// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 2022-2024, Advanced Micro Devices, Inc.
 */

#include <drm/drm_device.h>
#include <drm/drm_managed.h>
#include <drm/drm_print.h>
#include <linux/bitops.h>
#include <linux/bitmap.h>
#include <linux/slab.h>

#include "aie2_solver.h"

struct partition_node {
	struct list_head	list;
	u32			nshared;	/* # shared requests */
	u32			start_col;	/* start column */
	u32			ncols;		/* # columns */
	bool			exclusive;	/* can not be shared if set */
};

struct solver_node {
	struct list_head	list;
	u64			rid;		/* Request ID from consumer */

	struct partition_node	*pt_node;
	void			*cb_arg;
	u32			dpm_level;
	u32			cols_len;
	u32			start_cols[] __counted_by(cols_len);
};

struct solver_rgroup {
	u32				rgid;
	u32				nnode;
	u32				npartition_node;

	DECLARE_BITMAP(resbit, XRS_MAX_COL);
	struct list_head		node_list;
	struct list_head		pt_node_list;
};

struct solver_state {
	struct solver_rgroup		rgp;
	struct init_config		cfg;
	struct xrs_action_ops		*actions;
};

static u32 calculate_gops(struct aie_qos *rqos)
{
	u32 service_rate = 0;

	if (rqos->latency)
		service_rate = (1000 / rqos->latency);

	if (rqos->fps > service_rate)
		return rqos->fps * rqos->gops;

	return service_rate * rqos->gops;
}

/*
 * qos_meet() - Check the QOS request can be met.
 */
static int qos_meet(struct solver_state *xrs, struct aie_qos *rqos, u32 cgops)
{
	u32 request_gops = calculate_gops(rqos) * xrs->cfg.sys_eff_factor;

	if (request_gops <= cgops)
		return 0;

	return -EINVAL;
}

/*
 * sanity_check() - Do a basic sanity check on allocation request.
 */
static int sanity_check(struct solver_state *xrs, struct alloc_requests *req)
{
	struct cdo_parts *cdop = &req->cdo;
	struct aie_qos *rqos = &req->rqos;
	u32 cu_clk_freq;

	if (cdop->ncols > xrs->cfg.total_col)
		return -EINVAL;

	/*
	 * We can find at least one CDOs groups that meet the
	 * GOPs requirement.
	 */
	cu_clk_freq = xrs->cfg.clk_list.cu_clk_list[xrs->cfg.clk_list.num_levels - 1];

	if (qos_meet(xrs, rqos, cdop->qos_cap.opc * cu_clk_freq / 1000))
		return -EINVAL;

	return 0;
}

static bool is_valid_qos_dpm_params(struct aie_qos *rqos)
{
	/*
	 * gops is retrieved from the xmodel, so it's always set
	 * fps and latency are the configurable params from the application
	 */
	if (rqos->gops > 0 && (rqos->fps > 0 ||  rqos->latency > 0))
		return true;

	return false;
}

static int set_dpm_level(struct solver_state *xrs, struct alloc_requests *req, u32 *dpm_level)
{
	struct solver_rgroup *rgp = &xrs->rgp;
	struct cdo_parts *cdop = &req->cdo;
	struct aie_qos *rqos = &req->rqos;
	u32 freq, max_dpm_level, level;
	struct solver_node *node;

	max_dpm_level = xrs->cfg.clk_list.num_levels - 1;
	/* If no QoS parameters are passed, set it to the max DPM level */
	if (!is_valid_qos_dpm_params(rqos)) {
		level = max_dpm_level;
		goto set_dpm;
	}

	/* Find one CDO group that meet the GOPs requirement. */
	for (level = 0; level < max_dpm_level; level++) {
		freq = xrs->cfg.clk_list.cu_clk_list[level];
		if (!qos_meet(xrs, rqos, cdop->qos_cap.opc * freq / 1000))
			break;
	}

	/* set the dpm level which fits all the sessions */
	list_for_each_entry(node, &rgp->node_list, list) {
		if (node->dpm_level > level)
			level = node->dpm_level;
	}

set_dpm:
	*dpm_level = level;
	return xrs->cfg.actions->set_dft_dpm_level(xrs->cfg.ddev, level);
}

static struct solver_node *rg_search_node(struct solver_rgroup *rgp, u64 rid)
{
	struct solver_node *node;

	list_for_each_entry(node, &rgp->node_list, list) {
		if (node->rid == rid)
			return node;
	}

	return NULL;
}

static void remove_partition_node(struct solver_rgroup *rgp,
				  struct partition_node *pt_node)
{
	pt_node->nshared--;
	if (pt_node->nshared > 0)
		return;

	list_del(&pt_node->list);
	rgp->npartition_node--;

	bitmap_clear(rgp->resbit, pt_node->start_col, pt_node->ncols);
	kfree(pt_node);
}

static void remove_solver_node(struct solver_rgroup *rgp,
			       struct solver_node *node)
{
	list_del(&node->list);
	rgp->nnode--;

	if (node->pt_node)
		remove_partition_node(rgp, node->pt_node);

	kfree(node);
}

static int get_free_partition(struct solver_state *xrs,
			      struct solver_node *snode,
			      struct alloc_requests *req)
{
	struct partition_node *pt_node;
	u32 ncols = req->cdo.ncols;
	u32 col, i;

	for (i = 0; i < snode->cols_len; i++) {
		col = snode->start_cols[i];
		if (find_next_bit(xrs->rgp.resbit, XRS_MAX_COL, col) >= col + ncols)
			break;
	}

	if (i == snode->cols_len)
		return -ENODEV;

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

	pt_node->nshared = 1;
	pt_node->start_col = col;
	pt_node->ncols = ncols;

	/*
	 * Always set exclusive to false for now.
	 */
	pt_node->exclusive = false;

	list_add_tail(&pt_node->list, &xrs->rgp.pt_node_list);
	xrs->rgp.npartition_node++;
	bitmap_set(xrs->rgp.resbit, pt_node->start_col, pt_node->ncols);

	snode->pt_node = pt_node;

	return 0;
}

static int allocate_partition(struct solver_state *xrs,
			      struct solver_node *snode,
			      struct alloc_requests *req)
{
	struct partition_node *pt_node, *rpt_node = NULL;
	int idx, ret;

	ret = get_free_partition(xrs, snode, req);
	if (!ret)
		return ret;

	/* try to get a share-able partition */
	list_for_each_entry(pt_node, &xrs->rgp.pt_node_list, list) {
		if (pt_node->exclusive)
			continue;

		if (rpt_node && pt_node->nshared >= rpt_node->nshared)
			continue;

		for (idx = 0; idx < snode->cols_len; idx++) {
			if (snode->start_cols[idx] != pt_node->start_col)
				continue;

			if (req->cdo.ncols != pt_node->ncols)
				continue;

			rpt_node = pt_node;
			break;
		}
	}

	if (!rpt_node)
		return -ENODEV;

	rpt_node->nshared++;
	snode->pt_node = rpt_node;

	return 0;
}

static struct solver_node *create_solver_node(struct solver_state *xrs,
					      struct alloc_requests *req)
{
	struct cdo_parts *cdop = &req->cdo;
	struct solver_node *node;
	int ret;

	node = kzalloc(struct_size(node, start_cols, cdop->cols_len), GFP_KERNEL);
	if (!node)
		return ERR_PTR(-ENOMEM);

	node->rid = req->rid;
	node->cols_len = cdop->cols_len;
	memcpy(node->start_cols, cdop->start_cols, cdop->cols_len * sizeof(u32));

	ret = allocate_partition(xrs, node, req);
	if (ret)
		goto free_node;

	list_add_tail(&node->list, &xrs->rgp.node_list);
	xrs->rgp.nnode++;
	return node;

free_node:
	kfree(node);
	return ERR_PTR(ret);
}

static void fill_load_action(struct solver_state *xrs,
			     struct solver_node *snode,
			     struct xrs_action_load *action)
{
	action->rid = snode->rid;
	action->part.start_col = snode->pt_node->start_col;
	action->part.ncols = snode->pt_node->ncols;
}

int xrs_allocate_resource(void *hdl, struct alloc_requests *req, void *cb_arg)
{
	struct xrs_action_load load_act;
	struct solver_node *snode;
	struct solver_state *xrs;
	u32 dpm_level;
	int ret;

	xrs = (struct solver_state *)hdl;

	ret = sanity_check(xrs, req);
	if (ret) {
		drm_err(xrs->cfg.ddev, "invalid request");
		return ret;
	}

	if (rg_search_node(&xrs->rgp, req->rid)) {
		drm_err(xrs->cfg.ddev, "rid %lld is in-use", req->rid);
		return -EEXIST;
	}

	snode = create_solver_node(xrs, req);
	if (IS_ERR(snode))
		return PTR_ERR(snode);

	fill_load_action(xrs, snode, &load_act);
	ret = xrs->cfg.actions->load(cb_arg, &load_act);
	if (ret)
		goto free_node;

	ret = set_dpm_level(xrs, req, &dpm_level);
	if (ret)
		goto free_node;

	snode->dpm_level = dpm_level;
	snode->cb_arg = cb_arg;

	drm_dbg(xrs->cfg.ddev, "start col %d ncols %d\n",
		snode->pt_node->start_col, snode->pt_node->ncols);

	return 0;

free_node:
	remove_solver_node(&xrs->rgp, snode);

	return ret;
}

int xrs_release_resource(void *hdl, u64 rid)
{
	struct solver_state *xrs = hdl;
	struct solver_node *node;

	node = rg_search_node(&xrs->rgp, rid);
	if (!node) {
		drm_err(xrs->cfg.ddev, "node not exist");
		return -ENODEV;
	}

	xrs->cfg.actions->unload(node->cb_arg);
	remove_solver_node(&xrs->rgp, node);

	return 0;
}

void *xrsm_init(struct init_config *cfg)
{
	struct solver_rgroup *rgp;
	struct solver_state *xrs;

	xrs = drmm_kzalloc(cfg->ddev, sizeof(*xrs), GFP_KERNEL);
	if (!xrs)
		return NULL;

	memcpy(&xrs->cfg, cfg, sizeof(*cfg));

	rgp = &xrs->rgp;
	INIT_LIST_HEAD(&rgp->node_list);
	INIT_LIST_HEAD(&rgp->pt_node_list);

	return xrs;
}