// SPDX-License-Identifier: GPL-2.0
/*
 * /dev/lcd driver for Apple Network Servers.
 */

#include <linux/types.h>
#include <linux/errno.h>
#include <linux/kernel.h>
#include <linux/miscdevice.h>
#include <linux/fcntl.h>
#include <linux/module.h>
#include <linux/delay.h>
#include <linux/fs.h>
#include <linux/of.h>

#include <linux/uaccess.h>
#include <asm/sections.h>
#include <asm/io.h>

#include "ans-lcd.h"

#define ANSLCD_ADDR             0xf301c000
#define ANSLCD_CTRL_IX 0x00
#define ANSLCD_DATA_IX 0x10

static unsigned long anslcd_short_delay = 80;
static unsigned long anslcd_long_delay = 3280;
static volatile unsigned char __iomem *anslcd_ptr;
static DEFINE_MUTEX(anslcd_mutex);

#undef DEBUG

static void
anslcd_write_byte_ctrl ( unsigned char c )
{
#ifdef DEBUG
        printk(KERN_DEBUG "LCD: CTRL byte: %02x\n",c);
#endif
        out_8(anslcd_ptr + ANSLCD_CTRL_IX, c);
        switch(c) {
                case 1:
                case 2:
                case 3:
                        udelay(anslcd_long_delay); break;
                default: udelay(anslcd_short_delay);
        }
}

static void
anslcd_write_byte_data ( unsigned char c )
{
        out_8(anslcd_ptr + ANSLCD_DATA_IX, c);
        udelay(anslcd_short_delay);
}

static ssize_t
anslcd_write( struct file * file, const char __user * buf, 
                                size_t count, loff_t *ppos )
{
        const char __user *p = buf;
        int i;

#ifdef DEBUG
        printk(KERN_DEBUG "LCD: write\n");
#endif

        if (!access_ok(buf, count))
                return -EFAULT;

        mutex_lock(&anslcd_mutex);
        for ( i = *ppos; count > 0; ++i, ++p, --count ) 
        {
                char c;
                __get_user(c, p);
                anslcd_write_byte_data( c );
        }
        mutex_unlock(&anslcd_mutex);
        *ppos = i;
        return p - buf;
}

static long
anslcd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
        char ch, __user *temp;
        long ret = 0;

#ifdef DEBUG
        printk(KERN_DEBUG "LCD: ioctl(%d,%d)\n",cmd,arg);
#endif

        mutex_lock(&anslcd_mutex);

        switch ( cmd )
        {
        case ANSLCD_CLEAR:
                anslcd_write_byte_ctrl ( 0x38 );
                anslcd_write_byte_ctrl ( 0x0f );
                anslcd_write_byte_ctrl ( 0x06 );
                anslcd_write_byte_ctrl ( 0x01 );
                anslcd_write_byte_ctrl ( 0x02 );
                break;
        case ANSLCD_SENDCTRL:
                temp = (char __user *) arg;
                __get_user(ch, temp);
                for (; ch; temp++) { /* FIXME: This is ugly, but should work, as a \0 byte is not a valid command code */
                        anslcd_write_byte_ctrl ( ch );
                        __get_user(ch, temp);
                }
                break;
        case ANSLCD_SETSHORTDELAY:
                if (!capable(CAP_SYS_ADMIN))
                        ret =-EACCES;
                else
                        anslcd_short_delay=arg;
                break;
        case ANSLCD_SETLONGDELAY:
                if (!capable(CAP_SYS_ADMIN))
                        ret = -EACCES;
                else
                        anslcd_long_delay=arg;
                break;
        default:
                ret = -EINVAL;
        }

        mutex_unlock(&anslcd_mutex);
        return ret;
}

static int
anslcd_open( struct inode * inode, struct file * file )
{
        return 0;
}

const struct file_operations anslcd_fops = {
        .write          = anslcd_write,
        .unlocked_ioctl = anslcd_ioctl,
        .open           = anslcd_open,
        .llseek         = default_llseek,
};

static struct miscdevice anslcd_dev = {
        LCD_MINOR,
        "anslcd",
        &anslcd_fops
};

static const char anslcd_logo[] __initconst =
                                "********************"  /* Line #1 */
                                "*      LINUX!      *"  /* Line #3 */
                                "*    Welcome to    *"  /* Line #2 */
                                "********************"; /* Line #4 */

static int __init
anslcd_init(void)
{
        int a;
        int retval;
        struct device_node* node;

        node = of_find_node_by_name(NULL, "lcd");
        if (!node || !of_node_name_eq(node->parent, "gc")) {
                of_node_put(node);
                return -ENODEV;
        }
        of_node_put(node);

        anslcd_ptr = ioremap(ANSLCD_ADDR, 0x20);
        
        retval = misc_register(&anslcd_dev);
        if(retval < 0){
                printk(KERN_INFO "LCD: misc_register failed\n");
                iounmap(anslcd_ptr);
                return retval;
        }

#ifdef DEBUG
        printk(KERN_DEBUG "LCD: init\n");
#endif

        mutex_lock(&anslcd_mutex);
        anslcd_write_byte_ctrl ( 0x38 );
        anslcd_write_byte_ctrl ( 0x0c );
        anslcd_write_byte_ctrl ( 0x06 );
        anslcd_write_byte_ctrl ( 0x01 );
        anslcd_write_byte_ctrl ( 0x02 );
        for(a=0;a<80;a++) {
                anslcd_write_byte_data(anslcd_logo[a]);
        }
        mutex_unlock(&anslcd_mutex);
        return 0;
}

static void __exit
anslcd_exit(void)
{
        misc_deregister(&anslcd_dev);
        iounmap(anslcd_ptr);
}

module_init(anslcd_init);
module_exit(anslcd_exit);
MODULE_LICENSE("GPL v2");