drivers/platform/x86/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.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
  20 struct 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
  29 static 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
  38 static 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
  46 static 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
  62 static 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
  77 static 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
 110 static 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
 122 static 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
 131 static 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
 138 static 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
 186 error:
 187         misc_deregister(&smo8800->miscdev);
 188         return err;
 189 }
 190
 191 static 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 */
 202 static 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
 214 MODULE_DEVICE_TABLE(acpi, smo8800_ids);
 215
 216 static 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
 227 module_acpi_driver(smo8800_driver);
 228
 229 MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)");
 230 MODULE_LICENSE("GPL");
 231 MODULE_AUTHOR("Sonal Santan, Pali Rohár");