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