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_sim.h> 28 29 /* Fiddly bit of faking and irq without hardware */ 30 #define IIO_EVENTGEN_NO 10 31 32 /** 33 * @regs: irq regs we are faking 34 * @lock: protect the evgen state 35 * @inuse: mask of which irqs are connected 36 * @irq_sim: interrupt simulator 37 * @base: base of irq range 38 */ 39 struct iio_dummy_eventgen { 40 struct iio_dummy_regs regs[IIO_EVENTGEN_NO]; 41 struct mutex lock; 42 bool inuse[IIO_EVENTGEN_NO]; 43 struct irq_sim irq_sim; 44 int base; 45 }; 46 47 /* We can only ever have one instance of this 'device' */ 48 static struct iio_dummy_eventgen *iio_evgen; 49 50 static int iio_dummy_evgen_create(void) 51 { 52 int ret; 53 54 iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL); 55 if (!iio_evgen) 56 return -ENOMEM; 57 58 ret = irq_sim_init(&iio_evgen->irq_sim, IIO_EVENTGEN_NO); 59 if (ret < 0) { 60 kfree(iio_evgen); 61 return ret; 62 } 63 64 iio_evgen->base = irq_sim_irqnum(&iio_evgen->irq_sim, 0); 65 mutex_init(&iio_evgen->lock); 66 67 return 0; 68 } 69 70 /** 71 * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device 72 * 73 * This function will give a free allocated irq to a client device. 74 * That irq can then be caused to 'fire' by using the associated sysfs file. 75 */ 76 int iio_dummy_evgen_get_irq(void) 77 { 78 int i, ret = 0; 79 80 if (!iio_evgen) 81 return -ENODEV; 82 83 mutex_lock(&iio_evgen->lock); 84 for (i = 0; i < IIO_EVENTGEN_NO; i++) { 85 if (!iio_evgen->inuse[i]) { 86 ret = irq_sim_irqnum(&iio_evgen->irq_sim, i); 87 iio_evgen->inuse[i] = true; 88 break; 89 } 90 } 91 mutex_unlock(&iio_evgen->lock); 92 if (i == IIO_EVENTGEN_NO) 93 return -ENOMEM; 94 95 return ret; 96 } 97 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq); 98 99 /** 100 * iio_dummy_evgen_release_irq() - give the irq back. 101 * @irq: irq being returned to the pool 102 * 103 * Used by client driver instances to give the irqs back when they disconnect 104 */ 105 void iio_dummy_evgen_release_irq(int irq) 106 { 107 mutex_lock(&iio_evgen->lock); 108 iio_evgen->inuse[irq - iio_evgen->base] = false; 109 mutex_unlock(&iio_evgen->lock); 110 } 111 EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq); 112 113 struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq) 114 { 115 return &iio_evgen->regs[irq - iio_evgen->base]; 116 } 117 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs); 118 119 static void iio_dummy_evgen_free(void) 120 { 121 irq_sim_fini(&iio_evgen->irq_sim); 122 kfree(iio_evgen); 123 } 124 125 static void iio_evgen_release(struct device *dev) 126 { 127 iio_dummy_evgen_free(); 128 } 129 130 static ssize_t iio_evgen_poke(struct device *dev, 131 struct device_attribute *attr, 132 const char *buf, 133 size_t len) 134 { 135 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr); 136 unsigned long event; 137 int ret; 138 139 ret = kstrtoul(buf, 10, &event); 140 if (ret) 141 return ret; 142 143 iio_evgen->regs[this_attr->address].reg_id = this_attr->address; 144 iio_evgen->regs[this_attr->address].reg_data = event; 145 146 irq_sim_fire(&iio_evgen->irq_sim, this_attr->address); 147 148 return len; 149 } 150 151 static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0); 152 static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1); 153 static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2); 154 static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3); 155 static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4); 156 static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5); 157 static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6); 158 static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7); 159 static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8); 160 static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9); 161 162 static struct attribute *iio_evgen_attrs[] = { 163 &iio_dev_attr_poke_ev0.dev_attr.attr, 164 &iio_dev_attr_poke_ev1.dev_attr.attr, 165 &iio_dev_attr_poke_ev2.dev_attr.attr, 166 &iio_dev_attr_poke_ev3.dev_attr.attr, 167 &iio_dev_attr_poke_ev4.dev_attr.attr, 168 &iio_dev_attr_poke_ev5.dev_attr.attr, 169 &iio_dev_attr_poke_ev6.dev_attr.attr, 170 &iio_dev_attr_poke_ev7.dev_attr.attr, 171 &iio_dev_attr_poke_ev8.dev_attr.attr, 172 &iio_dev_attr_poke_ev9.dev_attr.attr, 173 NULL, 174 }; 175 176 static const struct attribute_group iio_evgen_group = { 177 .attrs = iio_evgen_attrs, 178 }; 179 180 static const struct attribute_group *iio_evgen_groups[] = { 181 &iio_evgen_group, 182 NULL 183 }; 184 185 static struct device iio_evgen_dev = { 186 .bus = &iio_bus_type, 187 .groups = iio_evgen_groups, 188 .release = &iio_evgen_release, 189 }; 190 191 static __init int iio_dummy_evgen_init(void) 192 { 193 int ret = iio_dummy_evgen_create(); 194 195 if (ret < 0) 196 return ret; 197 device_initialize(&iio_evgen_dev); 198 dev_set_name(&iio_evgen_dev, "iio_evgen"); 199 return device_add(&iio_evgen_dev); 200 } 201 module_init(iio_dummy_evgen_init); 202 203 static __exit void iio_dummy_evgen_exit(void) 204 { 205 device_unregister(&iio_evgen_dev); 206 } 207 module_exit(iio_dummy_evgen_exit); 208 209 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>"); 210 MODULE_DESCRIPTION("IIO dummy driver"); 211 MODULE_LICENSE("GPL v2"); 212