/*
 *  linux/drivers/video/clps711xfb.c
 *
 *  Copyright (C) 2000-2001 Deep Blue Solutions Ltd.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 *  Framebuffer driver for the CLPS7111 and EP7212 processors.
 */
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/fb.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/platform_device.h>

#include <mach/hardware.h>
#include <asm/mach-types.h>
#include <linux/uaccess.h>

struct fb_info  *cfb;

#define CMAP_MAX_SIZE   16

/*
 * LCD AC Prescale.  This comes from the LCD panel manufacturers specifications.
 * This determines how many clocks + 1 of CL1 before the M signal toggles.
 * The number of lines on the display must not be divisible by this number.
 */
static unsigned int lcd_ac_prescale = 13;

/*
 *    Set a single color register. Return != 0 for invalid regno.
 */
static int
clps7111fb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
                     u_int transp, struct fb_info *info)
{
        unsigned int level, mask, shift, pal;

        if (regno >= (1 << info->var.bits_per_pixel))
                return 1;

        /* gray = 0.30*R + 0.58*G + 0.11*B */
        level = (red * 77 + green * 151 + blue * 28) >> 20;

        /*
         * On an LCD, a high value is dark, while a low value is light. 
         * So we invert the level.
         *
         * This isn't true on all machines, so we only do it on EDB7211.
         *  --rmk
         */
        if (machine_is_edb7211()) {
                level = 15 - level;
        }

        shift = 4 * (regno & 7);
        level <<= shift;
        mask  = 15 << shift;
        level &= mask;

        regno = regno < 8 ? PALLSW : PALMSW;

        pal = clps_readl(regno);
        pal = (pal & ~mask) | level;
        clps_writel(pal, regno);

        return 0;
}

/*
 * Validate the purposed mode.
 */     
static int
clps7111fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
        var->transp.msb_right   = 0;
        var->transp.offset      = 0;
        var->transp.length      = 0;
        var->red.msb_right      = 0;
        var->red.offset         = 0;
        var->red.length         = var->bits_per_pixel;
        var->green              = var->red;
        var->blue               = var->red;

        if (var->bits_per_pixel > 4) 
                return -EINVAL;

        return 0;
}

/*
 * Set the hardware state.
 */ 
static int 
clps7111fb_set_par(struct fb_info *info)
{
        unsigned int lcdcon, syscon, pixclock;

        switch (info->var.bits_per_pixel) {
        case 1:
                info->fix.visual = FB_VISUAL_MONO01;
                break;
        case 2:
                info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
                break;
        case 4:
                info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
                break;
        }

        info->fix.line_length = info->var.xres_virtual * info->var.bits_per_pixel / 8;

        lcdcon = (info->var.xres_virtual * info->var.yres_virtual * info->var.bits_per_pixel) / 128 - 1;
        lcdcon |= ((info->var.xres_virtual / 16) - 1) << 13;
        lcdcon |= lcd_ac_prescale << 25;

        /*
         * Calculate pixel prescale value from the pixclock.  This is:
         *  36.864MHz / pixclock_mhz - 1.
         * However, pixclock is in picoseconds, so this ends up being:
         *  36864000 * pixclock_ps / 10^12 - 1
         * and this will overflow the 32-bit math.  We perform this as
         * (9 * 4096000 == 36864000):
         *  pixclock_ps * 9 * (4096000 / 10^12) - 1
         */
        pixclock = 9 * info->var.pixclock / 244140 - 1;
        lcdcon |= pixclock << 19;

        if (info->var.bits_per_pixel == 4)
                lcdcon |= LCDCON_GSMD;
        if (info->var.bits_per_pixel >= 2)
                lcdcon |= LCDCON_GSEN;

        /*
         * LCDCON must only be changed while the LCD is disabled
         */
        syscon = clps_readl(SYSCON1);
        clps_writel(syscon & ~SYSCON1_LCDEN, SYSCON1);
        clps_writel(lcdcon, LCDCON);
        clps_writel(syscon | SYSCON1_LCDEN, SYSCON1);
        return 0;
}

static int clps7111fb_blank(int blank, struct fb_info *info)
{
        /* Enable/Disable LCD controller. */
        if (blank)
                clps_writel(clps_readl(SYSCON1) & ~SYSCON1_LCDEN, SYSCON1);
        else
                clps_writel(clps_readl(SYSCON1) | SYSCON1_LCDEN, SYSCON1);

        return 0;
}

static struct fb_ops clps7111fb_ops = {
        .owner          = THIS_MODULE,
        .fb_check_var   = clps7111fb_check_var,
        .fb_set_par     = clps7111fb_set_par,
        .fb_setcolreg   = clps7111fb_setcolreg,
        .fb_blank       = clps7111fb_blank,
        .fb_fillrect    = cfb_fillrect,
        .fb_copyarea    = cfb_copyarea,
        .fb_imageblit   = cfb_imageblit,
};

static void clps711x_guess_lcd_params(struct fb_info *info)
{
        unsigned int lcdcon, syscon, size;
        unsigned long phys_base = PAGE_OFFSET;
        void *virt_base = (void *)PAGE_OFFSET;

        info->var.xres_virtual   = 640;
        info->var.yres_virtual   = 240;
        info->var.bits_per_pixel = 4;
        info->var.activate       = FB_ACTIVATE_NOW;
        info->var.height         = -1;
        info->var.width          = -1;
        info->var.pixclock       = 93006; /* 10.752MHz pixel clock */

        /*
         * If the LCD controller is already running, decode the values
         * in LCDCON to xres/yres/bpp/pixclock/acprescale
         */
        syscon = clps_readl(SYSCON1);
        if (syscon & SYSCON1_LCDEN) {
                lcdcon = clps_readl(LCDCON);

                /*
                 * Decode GSMD and GSEN bits to bits per pixel
                 */
                switch (lcdcon & (LCDCON_GSMD | LCDCON_GSEN)) {
                case LCDCON_GSMD | LCDCON_GSEN:
                        info->var.bits_per_pixel = 4;
                        break;

                case LCDCON_GSEN:
                        info->var.bits_per_pixel = 2;
                        break;

                default:
                        info->var.bits_per_pixel = 1;
                        break;
                }

                /*
                 * Decode xres/yres
                 */
                info->var.xres_virtual = (((lcdcon >> 13) & 0x3f) + 1) * 16;
                info->var.yres_virtual = (((lcdcon & 0x1fff) + 1) * 128) /
                                          (info->var.xres_virtual *
                                           info->var.bits_per_pixel);

                /*
                 * Calculate pixclock
                 */
                info->var.pixclock = (((lcdcon >> 19) & 0x3f) + 1) * 244140 / 9;

                /*
                 * Grab AC prescale
                 */
                lcd_ac_prescale = (lcdcon >> 25) & 0x1f;
        }

        info->var.xres = info->var.xres_virtual;
        info->var.yres = info->var.yres_virtual;
        info->var.grayscale = info->var.bits_per_pixel > 1;

        size = info->var.xres * info->var.yres * info->var.bits_per_pixel / 8;

        /*
         * Might be worth checking to see if we can use the on-board
         * RAM if size here...
         * CLPS7110 - no on-board SRAM
         * EP7212   - 38400 bytes
         */
        if (size <= 38400) {
                printk(KERN_INFO "CLPS711xFB: could use on-board SRAM?\n");
        }

        if ((syscon & SYSCON1_LCDEN) == 0) {
                /*
                 * The display isn't running.  Ensure that
                 * the display memory is empty.
                 */
                memset(virt_base, 0, size);
        }

        info->screen_base    = virt_base;
        info->fix.smem_start = phys_base;
        info->fix.smem_len   = PAGE_ALIGN(size);
        info->fix.type       = FB_TYPE_PACKED_PIXELS;
}

static int clps711x_fb_probe(struct platform_device *pdev)
{
        int err = -ENOMEM;

        if (fb_get_options("clps711xfb", NULL))
                return -ENODEV;

        cfb = kzalloc(sizeof(*cfb), GFP_KERNEL);
        if (!cfb)
                goto out;

        strcpy(cfb->fix.id, "clps711x");

        cfb->fbops              = &clps7111fb_ops;
        cfb->flags              = FBINFO_DEFAULT;

        clps711x_guess_lcd_params(cfb);

        fb_alloc_cmap(&cfb->cmap, CMAP_MAX_SIZE, 0);

        err = register_framebuffer(cfb);

out:    return err;
}

static int clps711x_fb_remove(struct platform_device *pdev)
{
        unregister_framebuffer(cfb);
        kfree(cfb);

        return 0;
}

static struct platform_driver clps711x_fb_driver = {
        .driver = {
                .name   = "video-clps711x",
        },
        .probe  = clps711x_fb_probe,
        .remove = clps711x_fb_remove,
};
module_platform_driver(clps711x_fb_driver);

MODULE_AUTHOR("Russell King <rmk@arm.linux.org.uk>");
MODULE_DESCRIPTION("CLPS711X framebuffer driver");
MODULE_LICENSE("GPL");