LXR linux/drivers/staging/iio/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
  28/* Fiddly bit of faking and irq without hardware */
  29#define IIO_EVENTGEN_NO 10
  30/**
  31 * struct iio_dummy_evgen - evgen state
  32 * @chip: irq chip we are faking
  33 * @base: base of irq range
  34 * @enabled: mask of which irqs are enabled
  35 * @inuse: mask of which irqs are connected
  36 * @regs: irq regs we are faking
  37 * @lock: protect the evgen state
  38 */
  39struct iio_dummy_eventgen {
  40        struct irq_chip chip;
  41        int base;
  42        bool enabled[IIO_EVENTGEN_NO];
  43        bool inuse[IIO_EVENTGEN_NO];
  44        struct iio_dummy_regs regs[IIO_EVENTGEN_NO];
  45        struct mutex lock;
  46};
  47
  48/* We can only ever have one instance of this 'device' */
  49static struct iio_dummy_eventgen *iio_evgen;
  50static const char *iio_evgen_name = "iio_dummy_evgen";
  51
  52static void iio_dummy_event_irqmask(struct irq_data *d)
  53{
  54        struct irq_chip *chip = irq_data_get_irq_chip(d);
  55        struct iio_dummy_eventgen *evgen =
  56                container_of(chip, struct iio_dummy_eventgen, chip);
  57
  58        evgen->enabled[d->irq - evgen->base] = false;
  59}
  60
  61static void iio_dummy_event_irqunmask(struct irq_data *d)
  62{
  63        struct irq_chip *chip = irq_data_get_irq_chip(d);
  64        struct iio_dummy_eventgen *evgen =
  65                container_of(chip, struct iio_dummy_eventgen, chip);
  66
  67        evgen->enabled[d->irq - evgen->base] = true;
  68}
  69
  70static int iio_dummy_evgen_create(void)
  71{
  72        int ret, i;
  73
  74        iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
  75        if (iio_evgen == NULL)
  76                return -ENOMEM;
  77
  78        iio_evgen->base = irq_alloc_descs(-1, 0, IIO_EVENTGEN_NO, 0);
  79        if (iio_evgen->base < 0) {
  80                ret = iio_evgen->base;
  81                kfree(iio_evgen);
  82                return ret;
  83        }
  84        iio_evgen->chip.name = iio_evgen_name;
  85        iio_evgen->chip.irq_mask = &iio_dummy_event_irqmask;
  86        iio_evgen->chip.irq_unmask = &iio_dummy_event_irqunmask;
  87        for (i = 0; i < IIO_EVENTGEN_NO; i++) {
  88                irq_set_chip(iio_evgen->base + i, &iio_evgen->chip);
  89                irq_set_handler(iio_evgen->base + i, &handle_simple_irq);
  90                irq_modify_status(iio_evgen->base + i,
  91                                  IRQ_NOREQUEST | IRQ_NOAUTOEN,
  92                                  IRQ_NOPROBE);
  93        }
  94        mutex_init(&iio_evgen->lock);
  95        return 0;
  96}
  97
  98/**
  99 * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device
 100 *
 101 * This function will give a free allocated irq to a client device.
 102 * That irq can then be caused to 'fire' by using the associated sysfs file.
 103 */
 104int iio_dummy_evgen_get_irq(void)
 105{
 106        int i, ret = 0;
 107
 108        if (iio_evgen == NULL)
 109                return -ENODEV;
 110
 111        mutex_lock(&iio_evgen->lock);
 112        for (i = 0; i < IIO_EVENTGEN_NO; i++)
 113                if (!iio_evgen->inuse[i]) {
 114                        ret = iio_evgen->base + i;
 115                        iio_evgen->inuse[i] = true;
 116                        break;
 117                }
 118        mutex_unlock(&iio_evgen->lock);
 119        if (i == IIO_EVENTGEN_NO)
 120                return -ENOMEM;
 121        return ret;
 122}
 123EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);
 124
 125/**
 126 * iio_dummy_evgen_release_irq() - give the irq back.
 127 * @irq: irq being returned to the pool
 128 *
 129 * Used by client driver instances to give the irqs back when they disconnect
 130 */
 131int iio_dummy_evgen_release_irq(int irq)
 132{
 133        mutex_lock(&iio_evgen->lock);
 134        iio_evgen->inuse[irq - iio_evgen->base] = false;
 135        mutex_unlock(&iio_evgen->lock);
 136
 137        return 0;
 138}
 139EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
 140
 141struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq)
 142{
 143        return &iio_evgen->regs[irq - iio_evgen->base];
 144}
 145EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
 146
 147static void iio_dummy_evgen_free(void)
 148{
 149        irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO);
 150        kfree(iio_evgen);
 151}
 152
 153static void iio_evgen_release(struct device *dev)
 154{
 155        iio_dummy_evgen_free();
 156}
 157
 158static ssize_t iio_evgen_poke(struct device *dev,
 159                              struct device_attribute *attr,
 160                              const char *buf,
 161                              size_t len)
 162{
 163        struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 164        unsigned long event;
 165        int ret;
 166
 167        ret = kstrtoul(buf, 10, &event);
 168        if (ret)
 169                return ret;
 170
 171        iio_evgen->regs[this_attr->address].reg_id   = this_attr->address;
 172        iio_evgen->regs[this_attr->address].reg_data = event;
 173
 174        if (iio_evgen->enabled[this_attr->address])
 175                handle_nested_irq(iio_evgen->base + this_attr->address);
 176
 177        return len;
 178}
 179
 180static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
 181static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
 182static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
 183static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
 184static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
 185static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
 186static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
 187static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
 188static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
 189static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
 190
 191static struct attribute *iio_evgen_attrs[] = {
 192        &iio_dev_attr_poke_ev0.dev_attr.attr,
 193        &iio_dev_attr_poke_ev1.dev_attr.attr,
 194        &iio_dev_attr_poke_ev2.dev_attr.attr,
 195        &iio_dev_attr_poke_ev3.dev_attr.attr,
 196        &iio_dev_attr_poke_ev4.dev_attr.attr,
 197        &iio_dev_attr_poke_ev5.dev_attr.attr,
 198        &iio_dev_attr_poke_ev6.dev_attr.attr,
 199        &iio_dev_attr_poke_ev7.dev_attr.attr,
 200        &iio_dev_attr_poke_ev8.dev_attr.attr,
 201        &iio_dev_attr_poke_ev9.dev_attr.attr,
 202        NULL,
 203};
 204
 205static const struct attribute_group iio_evgen_group = {
 206        .attrs = iio_evgen_attrs,
 207};
 208
 209static const struct attribute_group *iio_evgen_groups[] = {
 210        &iio_evgen_group,
 211        NULL
 212};
 213
 214static struct device iio_evgen_dev = {
 215        .bus = &iio_bus_type,
 216        .groups = iio_evgen_groups,
 217        .release = &iio_evgen_release,
 218};
 219static __init int iio_dummy_evgen_init(void)
 220{
 221        int ret = iio_dummy_evgen_create();
 222
 223        if (ret < 0)
 224                return ret;
 225        device_initialize(&iio_evgen_dev);
 226        dev_set_name(&iio_evgen_dev, "iio_evgen");
 227        return device_add(&iio_evgen_dev);
 228}
 229module_init(iio_dummy_evgen_init);
 230
 231static __exit void iio_dummy_evgen_exit(void)
 232{
 233        device_unregister(&iio_evgen_dev);
 234}
 235module_exit(iio_dummy_evgen_exit);
 236
 237MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 238MODULE_DESCRIPTION("IIO dummy driver");
 239MODULE_LICENSE("GPL v2");
 240