aboutsummaryrefslogtreecommitdiff
path: root/drivers/iio/dummy/iio_dummy_evgen.c
blob: 9e83f348df51f6f609d0143ec5844950d5ee78cb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
/**
 * Copyright (c) 2011 Jonathan Cameron
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 *
 * Companion module to the iio simple dummy example driver.
 * The purpose of this is to generate 'fake' event interrupts thus
 * allowing that driver's code to be as close as possible to that of
 * a normal driver talking to hardware.  The approach used here
 * is not intended to be general and just happens to work for this
 * particular use case.
 */

#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/interrupt.h>
#include <linux/irq.h>
#include <linux/mutex.h>
#include <linux/module.h>
#include <linux/sysfs.h>

#include "iio_dummy_evgen.h"
#include <linux/iio/iio.h>
#include <linux/iio/sysfs.h>
#include <linux/irq_work.h>

/* Fiddly bit of faking and irq without hardware */
#define IIO_EVENTGEN_NO 10

/**
 * struct iio_dummy_handle_irq - helper struct to simulate interrupt generation
 * @work: irq_work used to run handlers from hardirq context
 * @irq: fake irq line number to trigger an interrupt
 */
struct iio_dummy_handle_irq {
	struct irq_work work;
	int irq;
};

/**
 * struct iio_dummy_evgen - evgen state
 * @chip: irq chip we are faking
 * @base: base of irq range
 * @enabled: mask of which irqs are enabled
 * @inuse: mask of which irqs are connected
 * @regs: irq regs we are faking
 * @lock: protect the evgen state
 * @handler: helper for a 'hardware-like' interrupt simulation
 */
struct iio_dummy_eventgen {
	struct irq_chip chip;
	int base;
	bool enabled[IIO_EVENTGEN_NO];
	bool inuse[IIO_EVENTGEN_NO];
	struct iio_dummy_regs regs[IIO_EVENTGEN_NO];
	struct mutex lock;
	struct iio_dummy_handle_irq handler;
};

/* We can only ever have one instance of this 'device' */
static struct iio_dummy_eventgen *iio_evgen;
static const char *iio_evgen_name = "iio_dummy_evgen";

static void iio_dummy_event_irqmask(struct irq_data *d)
{
	struct irq_chip *chip = irq_data_get_irq_chip(d);
	struct iio_dummy_eventgen *evgen =
		container_of(chip, struct iio_dummy_eventgen, chip);

	evgen->enabled[d->irq - evgen->base] = false;
}

static void iio_dummy_event_irqunmask(struct irq_data *d)
{
	struct irq_chip *chip = irq_data_get_irq_chip(d);
	struct iio_dummy_eventgen *evgen =
		container_of(chip, struct iio_dummy_eventgen, chip);

	evgen->enabled[d->irq - evgen->base] = true;
}

static void iio_dummy_work_handler(struct irq_work *work)
{
	struct iio_dummy_handle_irq *irq_handler;

	irq_handler = container_of(work, struct iio_dummy_handle_irq, work);
	handle_simple_irq(irq_to_desc(irq_handler->irq));
}

static int iio_dummy_evgen_create(void)
{
	int ret, i;

	iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
	if (!iio_evgen)
		return -ENOMEM;

	iio_evgen->base = irq_alloc_descs(-1, 0, IIO_EVENTGEN_NO, 0);
	if (iio_evgen->base < 0) {
		ret = iio_evgen->base;
		kfree(iio_evgen);
		return ret;
	}
	iio_evgen->chip.name = iio_evgen_name;
	iio_evgen->chip.irq_mask = &iio_dummy_event_irqmask;
	iio_evgen->chip.irq_unmask = &iio_dummy_event_irqunmask;
	for (i = 0; i < IIO_EVENTGEN_NO; i++) {
		irq_set_chip(iio_evgen->base + i, &iio_evgen->chip);
		irq_set_handler(iio_evgen->base + i, &handle_simple_irq);
		irq_modify_status(iio_evgen->base + i,
				  IRQ_NOREQUEST | IRQ_NOAUTOEN,
				  IRQ_NOPROBE);
	}
	init_irq_work(&iio_evgen->handler.work, iio_dummy_work_handler);
	mutex_init(&iio_evgen->lock);
	return 0;
}

/**
 * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device
 *
 * This function will give a free allocated irq to a client device.
 * That irq can then be caused to 'fire' by using the associated sysfs file.
 */
int iio_dummy_evgen_get_irq(void)
{
	int i, ret = 0;

	if (!iio_evgen)
		return -ENODEV;

	mutex_lock(&iio_evgen->lock);
	for (i = 0; i < IIO_EVENTGEN_NO; i++)
		if (!iio_evgen->inuse[i]) {
			ret = iio_evgen->base + i;
			iio_evgen->inuse[i] = true;
			break;
		}
	mutex_unlock(&iio_evgen->lock);
	if (i == IIO_EVENTGEN_NO)
		return -ENOMEM;
	return ret;
}
EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);

/**
 * iio_dummy_evgen_release_irq() - give the irq back.
 * @irq: irq being returned to the pool
 *
 * Used by client driver instances to give the irqs back when they disconnect
 */
void iio_dummy_evgen_release_irq(int irq)
{
	mutex_lock(&iio_evgen->lock);
	iio_evgen->inuse[irq - iio_evgen->base] = false;
	mutex_unlock(&iio_evgen->lock);
}
EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);

struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq)
{
	return &iio_evgen->regs[irq - iio_evgen->base];
}
EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);

static void iio_dummy_evgen_free(void)
{
	irq_free_descs(iio_evgen->base, IIO_EVENTGEN_NO);
	kfree(iio_evgen);
}

static void iio_evgen_release(struct device *dev)
{
	iio_dummy_evgen_free();
}

static ssize_t iio_evgen_poke(struct device *dev,
			      struct device_attribute *attr,
			      const char *buf,
			      size_t len)
{
	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
	unsigned long event;
	int ret;

	ret = kstrtoul(buf, 10, &event);
	if (ret)
		return ret;

	iio_evgen->regs[this_attr->address].reg_id   = this_attr->address;
	iio_evgen->regs[this_attr->address].reg_data = event;

	iio_evgen->handler.irq = iio_evgen->base + this_attr->address;
	if (iio_evgen->enabled[this_attr->address])
		irq_work_queue(&iio_evgen->handler.work);

	return len;
}

static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);

static struct attribute *iio_evgen_attrs[] = {
	&iio_dev_attr_poke_ev0.dev_attr.attr,
	&iio_dev_attr_poke_ev1.dev_attr.attr,
	&iio_dev_attr_poke_ev2.dev_attr.attr,
	&iio_dev_attr_poke_ev3.dev_attr.attr,
	&iio_dev_attr_poke_ev4.dev_attr.attr,
	&iio_dev_attr_poke_ev5.dev_attr.attr,
	&iio_dev_attr_poke_ev6.dev_attr.attr,
	&iio_dev_attr_poke_ev7.dev_attr.attr,
	&iio_dev_attr_poke_ev8.dev_attr.attr,
	&iio_dev_attr_poke_ev9.dev_attr.attr,
	NULL,
};

static const struct attribute_group iio_evgen_group = {
	.attrs = iio_evgen_attrs,
};

static const struct attribute_group *iio_evgen_groups[] = {
	&iio_evgen_group,
	NULL
};

static struct device iio_evgen_dev = {
	.bus = &iio_bus_type,
	.groups = iio_evgen_groups,
	.release = &iio_evgen_release,
};

static __init int iio_dummy_evgen_init(void)
{
	int ret = iio_dummy_evgen_create();

	if (ret < 0)
		return ret;
	device_initialize(&iio_evgen_dev);
	dev_set_name(&iio_evgen_dev, "iio_evgen");
	return device_add(&iio_evgen_dev);
}
module_init(iio_dummy_evgen_init);

static __exit void iio_dummy_evgen_exit(void)
{
	device_unregister(&iio_evgen_dev);
}
module_exit(iio_dummy_evgen_exit);

MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
MODULE_DESCRIPTION("IIO dummy driver");
MODULE_LICENSE("GPL v2");