drivers/char/scx200_gpio.c

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