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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 <wingel@nano-system.com> */

#include <linux/config.h>

#include <linux/module.h>

#include <linux/errno.h>

#include <linux/kernel.h>

#include <linux/init.h>

#include <asm/uaccess.h>

#include <asm/io.h>

#include <linux/scx200_gpio.h>

#define NAME "scx200_gpio"

MODULE_AUTHOR("Christer Weinigel <wingel@nano-system.com>");

MODULE_DESCRIPTION("NatSemi SCx200 GPIO Pin Driver");

MODULE_LICENSE("GPL");

static int major = 0;            /* default to dynamic major */

MODULE_PARM(major, "i");

MODULE_PARM_DESC(major, "Major device number");

static ssize_t scx200_gpio_write(struct file *file, const char *data,

                                 size_t len, loff_t *ppos)

{

        unsigned m = minor(file->f_dentry->d_inode->i_rdev);

        size_t i;

        if (ppos != &file->f_pos)

                return -ESPIPE;

        for (i = 0; i < len; ++i) {

                char c;

                if (get_user(c, data+i))

                        return -EFAULT;

                switch (c)

                {

                case '0':

                        scx200_gpio_set(m, 0);

                        break;

                case '1':

                        scx200_gpio_set(m, 1);

                        break;

                case 'O':

                        printk(KERN_INFO NAME ": GPIO%d output enabled\n", m);

                        scx200_gpio_configure(m, ~1, 1);

                        break;

                case 'o':

                        printk(KERN_INFO NAME ": GPIO%d output disabled\n", m);

                        scx200_gpio_configure(m, ~1, 0);

                        break;

                case 'T':

                        printk(KERN_INFO NAME ": GPIO%d output is push pull\n", m);

                        scx200_gpio_configure(m, ~2, 2);

                        break;

                case 't':

                        printk(KERN_INFO NAME ": GPIO%d output is open drain\n", m);

                        scx200_gpio_configure(m, ~2, 0);

                        break;

                case 'P':

                        printk(KERN_INFO NAME ": GPIO%d pull up enabled\n", m);

                        scx200_gpio_configure(m, ~4, 4);

                        break;

                case 'p':

                        printk(KERN_INFO NAME ": GPIO%d pull up disabled\n", m);

                        scx200_gpio_configure(m, ~4, 0);

                        break;

                }

        }

        return len;

}

static ssize_t scx200_gpio_read(struct file *file, char *buf,

                                size_t len, loff_t *ppos)

{

        unsigned m = minor(file->f_dentry->d_inode->i_rdev);

        int value;

        if (ppos != &file->f_pos)

                return -ESPIPE;

        value = scx200_gpio_get(m);

        if (put_user(value ? '1' : '0', buf))

                return -EFAULT;

        return 1;

}

static int scx200_gpio_open(struct inode *inode, struct file *file)

{

        unsigned m = minor(inode->i_rdev);

        if (m > 63)

                return -EINVAL;

        return 0;

}

static int scx200_gpio_release(struct inode *inode, struct file *file)

{

        return 0;

}

static struct file_operations scx200_gpio_fops = {

        .owner   = THIS_MODULE,

        .write   = scx200_gpio_write,

        .read    = scx200_gpio_read,

        .open    = scx200_gpio_open,

        .release = scx200_gpio_release,

};

static int __init scx200_gpio_init(void)

{

        int r;

        printk(KERN_DEBUG NAME ": NatSemi SCx200 GPIO Driver\n");

        if (!scx200_gpio_present()) {

                printk(KERN_ERR NAME ": no SCx200 gpio pins available\n");

                return -ENODEV;

        }

        r = register_chrdev(major, NAME, &scx200_gpio_fops);

        if (r < 0) {

                printk(KERN_ERR NAME ": unable to register character device\n");

                return r;

        }

        if (!major) {

                major = r;

                printk(KERN_DEBUG NAME ": got dynamic major %d\n", major);

        }

        return 0;

}

static void __exit scx200_gpio_cleanup(void)

{

        unregister_chrdev(major, NAME);

}

module_init(scx200_gpio_init);

module_exit(scx200_gpio_cleanup);

/*

    Local variables:

        compile-command: "make -k -C ../.. SUBDIRS=drivers/char modules"

        c-basic-offset: 8

    End:

*/