/*
 *  linux/drivers/video/sa1100fb.c
 *
 *  Copyright (C) 1999 Eric A. Thomas
 *   Based on acornfb.c Copyright (C) Russell King.
 *
 * 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.
 *
 *              StrongARM 1100 LCD Controller Frame Buffer Driver
 *
 * Please direct your questions and comments on this driver to the following
 * email address:
 *
 *      linux-arm-kernel@lists.arm.linux.org.uk
 *
 * Clean patches should be sent to the ARM Linux Patch System.  Please see the
 * following web page for more information:
 *
 *      https://www.arm.linux.org.uk/developer/patches/info.shtml
 *
 * Thank you.
 *
 * Known problems:
 *      - With the Neponset plugged into an Assabet, LCD powerdown
 *        doesn't work (LCD stays powered up).  Therefore we shouldn't
 *        blank the screen.
 *      - We don't limit the CPU clock rate nor the mode selection
 *        according to the available SDRAM bandwidth.
 *
 * Other notes:
 *      - Linear grayscale palettes and the kernel.
 *        Such code does not belong in the kernel.  The kernel frame buffer
 *        drivers do not expect a linear colourmap, but a colourmap based on
 *        the VT100 standard mapping.
 *
 *        If your _userspace_ requires a linear colourmap, then the setup of
 *        such a colourmap belongs _in userspace_, not in the kernel.  Code
 *        to set the colourmap correctly from user space has been sent to
 *        David Neuer.  It's around 8 lines of C code, plus another 4 to
 *        detect if we are using grayscale.
 *
 *      - The following must never be specified in a panel definition:
 *           LCCR0_LtlEnd, LCCR3_PixClkDiv, LCCR3_VrtSnchL, LCCR3_HorSnchL
 *
 *      - The following should be specified:
 *           either LCCR0_Color or LCCR0_Mono
 *           either LCCR0_Sngl or LCCR0_Dual
 *           either LCCR0_Act or LCCR0_Pas
 *           either LCCR3_OutEnH or LCCD3_OutEnL
 *           either LCCR3_PixRsEdg or LCCR3_PixFlEdg
 *           either LCCR3_ACBsDiv or LCCR3_ACBsCntOff
 *
 * Code Status:
 * 1999/04/01:
 *      - Driver appears to be working for Brutus 320x200x8bpp mode.  Other
 *        resolutions are working, but only the 8bpp mode is supported.
 *        Changes need to be made to the palette encode and decode routines
 *        to support 4 and 16 bpp modes.
 *        Driver is not designed to be a module.  The FrameBuffer is statically
 *        allocated since dynamic allocation of a 300k buffer cannot be
 *        guaranteed.
 *
 * 1999/06/17:
 *      - FrameBuffer memory is now allocated at run-time when the
 *        driver is initialized.
 *
 * 2000/04/10: Nicolas Pitre <nico@fluxnic.net>
 *      - Big cleanup for dynamic selection of machine type at run time.
 *
 * 2000/07/19: Jamey Hicks <jamey@crl.dec.com>
 *      - Support for Bitsy aka Compaq iPAQ H3600 added.
 *
 * 2000/08/07: Tak-Shing Chan <tchan.rd@idthk.com>
 *             Jeff Sutherland <jsutherland@accelent.com>
 *      - Resolved an issue caused by a change made to the Assabet's PLD
 *        earlier this year which broke the framebuffer driver for newer
 *        Phase 4 Assabets.  Some other parameters were changed to optimize
 *        for the Sharp display.
 *
 * 2000/08/09: Kunihiko IMAI <imai@vasara.co.jp>
 *      - XP860 support added
 *
 * 2000/08/19: Mark Huang <mhuang@livetoy.com>
 *      - Allows standard options to be passed on the kernel command line
 *        for most common passive displays.
 *
 * 2000/08/29:
 *      - s/save_flags_cli/local_irq_save/
 *      - remove unneeded extra save_flags_cli in sa1100fb_enable_lcd_controller
 *
 * 2000/10/10: Erik Mouw <J.A.K.Mouw@its.tudelft.nl>
 *      - Updated LART stuff. Fixed some minor bugs.
 *
 * 2000/10/30: Murphy Chen <murphy@mail.dialogue.com.tw>
 *      - Pangolin support added
 *
 * 2000/10/31: Roman Jordan <jor@hoeft-wessel.de>
 *      - Huw Webpanel support added
 *
 * 2000/11/23: Eric Peng <ericpeng@coventive.com>
 *      - Freebird add
 *
 * 2001/02/07: Jamey Hicks <jamey.hicks@compaq.com>
 *             Cliff Brake <cbrake@accelent.com>
 *      - Added PM callback
 *
 * 2001/05/26: <rmk@arm.linux.org.uk>
 *      - Fix 16bpp so that (a) we use the right colours rather than some
 *        totally random colour depending on what was in page 0, and (b)
 *        we don't de-reference a NULL pointer.
 *      - remove duplicated implementation of consistent_alloc()
 *      - convert dma address types to dma_addr_t
 *      - remove unused 'montype' stuff
 *      - remove redundant zero inits of init_var after the initial
 *        memset.
 *      - remove allow_modeset (acornfb idea does not belong here)
 *
 * 2001/05/28: <rmk@arm.linux.org.uk>
 *      - massive cleanup - move machine dependent data into structures
 *      - I've left various #warnings in - if you see one, and know
 *        the hardware concerned, please get in contact with me.
 *
 * 2001/05/31: <rmk@arm.linux.org.uk>
 *      - Fix LCCR1 HSW value, fix all machine type specifications to
 *        keep values in line.  (Please check your machine type specs)
 *
 * 2001/06/10: <rmk@arm.linux.org.uk>
 *      - Fiddle with the LCD controller from task context only; mainly
 *        so that we can run with interrupts on, and sleep.
 *      - Convert #warnings into #errors.  No pain, no gain. ;)
 *
 * 2001/06/14: <rmk@arm.linux.org.uk>
 *      - Make the palette BPS value for 12bpp come out correctly.
 *      - Take notice of "greyscale" on any colour depth.
 *      - Make truecolor visuals use the RGB channel encoding information.
 *
 * 2001/07/02: <rmk@arm.linux.org.uk>
 *      - Fix colourmap problems.
 *
 * 2001/07/13: <abraham@2d3d.co.za>
 *      - Added support for the ICP LCD-Kit01 on LART. This LCD is
 *        manufactured by Prime View, model no V16C6448AB
 *
 * 2001/07/23: <rmk@arm.linux.org.uk>
 *      - Hand merge version from handhelds.org CVS tree.  See patch
 *        notes for 595/1 for more information.
 *      - Drop 12bpp (it's 16bpp with different colour register mappings).
 *      - This hardware can not do direct colour.  Therefore we don't
 *        support it.
 *
 * 2001/07/27: <rmk@arm.linux.org.uk>
 *      - Halve YRES on dual scan LCDs.
 *
 * 2001/08/22: <rmk@arm.linux.org.uk>
 *      - Add b/w iPAQ pixclock value.
 *
 * 2001/10/12: <rmk@arm.linux.org.uk>
 *      - Add patch 681/1 and clean up stork definitions.
 */

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/errno.h>
#include <linux/string.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/fb.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/ioport.h>
#include <linux/cpufreq.h>
#include <linux/gpio/consumer.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/mutex.h>
#include <linux/io.h>
#include <linux/clk.h>

#include <video/sa1100fb.h>

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

/*
 * Complain if VAR is out of range.
 */
#define DEBUG_VAR 1

#include "sa1100fb.h"

static const struct sa1100fb_rgb rgb_4 = {
        .red    = { .offset = 0,  .length = 4, },
        .green  = { .offset = 0,  .length = 4, },
        .blue   = { .offset = 0,  .length = 4, },
        .transp = { .offset = 0,  .length = 0, },
};

static const struct sa1100fb_rgb rgb_8 = {
        .red    = { .offset = 0,  .length = 8, },
        .green  = { .offset = 0,  .length = 8, },
        .blue   = { .offset = 0,  .length = 8, },
        .transp = { .offset = 0,  .length = 0, },
};

static const struct sa1100fb_rgb def_rgb_16 = {
        .red    = { .offset = 11, .length = 5, },
        .green  = { .offset = 5,  .length = 6, },
        .blue   = { .offset = 0,  .length = 5, },
        .transp = { .offset = 0,  .length = 0, },
};



static int sa1100fb_activate_var(struct fb_var_screeninfo *var, struct sa1100fb_info *);
static void set_ctrlr_state(struct sa1100fb_info *fbi, u_int state);

static inline void sa1100fb_schedule_work(struct sa1100fb_info *fbi, u_int state)
{
        unsigned long flags;

        local_irq_save(flags);
        /*
         * We need to handle two requests being made at the same time.
         * There are two important cases:
         *  1. When we are changing VT (C_REENABLE) while unblanking (C_ENABLE)
         *     We must perform the unblanking, which will do our REENABLE for us.
         *  2. When we are blanking, but immediately unblank before we have
         *     blanked.  We do the "REENABLE" thing here as well, just to be sure.
         */
        if (fbi->task_state == C_ENABLE && state == C_REENABLE)
                state = (u_int) -1;
        if (fbi->task_state == C_DISABLE && state == C_ENABLE)
                state = C_REENABLE;

        if (state != (u_int)-1) {
                fbi->task_state = state;
                schedule_work(&fbi->task);
        }
        local_irq_restore(flags);
}

static inline u_int chan_to_field(u_int chan, struct fb_bitfield *bf)
{
        chan &= 0xffff;
        chan >>= 16 - bf->length;
        return chan << bf->offset;
}

/*
 * Convert bits-per-pixel to a hardware palette PBS value.
 */
static inline u_int palette_pbs(struct fb_var_screeninfo *var)
{
        int ret = 0;
        switch (var->bits_per_pixel) {
        case 4:  ret = 0 << 12; break;
        case 8:  ret = 1 << 12; break;
        case 16: ret = 2 << 12; break;
        }
        return ret;
}

static int
sa1100fb_setpalettereg(u_int regno, u_int red, u_int green, u_int blue,
                       u_int trans, struct fb_info *info)
{
        struct sa1100fb_info *fbi =
                container_of(info, struct sa1100fb_info, fb);
        u_int val, ret = 1;

        if (regno < fbi->palette_size) {
                val = ((red >> 4) & 0xf00);
                val |= ((green >> 8) & 0x0f0);
                val |= ((blue >> 12) & 0x00f);

                if (regno == 0)
                        val |= palette_pbs(&fbi->fb.var);

                fbi->palette_cpu[regno] = val;
                ret = 0;
        }
        return ret;
}

static int
sa1100fb_setcolreg(u_int regno, u_int red, u_int green, u_int blue,
                   u_int trans, struct fb_info *info)
{
        struct sa1100fb_info *fbi =
                container_of(info, struct sa1100fb_info, fb);
        unsigned int val;
        int ret = 1;

        /*
         * If inverse mode was selected, invert all the colours
         * rather than the register number.  The register number
         * is what you poke into the framebuffer to produce the
         * colour you requested.
         */
        if (fbi->inf->cmap_inverse) {
                red   = 0xffff - red;
                green = 0xffff - green;
                blue  = 0xffff - blue;
        }

        /*
         * If greyscale is true, then we convert the RGB value
         * to greyscale no mater what visual we are using.
         */
        if (fbi->fb.var.grayscale)
                red = green = blue = (19595 * red + 38470 * green +
                                        7471 * blue) >> 16;

        switch (fbi->fb.fix.visual) {
        case FB_VISUAL_TRUECOLOR:
                /*
                 * 12 or 16-bit True Colour.  We encode the RGB value
                 * according to the RGB bitfield information.
                 */
                if (regno < 16) {
                        val  = chan_to_field(red, &fbi->fb.var.red);
                        val |= chan_to_field(green, &fbi->fb.var.green);
                        val |= chan_to_field(blue, &fbi->fb.var.blue);

                        fbi->pseudo_palette[regno] = val;
                        ret = 0;
                }
                break;

        case FB_VISUAL_STATIC_PSEUDOCOLOR:
        case FB_VISUAL_PSEUDOCOLOR:
                ret = sa1100fb_setpalettereg(regno, red, green, blue, trans, info);
                break;
        }

        return ret;
}

#ifdef CONFIG_CPU_FREQ
/*
 *  sa1100fb_display_dma_period()
 *    Calculate the minimum period (in picoseconds) between two DMA
 *    requests for the LCD controller.  If we hit this, it means we're
 *    doing nothing but LCD DMA.
 */
static inline unsigned int sa1100fb_display_dma_period(struct fb_var_screeninfo *var)
{
        /*
         * Period = pixclock * bits_per_byte * bytes_per_transfer
         *              / memory_bits_per_pixel;
         */
        return var->pixclock * 8 * 16 / var->bits_per_pixel;
}
#endif

/*
 *  sa1100fb_check_var():
 *    Round up in the following order: bits_per_pixel, xres,
 *    yres, xres_virtual, yres_virtual, xoffset, yoffset, grayscale,
 *    bitfields, horizontal timing, vertical timing.
 */
static int
sa1100fb_check_var(struct fb_var_screeninfo *var, struct fb_info *info)
{
        struct sa1100fb_info *fbi =
                container_of(info, struct sa1100fb_info, fb);
        int rgbidx;

        if (var->xres < MIN_XRES)
                var->xres = MIN_XRES;
        if (var->yres < MIN_YRES)
                var->yres = MIN_YRES;
        if (var->xres > fbi->inf->xres)
                var->xres = fbi->inf->xres;
        if (var->yres > fbi->inf->yres)
                var->yres = fbi->inf->yres;
        var->xres_virtual = max(var->xres_virtual, var->xres);
        var->yres_virtual = max(var->yres_virtual, var->yres);

        dev_dbg(fbi->dev, "var->bits_per_pixel=%d\n", var->bits_per_pixel);
        switch (var->bits_per_pixel) {
        case 4:
                rgbidx = RGB_4;
                break;
        case 8:
                rgbidx = RGB_8;
                break;
        case 16:
                rgbidx = RGB_16;
                break;
        default:
                return -EINVAL;
        }

        /*
         * Copy the RGB parameters for this display
         * from the machine specific parameters.
         */
        var->red    = fbi->rgb[rgbidx]->red;
        var->green  = fbi->rgb[rgbidx]->green;
        var->blue   = fbi->rgb[rgbidx]->blue;
        var->transp = fbi->rgb[rgbidx]->transp;

        dev_dbg(fbi->dev, "RGBT length = %d:%d:%d:%d\n",
                var->red.length, var->green.length, var->blue.length,
                var->transp.length);

        dev_dbg(fbi->dev, "RGBT offset = %d:%d:%d:%d\n",
                var->red.offset, var->green.offset, var->blue.offset,
                var->transp.offset);

#ifdef CONFIG_CPU_FREQ
        dev_dbg(fbi->dev, "dma period = %d ps, clock = %ld kHz\n",
                sa1100fb_display_dma_period(var),
                clk_get_rate(fbi->clk) / 1000);
#endif

        return 0;
}

static void sa1100fb_set_visual(struct sa1100fb_info *fbi, u32 visual)
{
        if (fbi->inf->set_visual)
                fbi->inf->set_visual(visual);
}

/*
 * sa1100fb_set_par():
 *      Set the user defined part of the display for the specified console
 */
static int sa1100fb_set_par(struct fb_info *info)
{
        struct sa1100fb_info *fbi =
                container_of(info, struct sa1100fb_info, fb);
        struct fb_var_screeninfo *var = &info->var;
        unsigned long palette_mem_size;

        dev_dbg(fbi->dev, "set_par\n");

        if (var->bits_per_pixel == 16)
                fbi->fb.fix.visual = FB_VISUAL_TRUECOLOR;
        else if (!fbi->inf->cmap_static)
                fbi->fb.fix.visual = FB_VISUAL_PSEUDOCOLOR;
        else {
                /*
                 * Some people have weird ideas about wanting static
                 * pseudocolor maps.  I suspect their user space
                 * applications are broken.
                 */
                fbi->fb.fix.visual = FB_VISUAL_STATIC_PSEUDOCOLOR;
        }

        fbi->fb.fix.line_length = var->xres_virtual *
                                  var->bits_per_pixel / 8;
        fbi->palette_size = var->bits_per_pixel == 8 ? 256 : 16;

        palette_mem_size = fbi->palette_size * sizeof(u16);

        dev_dbg(fbi->dev, "palette_mem_size = 0x%08lx\n", palette_mem_size);

        fbi->palette_cpu = (u16 *)(fbi->map_cpu + PAGE_SIZE - palette_mem_size);
        fbi->palette_dma = fbi->map_dma + PAGE_SIZE - palette_mem_size;

        /*
         * Set (any) board control register to handle new color depth
         */
        sa1100fb_set_visual(fbi, fbi->fb.fix.visual);
        sa1100fb_activate_var(var, fbi);

        return 0;
}

#if 0
static int
sa1100fb_set_cmap(struct fb_cmap *cmap, int kspc, int con,
                  struct fb_info *info)
{
        struct sa1100fb_info *fbi = (struct sa1100fb_info *)info;

        /*
         * Make sure the user isn't doing something stupid.
         */
        if (!kspc && (fbi->fb.var.bits_per_pixel == 16 || fbi->inf->cmap_static))
                return -EINVAL;

        return gen_set_cmap(cmap, kspc, con, info);
}
#endif

/*
 * Formal definition of the VESA spec:
 *  On
 *      This refers to the state of the display when it is in full operation
 *  Stand-By
 *      This defines an optional operating state of minimal power reduction with
 *      the shortest recovery time
 *  Suspend
 *      This refers to a level of power management in which substantial power
 *      reduction is achieved by the display.  The display can have a longer
 *      recovery time from this state than from the Stand-by state
 *  Off
 *      This indicates that the display is consuming the lowest level of power
 *      and is non-operational. Recovery from this state may optionally require
 *      the user to manually power on the monitor
 *
 *  Now, the fbdev driver adds an additional state, (blank), where they
 *  turn off the video (maybe by colormap tricks), but don't mess with the
 *  video itself: think of it semantically between on and Stand-By.
 *
 *  So here's what we should do in our fbdev blank routine:
 *
 *      VESA_NO_BLANKING (mode 0)       Video on,  front/back light on
 *      VESA_VSYNC_SUSPEND (mode 1)     Video on,  front/back light off
 *      VESA_HSYNC_SUSPEND (mode 2)     Video on,  front/back light off
 *      VESA_POWERDOWN (mode 3)         Video off, front/back light off
 *
 *  This will match the matrox implementation.
 */
/*
 * sa1100fb_blank():
 *      Blank the display by setting all palette values to zero.  Note, the
 *      12 and 16 bpp modes don't really use the palette, so this will not
 *      blank the display in all modes.
 */
static int sa1100fb_blank(int blank, struct fb_info *info)
{
        struct sa1100fb_info *fbi =
                container_of(info, struct sa1100fb_info, fb);
        int i;

        dev_dbg(fbi->dev, "sa1100fb_blank: blank=%d\n", blank);

        switch (blank) {
        case FB_BLANK_POWERDOWN:
        case FB_BLANK_VSYNC_SUSPEND:
        case FB_BLANK_HSYNC_SUSPEND:
        case FB_BLANK_NORMAL:
                if (fbi->fb.fix.visual == FB_VISUAL_PSEUDOCOLOR ||
                    fbi->fb.fix.visual == FB_VISUAL_STATIC_PSEUDOCOLOR)
                        for (i = 0; i < fbi->palette_size; i++)
                                sa1100fb_setpalettereg(i, 0, 0, 0, 0, info);
                sa1100fb_schedule_work(fbi, C_DISABLE);
                break;

        case FB_BLANK_UNBLANK:
                if (fbi->fb.fix.visual == FB_VISUAL_PSEUDOCOLOR ||
                    fbi->fb.fix.visual == FB_VISUAL_STATIC_PSEUDOCOLOR)
                        fb_set_cmap(&fbi->fb.cmap, info);
                sa1100fb_schedule_work(fbi, C_ENABLE);
        }
        return 0;
}

static int sa1100fb_mmap(struct fb_info *info,
                         struct vm_area_struct *vma)
{
        struct sa1100fb_info *fbi =
                container_of(info, struct sa1100fb_info, fb);
        unsigned long off = vma->vm_pgoff << PAGE_SHIFT;

        vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);

        if (off < info->fix.smem_len) {
                vma->vm_pgoff += 1; /* skip over the palette */
                return dma_mmap_wc(fbi->dev, vma, fbi->map_cpu, fbi->map_dma,
                                   fbi->map_size);
        }

        vma->vm_page_prot = pgprot_noncached(vma->vm_page_prot);

        return vm_iomap_memory(vma, info->fix.mmio_start, info->fix.mmio_len);
}

static const struct fb_ops sa1100fb_ops = {
        .owner          = THIS_MODULE,
        __FB_DEFAULT_IOMEM_OPS_RDWR,
        .fb_check_var   = sa1100fb_check_var,
        .fb_set_par     = sa1100fb_set_par,
//      .fb_set_cmap    = sa1100fb_set_cmap,
        .fb_setcolreg   = sa1100fb_setcolreg,
        .fb_blank       = sa1100fb_blank,
        __FB_DEFAULT_IOMEM_OPS_DRAW,
        .fb_mmap        = sa1100fb_mmap,
};

/*
 * Calculate the PCD value from the clock rate (in picoseconds).
 * We take account of the PPCR clock setting.
 */
static inline unsigned int get_pcd(struct sa1100fb_info *fbi,
                unsigned int pixclock)
{
        unsigned int pcd = clk_get_rate(fbi->clk) / 100 / 1000;

        pcd *= pixclock;
        pcd /= 10000000;

        return pcd + 1; /* make up for integer math truncations */
}

/*
 * sa1100fb_activate_var():
 *      Configures LCD Controller based on entries in var parameter.  Settings are
 *      only written to the controller if changes were made.
 */
static int sa1100fb_activate_var(struct fb_var_screeninfo *var, struct sa1100fb_info *fbi)
{
        struct sa1100fb_lcd_reg new_regs;
        u_int half_screen_size, yres, pcd;
        u_long flags;

        dev_dbg(fbi->dev, "Configuring SA1100 LCD\n");

        dev_dbg(fbi->dev, "var: xres=%d hslen=%d lm=%d rm=%d\n",
                var->xres, var->hsync_len,
                var->left_margin, var->right_margin);
        dev_dbg(fbi->dev, "var: yres=%d vslen=%d um=%d bm=%d\n",
                var->yres, var->vsync_len,
                var->upper_margin, var->lower_margin);

#if DEBUG_VAR
        if (var->xres < 16        || var->xres > 1024)
                dev_err(fbi->dev, "%s: invalid xres %d\n",
                        fbi->fb.fix.id, var->xres);
        if (var->hsync_len < 1    || var->hsync_len > 64)
                dev_err(fbi->dev, "%s: invalid hsync_len %d\n",
                        fbi->fb.fix.id, var->hsync_len);
        if (var->left_margin < 1  || var->left_margin > 255)
                dev_err(fbi->dev, "%s: invalid left_margin %d\n",
                        fbi->fb.fix.id, var->left_margin);
        if (var->right_margin < 1 || var->right_margin > 255)
                dev_err(fbi->dev, "%s: invalid right_margin %d\n",
                        fbi->fb.fix.id, var->right_margin);
        if (var->yres < 1         || var->yres > 1024)
                dev_err(fbi->dev, "%s: invalid yres %d\n",
                        fbi->fb.fix.id, var->yres);
        if (var->vsync_len < 1    || var->vsync_len > 64)
                dev_err(fbi->dev, "%s: invalid vsync_len %d\n",
                        fbi->fb.fix.id, var->vsync_len);
        if (var->upper_margin < 0 || var->upper_margin > 255)
                dev_err(fbi->dev, "%s: invalid upper_margin %d\n",
                        fbi->fb.fix.id, var->upper_margin);
        if (var->lower_margin < 0 || var->lower_margin > 255)
                dev_err(fbi->dev, "%s: invalid lower_margin %d\n",
                        fbi->fb.fix.id, var->lower_margin);
#endif

        new_regs.lccr0 = fbi->inf->lccr0 |
                LCCR0_LEN | LCCR0_LDM | LCCR0_BAM |
                LCCR0_ERM | LCCR0_LtlEnd | LCCR0_DMADel(0);

        new_regs.lccr1 =
                LCCR1_DisWdth(var->xres) +
                LCCR1_HorSnchWdth(var->hsync_len) +
                LCCR1_BegLnDel(var->left_margin) +
                LCCR1_EndLnDel(var->right_margin);

        /*
         * If we have a dual scan LCD, then we need to halve
         * the YRES parameter.
         */
        yres = var->yres;
        if (fbi->inf->lccr0 & LCCR0_Dual)
                yres /= 2;

        new_regs.lccr2 =
                LCCR2_DisHght(yres) +
                LCCR2_VrtSnchWdth(var->vsync_len) +
                LCCR2_BegFrmDel(var->upper_margin) +
                LCCR2_EndFrmDel(var->lower_margin);

        pcd = get_pcd(fbi, var->pixclock);
        new_regs.lccr3 = LCCR3_PixClkDiv(pcd) | fbi->inf->lccr3 |
                (var->sync & FB_SYNC_HOR_HIGH_ACT ? LCCR3_HorSnchH : LCCR3_HorSnchL) |
                (var->sync & FB_SYNC_VERT_HIGH_ACT ? LCCR3_VrtSnchH : LCCR3_VrtSnchL);

        dev_dbg(fbi->dev, "nlccr0 = 0x%08lx\n", new_regs.lccr0);
        dev_dbg(fbi->dev, "nlccr1 = 0x%08lx\n", new_regs.lccr1);
        dev_dbg(fbi->dev, "nlccr2 = 0x%08lx\n", new_regs.lccr2);
        dev_dbg(fbi->dev, "nlccr3 = 0x%08lx\n", new_regs.lccr3);

        half_screen_size = var->bits_per_pixel;
        half_screen_size = half_screen_size * var->xres * var->yres / 16;

        /* Update shadow copy atomically */
        local_irq_save(flags);
        fbi->dbar1 = fbi->palette_dma;
        fbi->dbar2 = fbi->screen_dma + half_screen_size;

        fbi->reg_lccr0 = new_regs.lccr0;
        fbi->reg_lccr1 = new_regs.lccr1;
        fbi->reg_lccr2 = new_regs.lccr2;
        fbi->reg_lccr3 = new_regs.lccr3;
        local_irq_restore(flags);

        /*
         * Only update the registers if the controller is enabled
         * and something has changed.
         */
        if (readl_relaxed(fbi->base + LCCR0) != fbi->reg_lccr0 ||
            readl_relaxed(fbi->base + LCCR1) != fbi->reg_lccr1 ||
            readl_relaxed(fbi->base + LCCR2) != fbi->reg_lccr2 ||
            readl_relaxed(fbi->base + LCCR3) != fbi->reg_lccr3 ||
            readl_relaxed(fbi->base + DBAR1) != fbi->dbar1 ||
            readl_relaxed(fbi->base + DBAR2) != fbi->dbar2)
                sa1100fb_schedule_work(fbi, C_REENABLE);

        return 0;
}

/*
 * NOTE!  The following functions are purely helpers for set_ctrlr_state.
 * Do not call them directly; set_ctrlr_state does the correct serialisation
 * to ensure that things happen in the right way 100% of time time.
 *      -- rmk
 */
static inline void __sa1100fb_backlight_power(struct sa1100fb_info *fbi, int on)
{
        dev_dbg(fbi->dev, "backlight o%s\n", on ? "n" : "ff");

        if (fbi->inf->backlight_power)
                fbi->inf->backlight_power(on);
}

static inline void __sa1100fb_lcd_power(struct sa1100fb_info *fbi, int on)
{
        dev_dbg(fbi->dev, "LCD power o%s\n", on ? "n" : "ff");

        if (fbi->inf->lcd_power)
                fbi->inf->lcd_power(on);
}

static void sa1100fb_setup_gpio(struct sa1100fb_info *fbi)
{
        u_int mask = 0;

        /*
         * Enable GPIO<9:2> for LCD use if:
         *  1. Active display, or
         *  2. Color Dual Passive display
         *
         * see table 11.8 on page 11-27 in the SA1100 manual
         *   -- Erik.
         *
         * SA1110 spec update nr. 25 says we can and should
         * clear LDD15 to 12 for 4 or 8bpp modes with active
         * panels.
         */
        if ((fbi->reg_lccr0 & LCCR0_CMS) == LCCR0_Color &&
            (fbi->reg_lccr0 & (LCCR0_Dual|LCCR0_Act)) != 0) {
                mask = GPIO_LDD11 | GPIO_LDD10 | GPIO_LDD9  | GPIO_LDD8;

                if (fbi->fb.var.bits_per_pixel > 8 ||
                    (fbi->reg_lccr0 & (LCCR0_Dual|LCCR0_Act)) == LCCR0_Dual)
                        mask |= GPIO_LDD15 | GPIO_LDD14 | GPIO_LDD13 | GPIO_LDD12;

        }

        if (mask) {
                unsigned long flags;

                /*
                 * SA-1100 requires the GPIO direction register set
                 * appropriately for the alternate function.  Hence
                 * we set it here via bitmask rather than excessive
                 * fiddling via the GPIO subsystem - and even then
                 * we'll still have to deal with GAFR.
                 */
                local_irq_save(flags);
                GPDR |= mask;
                GAFR |= mask;
                local_irq_restore(flags);
        }
}

static void sa1100fb_enable_controller(struct sa1100fb_info *fbi)
{
        dev_dbg(fbi->dev, "Enabling LCD controller\n");

        /*
         * Make sure the mode bits are present in the first palette entry
         */
        fbi->palette_cpu[0] &= 0xcfff;
        fbi->palette_cpu[0] |= palette_pbs(&fbi->fb.var);

        /* enable LCD controller clock */
        clk_prepare_enable(fbi->clk);

        /* Sequence from 11.7.10 */
        writel_relaxed(fbi->reg_lccr3, fbi->base + LCCR3);
        writel_relaxed(fbi->reg_lccr2, fbi->base + LCCR2);
        writel_relaxed(fbi->reg_lccr1, fbi->base + LCCR1);
        writel_relaxed(fbi->reg_lccr0 & ~LCCR0_LEN, fbi->base + LCCR0);
        writel_relaxed(fbi->dbar1, fbi->base + DBAR1);
        writel_relaxed(fbi->dbar2, fbi->base + DBAR2);
        writel_relaxed(fbi->reg_lccr0 | LCCR0_LEN, fbi->base + LCCR0);

        if (fbi->shannon_lcden)
                gpiod_set_value(fbi->shannon_lcden, 1);

        dev_dbg(fbi->dev, "DBAR1: 0x%08x\n", readl_relaxed(fbi->base + DBAR1));
        dev_dbg(fbi->dev, "DBAR2: 0x%08x\n", readl_relaxed(fbi->base + DBAR2));
        dev_dbg(fbi->dev, "LCCR0: 0x%08x\n", readl_relaxed(fbi->base + LCCR0));
        dev_dbg(fbi->dev, "LCCR1: 0x%08x\n", readl_relaxed(fbi->base + LCCR1));
        dev_dbg(fbi->dev, "LCCR2: 0x%08x\n", readl_relaxed(fbi->base + LCCR2));
        dev_dbg(fbi->dev, "LCCR3: 0x%08x\n", readl_relaxed(fbi->base + LCCR3));
}

static void sa1100fb_disable_controller(struct sa1100fb_info *fbi)
{
        DECLARE_WAITQUEUE(wait, current);
        u32 lccr0;

        dev_dbg(fbi->dev, "Disabling LCD controller\n");

        if (fbi->shannon_lcden)
                gpiod_set_value(fbi->shannon_lcden, 0);

        set_current_state(TASK_UNINTERRUPTIBLE);
        add_wait_queue(&fbi->ctrlr_wait, &wait);

        /* Clear LCD Status Register */
        writel_relaxed(~0, fbi->base + LCSR);

        lccr0 = readl_relaxed(fbi->base + LCCR0);
        lccr0 &= ~LCCR0_LDM;    /* Enable LCD Disable Done Interrupt */
        writel_relaxed(lccr0, fbi->base + LCCR0);
        lccr0 &= ~LCCR0_LEN;    /* Disable LCD Controller */
        writel_relaxed(lccr0, fbi->base + LCCR0);

        schedule_timeout(20 * HZ / 1000);
        remove_wait_queue(&fbi->ctrlr_wait, &wait);

        /* disable LCD controller clock */
        clk_disable_unprepare(fbi->clk);
}

/*
 *  sa1100fb_handle_irq: Handle 'LCD DONE' interrupts.
 */
static irqreturn_t sa1100fb_handle_irq(int irq, void *dev_id)
{
        struct sa1100fb_info *fbi = dev_id;
        unsigned int lcsr = readl_relaxed(fbi->base + LCSR);

        if (lcsr & LCSR_LDD) {
                u32 lccr0 = readl_relaxed(fbi->base + LCCR0) | LCCR0_LDM;
                writel_relaxed(lccr0, fbi->base + LCCR0);
                wake_up(&fbi->ctrlr_wait);
        }

        writel_relaxed(lcsr, fbi->base + LCSR);
        return IRQ_HANDLED;
}

/*
 * This function must be called from task context only, since it will
 * sleep when disabling the LCD controller, or if we get two contending
 * processes trying to alter state.
 */
static void set_ctrlr_state(struct sa1100fb_info *fbi, u_int state)
{
        u_int old_state;

        mutex_lock(&fbi->ctrlr_lock);

        old_state = fbi->state;

        /*
         * Hack around fbcon initialisation.
         */
        if (old_state == C_STARTUP && state == C_REENABLE)
                state = C_ENABLE;

        switch (state) {
        case C_DISABLE_CLKCHANGE:
                /*
                 * Disable controller for clock change.  If the
                 * controller is already disabled, then do nothing.
                 */
                if (old_state != C_DISABLE && old_state != C_DISABLE_PM) {
                        fbi->state = state;
                        sa1100fb_disable_controller(fbi);
                }
                break;

        case C_DISABLE_PM:
        case C_DISABLE:
                /*
                 * Disable controller
                 */
                if (old_state != C_DISABLE) {
                        fbi->state = state;

                        __sa1100fb_backlight_power(fbi, 0);
                        if (old_state != C_DISABLE_CLKCHANGE)
                                sa1100fb_disable_controller(fbi);
                        __sa1100fb_lcd_power(fbi, 0);
                }
                break;

        case C_ENABLE_CLKCHANGE:
                /*
                 * Enable the controller after clock change.  Only
                 * do this if we were disabled for the clock change.
                 */
                if (old_state == C_DISABLE_CLKCHANGE) {
                        fbi->state = C_ENABLE;
                        sa1100fb_enable_controller(fbi);
                }
                break;

        case C_REENABLE:
                /*
                 * Re-enable the controller only if it was already
                 * enabled.  This is so we reprogram the control
                 * registers.
                 */
                if (old_state == C_ENABLE) {
                        sa1100fb_disable_controller(fbi);
                        sa1100fb_setup_gpio(fbi);
                        sa1100fb_enable_controller(fbi);
                }
                break;

        case C_ENABLE_PM:
                /*
                 * Re-enable the controller after PM.  This is not
                 * perfect - think about the case where we were doing
                 * a clock change, and we suspended half-way through.
                 */
                if (old_state != C_DISABLE_PM)
                        break;
                fallthrough;

        case C_ENABLE:
                /*
                 * Power up the LCD screen, enable controller, and
                 * turn on the backlight.
                 */
                if (old_state != C_ENABLE) {
                        fbi->state = C_ENABLE;
                        sa1100fb_setup_gpio(fbi);
                        __sa1100fb_lcd_power(fbi, 1);
                        sa1100fb_enable_controller(fbi);
                        __sa1100fb_backlight_power(fbi, 1);
                }
                break;
        }
        mutex_unlock(&fbi->ctrlr_lock);
}

/*
 * Our LCD controller task (which is called when we blank or unblank)
 * via keventd.
 */
static void sa1100fb_task(struct work_struct *w)
{
        struct sa1100fb_info *fbi = container_of(w, struct sa1100fb_info, task);
        u_int state = xchg(&fbi->task_state, -1);

        set_ctrlr_state(fbi, state);
}

#ifdef CONFIG_CPU_FREQ
/*
 * CPU clock speed change handler.  We need to adjust the LCD timing
 * parameters when the CPU clock is adjusted by the power management
 * subsystem.
 */
static int
sa1100fb_freq_transition(struct notifier_block *nb, unsigned long val,
                         void *data)
{
        struct sa1100fb_info *fbi = TO_INF(nb, freq_transition);
        u_int pcd;

        switch (val) {
        case CPUFREQ_PRECHANGE:
                set_ctrlr_state(fbi, C_DISABLE_CLKCHANGE);
                break;

        case CPUFREQ_POSTCHANGE:
                pcd = get_pcd(fbi, fbi->fb.var.pixclock);
                fbi->reg_lccr3 = (fbi->reg_lccr3 & ~0xff) | LCCR3_PixClkDiv(pcd);
                set_ctrlr_state(fbi, C_ENABLE_CLKCHANGE);
                break;
        }
        return 0;
}
#endif

#ifdef CONFIG_PM
/*
 * Power management hooks.  Note that we won't be called from IRQ context,
 * unlike the blank functions above, so we may sleep.
 */
static int sa1100fb_suspend(struct platform_device *dev, pm_message_t state)
{
        struct sa1100fb_info *fbi = platform_get_drvdata(dev);

        set_ctrlr_state(fbi, C_DISABLE_PM);
        return 0;
}

static int sa1100fb_resume(struct platform_device *dev)
{
        struct sa1100fb_info *fbi = platform_get_drvdata(dev);

        set_ctrlr_state(fbi, C_ENABLE_PM);
        return 0;
}
#else
#define sa1100fb_suspend        NULL
#define sa1100fb_resume         NULL
#endif

/*
 * sa1100fb_map_video_memory():
 *      Allocates the DRAM memory for the frame buffer.  This buffer is
 *      remapped into a non-cached, non-buffered, memory region to
 *      allow palette and pixel writes to occur without flushing the
 *      cache.  Once this area is remapped, all virtual memory
 *      access to the video memory should occur at the new region.
 */
static int sa1100fb_map_video_memory(struct sa1100fb_info *fbi)
{
        /*
         * We reserve one page for the palette, plus the size
         * of the framebuffer.
         */
        fbi->map_size = PAGE_ALIGN(fbi->fb.fix.smem_len + PAGE_SIZE);
        fbi->map_cpu = dma_alloc_wc(fbi->dev, fbi->map_size, &fbi->map_dma,
                                    GFP_KERNEL);

        if (fbi->map_cpu) {
                fbi->fb.screen_base = fbi->map_cpu + PAGE_SIZE;
                fbi->screen_dma = fbi->map_dma + PAGE_SIZE;
                /*
                 * FIXME: this is actually the wrong thing to place in
                 * smem_start.  But fbdev suffers from the problem that
                 * it needs an API which doesn't exist (in this case,
                 * dma_writecombine_mmap)
                 */
                fbi->fb.fix.smem_start = fbi->screen_dma;
        }

        return fbi->map_cpu ? 0 : -ENOMEM;
}

/* Fake monspecs to fill in fbinfo structure */
static const struct fb_monspecs monspecs = {
        .hfmin  = 30000,
        .hfmax  = 70000,
        .vfmin  = 50,
        .vfmax  = 65,
};


static struct sa1100fb_info *sa1100fb_init_fbinfo(struct device *dev)
{
        struct sa1100fb_mach_info *inf = dev_get_platdata(dev);
        struct sa1100fb_info *fbi;
        unsigned i;

        fbi = devm_kzalloc(dev, sizeof(struct sa1100fb_info), GFP_KERNEL);
        if (!fbi)
                return NULL;

        fbi->dev = dev;

        strcpy(fbi->fb.fix.id, SA1100_NAME);

        fbi->fb.fix.type        = FB_TYPE_PACKED_PIXELS;
        fbi->fb.fix.type_aux    = 0;
        fbi->fb.fix.xpanstep    = 0;
        fbi->fb.fix.ypanstep    = 0;
        fbi->fb.fix.ywrapstep   = 0;
        fbi->fb.fix.accel       = FB_ACCEL_NONE;

        fbi->fb.var.nonstd      = 0;
        fbi->fb.var.activate    = FB_ACTIVATE_NOW;
        fbi->fb.var.height      = -1;
        fbi->fb.var.width       = -1;
        fbi->fb.var.accel_flags = 0;
        fbi->fb.var.vmode       = FB_VMODE_NONINTERLACED;

        fbi->fb.fbops           = &sa1100fb_ops;
        fbi->fb.monspecs        = monspecs;
        fbi->fb.pseudo_palette  = fbi->pseudo_palette;

        fbi->rgb[RGB_4]         = &rgb_4;
        fbi->rgb[RGB_8]         = &rgb_8;
        fbi->rgb[RGB_16]        = &def_rgb_16;

        /*
         * People just don't seem to get this.  We don't support
         * anything but correct entries now, so panic if someone
         * does something stupid.
         */
        if (inf->lccr3 & (LCCR3_VrtSnchL|LCCR3_HorSnchL|0xff) ||
            inf->pixclock == 0)
                panic("sa1100fb error: invalid LCCR3 fields set or zero "
                        "pixclock.");

        fbi->fb.var.xres                = inf->xres;
        fbi->fb.var.xres_virtual        = inf->xres;
        fbi->fb.var.yres                = inf->yres;
        fbi->fb.var.yres_virtual        = inf->yres;
        fbi->fb.var.bits_per_pixel      = inf->bpp;
        fbi->fb.var.pixclock            = inf->pixclock;
        fbi->fb.var.hsync_len           = inf->hsync_len;
        fbi->fb.var.left_margin         = inf->left_margin;
        fbi->fb.var.right_margin        = inf->right_margin;
        fbi->fb.var.vsync_len           = inf->vsync_len;
        fbi->fb.var.upper_margin        = inf->upper_margin;
        fbi->fb.var.lower_margin        = inf->lower_margin;
        fbi->fb.var.sync                = inf->sync;
        fbi->fb.var.grayscale           = inf->cmap_greyscale;
        fbi->state                      = C_STARTUP;
        fbi->task_state                 = (u_char)-1;
        fbi->fb.fix.smem_len            = inf->xres * inf->yres *
                                          inf->bpp / 8;
        fbi->inf                        = inf;

        /* Copy the RGB bitfield overrides */
        for (i = 0; i < NR_RGB; i++)
                if (inf->rgb[i])
                        fbi->rgb[i] = inf->rgb[i];

        init_waitqueue_head(&fbi->ctrlr_wait);
        INIT_WORK(&fbi->task, sa1100fb_task);
        mutex_init(&fbi->ctrlr_lock);

        return fbi;
}

static int sa1100fb_probe(struct platform_device *pdev)
{
        struct sa1100fb_info *fbi;
        int ret, irq;

        if (!dev_get_platdata(&pdev->dev)) {
                dev_err(&pdev->dev, "no platform LCD data\n");
                return -EINVAL;
        }

        irq = platform_get_irq(pdev, 0);
        if (irq < 0)
                return -EINVAL;

        fbi = sa1100fb_init_fbinfo(&pdev->dev);
        if (!fbi)
                return -ENOMEM;

        fbi->base = devm_platform_ioremap_resource(pdev, 0);
        if (IS_ERR(fbi->base))
                return PTR_ERR(fbi->base);

        fbi->clk = devm_clk_get(&pdev->dev, NULL);
        if (IS_ERR(fbi->clk))
                return PTR_ERR(fbi->clk);

        ret = devm_request_irq(&pdev->dev, irq, sa1100fb_handle_irq, 0,
                               "LCD", fbi);
        if (ret) {
                dev_err(&pdev->dev, "request_irq failed: %d\n", ret);
                return ret;
        }

        fbi->shannon_lcden = gpiod_get_optional(&pdev->dev, "shannon-lcden",
                                                GPIOD_OUT_LOW);
        if (IS_ERR(fbi->shannon_lcden))
                return PTR_ERR(fbi->shannon_lcden);

        /* Initialize video memory */
        ret = sa1100fb_map_video_memory(fbi);
        if (ret)
                return ret;

        /*
         * This makes sure that our colour bitfield
         * descriptors are correctly initialised.
         */
        sa1100fb_check_var(&fbi->fb.var, &fbi->fb);

        platform_set_drvdata(pdev, fbi);

        ret = register_framebuffer(&fbi->fb);
        if (ret < 0) {
                dma_free_wc(fbi->dev, fbi->map_size, fbi->map_cpu,
                            fbi->map_dma);
                return ret;
        }

#ifdef CONFIG_CPU_FREQ
        fbi->freq_transition.notifier_call = sa1100fb_freq_transition;
        cpufreq_register_notifier(&fbi->freq_transition, CPUFREQ_TRANSITION_NOTIFIER);
#endif

        /* This driver cannot be unloaded at the moment */
        return 0;
}

static struct platform_driver sa1100fb_driver = {
        .probe          = sa1100fb_probe,
        .suspend        = sa1100fb_suspend,
        .resume         = sa1100fb_resume,
        .driver         = {
                .name   = "sa11x0-fb",
        },
};

static int __init sa1100fb_init(void)
{
        if (fb_get_options("sa1100fb", NULL))
                return -ENODEV;

        return platform_driver_register(&sa1100fb_driver);
}

module_init(sa1100fb_init);
MODULE_DESCRIPTION("StrongARM-1100/1110 framebuffer driver");
MODULE_LICENSE("GPL");