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 */
38 struct 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' */
46 static struct iio_dummy_eventgen *iio_evgen;
47
iio_dummy_evgen_create(void)48 static 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 */
iio_dummy_evgen_get_irq(void)75 int 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 }
96 EXPORT_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 */
iio_dummy_evgen_release_irq(int irq)104 void 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 }
113 EXPORT_SYMBOL_GPL(iio_dummy_evgen_release_irq);
114
iio_dummy_evgen_get_regs(int irq)115 struct 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 }
122 EXPORT_SYMBOL_GPL(iio_dummy_evgen_get_regs);
123
iio_dummy_evgen_free(void)124 static void iio_dummy_evgen_free(void)
125 {
126 irq_domain_remove_sim(iio_evgen->irq_sim_domain);
127 kfree(iio_evgen);
128 }
129
iio_evgen_release(struct device * dev)130 static void iio_evgen_release(struct device *dev)
131 {
132 iio_dummy_evgen_free();
133 }
134
iio_evgen_poke(struct device * dev,struct device_attribute * attr,const char * buf,size_t len)135 static 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
159 static IIO_DEVICE_ATTR(poke_ev0, S_IWUSR, NULL, &iio_evgen_poke, 0);
160 static IIO_DEVICE_ATTR(poke_ev1, S_IWUSR, NULL, &iio_evgen_poke, 1);
161 static IIO_DEVICE_ATTR(poke_ev2, S_IWUSR, NULL, &iio_evgen_poke, 2);
162 static IIO_DEVICE_ATTR(poke_ev3, S_IWUSR, NULL, &iio_evgen_poke, 3);
163 static IIO_DEVICE_ATTR(poke_ev4, S_IWUSR, NULL, &iio_evgen_poke, 4);
164 static IIO_DEVICE_ATTR(poke_ev5, S_IWUSR, NULL, &iio_evgen_poke, 5);
165 static IIO_DEVICE_ATTR(poke_ev6, S_IWUSR, NULL, &iio_evgen_poke, 6);
166 static IIO_DEVICE_ATTR(poke_ev7, S_IWUSR, NULL, &iio_evgen_poke, 7);
167 static IIO_DEVICE_ATTR(poke_ev8, S_IWUSR, NULL, &iio_evgen_poke, 8);
168 static IIO_DEVICE_ATTR(poke_ev9, S_IWUSR, NULL, &iio_evgen_poke, 9);
169
170 static 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
184 static const struct attribute_group iio_evgen_group = {
185 .attrs = iio_evgen_attrs,
186 };
187
188 static const struct attribute_group *iio_evgen_groups[] = {
189 &iio_evgen_group,
190 NULL
191 };
192
193 static struct device iio_evgen_dev = {
194 .bus = &iio_bus_type,
195 .groups = iio_evgen_groups,
196 .release = &iio_evgen_release,
197 };
198
iio_dummy_evgen_init(void)199 static __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 }
212 module_init(iio_dummy_evgen_init);
213
iio_dummy_evgen_exit(void)214 static __exit void iio_dummy_evgen_exit(void)
215 {
216 device_unregister(&iio_evgen_dev);
217 }
218 module_exit(iio_dummy_evgen_exit);
219
220 MODULE_AUTHOR("Jonathan Cameron <jic23@kernel.org>");
221 MODULE_DESCRIPTION("IIO dummy driver");
222 MODULE_LICENSE("GPL v2");
223