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
 22struct 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
 31static 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
 40static 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
 48static 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	if (data < 255)
 71		byte_data = data;
 72	else
 73		byte_data = 255;
 74
 75	if (put_user(byte_data, buf))
 76		retval = -EFAULT;
 77
 78	return retval;
 79}
 80
 81static int smo8800_misc_open(struct inode *inode, struct file *file)
 82{
 83	struct smo8800_device *smo8800 = container_of(file->private_data,
 84					 struct smo8800_device, miscdev);
 85
 86	if (test_and_set_bit(0, &smo8800->misc_opened))
 87		return -EBUSY; /* already open */
 88
 89	atomic_set(&smo8800->counter, 0);
 90	return 0;
 91}
 92
 93static int smo8800_misc_release(struct inode *inode, struct file *file)
 94{
 95	struct smo8800_device *smo8800 = container_of(file->private_data,
 96					 struct smo8800_device, miscdev);
 97
 98	clear_bit(0, &smo8800->misc_opened); /* release the device */
 99	return 0;
100}
101
102static const struct file_operations smo8800_misc_fops = {
103	.owner = THIS_MODULE,
104	.read = smo8800_misc_read,
105	.open = smo8800_misc_open,
106	.release = smo8800_misc_release,
107};
108
109static int smo8800_probe(struct platform_device *device)
110{
111	int err;
112	struct smo8800_device *smo8800;
113
114	smo8800 = devm_kzalloc(&device->dev, sizeof(*smo8800), GFP_KERNEL);
115	if (!smo8800) {
116		dev_err(&device->dev, "failed to allocate device data\n");
117		return -ENOMEM;
118	}
119
120	smo8800->dev = &device->dev;
121	smo8800->miscdev.minor = MISC_DYNAMIC_MINOR;
122	smo8800->miscdev.name = "freefall";
123	smo8800->miscdev.fops = &smo8800_misc_fops;
124
125	init_waitqueue_head(&smo8800->misc_wait);
126
127	err = misc_register(&smo8800->miscdev);
128	if (err) {
129		dev_err(&device->dev, "failed to register misc dev: %d\n", err);
130		return err;
131	}
132
133	platform_set_drvdata(device, smo8800);
134
135	err = platform_get_irq(device, 0);
136	if (err < 0)
137		goto error;
138	smo8800->irq = err;
139
140	err = request_threaded_irq(smo8800->irq, smo8800_interrupt_quick,
141				   smo8800_interrupt_thread,
142				   IRQF_TRIGGER_RISING | IRQF_ONESHOT,
143				   DRIVER_NAME, smo8800);
144	if (err) {
145		dev_err(&device->dev,
146			"failed to request thread for IRQ %d: %d\n",
147			smo8800->irq, err);
148		goto error;
149	}
150
151	dev_dbg(&device->dev, "device /dev/freefall registered with IRQ %d\n",
152		 smo8800->irq);
153	return 0;
154
155error:
156	misc_deregister(&smo8800->miscdev);
157	return err;
158}
159
160static int smo8800_remove(struct platform_device *device)
161{
162	struct smo8800_device *smo8800 = platform_get_drvdata(device);
163
164	free_irq(smo8800->irq, smo8800);
165	misc_deregister(&smo8800->miscdev);
166	dev_dbg(&device->dev, "device /dev/freefall unregistered\n");
167	return 0;
168}
169
170/* NOTE: Keep this list in sync with drivers/i2c/busses/i2c-i801.c */
171static const struct acpi_device_id smo8800_ids[] = {
172	{ "SMO8800", 0 },
173	{ "SMO8801", 0 },
174	{ "SMO8810", 0 },
175	{ "SMO8811", 0 },
176	{ "SMO8820", 0 },
177	{ "SMO8821", 0 },
178	{ "SMO8830", 0 },
179	{ "SMO8831", 0 },
180	{ "", 0 },
181};
182MODULE_DEVICE_TABLE(acpi, smo8800_ids);
183
184static struct platform_driver smo8800_driver = {
185	.probe = smo8800_probe,
186	.remove = smo8800_remove,
187	.driver = {
188		.name = DRIVER_NAME,
189		.acpi_match_table = smo8800_ids,
190	},
191};
192module_platform_driver(smo8800_driver);
193
194MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)");
195MODULE_LICENSE("GPL");
196MODULE_AUTHOR("Sonal Santan, Pali Rohár");