/*
   * linux/drivers/video/hecubafb.c -- FB driver for Hecuba/Apollo 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 architecture.
   * The actual display chip is called Apollo and the interface electronics
   * it needs is called Hecuba.
   *
   * It is intended to be architecture independent. A board specific driver
   * must be used to perform all the physical IO interactions. An example
   * is provided as n411.c
   *
   */
  
  #include <linux/module.h>
  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/string.h>
  #include <linux/mm.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 <linux/uaccess.h>
  
  #include <video/hecubafb.h>
  
  /* Display specific information */
  #define DPY_W 600
  #define DPY_H 800
  
  static struct fb_fix_screeninfo hecubafb_fix = {
  	.id =		"hecubafb",
  	.type =		FB_TYPE_PACKED_PIXELS,
  	.visual =	FB_VISUAL_MONO01,
  	.xpanstep =	0,
  	.ypanstep =	0,
  	.ywrapstep =	0,
  	.line_length =	DPY_W,
  	.accel =	FB_ACCEL_NONE,
  };
  
  static struct fb_var_screeninfo hecubafb_var = {
  	.xres		= DPY_W,
  	.yres		= DPY_H,
  	.xres_virtual	= DPY_W,
  	.yres_virtual	= DPY_H,
  	.bits_per_pixel	= 1,
  	.nonstd		= 1,
  };
  
  /* main hecubafb functions */
  
  static void apollo_send_data(struct hecubafb_par *par, unsigned char data)
  {
  	/* set data */
  	par->board->set_data(par, data);
  
  	/* set DS low */
  	par->board->set_ctl(par, HCB_DS_BIT, 0);
  
  	/* wait for ack */
  	par->board->wait_for_ack(par, 0);
  
  	/* set DS hi */
  	par->board->set_ctl(par, HCB_DS_BIT, 1);
  
  	/* wait for ack to clear */
  	par->board->wait_for_ack(par, 1);
  }
  
  static void apollo_send_command(struct hecubafb_par *par, unsigned char data)
  {
  	/* command so set CD to high */
  	par->board->set_ctl(par, HCB_CD_BIT, 1);
  
  	/* actually strobe with command */
  	apollo_send_data(par, data);
  
  	/* clear CD back to low */
  	par->board->set_ctl(par, HCB_CD_BIT, 0);
  }
  
  static void hecubafb_dpy_update(struct hecubafb_par *par)
  {
  	int i;
  	unsigned char *buf = (unsigned char __force *)par->info->screen_base;
  
  	apollo_send_command(par, APOLLO_START_NEW_IMG);
  
  	for (i=0; i < (DPY_W*DPY_H/8); i++) {
  		apollo_send_data(par, *(buf++));
  	}
  
  	apollo_send_command(par, APOLLO_STOP_IMG_DATA);
  	apollo_send_command(par, APOLLO_DISPLAY_IMG);
  }
  
  /* 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;
  
  	sys_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;
  
  	sys_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;
  
  	sys_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 fb_info *info, const char __user *buf,
  				size_t count, loff_t *ppos)
  {
  	struct hecubafb_par *par = info->par;
  	unsigned long p = *ppos;
  	void *dst;
  	int err = 0;
  	unsigned long total_size;
  
  	if (info->state != FBINFO_STATE_RUNNING)
  		return -EPERM;
  
  	total_size = info->fix.smem_len;
  
  	if (p > total_size)
  		return -EFBIG;
  
  	if (count > total_size) {
  		err = -EFBIG;
  		count = total_size;
  	}
  
  	if (count + p > total_size) {
  		if (!err)
  			err = -ENOSPC;
  
  		count = total_size - p;
  	}
  
  	dst = (void __force *) (info->screen_base + p);
  
  	if (copy_from_user(dst, buf, count))
  		err = -EFAULT;
  
  	if  (!err)
  		*ppos += count;
  
  	hecubafb_dpy_update(par);
  
  	return (err) ? err : count;
  }
  
  static struct fb_ops hecubafb_ops = {
  	.owner		= THIS_MODULE,
  	.fb_read        = fb_sys_read,
  	.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 hecubafb_probe(struct platform_device *dev)
  {
  	struct fb_info *info;
  	struct hecuba_board *board;
  	int retval = -ENOMEM;
  	int videomemorysize;
  	unsigned char *videomemory;
  	struct hecubafb_par *par;
  
  	/* pick up board specific routines */
  	board = dev->dev.platform_data;
  	if (!board)
  		return -EINVAL;
  
  	/* try to count device specific driver, if can't, platform recalls */
  	if (!try_module_get(board->owner))
  		return -ENODEV;
  
  	videomemorysize = (DPY_W*DPY_H)/8;
  
  	videomemory = vzalloc(videomemorysize);
  	if (!videomemory)
  		goto err_videomem_alloc;
  
  	info = framebuffer_alloc(sizeof(struct hecubafb_par), &dev->dev);
  	if (!info)
  		goto err_fballoc;
  
  	info->screen_base = (char __force __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;
  	par->board = board;
  	par->send_command = apollo_send_command;
  	par->send_data = apollo_send_data;
  
  	info->flags = FBINFO_FLAG_DEFAULT | FBINFO_VIRTFB;
  
  	info->fbdefio = &hecubafb_defio;
  	fb_deferred_io_init(info);
  
  	retval = register_framebuffer(info);
  	if (retval < 0)
  		goto err_fbreg;
  	platform_set_drvdata(dev, info);
  
  	fb_info(info, "Hecuba frame buffer device, using %dK of video memory
  ",
  		videomemorysize >> 10);
  
  	/* this inits the dpy */
  	retval = par->board->init(par);
  	if (retval < 0)
  		goto err_fbreg;
  
  	return 0;
  err_fbreg:
  	framebuffer_release(info);
  err_fballoc:
  	vfree(videomemory);
  err_videomem_alloc:
  	module_put(board->owner);
  	return retval;
  }
  
  static int hecubafb_remove(struct platform_device *dev)
  {
  	struct fb_info *info = platform_get_drvdata(dev);
  
  	if (info) {
  		struct hecubafb_par *par = info->par;
  		fb_deferred_io_cleanup(info);
  		unregister_framebuffer(info);
  		vfree((void __force *)info->screen_base);
  		if (par->board->remove)
  			par->board->remove(par);
  		module_put(par->board->owner);
  		framebuffer_release(info);
  	}
  	return 0;
  }
  
  static struct platform_driver hecubafb_driver = {
  	.probe	= hecubafb_probe,
  	.remove = hecubafb_remove,
  	.driver	= {
  		.owner	= THIS_MODULE,
  		.name	= "hecubafb",
  	},
  };
  module_platform_driver(hecubafb_driver);
  
  MODULE_DESCRIPTION("fbdev driver for Hecuba/Apollo controller");
  MODULE_AUTHOR("Jaya Kumar");
  MODULE_LICENSE("GPL");