drivers/iio/dummy/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 #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  */
  39 struct 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' */
  48 static struct iio_dummy_eventgen *iio_evgen;
  49
  50 static 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  */
  76 int 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 }
  97 EXPORT_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  */
 105 void 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 }
 111 EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
 112
 113 struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq)
 114 {
 115         return &iio_evgen->regs[irq - iio_evgen->base];
 116 }
 117 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
 118
 119 static void iio_dummy_evgen_free(void)
 120 {
 121         irq_sim_fini(&iio_evgen->irq_sim);
 122         kfree(iio_evgen);
 123 }
 124
 125 static void iio_evgen_release(struct device *dev)
 126 {
 127         iio_dummy_evgen_free();
 128 }
 129
 130 static 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
 151 static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
 152 static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
 153 static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
 154 static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
 155 static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
 156 static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
 157 static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
 158 static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
 159 static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
 160 static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
 161
 162 static 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
 176 static const struct attribute_group iio_evgen_group = {
 177         .attrs = iio_evgen_attrs,
 178 };
 179
 180 static const struct attribute_group *iio_evgen_groups[] = {
 181         &iio_evgen_group,
 182         NULL
 183 };
 184
 185 static struct device iio_evgen_dev = {
 186         .bus = &iio_bus_type,
 187         .groups = iio_evgen_groups,
 188         .release = &iio_evgen_release,
 189 };
 190
 191 static __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 }
 201 module_init(iio_dummy_evgen_init);
 202
 203 static __exit void iio_dummy_evgen_exit(void)
 204 {
 205         device_unregister(&iio_evgen_dev);
 206 }
 207 module_exit(iio_dummy_evgen_exit);
 208
 209 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 210 MODULE_DESCRIPTION("IIO dummy driver");
 211 MODULE_LICENSE("GPL v2");