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_access = {
  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_set_high  = scx200_gpio_set_high,
  45         .gpio_set_low   = scx200_gpio_set_low,
  46         .gpio_change    = scx200_gpio_change,
  47         .gpio_current   = scx200_gpio_current
  48 };
  49 EXPORT_SYMBOL(scx200_access);
  50
  51 static int scx200_gpio_open(struct inode *inode, struct file *file)
  52 {
  53         unsigned m = iminor(inode);
  54         file->private_data = &scx200_access;
  55
  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
  67 static const struct file_operations scx200_gpio_fops = {
  68         .owner   = THIS_MODULE,
  69         .write   = nsc_gpio_write,
  70         .read    = nsc_gpio_read,
  71         .open    = scx200_gpio_open,
  72         .release = scx200_gpio_release,
  73 };
  74
  75 struct cdev *scx200_devices;
  76
  77 static int __init scx200_gpio_init(void)
  78 {
  79         int rc, i;
  80         dev_t devid;
  81
  82         if (!scx200_gpio_present()) {
  83                 printk(KERN_ERR DRVNAME ": no SCx200 gpio present\n");
  84                 return -ENODEV;
  85         }
  86
  87         /* support dev_dbg() with pdev->dev */
  88         pdev = platform_device_alloc(DRVNAME, 0);
  89         if (!pdev)
  90                 return -ENOMEM;
  91
  92         rc = platform_device_add(pdev);
  93         if (rc)
  94                 goto undo_malloc;
  95
  96         /* nsc_gpio uses dev_dbg(), so needs this */
  97         scx200_access.dev = &pdev->dev;
  98
  99         if (major) {
 100                 devid = MKDEV(major, 0);
 101                 rc = register_chrdev_region(devid, MAX_PINS, "scx200_gpio");
 102         } else {
 103                 rc = alloc_chrdev_region(&devid, 0, MAX_PINS, "scx200_gpio");
 104                 major = MAJOR(devid);
 105         }
 106         if (rc < 0) {
 107                 dev_err(&pdev->dev, "SCx200 chrdev_region err: %d\n", rc);
 108                 goto undo_platform_device_add;
 109         }
 110         scx200_devices = kzalloc(MAX_PINS * sizeof(struct cdev), GFP_KERNEL);
 111         if (!scx200_devices) {
 112                 rc = -ENOMEM;
 113                 goto undo_chrdev_region;
 114         }
 115         for (i = 0; i < MAX_PINS; i++) {
 116                 struct cdev *cdev = &scx200_devices[i];
 117                 cdev_init(cdev, &scx200_gpio_fops);
 118                 cdev->owner = THIS_MODULE;
 119                 rc = cdev_add(cdev, MKDEV(major, i), 1);
 120                 /* tolerate 'minor' errors */
 121                 if (rc)
 122                         dev_err(&pdev->dev, "Error %d on minor %d", rc, i);
 123         }
 124
 125         return 0; /* succeed */
 126
 127 undo_chrdev_region:
 128         unregister_chrdev_region(devid, MAX_PINS);
 129 undo_platform_device_add:
 130         platform_device_del(pdev);
 131 undo_malloc:
 132         platform_device_put(pdev);
 133
 134         return rc;
 135 }
 136
 137 static void __exit scx200_gpio_cleanup(void)
 138 {
 139         kfree(scx200_devices);
 140         unregister_chrdev_region(MKDEV(major, 0), MAX_PINS);
 141         platform_device_unregister(pdev);
 142 }
 143
 144 module_init(scx200_gpio_init);
 145 module_exit(scx200_gpio_cleanup);