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 * @lock: protect the evgen state
37 */
38struct 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' */
47static struct iio_dummy_eventgen *iio_evgen;
48static const char *iio_evgen_name = "iio_dummy_evgen";
49
50static 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
59static 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
68static 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 */
102int 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]) {
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}
121EXPORT_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 */
129int 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}
137EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
138
139static void iio_dummy_evgen_free(void)
140{
141	irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO);
142	kfree(iio_evgen);
143}
144
145static void iio_evgen_release(struct device *dev)
146{
147	iio_dummy_evgen_free();
148}
149
150static 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
163static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
164static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
165static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
166static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
167static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
168static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
169static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
170static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
171static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
172static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
173
174static 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
188static const struct attribute_group iio_evgen_group = {
189	.attrs = iio_evgen_attrs,
190};
191
192static const struct attribute_group *iio_evgen_groups[] = {
193	&iio_evgen_group,
194	NULL
195};
196
197static struct device iio_evgen_dev = {
198	.bus = &iio_bus_type,
199	.groups = iio_evgen_groups,
200	.release = &iio_evgen_release,
201};
202static __init int iio_dummy_evgen_init(void)
203{
204	int ret = iio_dummy_evgen_create();
205
206	if (ret < 0)
207		return ret;
208	device_initialize(&iio_evgen_dev);
209	dev_set_name(&iio_evgen_dev, "iio_evgen");
210	return device_add(&iio_evgen_dev);
211}
212module_init(iio_dummy_evgen_init);
213
214static __exit void iio_dummy_evgen_exit(void)
215{
216	device_unregister(&iio_evgen_dev);
217}
218module_exit(iio_dummy_evgen_exit);
219
220MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
221MODULE_DESCRIPTION("IIO dummy driver");
222MODULE_LICENSE("GPL v2");
223