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: interrupt simulator
35 * @base: base of irq range
36 * @irq_sim_domain: irq simulator domain
37 */
38struct iio_dummy_eventgen {
39	struct iio_dummy_regs regs[IIO_EVENTGEN_NO];
40	struct mutex lock;
41	bool inuse[IIO_EVENTGEN_NO];
42	struct irq_domain *irq_sim_domain;
43};
44
45/* We can only ever have one instance of this 'device' */
46static struct iio_dummy_eventgen *iio_evgen;
47
48static int iio_dummy_evgen_create(void)
49{
50	int ret;
51
52	iio_evgen = kzalloc(sizeof(*iio_evgen), GFP_KERNEL);
53	if (!iio_evgen)
54		return -ENOMEM;
55
56	iio_evgen->irq_sim_domain = irq_domain_create_sim(NULL,
57							  IIO_EVENTGEN_NO);
58	if (IS_ERR(iio_evgen->irq_sim_domain)) {
59		ret = PTR_ERR(iio_evgen->irq_sim_domain);
60		kfree(iio_evgen);
61		return ret;
62	}
63
64	mutex_init(&iio_evgen->lock);
65
66	return 0;
67}
68
69/**
70 * iio_dummy_evgen_get_irq() - get an evgen provided irq for a device
71 *
72 * This function will give a free allocated irq to a client device.
73 * That irq can then be caused to 'fire' by using the associated sysfs file.
74 */
75int iio_dummy_evgen_get_irq(void)
76{
77	int i, ret = 0;
78
79	if (!iio_evgen)
80		return -ENODEV;
81
82	mutex_lock(&iio_evgen->lock);
83	for (i = 0; i < IIO_EVENTGEN_NO; i++) {
84		if (!iio_evgen->inuse[i]) {
85			ret = irq_create_mapping(iio_evgen->irq_sim_domain, i);
86			iio_evgen->inuse[i] = true;
87			break;
88		}
89	}
90	mutex_unlock(&iio_evgen->lock);
91	if (i == IIO_EVENTGEN_NO)
92		return -ENOMEM;
93
94	return ret;
95}
96EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_irq);
97
98/**
99 * iio_dummy_evgen_release_irq() - give the irq back.
100 * @irq: irq being returned to the pool
101 *
102 * Used by client driver instances to give the irqs back when they disconnect
103 */
104void iio_dummy_evgen_release_irq(int irq)
105{
106	struct irq_data *irqd = irq_get_irq_data(irq);
107
108	mutex_lock(&iio_evgen->lock);
109	iio_evgen->inuse[irqd_to_hwirq(irqd)] = false;
110	irq_dispose_mapping(irq);
111	mutex_unlock(&iio_evgen->lock);
112}
113EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
114
115struct iio_dummy_regs *iio_dummy_evgen_get_regs(int irq)
116{
117	struct irq_data *irqd = irq_get_irq_data(irq);
118
119	return &iio_evgen->regs[irqd_to_hwirq(irqd)];
120
121}
122EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
123
124static void iio_dummy_evgen_free(void)
125{
126	irq_domain_remove_sim(iio_evgen->irq_sim_domain);
127	kfree(iio_evgen);
128}
129
130static void iio_evgen_release(struct device *dev)
131{
132	iio_dummy_evgen_free();
133}
134
135static ssize_t iio_evgen_poke(struct device *dev,
136			      struct device_attribute *attr,
137			      const char *buf,
138			      size_t len)
139{
140	struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
141	unsigned long event;
142	int ret, irq;
143
144	ret = kstrtoul(buf, 10, &event);
145	if (ret)
146		return ret;
147
148	iio_evgen->regs[this_attr->address].reg_id   = this_attr->address;
149	iio_evgen->regs[this_attr->address].reg_data = event;
150
151	irq = irq_find_mapping(iio_evgen->irq_sim_domain, this_attr->address);
152	ret = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, true);
153	if (ret)
154		return ret;
155
156	return len;
157}
158
159static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
160static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
161static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
162static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
163static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
164static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
165static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
166static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
167static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
168static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
169
170static struct attribute *iio_evgen_attrs[] = {
171	&iio_dev_attr_poke_ev0.dev_attr.attr,
172	&iio_dev_attr_poke_ev1.dev_attr.attr,
173	&iio_dev_attr_poke_ev2.dev_attr.attr,
174	&iio_dev_attr_poke_ev3.dev_attr.attr,
175	&iio_dev_attr_poke_ev4.dev_attr.attr,
176	&iio_dev_attr_poke_ev5.dev_attr.attr,
177	&iio_dev_attr_poke_ev6.dev_attr.attr,
178	&iio_dev_attr_poke_ev7.dev_attr.attr,
179	&iio_dev_attr_poke_ev8.dev_attr.attr,
180	&iio_dev_attr_poke_ev9.dev_attr.attr,
181	NULL,
182};
183
184static const struct attribute_group iio_evgen_group = {
185	.attrs = iio_evgen_attrs,
186};
187
188static const struct attribute_group *iio_evgen_groups[] = {
189	&iio_evgen_group,
190	NULL
191};
192
193static struct device iio_evgen_dev = {
194	.bus = &iio_bus_type,
195	.groups = iio_evgen_groups,
196	.release = &iio_evgen_release,
197};
198
199static __init int iio_dummy_evgen_init(void)
200{
201	int ret = iio_dummy_evgen_create();
202
203	if (ret < 0)
204		return ret;
205	device_initialize(&iio_evgen_dev);
206	dev_set_name(&iio_evgen_dev, "iio_evgen");
207	ret = device_add(&iio_evgen_dev);
208	if (ret)
209		put_device(&iio_evgen_dev);
210	return ret;
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