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 "iio.h"
26 #include "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 actually have anyone connected
36 * @lock: protect the evgen state
37 */
38 struct 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' */
47 static struct iio_dummy_eventgen *iio_evgen;
48 static const char *iio_evgen_name = "iio_dummy_evgen";
49
iio_dummy_event_irqmask(struct irq_data * d)50 static 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
iio_dummy_event_irqunmask(struct irq_data * d)59 static 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
iio_dummy_evgen_create(void)68 static 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 */
iio_dummy_evgen_get_irq(void)102 int 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] == false) {
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 }
121 EXPORT_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 */
iio_dummy_evgen_release_irq(int irq)129 int 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 }
137 EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
138
iio_dummy_evgen_free(void)139 static void iio_dummy_evgen_free(void)
140 {
141 irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO);
142 kfree(iio_evgen);
143 }
144
iio_evgen_release(struct device * dev)145 static void iio_evgen_release(struct device *dev)
146 {
147 iio_dummy_evgen_free();
148 }
149
iio_evgen_poke(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)150 static 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
163 static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
164 static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
165 static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
166 static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
167 static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
168 static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
169 static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
170 static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
171 static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
172 static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
173
174 static 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
188 static const struct attribute_group iio_evgen_group = {
189 .attrs = iio_evgen_attrs,
190 };
191
192 static const struct attribute_group *iio_evgen_groups[] = {
193 &iio_evgen_group,
194 NULL
195 };
196
197 static struct device iio_evgen_dev = {
198 .bus = &iio_bus_type,
199 .groups = iio_evgen_groups,
200 .release = &iio_evgen_release,
201 };
iio_dummy_evgen_init(void)202 static __init int iio_dummy_evgen_init(void)
203 {
204 int ret = iio_dummy_evgen_create();
205 if (ret < 0)
206 return ret;
207 device_initialize(&iio_evgen_dev);
208 dev_set_name(&iio_evgen_dev, "iio_evgen");
209 return device_add(&iio_evgen_dev);
210 }
211 module_init(iio_dummy_evgen_init);
212
iio_dummy_evgen_exit(void)213 static __exit void iio_dummy_evgen_exit(void)
214 {
215 device_unregister(&iio_evgen_dev);
216 }
217 module_exit(iio_dummy_evgen_exit);
218
219 MODULE_AUTHOR("Jonathan Cameron <jic23@cam.ac.uk>");
220 MODULE_DESCRIPTION("IIO dummy driver");
221 MODULE_LICENSE("GPL v2");
222