#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/gpio.h>
#include <linux/workqueue.h>
#include <linux/mutex.h>
#include <linux/device.h>
#include <linux/kernel.h>
#include <linux/spi/spi.h>
#include <linux/sysfs.h>
#include <linux/list.h>

#include "../iio.h"
#include "../sysfs.h"
#include "../ring_sw.h"
#include "accel.h"
#include "../trigger.h"
#include "lis3l02dq.h"

/**
 * combine_8_to_16() utility function to munge to u8s into u16
 **/
static inline u16 combine_8_to_16(u8 lower, u8 upper)
{
        u16 _lower = lower;
        u16 _upper = upper;
        return _lower | (_upper << 8);
}

/**
 * lis3l02dq_scan_el_set_state() set whether a scan contains a given channel
 * @scan_el:    associtate iio scan element attribute
 * @indio_dev:  the device structure
 * @bool:       desired state
 *
 * mlock already held when this is called.
 **/
static int lis3l02dq_scan_el_set_state(struct iio_scan_el *scan_el,
                                       struct iio_dev *indio_dev,
                                       bool state)
{
        u8 t, mask;
        int ret;

        ret = lis3l02dq_spi_read_reg_8(&indio_dev->dev,
                                       LIS3L02DQ_REG_CTRL_1_ADDR,
                                       &t);
        if (ret)
                goto error_ret;
        switch (scan_el->label) {
        case LIS3L02DQ_REG_OUT_X_L_ADDR:
                mask = LIS3L02DQ_REG_CTRL_1_AXES_X_ENABLE;
                break;
        case LIS3L02DQ_REG_OUT_Y_L_ADDR:
                mask = LIS3L02DQ_REG_CTRL_1_AXES_Y_ENABLE;
                break;
        case LIS3L02DQ_REG_OUT_Z_L_ADDR:
                mask = LIS3L02DQ_REG_CTRL_1_AXES_Z_ENABLE;
                break;
        default:
                ret = -EINVAL;
                goto error_ret;
        }

        if (!(mask & t) == state) {
                if (state)
                        t |= mask;
                else
                        t &= ~mask;
                ret = lis3l02dq_spi_write_reg_8(&indio_dev->dev,
                                                LIS3L02DQ_REG_CTRL_1_ADDR,
                                                &t);
        }
error_ret:
        return ret;

}
static IIO_SCAN_EL_C(accel_x, LIS3L02DQ_SCAN_ACC_X, IIO_SIGNED(16),
                     LIS3L02DQ_REG_OUT_X_L_ADDR,
                     &lis3l02dq_scan_el_set_state);
static IIO_SCAN_EL_C(accel_y, LIS3L02DQ_SCAN_ACC_Y, IIO_SIGNED(16),
                     LIS3L02DQ_REG_OUT_Y_L_ADDR,
                     &lis3l02dq_scan_el_set_state);
static IIO_SCAN_EL_C(accel_z, LIS3L02DQ_SCAN_ACC_Z, IIO_SIGNED(16),
                     LIS3L02DQ_REG_OUT_Z_L_ADDR,
                     &lis3l02dq_scan_el_set_state);
static IIO_SCAN_EL_TIMESTAMP;

static struct attribute *lis3l02dq_scan_el_attrs[] = {
        &iio_scan_el_accel_x.dev_attr.attr,
        &iio_scan_el_accel_y.dev_attr.attr,
        &iio_scan_el_accel_z.dev_attr.attr,
        &iio_scan_el_timestamp.dev_attr.attr,
        NULL,
};

static struct attribute_group lis3l02dq_scan_el_group = {
        .attrs = lis3l02dq_scan_el_attrs,
        .name = "scan_elements",
};

/**
 * lis3l02dq_poll_func_th() top half interrupt handler called by trigger
 * @private_data:       iio_dev
 **/
static void lis3l02dq_poll_func_th(struct iio_dev *indio_dev)
{
  struct lis3l02dq_state *st = iio_dev_get_devdata(indio_dev);
        st->last_timestamp = indio_dev->trig->timestamp;
        schedule_work(&st->work_trigger_to_ring);
        /* Indicate that this interrupt is being handled */

        /* Technically this is trigger related, but without this
         * handler running there is currently now way for the interrupt
         * to clear.
         */
        st->inter = 1;
}

/**
 * lis3l02dq_data_rdy_trig_poll() the event handler for the data rdy trig
 **/
static int lis3l02dq_data_rdy_trig_poll(struct iio_dev *dev_info,
                                       int index,
                                       s64 timestamp,
                                       int no_test)
{
        struct lis3l02dq_state *st = iio_dev_get_devdata(dev_info);
        struct iio_trigger *trig = st->trig;

        trig->timestamp = timestamp;
        iio_trigger_poll(trig);

        return IRQ_HANDLED;
}

/* This is an event as it is a response to a physical interrupt */
IIO_EVENT_SH(data_rdy_trig, &lis3l02dq_data_rdy_trig_poll);

/**
 * lis3l02dq_read_accel_from_ring() individual acceleration read from ring
 **/
ssize_t lis3l02dq_read_accel_from_ring(struct device *dev,
                                       struct device_attribute *attr,
                                       char *buf)
{
        struct iio_scan_el *el = NULL;
        int ret, len = 0, i = 0;
        struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
        struct iio_dev *dev_info = dev_get_drvdata(dev);
        s16 *data;

        while (dev_info->scan_el_attrs->attrs[i]) {
                el = to_iio_scan_el((struct device_attribute *)
                                    (dev_info->scan_el_attrs->attrs[i]));
                /* label is in fact the address */
                if (el->label == this_attr->address)
                        break;
                i++;
        }
        if (!dev_info->scan_el_attrs->attrs[i]) {
                ret = -EINVAL;
                goto error_ret;
        }
        /* If this element is in the scan mask */
        ret = iio_scan_mask_query(dev_info, el->number);
        if (ret < 0)
                goto error_ret;
        if (ret) {
                data = kmalloc(dev_info->ring->access.get_bpd(dev_info->ring),
                               GFP_KERNEL);
                if (data == NULL)
                        return -ENOMEM;
                ret = dev_info->ring->access.read_last(dev_info->ring,
                                                      (u8 *)data);
                if (ret)
                        goto error_free_data;
        } else {
                ret = -EINVAL;
                goto error_ret;
        }
        len = iio_scan_mask_count_to_right(dev_info, el->number);
        if (len < 0) {
                ret = len;
                goto error_free_data;
        }
        len = sprintf(buf, "ring %d\n", data[len]);
error_free_data:
        kfree(data);
error_ret:
        return ret ? ret : len;

}

static const u8 read_all_tx_array[] =
{
        LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_X_L_ADDR), 0,
        LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_X_H_ADDR), 0,
        LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_Y_L_ADDR), 0,
        LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_Y_H_ADDR), 0,
        LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_Z_L_ADDR), 0,
        LIS3L02DQ_READ_REG(LIS3L02DQ_REG_OUT_Z_H_ADDR), 0,
};

/**
 * lis3l02dq_read_all() Reads all channels currently selected
 * @st:         device specific state
 * @rx_array:   (dma capable) recieve array, must be at least
 *              4*number of channels
 **/
int lis3l02dq_read_all(struct lis3l02dq_state *st, u8 *rx_array)
{
        struct spi_transfer *xfers;
        struct spi_message msg;
        int ret, i, j = 0;

        xfers = kzalloc((st->indio_dev->scan_count) * 2
                        * sizeof(*xfers), GFP_KERNEL);
        if (!xfers)
                return -ENOMEM;

        mutex_lock(&st->buf_lock);

        for (i = 0; i < ARRAY_SIZE(read_all_tx_array)/4; i++) {
                if (st->indio_dev->scan_mask & (1 << i)) {
                        /* lower byte */
                        xfers[j].tx_buf = st->tx + 2*j;
                        st->tx[2*j] = read_all_tx_array[i*4];
                        st->tx[2*j + 1] = 0;
                        if (rx_array)
                                xfers[j].rx_buf = rx_array + j*2;
                        xfers[j].bits_per_word = 8;
                        xfers[j].len = 2;
                        xfers[j].cs_change = 1;
                        j++;

                        /* upper byte */
                        xfers[j].tx_buf = st->tx + 2*j;
                        st->tx[2*j] = read_all_tx_array[i*4 + 2];
                        st->tx[2*j + 1] = 0;
                        if (rx_array)
                                xfers[j].rx_buf = rx_array + j*2;
                        xfers[j].bits_per_word = 8;
                        xfers[j].len = 2;
                        xfers[j].cs_change = 1;
                        j++;
                }
        }
        /* After these are transmitted, the rx_buff should have
         * values in alternate bytes
         */
        spi_message_init(&msg);
        for (j = 0; j < st->indio_dev->scan_count * 2; j++)
                spi_message_add_tail(&xfers[j], &msg);

        ret = spi_sync(st->us, &msg);
        mutex_unlock(&st->buf_lock);
        kfree(xfers);

        return ret;
}


/* Whilst this makes a lot of calls to iio_sw_ring functions - it is to device
 * specific to be rolled into the core.
 */
static void lis3l02dq_trigger_bh_to_ring(struct work_struct *work_s)
{
        struct lis3l02dq_state *st
                = container_of(work_s, struct lis3l02dq_state,
                               work_trigger_to_ring);

        u8 *rx_array;
        int i = 0;
        u16 *data;
        size_t datasize = st->indio_dev
                ->ring->access.get_bpd(st->indio_dev->ring);

        data = kmalloc(datasize , GFP_KERNEL);
        if (data == NULL) {
                dev_err(&st->us->dev, "memory alloc failed in ring bh");
                return;
        }
        /* Due to interleaved nature of transmission this buffer must be
         * twice the number of bytes, or 4 times the number of channels
         */
        rx_array = kmalloc(4 * (st->indio_dev->scan_count), GFP_KERNEL);
        if (rx_array == NULL) {
                dev_err(&st->us->dev, "memory alloc failed in ring bh");
                kfree(data);
                return;
        }

        /* whilst trigger specific, if this read does nto occur the data
           ready interrupt will not be cleared.  Need to add a mechanism
           to provide a dummy read function if this is not triggering on
           the data ready function but something else is.
        */
        st->inter = 0;

        if (st->indio_dev->scan_count)
                if (lis3l02dq_read_all(st, rx_array) >= 0)
                        for (; i < st->indio_dev->scan_count; i++)
                                data[i] = combine_8_to_16(rx_array[i*4+1],
                                                          rx_array[i*4+3]);
        /* Guaranteed to be aligned with 8 byte boundary */
        if (st->indio_dev->scan_timestamp)
                *((s64 *)(data + ((i + 3)/4)*4)) = st->last_timestamp;

        st->indio_dev->ring->access.store_to(st->indio_dev->ring,
                                            (u8 *)data,
                                            st->last_timestamp);

        iio_trigger_notify_done(st->indio_dev->trig);
        kfree(rx_array);
        kfree(data);

        return;
}
/* in these circumstances is it better to go with unaligned packing and
 * deal with the cost?*/
static int lis3l02dq_data_rdy_ring_preenable(struct iio_dev *indio_dev)
{
        size_t size;
        /* Check if there are any scan elements enabled, if not fail*/
        if (!(indio_dev->scan_count || indio_dev->scan_timestamp))
                return -EINVAL;

        if (indio_dev->ring->access.set_bpd) {
                if (indio_dev->scan_timestamp)
                        if (indio_dev->scan_count) /* Timestamp and data */
                                size = 2*sizeof(s64);
                        else /* Timestamp only  */
                                size = sizeof(s64);
                else /* Data only */
                        size = indio_dev->scan_count*sizeof(s16);
                indio_dev->ring->access.set_bpd(indio_dev->ring, size);
        }

        return 0;
}

static int lis3l02dq_data_rdy_ring_postenable(struct iio_dev *indio_dev)
{
        return indio_dev->trig
                ? iio_trigger_attach_poll_func(indio_dev->trig,
                                               indio_dev->pollfunc)
                : 0;
}

static int lis3l02dq_data_rdy_ring_predisable(struct iio_dev *indio_dev)
{
        return indio_dev->trig
                ? iio_trigger_dettach_poll_func(indio_dev->trig,
                                                indio_dev->pollfunc)
                : 0;
}


/* Caller responsible for locking as necessary. */
static int __lis3l02dq_write_data_ready_config(struct device *dev,
                                               struct
                                               iio_event_handler_list *list,
                                               bool state)
{
        int ret;
        u8 valold;
        bool currentlyset;
        struct iio_dev *indio_dev = dev_get_drvdata(dev);

/* Get the current event mask register */
        ret = lis3l02dq_spi_read_reg_8(dev,
                                       LIS3L02DQ_REG_CTRL_2_ADDR,
                                       &valold);
        if (ret)
                goto error_ret;
/* Find out if data ready is already on */
        currentlyset
                = valold & LIS3L02DQ_REG_CTRL_2_ENABLE_DATA_READY_GENERATION;

/* Disable requested */
        if (!state && currentlyset) {

                valold &= ~LIS3L02DQ_REG_CTRL_2_ENABLE_DATA_READY_GENERATION;
                /* The double write is to overcome a hardware bug?*/
                ret = lis3l02dq_spi_write_reg_8(dev,
                                                LIS3L02DQ_REG_CTRL_2_ADDR,
                                                &valold);
                if (ret)
                        goto error_ret;
                ret = lis3l02dq_spi_write_reg_8(dev,
                                                LIS3L02DQ_REG_CTRL_2_ADDR,
                                                &valold);
                if (ret)
                        goto error_ret;

                iio_remove_event_from_list(list,
                                           &indio_dev->interrupts[0]
                                           ->ev_list);

/* Enable requested */
        } else if (state && !currentlyset) {
                /* if not set, enable requested */
                valold |= LIS3L02DQ_REG_CTRL_2_ENABLE_DATA_READY_GENERATION;
                iio_add_event_to_list(list, &indio_dev->interrupts[0]->ev_list);
                ret = lis3l02dq_spi_write_reg_8(dev,
                                                LIS3L02DQ_REG_CTRL_2_ADDR,
                                                &valold);
                if (ret)
                        goto error_ret;
        }

        return 0;
error_ret:
        return ret;
}

/**
 * lis3l02dq_data_rdy_trigger_set_state() set datardy interrupt state
 *
 * If disabling the interrupt also does a final read to ensure it is clear.
 * This is only important in some cases where the scan enable elements are
 * switched before the ring is reenabled.
 **/
static int lis3l02dq_data_rdy_trigger_set_state(struct iio_trigger *trig,
                                                bool state)
{
        struct lis3l02dq_state *st = trig->private_data;
        int ret = 0;
        u8 t;
        __lis3l02dq_write_data_ready_config(&st->indio_dev->dev,
                                            &iio_event_data_rdy_trig,
                                            state);
        if (state == false) {
                /* possible quirk with handler currently worked around
                   by ensuring the work queue is empty */
                flush_scheduled_work();
                /* Clear any outstanding ready events */
                ret = lis3l02dq_read_all(st, NULL);
        }
        lis3l02dq_spi_read_reg_8(&st->indio_dev->dev,
                                 LIS3L02DQ_REG_WAKE_UP_SRC_ADDR,
                                 &t);
        return ret;
}
static DEVICE_ATTR(name, S_IRUGO, iio_trigger_read_name, NULL);

static struct attribute *lis3l02dq_trigger_attrs[] = {
        &dev_attr_name.attr,
        NULL,
};

static const struct attribute_group lis3l02dq_trigger_attr_group = {
        .attrs = lis3l02dq_trigger_attrs,
};

/**
 * lis3l02dq_trig_try_reen() try renabling irq for data rdy trigger
 * @trig:       the datardy trigger
 *
 * As the trigger may occur on any data element being updated it is
 * really rather likely to occur during the read from the previous
 * trigger event.  The only way to discover if this has occured on
 * boards not supporting level interrupts is to take a look at the line.
 * If it is indicating another interrupt and we don't seem to have a
 * handler looking at it, then we need to notify the core that we need
 * to tell the triggering core to try reading all these again.
 **/
static int lis3l02dq_trig_try_reen(struct iio_trigger *trig)
{
        struct lis3l02dq_state *st = trig->private_data;
        enable_irq(st->us->irq);
        /* If gpio still high (or high again) */
        if (gpio_get_value(irq_to_gpio(st->us->irq)))
                if (st->inter == 0) {
                        /* already interrupt handler dealing with it */
                        disable_irq_nosync(st->us->irq);
                        if (st->inter == 1) {
                                /* interrupt handler snuck in between test
                                 * and disable */
                                enable_irq(st->us->irq);
                                return 0;
                        }
                        return -EAGAIN;
                }
        /* irq reenabled so success! */
        return 0;
}

int lis3l02dq_probe_trigger(struct iio_dev *indio_dev)
{
        int ret;
        struct lis3l02dq_state *state = indio_dev->dev_data;

        state->trig = iio_allocate_trigger();
        state->trig->name = kmalloc(IIO_TRIGGER_NAME_LENGTH, GFP_KERNEL);
        if (!state->trig->name) {
                ret = -ENOMEM;
                goto error_free_trig;
        }
        snprintf((char *)state->trig->name,
                 IIO_TRIGGER_NAME_LENGTH,
                 "lis3l02dq-dev%d", indio_dev->id);
        state->trig->dev.parent = &state->us->dev;
        state->trig->owner = THIS_MODULE;
        state->trig->private_data = state;
        state->trig->set_trigger_state = &lis3l02dq_data_rdy_trigger_set_state;
        state->trig->try_reenable = &lis3l02dq_trig_try_reen;
        state->trig->control_attrs = &lis3l02dq_trigger_attr_group;
        ret = iio_trigger_register(state->trig);
        if (ret)
                goto error_free_trig_name;

        return 0;

error_free_trig_name:
        kfree(state->trig->name);
error_free_trig:
        iio_free_trigger(state->trig);

        return ret;
}

void lis3l02dq_remove_trigger(struct iio_dev *indio_dev)
{
        struct lis3l02dq_state *state = indio_dev->dev_data;

        iio_trigger_unregister(state->trig);
        kfree(state->trig->name);
        iio_free_trigger(state->trig);
}

void lis3l02dq_unconfigure_ring(struct iio_dev *indio_dev)
{
        kfree(indio_dev->pollfunc);
        iio_sw_rb_free(indio_dev->ring);
}

int lis3l02dq_configure_ring(struct iio_dev *indio_dev)
{
        int ret = 0;
        struct lis3l02dq_state *st = indio_dev->dev_data;
        struct iio_ring_buffer *ring;
        INIT_WORK(&st->work_trigger_to_ring, lis3l02dq_trigger_bh_to_ring);
        /* Set default scan mode */

        iio_scan_mask_set(indio_dev, iio_scan_el_accel_x.number);
        iio_scan_mask_set(indio_dev, iio_scan_el_accel_y.number);
        iio_scan_mask_set(indio_dev, iio_scan_el_accel_z.number);
        indio_dev->scan_timestamp = true;

        indio_dev->scan_el_attrs = &lis3l02dq_scan_el_group;

        ring = iio_sw_rb_allocate(indio_dev);
        if (!ring) {
                ret = -ENOMEM;
                return ret;
        }
        indio_dev->ring = ring;
        /* Effectively select the ring buffer implementation */
        iio_ring_sw_register_funcs(&ring->access);
        ring->preenable = &lis3l02dq_data_rdy_ring_preenable;
        ring->postenable = &lis3l02dq_data_rdy_ring_postenable;
        ring->predisable = &lis3l02dq_data_rdy_ring_predisable;
        ring->owner = THIS_MODULE;

        indio_dev->pollfunc = kzalloc(sizeof(*indio_dev->pollfunc), GFP_KERNEL);
        if (indio_dev->pollfunc == NULL) {
                ret = -ENOMEM;
                goto error_iio_sw_rb_free;;
        }
        indio_dev->pollfunc->poll_func_main = &lis3l02dq_poll_func_th;
        indio_dev->pollfunc->private_data = indio_dev;
        indio_dev->modes |= INDIO_RING_TRIGGERED;
        return 0;

error_iio_sw_rb_free:
        iio_sw_rb_free(indio_dev->ring);
        return ret;
}

int lis3l02dq_initialize_ring(struct iio_ring_buffer *ring)
{
        return iio_ring_buffer_register(ring);
}

void lis3l02dq_uninitialize_ring(struct iio_ring_buffer *ring)
{
        iio_ring_buffer_unregister(ring);
}


int lis3l02dq_set_ring_length(struct iio_dev *indio_dev, int length)
{
        /* Set sensible defaults for the ring buffer */
        if (indio_dev->ring->access.set_length)
                return indio_dev->ring->access.set_length(indio_dev->ring, 500);
        return 0;
}