/**
 * Copyright (c) 2011 Jonathan Cameron
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * A reference industrial I/O driver to illustrate the functionality available.
 *
 * There are numerous real drivers to illustrate the finer points.
 * The purpose of this driver is to provide a driver with far more comments
 * and explanatory notes than any 'real' driver would have.
 * Anyone starting out writing an IIO driver should first make sure they
 * understand all of this driver except those bits specifically marked
 * as being present to allow us to 'fake' the presence of hardware.
 */
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/module.h>

#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/iio/events.h>
#include <linux/iio/buffer.h>
#include "iio_simple_dummy.h"

/*
 * A few elements needed to fake a bus for this driver
 * Note instances parameter controls how many of these
 * dummy devices are registered.
 */
static unsigned instances = 1;
module_param(instances, uint, 0);

/* Pointer array used to fake bus elements */
static struct iio_dev **iio_dummy_devs;

/* Fake a name for the part number, usually obtained from the id table */
static const char *iio_dummy_part_number = "iio_dummy_part_no";

/**
 * struct iio_dummy_accel_calibscale - realworld to register mapping
 * @val: first value in read_raw - here integer part.
 * @val2: second value in read_raw etc - here micro part.
 * @regval: register value - magic device specific numbers.
 */
struct iio_dummy_accel_calibscale {
        int val;
        int val2;
        int regval; /* what would be written to hardware */
};

static const struct iio_dummy_accel_calibscale dummy_scales[] = {
        { 0, 100, 0x8 }, /* 0.000100 */
        { 0, 133, 0x7 }, /* 0.000133 */
        { 733, 13, 0x9 }, /* 733.000013 */
};

#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS

/*
 * simple event - triggered when value rises above
 * a threshold
 */
static const struct iio_event_spec iio_dummy_event = {
        .type = IIO_EV_TYPE_THRESH,
        .dir = IIO_EV_DIR_RISING,
        .mask_separate = BIT(IIO_EV_INFO_VALUE) | BIT(IIO_EV_INFO_ENABLE),
};

/*
 * simple step detect event - triggered when a step is detected
 */
static const struct iio_event_spec step_detect_event = {
        .type = IIO_EV_TYPE_CHANGE,
        .dir = IIO_EV_DIR_NONE,
        .mask_separate = BIT(IIO_EV_INFO_ENABLE),
};

/*
 * simple transition event - triggered when the reported running confidence
 * value rises above a threshold value
 */
static const struct iio_event_spec iio_running_event = {
        .type = IIO_EV_TYPE_THRESH,
        .dir = IIO_EV_DIR_RISING,
        .mask_separate = BIT(IIO_EV_INFO_VALUE) | BIT(IIO_EV_INFO_ENABLE),
};

/*
 * simple transition event - triggered when the reported walking confidence
 * value falls under a threshold value
 */
static const struct iio_event_spec iio_walking_event = {
        .type = IIO_EV_TYPE_THRESH,
        .dir = IIO_EV_DIR_FALLING,
        .mask_separate = BIT(IIO_EV_INFO_VALUE) | BIT(IIO_EV_INFO_ENABLE),
};
#endif

/*
 * iio_dummy_channels - Description of available channels
 *
 * This array of structures tells the IIO core about what the device
 * actually provides for a given channel.
 */
static const struct iio_chan_spec iio_dummy_channels[] = {
        /* indexed ADC channel in_voltage0_raw etc */
        {
                .type = IIO_VOLTAGE,
                /* Channel has a numeric index of 0 */
                .indexed = 1,
                .channel = 0,
                /* What other information is available? */
                .info_mask_separate =
                /*
                 * in_voltage0_raw
                 * Raw (unscaled no bias removal etc) measurement
                 * from the device.
                 */
                BIT(IIO_CHAN_INFO_RAW) |
                /*
                 * in_voltage0_offset
                 * Offset for userspace to apply prior to scale
                 * when converting to standard units (microvolts)
                 */
                BIT(IIO_CHAN_INFO_OFFSET) |
                /*
                 * in_voltage0_scale
                 * Multipler for userspace to apply post offset
                 * when converting to standard units (microvolts)
                 */
                BIT(IIO_CHAN_INFO_SCALE),
                /*
                 * sampling_frequency
                 * The frequency in Hz at which the channels are sampled
                 */
                .info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                /* The ordering of elements in the buffer via an enum */
                .scan_index = DUMMY_INDEX_VOLTAGE_0,
                .scan_type = { /* Description of storage in buffer */
                        .sign = 'u', /* unsigned */
                        .realbits = 13, /* 13 bits */
                        .storagebits = 16, /* 16 bits used for storage */
                        .shift = 0, /* zero shift */
                },
#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
                .event_spec = &iio_dummy_event,
                .num_event_specs = 1,
#endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
        },
        /* Differential ADC channel in_voltage1-voltage2_raw etc*/
        {
                .type = IIO_VOLTAGE,
                .differential = 1,
                /*
                 * Indexing for differential channels uses channel
                 * for the positive part, channel2 for the negative.
                 */
                .indexed = 1,
                .channel = 1,
                .channel2 = 2,
                /*
                 * in_voltage1-voltage2_raw
                 * Raw (unscaled no bias removal etc) measurement
                 * from the device.
                 */
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                /*
                 * in_voltage-voltage_scale
                 * Shared version of scale - shared by differential
                 * input channels of type IIO_VOLTAGE.
                 */
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
                /*
                 * sampling_frequency
                 * The frequency in Hz at which the channels are sampled
                 */
                .scan_index = DUMMY_INDEX_DIFFVOLTAGE_1M2,
                .scan_type = { /* Description of storage in buffer */
                        .sign = 's', /* signed */
                        .realbits = 12, /* 12 bits */
                        .storagebits = 16, /* 16 bits used for storage */
                        .shift = 0, /* zero shift */
                },
        },
        /* Differential ADC channel in_voltage3-voltage4_raw etc*/
        {
                .type = IIO_VOLTAGE,
                .differential = 1,
                .indexed = 1,
                .channel = 3,
                .channel2 = 4,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
                .info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .scan_index = DUMMY_INDEX_DIFFVOLTAGE_3M4,
                .scan_type = {
                        .sign = 's',
                        .realbits = 11,
                        .storagebits = 16,
                        .shift = 0,
                },
        },
        /*
         * 'modified' (i.e. axis specified) acceleration channel
         * in_accel_z_raw
         */
        {
                .type = IIO_ACCEL,
                .modified = 1,
                /* Channel 2 is use for modifiers */
                .channel2 = IIO_MOD_X,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                /*
                 * Internal bias and gain correction values. Applied
                 * by the hardware or driver prior to userspace
                 * seeing the readings. Typically part of hardware
                 * calibration.
                 */
                BIT(IIO_CHAN_INFO_CALIBSCALE) |
                BIT(IIO_CHAN_INFO_CALIBBIAS),
                .info_mask_shared_by_dir = BIT(IIO_CHAN_INFO_SAMP_FREQ),
                .scan_index = DUMMY_INDEX_ACCELX,
                .scan_type = { /* Description of storage in buffer */
                        .sign = 's', /* signed */
                        .realbits = 16, /* 16 bits */
                        .storagebits = 16, /* 16 bits used for storage */
                        .shift = 0, /* zero shift */
                },
        },
        /*
         * Convenience macro for timestamps. 4 is the index in
         * the buffer.
         */
        IIO_CHAN_SOFT_TIMESTAMP(4),
        /* DAC channel out_voltage0_raw */
        {
                .type = IIO_VOLTAGE,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
                .scan_index = -1, /* No buffer support */
                .output = 1,
                .indexed = 1,
                .channel = 0,
        },
        {
                .type = IIO_STEPS,
                .info_mask_shared_by_type = BIT(IIO_CHAN_INFO_ENABLE) |
                        BIT(IIO_CHAN_INFO_CALIBHEIGHT),
                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
                .scan_index = -1, /* No buffer support */
#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
                .event_spec = &step_detect_event,
                .num_event_specs = 1,
#endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
        },
        {
                .type = IIO_ACTIVITY,
                .modified = 1,
                .channel2 = IIO_MOD_RUNNING,
                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
                .scan_index = -1, /* No buffer support */
#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
                .event_spec = &iio_running_event,
                .num_event_specs = 1,
#endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
        },
        {
                .type = IIO_ACTIVITY,
                .modified = 1,
                .channel2 = IIO_MOD_WALKING,
                .info_mask_separate = BIT(IIO_CHAN_INFO_PROCESSED),
                .scan_index = -1, /* No buffer support */
#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
                .event_spec = &iio_walking_event,
                .num_event_specs = 1,
#endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
        },
};

/**
 * iio_dummy_read_raw() - data read function.
 * @indio_dev:  the struct iio_dev associated with this device instance
 * @chan:       the channel whose data is to be read
 * @val:        first element of returned value (typically INT)
 * @val2:       second element of returned value (typically MICRO)
 * @mask:       what we actually want to read as per the info_mask_*
 *              in iio_chan_spec.
 */
static int iio_dummy_read_raw(struct iio_dev *indio_dev,
                              struct iio_chan_spec const *chan,
                              int *val,
                              int *val2,
                              long mask)
{
        struct iio_dummy_state *st = iio_priv(indio_dev);
        int ret = -EINVAL;

        mutex_lock(&st->lock);
        switch (mask) {
        case IIO_CHAN_INFO_RAW: /* magic value - channel value read */
                switch (chan->type) {
                case IIO_VOLTAGE:
                        if (chan->output) {
                                /* Set integer part to cached value */
                                *val = st->dac_val;
                                ret = IIO_VAL_INT;
                        } else if (chan->differential) {
                                if (chan->channel == 1)
                                        *val = st->differential_adc_val[0];
                                else
                                        *val = st->differential_adc_val[1];
                                ret = IIO_VAL_INT;
                        } else {
                                *val = st->single_ended_adc_val;
                                ret = IIO_VAL_INT;
                        }
                        break;
                case IIO_ACCEL:
                        *val = st->accel_val;
                        ret = IIO_VAL_INT;
                        break;
                default:
                        break;
                }
                break;
        case IIO_CHAN_INFO_PROCESSED:
                switch (chan->type) {
                case IIO_STEPS:
                        *val = st->steps;
                        ret = IIO_VAL_INT;
                        break;
                case IIO_ACTIVITY:
                        switch (chan->channel2) {
                        case IIO_MOD_RUNNING:
                                *val = st->activity_running;
                                ret = IIO_VAL_INT;
                                break;
                        case IIO_MOD_WALKING:
                                *val = st->activity_walking;
                                ret = IIO_VAL_INT;
                                break;
                        default:
                                break;
                        }
                        break;
                default:
                        break;
                }
                break;
        case IIO_CHAN_INFO_OFFSET:
                /* only single ended adc -> 7 */
                *val = 7;
                ret = IIO_VAL_INT;
                break;
        case IIO_CHAN_INFO_SCALE:
                switch (chan->type) {
                case IIO_VOLTAGE:
                        switch (chan->differential) {
                        case 0:
                                /* only single ended adc -> 0.001333 */
                                *val = 0;
                                *val2 = 1333;
                                ret = IIO_VAL_INT_PLUS_MICRO;
                                break;
                        case 1:
                                /* all differential adc -> 0.000001344 */
                                *val = 0;
                                *val2 = 1344;
                                ret = IIO_VAL_INT_PLUS_NANO;
                        }
                        break;
                default:
                        break;
                }
                break;
        case IIO_CHAN_INFO_CALIBBIAS:
                /* only the acceleration axis - read from cache */
                *val = st->accel_calibbias;
                ret = IIO_VAL_INT;
                break;
        case IIO_CHAN_INFO_CALIBSCALE:
                *val = st->accel_calibscale->val;
                *val2 = st->accel_calibscale->val2;
                ret = IIO_VAL_INT_PLUS_MICRO;
                break;
        case IIO_CHAN_INFO_SAMP_FREQ:
                *val = 3;
                *val2 = 33;
                ret = IIO_VAL_INT_PLUS_NANO;
                break;
        case IIO_CHAN_INFO_ENABLE:
                switch (chan->type) {
                case IIO_STEPS:
                        *val = st->steps_enabled;
                        ret = IIO_VAL_INT;
                        break;
                default:
                        break;
                }
                break;
        case IIO_CHAN_INFO_CALIBHEIGHT:
                switch (chan->type) {
                case IIO_STEPS:
                        *val = st->height;
                        ret = IIO_VAL_INT;
                        break;
                default:
                        break;
                }
                break;

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

/**
 * iio_dummy_write_raw() - data write function.
 * @indio_dev:  the struct iio_dev associated with this device instance
 * @chan:       the channel whose data is to be written
 * @val:        first element of value to set (typically INT)
 * @val2:       second element of value to set (typically MICRO)
 * @mask:       what we actually want to write as per the info_mask_*
 *              in iio_chan_spec.
 *
 * Note that all raw writes are assumed IIO_VAL_INT and info mask elements
 * are assumed to be IIO_INT_PLUS_MICRO unless the callback write_raw_get_fmt
 * in struct iio_info is provided by the driver.
 */
static int iio_dummy_write_raw(struct iio_dev *indio_dev,
                               struct iio_chan_spec const *chan,
                               int val,
                               int val2,
                               long mask)
{
        int i;
        int ret = 0;
        struct iio_dummy_state *st = iio_priv(indio_dev);

        switch (mask) {
        case IIO_CHAN_INFO_RAW:
                switch (chan->type) {
                case IIO_VOLTAGE:
                        if (chan->output == 0)
                                return -EINVAL;

                        /* Locking not required as writing single value */
                        mutex_lock(&st->lock);
                        st->dac_val = val;
                        mutex_unlock(&st->lock);
                        return 0;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_PROCESSED:
                switch (chan->type) {
                case IIO_STEPS:
                        mutex_lock(&st->lock);
                        st->steps = val;
                        mutex_unlock(&st->lock);
                        return 0;
                case IIO_ACTIVITY:
                        if (val < 0)
                                val = 0;
                        if (val > 100)
                                val = 100;
                        switch (chan->channel2) {
                        case IIO_MOD_RUNNING:
                                st->activity_running = val;
                                return 0;
                        case IIO_MOD_WALKING:
                                st->activity_walking = val;
                                return 0;
                        default:
                                return -EINVAL;
                        }
                        break;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_CALIBSCALE:
                mutex_lock(&st->lock);
                /* Compare against table - hard matching here */
                for (i = 0; i < ARRAY_SIZE(dummy_scales); i++)
                        if (val == dummy_scales[i].val &&
                            val2 == dummy_scales[i].val2)
                                break;
                if (i == ARRAY_SIZE(dummy_scales))
                        ret = -EINVAL;
                else
                        st->accel_calibscale = &dummy_scales[i];
                mutex_unlock(&st->lock);
                return ret;
        case IIO_CHAN_INFO_CALIBBIAS:
                mutex_lock(&st->lock);
                st->accel_calibbias = val;
                mutex_unlock(&st->lock);
                return 0;
        case IIO_CHAN_INFO_ENABLE:
                switch (chan->type) {
                case IIO_STEPS:
                        mutex_lock(&st->lock);
                        st->steps_enabled = val;
                        mutex_unlock(&st->lock);
                        return 0;
                default:
                        return -EINVAL;
                }
        case IIO_CHAN_INFO_CALIBHEIGHT:
                switch (chan->type) {
                case IIO_STEPS:
                        st->height = val;
                        return 0;
                default:
                        return -EINVAL;
                }

        default:
                return -EINVAL;
        }
}

/*
 * Device type specific information.
 */
static const struct iio_info iio_dummy_info = {
        .driver_module = THIS_MODULE,
        .read_raw = &iio_dummy_read_raw,
        .write_raw = &iio_dummy_write_raw,
#ifdef CONFIG_IIO_SIMPLE_DUMMY_EVENTS
        .read_event_config = &iio_simple_dummy_read_event_config,
        .write_event_config = &iio_simple_dummy_write_event_config,
        .read_event_value = &iio_simple_dummy_read_event_value,
        .write_event_value = &iio_simple_dummy_write_event_value,
#endif /* CONFIG_IIO_SIMPLE_DUMMY_EVENTS */
};

/**
 * iio_dummy_init_device() - device instance specific init
 * @indio_dev: the iio device structure
 *
 * Most drivers have one of these to set up default values,
 * reset the device to known state etc.
 */
static int iio_dummy_init_device(struct iio_dev *indio_dev)
{
        struct iio_dummy_state *st = iio_priv(indio_dev);

        st->dac_val = 0;
        st->single_ended_adc_val = 73;
        st->differential_adc_val[0] = 33;
        st->differential_adc_val[1] = -34;
        st->accel_val = 34;
        st->accel_calibbias = -7;
        st->accel_calibscale = &dummy_scales[0];
        st->steps = 47;
        st->activity_running = 98;
        st->activity_walking = 4;

        return 0;
}

/**
 * iio_dummy_probe() - device instance probe
 * @index: an id number for this instance.
 *
 * Arguments are bus type specific.
 * I2C: iio_dummy_probe(struct i2c_client *client,
 *                      const struct i2c_device_id *id)
 * SPI: iio_dummy_probe(struct spi_device *spi)
 */
static int iio_dummy_probe(int index)
{
        int ret;
        struct iio_dev *indio_dev;
        struct iio_dummy_state *st;

        /*
         * Allocate an IIO device.
         *
         * This structure contains all generic state
         * information about the device instance.
         * It also has a region (accessed by iio_priv()
         * for chip specific state information.
         */
        indio_dev = iio_device_alloc(sizeof(*st));
        if (!indio_dev) {
                ret = -ENOMEM;
                goto error_ret;
        }

        st = iio_priv(indio_dev);
        mutex_init(&st->lock);

        iio_dummy_init_device(indio_dev);
        /*
         * With hardware: Set the parent device.
         * indio_dev->dev.parent = &spi->dev;
         * indio_dev->dev.parent = &client->dev;
         */

         /*
         * Make the iio_dev struct available to remove function.
         * Bus equivalents
         * i2c_set_clientdata(client, indio_dev);
         * spi_set_drvdata(spi, indio_dev);
         */
        iio_dummy_devs[index] = indio_dev;

        /*
         * Set the device name.
         *
         * This is typically a part number and obtained from the module
         * id table.
         * e.g. for i2c and spi:
         *    indio_dev->name = id->name;
         *    indio_dev->name = spi_get_device_id(spi)->name;
         */
        indio_dev->name = iio_dummy_part_number;

        /* Provide description of available channels */
        indio_dev->channels = iio_dummy_channels;
        indio_dev->num_channels = ARRAY_SIZE(iio_dummy_channels);

        /*
         * Provide device type specific interface functions and
         * constant data.
         */
        indio_dev->info = &iio_dummy_info;

        /* Specify that device provides sysfs type interfaces */
        indio_dev->modes = INDIO_DIRECT_MODE;

        ret = iio_simple_dummy_events_register(indio_dev);
        if (ret < 0)
                goto error_free_device;

        ret = iio_simple_dummy_configure_buffer(indio_dev);
        if (ret < 0)
                goto error_unregister_events;

        ret = iio_device_register(indio_dev);
        if (ret < 0)
                goto error_unconfigure_buffer;

        return 0;
error_unconfigure_buffer:
        iio_simple_dummy_unconfigure_buffer(indio_dev);
error_unregister_events:
        iio_simple_dummy_events_unregister(indio_dev);
error_free_device:
        iio_device_free(indio_dev);
error_ret:
        return ret;
}

/**
 * iio_dummy_remove() - device instance removal function
 * @index: device index.
 *
 * Parameters follow those of iio_dummy_probe for buses.
 */
static void iio_dummy_remove(int index)
{
        /*
         * Get a pointer to the device instance iio_dev structure
         * from the bus subsystem. E.g.
         * struct iio_dev *indio_dev = i2c_get_clientdata(client);
         * struct iio_dev *indio_dev = spi_get_drvdata(spi);
         */
        struct iio_dev *indio_dev = iio_dummy_devs[index];

        /* Unregister the device */
        iio_device_unregister(indio_dev);

        /* Device specific code to power down etc */

        /* Buffered capture related cleanup */
        iio_simple_dummy_unconfigure_buffer(indio_dev);

        iio_simple_dummy_events_unregister(indio_dev);

        /* Free all structures */
        iio_device_free(indio_dev);
}

/**
 * iio_dummy_init() -  device driver registration
 *
 * Varies depending on bus type of the device. As there is no device
 * here, call probe directly. For information on device registration
 * i2c:
 * Documentation/i2c/writing-clients
 * spi:
 * Documentation/spi/spi-summary
 */
static __init int iio_dummy_init(void)
{
        int i, ret;

        if (instances > 10) {
                instances = 1;
                return -EINVAL;
        }

        /* Fake a bus */
        iio_dummy_devs = kcalloc(instances, sizeof(*iio_dummy_devs),
                                 GFP_KERNEL);
        /* Here we have no actual device so call probe */
        for (i = 0; i < instances; i++) {
                ret = iio_dummy_probe(i);
                if (ret < 0)
                        goto error_remove_devs;
        }
        return 0;

error_remove_devs:
        while (i--)
                iio_dummy_remove(i);

        kfree(iio_dummy_devs);
        return ret;
}
module_init(iio_dummy_init);

/**
 * iio_dummy_exit() - device driver removal
 *
 * Varies depending on bus type of the device.
 * As there is no device here, call remove directly.
 */
static __exit void iio_dummy_exit(void)
{
        int i;

        for (i = 0; i < instances; i++)
                iio_dummy_remove(i);
        kfree(iio_dummy_devs);
}
module_exit(iio_dummy_exit);

MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
MODULE_DESCRIPTION("IIO dummy driver");
MODULE_LICENSE("GPL v2");