LXR linux/drivers/iio/dummy/iio_dummy

   1/**
   2 * Copyright (c) 2011 Jonathan Cameron
   3 *
   4 * This program is free software; you can redistribute it and/or modify it
   5 * under the terms of the GNU General Public License version 2 as published by
   6 * the Free Software Foundation.
   7 *
   8 * Companion module to the iio simple dummy example driver.
   9 * The purpose of this is to generate 'fake' event interrupts thus
  10 * allowing that driver's code to be as close as possible to that of
  11 * a normal driver talking to hardware.  The approach used here
  12 * is not intended to be general and just happens to work for this
  13 * particular use case.
  14 */
  15
  16#include <linux/kernel.h>
  17#include <linux/slab.h>
  18#include <linux/interrupt.h>
  19#include <linux/irq.h>
  20#include <linux/mutex.h>
  21#include <linux/module.h>
  22#include <linux/sysfs.h>
  23
  24#include "iio_dummy_evgen.h"
  25#include <linux/iio/iio.h>
  26#include <linux/iio/sysfs.h>
  27#include <linux/irq_sim.h>
  28
  29/* Fiddly bit of faking and irq without hardware */
  30#define IIO_EVENTGEN_NO 10
  31
  32/**
  33 * @regs: irq regs we are faking
  34 * @lock: protect the evgen state
  35 * @inuse: mask of which irqs are connected
  36 * @irq_sim: interrupt simulator
  37 * @base: base of irq range
  38 */
  39struct iio_dummy_eventgen {
  40        struct iio_dummy_regs regs[IIO_EVENTGEN_NO];
  41        struct mutex lock;
  42        bool inuse[IIO_EVENTGEN_NO];
  43        struct irq_sim irq_sim;
  44        int base;
  45};
  46
  47/* We can only ever have one instance of this 'device' */
  48static struct iio_dummy_eventgen *iio_evgen;
  49
  50static int iio_dummy_evgen_create(void)
  51{
  52        int ret;
  53
  54        iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
  55        if (!iio_evgen)
  56                return -ENOMEM;
  57
  58        ret = irq_sim_init(&iio_evgen->irq_sim, IIO_EVENTGEN_NO);
  59        if (ret < 0) {
  60                kfree(iio_evgen);
  61                return ret;
  62        }
  63
  64        iio_evgen->base = irq_sim_irqnum(&iio_evgen->irq_sim, 0);
  65        mutex_init(&iio_evgen->lock);
  66
  67        return 0;
  68}
  69
  70/**
  71 * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device
  72 *
  73 * This function will give a free allocated irq to a client device.
  74 * That irq can then be caused to 'fire' by using the associated sysfs file.
  75 */
  76int iio_dummy_evgen_get_irq(void)
  77{
  78        int i, ret = 0;
  79
  80        if (!iio_evgen)
  81                return -ENODEV;
  82
  83        mutex_lock(&iio_evgen->lock);
  84        for (i = 0; i < IIO_EVENTGEN_NO; i++) {
  85                if (!iio_evgen->inuse[i]) {
  86                        ret = irq_sim_irqnum(&iio_evgen->irq_sim, i);
  87                        iio_evgen->inuse[i] = true;
  88                        break;
  89                }
  90        }
  91        mutex_unlock(&iio_evgen->lock);
  92        if (i == IIO_EVENTGEN_NO)
  93                return -ENOMEM;
  94
  95        return ret;
  96}
  97EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);
  98
  99/**
 100 * iio_dummy_evgen_release_irq() - give the irq back.
 101 * @irq: irq being returned to the pool
 102 *
 103 * Used by client driver instances to give the irqs back when they disconnect
 104 */
 105void iio_dummy_evgen_release_irq(int irq)
 106{
 107        mutex_lock(&iio_evgen->lock);
 108        iio_evgen->inuse[irq - iio_evgen->base] = false;
 109        mutex_unlock(&iio_evgen->lock);
 110}
 111EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
 112
 113struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq)
 114{
 115        return &iio_evgen->regs[irq - iio_evgen->base];
 116}
 117EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
 118
 119static void iio_dummy_evgen_free(void)
 120{
 121        irq_sim_fini(&iio_evgen->irq_sim);
 122        kfree(iio_evgen);
 123}
 124
 125static void iio_evgen_release(struct device *dev)
 126{
 127        iio_dummy_evgen_free();
 128}
 129
 130static ssize_t iio_evgen_poke(struct device *dev,
 131                              struct device_attribute *attr,
 132                              const char *buf,
 133                              size_t len)
 134{
 135        struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 136        unsigned long event;
 137        int ret;
 138
 139        ret = kstrtoul(buf, 10, &event);
 140        if (ret)
 141                return ret;
 142
 143        iio_evgen->regs[this_attr->address].reg_id   = this_attr->address;
 144        iio_evgen->regs[this_attr->address].reg_data = event;
 145
 146        irq_sim_fire(&iio_evgen->irq_sim, this_attr->address);
 147
 148        return len;
 149}
 150
 151static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
 152static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
 153static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
 154static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
 155static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
 156static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
 157static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
 158static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
 159static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
 160static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
 161
 162static struct attribute *iio_evgen_attrs[] = {
 163        &iio_dev_attr_poke_ev0.dev_attr.attr,
 164        &iio_dev_attr_poke_ev1.dev_attr.attr,
 165        &iio_dev_attr_poke_ev2.dev_attr.attr,
 166        &iio_dev_attr_poke_ev3.dev_attr.attr,
 167        &iio_dev_attr_poke_ev4.dev_attr.attr,
 168        &iio_dev_attr_poke_ev5.dev_attr.attr,
 169        &iio_dev_attr_poke_ev6.dev_attr.attr,
 170        &iio_dev_attr_poke_ev7.dev_attr.attr,
 171        &iio_dev_attr_poke_ev8.dev_attr.attr,
 172        &iio_dev_attr_poke_ev9.dev_attr.attr,
 173        NULL,
 174};
 175
 176static const struct attribute_group iio_evgen_group = {
 177        .attrs = iio_evgen_attrs,
 178};
 179
 180static const struct attribute_group *iio_evgen_groups[] = {
 181        &iio_evgen_group,
 182        NULL
 183};
 184
 185static struct device iio_evgen_dev = {
 186        .bus = &iio_bus_type,
 187        .groups = iio_evgen_groups,
 188        .release = &iio_evgen_release,
 189};
 190
 191static __init int iio_dummy_evgen_init(void)
 192{
 193        int ret = iio_dummy_evgen_create();
 194
 195        if (ret < 0)
 196                return ret;
 197        device_initialize(&iio_evgen_dev);
 198        dev_set_name(&iio_evgen_dev, "iio_evgen");
 199        return device_add(&iio_evgen_dev);
 200}
 201module_init(iio_dummy_evgen_init);
 202
 203static __exit void iio_dummy_evgen_exit(void)
 204{
 205        device_unregister(&iio_evgen_dev);
 206}
 207module_exit(iio_dummy_evgen_exit);
 208
 209MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 210MODULE_DESCRIPTION("IIO dummy driver");
 211MODULE_LICENSE("GPL v2");
 212