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