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 * linux/drivers/video/n411.c -- Platform device for N411 EPD kit
 * Copyright (C) 2008, Jaya Kumar
 * This file is subject to the terms and conditions of the GNU General Public
 * License. See the file COPYING in the main directory of this archive for
 * more details.
 * Layout is based on skeletonfb.c by James Simmons and Geert Uytterhoeven.
 * This driver is written to be used with the Hecuba display controller
 * board, and tested with the EInk 800x600 display in 1 bit mode.
 * The interface between Hecuba and the host is TTL based GPIO. The
 * GPIO requirements are 8 writable data lines and 6 lines for control.
 * Only 4 of the controls are actually used here but 6 for future use.
 * The driver requires the IO addresses for data and control GPIO at
 * load time. It is also possible to use this display with a standard
 * PC parallel port.
 * General notes:
 * - User must set dio_addr=0xIOADDR cio_addr=0xIOADDR c2io_addr=0xIOADDR

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/delay.h>
#include <linux/interrupt.h>
#include <linux/fb.h>
#include <linux/init.h>
#include <linux/platform_device.h>
#include <linux/list.h>
#include <linux/uaccess.h>
#include <linux/irq.h>

#include <video/hecubafb.h>

static unsigned long dio_addr;
static unsigned long cio_addr;
static unsigned long c2io_addr;
static unsigned long splashval;
static unsigned int nosplash;
static unsigned char ctl;

static void n411_set_ctl(struct hecubafb_par *par, unsigned char bit, unsigned
							char state)
	switch (bit) {
	case HCB_CD_BIT:
		if (state)
			ctl &= ~(HCB_CD_BIT);
			ctl |= HCB_CD_BIT;
	case HCB_DS_BIT:
		if (state)
			ctl &= ~(HCB_DS_BIT);
			ctl |= HCB_DS_BIT;
	outb(ctl, cio_addr);

static unsigned char n411_get_ctl(struct hecubafb_par *par)
	return inb(c2io_addr);

static void n411_set_data(struct hecubafb_par *par, unsigned char value)
	outb(value, dio_addr);

static void n411_wait_for_ack(struct hecubafb_par *par, int clear)
	int timeout;
	unsigned char tmp;

	timeout = 500;
	do {
		tmp = n411_get_ctl(par);
		if ((tmp & HCB_ACK_BIT) && (!clear))
		else if (!(tmp & HCB_ACK_BIT) && (clear))
	} while (timeout--);
	printk(KERN_ERR "timed out waiting for ack\n");

static int n411_init_control(struct hecubafb_par *par)
	unsigned char tmp;
	/* for init, we want the following setup to be set:
	WUP = lo
	ACK = hi
	DS = hi
	RW = hi
	CD = lo

	/* write WUP to lo, DS to hi, RW to hi, CD to lo */
	n411_set_ctl(par, HCB_DS_BIT, 1);

	/* check ACK is not lo */
	tmp = n411_get_ctl(par);
	if (tmp & HCB_ACK_BIT) {
		printk(KERN_ERR "Fail because ACK is already low\n");
		return -ENXIO;

	return 0;

static int n411_init_board(struct hecubafb_par *par)
	int retval;

	retval = n411_init_control(par);
	if (retval)
		return retval;

	par->send_command(par, APOLLO_INIT_DISPLAY);
	par->send_data(par, 0x81);

	/* have to wait while display resets */

	/* if we were told to splash the screen, we just clear it */
	if (!nosplash) {
		par->send_command(par, APOLLO_ERASE_DISPLAY);
		par->send_data(par, splashval);

	return 0;

static struct hecuba_board n411_board = {
	.owner			= THIS_MODULE,
	.init			= n411_init_board,
	.set_ctl		= n411_set_ctl,
	.set_data		= n411_set_data,
	.wait_for_ack		= n411_wait_for_ack,

static struct platform_device *n411_device;
static int __init n411_init(void)
	int ret;
	if (!dio_addr || !cio_addr || !c2io_addr) {
		printk(KERN_WARNING "no IO addresses supplied\n");
		return -EINVAL;

	/* request our platform independent driver */

	n411_device = platform_device_alloc("hecubafb", -1);
	if (!n411_device)
		return -ENOMEM;

	platform_device_add_data(n411_device, &n411_board, sizeof(n411_board));

	/* this _add binds hecubafb to n411. hecubafb refcounts n411 */
	ret = platform_device_add(n411_device);

	if (ret)

	return ret;


static void __exit n411_exit(void)


module_param(nosplash, uint, 0);
MODULE_PARM_DESC(nosplash, "Disable doing the splash screen");
module_param(dio_addr, ulong, 0);
MODULE_PARM_DESC(dio_addr, "IO address for data, eg: 0x480");
module_param(cio_addr, ulong, 0);
MODULE_PARM_DESC(cio_addr, "IO address for control, eg: 0x400");
module_param(c2io_addr, ulong, 0);
MODULE_PARM_DESC(c2io_addr, "IO address for secondary control, eg: 0x408");
module_param(splashval, ulong, 0);
MODULE_PARM_DESC(splashval, "Splash pattern: 0x00 is black, 0x01 is white");

MODULE_DESCRIPTION("board driver for n411 hecuba/apollo epd kit");
MODULE_AUTHOR("Jaya Kumar");