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_work.h> 28 29 /* Fiddly bit of faking and irq without hardware */ 30 #define IIO_EVENTGEN_NO 10 31 32 /** 33 * struct iio_dummy_handle_irq - helper struct to simulate interrupt generation 34 * @work: irq_work used to run handlers from hardirq context 35 * @irq: fake irq line number to trigger an interrupt 36 */ 37 struct iio_dummy_handle_irq { 38 struct irq_work work; 39 int irq; 40 }; 41 42 /** 43 * struct iio_dummy_evgen - evgen state 44 * @chip: irq chip we are faking 45 * @base: base of irq range 46 * @enabled: mask of which irqs are enabled 47 * @inuse: mask of which irqs are connected 48 * @regs: irq regs we are faking 49 * @lock: protect the evgen state 50 * @handler: helper for a 'hardware-like' interrupt simulation 51 */ 52 struct iio_dummy_eventgen { 53 struct irq_chip chip; 54 int base; 55 bool enabled[IIO_EVENTGEN_NO]; 56 bool inuse[IIO_EVENTGEN_NO]; 57 struct iio_dummy_regs regs[IIO_EVENTGEN_NO]; 58 struct mutex lock; 59 struct iio_dummy_handle_irq handler; 60 }; 61 62 /* We can only ever have one instance of this 'device' */ 63 static struct iio_dummy_eventgen *iio_evgen; 64 static const char *iio_evgen_name = "iio_dummy_evgen"; 65 66 static void iio_dummy_event_irqmask(struct irq_data *d) 67 { 68 struct irq_chip *chip = irq_data_get_irq_chip(d); 69 struct iio_dummy_eventgen *evgen = 70 container_of(chip, struct iio_dummy_eventgen, chip); 71 72 evgen->enabled[d->irq - evgen->base] = false; 73 } 74 75 static void iio_dummy_event_irqunmask(struct irq_data *d) 76 { 77 struct irq_chip *chip = irq_data_get_irq_chip(d); 78 struct iio_dummy_eventgen *evgen = 79 container_of(chip, struct iio_dummy_eventgen, chip); 80 81 evgen->enabled[d->irq - evgen->base] = true; 82 } 83 84 static void iio_dummy_work_handler(struct irq_work *work) 85 { 86 struct iio_dummy_handle_irq *irq_handler; 87 88 irq_handler = container_of(work, struct iio_dummy_handle_irq, work); 89 handle_simple_irq(irq_to_desc(irq_handler->irq)); 90 } 91 92 static int iio_dummy_evgen_create(void) 93 { 94 int ret, i; 95 96 iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL); 97 if (!iio_evgen) 98 return -ENOMEM; 99 100 iio_evgen->base = irq_alloc_descs(-1, 0, IIO_EVENTGEN_NO, 0); 101 if (iio_evgen->base < 0) { 102 ret = iio_evgen->base; 103 kfree(iio_evgen); 104 return ret; 105 } 106 iio_evgen->chip.name = iio_evgen_name; 107 iio_evgen->chip.irq_mask = &iio_dummy_event_irqmask; 108 iio_evgen->chip.irq_unmask = &iio_dummy_event_irqunmask; 109 for (i = 0; i < IIO_EVENTGEN_NO; i++) { 110 irq_set_chip(iio_evgen->base + i, &iio_evgen->chip); 111 irq_set_handler(iio_evgen->base + i, &handle_simple_irq); 112 irq_modify_status(iio_evgen->base + i, 113 IRQ_NOREQUEST | IRQ_NOAUTOEN, 114 IRQ_NOPROBE); 115 } 116 init_irq_work(&iio_evgen->handler.work, iio_dummy_work_handler); 117 mutex_init(&iio_evgen->lock); 118 return 0; 119 } 120 121 /** 122 * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device 123 * 124 * This function will give a free allocated irq to a client device. 125 * That irq can then be caused to 'fire' by using the associated sysfs file. 126 */ 127 int iio_dummy_evgen_get_irq(void) 128 { 129 int i, ret = 0; 130 131 if (!iio_evgen) 132 return -ENODEV; 133 134 mutex_lock(&iio_evgen->lock); 135 for (i = 0; i < IIO_EVENTGEN_NO; i++) 136 if (!iio_evgen->inuse[i]) { 137 ret = iio_evgen->base + i; 138 iio_evgen->inuse[i] = true; 139 break; 140 } 141 mutex_unlock(&iio_evgen->lock); 142 if (i == IIO_EVENTGEN_NO) 143 return -ENOMEM; 144 return ret; 145 } 146 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq); 147 148 /** 149 * iio_dummy_evgen_release_irq() - give the irq back. 150 * @irq: irq being returned to the pool 151 * 152 * Used by client driver instances to give the irqs back when they disconnect 153 */ 154 void iio_dummy_evgen_release_irq(int irq) 155 { 156 mutex_lock(&iio_evgen->lock); 157 iio_evgen->inuse[irq - iio_evgen->base] = false; 158 mutex_unlock(&iio_evgen->lock); 159 } 160 EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq); 161 162 struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq) 163 { 164 return &iio_evgen->regs[irq - iio_evgen->base]; 165 } 166 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs); 167 168 static void iio_dummy_evgen_free(void) 169 { 170 irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO); 171 kfree(iio_evgen); 172 } 173 174 static void iio_evgen_release(struct device *dev) 175 { 176 iio_dummy_evgen_free(); 177 } 178 179 static ssize_t iio_evgen_poke(struct device *dev, 180 struct device_attribute *attr, 181 const char *buf, 182 size_t len) 183 { 184 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr); 185 unsigned long event; 186 int ret; 187 188 ret = kstrtoul(buf, 10, &event); 189 if (ret) 190 return ret; 191 192 iio_evgen->regs[this_attr->address].reg_id = this_attr->address; 193 iio_evgen->regs[this_attr->address].reg_data = event; 194 195 iio_evgen->handler.irq = iio_evgen->base + this_attr->address; 196 if (iio_evgen->enabled[this_attr->address]) 197 irq_work_queue(&iio_evgen->handler.work); 198 199 return len; 200 } 201 202 static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0); 203 static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1); 204 static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2); 205 static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3); 206 static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4); 207 static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5); 208 static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6); 209 static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7); 210 static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8); 211 static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9); 212 213 static struct attribute *iio_evgen_attrs[] = { 214 &iio_dev_attr_poke_ev0.dev_attr.attr, 215 &iio_dev_attr_poke_ev1.dev_attr.attr, 216 &iio_dev_attr_poke_ev2.dev_attr.attr, 217 &iio_dev_attr_poke_ev3.dev_attr.attr, 218 &iio_dev_attr_poke_ev4.dev_attr.attr, 219 &iio_dev_attr_poke_ev5.dev_attr.attr, 220 &iio_dev_attr_poke_ev6.dev_attr.attr, 221 &iio_dev_attr_poke_ev7.dev_attr.attr, 222 &iio_dev_attr_poke_ev8.dev_attr.attr, 223 &iio_dev_attr_poke_ev9.dev_attr.attr, 224 NULL, 225 }; 226 227 static const struct attribute_group iio_evgen_group = { 228 .attrs = iio_evgen_attrs, 229 }; 230 231 static const struct attribute_group *iio_evgen_groups[] = { 232 &iio_evgen_group, 233 NULL 234 }; 235 236 static struct device iio_evgen_dev = { 237 .bus = &iio_bus_type, 238 .groups = iio_evgen_groups, 239 .release = &iio_evgen_release, 240 }; 241 242 static __init int iio_dummy_evgen_init(void) 243 { 244 int ret = iio_dummy_evgen_create(); 245 246 if (ret < 0) 247 return ret; 248 device_initialize(&iio_evgen_dev); 249 dev_set_name(&iio_evgen_dev, "iio_evgen"); 250 return device_add(&iio_evgen_dev); 251 } 252 module_init(iio_dummy_evgen_init); 253 254 static __exit void iio_dummy_evgen_exit(void) 255 { 256 device_unregister(&iio_evgen_dev); 257 } 258 module_exit(iio_dummy_evgen_exit); 259 260 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>"); 261 MODULE_DESCRIPTION("IIO dummy driver"); 262 MODULE_LICENSE("GPL v2"); 263