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_domain *irq_sim_domain; 41 }; 42 43 /* We can only ever have one instance of this 'device' */ 44 static struct iio_dummy_eventgen *iio_evgen; 45 46 static int iio_dummy_evgen_create(void) 47 { 48 int ret; 49 50 iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL); 51 if (!iio_evgen) 52 return -ENOMEM; 53 54 iio_evgen->irq_sim_domain = irq_domain_create_sim(NULL, 55 IIO_EVENTGEN_NO); 56 if (IS_ERR(iio_evgen->irq_sim_domain)) { 57 ret = PTR_ERR(iio_evgen->irq_sim_domain); 58 kfree(iio_evgen); 59 return ret; 60 } 61 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_create_mapping(iio_evgen->irq_sim_domain, 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 struct irq_data *irqd = irq_get_irq_data(irq); 105 106 mutex_lock(&iio_evgen->lock); 107 iio_evgen->inuse[irqd_to_hwirq(irqd)] = false; 108 irq_dispose_mapping(irq); 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 struct irq_data *irqd = irq_get_irq_data(irq); 116 117 return &iio_evgen->regs[irqd_to_hwirq(irqd)]; 118 119 } 120 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs); 121 122 static void iio_dummy_evgen_free(void) 123 { 124 irq_domain_remove_sim(iio_evgen->irq_sim_domain); 125 kfree(iio_evgen); 126 } 127 128 static void iio_evgen_release(struct device *dev) 129 { 130 iio_dummy_evgen_free(); 131 } 132 133 static ssize_t iio_evgen_poke(struct device *dev, 134 struct device_attribute *attr, 135 const char *buf, 136 size_t len) 137 { 138 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr); 139 unsigned long event; 140 int ret, irq; 141 142 ret = kstrtoul(buf, 10, &event); 143 if (ret) 144 return ret; 145 146 iio_evgen->regs[this_attr->address].reg_id = this_attr->address; 147 iio_evgen->regs[this_attr->address].reg_data = event; 148 149 irq = irq_find_mapping(iio_evgen->irq_sim_domain, this_attr->address); 150 ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true); 151 if (ret) 152 return ret; 153 154 return len; 155 } 156 157 static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0); 158 static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1); 159 static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2); 160 static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3); 161 static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4); 162 static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5); 163 static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6); 164 static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7); 165 static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8); 166 static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9); 167 168 static struct attribute *iio_evgen_attrs[] = { 169 &iio_dev_attr_poke_ev0.dev_attr.attr, 170 &iio_dev_attr_poke_ev1.dev_attr.attr, 171 &iio_dev_attr_poke_ev2.dev_attr.attr, 172 &iio_dev_attr_poke_ev3.dev_attr.attr, 173 &iio_dev_attr_poke_ev4.dev_attr.attr, 174 &iio_dev_attr_poke_ev5.dev_attr.attr, 175 &iio_dev_attr_poke_ev6.dev_attr.attr, 176 &iio_dev_attr_poke_ev7.dev_attr.attr, 177 &iio_dev_attr_poke_ev8.dev_attr.attr, 178 &iio_dev_attr_poke_ev9.dev_attr.attr, 179 NULL, 180 }; 181 182 static const struct attribute_group iio_evgen_group = { 183 .attrs = iio_evgen_attrs, 184 }; 185 186 static const struct attribute_group *iio_evgen_groups[] = { 187 &iio_evgen_group, 188 NULL 189 }; 190 191 static struct device iio_evgen_dev = { 192 .bus = &iio_bus_type, 193 .groups = iio_evgen_groups, 194 .release = &iio_evgen_release, 195 }; 196 197 static __init int iio_dummy_evgen_init(void) 198 { 199 int ret = iio_dummy_evgen_create(); 200 201 if (ret < 0) 202 return ret; 203 device_initialize(&iio_evgen_dev); 204 dev_set_name(&iio_evgen_dev, "iio_evgen"); 205 ret = device_add(&iio_evgen_dev); 206 if (ret) 207 put_device(&iio_evgen_dev); 208 return ret; 209 } 210 module_init(iio_dummy_evgen_init); 211 212 static __exit void iio_dummy_evgen_exit(void) 213 { 214 device_unregister(&iio_evgen_dev); 215 } 216 module_exit(iio_dummy_evgen_exit); 217 218 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>"); 219 MODULE_DESCRIPTION("IIO dummy driver"); 220 MODULE_LICENSE("GPL v2"); 221