// SPDX-License-Identifier: GPL-2.0-only
/*
 *  Silicon Labs C2 port Linux support for Eurotech Duramar 2150
 *
 *  Copyright (c) 2008 Rodolfo Giometti <giometti@linux.it>
 *  Copyright (c) 2008 Eurotech S.p.A. <info@eurotech.it>
 */

#include <linux/errno.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/ioport.h>
#include <linux/c2port.h>

#define DATA_PORT       0x325
#define DIR_PORT        0x326
#define    C2D             (1 << 0)
#define    C2CK            (1 << 1)

static DEFINE_MUTEX(update_lock);

/*
 * C2 port operations
 */

static void duramar2150_c2port_access(struct c2port_device *dev, int status)
{
        u8 v;

        mutex_lock(&update_lock);

        v = inb(DIR_PORT);

        /* 0 = input, 1 = output */
        if (status)
                outb(v | (C2D | C2CK), DIR_PORT);
        else
                /* When access is "off" is important that both lines are set
                 * as inputs or hi-impedance */
                outb(v & ~(C2D | C2CK), DIR_PORT);

        mutex_unlock(&update_lock);
}

static void duramar2150_c2port_c2d_dir(struct c2port_device *dev, int dir)
{
        u8 v;

        mutex_lock(&update_lock);

        v = inb(DIR_PORT);

        if (dir)
                outb(v & ~C2D, DIR_PORT);
        else
                outb(v | C2D, DIR_PORT);

        mutex_unlock(&update_lock);
}

static int duramar2150_c2port_c2d_get(struct c2port_device *dev)
{
        return inb(DATA_PORT) & C2D;
}

static void duramar2150_c2port_c2d_set(struct c2port_device *dev, int status)
{
        u8 v;

        mutex_lock(&update_lock);

        v = inb(DATA_PORT);

        if (status)
                outb(v | C2D, DATA_PORT);
        else
                outb(v & ~C2D, DATA_PORT);

        mutex_unlock(&update_lock);
}

static void duramar2150_c2port_c2ck_set(struct c2port_device *dev, int status)
{
        u8 v;

        mutex_lock(&update_lock);

        v = inb(DATA_PORT);

        if (status)
                outb(v | C2CK, DATA_PORT);
        else
                outb(v & ~C2CK, DATA_PORT);

        mutex_unlock(&update_lock);
}

static struct c2port_ops duramar2150_c2port_ops = {
        .block_size     = 512,  /* bytes */
        .blocks_num     = 30,   /* total flash size: 15360 bytes */

        .access         = duramar2150_c2port_access,
        .c2d_dir        = duramar2150_c2port_c2d_dir,
        .c2d_get        = duramar2150_c2port_c2d_get,
        .c2d_set        = duramar2150_c2port_c2d_set,
        .c2ck_set       = duramar2150_c2port_c2ck_set,
};

static struct c2port_device *duramar2150_c2port_dev;

/*
 * Module stuff
 */

static int __init duramar2150_c2port_init(void)
{
        struct resource *res;
        int ret = 0;

        res = request_region(0x325, 2, "c2port");
        if (!res)
                return -EBUSY;

        duramar2150_c2port_dev = c2port_device_register("uc",
                                        &duramar2150_c2port_ops, NULL);
        if (IS_ERR(duramar2150_c2port_dev)) {
                ret = PTR_ERR(duramar2150_c2port_dev);
                goto free_region;
        }

        return 0;

free_region:
        release_region(0x325, 2);
        return ret;
}

static void __exit duramar2150_c2port_exit(void)
{
        /* Setup the GPIOs as input by default (access = 0) */
        duramar2150_c2port_access(duramar2150_c2port_dev, 0);

        c2port_device_unregister(duramar2150_c2port_dev);

        release_region(0x325, 2);
}

module_init(duramar2150_c2port_init);
module_exit(duramar2150_c2port_exit);

MODULE_AUTHOR("Rodolfo Giometti <giometti@linux.it>");
MODULE_DESCRIPTION("Silicon Labs C2 port Linux support for Duramar 2150");
MODULE_LICENSE("GPL");