1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * dell-smo8800.c - Dell Latitude ACPI SMO88XX freefall sensor driver
4 *
5 * Copyright (C) 2012 Sonal Santan <sonal.santan@gmail.com>
6 * Copyright (C) 2014 Pali Rohár <pali.rohar@gmail.com>
7 *
8 * This is loosely based on lis3lv02d driver.
9 */
10
11 #define DRIVER_NAME "smo8800"
12
13 #include <linux/kernel.h>
14 #include <linux/module.h>
15 #include <linux/acpi.h>
16 #include <linux/interrupt.h>
17 #include <linux/miscdevice.h>
18 #include <linux/uaccess.h>
19
20 struct smo8800_device {
21 u32 irq; /* acpi device irq */
22 atomic_t counter; /* count after last read */
23 struct miscdevice miscdev; /* for /dev/freefall */
24 unsigned long misc_opened; /* whether the device is open */
25 wait_queue_head_t misc_wait; /* Wait queue for the misc dev */
26 struct device *dev; /* acpi device */
27 };
28
smo8800_interrupt_quick(int irq,void * data)29 static irqreturn_t smo8800_interrupt_quick(int irq, void *data)
30 {
31 struct smo8800_device *smo8800 = data;
32
33 atomic_inc(&smo8800->counter);
34 wake_up_interruptible(&smo8800->misc_wait);
35 return IRQ_WAKE_THREAD;
36 }
37
smo8800_interrupt_thread(int irq,void * data)38 static irqreturn_t smo8800_interrupt_thread(int irq, void *data)
39 {
40 struct smo8800_device *smo8800 = data;
41
42 dev_info(smo8800->dev, "detected free fall\n");
43 return IRQ_HANDLED;
44 }
45
smo8800_get_resource(struct acpi_resource * resource,void * context)46 static acpi_status smo8800_get_resource(struct acpi_resource *resource,
47 void *context)
48 {
49 struct acpi_resource_extended_irq *irq;
50
51 if (resource->type != ACPI_RESOURCE_TYPE_EXTENDED_IRQ)
52 return AE_OK;
53
54 irq = &resource->data.extended_irq;
55 if (!irq || !irq->interrupt_count)
56 return AE_OK;
57
58 *((u32 *)context) = irq->interrupts[0];
59 return AE_CTRL_TERMINATE;
60 }
61
smo8800_get_irq(struct acpi_device * device)62 static u32 smo8800_get_irq(struct acpi_device *device)
63 {
64 u32 irq = 0;
65 acpi_status status;
66
67 status = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
68 smo8800_get_resource, &irq);
69 if (ACPI_FAILURE(status)) {
70 dev_err(&device->dev, "acpi_walk_resources failed\n");
71 return 0;
72 }
73
74 return irq;
75 }
76
smo8800_misc_read(struct file * file,char __user * buf,size_t count,loff_t * pos)77 static ssize_t smo8800_misc_read(struct file *file, char __user *buf,
78 size_t count, loff_t *pos)
79 {
80 struct smo8800_device *smo8800 = container_of(file->private_data,
81 struct smo8800_device, miscdev);
82
83 u32 data = 0;
84 unsigned char byte_data;
85 ssize_t retval = 1;
86
87 if (count < 1)
88 return -EINVAL;
89
90 atomic_set(&smo8800->counter, 0);
91 retval = wait_event_interruptible(smo8800->misc_wait,
92 (data = atomic_xchg(&smo8800->counter, 0)));
93
94 if (retval)
95 return retval;
96
97 retval = 1;
98
99 if (data < 255)
100 byte_data = data;
101 else
102 byte_data = 255;
103
104 if (put_user(byte_data, buf))
105 retval = -EFAULT;
106
107 return retval;
108 }
109
smo8800_misc_open(struct inode * inode,struct file * file)110 static int smo8800_misc_open(struct inode *inode, struct file *file)
111 {
112 struct smo8800_device *smo8800 = container_of(file->private_data,
113 struct smo8800_device, miscdev);
114
115 if (test_and_set_bit(0, &smo8800->misc_opened))
116 return -EBUSY; /* already open */
117
118 atomic_set(&smo8800->counter, 0);
119 return 0;
120 }
121
smo8800_misc_release(struct inode * inode,struct file * file)122 static int smo8800_misc_release(struct inode *inode, struct file *file)
123 {
124 struct smo8800_device *smo8800 = container_of(file->private_data,
125 struct smo8800_device, miscdev);
126
127 clear_bit(0, &smo8800->misc_opened); /* release the device */
128 return 0;
129 }
130
131 static const struct file_operations smo8800_misc_fops = {
132 .owner = THIS_MODULE,
133 .read = smo8800_misc_read,
134 .open = smo8800_misc_open,
135 .release = smo8800_misc_release,
136 };
137
smo8800_add(struct acpi_device * device)138 static int smo8800_add(struct acpi_device *device)
139 {
140 int err;
141 struct smo8800_device *smo8800;
142
143 smo8800 = devm_kzalloc(&device->dev, sizeof(*smo8800), GFP_KERNEL);
144 if (!smo8800) {
145 dev_err(&device->dev, "failed to allocate device data\n");
146 return -ENOMEM;
147 }
148
149 smo8800->dev = &device->dev;
150 smo8800->miscdev.minor = MISC_DYNAMIC_MINOR;
151 smo8800->miscdev.name = "freefall";
152 smo8800->miscdev.fops = &smo8800_misc_fops;
153
154 init_waitqueue_head(&smo8800->misc_wait);
155
156 err = misc_register(&smo8800->miscdev);
157 if (err) {
158 dev_err(&device->dev, "failed to register misc dev: %d\n", err);
159 return err;
160 }
161
162 device->driver_data = smo8800;
163
164 smo8800->irq = smo8800_get_irq(device);
165 if (!smo8800->irq) {
166 dev_err(&device->dev, "failed to obtain IRQ\n");
167 err = -EINVAL;
168 goto error;
169 }
170
171 err = request_threaded_irq(smo8800->irq, smo8800_interrupt_quick,
172 smo8800_interrupt_thread,
173 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
174 DRIVER_NAME, smo8800);
175 if (err) {
176 dev_err(&device->dev,
177 "failed to request thread for IRQ %d: %d\n",
178 smo8800->irq, err);
179 goto error;
180 }
181
182 dev_dbg(&device->dev, "device /dev/freefall registered with IRQ %d\n",
183 smo8800->irq);
184 return 0;
185
186 error:
187 misc_deregister(&smo8800->miscdev);
188 return err;
189 }
190
smo8800_remove(struct acpi_device * device)191 static int smo8800_remove(struct acpi_device *device)
192 {
193 struct smo8800_device *smo8800 = device->driver_data;
194
195 free_irq(smo8800->irq, smo8800);
196 misc_deregister(&smo8800->miscdev);
197 dev_dbg(&device->dev, "device /dev/freefall unregistered\n");
198 return 0;
199 }
200
201 /* NOTE: Keep this list in sync with drivers/i2c/busses/i2c-i801.c */
202 static const struct acpi_device_id smo8800_ids[] = {
203 { "SMO8800", 0 },
204 { "SMO8801", 0 },
205 { "SMO8810", 0 },
206 { "SMO8811", 0 },
207 { "SMO8820", 0 },
208 { "SMO8821", 0 },
209 { "SMO8830", 0 },
210 { "SMO8831", 0 },
211 { "", 0 },
212 };
213
214 MODULE_DEVICE_TABLE(acpi, smo8800_ids);
215
216 static struct acpi_driver smo8800_driver = {
217 .name = DRIVER_NAME,
218 .class = "Latitude",
219 .ids = smo8800_ids,
220 .ops = {
221 .add = smo8800_add,
222 .remove = smo8800_remove,
223 },
224 .owner = THIS_MODULE,
225 };
226
227 module_acpi_driver(smo8800_driver);
228
229 MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)");
230 MODULE_LICENSE("GPL");
231 MODULE_AUTHOR("Sonal Santan, Pali Rohár");
232
