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
 20struct 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
 29static 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
 38static 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
 46static 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
 62static 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
 77static 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
110static 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
122static 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
131static 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
138static 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
186error:
187	misc_deregister(&smo8800->miscdev);
188	return err;
189}
190
191static 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 */
202static 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
214MODULE_DEVICE_TABLE(acpi, smo8800_ids);
215
216static 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
227module_acpi_driver(smo8800_driver);
228
229MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)");
230MODULE_LICENSE("GPL");
231MODULE_AUTHOR("Sonal Santan, Pali Rohár");