nsc_gpio.c

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/* linux/drivers/char/nsc_gpio.c

   National Semiconductor common GPIO device-file/VFS methods.
   Allows a user space process to control the GPIO pins.

   Copyright (c) 2001,2002 Christer Weinigel <[email protected]>
   Copyright (c) 2005      Jim Cromie <[email protected]>
*/

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

#define NAME "nsc_gpio"

void nsc_gpio_dump(struct nsc_gpio_ops *amp, unsigned index)
{
    /* retrieve current config w/o changing it */
    u32 config = amp->gpio_config(index, ~0, 0);

    /* user requested via 'v' command, so its INFO */
    dev_info(amp->dev, "io%02u: 0x%04x %s %s %s %s %s %s %s\tio:%d/%d\n",
         index, config,
         (config & 1) ? "OE" : "TS",      /* output-enabled/tristate */
         (config & 2) ? "PP" : "OD",      /* push pull / open drain */
         (config & 4) ? "PUE" : "PUD",    /* pull up enabled/disabled */
         (config & 8) ? "LOCKED" : "",    /* locked / unlocked */
         (config & 16) ? "LEVEL" : "EDGE",/* level/edge input */
         (config & 32) ? "HI" : "LO",     /* trigger on rise/fall edge */
         (config & 64) ? "DEBOUNCE" : "", /* debounce */

         amp->gpio_get(index), amp->gpio_current(index));
}

ssize_t nsc_gpio_write(struct file *file, const char __user *data,
               size_t len, loff_t *ppos)
{
    unsigned m = iminor(file->f_path.dentry->d_inode);
    struct nsc_gpio_ops *amp = file->private_data;
    struct device *dev = amp->dev;
    size_t i;
    int err = 0;

    for (i = 0; i < len; ++i) {
        char c;
        if (get_user(c, data + i))
            return -EFAULT;
        switch (c) {
        case '0':
            amp->gpio_set(m, 0);
            break;
        case '1':
            amp->gpio_set(m, 1);
            break;
        case 'O':
            dev_dbg(dev, "GPIO%d output enabled\n", m);
            amp->gpio_config(m, ~1, 1);
            break;
        case 'o':
            dev_dbg(dev, "GPIO%d output disabled\n", m);
            amp->gpio_config(m, ~1, 0);
            break;
        case 'T':
            dev_dbg(dev, "GPIO%d output is push pull\n", m);
            amp->gpio_config(m, ~2, 2);
            break;
        case 't':
            dev_dbg(dev, "GPIO%d output is open drain\n", m);
            amp->gpio_config(m, ~2, 0);
            break;
        case 'P':
            dev_dbg(dev, "GPIO%d pull up enabled\n", m);
            amp->gpio_config(m, ~4, 4);
            break;
        case 'p':
            dev_dbg(dev, "GPIO%d pull up disabled\n", m);
            amp->gpio_config(m, ~4, 0);
            break;
        case 'v':
            /* View Current pin settings */
            amp->gpio_dump(amp, m);
            break;
        case '\n':
            /* end of settings string, do nothing */
            break;
        default:
            dev_err(dev, "io%2d bad setting: chr<0x%2x>\n",
                m, (int)c);
            err++;
        }
    }
    if (err)
        return -EINVAL; /* full string handled, report error */

    return len;
}

ssize_t nsc_gpio_read(struct file *file, char __user * buf,
              size_t len, loff_t * ppos)
{
    unsigned m = iminor(file->f_path.dentry->d_inode);
    int value;
    struct nsc_gpio_ops *amp = file->private_data;

    value = amp->gpio_get(m);
    if (put_user(value ? '1' : '0', buf))
        return -EFAULT;

    return 1;
}

/* common file-ops routines for both scx200_gpio and pc87360_gpio */
EXPORT_SYMBOL(nsc_gpio_write);
EXPORT_SYMBOL(nsc_gpio_read);
EXPORT_SYMBOL(nsc_gpio_dump);

static int __init nsc_gpio_init(void)
{
    printk(KERN_DEBUG NAME " initializing\n");
    return 0;
}

static void __exit nsc_gpio_cleanup(void)
{
    printk(KERN_DEBUG NAME " cleanup\n");
}

module_init(nsc_gpio_init);
module_exit(nsc_gpio_cleanup);

MODULE_AUTHOR("Jim Cromie <[email protected]>");
MODULE_DESCRIPTION("NatSemi GPIO Common Methods");
MODULE_LICENSE("GPL");