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 <linux/smp_lock.h>
  16 #include <asm/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         cycle_kernel_lock();
  56         if (m >= MAX_PINS)
  57                 return -EINVAL;
  58         return nonseekable_open(inode, file);
  59 }
  60
  61 static int scx200_gpio_release(struct inode *inode, struct file *file)
  62 {
  63         return 0;
  64 }
  65
  66 static const struct file_operations scx200_gpio_fileops = {
  67         .owner   = THIS_MODULE,
  68         .write   = nsc_gpio_write,
  69         .read    = nsc_gpio_read,
  70         .open    = scx200_gpio_open,
  71         .release = scx200_gpio_release,
  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);