// SPDX-License-Identifier: GPL-2.0-only
/* 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 <wingel@nano-system.com>
   Copyright (c) 2005      Jim Cromie <jim.cromie@gmail.com>
*/

#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 <linux/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_inode(file));
        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_inode(file));
        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 <jim.cromie@gmail.com>");
MODULE_DESCRIPTION("NatSemi GPIO Common Methods");
MODULE_LICENSE("GPL");