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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * dell-smo8800.c - Dell Latitude ACPI SMO88XX freefall sensor driver4 *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 byte_data = min_t(u32, data, 255);71 72 if (put_user(byte_data, buf))73 retval = -EFAULT;74 75 return retval;76}77 78static 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(0, &smo8800->misc_opened))84 return -EBUSY; /* already open */85 86 atomic_set(&smo8800->counter, 0);87 return 0;88}89 90static 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(0, &smo8800->misc_opened); /* release the device */96 return 0;97}98 99static 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 106static int smo8800_probe(struct platform_device *device)107{108 int err;109 struct smo8800_device *smo8800;110 111 smo8800 = devm_kzalloc(&device->dev, 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(&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(device, 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(smo8800->irq, smo8800_interrupt_quick,138 smo8800_interrupt_thread,139 IRQF_TRIGGER_RISING | IRQF_ONESHOT,140 DRIVER_NAME, 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 152error:153 misc_deregister(&smo8800->miscdev);154 return err;155}156 157static void smo8800_remove(struct platform_device *device)158{159 struct smo8800_device *smo8800 = platform_get_drvdata(device);160 161 free_irq(smo8800->irq, smo8800);162 misc_deregister(&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 */167static 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};178MODULE_DEVICE_TABLE(acpi, smo8800_ids);179 180static 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};188module_platform_driver(smo8800_driver);189 190MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)");191MODULE_LICENSE("GPL");192MODULE_AUTHOR("Sonal Santan, Pali Rohár");193