/*
 * 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 const 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 const 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\n",
                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 = {
                .name   = "hecubafb",
        },
};
module_platform_driver(hecubafb_driver);

MODULE_DESCRIPTION("fbdev driver for Hecuba/Apollo controller");
MODULE_AUTHOR("Jaya Kumar");
MODULE_LICENSE("GPL");