1 /*
2 * dell-smo8800.c - Dell Latitude ACPI SMO88XX 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 #include <linux/uaccess.h>
28
29 struct smo8800_device {
30 u32 irq; /* acpi device irq */
31 atomic_t counter; /* count after last read */
32 struct miscdevice miscdev; /* for /dev/freefall */
33 unsigned long misc_opened; /* whether the device is open */
34 wait_queue_head_t misc_wait; /* Wait queue for the misc dev */
35 struct device *dev; /* acpi device */
36 };
37
smo8800_interrupt_quick(int irq,void * data)38 static irqreturn_t smo8800_interrupt_quick(int irq, void *data)
39 {
40 struct smo8800_device *smo8800 = data;
41
42 atomic_inc(&smo8800->counter);
43 wake_up_interruptible(&smo8800->misc_wait);
44 return IRQ_WAKE_THREAD;
45 }
46
smo8800_interrupt_thread(int irq,void * data)47 static irqreturn_t smo8800_interrupt_thread(int irq, void *data)
48 {
49 struct smo8800_device *smo8800 = data;
50
51 dev_info(smo8800->dev, "detected free fall\n");
52 return IRQ_HANDLED;
53 }
54
smo8800_get_resource(struct acpi_resource * resource,void * context)55 static acpi_status smo8800_get_resource(struct acpi_resource *resource,
56 void *context)
57 {
58 struct acpi_resource_extended_irq *irq;
59
60 if (resource->type != ACPI_RESOURCE_TYPE_EXTENDED_IRQ)
61 return AE_OK;
62
63 irq = &resource->data.extended_irq;
64 if (!irq || !irq->interrupt_count)
65 return AE_OK;
66
67 *((u32 *)context) = irq->interrupts[0];
68 return AE_CTRL_TERMINATE;
69 }
70
smo8800_get_irq(struct acpi_device * device)71 static u32 smo8800_get_irq(struct acpi_device *device)
72 {
73 u32 irq = 0;
74 acpi_status status;
75
76 status = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
77 smo8800_get_resource, &irq);
78 if (ACPI_FAILURE(status)) {
79 dev_err(&device->dev, "acpi_walk_resources failed\n");
80 return 0;
81 }
82
83 return irq;
84 }
85
smo8800_misc_read(struct file * file,char __user * buf,size_t count,loff_t * pos)86 static ssize_t smo8800_misc_read(struct file *file, char __user *buf,
87 size_t count, loff_t *pos)
88 {
89 struct smo8800_device *smo8800 = container_of(file->private_data,
90 struct smo8800_device, miscdev);
91
92 u32 data = 0;
93 unsigned char byte_data;
94 ssize_t retval = 1;
95
96 if (count < 1)
97 return -EINVAL;
98
99 atomic_set(&smo8800->counter, 0);
100 retval = wait_event_interruptible(smo8800->misc_wait,
101 (data = atomic_xchg(&smo8800->counter, 0)));
102
103 if (retval)
104 return retval;
105
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 { "SMO8801", 0 },
213 { "SMO8810", 0 },
214 { "SMO8811", 0 },
215 { "SMO8820", 0 },
216 { "SMO8821", 0 },
217 { "SMO8830", 0 },
218 { "SMO8831", 0 },
219 { "", 0 },
220 };
221
222 MODULE_DEVICE_TABLE(acpi, smo8800_ids);
223
224 static struct acpi_driver smo8800_driver = {
225 .name = DRIVER_NAME,
226 .class = "Latitude",
227 .ids = smo8800_ids,
228 .ops = {
229 .add = smo8800_add,
230 .remove = smo8800_remove,
231 },
232 .owner = THIS_MODULE,
233 };
234
235 module_acpi_driver(smo8800_driver);
236
237 MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)");
238 MODULE_LICENSE("GPL");
239 MODULE_AUTHOR("Sonal Santan, Pali Rohár");
240
