1 /*
2 * dell-smo8800.c - Dell Latitude ACPI SMO8800/SMO8810 freefall sensor driver
3 *
4 * Copyright (C) 2012 Sonal Santan <sonal.santan@gmail.com>
5 * Copyright (C) 2014 Pali Rohár <pali.rohar@gmail.com>
6 *
7 * This is loosely based on lis3lv02d driver.
8 *
9 * This program is free software; you can redistribute it and/or modify
10 * it under the terms of the GNU General Public License as published by
11 * the Free Software Foundation; either version 2 of the License, or
12 * (at your option) any later version.
13 *
14 * This program is distributed in the hope that it will be useful,
15 * but WITHOUT ANY WARRANTY; without even the implied warranty of
16 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
17 * GNU General Public License for more details.
18 */
19
20 #define DRIVER_NAME "smo8800"
21
22 #include <linux/kernel.h>
23 #include <linux/module.h>
24 #include <linux/acpi.h>
25 #include <linux/interrupt.h>
26 #include <linux/miscdevice.h>
27
28 struct smo8800_device {
29 u32 irq; /* acpi device irq */
30 atomic_t counter; /* count after last read */
31 struct miscdevice miscdev; /* for /dev/freefall */
32 unsigned long misc_opened; /* whether the device is open */
33 wait_queue_head_t misc_wait; /* Wait queue for the misc dev */
34 struct device *dev; /* acpi device */
35 };
36
smo8800_interrupt_quick(int irq,void * data)37 static irqreturn_t smo8800_interrupt_quick(int irq, void *data)
38 {
39 struct smo8800_device *smo8800 = data;
40
41 atomic_inc(&smo8800->counter);
42 wake_up_interruptible(&smo8800->misc_wait);
43 return IRQ_WAKE_THREAD;
44 }
45
smo8800_interrupt_thread(int irq,void * data)46 static irqreturn_t smo8800_interrupt_thread(int irq, void *data)
47 {
48 struct smo8800_device *smo8800 = data;
49
50 dev_info(smo8800->dev, "detected free fall\n");
51 return IRQ_HANDLED;
52 }
53
smo8800_get_resource(struct acpi_resource * resource,void * context)54 static acpi_status smo8800_get_resource(struct acpi_resource *resource,
55 void *context)
56 {
57 struct acpi_resource_extended_irq *irq;
58
59 if (resource->type != ACPI_RESOURCE_TYPE_EXTENDED_IRQ)
60 return AE_OK;
61
62 irq = &resource->data.extended_irq;
63 if (!irq || !irq->interrupt_count)
64 return AE_OK;
65
66 *((u32 *)context) = irq->interrupts[0];
67 return AE_CTRL_TERMINATE;
68 }
69
smo8800_get_irq(struct acpi_device * device)70 static u32 smo8800_get_irq(struct acpi_device *device)
71 {
72 u32 irq = 0;
73 acpi_status status;
74
75 status = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
76 smo8800_get_resource, &irq);
77 if (ACPI_FAILURE(status)) {
78 dev_err(&device->dev, "acpi_walk_resources failed\n");
79 return 0;
80 }
81
82 return irq;
83 }
84
smo8800_misc_read(struct file * file,char __user * buf,size_t count,loff_t * pos)85 static ssize_t smo8800_misc_read(struct file *file, char __user *buf,
86 size_t count, loff_t *pos)
87 {
88 struct smo8800_device *smo8800 = container_of(file->private_data,
89 struct smo8800_device, miscdev);
90
91 u32 data = 0;
92 unsigned char byte_data = 0;
93 ssize_t retval = 1;
94
95 if (count < 1)
96 return -EINVAL;
97
98 atomic_set(&smo8800->counter, 0);
99 retval = wait_event_interruptible(smo8800->misc_wait,
100 (data = atomic_xchg(&smo8800->counter, 0)));
101
102 if (retval)
103 return retval;
104
105 byte_data = 1;
106 retval = 1;
107
108 if (data < 255)
109 byte_data = data;
110 else
111 byte_data = 255;
112
113 if (put_user(byte_data, buf))
114 retval = -EFAULT;
115
116 return retval;
117 }
118
smo8800_misc_open(struct inode * inode,struct file * file)119 static int smo8800_misc_open(struct inode *inode, struct file *file)
120 {
121 struct smo8800_device *smo8800 = container_of(file->private_data,
122 struct smo8800_device, miscdev);
123
124 if (test_and_set_bit(0, &smo8800->misc_opened))
125 return -EBUSY; /* already open */
126
127 atomic_set(&smo8800->counter, 0);
128 return 0;
129 }
130
smo8800_misc_release(struct inode * inode,struct file * file)131 static int smo8800_misc_release(struct inode *inode, struct file *file)
132 {
133 struct smo8800_device *smo8800 = container_of(file->private_data,
134 struct smo8800_device, miscdev);
135
136 clear_bit(0, &smo8800->misc_opened); /* release the device */
137 return 0;
138 }
139
140 static const struct file_operations smo8800_misc_fops = {
141 .owner = THIS_MODULE,
142 .read = smo8800_misc_read,
143 .open = smo8800_misc_open,
144 .release = smo8800_misc_release,
145 };
146
smo8800_add(struct acpi_device * device)147 static int smo8800_add(struct acpi_device *device)
148 {
149 int err;
150 struct smo8800_device *smo8800;
151
152 smo8800 = devm_kzalloc(&device->dev, sizeof(*smo8800), GFP_KERNEL);
153 if (!smo8800) {
154 dev_err(&device->dev, "failed to allocate device data\n");
155 return -ENOMEM;
156 }
157
158 smo8800->dev = &device->dev;
159 smo8800->miscdev.minor = MISC_DYNAMIC_MINOR;
160 smo8800->miscdev.name = "freefall";
161 smo8800->miscdev.fops = &smo8800_misc_fops;
162
163 init_waitqueue_head(&smo8800->misc_wait);
164
165 err = misc_register(&smo8800->miscdev);
166 if (err) {
167 dev_err(&device->dev, "failed to register misc dev: %d\n", err);
168 return err;
169 }
170
171 device->driver_data = smo8800;
172
173 smo8800->irq = smo8800_get_irq(device);
174 if (!smo8800->irq) {
175 dev_err(&device->dev, "failed to obtain IRQ\n");
176 err = -EINVAL;
177 goto error;
178 }
179
180 err = request_threaded_irq(smo8800->irq, smo8800_interrupt_quick,
181 smo8800_interrupt_thread,
182 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
183 DRIVER_NAME, smo8800);
184 if (err) {
185 dev_err(&device->dev,
186 "failed to request thread for IRQ %d: %d\n",
187 smo8800->irq, err);
188 goto error;
189 }
190
191 dev_dbg(&device->dev, "device /dev/freefall registered with IRQ %d\n",
192 smo8800->irq);
193 return 0;
194
195 error:
196 misc_deregister(&smo8800->miscdev);
197 return err;
198 }
199
smo8800_remove(struct acpi_device * device)200 static int smo8800_remove(struct acpi_device *device)
201 {
202 struct smo8800_device *smo8800 = device->driver_data;
203
204 free_irq(smo8800->irq, smo8800);
205 misc_deregister(&smo8800->miscdev);
206 dev_dbg(&device->dev, "device /dev/freefall unregistered\n");
207 return 0;
208 }
209
210 static const struct acpi_device_id smo8800_ids[] = {
211 { "SMO8800", 0 },
212 { "SMO8810", 0 },
213 { "", 0 },
214 };
215
216 MODULE_DEVICE_TABLE(acpi, smo8800_ids);
217
218 static struct acpi_driver smo8800_driver = {
219 .name = DRIVER_NAME,
220 .class = "Latitude",
221 .ids = smo8800_ids,
222 .ops = {
223 .add = smo8800_add,
224 .remove = smo8800_remove,
225 },
226 .owner = THIS_MODULE,
227 };
228
229 module_acpi_driver(smo8800_driver);
230
231 MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO8800/SMO8810)");
232 MODULE_LICENSE("GPL");
233 MODULE_AUTHOR("Sonal Santan, Pali Rohár");
234