/* Copyright 2022 The ChromiumOS Authors
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include <zephyr/logging/log.h>

#include "cros_board_info.h"
#include "cros_cbi.h"

LOG_MODULE_REGISTER(cros_cbi_fw_config, LOG_LEVEL_ERR);

/*
 * Validation macros.
 * These are moved out of header files to avoid exposing them outside
 * this file scope.
 */

/*
 * Statically count the number of bits set in a 32 bit constant expression.
 */
#define BIT_SET(v, b) ((v >> b) & 1)
#define BIT_COUNT(v)                                                         \
	(BIT_SET(v, 31) + BIT_SET(v, 30) + BIT_SET(v, 29) + BIT_SET(v, 28) + \
	 BIT_SET(v, 27) + BIT_SET(v, 26) + BIT_SET(v, 25) + BIT_SET(v, 24) + \
	 BIT_SET(v, 23) + BIT_SET(v, 22) + BIT_SET(v, 21) + BIT_SET(v, 20) + \
	 BIT_SET(v, 19) + BIT_SET(v, 18) + BIT_SET(v, 17) + BIT_SET(v, 16) + \
	 BIT_SET(v, 15) + BIT_SET(v, 14) + BIT_SET(v, 13) + BIT_SET(v, 12) + \
	 BIT_SET(v, 11) + BIT_SET(v, 10) + BIT_SET(v, 9) + BIT_SET(v, 8) +   \
	 BIT_SET(v, 7) + BIT_SET(v, 6) + BIT_SET(v, 5) + BIT_SET(v, 4) +     \
	 BIT_SET(v, 3) + BIT_SET(v, 2) + BIT_SET(v, 1) + BIT_SET(v, 0))

/*
 * Shorthand macros to access properties on the field node.
 */
#define FW_START(id) DT_PROP(id, start)
#define FW_SIZE(id) DT_PROP(id, size)

/*
 * Calculate the mask of the field from the size.
 */
#define FW_MASK(id) ((1 << FW_SIZE(id)) - 1)

/*
 * Calculate the mask and shift it to the correct start bit.
 */
#define FW_SHIFT_MASK(id) (FW_MASK(id) << FW_START(id))

/*
 * For a child "named-cbi-fw-config-value" node, retrieve the
 * size of the parent field this value is associated with.
 */
#define FW_PARENT_SIZE(id) DT_PROP(DT_PARENT(id), size)

/*
 * For a child "named-cbi-fw-config-value" node, retrieve the
 * start of the parent field this value is associated with.
 */
#define FW_PARENT_START(id) DT_PROP(DT_PARENT(id), start)

/*
 * Validation check to ensure total field sizes do not exceed 32 bits.
 * The FOREACH loop is nested, one to iterate through all the
 * fw_config nodes, and another for the child field nodes in each
 * of the fw_config nodes.
 */
#define PLUS_FIELD_SIZE(inst) +DT_PROP(inst, size)
#define FIELDS_ALL_SIZE(inst) \
	DT_FOREACH_CHILD_STATUS_OKAY(inst, PLUS_FIELD_SIZE)

/*
 * Result is the sum of all the field sizes.
 */
#define TOTAL_FW_CONFIG_NODES_SIZE \
	(0 DT_FOREACH_STATUS_OKAY(CBI_FW_CONFIG_COMPAT, FIELDS_ALL_SIZE))

BUILD_ASSERT(TOTAL_FW_CONFIG_NODES_SIZE <= 32,
	     "CBI FW Config is bigger than 32 bits");

/*
 * Validation check to ensure there are no overlapping fields.
 * OR together all the masks, count the bits, and compare against the
 * total of the sizes. They should match.
 */
#define OR_FIELD_SHIFT_MASK(id) | FW_SHIFT_MASK(id)
#define FIELDS_ALL_BITS_SET(inst) \
	DT_FOREACH_CHILD_STATUS_OKAY(inst, OR_FIELD_SHIFT_MASK)

#define TOTAL_BITS_SET \
	(0 DT_FOREACH_STATUS_OKAY(CBI_FW_CONFIG_COMPAT, FIELDS_ALL_BITS_SET))

BUILD_ASSERT(BIT_COUNT(TOTAL_BITS_SET) == TOTAL_FW_CONFIG_NODES_SIZE,
	     "CBI FW Config has overlapping fields");

/*
 * Validation for each assigned field values.
 * The value must fit within the parent's defined size.
 */
#define FW_VALUE_BUILD_ASSERT(inst)                                      \
	BUILD_ASSERT(DT_PROP(inst, value) < (1 << FW_PARENT_SIZE(inst)), \
		     "CBI FW Config value too big");

DT_FOREACH_STATUS_OKAY(CBI_FW_CONFIG_VALUE_COMPAT, FW_VALUE_BUILD_ASSERT)

/*
 * Macro to initialise the fields to default value (if specified)
 */
#define CBI_FW_CONFIG_INIT_DEFAULT(id, fw_config)            \
	do {                                                 \
		if (DT_PROP(id, default)) {                  \
			fw_config |= DT_PROP(id, value)      \
				     << FW_PARENT_START(id); \
		}                                            \
	} while (0);
/*
 * Define bit fields based on the device tree entries. Example:
 * cbi-fw-config {
 *	compatible = "named-cbi-fw-config";
 *
 *	fan {
 *		enum-name = "FW_CONFIG_FAN";
 *		start = <0>;
 *		size = <1>;
 *		fan_present {
 *			enum-name = "FW_FAN_PRESENT"
 *			compatible = "named-cbi-fw-config-value";
 *			value = <1>;
 *		};
 *	};
 * };
 *
 * Creates
 * switch (field_id) {
 * case FW_CONFIG_FAN:
 *	return (value >> 0) & 1;
 *	...
 * }
 *
 */

/*
 * The per-field case statement.
 * Extract the field value using the start and size.
 */
#define FW_FIELD_CASE(id, cached, value)                         \
	case CBI_FW_CONFIG_ENUM(id):                             \
		*value = (cached >> FW_START(id)) & FW_MASK(id); \
		break;

/*
 * Create a case for every child of this "named-cbi-fw-config" node.
 */
#define FW_FIELD_NODES(inst, cached, value) \
	DT_FOREACH_CHILD_STATUS_OKAY_VARGS(inst, FW_FIELD_CASE, cached, value)

uint32_t cached_fw_config;

void cros_cbi_fw_config_init(void)
{
	if (cbi_get_fw_config(&cached_fw_config) != EC_SUCCESS) {
		/*
		 * Missing fw config will set the default or 0 for
		 * every field.
		 */
		cached_fw_config = 0;
		DT_FOREACH_STATUS_OKAY_VARGS(CBI_FW_CONFIG_VALUE_COMPAT,
					     CBI_FW_CONFIG_INIT_DEFAULT,
					     cached_fw_config)
	}

	LOG_INF("Read CBI FW Config : 0x%08X\n", cached_fw_config);
}

static int cros_cbi_fw_config_get_field(uint32_t cached_fw_config,
					enum cbi_fw_config_field_id field_id,
					uint32_t *value)
{
	switch (field_id) {
		/*
		 * Iterate through all the the "named-cbi-fw-config" nodes,
		 * and create cases for all of their child nodes.
		 */
		DT_FOREACH_STATUS_OKAY_VARGS(CBI_FW_CONFIG_COMPAT,
					     FW_FIELD_NODES, cached_fw_config,
					     value)
	default:
		return -EINVAL;
	}
	return 0;
}

int cros_cbi_get_fw_config(enum cbi_fw_config_field_id field_id,
			   uint32_t *value)
{
	int rc;

	rc = cros_cbi_fw_config_get_field(cached_fw_config, field_id, value);
	if (rc)
		LOG_ERR("CBI FW Config field not found: %d\n", field_id);
	return rc;
}