drivers/staging/iio/iio_dummy_evgen.c

   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  * @lock: protect the evgen state
  37  */
  38 struct iio_dummy_eventgen {
  39         struct irq_chip chip;
  40         int base;
  41         bool enabled[IIO_EVENTGEN_NO];
  42         bool inuse[IIO_EVENTGEN_NO];
  43         struct mutex lock;
  44 };
  45
  46 /* We can only ever have one instance of this 'device' */
  47 static struct iio_dummy_eventgen *iio_evgen;
  48 static const char *iio_evgen_name = "iio_dummy_evgen";
  49
  50 static void iio_dummy_event_irqmask(struct irq_data *d)
  51 {
  52         struct irq_chip *chip = irq_data_get_irq_chip(d);
  53         struct iio_dummy_eventgen *evgen =
  54                 container_of(chip, struct iio_dummy_eventgen, chip);
  55
  56         evgen->enabled[d->irq - evgen->base] = false;
  57 }
  58
  59 static void iio_dummy_event_irqunmask(struct irq_data *d)
  60 {
  61         struct irq_chip *chip = irq_data_get_irq_chip(d);
  62         struct iio_dummy_eventgen *evgen =
  63                 container_of(chip, struct iio_dummy_eventgen, chip);
  64
  65         evgen->enabled[d->irq - evgen->base] = true;
  66 }
  67
  68 static int iio_dummy_evgen_create(void)
  69 {
  70         int ret, i;
  71
  72         iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
  73         if (iio_evgen == NULL)
  74                 return -ENOMEM;
  75
  76         iio_evgen->base = irq_alloc_descs(-1, 0, IIO_EVENTGEN_NO, 0);
  77         if (iio_evgen->base < 0) {
  78                 ret = iio_evgen->base;
  79                 kfree(iio_evgen);
  80                 return ret;
  81         }
  82         iio_evgen->chip.name = iio_evgen_name;
  83         iio_evgen->chip.irq_mask = &iio_dummy_event_irqmask;
  84         iio_evgen->chip.irq_unmask = &iio_dummy_event_irqunmask;
  85         for (i = 0; i < IIO_EVENTGEN_NO; i++) {
  86                 irq_set_chip(iio_evgen->base + i, &iio_evgen->chip);
  87                 irq_set_handler(iio_evgen->base + i, &handle_simple_irq);
  88                 irq_modify_status(iio_evgen->base + i,
  89                                   IRQ_NOREQUEST | IRQ_NOAUTOEN,
  90                                   IRQ_NOPROBE);
  91         }
  92         mutex_init(&iio_evgen->lock);
  93         return 0;
  94 }
  95
  96 /**
  97  * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device
  98  *
  99  * This function will give a free allocated irq to a client device.
 100  * That irq can then be caused to 'fire' by using the associated sysfs file.
 101  */
 102 int iio_dummy_evgen_get_irq(void)
 103 {
 104         int i, ret = 0;
 105
 106         if (iio_evgen == NULL)
 107                 return -ENODEV;
 108
 109         mutex_lock(&iio_evgen->lock);
 110         for (i = 0; i < IIO_EVENTGEN_NO; i++)
 111                 if (!iio_evgen->inuse[i]) {
 112                         ret = iio_evgen->base + i;
 113                         iio_evgen->inuse[i] = true;
 114                         break;
 115                 }
 116         mutex_unlock(&iio_evgen->lock);
 117         if (i == IIO_EVENTGEN_NO)
 118                 return -ENOMEM;
 119         return ret;
 120 }
 121 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);
 122
 123 /**
 124  * iio_dummy_evgen_release_irq() - give the irq back.
 125  * @irq: irq being returned to the pool
 126  *
 127  * Used by client driver instances to give the irqs back when they disconnect
 128  */
 129 int iio_dummy_evgen_release_irq(int irq)
 130 {
 131         mutex_lock(&iio_evgen->lock);
 132         iio_evgen->inuse[irq - iio_evgen->base] = false;
 133         mutex_unlock(&iio_evgen->lock);
 134
 135         return 0;
 136 }
 137 EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
 138
 139 static void iio_dummy_evgen_free(void)
 140 {
 141         irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO);
 142         kfree(iio_evgen);
 143 }
 144
 145 static void iio_evgen_release(struct device *dev)
 146 {
 147         iio_dummy_evgen_free();
 148 }
 149
 150 static ssize_t iio_evgen_poke(struct device *dev,
 151                               struct device_attribute *attr,
 152                               const char *buf,
 153                               size_t len)
 154 {
 155         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 156
 157         if (iio_evgen->enabled[this_attr->address])
 158                 handle_nested_irq(iio_evgen->base + this_attr->address);
 159
 160         return len;
 161 }
 162
 163 static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
 164 static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
 165 static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
 166 static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
 167 static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
 168 static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
 169 static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
 170 static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
 171 static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
 172 static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
 173
 174 static struct attribute *iio_evgen_attrs[] = {
 175         &iio_dev_attr_poke_ev0.dev_attr.attr,
 176         &iio_dev_attr_poke_ev1.dev_attr.attr,
 177         &iio_dev_attr_poke_ev2.dev_attr.attr,
 178         &iio_dev_attr_poke_ev3.dev_attr.attr,
 179         &iio_dev_attr_poke_ev4.dev_attr.attr,
 180         &iio_dev_attr_poke_ev5.dev_attr.attr,
 181         &iio_dev_attr_poke_ev6.dev_attr.attr,
 182         &iio_dev_attr_poke_ev7.dev_attr.attr,
 183         &iio_dev_attr_poke_ev8.dev_attr.attr,
 184         &iio_dev_attr_poke_ev9.dev_attr.attr,
 185         NULL,
 186 };
 187
 188 static const struct attribute_group iio_evgen_group = {
 189         .attrs = iio_evgen_attrs,
 190 };
 191
 192 static const struct attribute_group *iio_evgen_groups[] = {
 193         &iio_evgen_group,
 194         NULL
 195 };
 196
 197 static struct device iio_evgen_dev = {
 198         .bus = &iio_bus_type,
 199         .groups = iio_evgen_groups,
 200         .release = &iio_evgen_release,
 201 };
 202 static __init int iio_dummy_evgen_init(void)
 203 {
 204         int ret = iio_dummy_evgen_create();
 205         if (ret < 0)
 206                 return ret;
 207         device_initialize(&iio_evgen_dev);
 208         dev_set_name(&iio_evgen_dev, "iio_evgen");
 209         return device_add(&iio_evgen_dev);
 210 }
 211 module_init(iio_dummy_evgen_init);
 212
 213 static __exit void iio_dummy_evgen_exit(void)
 214 {
 215         device_unregister(&iio_evgen_dev);
 216 }
 217 module_exit(iio_dummy_evgen_exit);
 218
 219 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 220 MODULE_DESCRIPTION("IIO dummy driver");
 221 MODULE_LICENSE("GPL v2");