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 byte_data = min_t(u32, data, 255); 71 72 if (put_user(byte_data, buf)) 73 retval = -EFAULT; 74 75 return retval; 76 } 77 78 static 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 90 static 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 99 static 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 }; 105 106 static 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; 151 152 error: 153 misc_deregister(&smo8800->miscdev); 154 return err; 155 } 156 157 static 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 */ 167 static 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 }; 178 MODULE_DEVICE_TABLE(acpi, smo8800_ids); 179 180 static 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 }; 188 module_platform_driver(smo8800_driver); 189 190 MODULE_DESCRIPTION("Dell Latitude freefall driver (ACPI SMO88XX)"); 191 MODULE_LICENSE("GPL"); 192 MODULE_AUTHOR("Sonal Santan, Pali Rohár"); 193