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
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 are connected
36 * @regs: irq regs we are faking
37 * @lock: protect the evgen state
38 */
39 struct iio_dummy_eventgen {
40 struct irq_chip chip;
41 int base;
42 bool enabled[IIO_EVENTGEN_NO];
43 bool inuse[IIO_EVENTGEN_NO];
44 struct iio_dummy_regs regs[IIO_EVENTGEN_NO];
45 struct mutex lock;
46 };
47
48 /* We can only ever have one instance of this 'device' */
49 static struct iio_dummy_eventgen *iio_evgen;
50 static const char *iio_evgen_name = "iio_dummy_evgen";
51
iio_dummy_event_irqmask(struct irq_data * d)52 static void iio_dummy_event_irqmask(struct irq_data *d)
53 {
54 struct irq_chip *chip = irq_data_get_irq_chip(d);
55 struct iio_dummy_eventgen *evgen =
56 container_of(chip, struct iio_dummy_eventgen, chip);
57
58 evgen->enabled[d->irq - evgen->base] = false;
59 }
60
iio_dummy_event_irqunmask(struct irq_data * d)61 static void iio_dummy_event_irqunmask(struct irq_data *d)
62 {
63 struct irq_chip *chip = irq_data_get_irq_chip(d);
64 struct iio_dummy_eventgen *evgen =
65 container_of(chip, struct iio_dummy_eventgen, chip);
66
67 evgen->enabled[d->irq - evgen->base] = true;
68 }
69
iio_dummy_evgen_create(void)70 static int iio_dummy_evgen_create(void)
71 {
72 int ret, i;
73
74 iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
75 if (!iio_evgen)
76 return -ENOMEM;
77
78 iio_evgen->base = irq_alloc_descs(-1, 0, IIO_EVENTGEN_NO, 0);
79 if (iio_evgen->base < 0) {
80 ret = iio_evgen->base;
81 kfree(iio_evgen);
82 return ret;
83 }
84 iio_evgen->chip.name = iio_evgen_name;
85 iio_evgen->chip.irq_mask = &iio_dummy_event_irqmask;
86 iio_evgen->chip.irq_unmask = &iio_dummy_event_irqunmask;
87 for (i = 0; i < IIO_EVENTGEN_NO; i++) {
88 irq_set_chip(iio_evgen->base + i, &iio_evgen->chip);
89 irq_set_handler(iio_evgen->base + i, &handle_simple_irq);
90 irq_modify_status(iio_evgen->base + i,
91 IRQ_NOREQUEST | IRQ_NOAUTOEN,
92 IRQ_NOPROBE);
93 }
94 mutex_init(&iio_evgen->lock);
95 return 0;
96 }
97
98 /**
99 * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device
100 *
101 * This function will give a free allocated irq to a client device.
102 * That irq can then be caused to 'fire' by using the associated sysfs file.
103 */
iio_dummy_evgen_get_irq(void)104 int iio_dummy_evgen_get_irq(void)
105 {
106 int i, ret = 0;
107
108 if (!iio_evgen)
109 return -ENODEV;
110
111 mutex_lock(&iio_evgen->lock);
112 for (i = 0; i < IIO_EVENTGEN_NO; i++)
113 if (!iio_evgen->inuse[i]) {
114 ret = iio_evgen->base + i;
115 iio_evgen->inuse[i] = true;
116 break;
117 }
118 mutex_unlock(&iio_evgen->lock);
119 if (i == IIO_EVENTGEN_NO)
120 return -ENOMEM;
121 return ret;
122 }
123 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);
124
125 /**
126 * iio_dummy_evgen_release_irq() - give the irq back.
127 * @irq: irq being returned to the pool
128 *
129 * Used by client driver instances to give the irqs back when they disconnect
130 */
iio_dummy_evgen_release_irq(int irq)131 int iio_dummy_evgen_release_irq(int irq)
132 {
133 mutex_lock(&iio_evgen->lock);
134 iio_evgen->inuse[irq - iio_evgen->base] = false;
135 mutex_unlock(&iio_evgen->lock);
136
137 return 0;
138 }
139 EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
140
iio_dummy_evgen_get_regs(int irq)141 struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq)
142 {
143 return &iio_evgen->regs[irq - iio_evgen->base];
144 }
145 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
146
iio_dummy_evgen_free(void)147 static void iio_dummy_evgen_free(void)
148 {
149 irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO);
150 kfree(iio_evgen);
151 }
152
iio_evgen_release(struct device * dev)153 static void iio_evgen_release(struct device *dev)
154 {
155 iio_dummy_evgen_free();
156 }
157
iio_evgen_poke(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)158 static ssize_t iio_evgen_poke(struct device *dev,
159 struct device_attribute *attr,
160 const char *buf,
161 size_t len)
162 {
163 struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
164 unsigned long event;
165 int ret;
166
167 ret = kstrtoul(buf, 10, &event);
168 if (ret)
169 return ret;
170
171 iio_evgen->regs[this_attr->address].reg_id = this_attr->address;
172 iio_evgen->regs[this_attr->address].reg_data = event;
173
174 if (iio_evgen->enabled[this_attr->address])
175 handle_nested_irq(iio_evgen->base + this_attr->address);
176
177 return len;
178 }
179
180 static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
181 static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
182 static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
183 static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
184 static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
185 static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
186 static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
187 static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
188 static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
189 static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
190
191 static struct attribute *iio_evgen_attrs[] = {
192 &iio_dev_attr_poke_ev0.dev_attr.attr,
193 &iio_dev_attr_poke_ev1.dev_attr.attr,
194 &iio_dev_attr_poke_ev2.dev_attr.attr,
195 &iio_dev_attr_poke_ev3.dev_attr.attr,
196 &iio_dev_attr_poke_ev4.dev_attr.attr,
197 &iio_dev_attr_poke_ev5.dev_attr.attr,
198 &iio_dev_attr_poke_ev6.dev_attr.attr,
199 &iio_dev_attr_poke_ev7.dev_attr.attr,
200 &iio_dev_attr_poke_ev8.dev_attr.attr,
201 &iio_dev_attr_poke_ev9.dev_attr.attr,
202 NULL,
203 };
204
205 static const struct attribute_group iio_evgen_group = {
206 .attrs = iio_evgen_attrs,
207 };
208
209 static const struct attribute_group *iio_evgen_groups[] = {
210 &iio_evgen_group,
211 NULL
212 };
213
214 static struct device iio_evgen_dev = {
215 .bus = &iio_bus_type,
216 .groups = iio_evgen_groups,
217 .release = &iio_evgen_release,
218 };
iio_dummy_evgen_init(void)219 static __init int iio_dummy_evgen_init(void)
220 {
221 int ret = iio_dummy_evgen_create();
222
223 if (ret < 0)
224 return ret;
225 device_initialize(&iio_evgen_dev);
226 dev_set_name(&iio_evgen_dev, "iio_evgen");
227 return device_add(&iio_evgen_dev);
228 }
229 module_init(iio_dummy_evgen_init);
230
iio_dummy_evgen_exit(void)231 static __exit void iio_dummy_evgen_exit(void)
232 {
233 device_unregister(&iio_evgen_dev);
234 }
235 module_exit(iio_dummy_evgen_exit);
236
237 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
238 MODULE_DESCRIPTION("IIO dummy driver");
239 MODULE_LICENSE("GPL v2");
240