![Colin Ian King](/assets/img/avatar_default.png)
Variable byte_data is being initialized and re-assigned with values that are never read. Remove these as these redundant assignments. Cleans up clang warning: drivers/platform/x86/dell-smo8800.c:106:2: warning: Value stored to 'byte_data' is never read Signed-off-by: Colin Ian King <colin.king@canonical.com> Acked-by: Pali Rohár <pali.rohar@gmail.com> Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
240 lines
5.8 KiB
C
240 lines
5.8 KiB
C
/*
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* dell-smo8800.c - Dell Latitude ACPI SMO88XX freefall sensor driver
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*
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* Copyright (C) 2012 Sonal Santan <sonal.santan@gmail.com>
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* Copyright (C) 2014 Pali Rohár <pali.rohar@gmail.com>
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*
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* This is loosely based on lis3lv02d driver.
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#define DRIVER_NAME "smo8800"
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/acpi.h>
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#include <linux/interrupt.h>
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#include <linux/miscdevice.h>
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#include <linux/uaccess.h>
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struct smo8800_device {
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u32 irq; /* acpi device irq */
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atomic_t counter; /* count after last read */
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struct miscdevice miscdev; /* for /dev/freefall */
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unsigned long misc_opened; /* whether the device is open */
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wait_queue_head_t misc_wait; /* Wait queue for the misc dev */
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struct device *dev; /* acpi device */
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};
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static irqreturn_t smo8800_interrupt_quick(int irq, void *data)
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{
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struct smo8800_device *smo8800 = data;
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atomic_inc(&smo8800->counter);
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wake_up_interruptible(&smo8800->misc_wait);
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return IRQ_WAKE_THREAD;
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}
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static irqreturn_t smo8800_interrupt_thread(int irq, void *data)
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{
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struct smo8800_device *smo8800 = data;
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dev_info(smo8800->dev, "detected free fall\n");
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return IRQ_HANDLED;
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}
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static acpi_status smo8800_get_resource(struct acpi_resource *resource,
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void *context)
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{
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struct acpi_resource_extended_irq *irq;
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if (resource->type != ACPI_RESOURCE_TYPE_EXTENDED_IRQ)
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return AE_OK;
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irq = &resource->data.extended_irq;
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if (!irq || !irq->interrupt_count)
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return AE_OK;
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*((u32 *)context) = irq->interrupts[0];
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return AE_CTRL_TERMINATE;
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}
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static u32 smo8800_get_irq(struct acpi_device *device)
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{
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u32 irq = 0;
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acpi_status status;
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status = acpi_walk_resources(device->handle, METHOD_NAME__CRS,
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smo8800_get_resource, &irq);
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if (ACPI_FAILURE(status)) {
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dev_err(&device->dev, "acpi_walk_resources failed\n");
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return 0;
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}
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return irq;
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}
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static ssize_t smo8800_misc_read(struct file *file, char __user *buf,
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size_t count, loff_t *pos)
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{
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struct smo8800_device *smo8800 = container_of(file->private_data,
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struct smo8800_device, miscdev);
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u32 data = 0;
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unsigned char byte_data;
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ssize_t retval = 1;
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if (count < 1)
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return -EINVAL;
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atomic_set(&smo8800->counter, 0);
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retval = wait_event_interruptible(smo8800->misc_wait,
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(data = atomic_xchg(&smo8800->counter, 0)));
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if (retval)
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return retval;
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retval = 1;
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if (data < 255)
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byte_data = data;
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else
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byte_data = 255;
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if (put_user(byte_data, buf))
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retval = -EFAULT;
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return retval;
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}
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static int smo8800_misc_open(struct inode *inode, struct file *file)
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{
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struct smo8800_device *smo8800 = container_of(file->private_data,
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struct smo8800_device, miscdev);
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if (test_and_set_bit(0, &smo8800->misc_opened))
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return -EBUSY; /* already open */
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atomic_set(&smo8800->counter, 0);
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return 0;
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}
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static int smo8800_misc_release(struct inode *inode, struct file *file)
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{
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struct smo8800_device *smo8800 = container_of(file->private_data,
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struct smo8800_device, miscdev);
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clear_bit(0, &smo8800->misc_opened); /* release the device */
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return 0;
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}
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static const struct file_operations smo8800_misc_fops = {
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.owner = THIS_MODULE,
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.read = smo8800_misc_read,
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.open = smo8800_misc_open,
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.release = smo8800_misc_release,
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};
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static int smo8800_add(struct acpi_device *device)
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{
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int err;
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struct smo8800_device *smo8800;
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smo8800 = devm_kzalloc(&device->dev, sizeof(*smo8800), GFP_KERNEL);
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if (!smo8800) {
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dev_err(&device->dev, "failed to allocate device data\n");
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return -ENOMEM;
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}
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smo8800->dev = &device->dev;
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smo8800->miscdev.minor = MISC_DYNAMIC_MINOR;
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smo8800->miscdev.name = "freefall";
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smo8800->miscdev.fops = &smo8800_misc_fops;
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init_waitqueue_head(&smo8800->misc_wait);
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err = misc_register(&smo8800->miscdev);
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if (err) {
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dev_err(&device->dev, "failed to register misc dev: %d\n", err);
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return err;
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}
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device->driver_data = smo8800;
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smo8800->irq = smo8800_get_irq(device);
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if (!smo8800->irq) {
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dev_err(&device->dev, "failed to obtain IRQ\n");
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err = -EINVAL;
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goto error;
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}
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err = request_threaded_irq(smo8800->irq, smo8800_interrupt_quick,
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smo8800_interrupt_thread,
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IRQF_TRIGGER_RISING | IRQF_ONESHOT,
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DRIVER_NAME, smo8800);
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if (err) {
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dev_err(&device->dev,
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"failed to request thread for IRQ %d: %d\n",
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smo8800->irq, err);
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goto error;
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}
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dev_dbg(&device->dev, "device /dev/freefall registered with IRQ %d\n",
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smo8800->irq);
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return 0;
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error:
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misc_deregister(&smo8800->miscdev);
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return err;
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}
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static int smo8800_remove(struct acpi_device *device)
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{
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struct smo8800_device *smo8800 = device->driver_data;
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free_irq(smo8800->irq, smo8800);
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misc_deregister(&smo8800->miscdev);
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dev_dbg(&device->dev, "device /dev/freefall unregistered\n");
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return 0;
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}
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static const struct acpi_device_id smo8800_ids[] = {
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{ "SMO8800", 0 },
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{ "SMO8801", 0 },
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{ "SMO8810", 0 },
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{ "SMO8811", 0 },
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{ "SMO8820", 0 },
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{ "SMO8821", 0 },
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{ "SMO8830", 0 },
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{ "SMO8831", 0 },
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{ "", 0 },
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};
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MODULE_DEVICE_TABLE(acpi, smo8800_ids);
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static struct acpi_driver smo8800_driver = {
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.name = DRIVER_NAME,
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.class = "Latitude",
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.ids = smo8800_ids,
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.ops = {
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.add = smo8800_add,
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.remove = smo8800_remove,
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},
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.owner = THIS_MODULE,
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};
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module_acpi_driver(smo8800_driver);
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MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)");
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Sonal Santan, Pali Rohár");
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