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scx200_gpio.c

/* linux/drivers/char/scx200_gpio.c

   National Semiconductor SCx200 GPIO driver.  Allows a user space
   process to play with the GPIO pins.

   Copyright (c) 2001,2002 Christer Weinigel <wingel@nano-system.com> */

#include <linux/device.h>
#include <linux/fs.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <asm/uaccess.h>
#include <asm/io.h>

#include <linux/types.h>
#include <linux/cdev.h>

#include <linux/scx200_gpio.h>
#include <linux/nsc_gpio.h>

#define DRVNAME "scx200_gpio"

static struct platform_device *pdev;

MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");
MODULE_DESCRIPTION("NatSemi/AMD SCx200 GPIO Pin Driver");
MODULE_LICENSE("GPL");

static int major = 0;         /* default to dynamic major */
module_param(major, int, 0);
MODULE_PARM_DESC(major, "Major device number");

#define MAX_PINS 32           /* 64 later, when known ok */

struct nsc_gpio_ops scx200_gpio_ops = {
      .owner            = THIS_MODULE,
      .gpio_config      = scx200_gpio_configure,
      .gpio_dump  = nsc_gpio_dump,
      .gpio_get   = scx200_gpio_get,
      .gpio_set   = scx200_gpio_set,
      .gpio_change      = scx200_gpio_change,
      .gpio_current     = scx200_gpio_current
};
EXPORT_SYMBOL_GPL(scx200_gpio_ops);

static int scx200_gpio_open(struct inode *inode, struct file *file)
{
      unsigned m = iminor(inode);
      file->private_data = &scx200_gpio_ops;

      if (m >= MAX_PINS)
            return -EINVAL;
      return nonseekable_open(inode, file);
}

static int scx200_gpio_release(struct inode *inode, struct file *file)
{
      return 0;
}

static const struct file_operations scx200_gpio_fileops = {
      .owner   = THIS_MODULE,
      .write   = nsc_gpio_write,
      .read    = nsc_gpio_read,
      .open    = scx200_gpio_open,
      .release = scx200_gpio_release,
};

static struct cdev scx200_gpio_cdev;  /* use 1 cdev for all pins */

static int __init scx200_gpio_init(void)
{
      int rc;
      dev_t devid;

      if (!scx200_gpio_present()) {
            printk(KERN_ERR DRVNAME ": no SCx200 gpio present\n");
            return -ENODEV;
      }

      /* support dev_dbg() with pdev->dev */
      pdev = platform_device_alloc(DRVNAME, 0);
      if (!pdev)
            return -ENOMEM;

      rc = platform_device_add(pdev);
      if (rc)
            goto undo_malloc;

      /* nsc_gpio uses dev_dbg(), so needs this */
      scx200_gpio_ops.dev = &pdev->dev;

      if (major) {
            devid = MKDEV(major, 0);
            rc = register_chrdev_region(devid, MAX_PINS, "scx200_gpio");
      } else {
            rc = alloc_chrdev_region(&devid, 0, MAX_PINS, "scx200_gpio");
            major = MAJOR(devid);
      }
      if (rc < 0) {
            dev_err(&pdev->dev, "SCx200 chrdev_region err: %d\n", rc);
            goto undo_platform_device_add;
      }

      cdev_init(&scx200_gpio_cdev, &scx200_gpio_fileops);
      cdev_add(&scx200_gpio_cdev, devid, MAX_PINS);

      return 0; /* succeed */

undo_platform_device_add:
      platform_device_del(pdev);
undo_malloc:
      platform_device_put(pdev);

      return rc;
}

static void __exit scx200_gpio_cleanup(void)
{
      cdev_del(&scx200_gpio_cdev);
      /* cdev_put(&scx200_gpio_cdev); */

      unregister_chrdev_region(MKDEV(major, 0), MAX_PINS);
      platform_device_unregister(pdev);
}

module_init(scx200_gpio_init);
module_exit(scx200_gpio_cleanup);

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