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_work.h>
  28
  29/* Fiddly bit of faking and irq without hardware */
  30#define IIO_EVENTGEN_NO 10
  31
  32/**
  33 * struct iio_dummy_handle_irq - helper struct to simulate interrupt generation
  34 * @work: irq_work used to run handlers from hardirq context
  35 * @irq: fake irq line number to trigger an interrupt
  36 */
  37struct iio_dummy_handle_irq {
  38        struct irq_work work;
  39        int irq;
  40};
  41
  42/**
  43 * struct iio_dummy_evgen - evgen state
  44 * @chip: irq chip we are faking
  45 * @base: base of irq range
  46 * @enabled: mask of which irqs are enabled
  47 * @inuse: mask of which irqs are connected
  48 * @regs: irq regs we are faking
  49 * @lock: protect the evgen state
  50 * @handler: helper for a 'hardware-like' interrupt simulation
  51 */
  52struct iio_dummy_eventgen {
  53        struct irq_chip chip;
  54        int base;
  55        bool enabled[IIO_EVENTGEN_NO];
  56        bool inuse[IIO_EVENTGEN_NO];
  57        struct iio_dummy_regs regs[IIO_EVENTGEN_NO];
  58        struct mutex lock;
  59        struct iio_dummy_handle_irq handler;
  60};
  61
  62/* We can only ever have one instance of this 'device' */
  63static struct iio_dummy_eventgen *iio_evgen;
  64static const char *iio_evgen_name = "iio_dummy_evgen";
  65
  66static void iio_dummy_event_irqmask(struct irq_data *d)
  67{
  68        struct irq_chip *chip = irq_data_get_irq_chip(d);
  69        struct iio_dummy_eventgen *evgen =
  70                container_of(chip, struct iio_dummy_eventgen, chip);
  71
  72        evgen->enabled[d->irq - evgen->base] = false;
  73}
  74
  75static void iio_dummy_event_irqunmask(struct irq_data *d)
  76{
  77        struct irq_chip *chip = irq_data_get_irq_chip(d);
  78        struct iio_dummy_eventgen *evgen =
  79                container_of(chip, struct iio_dummy_eventgen, chip);
  80
  81        evgen->enabled[d->irq - evgen->base] = true;
  82}
  83
  84static void iio_dummy_work_handler(struct irq_work *work)
  85{
  86        struct iio_dummy_handle_irq *irq_handler;
  87
  88        irq_handler = container_of(work, struct iio_dummy_handle_irq, work);
  89        handle_simple_irq(irq_to_desc(irq_handler->irq));
  90}
  91
  92static int iio_dummy_evgen_create(void)
  93{
  94        int ret, i;
  95
  96        iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
  97        if (!iio_evgen)
  98                return -ENOMEM;
  99
 100        iio_evgen->base = irq_alloc_descs(-1, 0, IIO_EVENTGEN_NO, 0);
 101        if (iio_evgen->base < 0) {
 102                ret = iio_evgen->base;
 103                kfree(iio_evgen);
 104                return ret;
 105        }
 106        iio_evgen->chip.name = iio_evgen_name;
 107        iio_evgen->chip.irq_mask = &iio_dummy_event_irqmask;
 108        iio_evgen->chip.irq_unmask = &iio_dummy_event_irqunmask;
 109        for (i = 0; i < IIO_EVENTGEN_NO; i++) {
 110                irq_set_chip(iio_evgen->base + i, &iio_evgen->chip);
 111                irq_set_handler(iio_evgen->base + i, &handle_simple_irq);
 112                irq_modify_status(iio_evgen->base + i,
 113                                  IRQ_NOREQUEST | IRQ_NOAUTOEN,
 114                                  IRQ_NOPROBE);
 115        }
 116        init_irq_work(&iio_evgen->handler.work, iio_dummy_work_handler);
 117        mutex_init(&iio_evgen->lock);
 118        return 0;
 119}
 120
 121/**
 122 * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device
 123 *
 124 * This function will give a free allocated irq to a client device.
 125 * That irq can then be caused to 'fire' by using the associated sysfs file.
 126 */
 127int iio_dummy_evgen_get_irq(void)
 128{
 129        int i, ret = 0;
 130
 131        if (!iio_evgen)
 132                return -ENODEV;
 133
 134        mutex_lock(&iio_evgen->lock);
 135        for (i = 0; i < IIO_EVENTGEN_NO; i++)
 136                if (!iio_evgen->inuse[i]) {
 137                        ret = iio_evgen->base + i;
 138                        iio_evgen->inuse[i] = true;
 139                        break;
 140                }
 141        mutex_unlock(&iio_evgen->lock);
 142        if (i == IIO_EVENTGEN_NO)
 143                return -ENOMEM;
 144        return ret;
 145}
 146EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);
 147
 148/**
 149 * iio_dummy_evgen_release_irq() - give the irq back.
 150 * @irq: irq being returned to the pool
 151 *
 152 * Used by client driver instances to give the irqs back when they disconnect
 153 */
 154void iio_dummy_evgen_release_irq(int irq)
 155{
 156        mutex_lock(&iio_evgen->lock);
 157        iio_evgen->inuse[irq - iio_evgen->base] = false;
 158        mutex_unlock(&iio_evgen->lock);
 159}
 160EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
 161
 162struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq)
 163{
 164        return &iio_evgen->regs[irq - iio_evgen->base];
 165}
 166EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
 167
 168static void iio_dummy_evgen_free(void)
 169{
 170        irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO);
 171        kfree(iio_evgen);
 172}
 173
 174static void iio_evgen_release(struct device *dev)
 175{
 176        iio_dummy_evgen_free();
 177}
 178
 179static ssize_t iio_evgen_poke(struct device *dev,
 180                              struct device_attribute *attr,
 181                              const char *buf,
 182                              size_t len)
 183{
 184        struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 185        unsigned long event;
 186        int ret;
 187
 188        ret = kstrtoul(buf, 10, &event);
 189        if (ret)
 190                return ret;
 191
 192        iio_evgen->regs[this_attr->address].reg_id   = this_attr->address;
 193        iio_evgen->regs[this_attr->address].reg_data = event;
 194
 195        iio_evgen->handler.irq = iio_evgen->base + this_attr->address;
 196        if (iio_evgen->enabled[this_attr->address])
 197                irq_work_queue(&iio_evgen->handler.work);
 198
 199        return len;
 200}
 201
 202static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
 203static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
 204static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
 205static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
 206static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
 207static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
 208static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
 209static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
 210static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
 211static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
 212
 213static struct attribute *iio_evgen_attrs[] = {
 214        &iio_dev_attr_poke_ev0.dev_attr.attr,
 215        &iio_dev_attr_poke_ev1.dev_attr.attr,
 216        &iio_dev_attr_poke_ev2.dev_attr.attr,
 217        &iio_dev_attr_poke_ev3.dev_attr.attr,
 218        &iio_dev_attr_poke_ev4.dev_attr.attr,
 219        &iio_dev_attr_poke_ev5.dev_attr.attr,
 220        &iio_dev_attr_poke_ev6.dev_attr.attr,
 221        &iio_dev_attr_poke_ev7.dev_attr.attr,
 222        &iio_dev_attr_poke_ev8.dev_attr.attr,
 223        &iio_dev_attr_poke_ev9.dev_attr.attr,
 224        NULL,
 225};
 226
 227static const struct attribute_group iio_evgen_group = {
 228        .attrs = iio_evgen_attrs,
 229};
 230
 231static const struct attribute_group *iio_evgen_groups[] = {
 232        &iio_evgen_group,
 233        NULL
 234};
 235
 236static struct device iio_evgen_dev = {
 237        .bus = &iio_bus_type,
 238        .groups = iio_evgen_groups,
 239        .release = &iio_evgen_release,
 240};
 241
 242static __init int iio_dummy_evgen_init(void)
 243{
 244        int ret = iio_dummy_evgen_create();
 245
 246        if (ret < 0)
 247                return ret;
 248        device_initialize(&iio_evgen_dev);
 249        dev_set_name(&iio_evgen_dev, "iio_evgen");
 250        return device_add(&iio_evgen_dev);
 251}
 252module_init(iio_dummy_evgen_init);
 253
 254static __exit void iio_dummy_evgen_exit(void)
 255{
 256        device_unregister(&iio_evgen_dev);
 257}
 258module_exit(iio_dummy_evgen_exit);
 259
 260MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 261MODULE_DESCRIPTION("IIO dummy driver");
 262MODULE_LICENSE("GPL v2");
 263