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"); 197