/*
 * Copyright (C) 2017 The Linux Foundation. All rights reserved.
 *
 * 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 "mdp5_kms.h"

/*
 * As of now, there are only 2 combinations possible for source split:
 *
 * Left | Right
 * -----|------
 *  LM0 | LM1
 *  LM2 | LM5
 *
 */
static int lm_right_pair[] = { 1, -1, 5, -1, -1, -1 };

static int get_right_pair_idx(struct mdp5_kms *mdp5_kms, int lm)
{
	int i;
	int pair_lm;

	pair_lm = lm_right_pair[lm];
	if (pair_lm < 0)
		return -EINVAL;

	for (i = 0; i < mdp5_kms->num_hwmixers; i++) {
		struct mdp5_hw_mixer *mixer = mdp5_kms->hwmixers[i];

		if (mixer->lm == pair_lm)
			return mixer->idx;
	}

	return -1;
}

int mdp5_mixer_assign(struct drm_atomic_state *s, struct drm_crtc *crtc,
		      uint32_t caps, struct mdp5_hw_mixer **mixer,
		      struct mdp5_hw_mixer **r_mixer)
{
	struct msm_drm_private *priv = s->dev->dev_private;
	struct mdp5_kms *mdp5_kms = to_mdp5_kms(to_mdp_kms(priv->kms));
	struct mdp5_state *state = mdp5_get_state(s);
	struct mdp5_hw_mixer_state *new_state;
	int i;

	if (IS_ERR(state))
		return PTR_ERR(state);

	new_state = &state->hwmixer;

	for (i = 0; i < mdp5_kms->num_hwmixers; i++) {
		struct mdp5_hw_mixer *cur = mdp5_kms->hwmixers[i];

		/*
		 * skip if already in-use by a different CRTC. If there is a
		 * mixer already assigned to this CRTC, it means this call is
		 * a request to get an additional right mixer. Assume that the
		 * existing mixer is the 'left' one, and try to see if we can
		 * get its corresponding 'right' pair.
		 */
		if (new_state->hwmixer_to_crtc[cur->idx] &&
		    new_state->hwmixer_to_crtc[cur->idx] != crtc)
			continue;

		/* skip if doesn't support some required caps: */
		if (caps & ~cur->caps)
			continue;

		if (r_mixer) {
			int pair_idx;

			pair_idx = get_right_pair_idx(mdp5_kms, cur->lm);
			if (pair_idx < 0)
				return -EINVAL;

			if (new_state->hwmixer_to_crtc[pair_idx])
				continue;

			*r_mixer = mdp5_kms->hwmixers[pair_idx];
		}

		/*
		 * prefer a pair-able LM over an unpairable one. We can
		 * switch the CRTC from Normal mode to Source Split mode
		 * without requiring a full modeset if we had already
		 * assigned this CRTC a pair-able LM.
		 *
		 * TODO: There will be assignment sequences which would
		 * result in the CRTC requiring a full modeset, even
		 * if we have the LM resources to prevent it. For a platform
		 * with a few displays, we don't run out of pair-able LMs
		 * so easily. For now, ignore the possibility of requiring
		 * a full modeset.
		 */
		if (!(*mixer) || cur->caps & MDP_LM_CAP_PAIR)
			*mixer = cur;
	}

	if (!(*mixer))
		return -ENOMEM;

	if (r_mixer && !(*r_mixer))
		return -ENOMEM;

	DBG("assigning Layer Mixer %d to crtc %s", (*mixer)->lm, crtc->name);

	new_state->hwmixer_to_crtc[(*mixer)->idx] = crtc;
	if (r_mixer) {
		DBG("assigning Right Layer Mixer %d to crtc %s", (*r_mixer)->lm,
		    crtc->name);
		new_state->hwmixer_to_crtc[(*r_mixer)->idx] = crtc;
	}

	return 0;
}

void mdp5_mixer_release(struct drm_atomic_state *s, struct mdp5_hw_mixer *mixer)
{
	struct mdp5_state *state = mdp5_get_state(s);
	struct mdp5_hw_mixer_state *new_state = &state->hwmixer;

	if (!mixer)
		return;

	if (WARN_ON(!new_state->hwmixer_to_crtc[mixer->idx]))
		return;

	DBG("%s: release from crtc %s", mixer->name,
	    new_state->hwmixer_to_crtc[mixer->idx]->name);

	new_state->hwmixer_to_crtc[mixer->idx] = NULL;
}

void mdp5_mixer_destroy(struct mdp5_hw_mixer *mixer)
{
	kfree(mixer);
}

static const char * const mixer_names[] = {
	"LM0", "LM1", "LM2", "LM3", "LM4", "LM5",
};

struct mdp5_hw_mixer *mdp5_mixer_init(const struct mdp5_lm_instance *lm)
{
	struct mdp5_hw_mixer *mixer;

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

	mixer->name = mixer_names[lm->id];
	mixer->lm = lm->id;
	mixer->caps = lm->caps;
	mixer->pp = lm->pp;
	mixer->dspp = lm->dspp;
	mixer->flush_mask = mdp_ctl_flush_mask_lm(lm->id);

	return mixer;
}