drivers/platform/x86/dell/dell-smo8800.c

   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/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
  22 struct 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
  31 static 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
  40 static 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
  48 static 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         if (data < 255)
  71                 byte_data = data;
  72         else
  73                 byte_data = 255;
  74
  75         if (put_user(byte_data, buf))
  76                 retval = -EFAULT;
  77
  78         return retval;
  79 }
  80
  81 static int smo8800_misc_open(struct inode *inode, struct file *file)
  82 {
  83         struct smo8800_device *smo8800 = container_of(file->private_data,
  84                                          struct smo8800_device, miscdev);
  85
  86         if (test_and_set_bit(0, &smo8800->misc_opened))
  87                 return -EBUSY; /* already open */
  88
  89         atomic_set(&smo8800->counter, 0);
  90         return 0;
  91 }
  92
  93 static int smo8800_misc_release(struct inode *inode, struct file *file)
  94 {
  95         struct smo8800_device *smo8800 = container_of(file->private_data,
  96                                          struct smo8800_device, miscdev);
  97
  98         clear_bit(0, &smo8800->misc_opened); /* release the device */
  99         return 0;
 100 }
 101
 102 static const struct file_operations smo8800_misc_fops = {
 103         .owner = THIS_MODULE,
 104         .read = smo8800_misc_read,
 105         .open = smo8800_misc_open,
 106         .release = smo8800_misc_release,
 107 };
 108
 109 static int smo8800_probe(struct platform_device *device)
 110 {
 111         int err;
 112         struct smo8800_device *smo8800;
 113
 114         smo8800 = devm_kzalloc(&device->dev, sizeof(*smo8800), GFP_KERNEL);
 115         if (!smo8800) {
 116                 dev_err(&device->dev, "failed to allocate device data\n");
 117                 return -ENOMEM;
 118         }
 119
 120         smo8800->dev = &device->dev;
 121         smo8800->miscdev.minor = MISC_DYNAMIC_MINOR;
 122         smo8800->miscdev.name = "freefall";
 123         smo8800->miscdev.fops = &smo8800_misc_fops;
 124
 125         init_waitqueue_head(&smo8800->misc_wait);
 126
 127         err = misc_register(&smo8800->miscdev);
 128         if (err) {
 129                 dev_err(&device->dev, "failed to register misc dev: %d\n", err);
 130                 return err;
 131         }
 132
 133         platform_set_drvdata(device, smo8800);
 134
 135         err = platform_get_irq(device, 0);
 136         if (err < 0)
 137                 goto error;
 138         smo8800->irq = err;
 139
 140         err = request_threaded_irq(smo8800->irq, smo8800_interrupt_quick,
 141                                    smo8800_interrupt_thread,
 142                                    IRQF_TRIGGER_RISING | IRQF_ONESHOT,
 143                                    DRIVER_NAME, smo8800);
 144         if (err) {
 145                 dev_err(&device->dev,
 146                         "failed to request thread for IRQ %d: %d\n",
 147                         smo8800->irq, err);
 148                 goto error;
 149         }
 150
 151         dev_dbg(&device->dev, "device /dev/freefall registered with IRQ %d\n",
 152                  smo8800->irq);
 153         return 0;
 154
 155 error:
 156         misc_deregister(&smo8800->miscdev);
 157         return err;
 158 }
 159
 160 static int smo8800_remove(struct platform_device *device)
 161 {
 162         struct smo8800_device *smo8800 = platform_get_drvdata(device);
 163
 164         free_irq(smo8800->irq, smo8800);
 165         misc_deregister(&smo8800->miscdev);
 166         dev_dbg(&device->dev, "device /dev/freefall unregistered\n");
 167         return 0;
 168 }
 169
 170 /* NOTE: Keep this list in sync with drivers/i2c/busses/i2c-i801.c */
 171 static const struct acpi_device_id smo8800_ids[] = {
 172         { "SMO8800", 0 },
 173         { "SMO8801", 0 },
 174         { "SMO8810", 0 },
 175         { "SMO8811", 0 },
 176         { "SMO8820", 0 },
 177         { "SMO8821", 0 },
 178         { "SMO8830", 0 },
 179         { "SMO8831", 0 },
 180         { "", 0 },
 181 };
 182 MODULE_DEVICE_TABLE(acpi, smo8800_ids);
 183
 184 static struct platform_driver smo8800_driver = {
 185         .probe = smo8800_probe,
 186         .remove = smo8800_remove,
 187         .driver = {
 188                 .name = DRIVER_NAME,
 189                 .acpi_match_table = smo8800_ids,
 190         },
 191 };
 192 module_platform_driver(smo8800_driver);
 193
 194 MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)");
 195 MODULE_LICENSE("GPL");
 196 MODULE_AUTHOR("Sonal Santan, Pali Rohár");