drivers/iio/dummy/iio_dummy_evgen.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (c) 2011 Jonathan Cameron
   4  *
   5  * Companion module to the iio simple dummy example driver.
   6  * The purpose of this is to generate 'fake' event interrupts thus
   7  * allowing that driver's code to be as close as possible to that of
   8  * a normal driver talking to hardware.  The approach used here
   9  * is not intended to be general and just happens to work for this
  10  * particular use case.
  11  */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/slab.h>
  15 #include <linux/interrupt.h>
  16 #include <linux/irq.h>
  17 #include <linux/mutex.h>
  18 #include <linux/module.h>
  19 #include <linux/sysfs.h>
  20
  21 #include "iio_dummy_evgen.h"
  22 #include <linux/iio/iio.h>
  23 #include <linux/iio/sysfs.h>
  24 #include <linux/irq_sim.h>
  25
  26 /* Fiddly bit of faking and irq without hardware */
  27 #define IIO_EVENTGEN_NO 10
  28
  29 /**
  30  * struct iio_dummy_eventgen - event generator specific state
  31  * @regs: irq regs we are faking
  32  * @lock: protect the evgen state
  33  * @inuse: mask of which irqs are connected
  34  * @irq_sim: interrupt simulator
  35  * @base: base of irq range
  36  * @irq_sim_domain: irq simulator domain
  37  */
  38 struct iio_dummy_eventgen {
  39         struct iio_dummy_regs regs[IIO_EVENTGEN_NO];
  40         struct mutex lock;
  41         bool inuse[IIO_EVENTGEN_NO];
  42         struct irq_domain *irq_sim_domain;
  43 };
  44
  45 /* We can only ever have one instance of this 'device' */
  46 static struct iio_dummy_eventgen *iio_evgen;
  47
  48 static int iio_dummy_evgen_create(void)
  49 {
  50         int ret;
  51
  52         iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
  53         if (!iio_evgen)
  54                 return -ENOMEM;
  55
  56         iio_evgen->irq_sim_domain = irq_domain_create_sim(NULL,
  57                                                           IIO_EVENTGEN_NO);
  58         if (IS_ERR(iio_evgen->irq_sim_domain)) {
  59                 ret = PTR_ERR(iio_evgen->irq_sim_domain);
  60                 kfree(iio_evgen);
  61                 return ret;
  62         }
  63
  64         mutex_init(&iio_evgen->lock);
  65
  66         return 0;
  67 }
  68
  69 /**
  70  * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device
  71  *
  72  * This function will give a free allocated irq to a client device.
  73  * That irq can then be caused to 'fire' by using the associated sysfs file.
  74  */
  75 int iio_dummy_evgen_get_irq(void)
  76 {
  77         int i, ret = 0;
  78
  79         if (!iio_evgen)
  80                 return -ENODEV;
  81
  82         mutex_lock(&iio_evgen->lock);
  83         for (i = 0; i < IIO_EVENTGEN_NO; i++) {
  84                 if (!iio_evgen->inuse[i]) {
  85                         ret = irq_create_mapping(iio_evgen->irq_sim_domain, i);
  86                         iio_evgen->inuse[i] = true;
  87                         break;
  88                 }
  89         }
  90         mutex_unlock(&iio_evgen->lock);
  91         if (i == IIO_EVENTGEN_NO)
  92                 return -ENOMEM;
  93
  94         return ret;
  95 }
  96 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);
  97
  98 /**
  99  * iio_dummy_evgen_release_irq() - give the irq back.
 100  * @irq: irq being returned to the pool
 101  *
 102  * Used by client driver instances to give the irqs back when they disconnect
 103  */
 104 void iio_dummy_evgen_release_irq(int irq)
 105 {
 106         struct irq_data *irqd = irq_get_irq_data(irq);
 107
 108         mutex_lock(&iio_evgen->lock);
 109         iio_evgen->inuse[irqd_to_hwirq(irqd)] = false;
 110         irq_dispose_mapping(irq);
 111         mutex_unlock(&iio_evgen->lock);
 112 }
 113 EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
 114
 115 struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq)
 116 {
 117         struct irq_data *irqd = irq_get_irq_data(irq);
 118
 119         return &iio_evgen->regs[irqd_to_hwirq(irqd)];
 120
 121 }
 122 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
 123
 124 static void iio_dummy_evgen_free(void)
 125 {
 126         irq_domain_remove_sim(iio_evgen->irq_sim_domain);
 127         kfree(iio_evgen);
 128 }
 129
 130 static void iio_evgen_release(struct device *dev)
 131 {
 132         iio_dummy_evgen_free();
 133 }
 134
 135 static ssize_t iio_evgen_poke(struct device *dev,
 136                               struct device_attribute *attr,
 137                               const char *buf,
 138                               size_t len)
 139 {
 140         struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
 141         unsigned long event;
 142         int ret, irq;
 143
 144         ret = kstrtoul(buf, 10, &event);
 145         if (ret)
 146                 return ret;
 147
 148         iio_evgen->regs[this_attr->address].reg_id   = this_attr->address;
 149         iio_evgen->regs[this_attr->address].reg_data = event;
 150
 151         irq = irq_find_mapping(iio_evgen->irq_sim_domain, this_attr->address);
 152         ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true);
 153         if (ret)
 154                 return ret;
 155
 156         return len;
 157 }
 158
 159 static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
 160 static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
 161 static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
 162 static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
 163 static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
 164 static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
 165 static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
 166 static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
 167 static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
 168 static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
 169
 170 static struct attribute *iio_evgen_attrs[] = {
 171         &iio_dev_attr_poke_ev0.dev_attr.attr,
 172         &iio_dev_attr_poke_ev1.dev_attr.attr,
 173         &iio_dev_attr_poke_ev2.dev_attr.attr,
 174         &iio_dev_attr_poke_ev3.dev_attr.attr,
 175         &iio_dev_attr_poke_ev4.dev_attr.attr,
 176         &iio_dev_attr_poke_ev5.dev_attr.attr,
 177         &iio_dev_attr_poke_ev6.dev_attr.attr,
 178         &iio_dev_attr_poke_ev7.dev_attr.attr,
 179         &iio_dev_attr_poke_ev8.dev_attr.attr,
 180         &iio_dev_attr_poke_ev9.dev_attr.attr,
 181         NULL,
 182 };
 183
 184 static const struct attribute_group iio_evgen_group = {
 185         .attrs = iio_evgen_attrs,
 186 };
 187
 188 static const struct attribute_group *iio_evgen_groups[] = {
 189         &iio_evgen_group,
 190         NULL
 191 };
 192
 193 static struct device iio_evgen_dev = {
 194         .bus = &iio_bus_type,
 195         .groups = iio_evgen_groups,
 196         .release = &iio_evgen_release,
 197 };
 198
 199 static __init int iio_dummy_evgen_init(void)
 200 {
 201         int ret = iio_dummy_evgen_create();
 202
 203         if (ret < 0)
 204                 return ret;
 205         device_initialize(&iio_evgen_dev);
 206         dev_set_name(&iio_evgen_dev, "iio_evgen");
 207         ret = device_add(&iio_evgen_dev);
 208         if (ret)
 209                 put_device(&iio_evgen_dev);
 210         return ret;
 211 }
 212 module_init(iio_dummy_evgen_init);
 213
 214 static __exit void iio_dummy_evgen_exit(void)
 215 {
 216         device_unregister(&iio_evgen_dev);
 217 }
 218 module_exit(iio_dummy_evgen_exit);
 219
 220 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 221 MODULE_DESCRIPTION("IIO dummy driver");
 222 MODULE_LICENSE("GPL v2");