/*
 * linux/drivers/video/hecubafb.c -- FB driver for Hecuba controller
 *
 * Copyright (C) 2006, Jaya Kumar
 * This work was sponsored by CIS(M) Sdn Bhd
 *
 * 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 work was possible because of apollo display code from E-Ink's website
 * http://support.eink.com/community
 * All information used to write this code is from public material made
 * available by E-Ink on its support site. Some commands such as 0xA4
 * were found by looping through cmd=0x00 thru 0xFF and supplying random
 * values. There are other commands that the display is capable of,
 * beyond the 5 used here but they are more complex.
 *
 * 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 hecubafb_enable=1 to enable it
 * - 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/mm.h>
#include <linux/slab.h>
#include <linux/vmalloc.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 <asm/uaccess.h>

/* Apollo controller specific defines */
#define APOLLO_START_NEW_IMG	0xA0
#define APOLLO_STOP_IMG_DATA	0xA1
#define APOLLO_DISPLAY_IMG	0xA2
#define APOLLO_ERASE_DISPLAY	0xA3
#define APOLLO_INIT_DISPLAY	0xA4

/* Hecuba interface specific defines */
/* WUP is inverted, CD is inverted, DS is inverted */
#define HCB_NWUP_BIT	0x01
#define HCB_NDS_BIT 	0x02
#define HCB_RW_BIT 	0x04
#define HCB_NCD_BIT 	0x08
#define HCB_ACK_BIT 	0x80

/* Display specific information */
#define DPY_W 600
#define DPY_H 800

struct hecubafb_par {
	unsigned long dio_addr;
	unsigned long cio_addr;
	unsigned long c2io_addr;
	unsigned char ctl;
	struct fb_info *info;
	unsigned int irq;
};

static struct fb_fix_screeninfo hecubafb_fix __devinitdata = {
	.id =		"hecubafb",
	.type =		FB_TYPE_PACKED_PIXELS,
	.visual =	FB_VISUAL_MONO01,
	.xpanstep =	0,
	.ypanstep =	0,
	.ywrapstep =	0,
	.accel =	FB_ACCEL_NONE,
};

static struct fb_var_screeninfo hecubafb_var __devinitdata = {
	.xres		= DPY_W,
	.yres		= DPY_H,
	.xres_virtual	= DPY_W,
	.yres_virtual	= DPY_H,
	.bits_per_pixel	= 1,
	.nonstd		= 1,
};

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 int hecubafb_enable;
static unsigned int irq;

static DECLARE_WAIT_QUEUE_HEAD(hecubafb_waitq);

static void hcb_set_ctl(struct hecubafb_par *par)
{
	outb(par->ctl, par->cio_addr);
}

static unsigned char hcb_get_ctl(struct hecubafb_par *par)
{
	return inb(par->c2io_addr);
}

static void hcb_set_data(struct hecubafb_par *par, unsigned char value)
{
	outb(value, par->dio_addr);
}

static int __devinit apollo_init_control(struct hecubafb_par *par)
{
	unsigned char ctl;
	/* 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 */
	par->ctl = HCB_NWUP_BIT | HCB_RW_BIT | HCB_NCD_BIT ;
	par->ctl &= ~HCB_NDS_BIT;
	hcb_set_ctl(par);

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

	return 0;
}

void hcb_wait_for_ack(struct hecubafb_par *par)
{

	int timeout;
	unsigned char ctl;

	timeout=500;
	do {
		ctl = hcb_get_ctl(par);
		if ((ctl & HCB_ACK_BIT))
			return;
		udelay(1);
	} while (timeout--);
	printk(KERN_ERR "timed out waiting for ack\n");
}

void hcb_wait_for_ack_clear(struct hecubafb_par *par)
{

	int timeout;
	unsigned char ctl;

	timeout=500;
	do {
		ctl = hcb_get_ctl(par);
		if (!(ctl & HCB_ACK_BIT))
			return;
		udelay(1);
	} while (timeout--);
	printk(KERN_ERR "timed out waiting for clear\n");
}

void apollo_send_data(struct hecubafb_par *par, unsigned char data)
{
	/* set data */
	hcb_set_data(par, data);

	/* set DS low */
	par->ctl |= HCB_NDS_BIT;
	hcb_set_ctl(par);

	hcb_wait_for_ack(par);

	/* set DS hi */
	par->ctl &= ~(HCB_NDS_BIT);
	hcb_set_ctl(par);

	hcb_wait_for_ack_clear(par);
}

void apollo_send_command(struct hecubafb_par *par, unsigned char data)
{
	/* command so set CD to high */
	par->ctl &= ~(HCB_NCD_BIT);
	hcb_set_ctl(par);

	/* actually strobe with command */
	apollo_send_data(par, data);

	/* clear CD back to low */
	par->ctl |= (HCB_NCD_BIT);
	hcb_set_ctl(par);
}

/* main hecubafb functions */

static void hecubafb_dpy_update(struct hecubafb_par *par)
{
	int i;
	unsigned char *buf = par->info->screen_base;

	apollo_send_command(par, 0xA0);

	for (i=0; i < (DPY_W*DPY_H/8); i++) {
		apollo_send_data(par, *(buf++));
	}

	apollo_send_command(par, 0xA1);
	apollo_send_command(par, 0xA2);
}

/* this is called back from the deferred io workqueue */
static void hecubafb_dpy_deferred_io(struct fb_info *info,
				struct list_head *pagelist)
{
	hecubafb_dpy_update(info->par);
}

static void hecubafb_fillrect(struct fb_info *info,
				   const struct fb_fillrect *rect)
{
	struct hecubafb_par *par = info->par;

	cfb_fillrect(info, rect);

	hecubafb_dpy_update(par);
}

static void hecubafb_copyarea(struct fb_info *info,
				   const struct fb_copyarea *area)
{
	struct hecubafb_par *par = info->par;

	cfb_copyarea(info, area);

	hecubafb_dpy_update(par);
}

static void hecubafb_imageblit(struct fb_info *info,
				const struct fb_image *image)
{
	struct hecubafb_par *par = info->par;

	cfb_imageblit(info, image);

	hecubafb_dpy_update(par);
}

/*
 * this is the slow path from userspace. they can seek and write to
 * the fb. it's inefficient to do anything less than a full screen draw
 */
static ssize_t hecubafb_write(struct file *file, const char __user *buf,
				size_t count, loff_t *ppos)
{
	struct inode *inode;
	int fbidx;
	struct fb_info *info;
	unsigned long p;
	int err=-EINVAL;
	struct hecubafb_par *par;
	unsigned int xres;
	unsigned int fbmemlength;

	p = *ppos;
	inode = file->f_dentry->d_inode;
	fbidx = iminor(inode);
	info = registered_fb[fbidx];

	if (!info || !info->screen_base)
		return -ENODEV;

	par = info->par;
	xres = info->var.xres;
	fbmemlength = (xres * info->var.yres)/8;

	if (p > fbmemlength)
		return -ENOSPC;

	err = 0;
	if ((count + p) > fbmemlength) {
		count = fbmemlength - p;
		err = -ENOSPC;
	}

	if (count) {
		char *base_addr;

		base_addr = info->screen_base;
		count -= copy_from_user(base_addr + p, buf, count);
		*ppos += count;
		err = -EFAULT;
	}

	hecubafb_dpy_update(par);

	if (count)
		return count;

	return err;
}

static struct fb_ops hecubafb_ops = {
	.owner		= THIS_MODULE,
	.fb_write	= hecubafb_write,
	.fb_fillrect	= hecubafb_fillrect,
	.fb_copyarea	= hecubafb_copyarea,
	.fb_imageblit	= hecubafb_imageblit,
};

static struct fb_deferred_io hecubafb_defio = {
	.delay		= HZ,
	.deferred_io	= hecubafb_dpy_deferred_io,
};

static int __devinit hecubafb_probe(struct platform_device *dev)
{
	struct fb_info *info;
	int retval = -ENOMEM;
	int videomemorysize;
	unsigned char *videomemory;
	struct hecubafb_par *par;

	videomemorysize = (DPY_W*DPY_H)/8;

	if (!(videomemory = vmalloc(videomemorysize)))
		return retval;

	memset(videomemory, 0, videomemorysize);

	info = framebuffer_alloc(sizeof(struct hecubafb_par), &dev->dev);
	if (!info)
		goto err;

	info->screen_base = (char __iomem *) videomemory;
	info->fbops = &hecubafb_ops;

	info->var = hecubafb_var;
	info->fix = hecubafb_fix;
	info->fix.smem_len = videomemorysize;
	par = info->par;
	par->info = info;

	if (!dio_addr || !cio_addr || !c2io_addr) {
		printk(KERN_WARNING "no IO addresses supplied\n");
		goto err1;
	}
	par->dio_addr = dio_addr;
	par->cio_addr = cio_addr;
	par->c2io_addr = c2io_addr;
	info->flags = FBINFO_FLAG_DEFAULT;

	info->fbdefio = &hecubafb_defio;
	fb_deferred_io_init(info);

	retval = register_framebuffer(info);
	if (retval < 0)
		goto err1;
	platform_set_drvdata(dev, info);

	printk(KERN_INFO
	       "fb%d: Hecuba frame buffer device, using %dK of video memory\n",
	       info->node, videomemorysize >> 10);

	/* this inits the dpy */
	apollo_init_control(par);

	apollo_send_command(par, APOLLO_INIT_DISPLAY);
	apollo_send_data(par, 0x81);

	/* have to wait while display resets */
	udelay(1000);

	/* if we were told to splash the screen, we just clear it */
	if (!nosplash) {
		apollo_send_command(par, APOLLO_ERASE_DISPLAY);
		apollo_send_data(par, splashval);
	}

	return 0;
err1:
	framebuffer_release(info);
err:
	vfree(videomemory);
	return retval;
}

static int __devexit hecubafb_remove(struct platform_device *dev)
{
	struct fb_info *info = platform_get_drvdata(dev);

	if (info) {
		fb_deferred_io_cleanup(info);
		unregister_framebuffer(info);
		vfree(info->screen_base);
		framebuffer_release(info);
	}
	return 0;
}

static struct platform_driver hecubafb_driver = {
	.probe	= hecubafb_probe,
	.remove = hecubafb_remove,
	.driver	= {
		.name	= "hecubafb",
	},
};

static struct platform_device *hecubafb_device;

static int __init hecubafb_init(void)
{
	int ret;

	if (!hecubafb_enable) {
		printk(KERN_ERR "Use hecubafb_enable to enable the device\n");
		return -ENXIO;
	}

	ret = platform_driver_register(&hecubafb_driver);
	if (!ret) {
		hecubafb_device = platform_device_alloc("hecubafb", 0);
		if (hecubafb_device)
			ret = platform_device_add(hecubafb_device);
		else
			ret = -ENOMEM;

		if (ret) {
			platform_device_put(hecubafb_device);
			platform_driver_unregister(&hecubafb_driver);
		}
	}
	return ret;

}

static void __exit hecubafb_exit(void)
{
	platform_device_unregister(hecubafb_device);
	platform_driver_unregister(&hecubafb_driver);
}

module_param(nosplash, uint, 0);
MODULE_PARM_DESC(nosplash, "Disable doing the splash screen");
module_param(hecubafb_enable, uint, 0);
MODULE_PARM_DESC(hecubafb_enable, "Enable communication with Hecuba board");
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_param(irq, uint, 0);
MODULE_PARM_DESC(irq, "IRQ for the Hecuba board");

module_init(hecubafb_init);
module_exit(hecubafb_exit);

MODULE_DESCRIPTION("fbdev driver for Hecuba board");
MODULE_AUTHOR("Jaya Kumar");
MODULE_LICENSE("GPL");