thinkpad-acpi: untangle ACPI/vendor backlight selection

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / video / s3c-fb.c

/* linux/drivers/video/s3c-fb.c
 *
 * Copyright 2008 Openmoko Inc.
 * Copyright 2008 Simtec Electronics
 *      Ben Dooks <ben@simtec.co.uk>
 *      http://armlinux.simtec.co.uk/
 *
 * Samsung SoC Framebuffer driver
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
*/

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/clk.h>
#include <linux/fb.h>
#include <linux/io.h>

#include <mach/map.h>
#include <mach/regs-fb.h>
#include <plat/fb.h>

/* This driver will export a number of framebuffer interfaces depending
 * on the configuration passed in via the platform data. Each fb instance
 * maps to a hardware window. Currently there is no support for runtime
 * setting of the alpha-blending functions that each window has, so only
 * window 0 is actually useful.
 *
 * Window 0 is treated specially, it is used for the basis of the LCD
 * output timings and as the control for the output power-down state.
*/

/* note, some of the functions that get called are derived from including
 * <mach/regs-fb.h> as they are specific to the architecture that the code
 * is being built for.
*/

#ifdef CONFIG_FB_S3C_DEBUG_REGWRITE
#undef writel
#define writel(v, r) do { \
        printk(KERN_DEBUG "%s: %08x => %p\n", __func__, (unsigned int)v, r); \
        __raw_writel(v, r); } while(0)
#endif /* FB_S3C_DEBUG_REGWRITE */

struct s3c_fb;

/**
 * struct s3c_fb_win - per window private data for each framebuffer.
 * @windata: The platform data supplied for the window configuration.
 * @parent: The hardware that this window is part of.
 * @fbinfo: Pointer pack to the framebuffer info for this window.
 * @palette_buffer: Buffer/cache to hold palette entries.
 * @pseudo_palette: For use in TRUECOLOUR modes for entries 0..15/
 * @index: The window number of this window.
 * @palette: The bitfields for changing r/g/b into a hardware palette entry.
 */
struct s3c_fb_win {
        struct s3c_fb_pd_win    *windata;
        struct s3c_fb           *parent;
        struct fb_info          *fbinfo;
        struct s3c_fb_palette    palette;

        u32                     *palette_buffer;
        u32                      pseudo_palette[16];
        unsigned int             index;
};

/**
 * struct s3c_fb - overall hardware state of the hardware
 * @dev: The device that we bound to, for printing, etc.
 * @regs_res: The resource we claimed for the IO registers.
 * @bus_clk: The clk (hclk) feeding our interface and possibly pixclk.
 * @regs: The mapped hardware registers.
 * @enabled: A bitmask of enabled hardware windows.
 * @pdata: The platform configuration data passed with the device.
 * @windows: The hardware windows that have been claimed.
 */
struct s3c_fb {
        struct device           *dev;
        struct resource         *regs_res;
        struct clk              *bus_clk;
        void __iomem            *regs;

        unsigned char            enabled;

        struct s3c_fb_platdata  *pdata;
        struct s3c_fb_win       *windows[S3C_FB_MAX_WIN];
};

/**
 * s3c_fb_win_has_palette() - determine if a mode has a palette
 * @win: The window number being queried.
 * @bpp: The number of bits per pixel to test.
 *
 * Work out if the given window supports palletised data at the specified bpp.
 */
static int s3c_fb_win_has_palette(unsigned int win, unsigned int bpp)
{
        return s3c_fb_win_pal_size(win) <= (1 << bpp);
}

/**
 * s3c_fb_check_var() - framebuffer layer request to verify a given mode.
 * @var: The screen information to verify.
 * @info: The framebuffer device.
 *
 * Framebuffer layer call to verify the given information and allow us to
 * update various information depending on the hardware capabilities.
 */
static int s3c_fb_check_var(struct fb_var_screeninfo *var,
                            struct fb_info *info)
{
        struct s3c_fb_win *win = info->par;
        struct s3c_fb_pd_win *windata = win->windata;
        struct s3c_fb *sfb = win->parent;

        dev_dbg(sfb->dev, "checking parameters\n");

        var->xres_virtual = max((unsigned int)windata->virtual_x, var->xres);
        var->yres_virtual = max((unsigned int)windata->virtual_y, var->yres);

        if (!s3c_fb_validate_win_bpp(win->index, var->bits_per_pixel)) {
                dev_dbg(sfb->dev, "win %d: unsupported bpp %d\n",
                        win->index, var->bits_per_pixel);
                return -EINVAL;
        }

        /* always ensure these are zero, for drop through cases below */
        var->transp.offset = 0;
        var->transp.length = 0;

        switch (var->bits_per_pixel) {
        case 1:
        case 2:
        case 4:
        case 8:
                if (!s3c_fb_win_has_palette(win->index, var->bits_per_pixel)) {
                        /* non palletised, A:1,R:2,G:3,B:2 mode */
                        var->red.offset         = 4;
                        var->green.offset       = 2;
                        var->blue.offset        = 0;
                        var->red.length         = 5;
                        var->green.length       = 3;
                        var->blue.length        = 2;
                        var->transp.offset      = 7;
                        var->transp.length      = 1;
                } else {
                        var->red.offset = 0;
                        var->red.length = var->bits_per_pixel;
                        var->green      = var->red;
                        var->blue       = var->red;
                }
                break;

        case 19:
                /* 666 with one bit alpha/transparency */
                var->transp.offset      = 18;
                var->transp.length      = 1;
        case 18:
                var->bits_per_pixel     = 32;

                /* 666 format */
                var->red.offset         = 12;
                var->green.offset       = 6;
                var->blue.offset        = 0;
                var->red.length         = 6;
                var->green.length       = 6;
                var->blue.length        = 6;
                break;

        case 16:
                /* 16 bpp, 565 format */
                var->red.offset         = 11;
                var->green.offset       = 5;
                var->blue.offset        = 0;
                var->red.length         = 5;
                var->green.length       = 6;
                var->blue.length        = 5;
                break;

        case 28:
        case 25:
                var->transp.length      = var->bits_per_pixel - 24;
                var->transp.offset      = 24;
                /* drop through */
        case 24:
                /* our 24bpp is unpacked, so 32bpp */
                var->bits_per_pixel     = 32;
        case 32:
                var->red.offset         = 16;
                var->red.length         = 8;
                var->green.offset       = 8;
                var->green.length       = 8;
                var->blue.offset        = 0;
                var->blue.length        = 8;
                break;

        default:
                dev_err(sfb->dev, "invalid bpp\n");
        }

        dev_dbg(sfb->dev, "%s: verified parameters\n", __func__);
        return 0;
}

/**
 * s3c_fb_calc_pixclk() - calculate the divider to create the pixel clock.
 * @sfb: The hardware state.
 * @pixclock: The pixel clock wanted, in picoseconds.
 *
 * Given the specified pixel clock, work out the necessary divider to get
 * close to the output frequency.
 */
static int s3c_fb_calc_pixclk(struct s3c_fb *sfb, unsigned int pixclk)
{
        unsigned long clk = clk_get_rate(sfb->bus_clk);
        unsigned long long tmp;
        unsigned int result;

        tmp = (unsigned long long)clk;
        tmp *= pixclk;

        do_div(tmp, 1000000000UL);
        result = (unsigned int)tmp / 1000;

        dev_dbg(sfb->dev, "pixclk=%u, clk=%lu, div=%d (%lu)\n",
                pixclk, clk, result, clk / result);

        return result;
}

/**
 * s3c_fb_align_word() - align pixel count to word boundary
 * @bpp: The number of bits per pixel
 * @pix: The value to be aligned.
 *
 * Align the given pixel count so that it will start on an 32bit word
 * boundary.
 */
static int s3c_fb_align_word(unsigned int bpp, unsigned int pix)
{
        int pix_per_word;

        if (bpp > 16)
                return pix;

        pix_per_word = (8 * 32) / bpp;
        return ALIGN(pix, pix_per_word);
}

/**
 * s3c_fb_set_par() - framebuffer request to set new framebuffer state.
 * @info: The framebuffer to change.
 *
 * Framebuffer layer request to set a new mode for the specified framebuffer
 */
static int s3c_fb_set_par(struct fb_info *info)
{
        struct fb_var_screeninfo *var = &info->var;
        struct s3c_fb_win *win = info->par;
        struct s3c_fb *sfb = win->parent;
        void __iomem *regs = sfb->regs;
        int win_no = win->index;
        u32 osdc_data = 0;
        u32 data;
        u32 pagewidth;
        int clkdiv;

        dev_dbg(sfb->dev, "setting framebuffer parameters\n");

        switch (var->bits_per_pixel) {
        case 32:
        case 24:
        case 16:
        case 12:
                info->fix.visual = FB_VISUAL_TRUECOLOR;
                break;
        case 8:
                if (s3c_fb_win_has_palette(win_no, 8))
                        info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
                else
                        info->fix.visual = FB_VISUAL_TRUECOLOR;
                break;
        case 1:
                info->fix.visual = FB_VISUAL_MONO01;
                break;
        default:
                info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
                break;
        }

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

        /* disable the window whilst we update it */
        writel(0, regs + WINCON(win_no));

        /* use window 0 as the basis for the lcd output timings */

        if (win_no == 0) {
                clkdiv = s3c_fb_calc_pixclk(sfb, var->pixclock);

                data = sfb->pdata->vidcon0;
                data &= ~(VIDCON0_CLKVAL_F_MASK | VIDCON0_CLKDIR);

                if (clkdiv > 1)
                        data |= VIDCON0_CLKVAL_F(clkdiv-1) | VIDCON0_CLKDIR;
                else
                        data &= ~VIDCON0_CLKDIR;        /* 1:1 clock */

                /* write the timing data to the panel */

                data |= VIDCON0_ENVID | VIDCON0_ENVID_F;
                writel(data, regs + VIDCON0);

                data = VIDTCON0_VBPD(var->upper_margin - 1) |
                       VIDTCON0_VFPD(var->lower_margin - 1) |
                       VIDTCON0_VSPW(var->vsync_len - 1);

                writel(data, regs + VIDTCON0);

                data = VIDTCON1_HBPD(var->left_margin - 1) |
                       VIDTCON1_HFPD(var->right_margin - 1) |
                       VIDTCON1_HSPW(var->hsync_len - 1);

                writel(data, regs + VIDTCON1);

                data = VIDTCON2_LINEVAL(var->yres - 1) |
                       VIDTCON2_HOZVAL(var->xres - 1);
                writel(data, regs + VIDTCON2);
        }

        /* write the buffer address */

        writel(info->fix.smem_start, regs + VIDW_BUF_START(win_no));

        data = info->fix.smem_start + info->fix.line_length * var->yres;
        writel(data, regs + VIDW_BUF_END(win_no));

        pagewidth = (var->xres * var->bits_per_pixel) >> 3;
        data = VIDW_BUF_SIZE_OFFSET(info->fix.line_length - pagewidth) |
               VIDW_BUF_SIZE_PAGEWIDTH(pagewidth);
        writel(data, regs + VIDW_BUF_SIZE(win_no));

        /* write 'OSD' registers to control position of framebuffer */

        data = VIDOSDxA_TOPLEFT_X(0) | VIDOSDxA_TOPLEFT_Y(0);
        writel(data, regs + VIDOSD_A(win_no));

        data = VIDOSDxB_BOTRIGHT_X(s3c_fb_align_word(var->bits_per_pixel,
                                                     var->xres - 1)) |
               VIDOSDxB_BOTRIGHT_Y(var->yres - 1);

        writel(data, regs + VIDOSD_B(win_no));

        data = var->xres * var->yres;

        osdc_data = VIDISD14C_ALPHA1_R(0xf) |
                VIDISD14C_ALPHA1_G(0xf) |
                VIDISD14C_ALPHA1_B(0xf);

        if (s3c_fb_has_osd_d(win_no)) {
                writel(data, regs + VIDOSD_D(win_no));
                writel(osdc_data, regs + VIDOSD_C(win_no));
        } else
                writel(data, regs + VIDOSD_C(win_no));

        data = WINCONx_ENWIN;

        /* note, since we have to round up the bits-per-pixel, we end up
         * relying on the bitfield information for r/g/b/a to work out
         * exactly which mode of operation is intended. */

        switch (var->bits_per_pixel) {
        case 1:
                data |= WINCON0_BPPMODE_1BPP;
                data |= WINCONx_BITSWP;
                data |= WINCONx_BURSTLEN_4WORD;
                break;
        case 2:
                data |= WINCON0_BPPMODE_2BPP;
                data |= WINCONx_BITSWP;
                data |= WINCONx_BURSTLEN_8WORD;
                break;
        case 4:
                data |= WINCON0_BPPMODE_4BPP;
                data |= WINCONx_BITSWP;
                data |= WINCONx_BURSTLEN_8WORD;
                break;
        case 8:
                if (var->transp.length != 0)
                        data |= WINCON1_BPPMODE_8BPP_1232;
                else
                        data |= WINCON0_BPPMODE_8BPP_PALETTE;
                data |= WINCONx_BURSTLEN_8WORD;
                data |= WINCONx_BYTSWP;
                break;
        case 16:
                if (var->transp.length != 0)
                        data |= WINCON1_BPPMODE_16BPP_A1555;
                else
                        data |= WINCON0_BPPMODE_16BPP_565;
                data |= WINCONx_HAWSWP;
                data |= WINCONx_BURSTLEN_16WORD;
                break;
        case 24:
        case 32:
                if (var->red.length == 6) {
                        if (var->transp.length != 0)
                                data |= WINCON1_BPPMODE_19BPP_A1666;
                        else
                                data |= WINCON1_BPPMODE_18BPP_666;
                } else if (var->transp.length == 1)
                        data |= WINCON1_BPPMODE_25BPP_A1888
                                | WINCON1_BLD_PIX;
                else if (var->transp.length == 4)
                        data |= WINCON1_BPPMODE_28BPP_A4888
                                | WINCON1_BLD_PIX | WINCON1_ALPHA_SEL;
                else
                        data |= WINCON0_BPPMODE_24BPP_888;

                data |= WINCONx_BURSTLEN_16WORD;
                break;
        }

        /* It has no color key control register for window0 */
        if (win_no > 0) {
                u32 keycon0_data = 0, keycon1_data = 0;

                keycon0_data = ~(WxKEYCON0_KEYBL_EN |
                                WxKEYCON0_KEYEN_F |
                                WxKEYCON0_DIRCON) | WxKEYCON0_COMPKEY(0);

                keycon1_data = WxKEYCON1_COLVAL(0xffffff);

                writel(keycon0_data, regs + WxKEYCONy(win_no-1, 0));
                writel(keycon1_data, regs + WxKEYCONy(win_no-1, 1));
        }

        writel(data, regs + WINCON(win_no));
        writel(0x0, regs + WINxMAP(win_no));

        return 0;
}

/**
 * s3c_fb_update_palette() - set or schedule a palette update.
 * @sfb: The hardware information.
 * @win: The window being updated.
 * @reg: The palette index being changed.
 * @value: The computed palette value.
 *
 * Change the value of a palette register, either by directly writing to
 * the palette (this requires the palette RAM to be disconnected from the
 * hardware whilst this is in progress) or schedule the update for later.
 *
 * At the moment, since we have no VSYNC interrupt support, we simply set
 * the palette entry directly.
 */
static void s3c_fb_update_palette(struct s3c_fb *sfb,
                                  struct s3c_fb_win *win,
                                  unsigned int reg,
                                  u32 value)
{
        void __iomem *palreg;
        u32 palcon;

        palreg = sfb->regs + s3c_fb_pal_reg(win->index, reg);

        dev_dbg(sfb->dev, "%s: win %d, reg %d (%p): %08x\n",
                __func__, win->index, reg, palreg, value);

        win->palette_buffer[reg] = value;

        palcon = readl(sfb->regs + WPALCON);
        writel(palcon | WPALCON_PAL_UPDATE, sfb->regs + WPALCON);

        if (s3c_fb_pal_is16(win->index))
                writew(value, palreg);
        else
                writel(value, palreg);

        writel(palcon, sfb->regs + WPALCON);
}

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

/**
 * s3c_fb_setcolreg() - framebuffer layer request to change palette.
 * @regno: The palette index to change.
 * @red: The red field for the palette data.
 * @green: The green field for the palette data.
 * @blue: The blue field for the palette data.
 * @trans: The transparency (alpha) field for the palette data.
 * @info: The framebuffer being changed.
 */
static int s3c_fb_setcolreg(unsigned regno,
                            unsigned red, unsigned green, unsigned blue,
                            unsigned transp, struct fb_info *info)
{
        struct s3c_fb_win *win = info->par;
        struct s3c_fb *sfb = win->parent;
        unsigned int val;

        dev_dbg(sfb->dev, "%s: win %d: %d => rgb=%d/%d/%d\n",
                __func__, win->index, regno, red, green, blue);

        switch (info->fix.visual) {
        case FB_VISUAL_TRUECOLOR:
                /* true-colour, use pseudo-palette */

                if (regno < 16) {
                        u32 *pal = info->pseudo_palette;

                        val  = chan_to_field(red,   &info->var.red);
                        val |= chan_to_field(green, &info->var.green);
                        val |= chan_to_field(blue,  &info->var.blue);

                        pal[regno] = val;
                }
                break;

        case FB_VISUAL_PSEUDOCOLOR:
                if (regno < s3c_fb_win_pal_size(win->index)) {
                        val  = chan_to_field(red, &win->palette.r);
                        val |= chan_to_field(green, &win->palette.g);
                        val |= chan_to_field(blue, &win->palette.b);

                        s3c_fb_update_palette(sfb, win, regno, val);
                }

                break;

        default:
                return 1;       /* unknown type */
        }

        return 0;
}

/**
 * s3c_fb_enable() - Set the state of the main LCD output
 * @sfb: The main framebuffer state.
 * @enable: The state to set.
 */
static void s3c_fb_enable(struct s3c_fb *sfb, int enable)
{
        u32 vidcon0 = readl(sfb->regs + VIDCON0);

        if (enable)
                vidcon0 |= VIDCON0_ENVID | VIDCON0_ENVID_F;
        else {
                /* see the note in the framebuffer datasheet about
                 * why you cannot take both of these bits down at the
                 * same time. */

                if (!(vidcon0 & VIDCON0_ENVID))
                        return;

                vidcon0 |= VIDCON0_ENVID;
                vidcon0 &= ~VIDCON0_ENVID_F;
        }

        writel(vidcon0, sfb->regs + VIDCON0);
}

/**
 * s3c_fb_blank() - blank or unblank the given window
 * @blank_mode: The blank state from FB_BLANK_*
 * @info: The framebuffer to blank.
 *
 * Framebuffer layer request to change the power state.
 */
static int s3c_fb_blank(int blank_mode, struct fb_info *info)
{
        struct s3c_fb_win *win = info->par;
        struct s3c_fb *sfb = win->parent;
        unsigned int index = win->index;
        u32 wincon;

        dev_dbg(sfb->dev, "blank mode %d\n", blank_mode);

        wincon = readl(sfb->regs + WINCON(index));

        switch (blank_mode) {
        case FB_BLANK_POWERDOWN:
                wincon &= ~WINCONx_ENWIN;
                sfb->enabled &= ~(1 << index);
                /* fall through to FB_BLANK_NORMAL */

        case FB_BLANK_NORMAL:
                /* disable the DMA and display 0x0 (black) */
                writel(WINxMAP_MAP | WINxMAP_MAP_COLOUR(0x0),
                       sfb->regs + WINxMAP(index));
                break;

        case FB_BLANK_UNBLANK:
                writel(0x0, sfb->regs + WINxMAP(index));
                wincon |= WINCONx_ENWIN;
                sfb->enabled |= (1 << index);
                break;

        case FB_BLANK_VSYNC_SUSPEND:
        case FB_BLANK_HSYNC_SUSPEND:
        default:
                return 1;
        }

        writel(wincon, sfb->regs + WINCON(index));

        /* Check the enabled state to see if we need to be running the
         * main LCD interface, as if there are no active windows then
         * it is highly likely that we also do not need to output
         * anything.
         */

        /* We could do something like the following code, but the current
         * system of using framebuffer events means that we cannot make
         * the distinction between just window 0 being inactive and all
         * the windows being down.
         *
         * s3c_fb_enable(sfb, sfb->enabled ? 1 : 0);
        */

        /* we're stuck with this until we can do something about overriding
         * the power control using the blanking event for a single fb.
         */
        if (index == 0)
                s3c_fb_enable(sfb, blank_mode != FB_BLANK_POWERDOWN ? 1 : 0);

        return 0;
}

static struct fb_ops s3c_fb_ops = {
        .owner          = THIS_MODULE,
        .fb_check_var   = s3c_fb_check_var,
        .fb_set_par     = s3c_fb_set_par,
        .fb_blank       = s3c_fb_blank,
        .fb_setcolreg   = s3c_fb_setcolreg,
        .fb_fillrect    = cfb_fillrect,
        .fb_copyarea    = cfb_copyarea,
        .fb_imageblit   = cfb_imageblit,
};

/**
 * s3c_fb_alloc_memory() - allocate display memory for framebuffer window
 * @sfb: The base resources for the hardware.
 * @win: The window to initialise memory for.
 *
 * Allocate memory for the given framebuffer.
 */
static int __devinit s3c_fb_alloc_memory(struct s3c_fb *sfb,
                                         struct s3c_fb_win *win)
{
        struct s3c_fb_pd_win *windata = win->windata;
        unsigned int real_size, virt_size, size;
        struct fb_info *fbi = win->fbinfo;
        dma_addr_t map_dma;

        dev_dbg(sfb->dev, "allocating memory for display\n");

        real_size = windata->win_mode.xres * windata->win_mode.yres;
        virt_size = windata->virtual_x * windata->virtual_y;

        dev_dbg(sfb->dev, "real_size=%u (%u.%u), virt_size=%u (%u.%u)\n",
                real_size, windata->win_mode.xres, windata->win_mode.yres,
                virt_size, windata->virtual_x, windata->virtual_y);

        size = (real_size > virt_size) ? real_size : virt_size;
        size *= (windata->max_bpp > 16) ? 32 : windata->max_bpp;
        size /= 8;

        fbi->fix.smem_len = size;
        size = PAGE_ALIGN(size);

        dev_dbg(sfb->dev, "want %u bytes for window\n", size);

        fbi->screen_base = dma_alloc_writecombine(sfb->dev, size,
                                                  &map_dma, GFP_KERNEL);
        if (!fbi->screen_base)
                return -ENOMEM;

        dev_dbg(sfb->dev, "mapped %x to %p\n",
                (unsigned int)map_dma, fbi->screen_base);

        memset(fbi->screen_base, 0x0, size);
        fbi->fix.smem_start = map_dma;

        return 0;
}

/**
 * s3c_fb_free_memory() - free the display memory for the given window
 * @sfb: The base resources for the hardware.
 * @win: The window to free the display memory for.
 *
 * Free the display memory allocated by s3c_fb_alloc_memory().
 */
static void s3c_fb_free_memory(struct s3c_fb *sfb, struct s3c_fb_win *win)
{
        struct fb_info *fbi = win->fbinfo;

        dma_free_writecombine(sfb->dev, PAGE_ALIGN(fbi->fix.smem_len),
                              fbi->screen_base, fbi->fix.smem_start);
}

/**
 * s3c_fb_release_win() - release resources for a framebuffer window.
 * @win: The window to cleanup the resources for.
 *
 * Release the resources that where claimed for the hardware window,
 * such as the framebuffer instance and any memory claimed for it.
 */
static void s3c_fb_release_win(struct s3c_fb *sfb, struct s3c_fb_win *win)
{
        if (win->fbinfo) {
                unregister_framebuffer(win->fbinfo);
                fb_dealloc_cmap(&win->fbinfo->cmap);
                s3c_fb_free_memory(sfb, win);
                framebuffer_release(win->fbinfo);
        }
}

/**
 * s3c_fb_probe_win() - register an hardware window
 * @sfb: The base resources for the hardware
 * @res: Pointer to where to place the resultant window.
 *
 * Allocate and do the basic initialisation for one of the hardware's graphics
 * windows.
 */
static int __devinit s3c_fb_probe_win(struct s3c_fb *sfb, unsigned int win_no,
                                      struct s3c_fb_win **res)
{
        struct fb_var_screeninfo *var;
        struct fb_videomode *initmode;
        struct s3c_fb_pd_win *windata;
        struct s3c_fb_win *win;
        struct fb_info *fbinfo;
        int palette_size;
        int ret;

        dev_dbg(sfb->dev, "probing window %d\n", win_no);

        palette_size = s3c_fb_win_pal_size(win_no);

        fbinfo = framebuffer_alloc(sizeof(struct s3c_fb_win) +
                                   palette_size * sizeof(u32), sfb->dev);
        if (!fbinfo) {
                dev_err(sfb->dev, "failed to allocate framebuffer\n");
                return -ENOENT;
        }

        windata = sfb->pdata->win[win_no];
        initmode = &windata->win_mode;

        WARN_ON(windata->max_bpp == 0);
        WARN_ON(windata->win_mode.xres == 0);
        WARN_ON(windata->win_mode.yres == 0);

        win = fbinfo->par;
        var = &fbinfo->var;
        win->fbinfo = fbinfo;
        win->parent = sfb;
        win->windata = windata;
        win->index = win_no;
        win->palette_buffer = (u32 *)(win + 1);

        ret = s3c_fb_alloc_memory(sfb, win);
        if (ret) {
                dev_err(sfb->dev, "failed to allocate display memory\n");
                return ret;
        }

        /* setup the r/b/g positions for the window's palette */
        s3c_fb_init_palette(win_no, &win->palette);

        /* setup the initial video mode from the window */
        fb_videomode_to_var(&fbinfo->var, initmode);

        fbinfo->fix.type        = FB_TYPE_PACKED_PIXELS;
        fbinfo->fix.accel       = FB_ACCEL_NONE;
        fbinfo->var.activate    = FB_ACTIVATE_NOW;
        fbinfo->var.vmode       = FB_VMODE_NONINTERLACED;
        fbinfo->var.bits_per_pixel = windata->default_bpp;
        fbinfo->fbops           = &s3c_fb_ops;
        fbinfo->flags           = FBINFO_FLAG_DEFAULT;
        fbinfo->pseudo_palette  = &win->pseudo_palette;

        /* prepare to actually start the framebuffer */

        ret = s3c_fb_check_var(&fbinfo->var, fbinfo);
        if (ret < 0) {
                dev_err(sfb->dev, "check_var failed on initial video params\n");
                return ret;
        }

        /* create initial colour map */

        ret = fb_alloc_cmap(&fbinfo->cmap, s3c_fb_win_pal_size(win_no), 1);
        if (ret == 0)
                fb_set_cmap(&fbinfo->cmap, fbinfo);
        else
                dev_err(sfb->dev, "failed to allocate fb cmap\n");

        s3c_fb_set_par(fbinfo);

        dev_dbg(sfb->dev, "about to register framebuffer\n");

        /* run the check_var and set_par on our configuration. */

        ret = register_framebuffer(fbinfo);
        if (ret < 0) {
                dev_err(sfb->dev, "failed to register framebuffer\n");
                return ret;
        }

        *res = win;
        dev_info(sfb->dev, "window %d: fb %s\n", win_no, fbinfo->fix.id);

        return 0;
}

/**
 * s3c_fb_clear_win() - clear hardware window registers.
 * @sfb: The base resources for the hardware.
 * @win: The window to process.
 *
 * Reset the specific window registers to a known state.
 */
static void s3c_fb_clear_win(struct s3c_fb *sfb, int win)
{
        void __iomem *regs = sfb->regs;

        writel(0, regs + WINCON(win));
        writel(0xffffff, regs + WxKEYCONy(win, 0));
        writel(0xffffff, regs + WxKEYCONy(win, 1));

        writel(0, regs + VIDOSD_A(win));
        writel(0, regs + VIDOSD_B(win));
        writel(0, regs + VIDOSD_C(win));
}

static int __devinit s3c_fb_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct s3c_fb_platdata *pd;
        struct s3c_fb *sfb;
        struct resource *res;
        int win;
        int ret = 0;

        pd = pdev->dev.platform_data;
        if (!pd) {
                dev_err(dev, "no platform data specified\n");
                return -EINVAL;
        }

        sfb = kzalloc(sizeof(struct s3c_fb), GFP_KERNEL);
        if (!sfb) {
                dev_err(dev, "no memory for framebuffers\n");
                return -ENOMEM;
        }

        sfb->dev = dev;
        sfb->pdata = pd;

        sfb->bus_clk = clk_get(dev, "lcd");
        if (IS_ERR(sfb->bus_clk)) {
                dev_err(dev, "failed to get bus clock\n");
                goto err_sfb;
        }

        clk_enable(sfb->bus_clk);

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                dev_err(dev, "failed to find registers\n");
                ret = -ENOENT;
                goto err_clk;
        }

        sfb->regs_res = request_mem_region(res->start, resource_size(res),
                                           dev_name(dev));
        if (!sfb->regs_res) {
                dev_err(dev, "failed to claim register region\n");
                ret = -ENOENT;
                goto err_clk;
        }

        sfb->regs = ioremap(res->start, resource_size(res));
        if (!sfb->regs) {
                dev_err(dev, "failed to map registers\n");
                ret = -ENXIO;
                goto err_req_region;
        }

        dev_dbg(dev, "got resources (regs %p), probing windows\n", sfb->regs);

        /* setup gpio and output polarity controls */

        pd->setup_gpio();

        writel(pd->vidcon1, sfb->regs + VIDCON1);

        /* zero all windows before we do anything */

        for (win = 0; win < S3C_FB_MAX_WIN; win++)
                s3c_fb_clear_win(sfb, win);

        /* we have the register setup, start allocating framebuffers */

        for (win = 0; win < S3C_FB_MAX_WIN; win++) {
                if (!pd->win[win])
                        continue;

                ret = s3c_fb_probe_win(sfb, win, &sfb->windows[win]);
                if (ret < 0) {
                        dev_err(dev, "failed to create window %d\n", win);
                        for (; win >= 0; win--)
                                s3c_fb_release_win(sfb, sfb->windows[win]);
                        goto err_ioremap;
                }
        }

        platform_set_drvdata(pdev, sfb);

        return 0;

err_ioremap:
        iounmap(sfb->regs);

err_req_region:
        release_resource(sfb->regs_res);
        kfree(sfb->regs_res);

err_clk:
        clk_disable(sfb->bus_clk);
        clk_put(sfb->bus_clk);

err_sfb:
        kfree(sfb);
        return ret;
}

/**
 * s3c_fb_remove() - Cleanup on module finalisation
 * @pdev: The platform device we are bound to.
 *
 * Shutdown and then release all the resources that the driver allocated
 * on initialisation.
 */
static int __devexit s3c_fb_remove(struct platform_device *pdev)
{
        struct s3c_fb *sfb = platform_get_drvdata(pdev);
        int win;

        for (win = 0; win < S3C_FB_MAX_WIN; win++)
                if (sfb->windows[win])
                        s3c_fb_release_win(sfb, sfb->windows[win]);

        iounmap(sfb->regs);

        clk_disable(sfb->bus_clk);
        clk_put(sfb->bus_clk);

        release_resource(sfb->regs_res);
        kfree(sfb->regs_res);

        kfree(sfb);

        return 0;
}

#ifdef CONFIG_PM
static int s3c_fb_suspend(struct platform_device *pdev, pm_message_t state)
{
        struct s3c_fb *sfb = platform_get_drvdata(pdev);
        struct s3c_fb_win *win;
        int win_no;

        for (win_no = S3C_FB_MAX_WIN - 1; win_no >= 0; win_no--) {
                win = sfb->windows[win_no];
                if (!win)
                        continue;

                /* use the blank function to push into power-down */
                s3c_fb_blank(FB_BLANK_POWERDOWN, win->fbinfo);
        }

        clk_disable(sfb->bus_clk);
        return 0;
}

static int s3c_fb_resume(struct platform_device *pdev)
{
        struct s3c_fb *sfb = platform_get_drvdata(pdev);
        struct s3c_fb_platdata *pd = sfb->pdata;
        struct s3c_fb_win *win;
        int win_no;

        clk_enable(sfb->bus_clk);

        /* setup registers */
        writel(pd->vidcon1, sfb->regs + VIDCON1);

        /* zero all windows before we do anything */
        for (win_no = 0; win_no < S3C_FB_MAX_WIN; win_no++)
                s3c_fb_clear_win(sfb, win_no);

        /* restore framebuffers */
        for (win_no = 0; win_no < S3C_FB_MAX_WIN; win_no++) {
                win = sfb->windows[win_no];
                if (!win)
                        continue;

                dev_dbg(&pdev->dev, "resuming window %d\n", win_no);
                s3c_fb_set_par(win->fbinfo);
        }

        return 0;
}
#else
#define s3c_fb_suspend NULL
#define s3c_fb_resume  NULL
#endif

static struct platform_driver s3c_fb_driver = {
        .probe          = s3c_fb_probe,
        .remove         = __devexit_p(s3c_fb_remove),
        .suspend        = s3c_fb_suspend,
        .resume         = s3c_fb_resume,
        .driver         = {
                .name   = "s3c-fb",
                .owner  = THIS_MODULE,
        },
};

static int __init s3c_fb_init(void)
{
        return platform_driver_register(&s3c_fb_driver);
}

static void __exit s3c_fb_cleanup(void)
{
        platform_driver_unregister(&s3c_fb_driver);
}

module_init(s3c_fb_init);
module_exit(s3c_fb_cleanup);

MODULE_AUTHOR("Ben Dooks <ben@simtec.co.uk>");
MODULE_DESCRIPTION("Samsung S3C SoC Framebuffer driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:s3c-fb");