/*
 * Copyright (C) 2015 Broadcom
 *
 * 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.
 */

/**
 * DOC: VC4 plane module
 *
 * Each DRM plane is a layer of pixels being scanned out by the HVS.
 *
 * At atomic modeset check time, we compute the HVS display element
 * state that would be necessary for displaying the plane (giving us a
 * chance to figure out if a plane configuration is invalid), then at
 * atomic flush time the CRTC will ask us to write our element state
 * into the region of the HVS that it has allocated for us.
 */

#include "vc4_drv.h"
#include "vc4_regs.h"
#include "drm_atomic_helper.h"
#include "drm_fb_cma_helper.h"
#include "drm_plane_helper.h"

enum vc4_scaling_mode {
        VC4_SCALING_NONE,
        VC4_SCALING_TPZ,
        VC4_SCALING_PPF,
};

struct vc4_plane_state {
        struct drm_plane_state base;
        /* System memory copy of the display list for this element, computed
         * at atomic_check time.
         */
        u32 *dlist;
        u32 dlist_size; /* Number of dwords allocated for the display list */
        u32 dlist_count; /* Number of used dwords in the display list. */

        /* Offset in the dlist to various words, for pageflip or
         * cursor updates.
         */
        u32 pos0_offset;
        u32 pos2_offset;
        u32 ptr0_offset;

        /* Offset where the plane's dlist was last stored in the
         * hardware at vc4_crtc_atomic_flush() time.
         */
        u32 __iomem *hw_dlist;

        /* Clipped coordinates of the plane on the display. */
        int crtc_x, crtc_y, crtc_w, crtc_h;
        /* Clipped area being scanned from in the FB. */
        u32 src_x, src_y;

        u32 src_w[2], src_h[2];

        /* Scaling selection for the RGB/Y plane and the Cb/Cr planes. */
        enum vc4_scaling_mode x_scaling[2], y_scaling[2];
        bool is_unity;
        bool is_yuv;

        /* Offset to start scanning out from the start of the plane's
         * BO.
         */
        u32 offsets[3];

        /* Our allocation in LBM for temporary storage during scaling. */
        struct drm_mm_node lbm;
};

static inline struct vc4_plane_state *
to_vc4_plane_state(struct drm_plane_state *state)
{
        return (struct vc4_plane_state *)state;
}

static const struct hvs_format {
        u32 drm; /* DRM_FORMAT_* */
        u32 hvs; /* HVS_FORMAT_* */
        u32 pixel_order;
        bool has_alpha;
        bool flip_cbcr;
} hvs_formats[] = {
        {
                .drm = DRM_FORMAT_XRGB8888, .hvs = HVS_PIXEL_FORMAT_RGBA8888,
                .pixel_order = HVS_PIXEL_ORDER_ABGR, .has_alpha = false,
        },
        {
                .drm = DRM_FORMAT_ARGB8888, .hvs = HVS_PIXEL_FORMAT_RGBA8888,
                .pixel_order = HVS_PIXEL_ORDER_ABGR, .has_alpha = true,
        },
        {
                .drm = DRM_FORMAT_ABGR8888, .hvs = HVS_PIXEL_FORMAT_RGBA8888,
                .pixel_order = HVS_PIXEL_ORDER_ARGB, .has_alpha = true,
        },
        {
                .drm = DRM_FORMAT_XBGR8888, .hvs = HVS_PIXEL_FORMAT_RGBA8888,
                .pixel_order = HVS_PIXEL_ORDER_ARGB, .has_alpha = false,
        },
        {
                .drm = DRM_FORMAT_RGB565, .hvs = HVS_PIXEL_FORMAT_RGB565,
                .pixel_order = HVS_PIXEL_ORDER_XRGB, .has_alpha = false,
        },
        {
                .drm = DRM_FORMAT_BGR565, .hvs = HVS_PIXEL_FORMAT_RGB565,
                .pixel_order = HVS_PIXEL_ORDER_XBGR, .has_alpha = false,
        },
        {
                .drm = DRM_FORMAT_ARGB1555, .hvs = HVS_PIXEL_FORMAT_RGBA5551,
                .pixel_order = HVS_PIXEL_ORDER_ABGR, .has_alpha = true,
        },
        {
                .drm = DRM_FORMAT_XRGB1555, .hvs = HVS_PIXEL_FORMAT_RGBA5551,
                .pixel_order = HVS_PIXEL_ORDER_ABGR, .has_alpha = false,
        },
        {
                .drm = DRM_FORMAT_YUV422,
                .hvs = HVS_PIXEL_FORMAT_YCBCR_YUV422_3PLANE,
        },
        {
                .drm = DRM_FORMAT_YVU422,
                .hvs = HVS_PIXEL_FORMAT_YCBCR_YUV422_3PLANE,
                .flip_cbcr = true,
        },
        {
                .drm = DRM_FORMAT_YUV420,
                .hvs = HVS_PIXEL_FORMAT_YCBCR_YUV420_3PLANE,
        },
        {
                .drm = DRM_FORMAT_YVU420,
                .hvs = HVS_PIXEL_FORMAT_YCBCR_YUV420_3PLANE,
                .flip_cbcr = true,
        },
        {
                .drm = DRM_FORMAT_NV12,
                .hvs = HVS_PIXEL_FORMAT_YCBCR_YUV420_2PLANE,
        },
        {
                .drm = DRM_FORMAT_NV16,
                .hvs = HVS_PIXEL_FORMAT_YCBCR_YUV422_2PLANE,
        },
};

static const struct hvs_format *vc4_get_hvs_format(u32 drm_format)
{
        unsigned i;

        for (i = 0; i < ARRAY_SIZE(hvs_formats); i++) {
                if (hvs_formats[i].drm == drm_format)
                        return &hvs_formats[i];
        }

        return NULL;
}

static enum vc4_scaling_mode vc4_get_scaling_mode(u32 src, u32 dst)
{
        if (dst > src)
                return VC4_SCALING_PPF;
        else if (dst < src)
                return VC4_SCALING_TPZ;
        else
                return VC4_SCALING_NONE;
}

static bool plane_enabled(struct drm_plane_state *state)
{
        return state->fb && state->crtc;
}

static struct drm_plane_state *vc4_plane_duplicate_state(struct drm_plane *plane)
{
        struct vc4_plane_state *vc4_state;

        if (WARN_ON(!plane->state))
                return NULL;

        vc4_state = kmemdup(plane->state, sizeof(*vc4_state), GFP_KERNEL);
        if (!vc4_state)
                return NULL;

        memset(&vc4_state->lbm, 0, sizeof(vc4_state->lbm));

        __drm_atomic_helper_plane_duplicate_state(plane, &vc4_state->base);

        if (vc4_state->dlist) {
                vc4_state->dlist = kmemdup(vc4_state->dlist,
                                           vc4_state->dlist_count * 4,
                                           GFP_KERNEL);
                if (!vc4_state->dlist) {
                        kfree(vc4_state);
                        return NULL;
                }
                vc4_state->dlist_size = vc4_state->dlist_count;
        }

        return &vc4_state->base;
}

static void vc4_plane_destroy_state(struct drm_plane *plane,
                                    struct drm_plane_state *state)
{
        struct vc4_dev *vc4 = to_vc4_dev(plane->dev);
        struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);

        if (vc4_state->lbm.allocated) {
                unsigned long irqflags;

                spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
                drm_mm_remove_node(&vc4_state->lbm);
                spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
        }

        kfree(vc4_state->dlist);
        __drm_atomic_helper_plane_destroy_state(&vc4_state->base);
        kfree(state);
}

/* Called during init to allocate the plane's atomic state. */
static void vc4_plane_reset(struct drm_plane *plane)
{
        struct vc4_plane_state *vc4_state;

        WARN_ON(plane->state);

        vc4_state = kzalloc(sizeof(*vc4_state), GFP_KERNEL);
        if (!vc4_state)
                return;

        plane->state = &vc4_state->base;
        vc4_state->base.plane = plane;
}

static void vc4_dlist_write(struct vc4_plane_state *vc4_state, u32 val)
{
        if (vc4_state->dlist_count == vc4_state->dlist_size) {
                u32 new_size = max(4u, vc4_state->dlist_count * 2);
                u32 *new_dlist = kmalloc(new_size * 4, GFP_KERNEL);

                if (!new_dlist)
                        return;
                memcpy(new_dlist, vc4_state->dlist, vc4_state->dlist_count * 4);

                kfree(vc4_state->dlist);
                vc4_state->dlist = new_dlist;
                vc4_state->dlist_size = new_size;
        }

        vc4_state->dlist[vc4_state->dlist_count++] = val;
}

/* Returns the scl0/scl1 field based on whether the dimensions need to
 * be up/down/non-scaled.
 *
 * This is a replication of a table from the spec.
 */
static u32 vc4_get_scl_field(struct drm_plane_state *state, int plane)
{
        struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);

        switch (vc4_state->x_scaling[plane] << 2 | vc4_state->y_scaling[plane]) {
        case VC4_SCALING_PPF << 2 | VC4_SCALING_PPF:
                return SCALER_CTL0_SCL_H_PPF_V_PPF;
        case VC4_SCALING_TPZ << 2 | VC4_SCALING_PPF:
                return SCALER_CTL0_SCL_H_TPZ_V_PPF;
        case VC4_SCALING_PPF << 2 | VC4_SCALING_TPZ:
                return SCALER_CTL0_SCL_H_PPF_V_TPZ;
        case VC4_SCALING_TPZ << 2 | VC4_SCALING_TPZ:
                return SCALER_CTL0_SCL_H_TPZ_V_TPZ;
        case VC4_SCALING_PPF << 2 | VC4_SCALING_NONE:
                return SCALER_CTL0_SCL_H_PPF_V_NONE;
        case VC4_SCALING_NONE << 2 | VC4_SCALING_PPF:
                return SCALER_CTL0_SCL_H_NONE_V_PPF;
        case VC4_SCALING_NONE << 2 | VC4_SCALING_TPZ:
                return SCALER_CTL0_SCL_H_NONE_V_TPZ;
        case VC4_SCALING_TPZ << 2 | VC4_SCALING_NONE:
                return SCALER_CTL0_SCL_H_TPZ_V_NONE;
        default:
        case VC4_SCALING_NONE << 2 | VC4_SCALING_NONE:
                /* The unity case is independently handled by
                 * SCALER_CTL0_UNITY.
                 */
                return 0;
        }
}

static int vc4_plane_setup_clipping_and_scaling(struct drm_plane_state *state)
{
        struct drm_plane *plane = state->plane;
        struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
        struct drm_framebuffer *fb = state->fb;
        struct drm_gem_cma_object *bo = drm_fb_cma_get_gem_obj(fb, 0);
        u32 subpixel_src_mask = (1 << 16) - 1;
        u32 format = fb->pixel_format;
        int num_planes = drm_format_num_planes(format);
        u32 h_subsample = 1;
        u32 v_subsample = 1;
        int i;

        for (i = 0; i < num_planes; i++)
                vc4_state->offsets[i] = bo->paddr + fb->offsets[i];

        /* We don't support subpixel source positioning for scaling. */
        if ((state->src_x & subpixel_src_mask) ||
            (state->src_y & subpixel_src_mask) ||
            (state->src_w & subpixel_src_mask) ||
            (state->src_h & subpixel_src_mask)) {
                return -EINVAL;
        }

        vc4_state->src_x = state->src_x >> 16;
        vc4_state->src_y = state->src_y >> 16;
        vc4_state->src_w[0] = state->src_w >> 16;
        vc4_state->src_h[0] = state->src_h >> 16;

        vc4_state->crtc_x = state->crtc_x;
        vc4_state->crtc_y = state->crtc_y;
        vc4_state->crtc_w = state->crtc_w;
        vc4_state->crtc_h = state->crtc_h;

        vc4_state->x_scaling[0] = vc4_get_scaling_mode(vc4_state->src_w[0],
                                                       vc4_state->crtc_w);
        vc4_state->y_scaling[0] = vc4_get_scaling_mode(vc4_state->src_h[0],
                                                       vc4_state->crtc_h);

        if (num_planes > 1) {
                vc4_state->is_yuv = true;

                h_subsample = drm_format_horz_chroma_subsampling(format);
                v_subsample = drm_format_vert_chroma_subsampling(format);
                vc4_state->src_w[1] = vc4_state->src_w[0] / h_subsample;
                vc4_state->src_h[1] = vc4_state->src_h[0] / v_subsample;

                vc4_state->x_scaling[1] =
                        vc4_get_scaling_mode(vc4_state->src_w[1],
                                             vc4_state->crtc_w);
                vc4_state->y_scaling[1] =
                        vc4_get_scaling_mode(vc4_state->src_h[1],
                                             vc4_state->crtc_h);

                /* YUV conversion requires that scaling be enabled,
                 * even on a plane that's otherwise 1:1.  Choose TPZ
                 * for simplicity.
                 */
                if (vc4_state->x_scaling[0] == VC4_SCALING_NONE)
                        vc4_state->x_scaling[0] = VC4_SCALING_TPZ;
                if (vc4_state->y_scaling[0] == VC4_SCALING_NONE)
                        vc4_state->y_scaling[0] = VC4_SCALING_TPZ;
        }

        vc4_state->is_unity = (vc4_state->x_scaling[0] == VC4_SCALING_NONE &&
                               vc4_state->y_scaling[0] == VC4_SCALING_NONE &&
                               vc4_state->x_scaling[1] == VC4_SCALING_NONE &&
                               vc4_state->y_scaling[1] == VC4_SCALING_NONE);

        /* No configuring scaling on the cursor plane, since it gets
           non-vblank-synced updates, and scaling requires requires
           LBM changes which have to be vblank-synced.
         */
        if (plane->type == DRM_PLANE_TYPE_CURSOR && !vc4_state->is_unity)
                return -EINVAL;

        /* Clamp the on-screen start x/y to 0.  The hardware doesn't
         * support negative y, and negative x wastes bandwidth.
         */
        if (vc4_state->crtc_x < 0) {
                for (i = 0; i < num_planes; i++) {
                        u32 cpp = drm_format_plane_cpp(fb->pixel_format, i);
                        u32 subs = ((i == 0) ? 1 : h_subsample);

                        vc4_state->offsets[i] += (cpp *
                                                  (-vc4_state->crtc_x) / subs);
                }
                vc4_state->src_w[0] += vc4_state->crtc_x;
                vc4_state->src_w[1] += vc4_state->crtc_x / h_subsample;
                vc4_state->crtc_x = 0;
        }

        if (vc4_state->crtc_y < 0) {
                for (i = 0; i < num_planes; i++) {
                        u32 subs = ((i == 0) ? 1 : v_subsample);

                        vc4_state->offsets[i] += (fb->pitches[i] *
                                                  (-vc4_state->crtc_y) / subs);
                }
                vc4_state->src_h[0] += vc4_state->crtc_y;
                vc4_state->src_h[1] += vc4_state->crtc_y / v_subsample;
                vc4_state->crtc_y = 0;
        }

        return 0;
}

static void vc4_write_tpz(struct vc4_plane_state *vc4_state, u32 src, u32 dst)
{
        u32 scale, recip;

        scale = (1 << 16) * src / dst;

        /* The specs note that while the reciprocal would be defined
         * as (1<<32)/scale, ~0 is close enough.
         */
        recip = ~0 / scale;

        vc4_dlist_write(vc4_state,
                        VC4_SET_FIELD(scale, SCALER_TPZ0_SCALE) |
                        VC4_SET_FIELD(0, SCALER_TPZ0_IPHASE));
        vc4_dlist_write(vc4_state,
                        VC4_SET_FIELD(recip, SCALER_TPZ1_RECIP));
}

static void vc4_write_ppf(struct vc4_plane_state *vc4_state, u32 src, u32 dst)
{
        u32 scale = (1 << 16) * src / dst;

        vc4_dlist_write(vc4_state,
                        SCALER_PPF_AGC |
                        VC4_SET_FIELD(scale, SCALER_PPF_SCALE) |
                        VC4_SET_FIELD(0, SCALER_PPF_IPHASE));
}

static u32 vc4_lbm_size(struct drm_plane_state *state)
{
        struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
        /* This is the worst case number.  One of the two sizes will
         * be used depending on the scaling configuration.
         */
        u32 pix_per_line = max(vc4_state->src_w[0], (u32)vc4_state->crtc_w);
        u32 lbm;

        if (!vc4_state->is_yuv) {
                if (vc4_state->is_unity)
                        return 0;
                else if (vc4_state->y_scaling[0] == VC4_SCALING_TPZ)
                        lbm = pix_per_line * 8;
                else {
                        /* In special cases, this multiplier might be 12. */
                        lbm = pix_per_line * 16;
                }
        } else {
                /* There are cases for this going down to a multiplier
                 * of 2, but according to the firmware source, the
                 * table in the docs is somewhat wrong.
                 */
                lbm = pix_per_line * 16;
        }

        lbm = roundup(lbm, 32);

        return lbm;
}

static void vc4_write_scaling_parameters(struct drm_plane_state *state,
                                         int channel)
{
        struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);

        /* Ch0 H-PPF Word 0: Scaling Parameters */
        if (vc4_state->x_scaling[channel] == VC4_SCALING_PPF) {
                vc4_write_ppf(vc4_state,
                              vc4_state->src_w[channel], vc4_state->crtc_w);
        }

        /* Ch0 V-PPF Words 0-1: Scaling Parameters, Context */
        if (vc4_state->y_scaling[channel] == VC4_SCALING_PPF) {
                vc4_write_ppf(vc4_state,
                              vc4_state->src_h[channel], vc4_state->crtc_h);
                vc4_dlist_write(vc4_state, 0xc0c0c0c0);
        }

        /* Ch0 H-TPZ Words 0-1: Scaling Parameters, Recip */
        if (vc4_state->x_scaling[channel] == VC4_SCALING_TPZ) {
                vc4_write_tpz(vc4_state,
                              vc4_state->src_w[channel], vc4_state->crtc_w);
        }

        /* Ch0 V-TPZ Words 0-2: Scaling Parameters, Recip, Context */
        if (vc4_state->y_scaling[channel] == VC4_SCALING_TPZ) {
                vc4_write_tpz(vc4_state,
                              vc4_state->src_h[channel], vc4_state->crtc_h);
                vc4_dlist_write(vc4_state, 0xc0c0c0c0);
        }
}

/* Writes out a full display list for an active plane to the plane's
 * private dlist state.
 */
static int vc4_plane_mode_set(struct drm_plane *plane,
                              struct drm_plane_state *state)
{
        struct vc4_dev *vc4 = to_vc4_dev(plane->dev);
        struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);
        struct drm_framebuffer *fb = state->fb;
        u32 ctl0_offset = vc4_state->dlist_count;
        const struct hvs_format *format = vc4_get_hvs_format(fb->pixel_format);
        int num_planes = drm_format_num_planes(format->drm);
        u32 scl0, scl1;
        u32 lbm_size;
        unsigned long irqflags;
        int ret, i;

        ret = vc4_plane_setup_clipping_and_scaling(state);
        if (ret)
                return ret;

        /* Allocate the LBM memory that the HVS will use for temporary
         * storage due to our scaling/format conversion.
         */
        lbm_size = vc4_lbm_size(state);
        if (lbm_size) {
                if (!vc4_state->lbm.allocated) {
                        spin_lock_irqsave(&vc4->hvs->mm_lock, irqflags);
                        ret = drm_mm_insert_node(&vc4->hvs->lbm_mm,
                                                 &vc4_state->lbm,
                                                 lbm_size, 32, 0);
                        spin_unlock_irqrestore(&vc4->hvs->mm_lock, irqflags);
                } else {
                        WARN_ON_ONCE(lbm_size != vc4_state->lbm.size);
                }
        }

        if (ret)
                return ret;

        /* SCL1 is used for Cb/Cr scaling of planar formats.  For RGB
         * and 4:4:4, scl1 should be set to scl0 so both channels of
         * the scaler do the same thing.  For YUV, the Y plane needs
         * to be put in channel 1 and Cb/Cr in channel 0, so we swap
         * the scl fields here.
         */
        if (num_planes == 1) {
                scl0 = vc4_get_scl_field(state, 1);
                scl1 = scl0;
        } else {
                scl0 = vc4_get_scl_field(state, 1);
                scl1 = vc4_get_scl_field(state, 0);
        }

        /* Control word */
        vc4_dlist_write(vc4_state,
                        SCALER_CTL0_VALID |
                        (format->pixel_order << SCALER_CTL0_ORDER_SHIFT) |
                        (format->hvs << SCALER_CTL0_PIXEL_FORMAT_SHIFT) |
                        (vc4_state->is_unity ? SCALER_CTL0_UNITY : 0) |
                        VC4_SET_FIELD(scl0, SCALER_CTL0_SCL0) |
                        VC4_SET_FIELD(scl1, SCALER_CTL0_SCL1));

        /* Position Word 0: Image Positions and Alpha Value */
        vc4_state->pos0_offset = vc4_state->dlist_count;
        vc4_dlist_write(vc4_state,
                        VC4_SET_FIELD(0xff, SCALER_POS0_FIXED_ALPHA) |
                        VC4_SET_FIELD(vc4_state->crtc_x, SCALER_POS0_START_X) |
                        VC4_SET_FIELD(vc4_state->crtc_y, SCALER_POS0_START_Y));

        /* Position Word 1: Scaled Image Dimensions. */
        if (!vc4_state->is_unity) {
                vc4_dlist_write(vc4_state,
                                VC4_SET_FIELD(vc4_state->crtc_w,
                                              SCALER_POS1_SCL_WIDTH) |
                                VC4_SET_FIELD(vc4_state->crtc_h,
                                              SCALER_POS1_SCL_HEIGHT));
        }

        /* Position Word 2: Source Image Size, Alpha Mode */
        vc4_state->pos2_offset = vc4_state->dlist_count;
        vc4_dlist_write(vc4_state,
                        VC4_SET_FIELD(format->has_alpha ?
                                      SCALER_POS2_ALPHA_MODE_PIPELINE :
                                      SCALER_POS2_ALPHA_MODE_FIXED,
                                      SCALER_POS2_ALPHA_MODE) |
                        VC4_SET_FIELD(vc4_state->src_w[0], SCALER_POS2_WIDTH) |
                        VC4_SET_FIELD(vc4_state->src_h[0], SCALER_POS2_HEIGHT));

        /* Position Word 3: Context.  Written by the HVS. */
        vc4_dlist_write(vc4_state, 0xc0c0c0c0);


        /* Pointer Word 0/1/2: RGB / Y / Cb / Cr Pointers
         *
         * The pointers may be any byte address.
         */
        vc4_state->ptr0_offset = vc4_state->dlist_count;
        if (!format->flip_cbcr) {
                for (i = 0; i < num_planes; i++)
                        vc4_dlist_write(vc4_state, vc4_state->offsets[i]);
        } else {
                WARN_ON_ONCE(num_planes != 3);
                vc4_dlist_write(vc4_state, vc4_state->offsets[0]);
                vc4_dlist_write(vc4_state, vc4_state->offsets[2]);
                vc4_dlist_write(vc4_state, vc4_state->offsets[1]);
        }

        /* Pointer Context Word 0/1/2: Written by the HVS */
        for (i = 0; i < num_planes; i++)
                vc4_dlist_write(vc4_state, 0xc0c0c0c0);

        /* Pitch word 0/1/2 */
        for (i = 0; i < num_planes; i++) {
                vc4_dlist_write(vc4_state,
                                VC4_SET_FIELD(fb->pitches[i], SCALER_SRC_PITCH));
        }

        /* Colorspace conversion words */
        if (vc4_state->is_yuv) {
                vc4_dlist_write(vc4_state, SCALER_CSC0_ITR_R_601_5);
                vc4_dlist_write(vc4_state, SCALER_CSC1_ITR_R_601_5);
                vc4_dlist_write(vc4_state, SCALER_CSC2_ITR_R_601_5);
        }

        if (!vc4_state->is_unity) {
                /* LBM Base Address. */
                if (vc4_state->y_scaling[0] != VC4_SCALING_NONE ||
                    vc4_state->y_scaling[1] != VC4_SCALING_NONE) {
                        vc4_dlist_write(vc4_state, vc4_state->lbm.start);
                }

                if (num_planes > 1) {
                        /* Emit Cb/Cr as channel 0 and Y as channel
                         * 1. This matches how we set up scl0/scl1
                         * above.
                         */
                        vc4_write_scaling_parameters(state, 1);
                }
                vc4_write_scaling_parameters(state, 0);

                /* If any PPF setup was done, then all the kernel
                 * pointers get uploaded.
                 */
                if (vc4_state->x_scaling[0] == VC4_SCALING_PPF ||
                    vc4_state->y_scaling[0] == VC4_SCALING_PPF ||
                    vc4_state->x_scaling[1] == VC4_SCALING_PPF ||
                    vc4_state->y_scaling[1] == VC4_SCALING_PPF) {
                        u32 kernel = VC4_SET_FIELD(vc4->hvs->mitchell_netravali_filter.start,
                                                   SCALER_PPF_KERNEL_OFFSET);

                        /* HPPF plane 0 */
                        vc4_dlist_write(vc4_state, kernel);
                        /* VPPF plane 0 */
                        vc4_dlist_write(vc4_state, kernel);
                        /* HPPF plane 1 */
                        vc4_dlist_write(vc4_state, kernel);
                        /* VPPF plane 1 */
                        vc4_dlist_write(vc4_state, kernel);
                }
        }

        vc4_state->dlist[ctl0_offset] |=
                VC4_SET_FIELD(vc4_state->dlist_count, SCALER_CTL0_SIZE);

        return 0;
}

/* If a modeset involves changing the setup of a plane, the atomic
 * infrastructure will call this to validate a proposed plane setup.
 * However, if a plane isn't getting updated, this (and the
 * corresponding vc4_plane_atomic_update) won't get called.  Thus, we
 * compute the dlist here and have all active plane dlists get updated
 * in the CRTC's flush.
 */
static int vc4_plane_atomic_check(struct drm_plane *plane,
                                  struct drm_plane_state *state)
{
        struct vc4_plane_state *vc4_state = to_vc4_plane_state(state);

        vc4_state->dlist_count = 0;

        if (plane_enabled(state))
                return vc4_plane_mode_set(plane, state);
        else
                return 0;
}

static void vc4_plane_atomic_update(struct drm_plane *plane,
                                    struct drm_plane_state *old_state)
{
        /* No contents here.  Since we don't know where in the CRTC's
         * dlist we should be stored, our dlist is uploaded to the
         * hardware with vc4_plane_write_dlist() at CRTC atomic_flush
         * time.
         */
}

u32 vc4_plane_write_dlist(struct drm_plane *plane, u32 __iomem *dlist)
{
        struct vc4_plane_state *vc4_state = to_vc4_plane_state(plane->state);
        int i;

        vc4_state->hw_dlist = dlist;

        /* Can't memcpy_toio() because it needs to be 32-bit writes. */
        for (i = 0; i < vc4_state->dlist_count; i++)
                writel(vc4_state->dlist[i], &dlist[i]);

        return vc4_state->dlist_count;
}

u32 vc4_plane_dlist_size(const struct drm_plane_state *state)
{
        const struct vc4_plane_state *vc4_state =
                container_of(state, typeof(*vc4_state), base);

        return vc4_state->dlist_count;
}

/* Updates the plane to immediately (well, once the FIFO needs
 * refilling) scan out from at a new framebuffer.
 */
void vc4_plane_async_set_fb(struct drm_plane *plane, struct drm_framebuffer *fb)
{
        struct vc4_plane_state *vc4_state = to_vc4_plane_state(plane->state);
        struct drm_gem_cma_object *bo = drm_fb_cma_get_gem_obj(fb, 0);
        uint32_t addr;

        /* We're skipping the address adjustment for negative origin,
         * because this is only called on the primary plane.
         */
        WARN_ON_ONCE(plane->state->crtc_x < 0 || plane->state->crtc_y < 0);
        addr = bo->paddr + fb->offsets[0];

        /* Write the new address into the hardware immediately.  The
         * scanout will start from this address as soon as the FIFO
         * needs to refill with pixels.
         */
        writel(addr, &vc4_state->hw_dlist[vc4_state->ptr0_offset]);

        /* Also update the CPU-side dlist copy, so that any later
         * atomic updates that don't do a new modeset on our plane
         * also use our updated address.
         */
        vc4_state->dlist[vc4_state->ptr0_offset] = addr;
}

static const struct drm_plane_helper_funcs vc4_plane_helper_funcs = {
        .atomic_check = vc4_plane_atomic_check,
        .atomic_update = vc4_plane_atomic_update,
};

static void vc4_plane_destroy(struct drm_plane *plane)
{
        drm_plane_helper_disable(plane);
        drm_plane_cleanup(plane);
}

/* Implements immediate (non-vblank-synced) updates of the cursor
 * position, or falls back to the atomic helper otherwise.
 */
static int
vc4_update_plane(struct drm_plane *plane,
                 struct drm_crtc *crtc,
                 struct drm_framebuffer *fb,
                 int crtc_x, int crtc_y,
                 unsigned int crtc_w, unsigned int crtc_h,
                 uint32_t src_x, uint32_t src_y,
                 uint32_t src_w, uint32_t src_h)
{
        struct drm_plane_state *plane_state;
        struct vc4_plane_state *vc4_state;

        if (plane != crtc->cursor)
                goto out;

        plane_state = plane->state;
        vc4_state = to_vc4_plane_state(plane_state);

        if (!plane_state)
                goto out;

        /* If we're changing the cursor contents, do that in the
         * normal vblank-synced atomic path.
         */
        if (fb != plane_state->fb)
                goto out;

        /* No configuring new scaling in the fast path. */
        if (crtc_w != plane_state->crtc_w ||
            crtc_h != plane_state->crtc_h ||
            src_w != plane_state->src_w ||
            src_h != plane_state->src_h) {
                goto out;
        }

        /* Set the cursor's position on the screen.  This is the
         * expected change from the drm_mode_cursor_universal()
         * helper.
         */
        plane_state->crtc_x = crtc_x;
        plane_state->crtc_y = crtc_y;

        /* Allow changing the start position within the cursor BO, if
         * that matters.
         */
        plane_state->src_x = src_x;
        plane_state->src_y = src_y;

        /* Update the display list based on the new crtc_x/y. */
        vc4_plane_atomic_check(plane, plane_state);

        /* Note that we can't just call vc4_plane_write_dlist()
         * because that would smash the context data that the HVS is
         * currently using.
         */
        writel(vc4_state->dlist[vc4_state->pos0_offset],
               &vc4_state->hw_dlist[vc4_state->pos0_offset]);
        writel(vc4_state->dlist[vc4_state->pos2_offset],
               &vc4_state->hw_dlist[vc4_state->pos2_offset]);
        writel(vc4_state->dlist[vc4_state->ptr0_offset],
               &vc4_state->hw_dlist[vc4_state->ptr0_offset]);

        return 0;

out:
        return drm_atomic_helper_update_plane(plane, crtc, fb,
                                              crtc_x, crtc_y,
                                              crtc_w, crtc_h,
                                              src_x, src_y,
                                              src_w, src_h);
}

static const struct drm_plane_funcs vc4_plane_funcs = {
        .update_plane = vc4_update_plane,
        .disable_plane = drm_atomic_helper_disable_plane,
        .destroy = vc4_plane_destroy,
        .set_property = NULL,
        .reset = vc4_plane_reset,
        .atomic_duplicate_state = vc4_plane_duplicate_state,
        .atomic_destroy_state = vc4_plane_destroy_state,
};

struct drm_plane *vc4_plane_init(struct drm_device *dev,
                                 enum drm_plane_type type)
{
        struct drm_plane *plane = NULL;
        struct vc4_plane *vc4_plane;
        u32 formats[ARRAY_SIZE(hvs_formats)];
        u32 num_formats = 0;
        int ret = 0;
        unsigned i;

        vc4_plane = devm_kzalloc(dev->dev, sizeof(*vc4_plane),
                                 GFP_KERNEL);
        if (!vc4_plane) {
                ret = -ENOMEM;
                goto fail;
        }

        for (i = 0; i < ARRAY_SIZE(hvs_formats); i++) {
                /* Don't allow YUV in cursor planes, since that means
                 * tuning on the scaler, which we don't allow for the
                 * cursor.
                 */
                if (type != DRM_PLANE_TYPE_CURSOR ||
                    hvs_formats[i].hvs < HVS_PIXEL_FORMAT_YCBCR_YUV420_3PLANE) {
                        formats[num_formats++] = hvs_formats[i].drm;
                }
        }
        plane = &vc4_plane->base;
        ret = drm_universal_plane_init(dev, plane, 0,
                                       &vc4_plane_funcs,
                                       formats, num_formats,
                                       type, NULL);

        drm_plane_helper_add(plane, &vc4_plane_helper_funcs);

        return plane;
fail:
        if (plane)
                vc4_plane_destroy(plane);

        return ERR_PTR(ret);
}