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_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  */
  37 struct 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  */
  52 struct 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' */
  63 static struct iio_dummy_eventgen *iio_evgen;
  64 static const char *iio_evgen_name = "iio_dummy_evgen";
  65
  66 static 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
  75 static 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
  84 static 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
  92 static 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  */
 127 int 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 }
 146 EXPORT_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  */
 154 void 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 }
 160 EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
 161
 162 struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq)
 163 {
 164         return &iio_evgen->regs[irq - iio_evgen->base];
 165 }
 166 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
 167
 168 static void iio_dummy_evgen_free(void)
 169 {
 170         irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO);
 171         kfree(iio_evgen);
 172 }
 173
 174 static void iio_evgen_release(struct device *dev)
 175 {
 176         iio_dummy_evgen_free();
 177 }
 178
 179 static 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
 202 static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
 203 static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
 204 static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
 205 static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
 206 static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
 207 static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
 208 static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
 209 static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
 210 static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
 211 static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
 212
 213 static 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
 227 static const struct attribute_group iio_evgen_group = {
 228         .attrs = iio_evgen_attrs,
 229 };
 230
 231 static const struct attribute_group *iio_evgen_groups[] = {
 232         &iio_evgen_group,
 233         NULL
 234 };
 235
 236 static struct device iio_evgen_dev = {
 237         .bus = &iio_bus_type,
 238         .groups = iio_evgen_groups,
 239         .release = &iio_evgen_release,
 240 };
 241
 242 static __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 }
 252 module_init(iio_dummy_evgen_init);
 253
 254 static __exit void iio_dummy_evgen_exit(void)
 255 {
 256         device_unregister(&iio_evgen_dev);
 257 }
 258 module_exit(iio_dummy_evgen_exit);
 259
 260 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 261 MODULE_DESCRIPTION("IIO dummy driver");
 262 MODULE_LICENSE("GPL v2");