iio_dummy_evgen.c

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#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/sysfs.h>

#include "iio_dummy_evgen.h"
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>

/* Fiddly bit of faking and irq without hardware */
#define IIO_EVENTGEN_NO 10

struct iio_dummy_eventgen {
    struct irq_chip chip;
    int base;
    bool enabled[IIO_EVENTGEN_NO];
    bool inuse[IIO_EVENTGEN_NO];
    struct mutex lock;
};

/* We can only ever have one instance of this 'device' */
static struct iio_dummy_eventgen *iio_evgen;
static const char *iio_evgen_name = "iio_dummy_evgen";

static void iio_dummy_event_irqmask(struct irq_data *d)
{
    struct irq_chip *chip = irq_data_get_irq_chip(d);
    struct iio_dummy_eventgen *evgen =
        container_of(chip, struct iio_dummy_eventgen, chip);

    evgen->enabled[d->irq - evgen->base] = false;
}

static void iio_dummy_event_irqunmask(struct irq_data *d)
{
    struct irq_chip *chip = irq_data_get_irq_chip(d);
    struct iio_dummy_eventgen *evgen =
        container_of(chip, struct iio_dummy_eventgen, chip);

    evgen->enabled[d->irq - evgen->base] = true;
}

static int iio_dummy_evgen_create(void)
{
    int ret, i;

    iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
    if (iio_evgen == NULL)
        return -ENOMEM;

    iio_evgen->base = irq_alloc_descs(-1, 0, IIO_EVENTGEN_NO, 0);
    if (iio_evgen->base < 0) {
        ret = iio_evgen->base;
        kfree(iio_evgen);
        return ret;
    }
    iio_evgen->chip.name = iio_evgen_name;
    iio_evgen->chip.irq_mask = &iio_dummy_event_irqmask;
    iio_evgen->chip.irq_unmask = &iio_dummy_event_irqunmask;
    for (i = 0; i < IIO_EVENTGEN_NO; i++) {
        irq_set_chip(iio_evgen->base + i, &iio_evgen->chip);
        irq_set_handler(iio_evgen->base + i, &handle_simple_irq);
        irq_modify_status(iio_evgen->base + i,
                  IRQ_NOREQUEST | IRQ_NOAUTOEN,
                  IRQ_NOPROBE);
    }
    mutex_init(&iio_evgen->lock);
    return 0;
}

int iio_dummy_evgen_get_irq(void)
{
    int i, ret = 0;

    if (iio_evgen == NULL)
        return -ENODEV;

    mutex_lock(&iio_evgen->lock);
    for (i = 0; i < IIO_EVENTGEN_NO; i++)
        if (iio_evgen->inuse[i] == false) {
            ret = iio_evgen->base + i;
            iio_evgen->inuse[i] = true;
            break;
        }
    mutex_unlock(&iio_evgen->lock);
    if (i == IIO_EVENTGEN_NO)
        return -ENOMEM;
    return ret;
}
EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);

int iio_dummy_evgen_release_irq(int irq)
{
    mutex_lock(&iio_evgen->lock);
    iio_evgen->inuse[irq - iio_evgen->base] = false;
    mutex_unlock(&iio_evgen->lock);

    return 0;
}
EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);

static void iio_dummy_evgen_free(void)
{
    irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO);
    kfree(iio_evgen);
}

static void iio_evgen_release(struct device *dev)
{
    iio_dummy_evgen_free();
}

static ssize_t iio_evgen_poke(struct device *dev,
                  struct device_attribute *attr,
                  const char *buf,
                  size_t len)
{
    struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);

    if (iio_evgen->enabled[this_attr->address])
        handle_nested_irq(iio_evgen->base + this_attr->address);

    return len;
}

static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);

static struct attribute *iio_evgen_attrs[] = {
    &iio_dev_attr_poke_ev0.dev_attr.attr,
    &iio_dev_attr_poke_ev1.dev_attr.attr,
    &iio_dev_attr_poke_ev2.dev_attr.attr,
    &iio_dev_attr_poke_ev3.dev_attr.attr,
    &iio_dev_attr_poke_ev4.dev_attr.attr,
    &iio_dev_attr_poke_ev5.dev_attr.attr,
    &iio_dev_attr_poke_ev6.dev_attr.attr,
    &iio_dev_attr_poke_ev7.dev_attr.attr,
    &iio_dev_attr_poke_ev8.dev_attr.attr,
    &iio_dev_attr_poke_ev9.dev_attr.attr,
    NULL,
};

static const struct attribute_group iio_evgen_group = {
    .attrs = iio_evgen_attrs,
};

static const struct attribute_group *iio_evgen_groups[] = {
    &iio_evgen_group,
    NULL
};

static struct device iio_evgen_dev = {
    .bus = &iio_bus_type,
    .groups = iio_evgen_groups,
    .release = &iio_evgen_release,
};
static __init int iio_dummy_evgen_init(void)
{
    int ret = iio_dummy_evgen_create();
    if (ret < 0)
        return ret;
    device_initialize(&iio_evgen_dev);
    dev_set_name(&iio_evgen_dev, "iio_evgen");
    return device_add(&iio_evgen_dev);
}
module_init(iio_dummy_evgen_init);

static __exit void iio_dummy_evgen_exit(void)
{
    device_unregister(&iio_evgen_dev);
}
module_exit(iio_dummy_evgen_exit);

MODULE_AUTHOR("Jonathan Cameron <[email protected]>");
MODULE_DESCRIPTION("IIO dummy driver");
MODULE_LICENSE("GPL v2");