// 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/uaccess.h>

  #include <asm/sections.h>
  #include <asm/prom.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
  ",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
  ");
  #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)
  ",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
  ");
  		iounmap(anslcd_ptr);
  		return retval;
  	}
  
  #ifdef DEBUG
  	printk(KERN_DEBUG "LCD: init
  ");
  #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");