// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (C) 2015 Broadcom
 */

/**
 * DOC: VC4 KMS
 *
 * This is the general code for implementing KMS mode setting that
 * doesn't clearly associate with any of the other objects (plane,
 * crtc, HDMI encoder).
 */

#include <linux/clk.h>

#include <drm/drm_atomic.h>
#include <drm/drm_atomic_helper.h>
#include <drm/drm_crtc.h>
#include <drm/drm_gem_framebuffer_helper.h>
#include <drm/drm_plane_helper.h>
#include <drm/drm_probe_helper.h>
#include <drm/drm_vblank.h>

#include "vc4_drv.h"
#include "vc4_regs.h"

#define HVS_NUM_CHANNELS 3

struct vc4_ctm_state {
        struct drm_private_state base;
        struct drm_color_ctm *ctm;
        int fifo;
};

static struct vc4_ctm_state *to_vc4_ctm_state(struct drm_private_state *priv)
{
        return container_of(priv, struct vc4_ctm_state, base);
}

struct vc4_hvs_state {
        struct drm_private_state base;

        struct {
                unsigned in_use: 1;
                struct drm_crtc_commit *pending_commit;
        } fifo_state[HVS_NUM_CHANNELS];
};

static struct vc4_hvs_state *
to_vc4_hvs_state(struct drm_private_state *priv)
{
        return container_of(priv, struct vc4_hvs_state, base);
}

struct vc4_load_tracker_state {
        struct drm_private_state base;
        u64 hvs_load;
        u64 membus_load;
};

static struct vc4_load_tracker_state *
to_vc4_load_tracker_state(struct drm_private_state *priv)
{
        return container_of(priv, struct vc4_load_tracker_state, base);
}

static struct vc4_ctm_state *vc4_get_ctm_state(struct drm_atomic_state *state,
                                               struct drm_private_obj *manager)
{
        struct drm_device *dev = state->dev;
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        struct drm_private_state *priv_state;
        int ret;

        ret = drm_modeset_lock(&vc4->ctm_state_lock, state->acquire_ctx);
        if (ret)
                return ERR_PTR(ret);

        priv_state = drm_atomic_get_private_obj_state(state, manager);
        if (IS_ERR(priv_state))
                return ERR_CAST(priv_state);

        return to_vc4_ctm_state(priv_state);
}

static struct drm_private_state *
vc4_ctm_duplicate_state(struct drm_private_obj *obj)
{
        struct vc4_ctm_state *state;

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

        __drm_atomic_helper_private_obj_duplicate_state(obj, &state->base);

        return &state->base;
}

static void vc4_ctm_destroy_state(struct drm_private_obj *obj,
                                  struct drm_private_state *state)
{
        struct vc4_ctm_state *ctm_state = to_vc4_ctm_state(state);

        kfree(ctm_state);
}

static const struct drm_private_state_funcs vc4_ctm_state_funcs = {
        .atomic_duplicate_state = vc4_ctm_duplicate_state,
        .atomic_destroy_state = vc4_ctm_destroy_state,
};

static void vc4_ctm_obj_fini(struct drm_device *dev, void *unused)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);

        drm_atomic_private_obj_fini(&vc4->ctm_manager);
}

static int vc4_ctm_obj_init(struct vc4_dev *vc4)
{
        struct vc4_ctm_state *ctm_state;

        drm_modeset_lock_init(&vc4->ctm_state_lock);

        ctm_state = kzalloc(sizeof(*ctm_state), GFP_KERNEL);
        if (!ctm_state)
                return -ENOMEM;

        drm_atomic_private_obj_init(&vc4->base, &vc4->ctm_manager, &ctm_state->base,
                                    &vc4_ctm_state_funcs);

        return drmm_add_action_or_reset(&vc4->base, vc4_ctm_obj_fini, NULL);
}

/* Converts a DRM S31.32 value to the HW S0.9 format. */
static u16 vc4_ctm_s31_32_to_s0_9(u64 in)
{
        u16 r;

        /* Sign bit. */
        r = in & BIT_ULL(63) ? BIT(9) : 0;

        if ((in & GENMASK_ULL(62, 32)) > 0) {
                /* We have zero integer bits so we can only saturate here. */
                r |= GENMASK(8, 0);
        } else {
                /* Otherwise take the 9 most important fractional bits. */
                r |= (in >> 23) & GENMASK(8, 0);
        }

        return r;
}

static void
vc4_ctm_commit(struct vc4_dev *vc4, struct drm_atomic_state *state)
{
        struct vc4_ctm_state *ctm_state = to_vc4_ctm_state(vc4->ctm_manager.state);
        struct drm_color_ctm *ctm = ctm_state->ctm;

        if (ctm_state->fifo) {
                HVS_WRITE(SCALER_OLEDCOEF2,
                          VC4_SET_FIELD(vc4_ctm_s31_32_to_s0_9(ctm->matrix[0]),
                                        SCALER_OLEDCOEF2_R_TO_R) |
                          VC4_SET_FIELD(vc4_ctm_s31_32_to_s0_9(ctm->matrix[3]),
                                        SCALER_OLEDCOEF2_R_TO_G) |
                          VC4_SET_FIELD(vc4_ctm_s31_32_to_s0_9(ctm->matrix[6]),
                                        SCALER_OLEDCOEF2_R_TO_B));
                HVS_WRITE(SCALER_OLEDCOEF1,
                          VC4_SET_FIELD(vc4_ctm_s31_32_to_s0_9(ctm->matrix[1]),
                                        SCALER_OLEDCOEF1_G_TO_R) |
                          VC4_SET_FIELD(vc4_ctm_s31_32_to_s0_9(ctm->matrix[4]),
                                        SCALER_OLEDCOEF1_G_TO_G) |
                          VC4_SET_FIELD(vc4_ctm_s31_32_to_s0_9(ctm->matrix[7]),
                                        SCALER_OLEDCOEF1_G_TO_B));
                HVS_WRITE(SCALER_OLEDCOEF0,
                          VC4_SET_FIELD(vc4_ctm_s31_32_to_s0_9(ctm->matrix[2]),
                                        SCALER_OLEDCOEF0_B_TO_R) |
                          VC4_SET_FIELD(vc4_ctm_s31_32_to_s0_9(ctm->matrix[5]),
                                        SCALER_OLEDCOEF0_B_TO_G) |
                          VC4_SET_FIELD(vc4_ctm_s31_32_to_s0_9(ctm->matrix[8]),
                                        SCALER_OLEDCOEF0_B_TO_B));
        }

        HVS_WRITE(SCALER_OLEDOFFS,
                  VC4_SET_FIELD(ctm_state->fifo, SCALER_OLEDOFFS_DISPFIFO));
}

static struct vc4_hvs_state *
vc4_hvs_get_new_global_state(struct drm_atomic_state *state)
{
        struct vc4_dev *vc4 = to_vc4_dev(state->dev);
        struct drm_private_state *priv_state;

        priv_state = drm_atomic_get_new_private_obj_state(state, &vc4->hvs_channels);
        if (IS_ERR(priv_state))
                return ERR_CAST(priv_state);

        return to_vc4_hvs_state(priv_state);
}

static struct vc4_hvs_state *
vc4_hvs_get_old_global_state(struct drm_atomic_state *state)
{
        struct vc4_dev *vc4 = to_vc4_dev(state->dev);
        struct drm_private_state *priv_state;

        priv_state = drm_atomic_get_old_private_obj_state(state, &vc4->hvs_channels);
        if (IS_ERR(priv_state))
                return ERR_CAST(priv_state);

        return to_vc4_hvs_state(priv_state);
}

static struct vc4_hvs_state *
vc4_hvs_get_global_state(struct drm_atomic_state *state)
{
        struct vc4_dev *vc4 = to_vc4_dev(state->dev);
        struct drm_private_state *priv_state;

        priv_state = drm_atomic_get_private_obj_state(state, &vc4->hvs_channels);
        if (IS_ERR(priv_state))
                return ERR_CAST(priv_state);

        return to_vc4_hvs_state(priv_state);
}

static void vc4_hvs_pv_muxing_commit(struct vc4_dev *vc4,
                                     struct drm_atomic_state *state)
{
        struct drm_crtc_state *crtc_state;
        struct drm_crtc *crtc;
        unsigned int i;

        for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
                struct vc4_crtc_state *vc4_state = to_vc4_crtc_state(crtc_state);
                u32 dispctrl;
                u32 dsp3_mux;

                if (!crtc_state->active)
                        continue;

                if (vc4_state->assigned_channel != 2)
                        continue;

                /*
                 * SCALER_DISPCTRL_DSP3 = X, where X < 2 means 'connect DSP3 to
                 * FIFO X'.
                 * SCALER_DISPCTRL_DSP3 = 3 means 'disable DSP 3'.
                 *
                 * DSP3 is connected to FIFO2 unless the transposer is
                 * enabled. In this case, FIFO 2 is directly accessed by the
                 * TXP IP, and we need to disable the FIFO2 -> pixelvalve1
                 * route.
                 */
                if (vc4_state->feed_txp)
                        dsp3_mux = VC4_SET_FIELD(3, SCALER_DISPCTRL_DSP3_MUX);
                else
                        dsp3_mux = VC4_SET_FIELD(2, SCALER_DISPCTRL_DSP3_MUX);

                dispctrl = HVS_READ(SCALER_DISPCTRL) &
                           ~SCALER_DISPCTRL_DSP3_MUX_MASK;
                HVS_WRITE(SCALER_DISPCTRL, dispctrl | dsp3_mux);
        }
}

static void vc5_hvs_pv_muxing_commit(struct vc4_dev *vc4,
                                     struct drm_atomic_state *state)
{
        struct drm_crtc_state *crtc_state;
        struct drm_crtc *crtc;
        unsigned char mux;
        unsigned int i;
        u32 reg;

        for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
                struct vc4_crtc_state *vc4_state = to_vc4_crtc_state(crtc_state);
                struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);

                if (!vc4_state->update_muxing)
                        continue;

                switch (vc4_crtc->data->hvs_output) {
                case 2:
                        mux = (vc4_state->assigned_channel == 2) ? 0 : 1;
                        reg = HVS_READ(SCALER_DISPECTRL);
                        HVS_WRITE(SCALER_DISPECTRL,
                                  (reg & ~SCALER_DISPECTRL_DSP2_MUX_MASK) |
                                  VC4_SET_FIELD(mux, SCALER_DISPECTRL_DSP2_MUX));
                        break;

                case 3:
                        if (vc4_state->assigned_channel == VC4_HVS_CHANNEL_DISABLED)
                                mux = 3;
                        else
                                mux = vc4_state->assigned_channel;

                        reg = HVS_READ(SCALER_DISPCTRL);
                        HVS_WRITE(SCALER_DISPCTRL,
                                  (reg & ~SCALER_DISPCTRL_DSP3_MUX_MASK) |
                                  VC4_SET_FIELD(mux, SCALER_DISPCTRL_DSP3_MUX));
                        break;

                case 4:
                        if (vc4_state->assigned_channel == VC4_HVS_CHANNEL_DISABLED)
                                mux = 3;
                        else
                                mux = vc4_state->assigned_channel;

                        reg = HVS_READ(SCALER_DISPEOLN);
                        HVS_WRITE(SCALER_DISPEOLN,
                                  (reg & ~SCALER_DISPEOLN_DSP4_MUX_MASK) |
                                  VC4_SET_FIELD(mux, SCALER_DISPEOLN_DSP4_MUX));

                        break;

                case 5:
                        if (vc4_state->assigned_channel == VC4_HVS_CHANNEL_DISABLED)
                                mux = 3;
                        else
                                mux = vc4_state->assigned_channel;

                        reg = HVS_READ(SCALER_DISPDITHER);
                        HVS_WRITE(SCALER_DISPDITHER,
                                  (reg & ~SCALER_DISPDITHER_DSP5_MUX_MASK) |
                                  VC4_SET_FIELD(mux, SCALER_DISPDITHER_DSP5_MUX));
                        break;

                default:
                        break;
                }
        }
}

static void vc4_atomic_commit_tail(struct drm_atomic_state *state)
{
        struct drm_device *dev = state->dev;
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        struct vc4_hvs *hvs = vc4->hvs;
        struct drm_crtc_state *new_crtc_state;
        struct drm_crtc *crtc;
        struct vc4_hvs_state *old_hvs_state;
        unsigned int channel;
        int i;

        for_each_new_crtc_in_state(state, crtc, new_crtc_state, i) {
                struct vc4_crtc_state *vc4_crtc_state;

                if (!new_crtc_state->commit)
                        continue;

                vc4_crtc_state = to_vc4_crtc_state(new_crtc_state);
                vc4_hvs_mask_underrun(dev, vc4_crtc_state->assigned_channel);
        }

        old_hvs_state = vc4_hvs_get_old_global_state(state);
        if (IS_ERR(old_hvs_state))
                return;

        for (channel = 0; channel < HVS_NUM_CHANNELS; channel++) {
                struct drm_crtc_commit *commit;
                int ret;

                if (!old_hvs_state->fifo_state[channel].in_use)
                        continue;

                commit = old_hvs_state->fifo_state[channel].pending_commit;
                if (!commit)
                        continue;

                ret = drm_crtc_commit_wait(commit);
                if (ret)
                        drm_err(dev, "Timed out waiting for commit\n");

                drm_crtc_commit_put(commit);
                old_hvs_state->fifo_state[channel].pending_commit = NULL;
        }

        if (vc4->hvs->hvs5)
                clk_set_min_rate(hvs->core_clk, 500000000);

        drm_atomic_helper_commit_modeset_disables(dev, state);

        vc4_ctm_commit(vc4, state);

        if (vc4->hvs->hvs5)
                vc5_hvs_pv_muxing_commit(vc4, state);
        else
                vc4_hvs_pv_muxing_commit(vc4, state);

        drm_atomic_helper_commit_planes(dev, state, 0);

        drm_atomic_helper_commit_modeset_enables(dev, state);

        drm_atomic_helper_fake_vblank(state);

        drm_atomic_helper_commit_hw_done(state);

        drm_atomic_helper_wait_for_flip_done(dev, state);

        drm_atomic_helper_cleanup_planes(dev, state);

        if (vc4->hvs->hvs5)
                clk_set_min_rate(hvs->core_clk, 0);
}

static int vc4_atomic_commit_setup(struct drm_atomic_state *state)
{
        struct drm_crtc_state *crtc_state;
        struct vc4_hvs_state *hvs_state;
        struct drm_crtc *crtc;
        unsigned int i;

        hvs_state = vc4_hvs_get_new_global_state(state);
        if (WARN_ON(IS_ERR(hvs_state)))
                return PTR_ERR(hvs_state);

        for_each_new_crtc_in_state(state, crtc, crtc_state, i) {
                struct vc4_crtc_state *vc4_crtc_state =
                        to_vc4_crtc_state(crtc_state);
                unsigned int channel =
                        vc4_crtc_state->assigned_channel;

                if (channel == VC4_HVS_CHANNEL_DISABLED)
                        continue;

                if (!hvs_state->fifo_state[channel].in_use)
                        continue;

                hvs_state->fifo_state[channel].pending_commit =
                        drm_crtc_commit_get(crtc_state->commit);
        }

        return 0;
}

static struct drm_framebuffer *vc4_fb_create(struct drm_device *dev,
                                             struct drm_file *file_priv,
                                             const struct drm_mode_fb_cmd2 *mode_cmd)
{
        struct drm_mode_fb_cmd2 mode_cmd_local;

        /* If the user didn't specify a modifier, use the
         * vc4_set_tiling_ioctl() state for the BO.
         */
        if (!(mode_cmd->flags & DRM_MODE_FB_MODIFIERS)) {
                struct drm_gem_object *gem_obj;
                struct vc4_bo *bo;

                gem_obj = drm_gem_object_lookup(file_priv,
                                                mode_cmd->handles[0]);
                if (!gem_obj) {
                        DRM_DEBUG("Failed to look up GEM BO %d\n",
                                  mode_cmd->handles[0]);
                        return ERR_PTR(-ENOENT);
                }
                bo = to_vc4_bo(gem_obj);

                mode_cmd_local = *mode_cmd;

                if (bo->t_format) {
                        mode_cmd_local.modifier[0] =
                                DRM_FORMAT_MOD_BROADCOM_VC4_T_TILED;
                } else {
                        mode_cmd_local.modifier[0] = DRM_FORMAT_MOD_NONE;
                }

                drm_gem_object_put(gem_obj);

                mode_cmd = &mode_cmd_local;
        }

        return drm_gem_fb_create(dev, file_priv, mode_cmd);
}

/* Our CTM has some peculiar limitations: we can only enable it for one CRTC
 * at a time and the HW only supports S0.9 scalars. To account for the latter,
 * we don't allow userland to set a CTM that we have no hope of approximating.
 */
static int
vc4_ctm_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        struct vc4_ctm_state *ctm_state = NULL;
        struct drm_crtc *crtc;
        struct drm_crtc_state *old_crtc_state, *new_crtc_state;
        struct drm_color_ctm *ctm;
        int i;

        for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
                /* CTM is being disabled. */
                if (!new_crtc_state->ctm && old_crtc_state->ctm) {
                        ctm_state = vc4_get_ctm_state(state, &vc4->ctm_manager);
                        if (IS_ERR(ctm_state))
                                return PTR_ERR(ctm_state);
                        ctm_state->fifo = 0;
                }
        }

        for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
                if (new_crtc_state->ctm == old_crtc_state->ctm)
                        continue;

                if (!ctm_state) {
                        ctm_state = vc4_get_ctm_state(state, &vc4->ctm_manager);
                        if (IS_ERR(ctm_state))
                                return PTR_ERR(ctm_state);
                }

                /* CTM is being enabled or the matrix changed. */
                if (new_crtc_state->ctm) {
                        struct vc4_crtc_state *vc4_crtc_state =
                                to_vc4_crtc_state(new_crtc_state);

                        /* fifo is 1-based since 0 disables CTM. */
                        int fifo = vc4_crtc_state->assigned_channel + 1;

                        /* Check userland isn't trying to turn on CTM for more
                         * than one CRTC at a time.
                         */
                        if (ctm_state->fifo && ctm_state->fifo != fifo) {
                                DRM_DEBUG_DRIVER("Too many CTM configured\n");
                                return -EINVAL;
                        }

                        /* Check we can approximate the specified CTM.
                         * We disallow scalars |c| > 1.0 since the HW has
                         * no integer bits.
                         */
                        ctm = new_crtc_state->ctm->data;
                        for (i = 0; i < ARRAY_SIZE(ctm->matrix); i++) {
                                u64 val = ctm->matrix[i];

                                val &= ~BIT_ULL(63);
                                if (val > BIT_ULL(32))
                                        return -EINVAL;
                        }

                        ctm_state->fifo = fifo;
                        ctm_state->ctm = ctm;
                }
        }

        return 0;
}

static int vc4_load_tracker_atomic_check(struct drm_atomic_state *state)
{
        struct drm_plane_state *old_plane_state, *new_plane_state;
        struct vc4_dev *vc4 = to_vc4_dev(state->dev);
        struct vc4_load_tracker_state *load_state;
        struct drm_private_state *priv_state;
        struct drm_plane *plane;
        int i;

        if (!vc4->load_tracker_available)
                return 0;

        priv_state = drm_atomic_get_private_obj_state(state,
                                                      &vc4->load_tracker);
        if (IS_ERR(priv_state))
                return PTR_ERR(priv_state);

        load_state = to_vc4_load_tracker_state(priv_state);
        for_each_oldnew_plane_in_state(state, plane, old_plane_state,
                                       new_plane_state, i) {
                struct vc4_plane_state *vc4_plane_state;

                if (old_plane_state->fb && old_plane_state->crtc) {
                        vc4_plane_state = to_vc4_plane_state(old_plane_state);
                        load_state->membus_load -= vc4_plane_state->membus_load;
                        load_state->hvs_load -= vc4_plane_state->hvs_load;
                }

                if (new_plane_state->fb && new_plane_state->crtc) {
                        vc4_plane_state = to_vc4_plane_state(new_plane_state);
                        load_state->membus_load += vc4_plane_state->membus_load;
                        load_state->hvs_load += vc4_plane_state->hvs_load;
                }
        }

        /* Don't check the load when the tracker is disabled. */
        if (!vc4->load_tracker_enabled)
                return 0;

        /* The absolute limit is 2Gbyte/sec, but let's take a margin to let
         * the system work when other blocks are accessing the memory.
         */
        if (load_state->membus_load > SZ_1G + SZ_512M)
                return -ENOSPC;

        /* HVS clock is supposed to run @ 250Mhz, let's take a margin and
         * consider the maximum number of cycles is 240M.
         */
        if (load_state->hvs_load > 240000000ULL)
                return -ENOSPC;

        return 0;
}

static struct drm_private_state *
vc4_load_tracker_duplicate_state(struct drm_private_obj *obj)
{
        struct vc4_load_tracker_state *state;

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

        __drm_atomic_helper_private_obj_duplicate_state(obj, &state->base);

        return &state->base;
}

static void vc4_load_tracker_destroy_state(struct drm_private_obj *obj,
                                           struct drm_private_state *state)
{
        struct vc4_load_tracker_state *load_state;

        load_state = to_vc4_load_tracker_state(state);
        kfree(load_state);
}

static const struct drm_private_state_funcs vc4_load_tracker_state_funcs = {
        .atomic_duplicate_state = vc4_load_tracker_duplicate_state,
        .atomic_destroy_state = vc4_load_tracker_destroy_state,
};

static void vc4_load_tracker_obj_fini(struct drm_device *dev, void *unused)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);

        if (!vc4->load_tracker_available)
                return;

        drm_atomic_private_obj_fini(&vc4->load_tracker);
}

static int vc4_load_tracker_obj_init(struct vc4_dev *vc4)
{
        struct vc4_load_tracker_state *load_state;

        if (!vc4->load_tracker_available)
                return 0;

        load_state = kzalloc(sizeof(*load_state), GFP_KERNEL);
        if (!load_state)
                return -ENOMEM;

        drm_atomic_private_obj_init(&vc4->base, &vc4->load_tracker,
                                    &load_state->base,
                                    &vc4_load_tracker_state_funcs);

        return drmm_add_action_or_reset(&vc4->base, vc4_load_tracker_obj_fini, NULL);
}

static struct drm_private_state *
vc4_hvs_channels_duplicate_state(struct drm_private_obj *obj)
{
        struct vc4_hvs_state *old_state = to_vc4_hvs_state(obj->state);
        struct vc4_hvs_state *state;
        unsigned int i;

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

        __drm_atomic_helper_private_obj_duplicate_state(obj, &state->base);


        for (i = 0; i < HVS_NUM_CHANNELS; i++) {
                state->fifo_state[i].in_use = old_state->fifo_state[i].in_use;
        }

        return &state->base;
}

static void vc4_hvs_channels_destroy_state(struct drm_private_obj *obj,
                                           struct drm_private_state *state)
{
        struct vc4_hvs_state *hvs_state = to_vc4_hvs_state(state);
        unsigned int i;

        for (i = 0; i < HVS_NUM_CHANNELS; i++) {
                if (!hvs_state->fifo_state[i].pending_commit)
                        continue;

                drm_crtc_commit_put(hvs_state->fifo_state[i].pending_commit);
        }

        kfree(hvs_state);
}

static const struct drm_private_state_funcs vc4_hvs_state_funcs = {
        .atomic_duplicate_state = vc4_hvs_channels_duplicate_state,
        .atomic_destroy_state = vc4_hvs_channels_destroy_state,
};

static void vc4_hvs_channels_obj_fini(struct drm_device *dev, void *unused)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);

        drm_atomic_private_obj_fini(&vc4->hvs_channels);
}

static int vc4_hvs_channels_obj_init(struct vc4_dev *vc4)
{
        struct vc4_hvs_state *state;

        state = kzalloc(sizeof(*state), GFP_KERNEL);
        if (!state)
                return -ENOMEM;

        drm_atomic_private_obj_init(&vc4->base, &vc4->hvs_channels,
                                    &state->base,
                                    &vc4_hvs_state_funcs);

        return drmm_add_action_or_reset(&vc4->base, vc4_hvs_channels_obj_fini, NULL);
}

/*
 * The BCM2711 HVS has up to 7 outputs connected to the pixelvalves and
 * the TXP (and therefore all the CRTCs found on that platform).
 *
 * The naive (and our initial) implementation would just iterate over
 * all the active CRTCs, try to find a suitable FIFO, and then remove it
 * from the pool of available FIFOs. However, there are a few corner
 * cases that need to be considered:
 *
 * - When running in a dual-display setup (so with two CRTCs involved),
 *   we can update the state of a single CRTC (for example by changing
 *   its mode using xrandr under X11) without affecting the other. In
 *   this case, the other CRTC wouldn't be in the state at all, so we
 *   need to consider all the running CRTCs in the DRM device to assign
 *   a FIFO, not just the one in the state.
 *
 * - To fix the above, we can't use drm_atomic_get_crtc_state on all
 *   enabled CRTCs to pull their CRTC state into the global state, since
 *   a page flip would start considering their vblank to complete. Since
 *   we don't have a guarantee that they are actually active, that
 *   vblank might never happen, and shouldn't even be considered if we
 *   want to do a page flip on a single CRTC. That can be tested by
 *   doing a modetest -v first on HDMI1 and then on HDMI0.
 *
 * - Since we need the pixelvalve to be disabled and enabled back when
 *   the FIFO is changed, we should keep the FIFO assigned for as long
 *   as the CRTC is enabled, only considering it free again once that
 *   CRTC has been disabled. This can be tested by booting X11 on a
 *   single display, and changing the resolution down and then back up.
 */
static int vc4_pv_muxing_atomic_check(struct drm_device *dev,
                                      struct drm_atomic_state *state)
{
        struct vc4_hvs_state *hvs_new_state;
        struct drm_crtc_state *old_crtc_state, *new_crtc_state;
        struct drm_crtc *crtc;
        unsigned int unassigned_channels = 0;
        unsigned int i;

        hvs_new_state = vc4_hvs_get_global_state(state);
        if (IS_ERR(hvs_new_state))
                return PTR_ERR(hvs_new_state);

        for (i = 0; i < ARRAY_SIZE(hvs_new_state->fifo_state); i++)
                if (!hvs_new_state->fifo_state[i].in_use)
                        unassigned_channels |= BIT(i);

        for_each_oldnew_crtc_in_state(state, crtc, old_crtc_state, new_crtc_state, i) {
                struct vc4_crtc_state *old_vc4_crtc_state =
                        to_vc4_crtc_state(old_crtc_state);
                struct vc4_crtc_state *new_vc4_crtc_state =
                        to_vc4_crtc_state(new_crtc_state);
                struct vc4_crtc *vc4_crtc = to_vc4_crtc(crtc);
                unsigned int matching_channels;
                unsigned int channel;

                /* Nothing to do here, let's skip it */
                if (old_crtc_state->enable == new_crtc_state->enable)
                        continue;

                /* Muxing will need to be modified, mark it as such */
                new_vc4_crtc_state->update_muxing = true;

                /* If we're disabling our CRTC, we put back our channel */
                if (!new_crtc_state->enable) {
                        channel = old_vc4_crtc_state->assigned_channel;
                        hvs_new_state->fifo_state[channel].in_use = false;
                        new_vc4_crtc_state->assigned_channel = VC4_HVS_CHANNEL_DISABLED;
                        continue;
                }

                /*
                 * The problem we have to solve here is that we have
                 * up to 7 encoders, connected to up to 6 CRTCs.
                 *
                 * Those CRTCs, depending on the instance, can be
                 * routed to 1, 2 or 3 HVS FIFOs, and we need to set
                 * the change the muxing between FIFOs and outputs in
                 * the HVS accordingly.
                 *
                 * It would be pretty hard to come up with an
                 * algorithm that would generically solve
                 * this. However, the current routing trees we support
                 * allow us to simplify a bit the problem.
                 *
                 * Indeed, with the current supported layouts, if we
                 * try to assign in the ascending crtc index order the
                 * FIFOs, we can't fall into the situation where an
                 * earlier CRTC that had multiple routes is assigned
                 * one that was the only option for a later CRTC.
                 *
                 * If the layout changes and doesn't give us that in
                 * the future, we will need to have something smarter,
                 * but it works so far.
                 */
                matching_channels = unassigned_channels & vc4_crtc->data->hvs_available_channels;
                if (!matching_channels)
                        return -EINVAL;

                channel = ffs(matching_channels) - 1;
                new_vc4_crtc_state->assigned_channel = channel;
                unassigned_channels &= ~BIT(channel);
                hvs_new_state->fifo_state[channel].in_use = true;
        }

        return 0;
}

static int
vc4_atomic_check(struct drm_device *dev, struct drm_atomic_state *state)
{
        int ret;

        ret = vc4_pv_muxing_atomic_check(dev, state);
        if (ret)
                return ret;

        ret = vc4_ctm_atomic_check(dev, state);
        if (ret < 0)
                return ret;

        ret = drm_atomic_helper_check(dev, state);
        if (ret)
                return ret;

        return vc4_load_tracker_atomic_check(state);
}

static struct drm_mode_config_helper_funcs vc4_mode_config_helpers = {
        .atomic_commit_setup    = vc4_atomic_commit_setup,
        .atomic_commit_tail     = vc4_atomic_commit_tail,
};

static const struct drm_mode_config_funcs vc4_mode_funcs = {
        .atomic_check = vc4_atomic_check,
        .atomic_commit = drm_atomic_helper_commit,
        .fb_create = vc4_fb_create,
};

int vc4_kms_load(struct drm_device *dev)
{
        struct vc4_dev *vc4 = to_vc4_dev(dev);
        bool is_vc5 = of_device_is_compatible(dev->dev->of_node,
                                              "brcm,bcm2711-vc5");
        int ret;

        if (!is_vc5) {
                vc4->load_tracker_available = true;

                /* Start with the load tracker enabled. Can be
                 * disabled through the debugfs load_tracker file.
                 */
                vc4->load_tracker_enabled = true;
        }

        /* Set support for vblank irq fast disable, before drm_vblank_init() */
        dev->vblank_disable_immediate = true;

        ret = drm_vblank_init(dev, dev->mode_config.num_crtc);
        if (ret < 0) {
                dev_err(dev->dev, "failed to initialize vblank\n");
                return ret;
        }

        if (is_vc5) {
                dev->mode_config.max_width = 7680;
                dev->mode_config.max_height = 7680;
        } else {
                dev->mode_config.max_width = 2048;
                dev->mode_config.max_height = 2048;
        }

        dev->mode_config.funcs = &vc4_mode_funcs;
        dev->mode_config.helper_private = &vc4_mode_config_helpers;
        dev->mode_config.preferred_depth = 24;
        dev->mode_config.async_page_flip = true;

        ret = vc4_ctm_obj_init(vc4);
        if (ret)
                return ret;

        ret = vc4_load_tracker_obj_init(vc4);
        if (ret)
                return ret;

        ret = vc4_hvs_channels_obj_init(vc4);
        if (ret)
                return ret;

        drm_mode_config_reset(dev);

        drm_kms_helper_poll_init(dev);

        return 0;
}