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 * @regs: irq regs we are faking 31 * @lock: protect the evgen state 32 * @inuse: mask of which irqs are connected 33 * @irq_sim: interrupt simulator 34 * @base: base of irq range 35 */ 36 struct iio_dummy_eventgen { 37 struct iio_dummy_regs regs[IIO_EVENTGEN_NO]; 38 struct mutex lock; 39 bool inuse[IIO_EVENTGEN_NO]; 40 struct irq_sim irq_sim; 41 int base; 42 }; 43 44 /* We can only ever have one instance of this 'device' */ 45 static struct iio_dummy_eventgen *iio_evgen; 46 47 static int iio_dummy_evgen_create(void) 48 { 49 int ret; 50 51 iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL); 52 if (!iio_evgen) 53 return -ENOMEM; 54 55 ret = irq_sim_init(&iio_evgen->irq_sim, IIO_EVENTGEN_NO); 56 if (ret < 0) { 57 kfree(iio_evgen); 58 return ret; 59 } 60 61 iio_evgen->base = irq_sim_irqnum(&iio_evgen->irq_sim, 0); 62 mutex_init(&iio_evgen->lock); 63 64 return 0; 65 } 66 67 /** 68 * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device 69 * 70 * This function will give a free allocated irq to a client device. 71 * That irq can then be caused to 'fire' by using the associated sysfs file. 72 */ 73 int iio_dummy_evgen_get_irq(void) 74 { 75 int i, ret = 0; 76 77 if (!iio_evgen) 78 return -ENODEV; 79 80 mutex_lock(&iio_evgen->lock); 81 for (i = 0; i < IIO_EVENTGEN_NO; i++) { 82 if (!iio_evgen->inuse[i]) { 83 ret = irq_sim_irqnum(&iio_evgen->irq_sim, i); 84 iio_evgen->inuse[i] = true; 85 break; 86 } 87 } 88 mutex_unlock(&iio_evgen->lock); 89 if (i == IIO_EVENTGEN_NO) 90 return -ENOMEM; 91 92 return ret; 93 } 94 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq); 95 96 /** 97 * iio_dummy_evgen_release_irq() - give the irq back. 98 * @irq: irq being returned to the pool 99 * 100 * Used by client driver instances to give the irqs back when they disconnect 101 */ 102 void iio_dummy_evgen_release_irq(int irq) 103 { 104 mutex_lock(&iio_evgen->lock); 105 iio_evgen->inuse[irq - iio_evgen->base] = false; 106 mutex_unlock(&iio_evgen->lock); 107 } 108 EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq); 109 110 struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq) 111 { 112 return &iio_evgen->regs[irq - iio_evgen->base]; 113 } 114 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs); 115 116 static void iio_dummy_evgen_free(void) 117 { 118 irq_sim_fini(&iio_evgen->irq_sim); 119 kfree(iio_evgen); 120 } 121 122 static void iio_evgen_release(struct device *dev) 123 { 124 iio_dummy_evgen_free(); 125 } 126 127 static ssize_t iio_evgen_poke(struct device *dev, 128 struct device_attribute *attr, 129 const char *buf, 130 size_t len) 131 { 132 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr); 133 unsigned long event; 134 int ret; 135 136 ret = kstrtoul(buf, 10, &event); 137 if (ret) 138 return ret; 139 140 iio_evgen->regs[this_attr->address].reg_id = this_attr->address; 141 iio_evgen->regs[this_attr->address].reg_data = event; 142 143 irq_sim_fire(&iio_evgen->irq_sim, this_attr->address); 144 145 return len; 146 } 147 148 static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0); 149 static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1); 150 static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2); 151 static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3); 152 static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4); 153 static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5); 154 static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6); 155 static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7); 156 static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8); 157 static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9); 158 159 static struct attribute *iio_evgen_attrs[] = { 160 &iio_dev_attr_poke_ev0.dev_attr.attr, 161 &iio_dev_attr_poke_ev1.dev_attr.attr, 162 &iio_dev_attr_poke_ev2.dev_attr.attr, 163 &iio_dev_attr_poke_ev3.dev_attr.attr, 164 &iio_dev_attr_poke_ev4.dev_attr.attr, 165 &iio_dev_attr_poke_ev5.dev_attr.attr, 166 &iio_dev_attr_poke_ev6.dev_attr.attr, 167 &iio_dev_attr_poke_ev7.dev_attr.attr, 168 &iio_dev_attr_poke_ev8.dev_attr.attr, 169 &iio_dev_attr_poke_ev9.dev_attr.attr, 170 NULL, 171 }; 172 173 static const struct attribute_group iio_evgen_group = { 174 .attrs = iio_evgen_attrs, 175 }; 176 177 static const struct attribute_group *iio_evgen_groups[] = { 178 &iio_evgen_group, 179 NULL 180 }; 181 182 static struct device iio_evgen_dev = { 183 .bus = &iio_bus_type, 184 .groups = iio_evgen_groups, 185 .release = &iio_evgen_release, 186 }; 187 188 static __init int iio_dummy_evgen_init(void) 189 { 190 int ret = iio_dummy_evgen_create(); 191 192 if (ret < 0) 193 return ret; 194 device_initialize(&iio_evgen_dev); 195 dev_set_name(&iio_evgen_dev, "iio_evgen"); 196 ret = device_add(&iio_evgen_dev); 197 if (ret) 198 put_device(&iio_evgen_dev); 199 return ret; 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