scx200_gpio.c

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/* 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 <[email protected]> */

#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 <[email protected]>");
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,
    .llseek  = no_llseek,
};

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);