iio_dummy_evgen.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright (c) 2011 Jonathan Cameron
  4 *
  5 * Companion module to the iio simple dummy example driver.
  6 * The purpose of this is to generate 'fake' event interrupts thus
  7 * allowing that driver's code to be as close as possible to that of
  8 * a normal driver talking to hardware.  The approach used here
  9 * is not intended to be general and just happens to work for this
 10 * particular use case.
 11 */
 12
 13#include <linux/kernel.h>
 14#include <linux/slab.h>
 15#include <linux/interrupt.h>
 16#include <linux/irq.h>
 17#include <linux/mutex.h>
 18#include <linux/module.h>
 19#include <linux/sysfs.h>
 20
 21#include "iio_dummy_evgen.h"
 22#include <linux/iio/iio.h>
 23#include <linux/iio/sysfs.h>
 24#include <linux/irq_sim.h>
 25
 26/* Fiddly bit of faking and irq without hardware */
 27#define IIO_EVENTGEN_NO 10
 28
 29/**
 30 * struct iio_dummy_eventgen - event generator specific state
 31 * @regs: irq regs we are faking
 32 * @lock: protect the evgen state
 33 * @inuse: mask of which irqs are connected
 34 * @irq_sim_domain: irq simulator domain
 35 */
 36struct iio_dummy_eventgen {
 37	struct iio_dummy_regs regs[IIO_EVENTGEN_NO];
 38	struct mutex lock;
 39	bool inuse[IIO_EVENTGEN_NO];
 40	struct irq_domain *irq_sim_domain;
 41};
 42
 43/* We can only ever have one instance of this 'device' */
 44static struct iio_dummy_eventgen *iio_evgen;
 45
 46static int iio_dummy_evgen_create(void)
 47{
 48	int ret;
 49
 50	iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
 51	if (!iio_evgen)
 52		return -ENOMEM;
 53
 54	iio_evgen->irq_sim_domain = irq_domain_create_sim(NULL,
 55							  IIO_EVENTGEN_NO);
 56	if (IS_ERR(iio_evgen->irq_sim_domain)) {
 57		ret = PTR_ERR(iio_evgen->irq_sim_domain);
 58		kfree(iio_evgen);
 59		return ret;
 60	}
 61
 62	mutex_init(&iio_evgen->lock);
 63
 64	return 0;
 65}
 66
 67/**
 68 * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device
 69 *
 70 * This function will give a free allocated irq to a client device.
 71 * That irq can then be caused to 'fire' by using the associated sysfs file.
 72 */
 73int iio_dummy_evgen_get_irq(void)
 74{
 75	int i, ret = 0;
 76
 77	if (!iio_evgen)
 78		return -ENODEV;
 79
 80	mutex_lock(&iio_evgen->lock);
 81	for (i = 0; i < IIO_EVENTGEN_NO; i++) {
 82		if (!iio_evgen->inuse[i]) {
 83			ret = irq_create_mapping(iio_evgen->irq_sim_domain, i);
 84			iio_evgen->inuse[i] = true;
 85			break;
 86		}
 87	}
 88	mutex_unlock(&iio_evgen->lock);
 89	if (i == IIO_EVENTGEN_NO)
 90		return -ENOMEM;
 91
 92	return ret;
 93}
 94EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);
 95
 96/**
 97 * iio_dummy_evgen_release_irq() - give the irq back.
 98 * @irq: irq being returned to the pool
 99 *
100 * Used by client driver instances to give the irqs back when they disconnect
101 */
102void iio_dummy_evgen_release_irq(int irq)
103{
104	struct irq_data *irqd = irq_get_irq_data(irq);
105
106	mutex_lock(&iio_evgen->lock);
107	iio_evgen->inuse[irqd_to_hwirq(irqd)] = false;
108	irq_dispose_mapping(irq);
109	mutex_unlock(&iio_evgen->lock);
110}
111EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
112
113struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq)
114{
115	struct irq_data *irqd = irq_get_irq_data(irq);
116
117	return &iio_evgen->regs[irqd_to_hwirq(irqd)];
118
119}
120EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
121
122static void iio_dummy_evgen_free(void)
123{
124	irq_domain_remove_sim(iio_evgen->irq_sim_domain);
125	kfree(iio_evgen);
126}
127
128static void iio_evgen_release(struct device *dev)
129{
130	iio_dummy_evgen_free();
131}
132
133static ssize_t iio_evgen_poke(struct device *dev,
134			      struct device_attribute *attr,
135			      const char *buf,
136			      size_t len)
137{
138	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
139	unsigned long event;
140	int ret, irq;
141
142	ret = kstrtoul(buf, 10, &event);
143	if (ret)
144		return ret;
145
146	iio_evgen->regs[this_attr->address].reg_id   = this_attr->address;
147	iio_evgen->regs[this_attr->address].reg_data = event;
148
149	irq = irq_find_mapping(iio_evgen->irq_sim_domain, this_attr->address);
150	ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true);
151	if (ret)
152		return ret;
153
154	return len;
155}
156
157static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
158static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
159static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
160static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
161static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
162static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
163static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
164static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
165static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
166static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
167
168static struct attribute *iio_evgen_attrs[] = {
169	&iio_dev_attr_poke_ev0.dev_attr.attr,
170	&iio_dev_attr_poke_ev1.dev_attr.attr,
171	&iio_dev_attr_poke_ev2.dev_attr.attr,
172	&iio_dev_attr_poke_ev3.dev_attr.attr,
173	&iio_dev_attr_poke_ev4.dev_attr.attr,
174	&iio_dev_attr_poke_ev5.dev_attr.attr,
175	&iio_dev_attr_poke_ev6.dev_attr.attr,
176	&iio_dev_attr_poke_ev7.dev_attr.attr,
177	&iio_dev_attr_poke_ev8.dev_attr.attr,
178	&iio_dev_attr_poke_ev9.dev_attr.attr,
179	NULL,
180};
181
182static const struct attribute_group iio_evgen_group = {
183	.attrs = iio_evgen_attrs,
184};
185
186static const struct attribute_group *iio_evgen_groups[] = {
187	&iio_evgen_group,
188	NULL
189};
190
191static struct device iio_evgen_dev = {
192	.bus = &iio_bus_type,
193	.groups = iio_evgen_groups,
194	.release = &iio_evgen_release,
195};
196
197static __init int iio_dummy_evgen_init(void)
198{
199	int ret = iio_dummy_evgen_create();
200
201	if (ret < 0)
202		return ret;
203	device_initialize(&iio_evgen_dev);
204	dev_set_name(&iio_evgen_dev, "iio_evgen");
205	ret = device_add(&iio_evgen_dev);
206	if (ret)
207		put_device(&iio_evgen_dev);
208	return ret;
209}
210module_init(iio_dummy_evgen_init);
211
212static __exit void iio_dummy_evgen_exit(void)
213{
214	device_unregister(&iio_evgen_dev);
215}
216module_exit(iio_dummy_evgen_exit);
217
218MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
219MODULE_DESCRIPTION("IIO dummy driver");
220MODULE_LICENSE("GPL v2");