/*
 * Copyright (C) 2012 Texas Instruments
 * Author: Rob Clark <robdclark@gmail.com>
 *
 * 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.
 *
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_crtc.h>
#include <drm/drm_flip_work.h>
#include <drm/drm_plane_helper.h>
#include <linux/workqueue.h>
#include <linux/completion.h>
#include <linux/dma-mapping.h>
#include <linux/of_graph.h>
#include <linux/math64.h>

#include "tilcdc_drv.h"
#include "tilcdc_regs.h"

#define TILCDC_VBLANK_SAFETY_THRESHOLD_US       1000
#define TILCDC_PALETTE_SIZE                     32
#define TILCDC_PALETTE_FIRST_ENTRY              0x4000

struct tilcdc_crtc {
        struct drm_crtc base;

        struct drm_plane primary;
        const struct tilcdc_panel_info *info;
        struct drm_pending_vblank_event *event;
        struct mutex enable_lock;
        bool enabled;
        bool shutdown;
        wait_queue_head_t frame_done_wq;
        bool frame_done;
        spinlock_t irq_lock;

        unsigned int lcd_fck_rate;

        ktime_t last_vblank;
        unsigned int hvtotal_us;

        struct drm_framebuffer *next_fb;

        /* Only set if an external encoder is connected */
        bool simulate_vesa_sync;

        int sync_lost_count;
        bool frame_intact;
        struct work_struct recover_work;

        dma_addr_t palette_dma_handle;
        u16 *palette_base;
        struct completion palette_loaded;
};
#define to_tilcdc_crtc(x) container_of(x, struct tilcdc_crtc, base)

static void set_scanout(struct drm_crtc *crtc, struct drm_framebuffer *fb)
{
        struct drm_device *dev = crtc->dev;
        struct tilcdc_drm_private *priv = dev->dev_private;
        struct drm_gem_cma_object *gem;
        dma_addr_t start, end;
        u64 dma_base_and_ceiling;

        gem = drm_fb_cma_get_gem_obj(fb, 0);

        start = gem->paddr + fb->offsets[0] +
                crtc->y * fb->pitches[0] +
                crtc->x * fb->format->cpp[0];

        end = start + (crtc->mode.vdisplay * fb->pitches[0]);

        /* Write LCDC_DMA_FB_BASE_ADDR_0_REG and LCDC_DMA_FB_CEILING_ADDR_0_REG
         * with a single insruction, if available. This should make it more
         * unlikely that LCDC would fetch the DMA addresses in the middle of
         * an update.
         */
        if (priv->rev == 1)
                end -= 1;

        dma_base_and_ceiling = (u64)end << 32 | start;
        tilcdc_write64(dev, LCDC_DMA_FB_BASE_ADDR_0_REG, dma_base_and_ceiling);
}

/*
 * The driver currently only supports only true color formats. For
 * true color the palette block is bypassed, but a 32 byte palette
 * should still be loaded. The first 16-bit entry must be 0x4000 while
 * all other entries must be zeroed.
 */
static void tilcdc_crtc_load_palette(struct drm_crtc *crtc)
{
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
        struct drm_device *dev = crtc->dev;
        struct tilcdc_drm_private *priv = dev->dev_private;
        int ret;

        reinit_completion(&tilcdc_crtc->palette_loaded);

        /* Tell the LCDC where the palette is located. */
        tilcdc_write(dev, LCDC_DMA_FB_BASE_ADDR_0_REG,
                     tilcdc_crtc->palette_dma_handle);
        tilcdc_write(dev, LCDC_DMA_FB_CEILING_ADDR_0_REG,
                     (u32) tilcdc_crtc->palette_dma_handle +
                     TILCDC_PALETTE_SIZE - 1);

        /* Set dma load mode for palette loading only. */
        tilcdc_write_mask(dev, LCDC_RASTER_CTRL_REG,
                          LCDC_PALETTE_LOAD_MODE(PALETTE_ONLY),
                          LCDC_PALETTE_LOAD_MODE_MASK);

        /* Enable DMA Palette Loaded Interrupt */
        if (priv->rev == 1)
                tilcdc_set(dev, LCDC_RASTER_CTRL_REG, LCDC_V1_PL_INT_ENA);
        else
                tilcdc_write(dev, LCDC_INT_ENABLE_SET_REG, LCDC_V2_PL_INT_ENA);

        /* Enable LCDC DMA and wait for palette to be loaded. */
        tilcdc_clear_irqstatus(dev, 0xffffffff);
        tilcdc_set(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);

        ret = wait_for_completion_timeout(&tilcdc_crtc->palette_loaded,
                                          msecs_to_jiffies(50));
        if (ret == 0)
                dev_err(dev->dev, "%s: Palette loading timeout", __func__);

        /* Disable LCDC DMA and DMA Palette Loaded Interrupt. */
        tilcdc_clear(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);
        if (priv->rev == 1)
                tilcdc_clear(dev, LCDC_RASTER_CTRL_REG, LCDC_V1_PL_INT_ENA);
        else
                tilcdc_write(dev, LCDC_INT_ENABLE_CLR_REG, LCDC_V2_PL_INT_ENA);
}

static void tilcdc_crtc_enable_irqs(struct drm_device *dev)
{
        struct tilcdc_drm_private *priv = dev->dev_private;

        tilcdc_clear_irqstatus(dev, 0xffffffff);

        if (priv->rev == 1) {
                tilcdc_set(dev, LCDC_RASTER_CTRL_REG,
                        LCDC_V1_SYNC_LOST_INT_ENA | LCDC_V1_FRAME_DONE_INT_ENA |
                        LCDC_V1_UNDERFLOW_INT_ENA);
                tilcdc_set(dev, LCDC_DMA_CTRL_REG,
                        LCDC_V1_END_OF_FRAME_INT_ENA);
        } else {
                tilcdc_write(dev, LCDC_INT_ENABLE_SET_REG,
                        LCDC_V2_UNDERFLOW_INT_ENA |
                        LCDC_V2_END_OF_FRAME0_INT_ENA |
                        LCDC_FRAME_DONE | LCDC_SYNC_LOST);
        }
}

static void tilcdc_crtc_disable_irqs(struct drm_device *dev)
{
        struct tilcdc_drm_private *priv = dev->dev_private;

        /* disable irqs that we might have enabled: */
        if (priv->rev == 1) {
                tilcdc_clear(dev, LCDC_RASTER_CTRL_REG,
                        LCDC_V1_SYNC_LOST_INT_ENA | LCDC_V1_FRAME_DONE_INT_ENA |
                        LCDC_V1_UNDERFLOW_INT_ENA | LCDC_V1_PL_INT_ENA);
                tilcdc_clear(dev, LCDC_DMA_CTRL_REG,
                        LCDC_V1_END_OF_FRAME_INT_ENA);
        } else {
                tilcdc_write(dev, LCDC_INT_ENABLE_CLR_REG,
                        LCDC_V2_UNDERFLOW_INT_ENA | LCDC_V2_PL_INT_ENA |
                        LCDC_V2_END_OF_FRAME0_INT_ENA |
                        LCDC_FRAME_DONE | LCDC_SYNC_LOST);
        }
}

static void reset(struct drm_crtc *crtc)
{
        struct drm_device *dev = crtc->dev;
        struct tilcdc_drm_private *priv = dev->dev_private;

        if (priv->rev != 2)
                return;

        tilcdc_set(dev, LCDC_CLK_RESET_REG, LCDC_CLK_MAIN_RESET);
        usleep_range(250, 1000);
        tilcdc_clear(dev, LCDC_CLK_RESET_REG, LCDC_CLK_MAIN_RESET);
}

/*
 * Calculate the percentage difference between the requested pixel clock rate
 * and the effective rate resulting from calculating the clock divider value.
 */
static unsigned int tilcdc_pclk_diff(unsigned long rate,
                                     unsigned long real_rate)
{
        int r = rate / 100, rr = real_rate / 100;

        return (unsigned int)(abs(((rr - r) * 100) / r));
}

static void tilcdc_crtc_set_clk(struct drm_crtc *crtc)
{
        struct drm_device *dev = crtc->dev;
        struct tilcdc_drm_private *priv = dev->dev_private;
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
        unsigned long clk_rate, real_rate, req_rate;
        unsigned int clkdiv;
        int ret;

        clkdiv = 2; /* first try using a standard divider of 2 */

        /* mode.clock is in KHz, set_rate wants parameter in Hz */
        req_rate = crtc->mode.clock * 1000;

        ret = clk_set_rate(priv->clk, req_rate * clkdiv);
        clk_rate = clk_get_rate(priv->clk);
        if (ret < 0) {
                /*
                 * If we fail to set the clock rate (some architectures don't
                 * use the common clock framework yet and may not implement
                 * all the clk API calls for every clock), try the next best
                 * thing: adjusting the clock divider, unless clk_get_rate()
                 * failed as well.
                 */
                if (!clk_rate) {
                        /* Nothing more we can do. Just bail out. */
                        dev_err(dev->dev,
                                "failed to set the pixel clock - unable to read current lcdc clock rate\n");
                        return;
                }

                clkdiv = DIV_ROUND_CLOSEST(clk_rate, req_rate);

                /*
                 * Emit a warning if the real clock rate resulting from the
                 * calculated divider differs much from the requested rate.
                 *
                 * 5% is an arbitrary value - LCDs are usually quite tolerant
                 * about pixel clock rates.
                 */
                real_rate = clkdiv * req_rate;

                if (tilcdc_pclk_diff(clk_rate, real_rate) > 5) {
                        dev_warn(dev->dev,
                                 "effective pixel clock rate (%luHz) differs from the calculated rate (%luHz)\n",
                                 clk_rate, real_rate);
                }
        }

        tilcdc_crtc->lcd_fck_rate = clk_rate;

        DBG("lcd_clk=%u, mode clock=%d, div=%u",
            tilcdc_crtc->lcd_fck_rate, crtc->mode.clock, clkdiv);

        /* Configure the LCD clock divisor. */
        tilcdc_write(dev, LCDC_CTRL_REG, LCDC_CLK_DIVISOR(clkdiv) |
                     LCDC_RASTER_MODE);

        if (priv->rev == 2)
                tilcdc_set(dev, LCDC_CLK_ENABLE_REG,
                                LCDC_V2_DMA_CLK_EN | LCDC_V2_LIDD_CLK_EN |
                                LCDC_V2_CORE_CLK_EN);
}

static uint tilcdc_mode_hvtotal(const struct drm_display_mode *mode)
{
        return (uint) div_u64(1000llu * mode->htotal * mode->vtotal,
                              mode->clock);
}

static void tilcdc_crtc_set_mode(struct drm_crtc *crtc)
{
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
        struct drm_device *dev = crtc->dev;
        struct tilcdc_drm_private *priv = dev->dev_private;
        const struct tilcdc_panel_info *info = tilcdc_crtc->info;
        uint32_t reg, hbp, hfp, hsw, vbp, vfp, vsw;
        struct drm_display_mode *mode = &crtc->state->adjusted_mode;
        struct drm_framebuffer *fb = crtc->primary->state->fb;

        if (WARN_ON(!info))
                return;

        if (WARN_ON(!fb))
                return;

        /* Configure the Burst Size and fifo threshold of DMA: */
        reg = tilcdc_read(dev, LCDC_DMA_CTRL_REG) & ~0x00000770;
        switch (info->dma_burst_sz) {
        case 1:
                reg |= LCDC_DMA_BURST_SIZE(LCDC_DMA_BURST_1);
                break;
        case 2:
                reg |= LCDC_DMA_BURST_SIZE(LCDC_DMA_BURST_2);
                break;
        case 4:
                reg |= LCDC_DMA_BURST_SIZE(LCDC_DMA_BURST_4);
                break;
        case 8:
                reg |= LCDC_DMA_BURST_SIZE(LCDC_DMA_BURST_8);
                break;
        case 16:
                reg |= LCDC_DMA_BURST_SIZE(LCDC_DMA_BURST_16);
                break;
        default:
                dev_err(dev->dev, "invalid burst size\n");
                return;
        }
        reg |= (info->fifo_th << 8);
        tilcdc_write(dev, LCDC_DMA_CTRL_REG, reg);

        /* Configure timings: */
        hbp = mode->htotal - mode->hsync_end;
        hfp = mode->hsync_start - mode->hdisplay;
        hsw = mode->hsync_end - mode->hsync_start;
        vbp = mode->vtotal - mode->vsync_end;
        vfp = mode->vsync_start - mode->vdisplay;
        vsw = mode->vsync_end - mode->vsync_start;

        DBG("%dx%d, hbp=%u, hfp=%u, hsw=%u, vbp=%u, vfp=%u, vsw=%u",
            mode->hdisplay, mode->vdisplay, hbp, hfp, hsw, vbp, vfp, vsw);

        /* Set AC Bias Period and Number of Transitions per Interrupt: */
        reg = tilcdc_read(dev, LCDC_RASTER_TIMING_2_REG) & ~0x000fff00;
        reg |= LCDC_AC_BIAS_FREQUENCY(info->ac_bias) |
                LCDC_AC_BIAS_TRANSITIONS_PER_INT(info->ac_bias_intrpt);

        /*
         * subtract one from hfp, hbp, hsw because the hardware uses
         * a value of 0 as 1
         */
        if (priv->rev == 2) {
                /* clear bits we're going to set */
                reg &= ~0x78000033;
                reg |= ((hfp-1) & 0x300) >> 8;
                reg |= ((hbp-1) & 0x300) >> 4;
                reg |= ((hsw-1) & 0x3c0) << 21;
        }
        tilcdc_write(dev, LCDC_RASTER_TIMING_2_REG, reg);

        reg = (((mode->hdisplay >> 4) - 1) << 4) |
                (((hbp-1) & 0xff) << 24) |
                (((hfp-1) & 0xff) << 16) |
                (((hsw-1) & 0x3f) << 10);
        if (priv->rev == 2)
                reg |= (((mode->hdisplay >> 4) - 1) & 0x40) >> 3;
        tilcdc_write(dev, LCDC_RASTER_TIMING_0_REG, reg);

        reg = ((mode->vdisplay - 1) & 0x3ff) |
                ((vbp & 0xff) << 24) |
                ((vfp & 0xff) << 16) |
                (((vsw-1) & 0x3f) << 10);
        tilcdc_write(dev, LCDC_RASTER_TIMING_1_REG, reg);

        /*
         * be sure to set Bit 10 for the V2 LCDC controller,
         * otherwise limited to 1024 pixels width, stopping
         * 1920x1080 being supported.
         */
        if (priv->rev == 2) {
                if ((mode->vdisplay - 1) & 0x400) {
                        tilcdc_set(dev, LCDC_RASTER_TIMING_2_REG,
                                LCDC_LPP_B10);
                } else {
                        tilcdc_clear(dev, LCDC_RASTER_TIMING_2_REG,
                                LCDC_LPP_B10);
                }
        }

        /* Configure display type: */
        reg = tilcdc_read(dev, LCDC_RASTER_CTRL_REG) &
                ~(LCDC_TFT_MODE | LCDC_MONO_8BIT_MODE | LCDC_MONOCHROME_MODE |
                  LCDC_V2_TFT_24BPP_MODE | LCDC_V2_TFT_24BPP_UNPACK |
                  0x000ff000 /* Palette Loading Delay bits */);
        reg |= LCDC_TFT_MODE; /* no monochrome/passive support */
        if (info->tft_alt_mode)
                reg |= LCDC_TFT_ALT_ENABLE;
        if (priv->rev == 2) {
                switch (fb->format->format) {
                case DRM_FORMAT_BGR565:
                case DRM_FORMAT_RGB565:
                        break;
                case DRM_FORMAT_XBGR8888:
                case DRM_FORMAT_XRGB8888:
                        reg |= LCDC_V2_TFT_24BPP_UNPACK;
                        /* fallthrough */
                case DRM_FORMAT_BGR888:
                case DRM_FORMAT_RGB888:
                        reg |= LCDC_V2_TFT_24BPP_MODE;
                        break;
                default:
                        dev_err(dev->dev, "invalid pixel format\n");
                        return;
                }
        }
        reg |= info->fdd < 12;
        tilcdc_write(dev, LCDC_RASTER_CTRL_REG, reg);

        if (info->invert_pxl_clk)
                tilcdc_set(dev, LCDC_RASTER_TIMING_2_REG, LCDC_INVERT_PIXEL_CLOCK);
        else
                tilcdc_clear(dev, LCDC_RASTER_TIMING_2_REG, LCDC_INVERT_PIXEL_CLOCK);

        if (info->sync_ctrl)
                tilcdc_set(dev, LCDC_RASTER_TIMING_2_REG, LCDC_SYNC_CTRL);
        else
                tilcdc_clear(dev, LCDC_RASTER_TIMING_2_REG, LCDC_SYNC_CTRL);

        if (info->sync_edge)
                tilcdc_set(dev, LCDC_RASTER_TIMING_2_REG, LCDC_SYNC_EDGE);
        else
                tilcdc_clear(dev, LCDC_RASTER_TIMING_2_REG, LCDC_SYNC_EDGE);

        if (mode->flags & DRM_MODE_FLAG_NHSYNC)
                tilcdc_set(dev, LCDC_RASTER_TIMING_2_REG, LCDC_INVERT_HSYNC);
        else
                tilcdc_clear(dev, LCDC_RASTER_TIMING_2_REG, LCDC_INVERT_HSYNC);

        if (mode->flags & DRM_MODE_FLAG_NVSYNC)
                tilcdc_set(dev, LCDC_RASTER_TIMING_2_REG, LCDC_INVERT_VSYNC);
        else
                tilcdc_clear(dev, LCDC_RASTER_TIMING_2_REG, LCDC_INVERT_VSYNC);

        if (info->raster_order)
                tilcdc_set(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ORDER);
        else
                tilcdc_clear(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ORDER);

        tilcdc_crtc_set_clk(crtc);

        tilcdc_crtc_load_palette(crtc);

        set_scanout(crtc, fb);

        crtc->hwmode = crtc->state->adjusted_mode;

        tilcdc_crtc->hvtotal_us =
                tilcdc_mode_hvtotal(&crtc->hwmode);
}

static void tilcdc_crtc_enable(struct drm_crtc *crtc)
{
        struct drm_device *dev = crtc->dev;
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
        unsigned long flags;

        mutex_lock(&tilcdc_crtc->enable_lock);
        if (tilcdc_crtc->enabled || tilcdc_crtc->shutdown) {
                mutex_unlock(&tilcdc_crtc->enable_lock);
                return;
        }

        pm_runtime_get_sync(dev->dev);

        reset(crtc);

        tilcdc_crtc_set_mode(crtc);

        tilcdc_crtc_enable_irqs(dev);

        tilcdc_clear(dev, LCDC_DMA_CTRL_REG, LCDC_DUAL_FRAME_BUFFER_ENABLE);
        tilcdc_write_mask(dev, LCDC_RASTER_CTRL_REG,
                          LCDC_PALETTE_LOAD_MODE(DATA_ONLY),
                          LCDC_PALETTE_LOAD_MODE_MASK);

        /* There is no real chance for a race here as the time stamp
         * is taken before the raster DMA is started. The spin-lock is
         * taken to have a memory barrier after taking the time-stamp
         * and to avoid a context switch between taking the stamp and
         * enabling the raster.
         */
        spin_lock_irqsave(&tilcdc_crtc->irq_lock, flags);
        tilcdc_crtc->last_vblank = ktime_get();
        tilcdc_set(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);
        spin_unlock_irqrestore(&tilcdc_crtc->irq_lock, flags);

        drm_crtc_vblank_on(crtc);

        tilcdc_crtc->enabled = true;
        mutex_unlock(&tilcdc_crtc->enable_lock);
}

static void tilcdc_crtc_atomic_enable(struct drm_crtc *crtc,
                                      struct drm_crtc_state *old_state)
{
        tilcdc_crtc_enable(crtc);
}

static void tilcdc_crtc_off(struct drm_crtc *crtc, bool shutdown)
{
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
        struct drm_device *dev = crtc->dev;
        int ret;

        mutex_lock(&tilcdc_crtc->enable_lock);
        if (shutdown)
                tilcdc_crtc->shutdown = true;
        if (!tilcdc_crtc->enabled) {
                mutex_unlock(&tilcdc_crtc->enable_lock);
                return;
        }
        tilcdc_crtc->frame_done = false;
        tilcdc_clear(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);

        /*
         * Wait for framedone irq which will still come before putting
         * things to sleep..
         */
        ret = wait_event_timeout(tilcdc_crtc->frame_done_wq,
                                 tilcdc_crtc->frame_done,
                                 msecs_to_jiffies(500));
        if (ret == 0)
                dev_err(dev->dev, "%s: timeout waiting for framedone\n",
                        __func__);

        drm_crtc_vblank_off(crtc);

        tilcdc_crtc_disable_irqs(dev);

        pm_runtime_put_sync(dev->dev);

        tilcdc_crtc->enabled = false;
        mutex_unlock(&tilcdc_crtc->enable_lock);
}

static void tilcdc_crtc_disable(struct drm_crtc *crtc)
{
        tilcdc_crtc_off(crtc, false);
}

static void tilcdc_crtc_atomic_disable(struct drm_crtc *crtc,
                                       struct drm_crtc_state *old_state)
{
        tilcdc_crtc_disable(crtc);
}

void tilcdc_crtc_shutdown(struct drm_crtc *crtc)
{
        tilcdc_crtc_off(crtc, true);
}

static bool tilcdc_crtc_is_on(struct drm_crtc *crtc)
{
        return crtc->state && crtc->state->enable && crtc->state->active;
}

static void tilcdc_crtc_recover_work(struct work_struct *work)
{
        struct tilcdc_crtc *tilcdc_crtc =
                container_of(work, struct tilcdc_crtc, recover_work);
        struct drm_crtc *crtc = &tilcdc_crtc->base;

        dev_info(crtc->dev->dev, "%s: Reset CRTC", __func__);

        drm_modeset_lock(&crtc->mutex, NULL);

        if (!tilcdc_crtc_is_on(crtc))
                goto out;

        tilcdc_crtc_disable(crtc);
        tilcdc_crtc_enable(crtc);
out:
        drm_modeset_unlock(&crtc->mutex);
}

static void tilcdc_crtc_destroy(struct drm_crtc *crtc)
{
        struct tilcdc_drm_private *priv = crtc->dev->dev_private;

        tilcdc_crtc_shutdown(crtc);

        flush_workqueue(priv->wq);

        of_node_put(crtc->port);
        drm_crtc_cleanup(crtc);
}

int tilcdc_crtc_update_fb(struct drm_crtc *crtc,
                struct drm_framebuffer *fb,
                struct drm_pending_vblank_event *event)
{
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
        struct drm_device *dev = crtc->dev;

        if (tilcdc_crtc->event) {
                dev_err(dev->dev, "already pending page flip!\n");
                return -EBUSY;
        }

        tilcdc_crtc->event = event;

        mutex_lock(&tilcdc_crtc->enable_lock);

        if (tilcdc_crtc->enabled) {
                unsigned long flags;
                ktime_t next_vblank;
                s64 tdiff;

                spin_lock_irqsave(&tilcdc_crtc->irq_lock, flags);

                next_vblank = ktime_add_us(tilcdc_crtc->last_vblank,
                                           tilcdc_crtc->hvtotal_us);
                tdiff = ktime_to_us(ktime_sub(next_vblank, ktime_get()));

                if (tdiff < TILCDC_VBLANK_SAFETY_THRESHOLD_US)
                        tilcdc_crtc->next_fb = fb;
                else
                        set_scanout(crtc, fb);

                spin_unlock_irqrestore(&tilcdc_crtc->irq_lock, flags);
        }

        mutex_unlock(&tilcdc_crtc->enable_lock);

        return 0;
}

static bool tilcdc_crtc_mode_fixup(struct drm_crtc *crtc,
                const struct drm_display_mode *mode,
                struct drm_display_mode *adjusted_mode)
{
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);

        if (!tilcdc_crtc->simulate_vesa_sync)
                return true;

        /*
         * tilcdc does not generate VESA-compliant sync but aligns
         * VS on the second edge of HS instead of first edge.
         * We use adjusted_mode, to fixup sync by aligning both rising
         * edges and add HSKEW offset to fix the sync.
         */
        adjusted_mode->hskew = mode->hsync_end - mode->hsync_start;
        adjusted_mode->flags |= DRM_MODE_FLAG_HSKEW;

        if (mode->flags & DRM_MODE_FLAG_NHSYNC) {
                adjusted_mode->flags |= DRM_MODE_FLAG_PHSYNC;
                adjusted_mode->flags &= ~DRM_MODE_FLAG_NHSYNC;
        } else {
                adjusted_mode->flags |= DRM_MODE_FLAG_NHSYNC;
                adjusted_mode->flags &= ~DRM_MODE_FLAG_PHSYNC;
        }

        return true;
}

static int tilcdc_crtc_atomic_check(struct drm_crtc *crtc,
                                    struct drm_crtc_state *state)
{
        struct drm_display_mode *mode = &state->mode;
        int ret;

        /* If we are not active we don't care */
        if (!state->active)
                return 0;

        if (state->state->planes[0].ptr != crtc->primary ||
            state->state->planes[0].state == NULL ||
            state->state->planes[0].state->crtc != crtc) {
                dev_dbg(crtc->dev->dev, "CRTC primary plane must be present");
                return -EINVAL;
        }

        ret = tilcdc_crtc_mode_valid(crtc, mode);
        if (ret) {
                dev_dbg(crtc->dev->dev, "Mode \"%s\" not valid", mode->name);
                return -EINVAL;
        }

        return 0;
}

static int tilcdc_crtc_enable_vblank(struct drm_crtc *crtc)
{
        return 0;
}

static void tilcdc_crtc_disable_vblank(struct drm_crtc *crtc)
{
}

static void tilcdc_crtc_reset(struct drm_crtc *crtc)
{
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
        struct drm_device *dev = crtc->dev;
        int ret;

        drm_atomic_helper_crtc_reset(crtc);

        /* Turn the raster off if it for some reason is on. */
        pm_runtime_get_sync(dev->dev);
        if (tilcdc_read(dev, LCDC_RASTER_CTRL_REG) & LCDC_RASTER_ENABLE) {
                /* Enable DMA Frame Done Interrupt */
                tilcdc_write(dev, LCDC_INT_ENABLE_SET_REG, LCDC_FRAME_DONE);
                tilcdc_clear_irqstatus(dev, 0xffffffff);

                tilcdc_crtc->frame_done = false;
                tilcdc_clear(dev, LCDC_RASTER_CTRL_REG, LCDC_RASTER_ENABLE);

                ret = wait_event_timeout(tilcdc_crtc->frame_done_wq,
                                         tilcdc_crtc->frame_done,
                                         msecs_to_jiffies(500));
                if (ret == 0)
                        dev_err(dev->dev, "%s: timeout waiting for framedone\n",
                                __func__);
        }
        pm_runtime_put_sync(dev->dev);
}

static const struct drm_crtc_funcs tilcdc_crtc_funcs = {
        .destroy        = tilcdc_crtc_destroy,
        .set_config     = drm_atomic_helper_set_config,
        .page_flip      = drm_atomic_helper_page_flip,
        .reset          = tilcdc_crtc_reset,
        .atomic_duplicate_state = drm_atomic_helper_crtc_duplicate_state,
        .atomic_destroy_state = drm_atomic_helper_crtc_destroy_state,
        .enable_vblank  = tilcdc_crtc_enable_vblank,
        .disable_vblank = tilcdc_crtc_disable_vblank,
};

static const struct drm_crtc_helper_funcs tilcdc_crtc_helper_funcs = {
                .mode_fixup     = tilcdc_crtc_mode_fixup,
                .atomic_check   = tilcdc_crtc_atomic_check,
                .atomic_enable  = tilcdc_crtc_atomic_enable,
                .atomic_disable = tilcdc_crtc_atomic_disable,
};

int tilcdc_crtc_max_width(struct drm_crtc *crtc)
{
        struct drm_device *dev = crtc->dev;
        struct tilcdc_drm_private *priv = dev->dev_private;
        int max_width = 0;

        if (priv->rev == 1)
                max_width = 1024;
        else if (priv->rev == 2)
                max_width = 2048;

        return max_width;
}

int tilcdc_crtc_mode_valid(struct drm_crtc *crtc, struct drm_display_mode *mode)
{
        struct tilcdc_drm_private *priv = crtc->dev->dev_private;
        unsigned int bandwidth;
        uint32_t hbp, hfp, hsw, vbp, vfp, vsw;

        /*
         * check to see if the width is within the range that
         * the LCD Controller physically supports
         */
        if (mode->hdisplay > tilcdc_crtc_max_width(crtc))
                return MODE_VIRTUAL_X;

        /* width must be multiple of 16 */
        if (mode->hdisplay & 0xf)
                return MODE_VIRTUAL_X;

        if (mode->vdisplay > 2048)
                return MODE_VIRTUAL_Y;

        DBG("Processing mode %dx%d@%d with pixel clock %d",
                mode->hdisplay, mode->vdisplay,
                drm_mode_vrefresh(mode), mode->clock);

        hbp = mode->htotal - mode->hsync_end;
        hfp = mode->hsync_start - mode->hdisplay;
        hsw = mode->hsync_end - mode->hsync_start;
        vbp = mode->vtotal - mode->vsync_end;
        vfp = mode->vsync_start - mode->vdisplay;
        vsw = mode->vsync_end - mode->vsync_start;

        if ((hbp-1) & ~0x3ff) {
                DBG("Pruning mode: Horizontal Back Porch out of range");
                return MODE_HBLANK_WIDE;
        }

        if ((hfp-1) & ~0x3ff) {
                DBG("Pruning mode: Horizontal Front Porch out of range");
                return MODE_HBLANK_WIDE;
        }

        if ((hsw-1) & ~0x3ff) {
                DBG("Pruning mode: Horizontal Sync Width out of range");
                return MODE_HSYNC_WIDE;
        }

        if (vbp & ~0xff) {
                DBG("Pruning mode: Vertical Back Porch out of range");
                return MODE_VBLANK_WIDE;
        }

        if (vfp & ~0xff) {
                DBG("Pruning mode: Vertical Front Porch out of range");
                return MODE_VBLANK_WIDE;
        }

        if ((vsw-1) & ~0x3f) {
                DBG("Pruning mode: Vertical Sync Width out of range");
                return MODE_VSYNC_WIDE;
        }

        /*
         * some devices have a maximum allowed pixel clock
         * configured from the DT
         */
        if (mode->clock > priv->max_pixelclock) {
                DBG("Pruning mode: pixel clock too high");
                return MODE_CLOCK_HIGH;
        }

        /*
         * some devices further limit the max horizontal resolution
         * configured from the DT
         */
        if (mode->hdisplay > priv->max_width)
                return MODE_BAD_WIDTH;

        /* filter out modes that would require too much memory bandwidth: */
        bandwidth = mode->hdisplay * mode->vdisplay *
                drm_mode_vrefresh(mode);
        if (bandwidth > priv->max_bandwidth) {
                DBG("Pruning mode: exceeds defined bandwidth limit");
                return MODE_BAD;
        }

        return MODE_OK;
}

void tilcdc_crtc_set_panel_info(struct drm_crtc *crtc,
                const struct tilcdc_panel_info *info)
{
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
        tilcdc_crtc->info = info;
}

void tilcdc_crtc_set_simulate_vesa_sync(struct drm_crtc *crtc,
                                        bool simulate_vesa_sync)
{
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);

        tilcdc_crtc->simulate_vesa_sync = simulate_vesa_sync;
}

void tilcdc_crtc_update_clk(struct drm_crtc *crtc)
{
        struct drm_device *dev = crtc->dev;
        struct tilcdc_drm_private *priv = dev->dev_private;
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);

        drm_modeset_lock(&crtc->mutex, NULL);
        if (tilcdc_crtc->lcd_fck_rate != clk_get_rate(priv->clk)) {
                if (tilcdc_crtc_is_on(crtc)) {
                        pm_runtime_get_sync(dev->dev);
                        tilcdc_crtc_disable(crtc);

                        tilcdc_crtc_set_clk(crtc);

                        tilcdc_crtc_enable(crtc);
                        pm_runtime_put_sync(dev->dev);
                }
        }
        drm_modeset_unlock(&crtc->mutex);
}

#define SYNC_LOST_COUNT_LIMIT 50

irqreturn_t tilcdc_crtc_irq(struct drm_crtc *crtc)
{
        struct tilcdc_crtc *tilcdc_crtc = to_tilcdc_crtc(crtc);
        struct drm_device *dev = crtc->dev;
        struct tilcdc_drm_private *priv = dev->dev_private;
        uint32_t stat, reg;

        stat = tilcdc_read_irqstatus(dev);
        tilcdc_clear_irqstatus(dev, stat);

        if (stat & LCDC_END_OF_FRAME0) {
                unsigned long flags;
                bool skip_event = false;
                ktime_t now;

                now = ktime_get();

                spin_lock_irqsave(&tilcdc_crtc->irq_lock, flags);

                tilcdc_crtc->last_vblank = now;

                if (tilcdc_crtc->next_fb) {
                        set_scanout(crtc, tilcdc_crtc->next_fb);
                        tilcdc_crtc->next_fb = NULL;
                        skip_event = true;
                }

                spin_unlock_irqrestore(&tilcdc_crtc->irq_lock, flags);

                drm_crtc_handle_vblank(crtc);

                if (!skip_event) {
                        struct drm_pending_vblank_event *event;

                        spin_lock_irqsave(&dev->event_lock, flags);

                        event = tilcdc_crtc->event;
                        tilcdc_crtc->event = NULL;
                        if (event)
                                drm_crtc_send_vblank_event(crtc, event);

                        spin_unlock_irqrestore(&dev->event_lock, flags);
                }

                if (tilcdc_crtc->frame_intact)
                        tilcdc_crtc->sync_lost_count = 0;
                else
                        tilcdc_crtc->frame_intact = true;
        }

        if (stat & LCDC_FIFO_UNDERFLOW)
                dev_err_ratelimited(dev->dev, "%s(0x%08x): FIFO underflow",
                                    __func__, stat);

        if (stat & LCDC_PL_LOAD_DONE) {
                complete(&tilcdc_crtc->palette_loaded);
                if (priv->rev == 1)
                        tilcdc_clear(dev, LCDC_RASTER_CTRL_REG,
                                     LCDC_V1_PL_INT_ENA);
                else
                        tilcdc_write(dev, LCDC_INT_ENABLE_CLR_REG,
                                     LCDC_V2_PL_INT_ENA);
        }

        if (stat & LCDC_SYNC_LOST) {
                dev_err_ratelimited(dev->dev, "%s(0x%08x): Sync lost",
                                    __func__, stat);
                tilcdc_crtc->frame_intact = false;
                if (priv->rev == 1) {
                        reg = tilcdc_read(dev, LCDC_RASTER_CTRL_REG);
                        if (reg & LCDC_RASTER_ENABLE) {
                                tilcdc_clear(dev, LCDC_RASTER_CTRL_REG,
                                             LCDC_RASTER_ENABLE);
                                tilcdc_set(dev, LCDC_RASTER_CTRL_REG,
                                           LCDC_RASTER_ENABLE);
                        }
                } else {
                        if (tilcdc_crtc->sync_lost_count++ >
                            SYNC_LOST_COUNT_LIMIT) {
                                dev_err(dev->dev,
                                        "%s(0x%08x): Sync lost flood detected, recovering",
                                        __func__, stat);
                                queue_work(system_wq,
                                           &tilcdc_crtc->recover_work);
                                tilcdc_write(dev, LCDC_INT_ENABLE_CLR_REG,
                                             LCDC_SYNC_LOST);
                                tilcdc_crtc->sync_lost_count = 0;
                        }
                }
        }

        if (stat & LCDC_FRAME_DONE) {
                tilcdc_crtc->frame_done = true;
                wake_up(&tilcdc_crtc->frame_done_wq);
                /* rev 1 lcdc appears to hang if irq is not disbaled here */
                if (priv->rev == 1)
                        tilcdc_clear(dev, LCDC_RASTER_CTRL_REG,
                                     LCDC_V1_FRAME_DONE_INT_ENA);
        }

        /* For revision 2 only */
        if (priv->rev == 2) {
                /* Indicate to LCDC that the interrupt service routine has
                 * completed, see 13.3.6.1.6 in AM335x TRM.
                 */
                tilcdc_write(dev, LCDC_END_OF_INT_IND_REG, 0);
        }

        return IRQ_HANDLED;
}

int tilcdc_crtc_create(struct drm_device *dev)
{
        struct tilcdc_drm_private *priv = dev->dev_private;
        struct tilcdc_crtc *tilcdc_crtc;
        struct drm_crtc *crtc;
        int ret;

        tilcdc_crtc = devm_kzalloc(dev->dev, sizeof(*tilcdc_crtc), GFP_KERNEL);
        if (!tilcdc_crtc)
                return -ENOMEM;

        init_completion(&tilcdc_crtc->palette_loaded);

        tilcdc_crtc->palette_base = dmam_alloc_coherent(dev->dev,
                                        TILCDC_PALETTE_SIZE,
                                        &tilcdc_crtc->palette_dma_handle,
                                        GFP_KERNEL | __GFP_ZERO);
        if (!tilcdc_crtc->palette_base)
                return -ENOMEM;
        *tilcdc_crtc->palette_base = TILCDC_PALETTE_FIRST_ENTRY;

        crtc = &tilcdc_crtc->base;

        ret = tilcdc_plane_init(dev, &tilcdc_crtc->primary);
        if (ret < 0)
                goto fail;

        mutex_init(&tilcdc_crtc->enable_lock);

        init_waitqueue_head(&tilcdc_crtc->frame_done_wq);

        spin_lock_init(&tilcdc_crtc->irq_lock);
        INIT_WORK(&tilcdc_crtc->recover_work, tilcdc_crtc_recover_work);

        ret = drm_crtc_init_with_planes(dev, crtc,
                                        &tilcdc_crtc->primary,
                                        NULL,
                                        &tilcdc_crtc_funcs,
                                        "tilcdc crtc");
        if (ret < 0)
                goto fail;

        drm_crtc_helper_add(crtc, &tilcdc_crtc_helper_funcs);

        if (priv->is_componentized) {
                crtc->port = of_graph_get_port_by_id(dev->dev->of_node, 0);
                if (!crtc->port) { /* This should never happen */
                        dev_err(dev->dev, "Port node not found in %pOF\n",
                                dev->dev->of_node);
                        ret = -EINVAL;
                        goto fail;
                }
        }

        priv->crtc = crtc;
        return 0;

fail:
        tilcdc_crtc_destroy(crtc);
        return ret;
}