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/config.h>
   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 <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 NAME "scx200_gpio"
  26 #define DEVNAME NAME
  27
  28 static struct platform_device *pdev;
  29
  30 MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
  31 MODULE_DESCRIPTION("NatSemi SCx200 GPIO Pin Driver");
  32 MODULE_LICENSE("GPL");
  33
  34 static int major = 0;           /* default to dynamic major */
  35 module_param(major, int, 0);
  36 MODULE_PARM_DESC(major, "Major device number");
  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
  50 static int scx200_gpio_open(struct inode *inode, struct file *file)
  51 {
  52         unsigned m = iminor(inode);
  53         file->private_data = &scx200_access;
  54
  55         if (m > 63)
  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
  66 static const struct file_operations scx200_gpio_fops = {
  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 struct cdev *scx200_devices;
  75 static int num_pins = 32;
  76
  77 static int __init scx200_gpio_init(void)
  78 {
  79         int rc, i;
  80         dev_t dev = MKDEV(major, 0);
  81
  82         if (!scx200_gpio_present()) {
  83                 printk(KERN_ERR NAME ": no SCx200 gpio present\n");
  84                 return -ENODEV;
  85         }
  86
  87         /* support dev_dbg() with pdev->dev */
  88         pdev = platform_device_alloc(DEVNAME, 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                 rc = register_chrdev_region(dev, num_pins, "scx200_gpio");
 101         else {
 102                 rc = alloc_chrdev_region(&dev, 0, num_pins, "scx200_gpio");
 103                 major = MAJOR(dev);
 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         scx200_devices = kzalloc(num_pins * sizeof(struct cdev), GFP_KERNEL);
 110         if (!scx200_devices) {
 111                 rc = -ENOMEM;
 112                 goto undo_chrdev_region;
 113         }
 114         for (i = 0; i < num_pins; i++) {
 115                 struct cdev *cdev = &scx200_devices[i];
 116                 cdev_init(cdev, &scx200_gpio_fops);
 117                 cdev->owner = THIS_MODULE;
 118                 rc = cdev_add(cdev, MKDEV(major, i), 1);
 119                 /* tolerate 'minor' errors */
 120                 if (rc)
 121                         dev_err(&pdev->dev, "Error %d on minor %d", rc, i);
 122         }
 123
 124         return 0; /* succeed */
 125
 126 undo_chrdev_region:
 127         unregister_chrdev_region(dev, num_pins);
 128 undo_platform_device_add:
 129         platform_device_del(pdev);
 130 undo_malloc:
 131         platform_device_put(pdev);
 132
 133         return rc;
 134 }
 135
 136 static void __exit scx200_gpio_cleanup(void)
 137 {
 138         kfree(scx200_devices);
 139         unregister_chrdev_region(MKDEV(major, 0), num_pins);
 140         platform_device_unregister(pdev);
 141         /* kfree(pdev); */
 142 }
 143
 144 module_init(scx200_gpio_init);
 145 module_exit(scx200_gpio_cleanup);