// SPDX-License-Identifier: GPL-2.0-only
/*
 * sca3000_core.c -- support VTI sca3000 series accelerometers via SPI
 *
 * Copyright (c) 2009 Jonathan Cameron <jic23@kernel.org>
 *
 * See industrialio/accels/sca3000.h for comments.
 */

#include <linux/interrupt.h>
#include <linux/fs.h>
#include <linux/device.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/spi/spi.h>
#include <linux/sysfs.h>
#include <linux/module.h>
#include <linux/uaccess.h>
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/events.h>
#include <linux/iio/buffer.h>
#include <linux/iio/kfifo_buf.h>

#define SCA3000_WRITE_REG(a) (((a) << 2) | 0x02)
#define SCA3000_READ_REG(a) ((a) << 2)

#define SCA3000_REG_REVID_ADDR                          0x00
#define   SCA3000_REG_REVID_MAJOR_MASK                  GENMASK(8, 4)
#define   SCA3000_REG_REVID_MINOR_MASK                  GENMASK(3, 0)

#define SCA3000_REG_STATUS_ADDR                         0x02
#define   SCA3000_LOCKED                                BIT(5)
#define   SCA3000_EEPROM_CS_ERROR                       BIT(1)
#define   SCA3000_SPI_FRAME_ERROR                       BIT(0)

/* All reads done using register decrement so no need to directly access LSBs */
#define SCA3000_REG_X_MSB_ADDR                          0x05
#define SCA3000_REG_Y_MSB_ADDR                          0x07
#define SCA3000_REG_Z_MSB_ADDR                          0x09

#define SCA3000_REG_RING_OUT_ADDR                       0x0f

/* Temp read untested - the e05 doesn't have the sensor */
#define SCA3000_REG_TEMP_MSB_ADDR                       0x13

#define SCA3000_REG_MODE_ADDR                           0x14
#define SCA3000_MODE_PROT_MASK                          0x28
#define   SCA3000_REG_MODE_RING_BUF_ENABLE              BIT(7)
#define   SCA3000_REG_MODE_RING_BUF_8BIT                BIT(6)

/*
 * Free fall detection triggers an interrupt if the acceleration
 * is below a threshold for equivalent of 25cm drop
 */
#define   SCA3000_REG_MODE_FREE_FALL_DETECT             BIT(4)
#define   SCA3000_REG_MODE_MEAS_MODE_NORMAL             0x00
#define   SCA3000_REG_MODE_MEAS_MODE_OP_1               0x01
#define   SCA3000_REG_MODE_MEAS_MODE_OP_2               0x02

/*
 * In motion detection mode the accelerations are band pass filtered
 * (approx 1 - 25Hz) and then a programmable threshold used to trigger
 * and interrupt.
 */
#define   SCA3000_REG_MODE_MEAS_MODE_MOT_DET            0x03
#define   SCA3000_REG_MODE_MODE_MASK                    0x03

#define SCA3000_REG_BUF_COUNT_ADDR                      0x15

#define SCA3000_REG_INT_STATUS_ADDR                     0x16
#define   SCA3000_REG_INT_STATUS_THREE_QUARTERS         BIT(7)
#define   SCA3000_REG_INT_STATUS_HALF                   BIT(6)

#define SCA3000_INT_STATUS_FREE_FALL                    BIT(3)
#define SCA3000_INT_STATUS_Y_TRIGGER                    BIT(2)
#define SCA3000_INT_STATUS_X_TRIGGER                    BIT(1)
#define SCA3000_INT_STATUS_Z_TRIGGER                    BIT(0)

/* Used to allow access to multiplexed registers */
#define SCA3000_REG_CTRL_SEL_ADDR                       0x18
/* Only available for SCA3000-D03 and SCA3000-D01 */
#define   SCA3000_REG_CTRL_SEL_I2C_DISABLE              0x01
#define   SCA3000_REG_CTRL_SEL_MD_CTRL                  0x02
#define   SCA3000_REG_CTRL_SEL_MD_Y_TH                  0x03
#define   SCA3000_REG_CTRL_SEL_MD_X_TH                  0x04
#define   SCA3000_REG_CTRL_SEL_MD_Z_TH                  0x05
/*
 * BE VERY CAREFUL WITH THIS, IF 3 BITS ARE NOT SET the device
 * will not function
 */
#define   SCA3000_REG_CTRL_SEL_OUT_CTRL                 0x0B

#define     SCA3000_REG_OUT_CTRL_PROT_MASK              0xE0
#define     SCA3000_REG_OUT_CTRL_BUF_X_EN               0x10
#define     SCA3000_REG_OUT_CTRL_BUF_Y_EN               0x08
#define     SCA3000_REG_OUT_CTRL_BUF_Z_EN               0x04
#define     SCA3000_REG_OUT_CTRL_BUF_DIV_MASK           0x03
#define     SCA3000_REG_OUT_CTRL_BUF_DIV_4              0x02
#define     SCA3000_REG_OUT_CTRL_BUF_DIV_2              0x01


/*
 * Control which motion detector interrupts are on.
 * For now only OR combinations are supported.
 */
#define SCA3000_MD_CTRL_PROT_MASK                       0xC0
#define SCA3000_MD_CTRL_OR_Y                            BIT(0)
#define SCA3000_MD_CTRL_OR_X                            BIT(1)
#define SCA3000_MD_CTRL_OR_Z                            BIT(2)
/* Currently unsupported */
#define SCA3000_MD_CTRL_AND_Y                           BIT(3)
#define SCA3000_MD_CTRL_AND_X                           BIT(4)
#define SCA3000_MD_CTRL_AND_Z                           BIT(5)

/*
 * Some control registers of complex access methods requiring this register to
 * be used to remove a lock.
 */
#define SCA3000_REG_UNLOCK_ADDR                         0x1e

#define SCA3000_REG_INT_MASK_ADDR                       0x21
#define   SCA3000_REG_INT_MASK_PROT_MASK                0x1C

#define   SCA3000_REG_INT_MASK_RING_THREE_QUARTER       BIT(7)
#define   SCA3000_REG_INT_MASK_RING_HALF                BIT(6)

#define SCA3000_REG_INT_MASK_ALL_INTS                   0x02
#define SCA3000_REG_INT_MASK_ACTIVE_HIGH                0x01
#define SCA3000_REG_INT_MASK_ACTIVE_LOW                 0x00
/* Values of multiplexed registers (write to ctrl_data after select) */
#define SCA3000_REG_CTRL_DATA_ADDR                      0x22

/*
 * Measurement modes available on some sca3000 series chips. Code assumes others
 * may become available in the future.
 *
 * Bypass - Bypass the low-pass filter in the signal channel so as to increase
 *          signal bandwidth.
 *
 * Narrow - Narrow low-pass filtering of the signal channel and half output
 *          data rate by decimation.
 *
 * Wide - Widen low-pass filtering of signal channel to increase bandwidth
 */
#define SCA3000_OP_MODE_BYPASS                          0x01
#define SCA3000_OP_MODE_NARROW                          0x02
#define SCA3000_OP_MODE_WIDE                            0x04
#define SCA3000_MAX_TX 6
#define SCA3000_MAX_RX 2

/**
 * struct sca3000_state - device instance state information
 * @us:                 the associated spi device
 * @info:                       chip variant information
 * @mo_det_use_count:           reference counter for the motion detection unit
 * @lock:                       lock used to protect elements of sca3000_state
 *                              and the underlying device state.
 * @tx:                 dma-able transmit buffer
 * @rx:                 dma-able receive buffer
 **/
struct sca3000_state {
        struct spi_device               *us;
        const struct sca3000_chip_info  *info;
        int                             mo_det_use_count;
        struct mutex                    lock;
        /* Can these share a cacheline ? */
        u8                              rx[384] __aligned(IIO_DMA_MINALIGN);
        u8                              tx[6] __aligned(IIO_DMA_MINALIGN);
};

/**
 * struct sca3000_chip_info - model dependent parameters
 * @scale:                      scale * 10^-6
 * @temp_output:                some devices have temperature sensors.
 * @measurement_mode_freq:      normal mode sampling frequency
 * @measurement_mode_3db_freq:  3db cutoff frequency of the low pass filter for
 * the normal measurement mode.
 * @option_mode_1:              first optional mode. Not all models have one
 * @option_mode_1_freq:         option mode 1 sampling frequency
 * @option_mode_1_3db_freq:     3db cutoff frequency of the low pass filter for
 * the first option mode.
 * @option_mode_2:              second optional mode. Not all chips have one
 * @option_mode_2_freq:         option mode 2 sampling frequency
 * @option_mode_2_3db_freq:     3db cutoff frequency of the low pass filter for
 * the second option mode.
 * @mot_det_mult_xz:            Bit wise multipliers to calculate the threshold
 * for motion detection in the x and z axis.
 * @mot_det_mult_y:             Bit wise multipliers to calculate the threshold
 * for motion detection in the y axis.
 *
 * This structure is used to hold information about the functionality of a given
 * sca3000 variant.
 **/
struct sca3000_chip_info {
        unsigned int            scale;
        bool                    temp_output;
        int                     measurement_mode_freq;
        int                     measurement_mode_3db_freq;
        int                     option_mode_1;
        int                     option_mode_1_freq;
        int                     option_mode_1_3db_freq;
        int                     option_mode_2;
        int                     option_mode_2_freq;
        int                     option_mode_2_3db_freq;
        int                     mot_det_mult_xz[6];
        int                     mot_det_mult_y[7];
};

enum sca3000_variant {
        d01,
        e02,
        e04,
        e05,
};

/*
 * Note where option modes are not defined, the chip simply does not
 * support any.
 * Other chips in the sca3000 series use i2c and are not included here.
 *
 * Some of these devices are only listed in the family data sheet and
 * do not actually appear to be available.
 */
static const struct sca3000_chip_info sca3000_spi_chip_info_tbl[] = {
        [d01] = {
                .scale = 7357,
                .temp_output = true,
                .measurement_mode_freq = 250,
                .measurement_mode_3db_freq = 45,
                .option_mode_1 = SCA3000_OP_MODE_BYPASS,
                .option_mode_1_freq = 250,
                .option_mode_1_3db_freq = 70,
                .mot_det_mult_xz = {50, 100, 200, 350, 650, 1300},
                .mot_det_mult_y = {50, 100, 150, 250, 450, 850, 1750},
        },
        [e02] = {
                .scale = 9810,
                .measurement_mode_freq = 125,
                .measurement_mode_3db_freq = 40,
                .option_mode_1 = SCA3000_OP_MODE_NARROW,
                .option_mode_1_freq = 63,
                .option_mode_1_3db_freq = 11,
                .mot_det_mult_xz = {100, 150, 300, 550, 1050, 2050},
                .mot_det_mult_y = {50, 100, 200, 350, 700, 1350, 2700},
        },
        [e04] = {
                .scale = 19620,
                .measurement_mode_freq = 100,
                .measurement_mode_3db_freq = 38,
                .option_mode_1 = SCA3000_OP_MODE_NARROW,
                .option_mode_1_freq = 50,
                .option_mode_1_3db_freq = 9,
                .option_mode_2 = SCA3000_OP_MODE_WIDE,
                .option_mode_2_freq = 400,
                .option_mode_2_3db_freq = 70,
                .mot_det_mult_xz = {200, 300, 600, 1100, 2100, 4100},
                .mot_det_mult_y = {100, 200, 400, 7000, 1400, 2700, 54000},
        },
        [e05] = {
                .scale = 61313,
                .measurement_mode_freq = 200,
                .measurement_mode_3db_freq = 60,
                .option_mode_1 = SCA3000_OP_MODE_NARROW,
                .option_mode_1_freq = 50,
                .option_mode_1_3db_freq = 9,
                .option_mode_2 = SCA3000_OP_MODE_WIDE,
                .option_mode_2_freq = 400,
                .option_mode_2_3db_freq = 75,
                .mot_det_mult_xz = {600, 900, 1700, 3200, 6100, 11900},
                .mot_det_mult_y = {300, 600, 1200, 2000, 4100, 7800, 15600},
        },
};

static int sca3000_write_reg(struct sca3000_state *st, u8 address, u8 val)
{
        st->tx[0] = SCA3000_WRITE_REG(address);
        st->tx[1] = val;
        return spi_write(st->us, st->tx, 2);
}

static int sca3000_read_data_short(struct sca3000_state *st,
                                   u8 reg_address_high,
                                   int len)
{
        struct spi_transfer xfer[2] = {
                {
                        .len = 1,
                        .tx_buf = st->tx,
                }, {
                        .len = len,
                        .rx_buf = st->rx,
                }
        };
        st->tx[0] = SCA3000_READ_REG(reg_address_high);

        return spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
}

/**
 * sca3000_reg_lock_on() - test if the ctrl register lock is on
 * @st: Driver specific device instance data.
 *
 * Lock must be held.
 **/
static int sca3000_reg_lock_on(struct sca3000_state *st)
{
        int ret;

        ret = sca3000_read_data_short(st, SCA3000_REG_STATUS_ADDR, 1);
        if (ret < 0)
                return ret;

        return !(st->rx[0] & SCA3000_LOCKED);
}

/**
 * __sca3000_unlock_reg_lock() - unlock the control registers
 * @st: Driver specific device instance data.
 *
 * Note the device does not appear to support doing this in a single transfer.
 * This should only ever be used as part of ctrl reg read.
 * Lock must be held before calling this
 */
static int __sca3000_unlock_reg_lock(struct sca3000_state *st)
{
        struct spi_transfer xfer[3] = {
                {
                        .len = 2,
                        .cs_change = 1,
                        .tx_buf = st->tx,
                }, {
                        .len = 2,
                        .cs_change = 1,
                        .tx_buf = st->tx + 2,
                }, {
                        .len = 2,
                        .tx_buf = st->tx + 4,
                },
        };
        st->tx[0] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);
        st->tx[1] = 0x00;
        st->tx[2] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);
        st->tx[3] = 0x50;
        st->tx[4] = SCA3000_WRITE_REG(SCA3000_REG_UNLOCK_ADDR);
        st->tx[5] = 0xA0;

        return spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
}

/**
 * sca3000_write_ctrl_reg() - write to a lock protect ctrl register
 * @st: Driver specific device instance data.
 * @sel: selects which registers we wish to write to
 * @val: the value to be written
 *
 * Certain control registers are protected against overwriting by the lock
 * register and use a shared write address. This function allows writing of
 * these registers.
 * Lock must be held.
 */
static int sca3000_write_ctrl_reg(struct sca3000_state *st,
                                  u8 sel,
                                  uint8_t val)
{
        int ret;

        ret = sca3000_reg_lock_on(st);
        if (ret < 0)
                return ret;
        if (ret) {
                ret = __sca3000_unlock_reg_lock(st);
                if (ret)
                        return ret;
        }

        /* Set the control select register */
        ret = sca3000_write_reg(st, SCA3000_REG_CTRL_SEL_ADDR, sel);
        if (ret)
                return ret;

        /* Write the actual value into the register */
        return sca3000_write_reg(st, SCA3000_REG_CTRL_DATA_ADDR, val);
}

/**
 * sca3000_read_ctrl_reg() - read from lock protected control register.
 * @st: Driver specific device instance data.
 * @ctrl_reg: Which ctrl register do we want to read.
 *
 * Lock must be held.
 */
static int sca3000_read_ctrl_reg(struct sca3000_state *st,
                                 u8 ctrl_reg)
{
        int ret;

        ret = sca3000_reg_lock_on(st);
        if (ret < 0)
                return ret;
        if (ret) {
                ret = __sca3000_unlock_reg_lock(st);
                if (ret)
                        return ret;
        }
        /* Set the control select register */
        ret = sca3000_write_reg(st, SCA3000_REG_CTRL_SEL_ADDR, ctrl_reg);
        if (ret)
                return ret;
        ret = sca3000_read_data_short(st, SCA3000_REG_CTRL_DATA_ADDR, 1);
        if (ret)
                return ret;
        return st->rx[0];
}

/**
 * sca3000_print_rev() - sysfs interface to read the chip revision number
 * @indio_dev: Device instance specific generic IIO data.
 * Driver specific device instance data can be obtained via
 * iio_priv(indio_dev)
 */
static int sca3000_print_rev(struct iio_dev *indio_dev)
{
        int ret;
        struct sca3000_state *st = iio_priv(indio_dev);

        mutex_lock(&st->lock);
        ret = sca3000_read_data_short(st, SCA3000_REG_REVID_ADDR, 1);
        if (ret < 0)
                goto error_ret;
        dev_info(&indio_dev->dev,
                 "sca3000 revision major=%lu, minor=%lu\n",
                 st->rx[0] & SCA3000_REG_REVID_MAJOR_MASK,
                 st->rx[0] & SCA3000_REG_REVID_MINOR_MASK);
error_ret:
        mutex_unlock(&st->lock);

        return ret;
}

static ssize_t
sca3000_show_available_3db_freqs(struct device *dev,
                                 struct device_attribute *attr,
                                 char *buf)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        struct sca3000_state *st = iio_priv(indio_dev);
        int len;

        len = sprintf(buf, "%d", st->info->measurement_mode_3db_freq);
        if (st->info->option_mode_1)
                len += sprintf(buf + len, " %d",
                               st->info->option_mode_1_3db_freq);
        if (st->info->option_mode_2)
                len += sprintf(buf + len, " %d",
                               st->info->option_mode_2_3db_freq);
        len += sprintf(buf + len, "\n");

        return len;
}

static IIO_DEVICE_ATTR(in_accel_filter_low_pass_3db_frequency_available,
                       S_IRUGO, sca3000_show_available_3db_freqs,
                       NULL, 0);

static const struct iio_event_spec sca3000_event = {
        .type = IIO_EV_TYPE_MAG,
        .dir = IIO_EV_DIR_RISING,
        .mask_separate = BIT(IIO_EV_INFO_VALUE) | BIT(IIO_EV_INFO_ENABLE),
};

/*
 * Note the hack in the number of bits to pretend we have 2 more than
 * we do in the fifo.
 */
#define SCA3000_CHAN(index, mod)                                \
        {                                                       \
                .type = IIO_ACCEL,                              \
                .modified = 1,                                  \
                .channel2 = mod,                                \
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),   \
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |\
                        BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY),\
                .info_mask_shared_by_all = BIT(IIO_CHAN_INFO_SAMP_FREQ),\
                .address = index,                               \
                .scan_index = index,                            \
                .scan_type = {                                  \
                        .sign = 's',                            \
                        .realbits = 13,                         \
                        .storagebits = 16,                      \
                        .shift = 3,                             \
                        .endianness = IIO_BE,                   \
                },                                              \
                .event_spec = &sca3000_event,                   \
                .num_event_specs = 1,                           \
        }

static const struct iio_event_spec sca3000_freefall_event_spec = {
        .type = IIO_EV_TYPE_MAG,
        .dir = IIO_EV_DIR_FALLING,
        .mask_separate = BIT(IIO_EV_INFO_ENABLE) |
                BIT(IIO_EV_INFO_PERIOD),
};

static const struct iio_chan_spec sca3000_channels[] = {
        SCA3000_CHAN(0, IIO_MOD_X),
        SCA3000_CHAN(1, IIO_MOD_Y),
        SCA3000_CHAN(2, IIO_MOD_Z),
        {
                .type = IIO_ACCEL,
                .modified = 1,
                .channel2 = IIO_MOD_X_AND_Y_AND_Z,
                .scan_index = -1, /* Fake channel */
                .event_spec = &sca3000_freefall_event_spec,
                .num_event_specs = 1,
        },
};

static const struct iio_chan_spec sca3000_channels_with_temp[] = {
        SCA3000_CHAN(0, IIO_MOD_X),
        SCA3000_CHAN(1, IIO_MOD_Y),
        SCA3000_CHAN(2, IIO_MOD_Z),
        {
                .type = IIO_TEMP,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE) |
                        BIT(IIO_CHAN_INFO_OFFSET),
                /* No buffer support */
                .scan_index = -1,
                .scan_type = {
                        .sign = 'u',
                        .realbits = 9,
                        .storagebits = 16,
                        .shift = 5,
                        .endianness = IIO_BE,
                },
        },
        {
                .type = IIO_ACCEL,
                .modified = 1,
                .channel2 = IIO_MOD_X_AND_Y_AND_Z,
                .scan_index = -1, /* Fake channel */
                .event_spec = &sca3000_freefall_event_spec,
                .num_event_specs = 1,
        },
};

static u8 sca3000_addresses[3][3] = {
        [0] = {SCA3000_REG_X_MSB_ADDR, SCA3000_REG_CTRL_SEL_MD_X_TH,
               SCA3000_MD_CTRL_OR_X},
        [1] = {SCA3000_REG_Y_MSB_ADDR, SCA3000_REG_CTRL_SEL_MD_Y_TH,
               SCA3000_MD_CTRL_OR_Y},
        [2] = {SCA3000_REG_Z_MSB_ADDR, SCA3000_REG_CTRL_SEL_MD_Z_TH,
               SCA3000_MD_CTRL_OR_Z},
};

/**
 * __sca3000_get_base_freq() - obtain mode specific base frequency
 * @st: Private driver specific device instance specific state.
 * @info: chip type specific information.
 * @base_freq: Base frequency for the current measurement mode.
 *
 * lock must be held
 */
static inline int __sca3000_get_base_freq(struct sca3000_state *st,
                                          const struct sca3000_chip_info *info,
                                          int *base_freq)
{
        int ret;

        ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
        if (ret)
                return ret;

        switch (SCA3000_REG_MODE_MODE_MASK & st->rx[0]) {
        case SCA3000_REG_MODE_MEAS_MODE_NORMAL:
                *base_freq = info->measurement_mode_freq;
                break;
        case SCA3000_REG_MODE_MEAS_MODE_OP_1:
                *base_freq = info->option_mode_1_freq;
                break;
        case SCA3000_REG_MODE_MEAS_MODE_OP_2:
                *base_freq = info->option_mode_2_freq;
                break;
        default:
                ret = -EINVAL;
        }
        return ret;
}

/**
 * sca3000_read_raw_samp_freq() - read_raw handler for IIO_CHAN_INFO_SAMP_FREQ
 * @st: Private driver specific device instance specific state.
 * @val: The frequency read back.
 *
 * lock must be held
 **/
static int sca3000_read_raw_samp_freq(struct sca3000_state *st, int *val)
{
        int ret;

        ret = __sca3000_get_base_freq(st, st->info, val);
        if (ret)
                return ret;

        ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL);
        if (ret < 0)
                return ret;

        if (*val > 0) {
                ret &= SCA3000_REG_OUT_CTRL_BUF_DIV_MASK;
                switch (ret) {
                case SCA3000_REG_OUT_CTRL_BUF_DIV_2:
                        *val /= 2;
                        break;
                case SCA3000_REG_OUT_CTRL_BUF_DIV_4:
                        *val /= 4;
                        break;
                }
        }

        return 0;
}

/**
 * sca3000_write_raw_samp_freq() - write_raw handler for IIO_CHAN_INFO_SAMP_FREQ
 * @st: Private driver specific device instance specific state.
 * @val: The frequency desired.
 *
 * lock must be held
 */
static int sca3000_write_raw_samp_freq(struct sca3000_state *st, int val)
{
        int ret, base_freq, ctrlval;

        ret = __sca3000_get_base_freq(st, st->info, &base_freq);
        if (ret)
                return ret;

        ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL);
        if (ret < 0)
                return ret;

        ctrlval = ret & ~SCA3000_REG_OUT_CTRL_BUF_DIV_MASK;

        if (val == base_freq / 2)
                ctrlval |= SCA3000_REG_OUT_CTRL_BUF_DIV_2;
        if (val == base_freq / 4)
                ctrlval |= SCA3000_REG_OUT_CTRL_BUF_DIV_4;
        else if (val != base_freq)
                return -EINVAL;

        return sca3000_write_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL,
                                     ctrlval);
}

static int sca3000_read_3db_freq(struct sca3000_state *st, int *val)
{
        int ret;

        ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
        if (ret)
                return ret;

        /* mask bottom 2 bits - only ones that are relevant */
        st->rx[0] &= SCA3000_REG_MODE_MODE_MASK;
        switch (st->rx[0]) {
        case SCA3000_REG_MODE_MEAS_MODE_NORMAL:
                *val = st->info->measurement_mode_3db_freq;
                return IIO_VAL_INT;
        case SCA3000_REG_MODE_MEAS_MODE_MOT_DET:
                return -EBUSY;
        case SCA3000_REG_MODE_MEAS_MODE_OP_1:
                *val = st->info->option_mode_1_3db_freq;
                return IIO_VAL_INT;
        case SCA3000_REG_MODE_MEAS_MODE_OP_2:
                *val = st->info->option_mode_2_3db_freq;
                return IIO_VAL_INT;
        default:
                return -EINVAL;
        }
}

static int sca3000_write_3db_freq(struct sca3000_state *st, int val)
{
        int ret;
        int mode;

        if (val == st->info->measurement_mode_3db_freq)
                mode = SCA3000_REG_MODE_MEAS_MODE_NORMAL;
        else if (st->info->option_mode_1 &&
                 (val == st->info->option_mode_1_3db_freq))
                mode = SCA3000_REG_MODE_MEAS_MODE_OP_1;
        else if (st->info->option_mode_2 &&
                 (val == st->info->option_mode_2_3db_freq))
                mode = SCA3000_REG_MODE_MEAS_MODE_OP_2;
        else
                return -EINVAL;
        ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
        if (ret)
                return ret;

        st->rx[0] &= ~SCA3000_REG_MODE_MODE_MASK;
        st->rx[0] |= (mode & SCA3000_REG_MODE_MODE_MASK);

        return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR, st->rx[0]);
}

static int sca3000_read_raw(struct iio_dev *indio_dev,
                            struct iio_chan_spec const *chan,
                            int *val,
                            int *val2,
                            long mask)
{
        struct sca3000_state *st = iio_priv(indio_dev);
        int ret;
        u8 address;

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                mutex_lock(&st->lock);
                if (chan->type == IIO_ACCEL) {
                        if (st->mo_det_use_count) {
                                mutex_unlock(&st->lock);
                                return -EBUSY;
                        }
                        address = sca3000_addresses[chan->address][0];
                        ret = sca3000_read_data_short(st, address, 2);
                        if (ret < 0) {
                                mutex_unlock(&st->lock);
                                return ret;
                        }
                        *val = sign_extend32(be16_to_cpup((__be16 *)st->rx) >>
                                             chan->scan_type.shift,
                                             chan->scan_type.realbits - 1);
                } else {
                        /* get the temperature when available */
                        ret = sca3000_read_data_short(st,
                                                      SCA3000_REG_TEMP_MSB_ADDR,
                                                      2);
                        if (ret < 0) {
                                mutex_unlock(&st->lock);
                                return ret;
                        }
                        *val = (be16_to_cpup((__be16 *)st->rx) >>
                                chan->scan_type.shift) &
                                GENMASK(chan->scan_type.realbits - 1, 0);
                }
                mutex_unlock(&st->lock);
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
                *val = 0;
                if (chan->type == IIO_ACCEL)
                        *val2 = st->info->scale;
                else /* temperature */
                        *val2 = 555556;
                return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_OFFSET:
                *val = -214;
                *val2 = 600000;
                return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_SAMP_FREQ:
                mutex_lock(&st->lock);
                ret = sca3000_read_raw_samp_freq(st, val);
                mutex_unlock(&st->lock);
                return ret ? ret : IIO_VAL_INT;
        case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
                mutex_lock(&st->lock);
                ret = sca3000_read_3db_freq(st, val);
                mutex_unlock(&st->lock);
                return ret;
        default:
                return -EINVAL;
        }
}

static int sca3000_write_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int val, int val2, long mask)
{
        struct sca3000_state *st = iio_priv(indio_dev);
        int ret;

        switch (mask) {
        case IIO_CHAN_INFO_SAMP_FREQ:
                if (val2)
                        return -EINVAL;
                mutex_lock(&st->lock);
                ret = sca3000_write_raw_samp_freq(st, val);
                mutex_unlock(&st->lock);
                return ret;
        case IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY:
                if (val2)
                        return -EINVAL;
                mutex_lock(&st->lock);
                ret = sca3000_write_3db_freq(st, val);
                mutex_unlock(&st->lock);
                return ret;
        default:
                return -EINVAL;
        }

        return ret;
}

/**
 * sca3000_read_av_freq() - sysfs function to get available frequencies
 * @dev: Device structure for this device.
 * @attr: Description of the attribute.
 * @buf: Incoming string
 *
 * The later modes are only relevant to the ring buffer - and depend on current
 * mode. Note that data sheet gives rather wide tolerances for these so integer
 * division will give good enough answer and not all chips have them specified
 * at all.
 **/
static ssize_t sca3000_read_av_freq(struct device *dev,
                                    struct device_attribute *attr,
                                    char *buf)
{
        struct iio_dev *indio_dev = dev_to_iio_dev(dev);
        struct sca3000_state *st = iio_priv(indio_dev);
        int len = 0, ret, val;

        mutex_lock(&st->lock);
        ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
        val = st->rx[0];
        mutex_unlock(&st->lock);
        if (ret)
                return ret;

        switch (val & SCA3000_REG_MODE_MODE_MASK) {
        case SCA3000_REG_MODE_MEAS_MODE_NORMAL:
                len += sprintf(buf + len, "%d %d %d\n",
                               st->info->measurement_mode_freq,
                               st->info->measurement_mode_freq / 2,
                               st->info->measurement_mode_freq / 4);
                break;
        case SCA3000_REG_MODE_MEAS_MODE_OP_1:
                len += sprintf(buf + len, "%d %d %d\n",
                               st->info->option_mode_1_freq,
                               st->info->option_mode_1_freq / 2,
                               st->info->option_mode_1_freq / 4);
                break;
        case SCA3000_REG_MODE_MEAS_MODE_OP_2:
                len += sprintf(buf + len, "%d %d %d\n",
                               st->info->option_mode_2_freq,
                               st->info->option_mode_2_freq / 2,
                               st->info->option_mode_2_freq / 4);
                break;
        }
        return len;
}

/*
 * Should only really be registered if ring buffer support is compiled in.
 * Does no harm however and doing it right would add a fair bit of complexity
 */
static IIO_DEV_ATTR_SAMP_FREQ_AVAIL(sca3000_read_av_freq);

/*
 * sca3000_read_event_value() - query of a threshold or period
 */
static int sca3000_read_event_value(struct iio_dev *indio_dev,
                                    const struct iio_chan_spec *chan,
                                    enum iio_event_type type,
                                    enum iio_event_direction dir,
                                    enum iio_event_info info,
                                    int *val, int *val2)
{
        struct sca3000_state *st = iio_priv(indio_dev);
        long ret;
        int i;

        switch (info) {
        case IIO_EV_INFO_VALUE:
                mutex_lock(&st->lock);
                ret = sca3000_read_ctrl_reg(st,
                                            sca3000_addresses[chan->address][1]);
                mutex_unlock(&st->lock);
                if (ret < 0)
                        return ret;
                *val = 0;
                if (chan->channel2 == IIO_MOD_Y)
                        for_each_set_bit(i, &ret,
                                         ARRAY_SIZE(st->info->mot_det_mult_y))
                                *val += st->info->mot_det_mult_y[i];
                else
                        for_each_set_bit(i, &ret,
                                         ARRAY_SIZE(st->info->mot_det_mult_xz))
                                *val += st->info->mot_det_mult_xz[i];

                return IIO_VAL_INT;
        case IIO_EV_INFO_PERIOD:
                *val = 0;
                *val2 = 226000;
                return IIO_VAL_INT_PLUS_MICRO;
        default:
                return -EINVAL;
        }
}

/**
 * sca3000_write_event_value() - control of threshold and period
 * @indio_dev: Device instance specific IIO information.
 * @chan: Description of the channel for which the event is being
 * configured.
 * @type: The type of event being configured, here magnitude rising
 * as everything else is read only.
 * @dir: Direction of the event (here rising)
 * @info: What information about the event are we configuring.
 * Here the threshold only.
 * @val: Integer part of the value being written..
 * @val2: Non integer part of the value being written. Here always 0.
 */
static int sca3000_write_event_value(struct iio_dev *indio_dev,
                                     const struct iio_chan_spec *chan,
                                     enum iio_event_type type,
                                     enum iio_event_direction dir,
                                     enum iio_event_info info,
                                     int val, int val2)
{
        struct sca3000_state *st = iio_priv(indio_dev);
        int ret;
        int i;
        u8 nonlinear = 0;

        if (chan->channel2 == IIO_MOD_Y) {
                i = ARRAY_SIZE(st->info->mot_det_mult_y);
                while (i > 0)
                        if (val >= st->info->mot_det_mult_y[--i]) {
                                nonlinear |= (1 << i);
                                val -= st->info->mot_det_mult_y[i];
                        }
        } else {
                i = ARRAY_SIZE(st->info->mot_det_mult_xz);
                while (i > 0)
                        if (val >= st->info->mot_det_mult_xz[--i]) {
                                nonlinear |= (1 << i);
                                val -= st->info->mot_det_mult_xz[i];
                        }
        }

        mutex_lock(&st->lock);
        ret = sca3000_write_ctrl_reg(st,
                                     sca3000_addresses[chan->address][1],
                                     nonlinear);
        mutex_unlock(&st->lock);

        return ret;
}

static struct attribute *sca3000_attributes[] = {
        &iio_dev_attr_in_accel_filter_low_pass_3db_frequency_available.dev_attr.attr,
        &iio_dev_attr_sampling_frequency_available.dev_attr.attr,
        NULL,
};

static const struct attribute_group sca3000_attribute_group = {
        .attrs = sca3000_attributes,
};

static int sca3000_read_data(struct sca3000_state *st,
                             u8 reg_address_high,
                             u8 *rx,
                             int len)
{
        int ret;
        struct spi_transfer xfer[2] = {
                {
                        .len = 1,
                        .tx_buf = st->tx,
                }, {
                        .len = len,
                        .rx_buf = rx,
                }
        };

        st->tx[0] = SCA3000_READ_REG(reg_address_high);
        ret = spi_sync_transfer(st->us, xfer, ARRAY_SIZE(xfer));
        if (ret) {
                dev_err(&st->us->dev, "problem reading register\n");
                return ret;
        }

        return 0;
}

/**
 * sca3000_ring_int_process() - ring specific interrupt handling.
 * @val: Value of the interrupt status register.
 * @indio_dev: Device instance specific IIO device structure.
 */
static void sca3000_ring_int_process(u8 val, struct iio_dev *indio_dev)
{
        struct sca3000_state *st = iio_priv(indio_dev);
        int ret, i, num_available;

        mutex_lock(&st->lock);

        if (val & SCA3000_REG_INT_STATUS_HALF) {
                ret = sca3000_read_data_short(st, SCA3000_REG_BUF_COUNT_ADDR,
                                              1);
                if (ret)
                        goto error_ret;
                num_available = st->rx[0];
                /*
                 * num_available is the total number of samples available
                 * i.e. number of time points * number of channels.
                 */
                ret = sca3000_read_data(st, SCA3000_REG_RING_OUT_ADDR, st->rx,
                                        num_available * 2);
                if (ret)
                        goto error_ret;
                for (i = 0; i < num_available / 3; i++) {
                        /*
                         * Dirty hack to cover for 11 bit in fifo, 13 bit
                         * direct reading.
                         *
                         * In theory the bottom two bits are undefined.
                         * In reality they appear to always be 0.
                         */
                        iio_push_to_buffers(indio_dev, st->rx + i * 3 * 2);
                }
        }
error_ret:
        mutex_unlock(&st->lock);
}

/**
 * sca3000_event_handler() - handling ring and non ring events
 * @irq: The irq being handled.
 * @private: struct iio_device pointer for the device.
 *
 * Ring related interrupt handler. Depending on event, push to
 * the ring buffer event chrdev or the event one.
 *
 * This function is complicated by the fact that the devices can signify ring
 * and non ring events via the same interrupt line and they can only
 * be distinguished via a read of the relevant status register.
 */
static irqreturn_t sca3000_event_handler(int irq, void *private)
{
        struct iio_dev *indio_dev = private;
        struct sca3000_state *st = iio_priv(indio_dev);
        int ret, val;
        s64 last_timestamp = iio_get_time_ns(indio_dev);

        /*
         * Could lead if badly timed to an extra read of status reg,
         * but ensures no interrupt is missed.
         */
        mutex_lock(&st->lock);
        ret = sca3000_read_data_short(st, SCA3000_REG_INT_STATUS_ADDR, 1);
        val = st->rx[0];
        mutex_unlock(&st->lock);
        if (ret)
                goto done;

        sca3000_ring_int_process(val, indio_dev);

        if (val & SCA3000_INT_STATUS_FREE_FALL)
                iio_push_event(indio_dev,
                               IIO_MOD_EVENT_CODE(IIO_ACCEL,
                                                  0,
                                                  IIO_MOD_X_AND_Y_AND_Z,
                                                  IIO_EV_TYPE_MAG,
                                                  IIO_EV_DIR_FALLING),
                               last_timestamp);

        if (val & SCA3000_INT_STATUS_Y_TRIGGER)
                iio_push_event(indio_dev,
                               IIO_MOD_EVENT_CODE(IIO_ACCEL,
                                                  0,
                                                  IIO_MOD_Y,
                                                  IIO_EV_TYPE_MAG,
                                                  IIO_EV_DIR_RISING),
                               last_timestamp);

        if (val & SCA3000_INT_STATUS_X_TRIGGER)
                iio_push_event(indio_dev,
                               IIO_MOD_EVENT_CODE(IIO_ACCEL,
                                                  0,
                                                  IIO_MOD_X,
                                                  IIO_EV_TYPE_MAG,
                                                  IIO_EV_DIR_RISING),
                               last_timestamp);

        if (val & SCA3000_INT_STATUS_Z_TRIGGER)
                iio_push_event(indio_dev,
                               IIO_MOD_EVENT_CODE(IIO_ACCEL,
                                                  0,
                                                  IIO_MOD_Z,
                                                  IIO_EV_TYPE_MAG,
                                                  IIO_EV_DIR_RISING),
                               last_timestamp);

done:
        return IRQ_HANDLED;
}

/*
 * sca3000_read_event_config() what events are enabled
 */
static int sca3000_read_event_config(struct iio_dev *indio_dev,
                                     const struct iio_chan_spec *chan,
                                     enum iio_event_type type,
                                     enum iio_event_direction dir)
{
        struct sca3000_state *st = iio_priv(indio_dev);
        int ret;
        /* read current value of mode register */
        mutex_lock(&st->lock);

        ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
        if (ret)
                goto error_ret;

        switch (chan->channel2) {
        case IIO_MOD_X_AND_Y_AND_Z:
                ret = !!(st->rx[0] & SCA3000_REG_MODE_FREE_FALL_DETECT);
                break;
        case IIO_MOD_X:
        case IIO_MOD_Y:
        case IIO_MOD_Z:
                /*
                 * Motion detection mode cannot run at the same time as
                 * acceleration data being read.
                 */
                if ((st->rx[0] & SCA3000_REG_MODE_MODE_MASK)
                    != SCA3000_REG_MODE_MEAS_MODE_MOT_DET) {
                        ret = 0;
                } else {
                        ret = sca3000_read_ctrl_reg(st,
                                                SCA3000_REG_CTRL_SEL_MD_CTRL);
                        if (ret < 0)
                                goto error_ret;
                        /* only supporting logical or's for now */
                        ret = !!(ret & sca3000_addresses[chan->address][2]);
                }
                break;
        default:
                ret = -EINVAL;
        }

error_ret:
        mutex_unlock(&st->lock);

        return ret;
}

static int sca3000_freefall_set_state(struct iio_dev *indio_dev, bool state)
{
        struct sca3000_state *st = iio_priv(indio_dev);
        int ret;

        /* read current value of mode register */
        ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
        if (ret)
                return ret;

        /* if off and should be on */
        if (state && !(st->rx[0] & SCA3000_REG_MODE_FREE_FALL_DETECT))
                return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
                                         st->rx[0] | SCA3000_REG_MODE_FREE_FALL_DETECT);
        /* if on and should be off */
        else if (!state && (st->rx[0] & SCA3000_REG_MODE_FREE_FALL_DETECT))
                return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
                                         st->rx[0] & ~SCA3000_REG_MODE_FREE_FALL_DETECT);
        else
                return 0;
}

static int sca3000_motion_detect_set_state(struct iio_dev *indio_dev, int axis,
                                           bool state)
{
        struct sca3000_state *st = iio_priv(indio_dev);
        int ret, ctrlval;

        /*
         * First read the motion detector config to find out if
         * this axis is on
         */
        ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_MD_CTRL);
        if (ret < 0)
                return ret;
        ctrlval = ret;
        /* if off and should be on */
        if (state && !(ctrlval & sca3000_addresses[axis][2])) {
                ret = sca3000_write_ctrl_reg(st,
                                             SCA3000_REG_CTRL_SEL_MD_CTRL,
                                             ctrlval |
                                             sca3000_addresses[axis][2]);
                if (ret)
                        return ret;
                st->mo_det_use_count++;
        } else if (!state && (ctrlval & sca3000_addresses[axis][2])) {
                ret = sca3000_write_ctrl_reg(st,
                                             SCA3000_REG_CTRL_SEL_MD_CTRL,
                                             ctrlval &
                                             ~(sca3000_addresses[axis][2]));
                if (ret)
                        return ret;
                st->mo_det_use_count--;
        }

        /* read current value of mode register */
        ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
        if (ret)
                return ret;
        /* if off and should be on */
        if ((st->mo_det_use_count) &&
            ((st->rx[0] & SCA3000_REG_MODE_MODE_MASK)
             != SCA3000_REG_MODE_MEAS_MODE_MOT_DET))
                return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
                        (st->rx[0] & ~SCA3000_REG_MODE_MODE_MASK)
                        | SCA3000_REG_MODE_MEAS_MODE_MOT_DET);
        /* if on and should be off */
        else if (!(st->mo_det_use_count) &&
                 ((st->rx[0] & SCA3000_REG_MODE_MODE_MASK)
                  == SCA3000_REG_MODE_MEAS_MODE_MOT_DET))
                return sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
                        st->rx[0] & SCA3000_REG_MODE_MODE_MASK);
        else
                return 0;
}

/**
 * sca3000_write_event_config() - simple on off control for motion detector
 * @indio_dev: IIO device instance specific structure. Data specific to this
 * particular driver may be accessed via iio_priv(indio_dev).
 * @chan: Description of the channel whose event we are configuring.
 * @type: The type of event.
 * @dir: The direction of the event.
 * @state: Desired state of event being configured.
 *
 * This is a per axis control, but enabling any will result in the
 * motion detector unit being enabled.
 * N.B. enabling motion detector stops normal data acquisition.
 * There is a complexity in knowing which mode to return to when
 * this mode is disabled.  Currently normal mode is assumed.
 **/
static int sca3000_write_event_config(struct iio_dev *indio_dev,
                                      const struct iio_chan_spec *chan,
                                      enum iio_event_type type,
                                      enum iio_event_direction dir,
                                      bool state)
{
        struct sca3000_state *st = iio_priv(indio_dev);
        int ret;

        mutex_lock(&st->lock);
        switch (chan->channel2) {
        case IIO_MOD_X_AND_Y_AND_Z:
                ret = sca3000_freefall_set_state(indio_dev, state);
                break;

        case IIO_MOD_X:
        case IIO_MOD_Y:
        case IIO_MOD_Z:
                ret = sca3000_motion_detect_set_state(indio_dev,
                                                      chan->address,
                                                      state);
                break;
        default:
                ret = -EINVAL;
                break;
        }
        mutex_unlock(&st->lock);

        return ret;
}

static inline
int __sca3000_hw_ring_state_set(struct iio_dev *indio_dev, bool state)
{
        struct sca3000_state *st = iio_priv(indio_dev);
        int ret;

        mutex_lock(&st->lock);
        ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
        if (ret)
                goto error_ret;
        if (state) {
                dev_info(&indio_dev->dev, "supposedly enabling ring buffer\n");
                ret = sca3000_write_reg(st,
                        SCA3000_REG_MODE_ADDR,
                        (st->rx[0] | SCA3000_REG_MODE_RING_BUF_ENABLE));
        } else
                ret = sca3000_write_reg(st,
                        SCA3000_REG_MODE_ADDR,
                        (st->rx[0] & ~SCA3000_REG_MODE_RING_BUF_ENABLE));
error_ret:
        mutex_unlock(&st->lock);

        return ret;
}

/**
 * sca3000_hw_ring_preenable() - hw ring buffer preenable function
 * @indio_dev: structure representing the IIO device. Device instance
 * specific state can be accessed via iio_priv(indio_dev).
 *
 * Very simple enable function as the chip will allows normal reads
 * during ring buffer operation so as long as it is indeed running
 * before we notify the core, the precise ordering does not matter.
 */
static int sca3000_hw_ring_preenable(struct iio_dev *indio_dev)
{
        int ret;
        struct sca3000_state *st = iio_priv(indio_dev);

        mutex_lock(&st->lock);

        /* Enable the 50% full interrupt */
        ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
        if (ret)
                goto error_unlock;
        ret = sca3000_write_reg(st,
                                SCA3000_REG_INT_MASK_ADDR,
                                st->rx[0] | SCA3000_REG_INT_MASK_RING_HALF);
        if (ret)
                goto error_unlock;

        mutex_unlock(&st->lock);

        return __sca3000_hw_ring_state_set(indio_dev, 1);

error_unlock:
        mutex_unlock(&st->lock);

        return ret;
}

static int sca3000_hw_ring_postdisable(struct iio_dev *indio_dev)
{
        int ret;
        struct sca3000_state *st = iio_priv(indio_dev);

        ret = __sca3000_hw_ring_state_set(indio_dev, 0);
        if (ret)
                return ret;

        /* Disable the 50% full interrupt */
        mutex_lock(&st->lock);

        ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
        if (ret)
                goto unlock;
        ret = sca3000_write_reg(st,
                                SCA3000_REG_INT_MASK_ADDR,
                                st->rx[0] & ~SCA3000_REG_INT_MASK_RING_HALF);
unlock:
        mutex_unlock(&st->lock);
        return ret;
}

static const struct iio_buffer_setup_ops sca3000_ring_setup_ops = {
        .preenable = &sca3000_hw_ring_preenable,
        .postdisable = &sca3000_hw_ring_postdisable,
};

/**
 * sca3000_clean_setup() - get the device into a predictable state
 * @st: Device instance specific private data structure
 *
 * Devices use flash memory to store many of the register values
 * and hence can come up in somewhat unpredictable states.
 * Hence reset everything on driver load.
 */
static int sca3000_clean_setup(struct sca3000_state *st)
{
        int ret;

        mutex_lock(&st->lock);
        /* Ensure all interrupts have been acknowledged */
        ret = sca3000_read_data_short(st, SCA3000_REG_INT_STATUS_ADDR, 1);
        if (ret)
                goto error_ret;

        /* Turn off all motion detection channels */
        ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_MD_CTRL);
        if (ret < 0)
                goto error_ret;
        ret = sca3000_write_ctrl_reg(st, SCA3000_REG_CTRL_SEL_MD_CTRL,
                                     ret & SCA3000_MD_CTRL_PROT_MASK);
        if (ret)
                goto error_ret;

        /* Disable ring buffer */
        ret = sca3000_read_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL);
        if (ret < 0)
                goto error_ret;
        ret = sca3000_write_ctrl_reg(st, SCA3000_REG_CTRL_SEL_OUT_CTRL,
                                     (ret & SCA3000_REG_OUT_CTRL_PROT_MASK)
                                     | SCA3000_REG_OUT_CTRL_BUF_X_EN
                                     | SCA3000_REG_OUT_CTRL_BUF_Y_EN
                                     | SCA3000_REG_OUT_CTRL_BUF_Z_EN
                                     | SCA3000_REG_OUT_CTRL_BUF_DIV_4);
        if (ret)
                goto error_ret;
        /* Enable interrupts, relevant to mode and set up as active low */
        ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
        if (ret)
                goto error_ret;
        ret = sca3000_write_reg(st,
                                SCA3000_REG_INT_MASK_ADDR,
                                (ret & SCA3000_REG_INT_MASK_PROT_MASK)
                                | SCA3000_REG_INT_MASK_ACTIVE_LOW);
        if (ret)
                goto error_ret;
        /*
         * Select normal measurement mode, free fall off, ring off
         * Ring in 12 bit mode - it is fine to overwrite reserved bits 3,5
         * as that occurs in one of the example on the datasheet
         */
        ret = sca3000_read_data_short(st, SCA3000_REG_MODE_ADDR, 1);
        if (ret)
                goto error_ret;
        ret = sca3000_write_reg(st, SCA3000_REG_MODE_ADDR,
                                (st->rx[0] & SCA3000_MODE_PROT_MASK));

error_ret:
        mutex_unlock(&st->lock);
        return ret;
}

static const struct iio_info sca3000_info = {
        .attrs = &sca3000_attribute_group,
        .read_raw = &sca3000_read_raw,
        .write_raw = &sca3000_write_raw,
        .read_event_value = &sca3000_read_event_value,
        .write_event_value = &sca3000_write_event_value,
        .read_event_config = &sca3000_read_event_config,
        .write_event_config = &sca3000_write_event_config,
};

static int sca3000_probe(struct spi_device *spi)
{
        int ret;
        struct sca3000_state *st;
        struct iio_dev *indio_dev;

        indio_dev = devm_iio_device_alloc(&spi->dev, sizeof(*st));
        if (!indio_dev)
                return -ENOMEM;

        st = iio_priv(indio_dev);
        spi_set_drvdata(spi, indio_dev);
        st->us = spi;
        mutex_init(&st->lock);
        st->info = &sca3000_spi_chip_info_tbl[spi_get_device_id(spi)
                                              ->driver_data];

        indio_dev->name = spi_get_device_id(spi)->name;
        indio_dev->info = &sca3000_info;
        if (st->info->temp_output) {
                indio_dev->channels = sca3000_channels_with_temp;
                indio_dev->num_channels =
                        ARRAY_SIZE(sca3000_channels_with_temp);
        } else {
                indio_dev->channels = sca3000_channels;
                indio_dev->num_channels = ARRAY_SIZE(sca3000_channels);
        }
        indio_dev->modes = INDIO_DIRECT_MODE;

        ret = devm_iio_kfifo_buffer_setup(&spi->dev, indio_dev,
                                          &sca3000_ring_setup_ops);
        if (ret)
                return ret;

        if (spi->irq) {
                ret = request_threaded_irq(spi->irq,
                                           NULL,
                                           &sca3000_event_handler,
                                           IRQF_TRIGGER_FALLING | IRQF_ONESHOT,
                                           "sca3000",
                                           indio_dev);
                if (ret)
                        return ret;
        }
        ret = sca3000_clean_setup(st);
        if (ret)
                goto error_free_irq;

        ret = sca3000_print_rev(indio_dev);
        if (ret)
                goto error_free_irq;

        ret = iio_device_register(indio_dev);
        if (ret)
                goto error_free_irq;

        return 0;

error_free_irq:
        if (spi->irq)
                free_irq(spi->irq, indio_dev);

        return ret;
}

static int sca3000_stop_all_interrupts(struct sca3000_state *st)
{
        int ret;

        mutex_lock(&st->lock);
        ret = sca3000_read_data_short(st, SCA3000_REG_INT_MASK_ADDR, 1);
        if (ret)
                goto error_ret;
        ret = sca3000_write_reg(st, SCA3000_REG_INT_MASK_ADDR,
                                (st->rx[0] &
                                 ~(SCA3000_REG_INT_MASK_RING_THREE_QUARTER |
                                   SCA3000_REG_INT_MASK_RING_HALF |
                                   SCA3000_REG_INT_MASK_ALL_INTS)));
error_ret:
        mutex_unlock(&st->lock);
        return ret;
}

static void sca3000_remove(struct spi_device *spi)
{
        struct iio_dev *indio_dev = spi_get_drvdata(spi);
        struct sca3000_state *st = iio_priv(indio_dev);

        iio_device_unregister(indio_dev);

        /* Must ensure no interrupts can be generated after this! */
        sca3000_stop_all_interrupts(st);
        if (spi->irq)
                free_irq(spi->irq, indio_dev);
}

static const struct spi_device_id sca3000_id[] = {
        {"sca3000_d01", d01},
        {"sca3000_e02", e02},
        {"sca3000_e04", e04},
        {"sca3000_e05", e05},
        { }
};
MODULE_DEVICE_TABLE(spi, sca3000_id);

static struct spi_driver sca3000_driver = {
        .driver = {
                .name = "sca3000",
        },
        .probe = sca3000_probe,
        .remove = sca3000_remove,
        .id_table = sca3000_id,
};
module_spi_driver(sca3000_driver);

MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
MODULE_DESCRIPTION("VTI SCA3000 Series Accelerometers SPI driver");
MODULE_LICENSE("GPL v2");