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@kernel.org>
7 *
8 * This is loosely based on lis3lv02d driver.
9 */
10
11 #define DRIVER_NAME "smo8800"
12
13 #include <linux/fs.h>
14 #include <linux/interrupt.h>
15 #include <linux/kernel.h>
16 #include <linux/miscdevice.h>
17 #include <linux/mod_devicetable.h>
18 #include <linux/module.h>
19 #include <linux/platform_device.h>
20 #include <linux/uaccess.h>
21
22 struct smo8800_device {
23 u32 irq; /* acpi device irq */
24 atomic_t counter; /* count after last read */
25 struct miscdevice miscdev; /* for /dev/freefall */
26 unsigned long misc_opened; /* whether the device is open */
27 wait_queue_head_t misc_wait; /* Wait queue for the misc dev */
28 struct device *dev; /* acpi device */
29 };
30
smo8800_interrupt_quick(int irq,void * data)31 static irqreturn_t smo8800_interrupt_quick(int irq, void *data)
32 {
33 struct smo8800_device *smo8800 = data;
34
35 atomic_inc(&smo8800->counter);
36 wake_up_interruptible(&smo8800->misc_wait);
37 return IRQ_WAKE_THREAD;
38 }
39
smo8800_interrupt_thread(int irq,void * data)40 static irqreturn_t smo8800_interrupt_thread(int irq, void *data)
41 {
42 struct smo8800_device *smo8800 = data;
43
44 dev_info(smo8800->dev, "detected free fall\n");
45 return IRQ_HANDLED;
46 }
47
smo8800_misc_read(struct file * file,char __user * buf,size_t count,loff_t * pos)48 static ssize_t smo8800_misc_read(struct file *file, char __user *buf,
49 size_t count, loff_t *pos)
50 {
51 struct smo8800_device *smo8800 = container_of(file->private_data,
52 struct smo8800_device, miscdev);
53
54 u32 data = 0;
55 unsigned char byte_data;
56 ssize_t retval = 1;
57
58 if (count < 1)
59 return -EINVAL;
60
61 atomic_set(&smo8800->counter, 0);
62 retval = wait_event_interruptible(smo8800->misc_wait,
63 (data = atomic_xchg(&smo8800->counter, 0)));
64
65 if (retval)
66 return retval;
67
68 retval = 1;
69
70 byte_data = min_t(u32, data, 255);
71
72 if (put_user(byte_data, buf))
73 retval = -EFAULT;
74
75 return retval;
76 }
77
smo8800_misc_open(struct inode * inode,struct file * file)78 static int smo8800_misc_open(struct inode *inode, struct file *file)
79 {
80 struct smo8800_device *smo8800 = container_of(file->private_data,
81 struct smo8800_device, miscdev);
82
83 if (test_and_set_bit(0, &smo8800->misc_opened))
84 return -EBUSY; /* already open */
85
86 atomic_set(&smo8800->counter, 0);
87 return 0;
88 }
89
smo8800_misc_release(struct inode * inode,struct file * file)90 static int smo8800_misc_release(struct inode *inode, struct file *file)
91 {
92 struct smo8800_device *smo8800 = container_of(file->private_data,
93 struct smo8800_device, miscdev);
94
95 clear_bit(0, &smo8800->misc_opened); /* release the device */
96 return 0;
97 }
98
99 static const struct file_operations smo8800_misc_fops = {
100 .owner = THIS_MODULE,
101 .read = smo8800_misc_read,
102 .open = smo8800_misc_open,
103 .release = smo8800_misc_release,
104 };
105
smo8800_probe(struct platform_device * device)106 static int smo8800_probe(struct platform_device *device)
107 {
108 int err;
109 struct smo8800_device *smo8800;
110
111 smo8800 = devm_kzalloc(&device->dev, sizeof(*smo8800), GFP_KERNEL);
112 if (!smo8800) {
113 dev_err(&device->dev, "failed to allocate device data\n");
114 return -ENOMEM;
115 }
116
117 smo8800->dev = &device->dev;
118 smo8800->miscdev.minor = MISC_DYNAMIC_MINOR;
119 smo8800->miscdev.name = "freefall";
120 smo8800->miscdev.fops = &smo8800_misc_fops;
121
122 init_waitqueue_head(&smo8800->misc_wait);
123
124 err = misc_register(&smo8800->miscdev);
125 if (err) {
126 dev_err(&device->dev, "failed to register misc dev: %d\n", err);
127 return err;
128 }
129
130 platform_set_drvdata(device, smo8800);
131
132 err = platform_get_irq(device, 0);
133 if (err < 0)
134 goto error;
135 smo8800->irq = err;
136
137 err = request_threaded_irq(smo8800->irq, smo8800_interrupt_quick,
138 smo8800_interrupt_thread,
139 IRQF_TRIGGER_RISING | IRQF_ONESHOT,
140 DRIVER_NAME, smo8800);
141 if (err) {
142 dev_err(&device->dev,
143 "failed to request thread for IRQ %d: %d\n",
144 smo8800->irq, err);
145 goto error;
146 }
147
148 dev_dbg(&device->dev, "device /dev/freefall registered with IRQ %d\n",
149 smo8800->irq);
150 return 0;
151
152 error:
153 misc_deregister(&smo8800->miscdev);
154 return err;
155 }
156
smo8800_remove(struct platform_device * device)157 static int smo8800_remove(struct platform_device *device)
158 {
159 struct smo8800_device *smo8800 = platform_get_drvdata(device);
160
161 free_irq(smo8800->irq, smo8800);
162 misc_deregister(&smo8800->miscdev);
163 dev_dbg(&device->dev, "device /dev/freefall unregistered\n");
164 return 0;
165 }
166
167 /* NOTE: Keep this list in sync with drivers/i2c/busses/i2c-i801.c */
168 static const struct acpi_device_id smo8800_ids[] = {
169 { "SMO8800", 0 },
170 { "SMO8801", 0 },
171 { "SMO8810", 0 },
172 { "SMO8811", 0 },
173 { "SMO8820", 0 },
174 { "SMO8821", 0 },
175 { "SMO8830", 0 },
176 { "SMO8831", 0 },
177 { "", 0 },
178 };
179 MODULE_DEVICE_TABLE(acpi, smo8800_ids);
180
181 static struct platform_driver smo8800_driver = {
182 .probe = smo8800_probe,
183 .remove = smo8800_remove,
184 .driver = {
185 .name = DRIVER_NAME,
186 .acpi_match_table = smo8800_ids,
187 },
188 };
189 module_platform_driver(smo8800_driver);
190
191 MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)");
192 MODULE_LICENSE("GPL");
193 MODULE_AUTHOR("Sonal Santan, Pali Rohár");
194