LXR linux/drivers/iio/dummy/iio_dummy

   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 */
  38struct 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' */
  46static struct iio_dummy_eventgen *iio_evgen;
  47
  48static 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 */
  75int 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}
  96EXPORT_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 */
 104void 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}
 113EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
 114
 115struct 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}
 122EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
 123
 124static void iio_dummy_evgen_free(void)
 125{
 126        irq_domain_remove_sim(iio_evgen->irq_sim_domain);
 127        kfree(iio_evgen);
 128}
 129
 130static void iio_evgen_release(struct device *dev)
 131{
 132        iio_dummy_evgen_free();
 133}
 134
 135static 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
 159static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
 160static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
 161static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
 162static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
 163static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
 164static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
 165static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
 166static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
 167static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
 168static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
 169
 170static 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
 184static const struct attribute_group iio_evgen_group = {
 185        .attrs = iio_evgen_attrs,
 186};
 187
 188static const struct attribute_group *iio_evgen_groups[] = {
 189        &iio_evgen_group,
 190        NULL
 191};
 192
 193static struct device iio_evgen_dev = {
 194        .bus = &iio_bus_type,
 195        .groups = iio_evgen_groups,
 196        .release = &iio_evgen_release,
 197};
 198
 199static __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}
 212module_init(iio_dummy_evgen_init);
 213
 214static __exit void iio_dummy_evgen_exit(void)
 215{
 216        device_unregister(&iio_evgen_dev);
 217}
 218module_exit(iio_dummy_evgen_exit);
 219
 220MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
 221MODULE_DESCRIPTION("IIO dummy driver");
 222MODULE_LICENSE("GPL v2");
 223