iio_dummy_evgen.c (5887B)
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");