/*
 *  Driver for AT91 LCD Controller
 *
 *  Copyright (C) 2007 Atmel Corporation
 *
 * 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.
 */

#include <linux/kernel.h>
#include <linux/platform_device.h>
#include <linux/dma-mapping.h>
#include <linux/interrupt.h>
#include <linux/clk.h>
#include <linux/fb.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/backlight.h>
#include <linux/gfp.h>
#include <linux/gpio/consumer.h>
#include <linux/module.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <video/of_videomode.h>
#include <video/of_display_timing.h>
#include <linux/regulator/consumer.h>
#include <video/videomode.h>

#include <video/atmel_lcdc.h>

struct atmel_lcdfb_config {
        bool have_alt_pixclock;
        bool have_hozval;
        bool have_intensity_bit;
};

 /* LCD Controller info data structure, stored in device platform_data */
struct atmel_lcdfb_info {
        spinlock_t              lock;
        struct fb_info          *info;
        void __iomem            *mmio;
        int                     irq_base;
        struct work_struct      task;

        unsigned int            smem_len;
        struct platform_device  *pdev;
        struct clk              *bus_clk;
        struct clk              *lcdc_clk;

        struct backlight_device *backlight;
        u8                      saved_lcdcon;

        u32                     pseudo_palette[16];
        bool                    have_intensity_bit;

        struct atmel_lcdfb_pdata pdata;

        struct atmel_lcdfb_config *config;
        struct regulator        *reg_lcd;
};

struct atmel_lcdfb_power_ctrl_gpio {
        struct gpio_desc *gpiod;

        struct list_head list;
};

#define lcdc_readl(sinfo, reg)          __raw_readl((sinfo)->mmio+(reg))
#define lcdc_writel(sinfo, reg, val)    __raw_writel((val), (sinfo)->mmio+(reg))

/* configurable parameters */
#define ATMEL_LCDC_CVAL_DEFAULT         0xc8
#define ATMEL_LCDC_DMA_BURST_LEN        8       /* words */
#define ATMEL_LCDC_FIFO_SIZE            512     /* words */

static struct atmel_lcdfb_config at91sam9261_config = {
        .have_hozval            = true,
        .have_intensity_bit     = true,
};

static struct atmel_lcdfb_config at91sam9263_config = {
        .have_intensity_bit     = true,
};

static struct atmel_lcdfb_config at91sam9g10_config = {
        .have_hozval            = true,
};

static struct atmel_lcdfb_config at91sam9g45_config = {
        .have_alt_pixclock      = true,
};

static struct atmel_lcdfb_config at91sam9g45es_config = {
};

static struct atmel_lcdfb_config at91sam9rl_config = {
        .have_intensity_bit     = true,
};

static u32 contrast_ctr = ATMEL_LCDC_PS_DIV8
                | ATMEL_LCDC_POL_POSITIVE
                | ATMEL_LCDC_ENA_PWMENABLE;

#ifdef CONFIG_BACKLIGHT_ATMEL_LCDC

/* some bl->props field just changed */
static int atmel_bl_update_status(struct backlight_device *bl)
{
        struct atmel_lcdfb_info *sinfo = bl_get_data(bl);
        int                     brightness = backlight_get_brightness(bl);

        lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_VAL, brightness);
        if (contrast_ctr & ATMEL_LCDC_POL_POSITIVE)
                lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_CTR,
                        brightness ? contrast_ctr : 0);
        else
                lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_CTR, contrast_ctr);

        return 0;
}

static int atmel_bl_get_brightness(struct backlight_device *bl)
{
        struct atmel_lcdfb_info *sinfo = bl_get_data(bl);

        return lcdc_readl(sinfo, ATMEL_LCDC_CONTRAST_VAL);
}

static const struct backlight_ops atmel_lcdc_bl_ops = {
        .update_status = atmel_bl_update_status,
        .get_brightness = atmel_bl_get_brightness,
};

static void init_backlight(struct atmel_lcdfb_info *sinfo)
{
        struct backlight_properties props;
        struct backlight_device *bl;

        if (sinfo->backlight)
                return;

        memset(&props, 0, sizeof(struct backlight_properties));
        props.type = BACKLIGHT_RAW;
        props.max_brightness = 0xff;
        bl = backlight_device_register("backlight", &sinfo->pdev->dev, sinfo,
                                       &atmel_lcdc_bl_ops, &props);
        if (IS_ERR(bl)) {
                dev_err(&sinfo->pdev->dev, "error %ld on backlight register\n",
                                PTR_ERR(bl));
                return;
        }
        sinfo->backlight = bl;

        bl->props.power = BACKLIGHT_POWER_ON;
        bl->props.brightness = atmel_bl_get_brightness(bl);
}

static void exit_backlight(struct atmel_lcdfb_info *sinfo)
{
        if (!sinfo->backlight)
                return;

        if (sinfo->backlight->ops) {
                sinfo->backlight->props.power = BACKLIGHT_POWER_OFF;
                sinfo->backlight->ops->update_status(sinfo->backlight);
        }
        backlight_device_unregister(sinfo->backlight);
}

#else

static void init_backlight(struct atmel_lcdfb_info *sinfo)
{
        dev_warn(&sinfo->pdev->dev, "backlight control is not available\n");
}

static void exit_backlight(struct atmel_lcdfb_info *sinfo)
{
}

#endif

static void init_contrast(struct atmel_lcdfb_info *sinfo)
{
        struct atmel_lcdfb_pdata *pdata = &sinfo->pdata;

        /* contrast pwm can be 'inverted' */
        if (pdata->lcdcon_pol_negative)
                contrast_ctr &= ~(ATMEL_LCDC_POL_POSITIVE);

        /* have some default contrast/backlight settings */
        lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_CTR, contrast_ctr);
        lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_VAL, ATMEL_LCDC_CVAL_DEFAULT);

        if (pdata->lcdcon_is_backlight)
                init_backlight(sinfo);
}

static inline void atmel_lcdfb_power_control(struct atmel_lcdfb_info *sinfo, int on)
{
        int ret;
        struct atmel_lcdfb_pdata *pdata = &sinfo->pdata;

        if (pdata->atmel_lcdfb_power_control)
                pdata->atmel_lcdfb_power_control(pdata, on);
        else if (sinfo->reg_lcd) {
                if (on) {
                        ret = regulator_enable(sinfo->reg_lcd);
                        if (ret)
                                dev_err(&sinfo->pdev->dev,
                                        "lcd regulator enable failed:   %d\n", ret);
                } else {
                        ret = regulator_disable(sinfo->reg_lcd);
                        if (ret)
                                dev_err(&sinfo->pdev->dev,
                                        "lcd regulator disable failed: %d\n", ret);
                }
        }
}

static const struct fb_fix_screeninfo atmel_lcdfb_fix = {
        .type           = FB_TYPE_PACKED_PIXELS,
        .visual         = FB_VISUAL_TRUECOLOR,
        .xpanstep       = 0,
        .ypanstep       = 1,
        .ywrapstep      = 0,
        .accel          = FB_ACCEL_NONE,
};

static unsigned long compute_hozval(struct atmel_lcdfb_info *sinfo,
                                                        unsigned long xres)
{
        unsigned long lcdcon2;
        unsigned long value;

        if (!sinfo->config->have_hozval)
                return xres;

        lcdcon2 = lcdc_readl(sinfo, ATMEL_LCDC_LCDCON2);
        value = xres;
        if ((lcdcon2 & ATMEL_LCDC_DISTYPE) != ATMEL_LCDC_DISTYPE_TFT) {
                /* STN display */
                if ((lcdcon2 & ATMEL_LCDC_DISTYPE) == ATMEL_LCDC_DISTYPE_STNCOLOR) {
                        value *= 3;
                }
                if ( (lcdcon2 & ATMEL_LCDC_IFWIDTH) == ATMEL_LCDC_IFWIDTH_4
                   || ( (lcdcon2 & ATMEL_LCDC_IFWIDTH) == ATMEL_LCDC_IFWIDTH_8
                      && (lcdcon2 & ATMEL_LCDC_SCANMOD) == ATMEL_LCDC_SCANMOD_DUAL ))
                        value = DIV_ROUND_UP(value, 4);
                else
                        value = DIV_ROUND_UP(value, 8);
        }

        return value;
}

static void atmel_lcdfb_stop_nowait(struct atmel_lcdfb_info *sinfo)
{
        struct atmel_lcdfb_pdata *pdata = &sinfo->pdata;

        /* Turn off the LCD controller and the DMA controller */
        lcdc_writel(sinfo, ATMEL_LCDC_PWRCON,
                        pdata->guard_time << ATMEL_LCDC_GUARDT_OFFSET);

        /* Wait for the LCDC core to become idle */
        while (lcdc_readl(sinfo, ATMEL_LCDC_PWRCON) & ATMEL_LCDC_BUSY)
                msleep(10);

        lcdc_writel(sinfo, ATMEL_LCDC_DMACON, 0);
}

static void atmel_lcdfb_stop(struct atmel_lcdfb_info *sinfo)
{
        atmel_lcdfb_stop_nowait(sinfo);

        /* Wait for DMA engine to become idle... */
        while (lcdc_readl(sinfo, ATMEL_LCDC_DMACON) & ATMEL_LCDC_DMABUSY)
                msleep(10);
}

static void atmel_lcdfb_start(struct atmel_lcdfb_info *sinfo)
{
        struct atmel_lcdfb_pdata *pdata = &sinfo->pdata;

        lcdc_writel(sinfo, ATMEL_LCDC_DMACON, pdata->default_dmacon);
        lcdc_writel(sinfo, ATMEL_LCDC_PWRCON,
                (pdata->guard_time << ATMEL_LCDC_GUARDT_OFFSET)
                | ATMEL_LCDC_PWR);
}

static void atmel_lcdfb_update_dma(struct fb_info *info,
                               struct fb_var_screeninfo *var)
{
        struct atmel_lcdfb_info *sinfo = info->par;
        struct fb_fix_screeninfo *fix = &info->fix;
        unsigned long dma_addr;

        dma_addr = (fix->smem_start + var->yoffset * fix->line_length
                    + var->xoffset * info->var.bits_per_pixel / 8);

        dma_addr &= ~3UL;

        /* Set framebuffer DMA base address and pixel offset */
        lcdc_writel(sinfo, ATMEL_LCDC_DMABADDR1, dma_addr);
}

static inline void atmel_lcdfb_free_video_memory(struct atmel_lcdfb_info *sinfo)
{
        struct fb_info *info = sinfo->info;

        dma_free_wc(info->device, info->fix.smem_len, info->screen_base,
                    info->fix.smem_start);
}

/**
 *      atmel_lcdfb_alloc_video_memory - Allocate framebuffer memory
 *      @sinfo: the frame buffer to allocate memory for
 *
 *      This function is called only from the atmel_lcdfb_probe()
 *      so no locking by fb_info->mm_lock around smem_len setting is needed.
 */
static int atmel_lcdfb_alloc_video_memory(struct atmel_lcdfb_info *sinfo)
{
        struct fb_info *info = sinfo->info;
        struct fb_var_screeninfo *var = &info->var;
        unsigned int smem_len;

        smem_len = (var->xres_virtual * var->yres_virtual
                    * ((var->bits_per_pixel + 7) / 8));
        info->fix.smem_len = max(smem_len, sinfo->smem_len);

        info->screen_base = dma_alloc_wc(info->device, info->fix.smem_len,
                                         (dma_addr_t *)&info->fix.smem_start,
                                         GFP_KERNEL);

        if (!info->screen_base) {
                return -ENOMEM;
        }

        memset(info->screen_base, 0, info->fix.smem_len);

        return 0;
}

static const struct fb_videomode *atmel_lcdfb_choose_mode(struct fb_var_screeninfo *var,
                                                     struct fb_info *info)
{
        struct fb_videomode varfbmode;
        const struct fb_videomode *fbmode = NULL;

        fb_var_to_videomode(&varfbmode, var);
        fbmode = fb_find_nearest_mode(&varfbmode, &info->modelist);
        if (fbmode)
                fb_videomode_to_var(var, fbmode);
        return fbmode;
}


/**
 *      atmel_lcdfb_check_var - Validates a var passed in.
 *      @var: frame buffer variable screen structure
 *      @info: frame buffer structure that represents a single frame buffer
 *
 *      Checks to see if the hardware supports the state requested by
 *      var passed in. This function does not alter the hardware
 *      state!!!  This means the data stored in struct fb_info and
 *      struct atmel_lcdfb_info do not change. This includes the var
 *      inside of struct fb_info.  Do NOT change these. This function
 *      can be called on its own if we intent to only test a mode and
 *      not actually set it. The stuff in modedb.c is a example of
 *      this. If the var passed in is slightly off by what the
 *      hardware can support then we alter the var PASSED in to what
 *      we can do. If the hardware doesn't support mode change a
 *      -EINVAL will be returned by the upper layers. You don't need
 *      to implement this function then. If you hardware doesn't
 *      support changing the resolution then this function is not
 *      needed. In this case the driver would just provide a var that
 *      represents the static state the screen is in.
 *
 *      Returns negative errno on error, or zero on success.
 */
static int atmel_lcdfb_check_var(struct fb_var_screeninfo *var,
                             struct fb_info *info)
{
        struct device *dev = info->device;
        struct atmel_lcdfb_info *sinfo = info->par;
        struct atmel_lcdfb_pdata *pdata = &sinfo->pdata;
        unsigned long clk_value_khz;

        clk_value_khz = clk_get_rate(sinfo->lcdc_clk) / 1000;

        dev_dbg(dev, "%s:\n", __func__);

        if (!(var->pixclock && var->bits_per_pixel)) {
                /* choose a suitable mode if possible */
                if (!atmel_lcdfb_choose_mode(var, info)) {
                        dev_err(dev, "needed value not specified\n");
                        return -EINVAL;
                }
        }

        dev_dbg(dev, "  resolution: %ux%u\n", var->xres, var->yres);
        dev_dbg(dev, "  pixclk:     %lu KHz\n", PICOS2KHZ(var->pixclock));
        dev_dbg(dev, "  bpp:        %u\n", var->bits_per_pixel);
        dev_dbg(dev, "  clk:        %lu KHz\n", clk_value_khz);

        if (PICOS2KHZ(var->pixclock) > clk_value_khz) {
                dev_err(dev, "%lu KHz pixel clock is too fast\n", PICOS2KHZ(var->pixclock));
                return -EINVAL;
        }

        /* Do not allow to have real resoulution larger than virtual */
        if (var->xres > var->xres_virtual)
                var->xres_virtual = var->xres;

        if (var->yres > var->yres_virtual)
                var->yres_virtual = var->yres;

        /* Force same alignment for each line */
        var->xres = (var->xres + 3) & ~3UL;
        var->xres_virtual = (var->xres_virtual + 3) & ~3UL;

        var->red.msb_right = var->green.msb_right = var->blue.msb_right = 0;
        var->transp.msb_right = 0;
        var->transp.offset = var->transp.length = 0;
        var->xoffset = var->yoffset = 0;

        if (info->fix.smem_len) {
                unsigned int smem_len = (var->xres_virtual * var->yres_virtual
                                         * ((var->bits_per_pixel + 7) / 8));
                if (smem_len > info->fix.smem_len) {
                        dev_err(dev, "Frame buffer is too small (%u) for screen size (need at least %u)\n",
                                info->fix.smem_len, smem_len);
                        return -EINVAL;
                }
        }

        /* Saturate vertical and horizontal timings at maximum values */
        var->vsync_len = min_t(u32, var->vsync_len,
                        (ATMEL_LCDC_VPW >> ATMEL_LCDC_VPW_OFFSET) + 1);
        var->upper_margin = min_t(u32, var->upper_margin,
                        ATMEL_LCDC_VBP >> ATMEL_LCDC_VBP_OFFSET);
        var->lower_margin = min_t(u32, var->lower_margin,
                        ATMEL_LCDC_VFP);
        var->right_margin = min_t(u32, var->right_margin,
                        (ATMEL_LCDC_HFP >> ATMEL_LCDC_HFP_OFFSET) + 1);
        var->hsync_len = min_t(u32, var->hsync_len,
                        (ATMEL_LCDC_HPW >> ATMEL_LCDC_HPW_OFFSET) + 1);
        var->left_margin = min_t(u32, var->left_margin,
                        ATMEL_LCDC_HBP + 1);

        /* Some parameters can't be zero */
        var->vsync_len = max_t(u32, var->vsync_len, 1);
        var->right_margin = max_t(u32, var->right_margin, 1);
        var->hsync_len = max_t(u32, var->hsync_len, 1);
        var->left_margin = max_t(u32, var->left_margin, 1);

        switch (var->bits_per_pixel) {
        case 1:
        case 2:
        case 4:
        case 8:
                var->red.offset = var->green.offset = var->blue.offset = 0;
                var->red.length = var->green.length = var->blue.length
                        = var->bits_per_pixel;
                break;
        case 16:
                /* Older SOCs use IBGR:555 rather than BGR:565. */
                if (sinfo->config->have_intensity_bit)
                        var->green.length = 5;
                else
                        var->green.length = 6;

                if (pdata->lcd_wiring_mode == ATMEL_LCDC_WIRING_RGB) {
                        /* RGB:5X5 mode */
                        var->red.offset = var->green.length + 5;
                        var->blue.offset = 0;
                } else {
                        /* BGR:5X5 mode */
                        var->red.offset = 0;
                        var->blue.offset = var->green.length + 5;
                }
                var->green.offset = 5;
                var->red.length = var->blue.length = 5;
                break;
        case 32:
                var->transp.offset = 24;
                var->transp.length = 8;
                fallthrough;
        case 24:
                if (pdata->lcd_wiring_mode == ATMEL_LCDC_WIRING_RGB) {
                        /* RGB:888 mode */
                        var->red.offset = 16;
                        var->blue.offset = 0;
                } else {
                        /* BGR:888 mode */
                        var->red.offset = 0;
                        var->blue.offset = 16;
                }
                var->green.offset = 8;
                var->red.length = var->green.length = var->blue.length = 8;
                break;
        default:
                dev_err(dev, "color depth %d not supported\n",
                                        var->bits_per_pixel);
                return -EINVAL;
        }

        return 0;
}

/*
 * LCD reset sequence
 */
static void atmel_lcdfb_reset(struct atmel_lcdfb_info *sinfo)
{
        might_sleep();

        atmel_lcdfb_stop(sinfo);
        atmel_lcdfb_start(sinfo);
}

/**
 *      atmel_lcdfb_set_par - Alters the hardware state.
 *      @info: frame buffer structure that represents a single frame buffer
 *
 *      Using the fb_var_screeninfo in fb_info we set the resolution
 *      of the this particular framebuffer. This function alters the
 *      par AND the fb_fix_screeninfo stored in fb_info. It doesn't
 *      not alter var in fb_info since we are using that data. This
 *      means we depend on the data in var inside fb_info to be
 *      supported by the hardware.  atmel_lcdfb_check_var is always called
 *      before atmel_lcdfb_set_par to ensure this.  Again if you can't
 *      change the resolution you don't need this function.
 *
 */
static int atmel_lcdfb_set_par(struct fb_info *info)
{
        struct atmel_lcdfb_info *sinfo = info->par;
        struct atmel_lcdfb_pdata *pdata = &sinfo->pdata;
        unsigned long hozval_linesz;
        unsigned long value;
        unsigned long clk_value_khz;
        unsigned long bits_per_line;
        unsigned long pix_factor = 2;

        might_sleep();

        dev_dbg(info->device, "%s:\n", __func__);
        dev_dbg(info->device, "  * resolution: %ux%u (%ux%u virtual)\n",
                 info->var.xres, info->var.yres,
                 info->var.xres_virtual, info->var.yres_virtual);

        atmel_lcdfb_stop_nowait(sinfo);

        if (info->var.bits_per_pixel == 1)
                info->fix.visual = FB_VISUAL_MONO01;
        else if (info->var.bits_per_pixel <= 8)
                info->fix.visual = FB_VISUAL_PSEUDOCOLOR;
        else
                info->fix.visual = FB_VISUAL_TRUECOLOR;

        bits_per_line = info->var.xres_virtual * info->var.bits_per_pixel;
        info->fix.line_length = DIV_ROUND_UP(bits_per_line, 8);

        /* Re-initialize the DMA engine... */
        dev_dbg(info->device, "  * update DMA engine\n");
        atmel_lcdfb_update_dma(info, &info->var);

        /* ...set frame size and burst length = 8 words (?) */
        value = (info->var.yres * info->var.xres * info->var.bits_per_pixel) / 32;
        value |= ((ATMEL_LCDC_DMA_BURST_LEN - 1) << ATMEL_LCDC_BLENGTH_OFFSET);
        lcdc_writel(sinfo, ATMEL_LCDC_DMAFRMCFG, value);

        /* Now, the LCDC core... */

        /* Set pixel clock */
        if (sinfo->config->have_alt_pixclock)
                pix_factor = 1;

        clk_value_khz = clk_get_rate(sinfo->lcdc_clk) / 1000;

        value = DIV_ROUND_UP(clk_value_khz, PICOS2KHZ(info->var.pixclock));

        if (value < pix_factor) {
                dev_notice(info->device, "Bypassing pixel clock divider\n");
                lcdc_writel(sinfo, ATMEL_LCDC_LCDCON1, ATMEL_LCDC_BYPASS);
        } else {
                value = (value / pix_factor) - 1;
                dev_dbg(info->device, "  * programming CLKVAL = 0x%08lx\n",
                                value);
                lcdc_writel(sinfo, ATMEL_LCDC_LCDCON1,
                                value << ATMEL_LCDC_CLKVAL_OFFSET);
                info->var.pixclock =
                        KHZ2PICOS(clk_value_khz / (pix_factor * (value + 1)));
                dev_dbg(info->device, "  updated pixclk:     %lu KHz\n",
                                        PICOS2KHZ(info->var.pixclock));
        }


        /* Initialize control register 2 */
        value = pdata->default_lcdcon2;

        if (!(info->var.sync & FB_SYNC_HOR_HIGH_ACT))
                value |= ATMEL_LCDC_INVLINE_INVERTED;
        if (!(info->var.sync & FB_SYNC_VERT_HIGH_ACT))
                value |= ATMEL_LCDC_INVFRAME_INVERTED;

        switch (info->var.bits_per_pixel) {
                case 1: value |= ATMEL_LCDC_PIXELSIZE_1; break;
                case 2: value |= ATMEL_LCDC_PIXELSIZE_2; break;
                case 4: value |= ATMEL_LCDC_PIXELSIZE_4; break;
                case 8: value |= ATMEL_LCDC_PIXELSIZE_8; break;
                case 15: fallthrough;
                case 16: value |= ATMEL_LCDC_PIXELSIZE_16; break;
                case 24: value |= ATMEL_LCDC_PIXELSIZE_24; break;
                case 32: value |= ATMEL_LCDC_PIXELSIZE_32; break;
                default: BUG(); break;
        }
        dev_dbg(info->device, "  * LCDCON2 = %08lx\n", value);
        lcdc_writel(sinfo, ATMEL_LCDC_LCDCON2, value);

        /* Vertical timing */
        value = (info->var.vsync_len - 1) << ATMEL_LCDC_VPW_OFFSET;
        value |= info->var.upper_margin << ATMEL_LCDC_VBP_OFFSET;
        value |= info->var.lower_margin;
        dev_dbg(info->device, "  * LCDTIM1 = %08lx\n", value);
        lcdc_writel(sinfo, ATMEL_LCDC_TIM1, value);

        /* Horizontal timing */
        value = (info->var.right_margin - 1) << ATMEL_LCDC_HFP_OFFSET;
        value |= (info->var.hsync_len - 1) << ATMEL_LCDC_HPW_OFFSET;
        value |= (info->var.left_margin - 1);
        dev_dbg(info->device, "  * LCDTIM2 = %08lx\n", value);
        lcdc_writel(sinfo, ATMEL_LCDC_TIM2, value);

        /* Horizontal value (aka line size) */
        hozval_linesz = compute_hozval(sinfo, info->var.xres);

        /* Display size */
        value = (hozval_linesz - 1) << ATMEL_LCDC_HOZVAL_OFFSET;
        value |= info->var.yres - 1;
        dev_dbg(info->device, "  * LCDFRMCFG = %08lx\n", value);
        lcdc_writel(sinfo, ATMEL_LCDC_LCDFRMCFG, value);

        /* FIFO Threshold: Use formula from data sheet */
        value = ATMEL_LCDC_FIFO_SIZE - (2 * ATMEL_LCDC_DMA_BURST_LEN + 3);
        lcdc_writel(sinfo, ATMEL_LCDC_FIFO, value);

        /* Toggle LCD_MODE every frame */
        lcdc_writel(sinfo, ATMEL_LCDC_MVAL, 0);

        /* Disable all interrupts */
        lcdc_writel(sinfo, ATMEL_LCDC_IDR, ~0U);
        /* Enable FIFO & DMA errors */
        lcdc_writel(sinfo, ATMEL_LCDC_IER, ATMEL_LCDC_UFLWI | ATMEL_LCDC_OWRI | ATMEL_LCDC_MERI);

        /* ...wait for DMA engine to become idle... */
        while (lcdc_readl(sinfo, ATMEL_LCDC_DMACON) & ATMEL_LCDC_DMABUSY)
                msleep(10);

        atmel_lcdfb_start(sinfo);

        dev_dbg(info->device, "  * DONE\n");

        return 0;
}

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

/**
 *      atmel_lcdfb_setcolreg - Optional function. Sets a color register.
 *      @regno: Which register in the CLUT we are programming
 *      @red: The red value which can be up to 16 bits wide
 *      @green: The green value which can be up to 16 bits wide
 *      @blue:  The blue value which can be up to 16 bits wide.
 *      @transp: If supported the alpha value which can be up to 16 bits wide.
 *      @info: frame buffer info structure
 *
 *      Set a single color register. The values supplied have a 16 bit
 *      magnitude which needs to be scaled in this function for the hardware.
 *      Things to take into consideration are how many color registers, if
 *      any, are supported with the current color visual. With truecolor mode
 *      no color palettes are supported. Here a pseudo palette is created
 *      which we store the value in pseudo_palette in struct fb_info. For
 *      pseudocolor mode we have a limited color palette. To deal with this
 *      we can program what color is displayed for a particular pixel value.
 *      DirectColor is similar in that we can program each color field. If
 *      we have a static colormap we don't need to implement this function.
 *
 *      Returns negative errno on error, or zero on success. In an
 *      ideal world, this would have been the case, but as it turns
 *      out, the other drivers return 1 on failure, so that's what
 *      we're going to do.
 */
static int atmel_lcdfb_setcolreg(unsigned int regno, unsigned int red,
                             unsigned int green, unsigned int blue,
                             unsigned int transp, struct fb_info *info)
{
        struct atmel_lcdfb_info *sinfo = info->par;
        struct atmel_lcdfb_pdata *pdata = &sinfo->pdata;
        unsigned int val;
        u32 *pal;
        int ret = 1;

        if (info->var.grayscale)
                red = green = blue = (19595 * red + 38470 * green
                                      + 7471 * blue) >> 16;

        switch (info->fix.visual) {
        case FB_VISUAL_TRUECOLOR:
                if (regno < 16) {
                        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;
                        ret = 0;
                }
                break;

        case FB_VISUAL_PSEUDOCOLOR:
                if (regno < 256) {
                        if (sinfo->config->have_intensity_bit) {
                                /* old style I+BGR:555 */
                                val  = ((red   >> 11) & 0x001f);
                                val |= ((green >>  6) & 0x03e0);
                                val |= ((blue  >>  1) & 0x7c00);

                                /*
                                 * TODO: intensity bit. Maybe something like
                                 *   ~(red[10] ^ green[10] ^ blue[10]) & 1
                                 */
                        } else {
                                /* new style BGR:565 / RGB:565 */
                                if (pdata->lcd_wiring_mode == ATMEL_LCDC_WIRING_RGB) {
                                        val  = ((blue >> 11) & 0x001f);
                                        val |= ((red  >>  0) & 0xf800);
                                } else {
                                        val  = ((red  >> 11) & 0x001f);
                                        val |= ((blue >>  0) & 0xf800);
                                }

                                val |= ((green >>  5) & 0x07e0);
                        }

                        lcdc_writel(sinfo, ATMEL_LCDC_LUT(regno), val);
                        ret = 0;
                }
                break;

        case FB_VISUAL_MONO01:
                if (regno < 2) {
                        val = (regno == 0) ? 0x00 : 0x1F;
                        lcdc_writel(sinfo, ATMEL_LCDC_LUT(regno), val);
                        ret = 0;
                }
                break;

        }

        return ret;
}

static int atmel_lcdfb_pan_display(struct fb_var_screeninfo *var,
                               struct fb_info *info)
{
        dev_dbg(info->device, "%s\n", __func__);

        atmel_lcdfb_update_dma(info, var);

        return 0;
}

static int atmel_lcdfb_blank(int blank_mode, struct fb_info *info)
{
        struct atmel_lcdfb_info *sinfo = info->par;

        switch (blank_mode) {
        case FB_BLANK_UNBLANK:
        case FB_BLANK_NORMAL:
                atmel_lcdfb_start(sinfo);
                break;
        case FB_BLANK_VSYNC_SUSPEND:
        case FB_BLANK_HSYNC_SUSPEND:
                break;
        case FB_BLANK_POWERDOWN:
                atmel_lcdfb_stop(sinfo);
                break;
        default:
                return -EINVAL;
        }

        /* let fbcon do a soft blank for us */
        return ((blank_mode == FB_BLANK_NORMAL) ? 1 : 0);
}

static const struct fb_ops atmel_lcdfb_ops = {
        .owner          = THIS_MODULE,
        FB_DEFAULT_IOMEM_OPS,
        .fb_check_var   = atmel_lcdfb_check_var,
        .fb_set_par     = atmel_lcdfb_set_par,
        .fb_setcolreg   = atmel_lcdfb_setcolreg,
        .fb_blank       = atmel_lcdfb_blank,
        .fb_pan_display = atmel_lcdfb_pan_display,
};

static irqreturn_t atmel_lcdfb_interrupt(int irq, void *dev_id)
{
        struct fb_info *info = dev_id;
        struct atmel_lcdfb_info *sinfo = info->par;
        u32 status;

        status = lcdc_readl(sinfo, ATMEL_LCDC_ISR);
        if (status & ATMEL_LCDC_UFLWI) {
                dev_warn(info->device, "FIFO underflow %#x\n", status);
                /* reset DMA and FIFO to avoid screen shifting */
                schedule_work(&sinfo->task);
        }
        lcdc_writel(sinfo, ATMEL_LCDC_ICR, status);
        return IRQ_HANDLED;
}

/*
 * LCD controller task (to reset the LCD)
 */
static void atmel_lcdfb_task(struct work_struct *work)
{
        struct atmel_lcdfb_info *sinfo =
                container_of(work, struct atmel_lcdfb_info, task);

        atmel_lcdfb_reset(sinfo);
}

static int atmel_lcdfb_init_fbinfo(struct atmel_lcdfb_info *sinfo)
{
        struct fb_info *info = sinfo->info;
        int ret = 0;

        info->var.activate |= FB_ACTIVATE_FORCE | FB_ACTIVATE_NOW;

        dev_info(info->device,
               "%luKiB frame buffer at %08lx (mapped at %p)\n",
               (unsigned long)info->fix.smem_len / 1024,
               (unsigned long)info->fix.smem_start,
               info->screen_base);

        /* Allocate colormap */
        ret = fb_alloc_cmap(&info->cmap, 256, 0);
        if (ret < 0)
                dev_err(info->device, "Alloc color map failed\n");

        return ret;
}

static void atmel_lcdfb_start_clock(struct atmel_lcdfb_info *sinfo)
{
        clk_prepare_enable(sinfo->bus_clk);
        clk_prepare_enable(sinfo->lcdc_clk);
}

static void atmel_lcdfb_stop_clock(struct atmel_lcdfb_info *sinfo)
{
        clk_disable_unprepare(sinfo->bus_clk);
        clk_disable_unprepare(sinfo->lcdc_clk);
}

static const struct of_device_id atmel_lcdfb_dt_ids[] = {
        { .compatible = "atmel,at91sam9261-lcdc" , .data = &at91sam9261_config, },
        { .compatible = "atmel,at91sam9263-lcdc" , .data = &at91sam9263_config, },
        { .compatible = "atmel,at91sam9g10-lcdc" , .data = &at91sam9g10_config, },
        { .compatible = "atmel,at91sam9g45-lcdc" , .data = &at91sam9g45_config, },
        { .compatible = "atmel,at91sam9g45es-lcdc" , .data = &at91sam9g45es_config, },
        { .compatible = "atmel,at91sam9rl-lcdc" , .data = &at91sam9rl_config, },
        { /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, atmel_lcdfb_dt_ids);

static const char *atmel_lcdfb_wiring_modes[] = {
        [ATMEL_LCDC_WIRING_BGR] = "BRG",
        [ATMEL_LCDC_WIRING_RGB] = "RGB",
};

static int atmel_lcdfb_get_of_wiring_modes(struct device_node *np)
{
        const char *mode;
        int err, i;

        err = of_property_read_string(np, "atmel,lcd-wiring-mode", &mode);
        if (err < 0)
                return ATMEL_LCDC_WIRING_BGR;

        for (i = 0; i < ARRAY_SIZE(atmel_lcdfb_wiring_modes); i++)
                if (!strcasecmp(mode, atmel_lcdfb_wiring_modes[i]))
                        return i;

        return -ENODEV;
}

static void atmel_lcdfb_power_control_gpio(struct atmel_lcdfb_pdata *pdata, int on)
{
        struct atmel_lcdfb_power_ctrl_gpio *og;

        list_for_each_entry(og, &pdata->pwr_gpios, list)
                gpiod_set_value(og->gpiod, on);
}

static int atmel_lcdfb_of_init(struct atmel_lcdfb_info *sinfo)
{
        struct fb_info *info = sinfo->info;
        struct atmel_lcdfb_pdata *pdata = &sinfo->pdata;
        struct fb_var_screeninfo *var = &info->var;
        struct device *dev = &sinfo->pdev->dev;
        struct device_node *np =dev->of_node;
        struct device_node *display_np;
        struct atmel_lcdfb_power_ctrl_gpio *og;
        bool is_gpio_power = false;
        struct fb_videomode fb_vm;
        struct gpio_desc *gpiod;
        struct videomode vm;
        int ret;
        int i;

        sinfo->config = (struct atmel_lcdfb_config*)
                of_match_device(atmel_lcdfb_dt_ids, dev)->data;

        display_np = of_parse_phandle(np, "display", 0);
        if (!display_np) {
                dev_err(dev, "failed to find display phandle\n");
                return -ENOENT;
        }

        ret = of_property_read_u32(display_np, "bits-per-pixel", &var->bits_per_pixel);
        if (ret < 0) {
                dev_err(dev, "failed to get property bits-per-pixel\n");
                goto put_display_node;
        }

        ret = of_property_read_u32(display_np, "atmel,guard-time", &pdata->guard_time);
        if (ret < 0) {
                dev_err(dev, "failed to get property atmel,guard-time\n");
                goto put_display_node;
        }

        ret = of_property_read_u32(display_np, "atmel,lcdcon2", &pdata->default_lcdcon2);
        if (ret < 0) {
                dev_err(dev, "failed to get property atmel,lcdcon2\n");
                goto put_display_node;
        }

        ret = of_property_read_u32(display_np, "atmel,dmacon", &pdata->default_dmacon);
        if (ret < 0) {
                dev_err(dev, "failed to get property bits-per-pixel\n");
                goto put_display_node;
        }

        INIT_LIST_HEAD(&pdata->pwr_gpios);
        for (i = 0; i < gpiod_count(dev, "atmel,power-control"); i++) {
                ret = -ENOMEM;
                gpiod = devm_gpiod_get_index(dev, "atmel,power-control",
                                             i, GPIOD_ASIS);
                if (IS_ERR(gpiod))
                        continue;

                og = devm_kzalloc(dev, sizeof(*og), GFP_KERNEL);
                if (!og)
                        goto put_display_node;

                og->gpiod = gpiod;
                is_gpio_power = true;

                ret = gpiod_direction_output(gpiod, gpiod_is_active_low(gpiod));
                if (ret) {
                        dev_err(dev, "set direction output gpio atmel,power-control[%d] failed\n", i);
                        goto put_display_node;
                }
                list_add(&og->list, &pdata->pwr_gpios);
        }

        if (is_gpio_power)
                pdata->atmel_lcdfb_power_control = atmel_lcdfb_power_control_gpio;

        ret = atmel_lcdfb_get_of_wiring_modes(display_np);
        if (ret < 0) {
                dev_err(dev, "invalid atmel,lcd-wiring-mode\n");
                goto put_display_node;
        }
        pdata->lcd_wiring_mode = ret;

        pdata->lcdcon_is_backlight = of_property_read_bool(display_np, "atmel,lcdcon-backlight");
        pdata->lcdcon_pol_negative = of_property_read_bool(display_np, "atmel,lcdcon-backlight-inverted");

        ret = of_get_videomode(display_np, &vm, OF_USE_NATIVE_MODE);
        if (ret) {
                dev_err(dev, "failed to get videomode from DT\n");
                goto put_display_node;
        }

        ret = fb_videomode_from_videomode(&vm, &fb_vm);
        if (ret < 0)
                goto put_display_node;

        fb_add_videomode(&fb_vm, &info->modelist);

put_display_node:
        of_node_put(display_np);
        return ret;
}

static int atmel_lcdfb_probe(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct fb_info *info;
        struct atmel_lcdfb_info *sinfo;
        struct resource *regs = NULL;
        struct resource *map = NULL;
        struct fb_modelist *modelist;
        int ret;

        dev_dbg(dev, "%s BEGIN\n", __func__);

        ret = -ENOMEM;
        info = framebuffer_alloc(sizeof(struct atmel_lcdfb_info), dev);
        if (!info)
                goto out;

        sinfo = info->par;
        sinfo->pdev = pdev;
        sinfo->info = info;

        INIT_LIST_HEAD(&info->modelist);

        if (!pdev->dev.of_node) {
                dev_err(dev, "cannot get default configuration\n");
                goto free_info;
        }

        ret = atmel_lcdfb_of_init(sinfo);
        if (ret)
                goto free_info;

        ret = -ENODEV;
        if (!sinfo->config)
                goto free_info;

        sinfo->reg_lcd = devm_regulator_get(&pdev->dev, "lcd");
        if (IS_ERR(sinfo->reg_lcd))
                sinfo->reg_lcd = NULL;

        info->flags = FBINFO_PARTIAL_PAN_OK |
                      FBINFO_HWACCEL_YPAN;
        info->pseudo_palette = sinfo->pseudo_palette;
        info->fbops = &atmel_lcdfb_ops;

        info->fix = atmel_lcdfb_fix;
        strcpy(info->fix.id, sinfo->pdev->name);

        /* Enable LCDC Clocks */
        sinfo->bus_clk = clk_get(dev, "hclk");
        if (IS_ERR(sinfo->bus_clk)) {
                ret = PTR_ERR(sinfo->bus_clk);
                goto free_info;
        }
        sinfo->lcdc_clk = clk_get(dev, "lcdc_clk");
        if (IS_ERR(sinfo->lcdc_clk)) {
                ret = PTR_ERR(sinfo->lcdc_clk);
                goto put_bus_clk;
        }
        atmel_lcdfb_start_clock(sinfo);

        modelist = list_first_entry(&info->modelist,
                        struct fb_modelist, list);
        fb_videomode_to_var(&info->var, &modelist->mode);

        atmel_lcdfb_check_var(&info->var, info);

        regs = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!regs) {
                dev_err(dev, "resources unusable\n");
                ret = -ENXIO;
                goto stop_clk;
        }

        sinfo->irq_base = platform_get_irq(pdev, 0);
        if (sinfo->irq_base < 0) {
                ret = sinfo->irq_base;
                goto stop_clk;
        }

        /* Initialize video memory */
        map = platform_get_resource(pdev, IORESOURCE_MEM, 1);
        if (map) {
                /* use a pre-allocated memory buffer */
                info->fix.smem_start = map->start;
                info->fix.smem_len = resource_size(map);
                if (!request_mem_region(info->fix.smem_start,
                                        info->fix.smem_len, pdev->name)) {
                        ret = -EBUSY;
                        goto stop_clk;
                }

                info->screen_base = ioremap_wc(info->fix.smem_start,
                                               info->fix.smem_len);
                if (!info->screen_base) {
                        ret = -ENOMEM;
                        goto release_intmem;
                }

                /*
                 * Don't clear the framebuffer -- someone may have set
                 * up a splash image.
                 */
        } else {
                /* allocate memory buffer */
                ret = atmel_lcdfb_alloc_video_memory(sinfo);
                if (ret < 0) {
                        dev_err(dev, "cannot allocate framebuffer: %d\n", ret);
                        goto stop_clk;
                }
        }

        /* LCDC registers */
        info->fix.mmio_start = regs->start;
        info->fix.mmio_len = resource_size(regs);

        if (!request_mem_region(info->fix.mmio_start,
                                info->fix.mmio_len, pdev->name)) {
                ret = -EBUSY;
                goto free_fb;
        }

        sinfo->mmio = ioremap(info->fix.mmio_start, info->fix.mmio_len);
        if (!sinfo->mmio) {
                dev_err(dev, "cannot map LCDC registers\n");
                ret = -ENOMEM;
                goto release_mem;
        }

        /* Initialize PWM for contrast or backlight ("off") */
        init_contrast(sinfo);

        /* interrupt */
        ret = request_irq(sinfo->irq_base, atmel_lcdfb_interrupt, 0, pdev->name, info);
        if (ret) {
                dev_err(dev, "request_irq failed: %d\n", ret);
                goto unmap_mmio;
        }

        /* Some operations on the LCDC might sleep and
         * require a preemptible task context */
        INIT_WORK(&sinfo->task, atmel_lcdfb_task);

        ret = atmel_lcdfb_init_fbinfo(sinfo);
        if (ret < 0) {
                dev_err(dev, "init fbinfo failed: %d\n", ret);
                goto unregister_irqs;
        }

        ret = atmel_lcdfb_set_par(info);
        if (ret < 0) {
                dev_err(dev, "set par failed: %d\n", ret);
                goto unregister_irqs;
        }

        dev_set_drvdata(dev, info);

        /*
         * Tell the world that we're ready to go
         */
        ret = register_framebuffer(info);
        if (ret < 0) {
                dev_err(dev, "failed to register framebuffer device: %d\n", ret);
                goto reset_drvdata;
        }

        /* Power up the LCDC screen */
        atmel_lcdfb_power_control(sinfo, 1);

        dev_info(dev, "fb%d: Atmel LCDC at 0x%08lx (mapped at %p), irq %d\n",
                       info->node, info->fix.mmio_start, sinfo->mmio, sinfo->irq_base);

        return 0;

reset_drvdata:
        dev_set_drvdata(dev, NULL);
        fb_dealloc_cmap(&info->cmap);
unregister_irqs:
        cancel_work_sync(&sinfo->task);
        free_irq(sinfo->irq_base, info);
unmap_mmio:
        exit_backlight(sinfo);
        iounmap(sinfo->mmio);
release_mem:
        release_mem_region(info->fix.mmio_start, info->fix.mmio_len);
free_fb:
        if (map)
                iounmap(info->screen_base);
        else
                atmel_lcdfb_free_video_memory(sinfo);

release_intmem:
        if (map)
                release_mem_region(info->fix.smem_start, info->fix.smem_len);
stop_clk:
        atmel_lcdfb_stop_clock(sinfo);
        clk_put(sinfo->lcdc_clk);
put_bus_clk:
        clk_put(sinfo->bus_clk);
free_info:
        framebuffer_release(info);
out:
        dev_dbg(dev, "%s FAILED\n", __func__);
        return ret;
}

static void atmel_lcdfb_remove(struct platform_device *pdev)
{
        struct device *dev = &pdev->dev;
        struct fb_info *info = dev_get_drvdata(dev);
        struct atmel_lcdfb_info *sinfo;

        if (!info || !info->par)
                return;
        sinfo = info->par;

        cancel_work_sync(&sinfo->task);
        exit_backlight(sinfo);
        atmel_lcdfb_power_control(sinfo, 0);
        unregister_framebuffer(info);
        atmel_lcdfb_stop_clock(sinfo);
        clk_put(sinfo->lcdc_clk);
        clk_put(sinfo->bus_clk);
        fb_dealloc_cmap(&info->cmap);
        free_irq(sinfo->irq_base, info);
        iounmap(sinfo->mmio);
        release_mem_region(info->fix.mmio_start, info->fix.mmio_len);
        if (platform_get_resource(pdev, IORESOURCE_MEM, 1)) {
                iounmap(info->screen_base);
                release_mem_region(info->fix.smem_start, info->fix.smem_len);
        } else {
                atmel_lcdfb_free_video_memory(sinfo);
        }

        framebuffer_release(info);
}

#ifdef CONFIG_PM

static int atmel_lcdfb_suspend(struct platform_device *pdev, pm_message_t mesg)
{
        struct fb_info *info = platform_get_drvdata(pdev);
        struct atmel_lcdfb_info *sinfo = info->par;

        /*
         * We don't want to handle interrupts while the clock is
         * stopped. It may take forever.
         */
        lcdc_writel(sinfo, ATMEL_LCDC_IDR, ~0U);

        sinfo->saved_lcdcon = lcdc_readl(sinfo, ATMEL_LCDC_CONTRAST_CTR);
        lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_CTR, 0);
        atmel_lcdfb_power_control(sinfo, 0);
        atmel_lcdfb_stop(sinfo);
        atmel_lcdfb_stop_clock(sinfo);

        return 0;
}

static int atmel_lcdfb_resume(struct platform_device *pdev)
{
        struct fb_info *info = platform_get_drvdata(pdev);
        struct atmel_lcdfb_info *sinfo = info->par;

        atmel_lcdfb_start_clock(sinfo);
        atmel_lcdfb_start(sinfo);
        atmel_lcdfb_power_control(sinfo, 1);
        lcdc_writel(sinfo, ATMEL_LCDC_CONTRAST_CTR, sinfo->saved_lcdcon);

        /* Enable FIFO & DMA errors */
        lcdc_writel(sinfo, ATMEL_LCDC_IER, ATMEL_LCDC_UFLWI
                        | ATMEL_LCDC_OWRI | ATMEL_LCDC_MERI);

        return 0;
}

#else
#define atmel_lcdfb_suspend     NULL
#define atmel_lcdfb_resume      NULL
#endif

static struct platform_driver atmel_lcdfb_driver = {
        .probe          = atmel_lcdfb_probe,
        .remove         = atmel_lcdfb_remove,
        .suspend        = atmel_lcdfb_suspend,
        .resume         = atmel_lcdfb_resume,
        .driver         = {
                .name   = "atmel_lcdfb",
                .of_match_table = atmel_lcdfb_dt_ids,
        },
};
module_platform_driver(atmel_lcdfb_driver);

MODULE_DESCRIPTION("AT91 LCD Controller framebuffer driver");
MODULE_AUTHOR("Nicolas Ferre <nicolas.ferre@atmel.com>");
MODULE_LICENSE("GPL");