1 // SPDX-License-Identifier: GPL-2.0-only 2 /* linux/drivers/char/scx200_gpio.c 3 4 National Semiconductor SCx200 GPIO driver. Allows a user space 5 process to play with the GPIO pins. 6 7 Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> */ 8 9 #include <linux/device.h> 10 #include <linux/fs.h> 11 #include <linux/module.h> 12 #include <linux/errno.h> 13 #include <linux/kernel.h> 14 #include <linux/init.h> 15 #include <linux/platform_device.h> 16 #include <linux/uaccess.h> 17 #include <asm/io.h> 18 19 #include <linux/types.h> 20 #include <linux/cdev.h> 21 22 #include <linux/scx200_gpio.h> 23 #include <linux/nsc_gpio.h> 24 25 #define DRVNAME "scx200_gpio" 26 27 static struct platform_device *pdev; 28 29 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>"); 30 MODULE_DESCRIPTION("NatSemi/AMD SCx200 GPIO Pin Driver"); 31 MODULE_LICENSE("GPL"); 32 33 static int major = 0; /* default to dynamic major */ 34 module_param(major, int, 0); 35 MODULE_PARM_DESC(major, "Major device number"); 36 37 #define MAX_PINS 32 /* 64 later, when known ok */ 38 39 struct nsc_gpio_ops scx200_gpio_ops = { 40 .owner = THIS_MODULE, 41 .gpio_config = scx200_gpio_configure, 42 .gpio_dump = nsc_gpio_dump, 43 .gpio_get = scx200_gpio_get, 44 .gpio_set = scx200_gpio_set, 45 .gpio_change = scx200_gpio_change, 46 .gpio_current = scx200_gpio_current 47 }; 48 EXPORT_SYMBOL_GPL(scx200_gpio_ops); 49 50 static int scx200_gpio_open(struct inode *inode, struct file *file) 51 { 52 unsigned m = iminor(inode); 53 file->private_data = &scx200_gpio_ops; 54 55 if (m >= MAX_PINS) 56 return -EINVAL; 57 return nonseekable_open(inode, file); 58 } 59 60 static int scx200_gpio_release(struct inode *inode, struct file *file) 61 { 62 return 0; 63 } 64 65 static const struct file_operations scx200_gpio_fileops = { 66 .owner = THIS_MODULE, 67 .write = nsc_gpio_write, 68 .read = nsc_gpio_read, 69 .open = scx200_gpio_open, 70 .release = scx200_gpio_release, 71 .llseek = no_llseek, 72 }; 73 74 static struct cdev scx200_gpio_cdev; /* use 1 cdev for all pins */ 75 76 static int __init scx200_gpio_init(void) 77 { 78 int rc; 79 dev_t devid; 80 81 if (!scx200_gpio_present()) { 82 printk(KERN_ERR DRVNAME ": no SCx200 gpio present\n"); 83 return -ENODEV; 84 } 85 86 /* support dev_dbg() with pdev->dev */ 87 pdev = platform_device_alloc(DRVNAME, 0); 88 if (!pdev) 89 return -ENOMEM; 90 91 rc = platform_device_add(pdev); 92 if (rc) 93 goto undo_malloc; 94 95 /* nsc_gpio uses dev_dbg(), so needs this */ 96 scx200_gpio_ops.dev = &pdev->dev; 97 98 if (major) { 99 devid = MKDEV(major, 0); 100 rc = register_chrdev_region(devid, MAX_PINS, "scx200_gpio"); 101 } else { 102 rc = alloc_chrdev_region(&devid, 0, MAX_PINS, "scx200_gpio"); 103 major = MAJOR(devid); 104 } 105 if (rc < 0) { 106 dev_err(&pdev->dev, "SCx200 chrdev_region err: %d\n", rc); 107 goto undo_platform_device_add; 108 } 109 110 cdev_init(&scx200_gpio_cdev, &scx200_gpio_fileops); 111 cdev_add(&scx200_gpio_cdev, devid, MAX_PINS); 112 113 return 0; /* succeed */ 114 115 undo_platform_device_add: 116 platform_device_del(pdev); 117 undo_malloc: 118 platform_device_put(pdev); 119 120 return rc; 121 } 122 123 static void __exit scx200_gpio_cleanup(void) 124 { 125 cdev_del(&scx200_gpio_cdev); 126 /* cdev_put(&scx200_gpio_cdev); */ 127 128 unregister_chrdev_region(MKDEV(major, 0), MAX_PINS); 129 platform_device_unregister(pdev); 130 } 131 132 module_init(scx200_gpio_init); 133 module_exit(scx200_gpio_cleanup); 134