// SPDX-License-Identifier: BSD-2-Clause
/*
 * Copyright (c) 2021, Bootlin
 */

#include <assert.h>
#include <drivers/clk.h>
#include <drivers/clk_dt.h>
#include <initcall.h>
#include <kernel/boot.h>
#include <kernel/panic.h>
#include <libfdt.h>
#include <stddef.h>

struct clk_dt_provider {
	int nodeoffset;
	unsigned int clock_cells;
	uint32_t phandle;
	clk_dt_get_func get_dt_clk;
	void *data;
	SLIST_ENTRY(clk_dt_provider) link;
};

static SLIST_HEAD(, clk_dt_provider) clk_dt_provider_list =
				SLIST_HEAD_INITIALIZER(clk_dt_provider_list);

static int fdt_clock_cells(const void *fdt, int nodeoffset)
{
	const fdt32_t *c = NULL;
	int len = 0;

	c = fdt_getprop(fdt, nodeoffset, "#clock-cells", &len);
	if (!c)
		return len;

	if (len != sizeof(*c))
		return -FDT_ERR_BADNCELLS;

	return (int)fdt32_to_cpu(*c);
}

TEE_Result clk_dt_register_clk_provider(const void *fdt, int nodeoffset,
					clk_dt_get_func get_dt_clk, void *data)
{
	struct clk_dt_provider *prv = NULL;
	int clock_cells = 0;

	prv = calloc(1, sizeof(*prv));
	if (!prv)
		return TEE_ERROR_OUT_OF_MEMORY;

	prv->get_dt_clk = get_dt_clk;
	prv->data = data;
	prv->nodeoffset = nodeoffset;
	clock_cells = fdt_clock_cells(fdt, nodeoffset);
	if (clock_cells < 0) {
		free(prv);
		return TEE_ERROR_GENERIC;
	}
	prv->clock_cells = clock_cells;
	prv->phandle = fdt_get_phandle(fdt, nodeoffset);

	SLIST_INSERT_HEAD(&clk_dt_provider_list, prv, link);

	return TEE_SUCCESS;
}

static TEE_Result clk_dt_release_provider(void)
{
	struct clk_dt_provider *prv = NULL;

	while (!SLIST_EMPTY(&clk_dt_provider_list)) {
		prv = SLIST_FIRST(&clk_dt_provider_list);
		SLIST_REMOVE_HEAD(&clk_dt_provider_list, link);
		free(prv);
	}

	return TEE_SUCCESS;
}

driver_init_late(clk_dt_release_provider);

static struct clk_dt_provider *clk_get_provider_by_node(int nodeoffset)
{
	struct clk_dt_provider *prv = NULL;

	SLIST_FOREACH(prv, &clk_dt_provider_list, link)
		if (prv->nodeoffset == nodeoffset)
			return prv;

	return NULL;
}

static struct clk_dt_provider *clk_get_provider_by_phandle(uint32_t phandle)
{
	struct clk_dt_provider *prv = NULL;

	SLIST_FOREACH(prv, &clk_dt_provider_list, link)
		if (prv->phandle == phandle)
			return prv;

	return NULL;
}

static struct clk *clk_dt_get_from_provider(struct clk_dt_provider *prv,
					    unsigned int clock_cells,
					    const uint32_t *prop)
{
	unsigned int arg = 0;
	struct clk *clk = NULL;
	struct clk_dt_phandle_args pargs = { };

	pargs.args_count = clock_cells;
	pargs.args = calloc(pargs.args_count, sizeof(uint32_t));
	if (!pargs.args)
		return NULL;

	for (arg = 0; arg < clock_cells; arg++)
		pargs.args[arg] = fdt32_to_cpu(prop[arg + 1]);

	clk = prv->get_dt_clk(&pargs, prv->data);
	free(pargs.args);

	return clk;
}

struct clk *clk_dt_get_by_name(const void *fdt, int nodeoffset,
			       const char *name)
{
	int clk_id = 0;

	clk_id = fdt_stringlist_search(fdt, nodeoffset, "clock-names", name);
	if (clk_id < 0)
		return NULL;

	return clk_dt_get_by_idx(fdt, nodeoffset, clk_id);
}

static struct clk *clk_dt_get_by_idx_prop(const char *prop_name,
					  const void *fdt, int nodeoffset,
					  unsigned int clk_idx)
{
	int len = 0;
	int idx = 0;
	int idx32 = 0;
	int clock_cells = 0;
	uint32_t phandle = 0;
	const uint32_t *prop = NULL;
	struct clk_dt_provider *prv = NULL;

	prop = fdt_getprop(fdt, nodeoffset, prop_name, &len);
	if (!prop)
		return NULL;

	while (idx < len) {
		idx32 = idx / sizeof(uint32_t);
		phandle = fdt32_to_cpu(prop[idx32]);

		prv = clk_get_provider_by_phandle(phandle);
		if (!prv)
			return NULL;

		clock_cells = prv->clock_cells;
		if (clk_idx) {
			clk_idx--;
			idx += sizeof(phandle) + clock_cells * sizeof(uint32_t);
			continue;
		}

		return clk_dt_get_from_provider(prv, clock_cells, &prop[idx32]);
	}

	return NULL;
}

struct clk *clk_dt_get_by_idx(const void *fdt, int nodeoffset,
			      unsigned int clk_idx)
{
	return clk_dt_get_by_idx_prop("clocks", fdt, nodeoffset, clk_idx);
}

static const struct clk_driver *
clk_get_compatible_driver(const char *compat,
			  const struct dt_device_match **out_dm)
{
	const struct dt_driver *drv = NULL;
	const struct dt_device_match *dm = NULL;
	const struct clk_driver *clk_drv = NULL;

	for_each_dt_driver(drv) {
		if (drv->type != DT_DRIVER_CLK)
			continue;

		clk_drv = (const struct clk_driver *)drv->driver;
		for (dm = drv->match_table; dm && dm->compatible; dm++) {
			if (strcmp(dm->compatible, compat) == 0) {
				if (out_dm)
					*out_dm = dm;

				return clk_drv;
			}
		}
	}

	return NULL;
}

/* Recursively called from parse_clock_property() */
static TEE_Result clk_probe_clock_provider_node(const void *fdt, int node);

static TEE_Result parse_clock_property(const void *fdt, int node)
{
	int len = 0;
	int idx = 0;
	int parent_node = 0;
	int clock_cells = 0;
	uint32_t phandle = 0;
	const uint32_t *prop = NULL;
	TEE_Result res = TEE_ERROR_GENERIC;

	prop = fdt_getprop(fdt, node, "clocks", &len);
	if (!prop)
		return TEE_SUCCESS;

	len /= sizeof(uint32_t);
	while (idx < len) {
		phandle = fdt32_to_cpu(prop[idx]);

		parent_node = fdt_node_offset_by_phandle(fdt, phandle);
		if (parent_node < 0)
			return TEE_ERROR_GENERIC;

		/* Parent probe should not fail or clock won't be available */
		res = clk_probe_clock_provider_node(fdt, parent_node);
		if (res)
			panic("Failed to probe parent clock");

		clock_cells = fdt_clock_cells(fdt, parent_node);
		if (clock_cells < 0)
			return TEE_ERROR_GENERIC;

		idx += 1 + clock_cells;
	}

	return TEE_SUCCESS;
}

static TEE_Result clk_dt_node_clock_probe_driver(const void *fdt, int node)
{
	int idx = 0;
	int len = 0;
	int count = 0;
	const char *compat = NULL;
	TEE_Result res = TEE_ERROR_GENERIC;
	const struct clk_driver *clk_drv = NULL;
	const struct dt_device_match *dm = NULL;

	count = fdt_stringlist_count(fdt, node, "compatible");
	if (count < 0)
		return TEE_ERROR_GENERIC;

	for (idx = 0; idx < count; idx++) {
		compat = fdt_stringlist_get(fdt, node, "compatible", idx, &len);
		if (!compat)
			return TEE_ERROR_GENERIC;

		clk_drv = clk_get_compatible_driver(compat, &dm);
		if (!clk_drv)
			continue;

		res = clk_drv->probe(fdt, node, dm->compat_data);
		if (res != TEE_SUCCESS) {
			EMSG("Failed to probe clock driver for compatible %s",
			     compat);
			panic();
		} else {
			return TEE_SUCCESS;
		}
	}

	return TEE_ERROR_GENERIC;
}

static TEE_Result clk_probe_clock_provider_node(const void *fdt, int node)
{
	int len = 0;
	int status = 0;
	TEE_Result res = TEE_ERROR_GENERIC;

	status = _fdt_get_status(fdt, node);
	if (!(status & DT_STATUS_OK_SEC))
		return TEE_ERROR_ITEM_NOT_FOUND;

	/* Check if the node is a clock provider */
	if (!fdt_getprop(fdt, node, "#clock-cells", &len))
		return TEE_ERROR_ITEM_NOT_FOUND;

	/* Check if node has already been probed */
	if (clk_get_provider_by_node(node))
		return TEE_SUCCESS;

	/* Check if the node has a clock property first to probe parent */
	res = parse_clock_property(fdt, node);
	if (res)
		return res;

	return clk_dt_node_clock_probe_driver(fdt, node);
}

static void clk_probe_node(const void *fdt, int parent_node)
{
	int child = 0;
	int status = 0;
	__maybe_unused TEE_Result res = TEE_ERROR_GENERIC;

	fdt_for_each_subnode(child, fdt, parent_node) {
		status = _fdt_get_status(fdt, child);
		if (status == DT_STATUS_DISABLED)
			continue;

		res = clk_probe_clock_provider_node(fdt, child);
		assert(res == TEE_SUCCESS || res == TEE_ERROR_ITEM_NOT_FOUND);

		clk_probe_node(fdt, child);
	}
}

static void parse_assigned_clock(const void *fdt, int nodeoffset)
{
	int rate_len = 0;
	int clock_idx = 0;
	struct clk *clk = NULL;
	unsigned long rate = 0;
	struct clk *parent = NULL;
	const uint32_t *rate_prop = NULL;

	rate_prop = fdt_getprop(fdt, nodeoffset, "assigned-clock-rates",
				&rate_len);
	rate_len /= sizeof(uint32_t);

	while (1) {
		clk = clk_dt_get_by_idx_prop("assigned-clocks", fdt, nodeoffset,
					     clock_idx);
		if (!clk)
			return;

		parent = clk_dt_get_by_idx_prop("assigned-clock-parents", fdt,
						nodeoffset, clock_idx);
		if (parent) {
			if (clk_set_parent(clk, parent)) {
				EMSG("Could not set clk %s parent to clock %s",
				     clk->name, parent->name);
				panic();
			}
		}

		if (rate_prop && clock_idx <= rate_len) {
			rate = fdt32_to_cpu(rate_prop[clock_idx]);
			if (rate && clk_set_rate(clk, rate) != TEE_SUCCESS)
				panic();
		}

		clock_idx++;
	}
}

static void clk_probe_assigned(const void *fdt, int parent_node)
{
	int len = 0;
	int child = 0;
	int status = 0;

	fdt_for_each_subnode(child, fdt, parent_node) {
		clk_probe_assigned(fdt, child);

		status = _fdt_get_status(fdt, child);
		if (status == DT_STATUS_DISABLED)
			continue;

		if (fdt_getprop(fdt, child, "assigned-clocks", &len))
			parse_assigned_clock(fdt, child);
	}
}

static TEE_Result clk_dt_probe(void)
{
	const void *fdt = get_embedded_dt();

	DMSG("Probing clocks from devicetree");
	if (!fdt)
		panic();

	clk_probe_node(fdt, -1);

	clk_probe_assigned(fdt, -1);

	return TEE_SUCCESS;
}
early_init(clk_dt_probe);