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 28/* Fiddly bit of faking and irq without hardware */ 29#define IIO_EVENTGEN_NO 10 30/** 31 * struct iio_dummy_evgen - evgen state 32 * @chip: irq chip we are faking 33 * @base: base of irq range 34 * @enabled: mask of which irqs are enabled 35 * @inuse: mask of which irqs are connected 36 * @lock: protect the evgen state 37 */ 38struct iio_dummy_eventgen { 39 struct irq_chip chip; 40 int base; 41 bool enabled[IIO_EVENTGEN_NO]; 42 bool inuse[IIO_EVENTGEN_NO]; 43 struct mutex lock; 44}; 45 46/* We can only ever have one instance of this 'device' */ 47static struct iio_dummy_eventgen *iio_evgen; 48static const char *iio_evgen_name = "iio_dummy_evgen"; 49 50static void iio_dummy_event_irqmask(struct irq_data *d) 51{ 52 struct irq_chip *chip = irq_data_get_irq_chip(d); 53 struct iio_dummy_eventgen *evgen = 54 container_of(chip, struct iio_dummy_eventgen, chip); 55 56 evgen->enabled[d->irq - evgen->base] = false; 57} 58 59static void iio_dummy_event_irqunmask(struct irq_data *d) 60{ 61 struct irq_chip *chip = irq_data_get_irq_chip(d); 62 struct iio_dummy_eventgen *evgen = 63 container_of(chip, struct iio_dummy_eventgen, chip); 64 65 evgen->enabled[d->irq - evgen->base] = true; 66} 67 68static int iio_dummy_evgen_create(void) 69{ 70 int ret, i; 71 72 iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL); 73 if (iio_evgen == NULL) 74 return -ENOMEM; 75 76 iio_evgen->base = irq_alloc_descs(-1, 0, IIO_EVENTGEN_NO, 0); 77 if (iio_evgen->base < 0) { 78 ret = iio_evgen->base; 79 kfree(iio_evgen); 80 return ret; 81 } 82 iio_evgen->chip.name = iio_evgen_name; 83 iio_evgen->chip.irq_mask = &iio_dummy_event_irqmask; 84 iio_evgen->chip.irq_unmask = &iio_dummy_event_irqunmask; 85 for (i = 0; i < IIO_EVENTGEN_NO; i++) { 86 irq_set_chip(iio_evgen->base + i, &iio_evgen->chip); 87 irq_set_handler(iio_evgen->base + i, &handle_simple_irq); 88 irq_modify_status(iio_evgen->base + i, 89 IRQ_NOREQUEST | IRQ_NOAUTOEN, 90 IRQ_NOPROBE); 91 } 92 mutex_init(&iio_evgen->lock); 93 return 0; 94} 95 96/** 97 * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device 98 * 99 * This function will give a free allocated irq to a client device. 100 * That irq can then be caused to 'fire' by using the associated sysfs file. 101 */ 102int iio_dummy_evgen_get_irq(void) 103{ 104 int i, ret = 0; 105 106 if (iio_evgen == NULL) 107 return -ENODEV; 108 109 mutex_lock(&iio_evgen->lock); 110 for (i = 0; i < IIO_EVENTGEN_NO; i++) 111 if (!iio_evgen->inuse[i]) { 112 ret = iio_evgen->base + i; 113 iio_evgen->inuse[i] = true; 114 break; 115 } 116 mutex_unlock(&iio_evgen->lock); 117 if (i == IIO_EVENTGEN_NO) 118 return -ENOMEM; 119 return ret; 120} 121EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq); 122 123/** 124 * iio_dummy_evgen_release_irq() - give the irq back. 125 * @irq: irq being returned to the pool 126 * 127 * Used by client driver instances to give the irqs back when they disconnect 128 */ 129int iio_dummy_evgen_release_irq(int irq) 130{ 131 mutex_lock(&iio_evgen->lock); 132 iio_evgen->inuse[irq - iio_evgen->base] = false; 133 mutex_unlock(&iio_evgen->lock); 134 135 return 0; 136} 137EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq); 138 139static void iio_dummy_evgen_free(void) 140{ 141 irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO); 142 kfree(iio_evgen); 143} 144 145static void iio_evgen_release(struct device *dev) 146{ 147 iio_dummy_evgen_free(); 148} 149 150static ssize_t iio_evgen_poke(struct device *dev, 151 struct device_attribute *attr, 152 const char *buf, 153 size_t len) 154{ 155 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr); 156 157 if (iio_evgen->enabled[this_attr->address]) 158 handle_nested_irq(iio_evgen->base + this_attr->address); 159 160 return len; 161} 162 163static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0); 164static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1); 165static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2); 166static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3); 167static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4); 168static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5); 169static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6); 170static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7); 171static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8); 172static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9); 173 174static struct attribute *iio_evgen_attrs[] = { 175 &iio_dev_attr_poke_ev0.dev_attr.attr, 176 &iio_dev_attr_poke_ev1.dev_attr.attr, 177 &iio_dev_attr_poke_ev2.dev_attr.attr, 178 &iio_dev_attr_poke_ev3.dev_attr.attr, 179 &iio_dev_attr_poke_ev4.dev_attr.attr, 180 &iio_dev_attr_poke_ev5.dev_attr.attr, 181 &iio_dev_attr_poke_ev6.dev_attr.attr, 182 &iio_dev_attr_poke_ev7.dev_attr.attr, 183 &iio_dev_attr_poke_ev8.dev_attr.attr, 184 &iio_dev_attr_poke_ev9.dev_attr.attr, 185 NULL, 186}; 187 188static const struct attribute_group iio_evgen_group = { 189 .attrs = iio_evgen_attrs, 190}; 191 192static const struct attribute_group *iio_evgen_groups[] = { 193 &iio_evgen_group, 194 NULL 195}; 196 197static struct device iio_evgen_dev = { 198 .bus = &iio_bus_type, 199 .groups = iio_evgen_groups, 200 .release = &iio_evgen_release, 201}; 202static __init int iio_dummy_evgen_init(void) 203{ 204 int ret = iio_dummy_evgen_create(); 205 206 if (ret < 0) 207 return ret; 208 device_initialize(&iio_evgen_dev); 209 dev_set_name(&iio_evgen_dev, "iio_evgen"); 210 return device_add(&iio_evgen_dev); 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