/* Reflow Oven Controller
*
* Copyright (C) 2020  Mario Hüttel <mario.huettel@gmx.net>
*
* This file is part of the Reflow Oven Controller Project.
*
* The reflow oven controller 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.
*
* The Reflow Oven Control Firmware 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 the reflow oven controller project.
* If not, see <http://www.gnu.org/licenses/>.
*/

#include <reflow-controller/safety/safety-memory.h>
#include <stm-periph/crc-unit.h>
#include <stm-periph/backup-ram.h>

#define wordsize_of(x) ((sizeof(x) / 4U) / ((sizeof(x) % 4U) ? 0U : 1U))

static enum safety_memory_state safety_memory_get_header(struct safety_memory_header *header)
{

	int res;
	enum safety_memory_state ret;

	if (!header)
		return SAFETY_MEMORY_INIT_CORRUPTED;

	res = backup_ram_get_data(0UL, (uint32_t *)header, wordsize_of(struct safety_memory_header));
	if (res)
		return SAFETY_MEMORY_INIT_CORRUPTED;

	/* Check magics */
	if (header->magic != SAFETY_MEMORY_MAGIC || header->magic_i != (uint32_t)(~SAFETY_MEMORY_MAGIC)) {
		/* Magics invalid */
		ret = SAFETY_MEMORY_INIT_FRESH;
		goto return_val;
	}

	res = 0;
	if (header->boot_status_offset < wordsize_of(struct safety_memory_header))
		res++;
	if (header->config_overrides_offset < header->boot_status_offset + wordsize_of(struct safety_memory_boot_status))
		res++;
	if (header->config_overrides_len > SAFETY_MEMORY_CONFIG_OVERRIDE_COUNT)
		res++;
	if (header->err_memory_offset < header->config_overrides_offset + header->config_overrides_len)
		res++;
	if (header->err_memory_end >= backup_ram_get_size_in_words() || header->err_memory_end < header->err_memory_offset)
		res++;

	if (res) {
		/* Error detected: Write new header */
		ret = SAFETY_MEMORY_INIT_CORRUPTED;
	} else {
		ret = SAFETY_MEMORY_INIT_VALID_MEMORY;
	}

return_val:
	return ret;
}

static void safety_memory_write_new_header(void)
{
	struct safety_memory_header header;

	header.boot_status_offset = sizeof(struct safety_memory_header);
	header.config_overrides_offset = header.boot_status_offset + sizeof(struct safety_memory_boot_status)/4;
	header.err_memory_offset = header.config_overrides_offset + SAFETY_MEMORY_CONFIG_OVERRIDE_COUNT;
	header.err_memory_end = header.err_memory_offset;

	backup_ram_wipe();
	backup_ram_write_data(0UL, (uint32_t *)&header, wordsize_of(header));
}

static int safety_memory_check_crc()
{
	struct safety_memory_header header;
	enum safety_memory_state state = safety_memory_get_header(&header);
	uint32_t crc_offset;
	uint32_t data;
	uint32_t addr;
	int res;

	if (state != SAFETY_MEMORY_INIT_VALID_MEMORY)
		return -1;

	crc_offset = header.err_memory_end;

	crc_unit_reset();

	for (addr = 0; addr < crc_offset; addr++) {
		res = backup_ram_get_data(addr, &data, 1UL);
		if (res)
			return -2000;
		crc_unit_input(data);
	}

	res = backup_ram_get_data(crc_offset, &data, 1UL);
	if (res)
		return -2001;

	if (crc_unit_get_crc() != data)
		return -3000;
	else
		return 0;
}

static int safety_memory_gen_crc()
{
	struct safety_memory_header header;
	uint32_t word_addr;
	uint32_t data;
	int res;

	if (safety_memory_get_header(&header) != SAFETY_MEMORY_INIT_VALID_MEMORY)
		return -1;

	crc_unit_reset();
	for (word_addr = 0; word_addr < header.err_memory_end; word_addr++) {
		res = backup_ram_get_data(word_addr, &data, 1);
		if (res)
			return -2;
		crc_unit_input(data);
	}

	/* Write CRC */
	data = crc_unit_get_crc();
	res = backup_ram_write_data(header.err_memory_end, &data, 1UL);
	if (res)
		return -3;

	return 0;
}

int safety_memory_init(enum safety_memory_state *found_state)
{
	struct safety_memory_header header;
	int res;
	int ret = -1;

	if (!found_state)
		return -1001;

	crc_unit_init();
	backup_ram_init(true);

	*found_state = safety_memory_get_header(&header);

	switch (*found_state) {
	case SAFETY_MEMORY_INIT_VALID_MEMORY:
		/* Valid memory detected. Check CRC */
		res = safety_memory_check_crc();
		if (res)
			*found_state = SAFETY_MEMORY_INIT_CORRUPTED;
		break;
	case SAFETY_MEMORY_INIT_FRESH:
		safety_memory_write_new_header();
		break;
	case SAFETY_MEMORY_INIT_CORRUPTED:
	default:
		*found_state = SAFETY_MEMORY_INIT_CORRUPTED;
		safety_memory_write_new_header();
		break;
	}

	/* Check if memory header was written newly */
	if (*found_state != SAFETY_MEMORY_INIT_VALID_MEMORY) {
		/* If yes, generate new CRC checksum */
		res = safety_memory_gen_crc();
		if (res)
			ret = -100;
		else
			ret = 0;
	}

	return ret;
}

int safety_memory_get_boot_status(struct safety_memory_boot_status *status);

int safety_memory_get_error_entry_count(uint32_t *count);

int safety_memory_check(void)
{
	int res;

	res = safety_memory_check_crc();
	return -!!res;
}

int safety_memory_get_error_entry(uint32_t idx, struct error_memory_entry *entry);

int safety_memory_insert_error_entry(struct error_memory_entry *entry);

int safety_memory_insert_config_override(struct config_override *config_override);

int safety_memory_get_config_override_count(uint32_t *count);

int safety_memory_get_config_override(uint32_t idx, struct config_override *config_override);