1/*
  2 *  dell-smo8800.c - Dell Latitude ACPI SMO88XX freefall sensor driver
  3 *
  4 *  Copyright (C) 2012 Sonal Santan <sonal.santan@gmail.com>
  5 *  Copyright (C) 2014 Pali Rohár <pali.rohar@gmail.com>
  6 *
  7 *  This is loosely based on lis3lv02d driver.
  8 *
  9 *  This program is free software; you can redistribute it and/or modify
 10 *  it under the terms of the GNU General Public License as published by
 11 *  the Free Software Foundation; either version 2 of the License, or
 12 *  (at your option) any later version.
 13 *
 14 *  This program is distributed in the hope that it will be useful,
 15 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 16 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 17 *  GNU General Public License for more details.
 18 */
 19
 20#define DRIVER_NAME "smo8800"
 21
 22#include <linux/kernel.h>
 23#include <linux/module.h>
 24#include <linux/acpi.h>
 25#include <linux/interrupt.h>
 26#include <linux/miscdevice.h>
 27#include <linux/uaccess.h>
 28
 29struct smo8800_device {
 30	u32 irq;                     /* acpi device irq */
 31	atomic_t counter;            /* count after last read */
 32	struct miscdevice miscdev;   /* for /dev/freefall */
 33	unsigned long misc_opened;   /* whether the device is open */
 34	wait_queue_head_t misc_wait; /* Wait queue for the misc dev */
 35	struct device *dev;          /* acpi device */
 36};
 37
 38static irqreturn_t smo8800_interrupt_quick(int irq, void *data)
 39{
 40	struct smo8800_device *smo8800 = data;
 41
 42	atomic_inc(&smo8800->counter);
 43	wake_up_interruptible(&smo8800->misc_wait);
 44	return IRQ_WAKE_THREAD;
 45}
 46
 47static irqreturn_t smo8800_interrupt_thread(int irq, void *data)
 48{
 49	struct smo8800_device *smo8800 = data;
 50
 51	dev_info(smo8800->dev, "detected free fall\n");
 52	return IRQ_HANDLED;
 53}
 54
 55static acpi_status smo8800_get_resource(struct acpi_resource *resource,
 56					void *context)
 57{
 58	struct acpi_resource_extended_irq *irq;
 59
 60	if (resource->type != ACPI_RESOURCE_TYPE_EXTENDED_IRQ)
 61		return AE_OK;
 62
 63	irq = &resource->data.extended_irq;
 64	if (!irq || !irq->interrupt_count)
 65		return AE_OK;
 66
 67	*((u32 *)context) = irq->interrupts[0];
 68	return AE_CTRL_TERMINATE;
 69}
 70
 71static u32 smo8800_get_irq(struct acpi_device *device)
 72{
 73	u32 irq = 0;
 74	acpi_status status;
 75
 76	status = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
 77				     smo8800_get_resource, &irq);
 78	if (ACPI_FAILURE(status)) {
 79		dev_err(&device->dev, "acpi_walk_resources failed\n");
 80		return 0;
 81	}
 82
 83	return irq;
 84}
 85
 86static ssize_t smo8800_misc_read(struct file *file, char __user *buf,
 87				 size_t count, loff_t *pos)
 88{
 89	struct smo8800_device *smo8800 = container_of(file->private_data,
 90					 struct smo8800_device, miscdev);
 91
 92	u32 data = 0;
 93	unsigned char byte_data;
 94	ssize_t retval = 1;
 95
 96	if (count < 1)
 97		return -EINVAL;
 98
 99	atomic_set(&smo8800->counter, 0);
100	retval = wait_event_interruptible(smo8800->misc_wait,
101				(data = atomic_xchg(&smo8800->counter, 0)));
102
103	if (retval)
104		return retval;
105
106	retval = 1;
107
108	if (data < 255)
109		byte_data = data;
110	else
111		byte_data = 255;
112
113	if (put_user(byte_data, buf))
114		retval = -EFAULT;
115
116	return retval;
117}
118
119static int smo8800_misc_open(struct inode *inode, struct file *file)
120{
121	struct smo8800_device *smo8800 = container_of(file->private_data,
122					 struct smo8800_device, miscdev);
123
124	if (test_and_set_bit(0, &smo8800->misc_opened))
125		return -EBUSY; /* already open */
126
127	atomic_set(&smo8800->counter, 0);
128	return 0;
129}
130
131static int smo8800_misc_release(struct inode *inode, struct file *file)
132{
133	struct smo8800_device *smo8800 = container_of(file->private_data,
134					 struct smo8800_device, miscdev);
135
136	clear_bit(0, &smo8800->misc_opened); /* release the device */
137	return 0;
138}
139
140static const struct file_operations smo8800_misc_fops = {
141	.owner = THIS_MODULE,
142	.read = smo8800_misc_read,
143	.open = smo8800_misc_open,
144	.release = smo8800_misc_release,
145};
146
147static int smo8800_add(struct acpi_device *device)
148{
149	int err;
150	struct smo8800_device *smo8800;
151
152	smo8800 = devm_kzalloc(&device->dev, sizeof(*smo8800), GFP_KERNEL);
153	if (!smo8800) {
154		dev_err(&device->dev, "failed to allocate device data\n");
155		return -ENOMEM;
156	}
157
158	smo8800->dev = &device->dev;
159	smo8800->miscdev.minor = MISC_DYNAMIC_MINOR;
160	smo8800->miscdev.name = "freefall";
161	smo8800->miscdev.fops = &smo8800_misc_fops;
162
163	init_waitqueue_head(&smo8800->misc_wait);
164
165	err = misc_register(&smo8800->miscdev);
166	if (err) {
167		dev_err(&device->dev, "failed to register misc dev: %d\n", err);
168		return err;
169	}
170
171	device->driver_data = smo8800;
172
173	smo8800->irq = smo8800_get_irq(device);
174	if (!smo8800->irq) {
175		dev_err(&device->dev, "failed to obtain IRQ\n");
176		err = -EINVAL;
177		goto error;
178	}
179
180	err = request_threaded_irq(smo8800->irq, smo8800_interrupt_quick,
181				   smo8800_interrupt_thread,
182				   IRQF_TRIGGER_RISING | IRQF_ONESHOT,
183				   DRIVER_NAME, smo8800);
184	if (err) {
185		dev_err(&device->dev,
186			"failed to request thread for IRQ %d: %d\n",
187			smo8800->irq, err);
188		goto error;
189	}
190
191	dev_dbg(&device->dev, "device /dev/freefall registered with IRQ %d\n",
192		 smo8800->irq);
193	return 0;
194
195error:
196	misc_deregister(&smo8800->miscdev);
197	return err;
198}
199
200static int smo8800_remove(struct acpi_device *device)
201{
202	struct smo8800_device *smo8800 = device->driver_data;
203
204	free_irq(smo8800->irq, smo8800);
205	misc_deregister(&smo8800->miscdev);
206	dev_dbg(&device->dev, "device /dev/freefall unregistered\n");
207	return 0;
208}
209
210static const struct acpi_device_id smo8800_ids[] = {
211	{ "SMO8800", 0 },
212	{ "SMO8801", 0 },
213	{ "SMO8810", 0 },
214	{ "SMO8811", 0 },
215	{ "SMO8820", 0 },
216	{ "SMO8821", 0 },
217	{ "SMO8830", 0 },
218	{ "SMO8831", 0 },
219	{ "", 0 },
220};
221
222MODULE_DEVICE_TABLE(acpi, smo8800_ids);
223
224static struct acpi_driver smo8800_driver = {
225	.name = DRIVER_NAME,
226	.class = "Latitude",
227	.ids = smo8800_ids,
228	.ops = {
229		.add = smo8800_add,
230		.remove = smo8800_remove,
231	},
232	.owner = THIS_MODULE,
233};
234
235module_acpi_driver(smo8800_driver);
236
237MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)");
238MODULE_LICENSE("GPL");
239MODULE_AUTHOR("Sonal Santan, Pali Rohár");