi;

                return size;
        }

        return 0;
}

static inline void stm32_dfsdm_process_data(struct stm32_dfsdm_adc *adc,
                                            s32 *buffer)
{
        struct stm32_dfsdm_filter *fl = &adc->dfsdm->fl_list[adc->fl_id];
        struct stm32_dfsdm_filter_osr *flo = &fl->flo[fl->fast];
        unsigned int i = adc->nconv;
        s32 *ptr = buffer;

        while (i--) {
                /* Mask 8 LSB that contains the channel ID */
                *ptr &= 0xFFFFFF00;
                /* Convert 2^(n-1) sample to 2^(n-1)-1 to avoid wrap-around */
                if (*ptr > flo->max)
                        *ptr -= 1;
                /*
                 * Samples from filter are retrieved with 23 bits resolution
                 * or less. Shift left to align MSB on 24 bits.
                 */
                *ptr <<= flo->lshift;

                ptr++;
        }
}

static void stm32_dfsdm_dma_buffer_done(void *data)
{
        struct iio_dev *indio_dev = data;
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        int available = stm32_dfsdm_adc_dma_residue(adc);
        size_t old_pos;

        /*
         * FIXME: In Kernel interface does not support cyclic DMA buffer,and
         * offers only an interface to push data samples per samples.
         * For this reason IIO buffer interface is not used and interface is
         * bypassed using a private callback registered by ASoC.
         * This should be a temporary solution waiting a cyclic DMA engine
         * support in IIO.
         */

        dev_dbg(&indio_dev->dev, "%s: pos = %d, available = %d\n", __func__,
                adc->bufi, available);
        old_pos = adc->bufi;

        while (available >= indio_dev->scan_bytes) {
                s32 *buffer = (s32 *)&adc->rx_buf[adc->bufi];

                stm32_dfsdm_process_data(adc, buffer);

                available -= indio_dev->scan_bytes;
                adc->bufi += indio_dev->scan_bytes;
                if (adc->bufi >= adc->buf_sz) {
                        if (adc->cb)
                                adc->cb(&adc->rx_buf[old_pos],
                                         adc->buf_sz - old_pos, adc->cb_priv);
                        adc->bufi = 0;
                        old_pos = 0;
                }
                /*
                 * In DMA mode the trigger services of IIO are not used
                 * (e.g. no call to iio_trigger_poll).
                 * Calling irq handler associated to the hardware trigger is not
                 * relevant as the conversions have already been done. Data
                 * transfers are performed directly in DMA callback instead.
                 * This implementation avoids to call trigger irq handler that
                 * may sleep, in an atomic context (DMA irq handler context).
                 */
                if (adc->dev_data->type == DFSDM_IIO)
                        iio_push_to_buffers(indio_dev, buffer);
        }
        if (adc->cb)
                adc->cb(&adc->rx_buf[old_pos], adc->bufi - old_pos,
                        adc->cb_priv);
}

static int stm32_dfsdm_adc_dma_start(struct iio_dev *indio_dev)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        /*
         * The DFSDM supports half-word transfers. However, for 16 bits record,
         * 4 bytes buswidth is kept, to avoid losing samples LSBs when left
         * shift is required.
         */
        struct dma_slave_config config = {
                .src_addr = (dma_addr_t)adc->dfsdm->phys_base,
                .src_addr_width = DMA_SLAVE_BUSWIDTH_4_BYTES,
        };
        struct dma_async_tx_descriptor *desc;
        dma_cookie_t cookie;
        int ret;

        if (!adc->dma_chan)
                return -EINVAL;

        dev_dbg(&indio_dev->dev, "%s size=%d watermark=%d\n", __func__,
                adc->buf_sz, adc->buf_sz / 2);

        if (adc->nconv == 1 && !indio_dev->trig)
                config.src_addr += DFSDM_RDATAR(adc->fl_id);
        else
                config.src_addr += DFSDM_JDATAR(adc->fl_id);
        ret = dmaengine_slave_config(adc->dma_chan, &config);
        if (ret)
                return ret;

        /* Prepare a DMA cyclic transaction */
        desc = dmaengine_prep_dma_cyclic(adc->dma_chan,
                                         adc->dma_buf,
                                         adc->buf_sz, adc->buf_sz / 2,
                                         DMA_DEV_TO_MEM,
                                         DMA_PREP_INTERRUPT);
        if (!desc)
                return -EBUSY;

        desc->callback = stm32_dfsdm_dma_buffer_done;
        desc->callback_param = indio_dev;

        cookie = dmaengine_submit(desc);
        ret = dma_submit_error(cookie);
        if (ret)
                goto err_stop_dma;

        /* Issue pending DMA requests */
        dma_async_issue_pending(adc->dma_chan);

        if (adc->nconv == 1 && !indio_dev->trig) {
                /* Enable regular DMA transfer*/
                ret = regmap_update_bits(adc->dfsdm->regmap,
                                         DFSDM_CR1(adc->fl_id),
                                         DFSDM_CR1_RDMAEN_MASK,
                                         DFSDM_CR1_RDMAEN_MASK);
        } else {
                /* Enable injected DMA transfer*/
                ret = regmap_update_bits(adc->dfsdm->regmap,
                                         DFSDM_CR1(adc->fl_id),
                                         DFSDM_CR1_JDMAEN_MASK,
                                         DFSDM_CR1_JDMAEN_MASK);
        }

        if (ret < 0)
                goto err_stop_dma;

        return 0;

err_stop_dma:
        dmaengine_terminate_all(adc->dma_chan);

        return ret;
}

static void stm32_dfsdm_adc_dma_stop(struct iio_dev *indio_dev)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);

        if (!adc->dma_chan)
                return;

        regmap_update_bits(adc->dfsdm->regmap, DFSDM_CR1(adc->fl_id),
                           DFSDM_CR1_RDMAEN_MASK | DFSDM_CR1_JDMAEN_MASK, 0);
        dmaengine_terminate_all(adc->dma_chan);
}

static int stm32_dfsdm_update_scan_mode(struct iio_dev *indio_dev,
                                        const unsigned long *scan_mask)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);

        adc->nconv = bitmap_weight(scan_mask, indio_dev->masklength);
        adc->smask = *scan_mask;

        dev_dbg(&indio_dev->dev, "nconv=%d mask=%lx\n", adc->nconv, *scan_mask);

        return 0;
}

static int __stm32_dfsdm_postenable(struct iio_dev *indio_dev)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        int ret;

        /* Reset adc buffer index */
        adc->bufi = 0;

        if (adc->hwc) {
                ret = iio_hw_consumer_enable(adc->hwc);
                if (ret < 0)
                        return ret;
        }

        ret = stm32_dfsdm_start_dfsdm(adc->dfsdm);
        if (ret < 0)
                goto err_stop_hwc;

        ret = stm32_dfsdm_adc_dma_start(indio_dev);
        if (ret) {
                dev_err(&indio_dev->dev, "Can't start DMA\n");
                goto stop_dfsdm;
        }

        ret = stm32_dfsdm_start_conv(adc, indio_dev->trig);
        if (ret) {
                dev_err(&indio_dev->dev, "Can't start conversion\n");
                goto err_stop_dma;
        }

        return 0;

err_stop_dma:
        stm32_dfsdm_adc_dma_stop(indio_dev);
stop_dfsdm:
        stm32_dfsdm_stop_dfsdm(adc->dfsdm);
err_stop_hwc:
        if (adc->hwc)
                iio_hw_consumer_disable(adc->hwc);

        return ret;
}

static int stm32_dfsdm_postenable(struct iio_dev *indio_dev)
{
        int ret;

        if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
                ret = iio_triggered_buffer_postenable(indio_dev);
                if (ret < 0)
                        return ret;
        }

        ret = __stm32_dfsdm_postenable(indio_dev);
        if (ret < 0)
                goto err_predisable;

        return 0;

err_predisable:
        if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED)
                iio_triggered_buffer_predisable(indio_dev);

        return ret;
}

static void __stm32_dfsdm_predisable(struct iio_dev *indio_dev)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);

        stm32_dfsdm_stop_conv(adc);

        stm32_dfsdm_adc_dma_stop(indio_dev);

        stm32_dfsdm_stop_dfsdm(adc->dfsdm);

        if (adc->hwc)
                iio_hw_consumer_disable(adc->hwc);
}

static int stm32_dfsdm_predisable(struct iio_dev *indio_dev)
{
        __stm32_dfsdm_predisable(indio_dev);

        if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED)
                iio_triggered_buffer_predisable(indio_dev);

        return 0;
}

static const struct iio_buffer_setup_ops stm32_dfsdm_buffer_setup_ops = {
        .postenable = &stm32_dfsdm_postenable,
        .predisable = &stm32_dfsdm_predisable,
};

/**
 * stm32_dfsdm_get_buff_cb() - register a callback that will be called when
 *                             DMA transfer period is achieved.
 *
 * @iio_dev: Handle to IIO device.
 * @cb: Pointer to callback function:
 *      - data: pointer to data buffer
 *      - size: size in byte of the data buffer
 *      - private: pointer to consumer private structure.
 * @private: Pointer to consumer private structure.
 */
int stm32_dfsdm_get_buff_cb(struct iio_dev *iio_dev,
                            int (*cb)(const void *data, size_t size,
                                      void *private),
                            void *private)
{
        struct stm32_dfsdm_adc *adc;

        if (!iio_dev)
                return -EINVAL;
        adc = iio_priv(iio_dev);

        adc->cb = cb;
        adc->cb_priv = private;

        return 0;
}
EXPORT_SYMBOL_GPL(stm32_dfsdm_get_buff_cb);

/**
 * stm32_dfsdm_release_buff_cb - unregister buffer callback
 *
 * @iio_dev: Handle to IIO device.
 */
int stm32_dfsdm_release_buff_cb(struct iio_dev *iio_dev)
{
        struct stm32_dfsdm_adc *adc;

        if (!iio_dev)
                return -EINVAL;
        adc = iio_priv(iio_dev);

        adc->cb = NULL;
        adc->cb_priv = NULL;

        return 0;
}
EXPORT_SYMBOL_GPL(stm32_dfsdm_release_buff_cb);

static int stm32_dfsdm_single_conv(struct iio_dev *indio_dev,
                                   const struct iio_chan_spec *chan, int *res)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        long timeout;
        int ret;

        reinit_completion(&adc->completion);

        adc->buffer = res;

        ret = stm32_dfsdm_start_dfsdm(adc->dfsdm);
        if (ret < 0)
                return ret;

        ret = regmap_update_bits(adc->dfsdm->regmap, DFSDM_CR2(adc->fl_id),
                                 DFSDM_CR2_REOCIE_MASK, DFSDM_CR2_REOCIE(1));
        if (ret < 0)
                goto stop_dfsdm;

        adc->nconv = 1;
        adc->smask = BIT(chan->scan_index);
        ret = stm32_dfsdm_start_conv(adc, NULL);
        if (ret < 0) {
                regmap_update_bits(adc->dfsdm->regmap, DFSDM_CR2(adc->fl_id),
                                   DFSDM_CR2_REOCIE_MASK, DFSDM_CR2_REOCIE(0));
                goto stop_dfsdm;
        }

        timeout = wait_for_completion_interruptible_timeout(&adc->completion,
                                                            DFSDM_TIMEOUT);

        /* Mask IRQ for regular conversion achievement*/
        regmap_update_bits(adc->dfsdm->regmap, DFSDM_CR2(adc->fl_id),
                           DFSDM_CR2_REOCIE_MASK, DFSDM_CR2_REOCIE(0));

        if (timeout == 0)
                ret = -ETIMEDOUT;
        else if (timeout < 0)
                ret = timeout;
        else
                ret = IIO_VAL_INT;

        stm32_dfsdm_stop_conv(adc);

        stm32_dfsdm_process_data(adc, res);

stop_dfsdm:
        stm32_dfsdm_stop_dfsdm(adc->dfsdm);

        return ret;
}

static int stm32_dfsdm_write_raw(struct iio_dev *indio_dev,
                                 struct iio_chan_spec const *chan,
                                 int val, int val2, long mask)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        struct stm32_dfsdm_channel *ch = &adc->dfsdm->ch_list[chan->channel];
        unsigned int spi_freq;
        int ret = -EINVAL;

        switch (ch->src) {
        case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL:
                spi_freq = adc->dfsdm->spi_master_freq;
                break;
        case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_FALLING:
        case DFSDM_CHANNEL_SPI_CLOCK_INTERNAL_DIV2_RISING:
                spi_freq = adc->dfsdm->spi_master_freq / 2;
                break;
        default:
                spi_freq = adc->spi_freq;
        }

        switch (mask) {
        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                ret = iio_device_claim_direct_mode(indio_dev);
                if (ret)
                        return ret;

                ret = stm32_dfsdm_compute_all_osrs(indio_dev, val);
                if (!ret) {
                        dev_dbg(&indio_dev->dev,
                                "Sampling rate changed from (%u) to (%u)\n",
                                adc->sample_freq, spi_freq / val);
                        adc->oversamp = val;
                        adc->sample_freq = spi_freq / val;
                }
                iio_device_release_direct_mode(indio_dev);
                return ret;

        case IIO_CHAN_INFO_SAMP_FREQ:
                if (!val)
                        return -EINVAL;

                ret = iio_device_claim_direct_mode(indio_dev);
                if (ret)
                        return ret;

                ret = dfsdm_adc_set_samp_freq(indio_dev, val, spi_freq);
                iio_device_release_direct_mode(indio_dev);
                return ret;
        }

        return -EINVAL;
}

static int stm32_dfsdm_read_raw(struct iio_dev *indio_dev,
                                struct iio_chan_spec const *chan, int *val,
                                int *val2, long mask)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                ret = iio_device_claim_direct_mode(indio_dev);
                if (ret)
                        return ret;
                ret = iio_hw_consumer_enable(adc->hwc);
                if (ret < 0) {
                        dev_err(&indio_dev->dev,
                                "%s: IIO enable failed (channel %d)\n",
                                __func__, chan->channel);
                        iio_device_release_direct_mode(indio_dev);
                        return ret;
                }
                ret = stm32_dfsdm_single_conv(indio_dev, chan, val);
                iio_hw_consumer_disable(adc->hwc);
                if (ret < 0) {
                        dev_err(&indio_dev->dev,
                                "%s: Conversion failed (channel %d)\n",
                                __func__, chan->channel);
                        iio_device_release_direct_mode(indio_dev);
                        return ret;
                }
                iio_device_release_direct_mode(indio_dev);
                return IIO_VAL_INT;

        case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
                *val = adc->oversamp;

                return IIO_VAL_INT;

        case IIO_CHAN_INFO_SAMP_FREQ:
                *val = adc->sample_freq;

                return IIO_VAL_INT;
        }

        return -EINVAL;
}

static int stm32_dfsdm_validate_trigger(struct iio_dev *indio_dev,
                                        struct iio_trigger *trig)
{
        return stm32_dfsdm_get_jextsel(indio_dev, trig) < 0 ? -EINVAL : 0;
}

static const struct iio_info stm32_dfsdm_info_audio = {
        .hwfifo_set_watermark = stm32_dfsdm_set_watermark,
        .read_raw = stm32_dfsdm_read_raw,
        .write_raw = stm32_dfsdm_write_raw,
        .update_scan_mode = stm32_dfsdm_update_scan_mode,
};

static const struct iio_info stm32_dfsdm_info_adc = {
        .hwfifo_set_watermark = stm32_dfsdm_set_watermark,
        .read_raw = stm32_dfsdm_read_raw,
        .write_raw = stm32_dfsdm_write_raw,
        .update_scan_mode = stm32_dfsdm_update_scan_mode,
        .validate_trigger = stm32_dfsdm_validate_trigger,
};

static irqreturn_t stm32_dfsdm_irq(int irq, void *arg)
{
        struct stm32_dfsdm_adc *adc = arg;
        struct iio_dev *indio_dev = iio_priv_to_dev(adc);
        struct regmap *regmap = adc->dfsdm->regmap;
        unsigned int status, int_en;

        regmap_read(regmap, DFSDM_ISR(adc->fl_id), &status);
        regmap_read(regmap, DFSDM_CR2(adc->fl_id), &int_en);

        if (status & DFSDM_ISR_REOCF_MASK) {
                /* Read the data register clean the IRQ status */
                regmap_read(regmap, DFSDM_RDATAR(adc->fl_id), adc->buffer);
                complete(&adc->completion);
        }

        if (status & DFSDM_ISR_ROVRF_MASK) {
                if (int_en & DFSDM_CR2_ROVRIE_MASK)
                        dev_warn(&indio_dev->dev, "Overrun detected\n");
                regmap_update_bits(regmap, DFSDM_ICR(adc->fl_id),
                                   DFSDM_ICR_CLRROVRF_MASK,
                                   DFSDM_ICR_CLRROVRF_MASK);
        }

        return IRQ_HANDLED;
}

/*
 * Define external info for SPI Frequency and audio sampling rate that can be
 * configured by ASoC driver through consumer.h API
 */
static const struct iio_chan_spec_ext_info dfsdm_adc_audio_ext_info[] = {
        /* spi_clk_freq : clock freq on SPI/manchester bus used by channel */
        {
                .name = "spi_clk_freq",
                .shared = IIO_SHARED_BY_TYPE,
                .read = dfsdm_adc_audio_get_spiclk,
                .write = dfsdm_adc_audio_set_spiclk,
        },
        {},
};

static void stm32_dfsdm_dma_release(struct iio_dev *indio_dev)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);

        if (adc->dma_chan) {
                dma_free_coherent(adc->dma_chan->device->dev,
                                  DFSDM_DMA_BUFFER_SIZE,
                                  adc->rx_buf, adc->dma_buf);
                dma_release_channel(adc->dma_chan);
        }
}

static int stm32_dfsdm_dma_request(struct iio_dev *indio_dev)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);

        adc->dma_chan = dma_request_chan(&indio_dev->dev, "rx");
        if (IS_ERR(adc->dma_chan)) {
                int ret = PTR_ERR(adc->dma_chan);

                adc->dma_chan = NULL;
                return ret;
        }

        adc->rx_buf = dma_alloc_coherent(adc->dma_chan->device->dev,
                                         DFSDM_DMA_BUFFER_SIZE,
                                         &adc->dma_buf, GFP_KERNEL);
        if (!adc->rx_buf) {
                dma_release_channel(adc->dma_chan);
                return -ENOMEM;
        }

        indio_dev->modes |= INDIO_BUFFER_SOFTWARE;
        indio_dev->setup_ops = &stm32_dfsdm_buffer_setup_ops;

        return 0;
}

static int stm32_dfsdm_adc_chan_init_one(struct iio_dev *indio_dev,
                                         struct iio_chan_spec *ch)
{
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        int ret;

        ret = stm32_dfsdm_channel_parse_of(adc->dfsdm, indio_dev, ch);
        if (ret < 0)
                return ret;

        ch->type = IIO_VOLTAGE;
        ch->indexed = 1;

        /*
         * IIO_CHAN_INFO_RAW: used to compute regular conversion
         * IIO_CHAN_INFO_OVERSAMPLING_RATIO: used to set oversampling
         */
        ch->info_mask_separate = BIT(IIO_CHAN_INFO_RAW);
        ch->info_mask_shared_by_all = BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
                                        BIT(IIO_CHAN_INFO_SAMP_FREQ);

        if (adc->dev_data->type == DFSDM_AUDIO) {
                ch->ext_info = dfsdm_adc_audio_ext_info;
        } else {
                ch->scan_type.shift = 8;
        }
        ch->scan_type.sign = 's';
        ch->scan_type.realbits = 24;
        ch->scan_type.storagebits = 32;

        return stm32_dfsdm_chan_configure(adc->dfsdm,
                                          &adc->dfsdm->ch_list[ch->channel]);
}

static int stm32_dfsdm_audio_init(struct iio_dev *indio_dev)
{
        struct iio_chan_spec *ch;
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        struct stm32_dfsdm_channel *d_ch;
        int ret;

        ch = devm_kzalloc(&indio_dev->dev, sizeof(*ch), GFP_KERNEL);
        if (!ch)
                return -ENOMEM;

        ch->scan_index = 0;

        ret = stm32_dfsdm_adc_chan_init_one(indio_dev, ch);
        if (ret < 0) {
                dev_err(&indio_dev->dev, "Channels init failed\n");
                return ret;
        }
        ch->info_mask_separate = BIT(IIO_CHAN_INFO_SAMP_FREQ);

        d_ch = &adc->dfsdm->ch_list[ch->channel];
        if (d_ch->src != DFSDM_CHANNEL_SPI_CLOCK_EXTERNAL)
                adc->spi_freq = adc->dfsdm->spi_master_freq;

        indio_dev->num_channels = 1;
        indio_dev->channels = ch;

        return stm32_dfsdm_dma_request(indio_dev);
}

static int stm32_dfsdm_adc_init(struct iio_dev *indio_dev)
{
        struct iio_chan_spec *ch;
        struct stm32_dfsdm_adc *adc = iio_priv(indio_dev);
        int num_ch;
        int ret, chan_idx;

        adc->oversamp = DFSDM_DEFAULT_OVERSAMPLING;
        ret = stm32_dfsdm_compute_all_osrs(indio_dev, adc->oversamp);
        if (ret < 0)
                return ret;

        num_ch = of_property_count_u32_elems(indio_dev->dev.of_node,
                                             "st,adc-channels");
        if (num_ch < 0 || num_ch > adc->dfsdm->num_chs) {
                dev_err(&indio_dev->dev, "Bad st,adc-channels\n");
                return num_ch < 0 ? num_ch : -EINVAL;
        }

        /* Bind to SD modulator IIO device */
        adc->hwc = devm_iio_hw_consumer_alloc(&indio_dev->dev);
        if (IS_ERR(adc->hwc))
                return -EPROBE_DEFER;

        ch = devm_kcalloc(&indio_dev->dev, num_ch, sizeof(*ch),
                          GFP_KERNEL);
        if (!ch)
                return -ENOMEM;

        for (chan_idx = 0; chan_idx < num_ch; chan_idx++) {
                ch[chan_idx].scan_index = chan_idx;
                ret = stm32_dfsdm_adc_chan_init_one(indio_dev, &ch[chan_idx]);
                if (ret < 0) {
                        dev_err(&indio_dev->dev, "Channels init failed\n");
                        return ret;
                }
        }

        indio_dev->num_channels = num_ch;
        indio_dev->channels = ch;

        init_completion(&adc->completion);

        /* Optionally request DMA */
        ret = stm32_dfsdm_dma_request(indio_dev);
        if (ret) {
                if (ret != -ENODEV) {
                        if (ret != -EPROBE_DEFER)
                                dev_err(&indio_dev->dev,
                                        "DMA channel request failed with %d\n",
                                        ret);
                        return ret;
                }

                dev_dbg(&indio_dev->dev, "No DMA support\n");
                return 0;
        }

        ret = iio_triggered_buffer_setup(indio_dev,
                                         &iio_pollfunc_store_time, NULL,
                                         &stm32_dfsdm_buffer_setup_ops);
        if (ret) {
                stm32_dfsdm_dma_release(indio_dev);
                dev_err(&indio_dev->dev, "buffer setup failed\n");
                return ret;
        }

        /* lptimer/timer hardware triggers */
        indio_dev->modes |= INDIO_HARDWARE_TRIGGERED;

        return 0;
}

static const struct stm32_dfsdm_dev_data stm32h7_dfsdm_adc_data = {
        .type = DFSDM_IIO,
        .init = stm32_dfsdm_adc_init,
};

static const struct stm32_dfsdm_dev_data stm32h7_dfsdm_audio_data = {
        .type = DFSDM_AUDIO,
        .init = stm32_dfsdm_audio_init,
};

static const struct of_device_id stm32_dfsdm_adc_match[] = {
        {
                .compatible = "st,stm32-dfsdm-adc",
                .data = &stm32h7_dfsdm_adc_data,
        },
        {
                .compatible = "st,stm32-dfsdm-dmic",
                .data = &stm32h7_dfsdm_audio_data,
        },
        {}
};

static int stm32_dfsdm_adc_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct stm32_dfsdm_adc *adc;
        struct device_node *np = dev->of_node;
        const struct stm32_dfsdm_dev_data *dev_data;
        struct iio_dev *iio;
        char *name;
        int ret, irq, val;

        dev_data = of_device_get_match_data(dev);
        iio = devm_iio_device_alloc(dev, sizeof(*adc));
        if (!iio) {
                dev_err(dev, "%s: Failed to allocate IIO\n", __func__);
                return -ENOMEM;
        }

        adc = iio_priv(iio);
        adc->dfsdm = dev_get_drvdata(dev->parent);

        iio->dev.parent = dev;
        iio->dev.of_node = np;
        iio->modes = INDIO_DIRECT_MODE;

        platform_set_drvdata(pdev, adc);

        ret = of_property_read_u32(dev->of_node, "reg", &adc->fl_id);
        if (ret != 0 || adc->fl_id >= adc->dfsdm->num_fls) {
                dev_err(dev, "Missing or bad reg property\n");
                return -EINVAL;
        }

        name = devm_kzalloc(dev, sizeof("dfsdm-adc0"), GFP_KERNEL);
        if (!name)
                return -ENOMEM;
        if (dev_data->type == DFSDM_AUDIO) {
                iio->info = &stm32_dfsdm_info_audio;
                snprintf(name, sizeof("dfsdm-pdm0"), "dfsdm-pdm%d", adc->fl_id);
        } else {
                iio->info = &stm32_dfsdm_info_adc;
                snprintf(name, sizeof("dfsdm-adc0"), "dfsdm-adc%d", adc->fl_id);
        }
        iio->name = name;

        /*
         * In a first step IRQs generated for channels are not treated.
         * So IRQ associated to filter instance 0 is dedicated to the Filter 0.
         */
        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return irq;

        ret = devm_request_irq(dev, irq, stm32_dfsdm_irq,
                               0, pdev->name, adc);
        if (ret < 0) {
                dev_err(dev, "Failed to request IRQ\n");
                return ret;
        }

        ret = of_property_read_u32(dev->of_node, "st,filter-order", &val);
        if (ret < 0) {
                dev_err(dev, "Failed to set filter order\n");
                return ret;
        }

        adc->dfsdm->fl_list[adc->fl_id].ford = val;

        ret = of_property_read_u32(dev->of_node, "st,filter0-sync", &val);
        if (!ret)
                adc->dfsdm->fl_list[adc->fl_id].sync_mode = val;

        adc->dev_data = dev_data;
        ret = dev_data->init(iio);
        if (ret < 0)
                return ret;

        ret = iio_device_register(iio);
        if (ret < 0)
                goto err_cleanup;

        if (dev_data->type == DFSDM_AUDIO) {
                ret = of_platform_populate(np, NULL, NULL, dev);
                if (ret < 0) {
                        dev_err(dev, "Failed to find an audio DAI\n");
                        goto err_unregister;
                }
        }

        return 0;

err_unregister:
        iio_device_unregister(iio);
err_cleanup:
        stm32_dfsdm_dma_release(iio);

        return ret;
}

static int stm32_dfsdm_adc_remove(struct platform_device *pdev)
{
        struct stm32_dfsdm_adc *adc = platform_get_drvdata(pdev);
        struct iio_dev *indio_dev = iio_priv_to_dev(adc);

        if (adc->dev_data->type == DFSDM_AUDIO)
                of_platform_depopulate(&pdev->dev);
        iio_device_unregister(indio_dev);
        stm32_dfsdm_dma_release(indio_dev);

        return 0;
}

static int __maybe_unused stm32_dfsdm_adc_suspend(struct device *dev)
{
        struct stm32_dfsdm_adc *adc = dev_get_drvdata(dev);
        struct iio_dev *indio_dev = iio_priv_to_dev(adc);

        if (iio_buffer_enabled(indio_dev))
                __stm32_dfsdm_predisable(indio_dev);

        return 0;
}

static int __maybe_unused stm32_dfsdm_adc_resume(struct device *dev)
{
        struct stm32_dfsdm_adc *adc = dev_get_drvdata(dev);
        struct iio_dev *indio_dev = iio_priv_to_dev(adc);
        const struct iio_chan_spec *chan;
        struct stm32_dfsdm_channel *ch;
        int i, ret;

        /* restore channels configuration */
        for (i = 0; i < indio_dev->num_channels; i++) {
                chan = indio_dev->channels + i;
                ch = &adc->dfsdm->ch_list[chan->channel];
                ret = stm32_dfsdm_chan_configure(adc->dfsdm, ch);
                if (ret)
                        return ret;
        }

        if (iio_buffer_enabled(indio_dev))
                __stm32_dfsdm_postenable(indio_dev);

        return 0;
}

static SIMPLE_DEV_PM_OPS(stm32_dfsdm_adc_pm_ops,
                         stm32_dfsdm_adc_suspend, stm32_dfsdm_adc_resume);

static struct platform_driver stm32_dfsdm_adc_driver = {
        .driver = {
                .name = "stm32-dfsdm-adc",
                .of_match_table = stm32_dfsdm_adc_match,
                .pm = &stm32_dfsdm_adc_pm_ops,
        },
        .probe = stm32_dfsdm_adc_probe,
        .remove = stm32_dfsdm_adc_remove,
};
module_platform_driver(stm32_dfsdm_adc_driver);

MODULE_DESCRIPTION("STM32 sigma delta ADC");
MODULE_AUTHOR("Arnaud Pouliquen <arnaud.pouliquen@st.com>");
MODULE_LICENSE("GPL v2");