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+/**
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+ * Copyright (c) 2011 Jonathan Cameron
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+ *
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+ * This program is free software; you can redistribute it and/or modify it
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+ * under the terms of the GNU General Public License version 2 as published by
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+ * the Free Software Foundation.
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+ *
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+ * Companion module to the iio simple dummy example driver.
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+ * The purpose of this is to generate 'fake' event interrupts thus
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+ * allowing that driver's code to be as close as possible to that of
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+ * a normal driver talking to hardware. The approach used here
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+ * is not intended to be general and just happens to work for this
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+ * particular use case.
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+ */
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+
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+#include <linux/kernel.h>
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+#include <linux/slab.h>
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+#include <linux/interrupt.h>
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+#include <linux/irq.h>
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+#include <linux/mutex.h>
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+#include <linux/module.h>
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+#include <linux/sysfs.h>
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+
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+#include "iio_dummy_evgen.h"
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+#include "iio.h"
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+#include "sysfs.h"
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+
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+/* Fiddly bit of faking and irq without hardware */
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+#define IIO_EVENTGEN_NO 10
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+/**
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+ * struct iio_dummy_evgen - evgen state
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+ * @chip: irq chip we are faking
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+ * @base: base of irq range
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+ * @enabled: mask of which irqs are enabled
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+ * @inuse: mask of which irqs actually have anyone connected
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+ * @lock: protect the evgen state
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+ */
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+struct iio_dummy_eventgen {
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+ struct irq_chip chip;
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+ int base;
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+ bool enabled[IIO_EVENTGEN_NO];
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+ bool inuse[IIO_EVENTGEN_NO];
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+ struct mutex lock;
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+};
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+
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+/* We can only ever have one instance of this 'device' */
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+static struct iio_dummy_eventgen *iio_evgen;
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+static const char *iio_evgen_name = "iio_dummy_evgen";
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+
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+static void iio_dummy_event_irqmask(struct irq_data *d)
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+{
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+ struct irq_chip *chip = irq_data_get_irq_chip(d);
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+ struct iio_dummy_eventgen *evgen =
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+ container_of(chip, struct iio_dummy_eventgen, chip);
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+
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+ evgen->enabled[d->irq - evgen->base] = false;
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+}
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+
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+static void iio_dummy_event_irqunmask(struct irq_data *d)
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+{
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+ struct irq_chip *chip = irq_data_get_irq_chip(d);
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+ struct iio_dummy_eventgen *evgen =
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+ container_of(chip, struct iio_dummy_eventgen, chip);
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+
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+ evgen->enabled[d->irq - evgen->base] = true;
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+}
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+
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+static int iio_dummy_evgen_create(void)
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+{
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+ int ret, i;
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+
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+ iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
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+ if (iio_evgen == NULL)
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+ return -ENOMEM;
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+
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+ iio_evgen->base = irq_alloc_descs(-1, 0, IIO_EVENTGEN_NO, 0);
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+ if (iio_evgen->base < 0) {
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+ ret = iio_evgen->base;
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+ kfree(iio_evgen);
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+ return ret;
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+ }
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+ iio_evgen->chip.name = iio_evgen_name;
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+ iio_evgen->chip.irq_mask = &iio_dummy_event_irqmask;
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+ iio_evgen->chip.irq_unmask = &iio_dummy_event_irqunmask;
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+ for (i = 0; i < IIO_EVENTGEN_NO; i++) {
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+ irq_set_chip(iio_evgen->base + i, &iio_evgen->chip);
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+ irq_set_handler(iio_evgen->base + i, &handle_simple_irq);
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+ irq_modify_status(iio_evgen->base + i,
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+ IRQ_NOREQUEST | IRQ_NOAUTOEN,
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+ IRQ_NOPROBE);
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+ }
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+ mutex_init(&iio_evgen->lock);
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+ return 0;
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+}
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+
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+/**
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+ * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device
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+ *
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+ * This function will give a free allocated irq to a client device.
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+ * That irq can then be caused to 'fire' by using the associated sysfs file.
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+ */
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+int iio_dummy_evgen_get_irq(void)
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+{
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+ int i, ret = 0;
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+ mutex_lock(&iio_evgen->lock);
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+ for (i = 0; i < IIO_EVENTGEN_NO; i++)
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+ if (iio_evgen->inuse[i] == false) {
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+ ret = iio_evgen->base + i;
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+ iio_evgen->inuse[i] = true;
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+ break;
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+ }
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+ mutex_unlock(&iio_evgen->lock);
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+ if (i == IIO_EVENTGEN_NO)
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+ return -ENOMEM;
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+ return ret;
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+}
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+EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);
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+
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+/**
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+ * iio_dummy_evgen_release_irq() - give the irq back.
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+ * @irq: irq being returned to the pool
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+ *
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+ * Used by client driver instances to give the irqs back when they disconnect
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+ */
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+int iio_dummy_evgen_release_irq(int irq)
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+{
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+ mutex_lock(&iio_evgen->lock);
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+ iio_evgen->inuse[irq - iio_evgen->base] = false;
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+ mutex_unlock(&iio_evgen->lock);
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+
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+ return 0;
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+}
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+EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
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+
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+static void iio_dummy_evgen_free(void)
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+{
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+ irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO);
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+ kfree(iio_evgen);
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+}
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+
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+static void iio_evgen_release(struct device *dev)
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+{
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+ iio_dummy_evgen_free();
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+}
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+
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+static ssize_t iio_evgen_poke(struct device *dev,
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+ struct device_attribute *attr,
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+ const char *buf,
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+ size_t len)
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+{
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+ struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
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+
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+ if (iio_evgen->enabled[this_attr->address])
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+ handle_nested_irq(iio_evgen->base + this_attr->address);
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+
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+ return len;
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+}
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+
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+static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
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+static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
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+static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
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+static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
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+static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
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+static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
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+static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
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+static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
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+static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
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+static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
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+
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+static struct attribute *iio_evgen_attrs[] = {
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+ &iio_dev_attr_poke_ev0.dev_attr.attr,
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+ &iio_dev_attr_poke_ev1.dev_attr.attr,
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+ &iio_dev_attr_poke_ev2.dev_attr.attr,
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+ &iio_dev_attr_poke_ev3.dev_attr.attr,
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+ &iio_dev_attr_poke_ev4.dev_attr.attr,
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+ &iio_dev_attr_poke_ev5.dev_attr.attr,
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+ &iio_dev_attr_poke_ev6.dev_attr.attr,
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+ &iio_dev_attr_poke_ev7.dev_attr.attr,
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+ &iio_dev_attr_poke_ev8.dev_attr.attr,
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+ &iio_dev_attr_poke_ev9.dev_attr.attr,
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+ NULL,
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+};
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+
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+static const struct attribute_group iio_evgen_group = {
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+ .attrs = iio_evgen_attrs,
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+};
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+
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+static const struct attribute_group *iio_evgen_groups[] = {
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+ &iio_evgen_group,
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+ NULL
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+};
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+
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+static struct device iio_evgen_dev = {
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+ .bus = &iio_bus_type,
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+ .groups = iio_evgen_groups,
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+ .release = &iio_evgen_release,
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+};
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+static __init int iio_dummy_evgen_init(void)
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+{
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+ int ret = iio_dummy_evgen_create();
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+ if (ret < 0)
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+ return ret;
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+ device_initialize(&iio_evgen_dev);
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+ dev_set_name(&iio_evgen_dev, "iio_evgen");
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+ return device_add(&iio_evgen_dev);
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+}
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+module_init(iio_dummy_evgen_init);
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+
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+static __exit void iio_dummy_evgen_exit(void)
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+{
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+ device_unregister(&iio_evgen_dev);
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+}
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+module_exit(iio_dummy_evgen_exit);
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+
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+MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
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+MODULE_DESCRIPTION("IIO dummy driver");
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+MODULE_LICENSE("GPL v2");
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Jonathan Cameron