/* Copyright 2016 The Chromium OS Authors. All rights reserved.
 * Use of this source code is governed by a BSD-style license that can be
 * found in the LICENSE file.
 */

#include "common.h"
#include "console.h"
#include "flash.h"
#include "nvmem.h"
#include "shared_mem.h"
#include "task.h"
#include "timer.h"
#include "util.h"

#define CPRINTF(format, args...) cprintf(CC_COMMAND, format, ## args)
#define CPRINTS(format, args...) cprints(CC_COMMAND, format, ## args)

#define NVMEM_ACQUIRE_CACHE_SLEEP_MS 25
#define NVMEM_ACQUIRE_CACHE_MAX_ATTEMPTS (250 / NVMEM_ACQUIRE_CACHE_SLEEP_MS)
#define NVMEM_NOT_INITIALIZED (-1)

/* Table of start addresses for each partition */
static const uintptr_t nvmem_base_addr[NVMEM_NUM_PARTITIONS] = {
		CONFIG_FLASH_NVMEM_BASE_A,
		CONFIG_FLASH_NVMEM_BASE_B
	};
/* Table of offset within flash space to start of each partition */
static const uint32_t nvmem_flash_offset[NVMEM_NUM_PARTITIONS] = {
		CONFIG_FLASH_NVMEM_OFFSET_A,
		CONFIG_FLASH_NVMEM_OFFSET_B
	};

/* NvMem user buffer start offset table */
static uint32_t nvmem_user_start_offset[NVMEM_NUM_USERS];

/* A/B partion that is most up to date */
static int nvmem_act_partition;

/* NvMem cache memory structure */
struct nvmem_cache {
	uint8_t *base_ptr;
	task_id_t task;
	struct mutex mtx;
};

struct nvmem_cache cache;

/* NvMem error state */
static int nvmem_error_state;
/* Flag to track if an Nv write/move is not completed */
static int nvmem_write_error;

static int nvmem_verify_partition_sha(int index)
{
	uint8_t sha_comp[NVMEM_SHA_SIZE];
	struct nvmem_partition *p_part;
	uint8_t *p_data;

	p_part = (struct nvmem_partition *)nvmem_base_addr[index];
	p_data = (uint8_t *)p_part;
	p_data += sizeof(sha_comp);

	/* Number of bytes to compute sha over */
	nvmem_compute_sha(p_data,
			  (NVMEM_PARTITION_SIZE - NVMEM_SHA_SIZE),
			  sha_comp,
			  NVMEM_SHA_SIZE);
	/* Check if computed value matches stored value. */
	return memcmp(p_part->tag.sha, sha_comp, NVMEM_SHA_SIZE);
}

static int nvmem_acquire_cache(void)
{
	int attempts = 0;
	uint8_t *shared_mem_ptr;
	uint8_t *p_src;
	int ret;

	if (shared_mem_size() < NVMEM_PARTITION_SIZE) {
		CPRINTF("Not enough shared mem! avail = 0x%x < reqd = 0x%x\n",
			shared_mem_size(), NVMEM_PARTITION_SIZE);
		return EC_ERROR_OVERFLOW;
	}

	while (attempts < NVMEM_ACQUIRE_CACHE_MAX_ATTEMPTS) {
		ret = shared_mem_acquire(NVMEM_PARTITION_SIZE,
					 (char **)&shared_mem_ptr);
		if (ret == EC_SUCCESS) {
			/* Copy partiion contents from flash into cache */
			p_src = (uint8_t *)nvmem_base_addr[nvmem_act_partition];
			memcpy(shared_mem_ptr, p_src, NVMEM_PARTITION_SIZE);
			/* Now that cache is up to date, assign pointer */
			cache.base_ptr = shared_mem_ptr;
			return EC_SUCCESS;
		} else if (ret == EC_ERROR_BUSY) {
			CPRINTF("Shared Mem not avail! Attempt %d\n", attempts);
			/* wait NVMEM_ACQUIRE_CACHE_SLEEP_MS  msec */
			/* TODO: what time really makes sense? */
			msleep(NVMEM_ACQUIRE_CACHE_SLEEP_MS);
		}
		attempts++;
	}
	/* Timeout Error condition */
	CPRINTF("%s:%d\n", __func__, __LINE__);
	return EC_ERROR_TIMEOUT;
}

static int nvmem_lock_cache(void)
{
	/*
	 * Need to protect the cache contents and pointer value from other tasks
	 * attempting to do nvmem write operations. However, since this function
	 * may be called mutliple times prior to the mutex lock being released,
	 * there is a check first to see if the current task holds the lock. If
	 * it does then the task number will equal the value in cache.task. If
	 * the lock is held by a different task then mutex_lock function will
	 * operate as normal.
	 */
	if (cache.task != task_get_current()) {
		mutex_lock(&cache.mtx);
		cache.task = task_get_current();
	} else
		/* Lock is held by current task, nothing else to do. */
		return EC_SUCCESS;

	/*
	 * Acquire the shared memory buffer and copy the full
	 * partition size from flash into the cache buffer.
	 */
	if (nvmem_acquire_cache() != EC_SUCCESS) {
		/* Shared memory not available, need to release lock */
		/* Set task number to value that can't match a valid task */
		cache.task = TASK_ID_COUNT;
		/* Release lock */
		mutex_unlock(&cache.mtx);
		return EC_ERROR_TIMEOUT;
	}

	return EC_SUCCESS;
}

static void nvmem_release_cache(void)
{
	/* Done with shared memory buffer, release it. */
	shared_mem_release(cache.base_ptr);
	/* Inidicate cache is not available */
	cache.base_ptr = NULL;
	/* Reset task number to max value */
	cache.task = TASK_ID_COUNT;
	/* Release mutex lock here */
	mutex_unlock(&cache.mtx);
}

static int nvmem_is_unitialized(void)
{
	int p;
	int n;
	int ret;
	uint32_t *p_nvmem;
	struct nvmem_partition *p_part;

	for (p = 0; p < NVMEM_NUM_PARTITIONS; p++) {
		/* Point to start of Nv Memory */
		p_nvmem = (uint32_t *)nvmem_base_addr[p];
		/* Verify that each byte is 0xff (4 bytes at a time) */
		for (n = 0; n < (NVMEM_PARTITION_SIZE >> 2); n++)
			if (p_nvmem[n] != 0xffffffff)
				return EC_ERROR_CRC;
	}

	/*
	 * NvMem is fully unitialized. Need to initialize tag and write tag to
	 * flash so at least 1 partition is ready to be used.
	 */
	nvmem_act_partition = 0;
	/* Need to acquire the shared memory buffer */
	ret = nvmem_lock_cache();
	if (ret != EC_SUCCESS)
		return ret;
	p_part = (struct nvmem_partition *)cache.base_ptr;
	/* Start with version 0 */
	p_part->tag.version = 0;
	/* Compute sha with updated tag */
	nvmem_compute_sha(&cache.base_ptr[NVMEM_SHA_SIZE],
			  NVMEM_PARTITION_SIZE - NVMEM_SHA_SIZE,
			  p_part->tag.sha,
			  NVMEM_SHA_SIZE);
	/*
	 * Partition 0 is initialized, write tag only to flash. Since the
	 * partition was just verified to be fully erased, can just do write
	 * operation.
	 */
	ret = flash_physical_write(nvmem_flash_offset[0],
				   sizeof(struct nvmem_tag),
				   cache.base_ptr);
	nvmem_release_cache();
	if (ret) {
		CPRINTF("%s:%d\n", __func__, __LINE__);
		return ret;
	}
	return EC_SUCCESS;
}

static int nvmem_compare_version(void)
{
	struct nvmem_partition *p_part;
	uint16_t ver0, ver1;
	uint32_t delta;

	p_part = (struct nvmem_partition *)nvmem_base_addr[0];
	ver0 = p_part->tag.version;
	p_part = (struct nvmem_partition *)nvmem_base_addr[1];
	ver1 = p_part->tag.version;

	/* Compute version difference accounting for wrap condition */
	delta = (ver0 - ver1 + (1<<NVMEM_VERSION_BITS)) & NVMEM_VERSION_MASK;
	/*
	 * If version number delta is positive in a circular sense then
	 * partition 0 has the newest version number. Otherwise, it's
	 * partition 1.
	 */
	return delta < (1<<(NVMEM_VERSION_BITS-1)) ? 0 : 1;
}

static int nvmem_find_partition(void)
{
	int n;

	/* Don't know which partition to use yet */
	nvmem_act_partition = NVMEM_NOT_INITIALIZED;
	/*
	 * Check each partition to determine if the sha is good. If both
	 * partitions have valid sha(s), then compare version numbers to select
	 * the most recent one.
	 */
	for (n = 0; n < NVMEM_NUM_PARTITIONS; n++)
		if (nvmem_verify_partition_sha(n) == EC_SUCCESS) {
			if (nvmem_act_partition == NVMEM_NOT_INITIALIZED)
				nvmem_act_partition = n;
			else
				nvmem_act_partition = nvmem_compare_version();
		}
	/*
	 * If active_partition is still not selected, then neither partition is
	 * valid. In this case need to determine if they are simply erased or
	 * both are corrupt. If erased, then can initialze the tag for the first
	 * one. If not fully erased, then this is an error condition.
	 */
	if (nvmem_act_partition != NVMEM_NOT_INITIALIZED)
		return EC_SUCCESS;

	if (nvmem_is_unitialized()) {
		CPRINTS("NvMem: No Valid Paritions!");
		return EC_ERROR_UNKNOWN;
	}

	return EC_SUCCESS;
}

static int nvmem_generate_offset_table(void)
{
	int n;
	uint32_t start_offset;

	/*
	 * Create table of starting offsets within partition for each user
	 * buffer that's been defined.
	 */
	start_offset = sizeof(struct nvmem_tag);
	for (n = 0; n < NVMEM_NUM_USERS; n++) {
		nvmem_user_start_offset[n] = start_offset;
		start_offset += nvmem_user_sizes[n];
	}
	/* Verify that all defined user buffers fit within the partition */
	if (start_offset > NVMEM_PARTITION_SIZE)
		return EC_ERROR_OVERFLOW;

	return EC_SUCCESS;
}
static int nvmem_get_partition_off(int user, uint32_t offset,
				   uint32_t len, uint32_t *p_buf_offset)
{
	uint32_t start_offset;

	/* Sanity check for user */
	if (user >= NVMEM_NUM_USERS)
		return EC_ERROR_OVERFLOW;

	/* Get offset within the partition for the start of user buffer */
	start_offset = nvmem_user_start_offset[user];
	/*
	 * Ensure that read/write operation that is calling this function
	 * doesn't exceed the end of its buffer.
	 */
	if (offset + len > nvmem_user_sizes[user])
		return EC_ERROR_OVERFLOW;
	/* Compute offset within the partition for the rd/wr operation */
	*p_buf_offset = start_offset + offset;

	return EC_SUCCESS;
}

int nvmem_setup(uint8_t starting_version)
{
	struct nvmem_partition *p_part;
	int part;
	int ret;

	CPRINTS("Configuring NVMEM FLash Partition");
	/*
	 * Initialize NVmem partition. This function will only be called
	 * if during nvmem_init() fails which implies that NvMem is not fully
	 * erased and neither partion tag contains a valid sha meaning they are
	 * both corrupted
	 */
	for (part = 0; part < NVMEM_NUM_PARTITIONS; part++) {
		/* Set active partition variable */
		nvmem_act_partition = part;

		/* Get the cache buffer */
		if (nvmem_lock_cache() != EC_SUCCESS) {
			CPRINTF("NvMem: Cache ram not available!\n");
			return EC_ERROR_TIMEOUT;
		}
		/* Fill entire partition to 0xFFs */
		memset(cache.base_ptr, 0xff, NVMEM_PARTITION_SIZE);
		/* Get pointer to start of partition */
		p_part = (struct nvmem_partition *)cache.base_ptr;
		/* Commit function will increment version number */
		p_part->tag.version = starting_version + part - 1;
		/* Compute sha for the partition */
		nvmem_compute_sha(&cache.base_ptr[NVMEM_SHA_SIZE],
				  NVMEM_PARTITION_SIZE -
				  NVMEM_SHA_SIZE,
				  p_part->tag.sha,
				  NVMEM_SHA_SIZE);
		/* Partition is now ready, write it to flash. */
		ret = nvmem_commit();
		if (ret != EC_SUCCESS)
			return ret;
	}

	return EC_SUCCESS;
}

int nvmem_init(void)
{
	int ret;

	/* Generate start offsets within partiion for user buffers */
	ret = nvmem_generate_offset_table();
	if (ret) {
		CPRINTF("%s:%d\n", __func__, __LINE__);
		return ret;
	}
	/* Initialize error state, assume everything is good */
	nvmem_error_state = EC_SUCCESS;
	nvmem_write_error = 0;
	/* Default state for cache base_ptr and task number */
	cache.base_ptr = NULL;
	cache.task = TASK_ID_COUNT;

	ret = nvmem_find_partition();
	if (ret != EC_SUCCESS) {
		/* Write NvMem partitions to 0xff and setup new tags */
		nvmem_setup(0);
		/* Should find valid partiion now */
		ret = nvmem_find_partition();
		if (ret) {
			/* Change error state to non-zero */
			nvmem_error_state = EC_ERROR_UNKNOWN;
			CPRINTF("%s:%d\n", __func__, __LINE__);
			return ret;
		}
	}

	CPRINTS("Active NVram partition set to %d", nvmem_act_partition);
	return EC_SUCCESS;
}

int nvmem_get_error_state(void)
{
	return nvmem_error_state;
}

int nvmem_is_different(uint32_t offset, uint32_t size, void *data,
		       enum nvmem_users user)
{
	int ret;
	uint8_t *p_src;
	uintptr_t src_addr;
	uint32_t src_offset;

	/* Point to either NvMem flash or ram if that's active */
	if (cache.base_ptr == NULL)
		src_addr = nvmem_base_addr[nvmem_act_partition];

	else
		src_addr = (uintptr_t)cache.base_ptr;

	/* Get partition offset for this read operation */
	ret = nvmem_get_partition_off(user, offset, size, &src_offset);
	if (ret != EC_SUCCESS)
		return ret;

	/* Advance to the correct byte within the data buffer */
	src_addr += src_offset;
	p_src = (uint8_t *)src_addr;
	/* Compare NvMem with data */
	return memcmp(p_src, data, size);
}

int nvmem_read(uint32_t offset, uint32_t size,
		    void *data, enum nvmem_users user)
{
	int ret;
	uint8_t *p_src;
	uintptr_t src_addr;
	uint32_t src_offset;

	/* Point to either NvMem flash or ram if that's active */
	if (cache.base_ptr == NULL)
		src_addr = nvmem_base_addr[nvmem_act_partition];

	else
		src_addr = (uintptr_t)cache.base_ptr;
	/* Get partition offset for this read operation */
	ret = nvmem_get_partition_off(user, offset, size, &src_offset);
	if (ret != EC_SUCCESS)
		return ret;
	/* Advance to the correct byte within the data buffer */
	src_addr += src_offset;
	p_src = (uint8_t *)src_addr;

	/* Copy from src into the caller's destination buffer */
	memcpy(data, p_src, size);

	return EC_SUCCESS;
}

int nvmem_write(uint32_t offset, uint32_t size,
		 void *data, enum nvmem_users user)
{
	int ret;
	uint8_t *p_dest;
	uintptr_t dest_addr;
	uint32_t dest_offset;

	/* Make sure that the cache buffer is active */
	ret = nvmem_lock_cache();
	if (ret) {
		nvmem_write_error = 1;
		return ret;
	}

	/* Compute partition offset for this write operation */
	ret = nvmem_get_partition_off(user, offset, size, &dest_offset);
	if (ret != EC_SUCCESS) {
		nvmem_write_error = 1;
		return ret;
	}

	/* Advance to correct offset within data buffer */
	dest_addr = (uintptr_t)cache.base_ptr;
	dest_addr += dest_offset;
	p_dest = (uint8_t *)dest_addr;
	/* Copy data from caller into destination buffer */
	memcpy(p_dest, data, size);

	return EC_SUCCESS;
}

int nvmem_move(uint32_t src_offset, uint32_t dest_offset, uint32_t size,
		enum nvmem_users user)
{
	int ret;
	uint8_t *p_src, *p_dest;
	uintptr_t base_addr;
	uint32_t s_buff_offset, d_buff_offset;

	/* Make sure that the cache buffer is active */
	ret = nvmem_lock_cache();
	if (ret) {
		nvmem_write_error = 1;
		return ret;
	}

	/* Compute partition offset for source */
	ret = nvmem_get_partition_off(user, src_offset, size, &s_buff_offset);
	if (ret != EC_SUCCESS) {
		nvmem_write_error = 1;
		return ret;
	}

	/* Compute partition offset for destination */
	ret = nvmem_get_partition_off(user, dest_offset, size, &d_buff_offset);
	if (ret != EC_SUCCESS) {
		nvmem_write_error = 1;
		return ret;
	}

	base_addr = (uintptr_t)cache.base_ptr;
	/* Create pointer to src location within partition */
	p_src = (uint8_t *)(base_addr + s_buff_offset);
	/* Create pointer to dest location within partition */
	p_dest = (uint8_t *)(base_addr + d_buff_offset);
	/* Move the data block in NvMem */
	memmove(p_dest, p_src, size);

	return EC_SUCCESS;
}

int nvmem_commit(void)
{
	int nvmem_offset;
	int new_active_partition;
	uint16_t version;
	struct nvmem_partition *p_part;

	/* Ensure that all writes/moves prior to commit call succeeded */
	if (nvmem_write_error) {
		CPRINTS("NvMem: Write Error, commit abandoned");
		/* Clear error state */
		nvmem_write_error = 0;
		nvmem_release_cache();
		return EC_ERROR_UNKNOWN;
	}
	/*
	 * All scratch buffer blocks must be written to physical flash
	 * memory. In addition, the scratch block buffer index table
	 * entries must be reset along with the index itself.
	 */

	/* Update version number */
	if (cache.base_ptr == NULL) {
		CPRINTF("%s:%d\n", __func__, __LINE__);
		return EC_ERROR_UNKNOWN;
	}
	p_part = (struct nvmem_partition *)cache.base_ptr;
	version = p_part->tag.version + 1;
	/* Check for restricted version number */
	if (version == NVMEM_VERSION_MASK)
		version = 0;
	p_part->tag.version = version;
	/* Update the sha */
	nvmem_compute_sha(&cache.base_ptr[NVMEM_SHA_SIZE],
			  NVMEM_PARTITION_SIZE - NVMEM_SHA_SIZE,
			  p_part->tag.sha,
			  NVMEM_SHA_SIZE);

	/* Toggle parition being used (always write to current spare) */
	new_active_partition = nvmem_act_partition ^ 1;
	/* Point to first block within active partition */
	nvmem_offset = nvmem_flash_offset[new_active_partition];
	/* Write partition to NvMem */

	/* Erase partition */
	if (flash_physical_erase(nvmem_offset,
				 NVMEM_PARTITION_SIZE)) {
		CPRINTF("%s:%d\n", __func__, __LINE__);
		/* Free up scratch buffers */
		nvmem_release_cache();
		return EC_ERROR_UNKNOWN;
	}
	/* Write partition */
	if (flash_physical_write(nvmem_offset,
				 NVMEM_PARTITION_SIZE,
				 cache.base_ptr)) {
		CPRINTF("%s:%d\n", __func__, __LINE__);
		/* Free up scratch buffers */
		nvmem_release_cache();
		return EC_ERROR_UNKNOWN;
	}

	/* Free up scratch buffers */
	nvmem_release_cache();
	/* Update newest partition index */
	nvmem_act_partition = new_active_partition;
	return EC_SUCCESS;
}