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 | |
31 | static irqreturn_t smo8800_interrupt_quick(int irq, void *data) |
32 | { |
33 | struct smo8800_device *smo8800 = data; |
34 | |
35 | atomic_inc(v: &smo8800->counter); |
36 | wake_up_interruptible(&smo8800->misc_wait); |
37 | return IRQ_WAKE_THREAD; |
38 | } |
39 | |
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 | |
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(v: &smo8800->counter, i: 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 | |
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(nr: 0, addr: &smo8800->misc_opened)) |
84 | return -EBUSY; /* already open */ |
85 | |
86 | atomic_set(v: &smo8800->counter, i: 0); |
87 | return 0; |
88 | } |
89 | |
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(nr: 0, addr: &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 | |
106 | static int smo8800_probe(struct platform_device *device) |
107 | { |
108 | int err; |
109 | struct smo8800_device *smo8800; |
110 | |
111 | smo8800 = devm_kzalloc(dev: &device->dev, size: 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(misc: &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(pdev: device, data: 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(irq: smo8800->irq, handler: smo8800_interrupt_quick, |
138 | thread_fn: smo8800_interrupt_thread, |
139 | IRQF_TRIGGER_RISING | IRQF_ONESHOT, |
140 | DRIVER_NAME, dev: 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(misc: &smo8800->miscdev); |
154 | return err; |
155 | } |
156 | |
157 | static void smo8800_remove(struct platform_device *device) |
158 | { |
159 | struct smo8800_device *smo8800 = platform_get_drvdata(pdev: device); |
160 | |
161 | free_irq(smo8800->irq, smo8800); |
162 | misc_deregister(misc: &smo8800->miscdev); |
163 | dev_dbg(&device->dev, "device /dev/freefall unregistered\n" ); |
164 | } |
165 | |
166 | /* NOTE: Keep this list in sync with drivers/i2c/busses/i2c-i801.c */ |
167 | static const struct acpi_device_id smo8800_ids[] = { |
168 | { "SMO8800" , 0 }, |
169 | { "SMO8801" , 0 }, |
170 | { "SMO8810" , 0 }, |
171 | { "SMO8811" , 0 }, |
172 | { "SMO8820" , 0 }, |
173 | { "SMO8821" , 0 }, |
174 | { "SMO8830" , 0 }, |
175 | { "SMO8831" , 0 }, |
176 | { "" , 0 }, |
177 | }; |
178 | MODULE_DEVICE_TABLE(acpi, smo8800_ids); |
179 | |
180 | static struct platform_driver smo8800_driver = { |
181 | .probe = smo8800_probe, |
182 | .remove_new = smo8800_remove, |
183 | .driver = { |
184 | .name = DRIVER_NAME, |
185 | .acpi_match_table = smo8800_ids, |
186 | }, |
187 | }; |
188 | module_platform_driver(smo8800_driver); |
189 | |
190 | MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)" ); |
191 | MODULE_LICENSE("GPL" ); |
192 | MODULE_AUTHOR("Sonal Santan, Pali Rohár" ); |
193 | |