drivers/char/scx200_gpio.c

   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 };
  72
  73 static struct cdev scx200_gpio_cdev;  /* use 1 cdev for all pins */
  74
  75 static int __init scx200_gpio_init(void)
  76 {
  77         int rc;
  78         dev_t devid;
  79
  80         if (!scx200_gpio_present()) {
  81                 printk(KERN_ERR DRVNAME ": no SCx200 gpio present\n");
  82                 return -ENODEV;
  83         }
  84
  85         /* support dev_dbg() with pdev->dev */
  86         pdev = platform_device_alloc(DRVNAME, 0);
  87         if (!pdev)
  88                 return -ENOMEM;
  89
  90         rc = platform_device_add(pdev);
  91         if (rc)
  92                 goto undo_malloc;
  93
  94         /* nsc_gpio uses dev_dbg(), so needs this */
  95         scx200_gpio_ops.dev = &pdev->dev;
  96
  97         if (major) {
  98                 devid = MKDEV(major, 0);
  99                 rc = register_chrdev_region(devid, MAX_PINS, "scx200_gpio");
 100         } else {
 101                 rc = alloc_chrdev_region(&devid, 0, MAX_PINS, "scx200_gpio");
 102                 major = MAJOR(devid);
 103         }
 104         if (rc < 0) {
 105                 dev_err(&pdev->dev, "SCx200 chrdev_region err: %d\n", rc);
 106                 goto undo_platform_device_add;
 107         }
 108
 109         cdev_init(&scx200_gpio_cdev, &scx200_gpio_fileops);
 110         cdev_add(&scx200_gpio_cdev, devid, MAX_PINS);
 111
 112         return 0; /* succeed */
 113
 114 undo_platform_device_add:
 115         platform_device_del(pdev);
 116 undo_malloc:
 117         platform_device_put(pdev);
 118
 119         return rc;
 120 }
 121
 122 static void __exit scx200_gpio_cleanup(void)
 123 {
 124         cdev_del(&scx200_gpio_cdev);
 125         /* cdev_put(&scx200_gpio_cdev); */
 126
 127         unregister_chrdev_region(MKDEV(major, 0), MAX_PINS);
 128         platform_device_unregister(pdev);
 129 }
 130
 131 module_init(scx200_gpio_init);
 132 module_exit(scx200_gpio_cleanup);