/** @addtogroup flash_file
 *
 */

/*
 * This file is part of the libopencm3 project.
 *
 * Copyright (C) 2017 Matthew Lai @m@matthewlai.ca>
 * Copyright (C) 2010 Thomas Otto <tommi@viadmin.org>
 * Copyright (C) 2010 Mark Butler <mbutler@physics.otago.ac.nz>
 *
 * This library is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This library 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this library.  If not, see <http://www.gnu.org/licenses/>.
 */

/**@{*/

#include <libopencm3/stm32/flash.h>

/*---------------------------------------------------------------------------*/
/** @brief Set the Program Parallelism Size

Set the programming word width. Note carefully the power supply voltage
restrictions under which the different word sizes may be used. See the
programming manual for more information.
@param[in] psize The programming word width one of: @ref flash_cr_program_width
*/

static inline void flash_set_program_size(uint32_t psize)
{
	FLASH_CR &= ~(FLASH_CR_PROGRAM_MASK << FLASH_CR_PROGRAM_SHIFT);
	FLASH_CR |= psize << FLASH_CR_PROGRAM_SHIFT;
}

/*---------------------------------------------------------------------------*/
/** @brief Issue Pipeline Stall

Issue a pipeline stall to make sure all write operations completed.

RM0385: After performing a data write operation and before polling the BSY bit
to be cleared, the software can issue a DSB instruction to guarantee the 
completion of a previous data write operation.

*/

static inline void flash_pipeline_stall(void)
{
	__asm__ volatile("dsb":::"memory");
}

/*---------------------------------------------------------------------------*/
/** @brief Set the Number of Wait States

Used to match the system clock to the FLASH memory access time. See the
programming manual for more information on clock speed ranges. The latency must
be changed to the appropriate value <b>before</b> any increase in clock
speed, or <b>after</b> any decrease in clock speed.

@param[in] ws values from @ref flash_latency.
*/
void flash_set_ws(uint32_t ws)
{
	uint32_t reg32;

	reg32 = FLASH_ACR;
	reg32 &= ~(FLASH_ACR_LATENCY_MASK);
	reg32 |= ws;
	FLASH_ACR = reg32;

	/* Wait until the new wait states take effect.
	 * RM0385: Check that the new number of wait states is taken into
	 * account to access the Flash memory by reading the FLASH_ACR register.
	 */
	while ((FLASH_ACR & FLASH_ACR_LATENCY_MASK) != ws);
}

/*---------------------------------------------------------------------------*/
/** @brief Unlock the Flash Program and Erase Controller

This enables write access to the Flash memory. It is locked by default on
reset.
*/

void flash_unlock(void)
{
	/* Clear the unlock sequence state. */
	FLASH_CR |= FLASH_CR_LOCK;

	/* Authorize the FPEC access. */
	FLASH_KEYR = FLASH_KEYR_KEY1;
	FLASH_KEYR = FLASH_KEYR_KEY2;
}

/*---------------------------------------------------------------------------*/
/** @brief Lock the Flash Program and Erase Controller

Used to prevent spurious writes to FLASH.
*/

void flash_lock(void)
{
	FLASH_CR |= FLASH_CR_LOCK;
}

/*---------------------------------------------------------------------------*/
/** @brief Clear the Programming Error Status Flag

*/

void flash_clear_pgperr_flag(void)
{
	FLASH_SR |= FLASH_SR_PGPERR;
}

/*---------------------------------------------------------------------------*/
/** @brief Clear the End of Operation Status Flag

*/

void flash_clear_eop_flag(void)
{
	FLASH_SR |= FLASH_SR_EOP;
}


/*---------------------------------------------------------------------------*/
/** @brief Wait until Last Operation has Ended

This loops indefinitely until an operation (write or erase) has completed by
testing the busy flag.
*/

void flash_wait_for_last_operation(void)
{
	flash_pipeline_stall();
	while ((FLASH_SR & FLASH_SR_BSY) == FLASH_SR_BSY);
}

/*---------------------------------------------------------------------------*/
/** @brief Unlock the Option Byte Access

This enables write access to the option bytes. It is locked by default on
reset.
*/

void flash_unlock_option_bytes(void)
{
	/* Clear the unlock state. */
	FLASH_OPTCR |= FLASH_OPTCR_OPTLOCK;

	/* Unlock option bytes. */
	FLASH_OPTKEYR = FLASH_OPTKEYR_KEY1;
	FLASH_OPTKEYR = FLASH_OPTKEYR_KEY2;
}

/*---------------------------------------------------------------------------*/
/** @brief Lock the Option Byte Access

This disables write access to the option bytes. It is locked by default on
reset.
*/

void flash_lock_option_bytes(void)
{
	FLASH_OPTCR |= FLASH_OPTCR_OPTLOCK;
}

/*---------------------------------------------------------------------------*/
/** @brief Clear the Erase Sequence Error Flag

This flag is set when an erase operation is performed with control register has
not been correctly set.
*/

void flash_clear_erserr_flag(void)
{
	FLASH_SR |= FLASH_SR_ERSERR;
}

/*---------------------------------------------------------------------------*/
/** @brief Clear the Programming Alignment Error Flag

*/

void flash_clear_pgaerr_flag(void)
{
	FLASH_SR |= FLASH_SR_PGAERR;
}

/*---------------------------------------------------------------------------*/
/** @brief Clear the Write Protect Error Flag

*/

void flash_clear_wrperr_flag(void)
{
	FLASH_SR |= FLASH_SR_WRPERR;
}

/*---------------------------------------------------------------------------*/
/** @brief Enable the ART Cache

*/

void flash_art_enable(void)
{
	FLASH_ACR |= FLASH_ACR_ARTEN;
}

/*---------------------------------------------------------------------------*/
/** @brief Enable the FLASH Prefetch Buffer

This buffer is used for instruction fetches and is enabled by default after
reset.

Note carefully the clock restrictions under which the prefetch buffer may be
enabled or disabled. Changes are normally made while the clock is running in
the power-on low frequency mode before being set to a higher speed mode.
See the reference manual for details.
*/

void flash_prefetch_enable(void)
{
	FLASH_ACR |= FLASH_ACR_PRFTEN;
}

/*---------------------------------------------------------------------------*/
/** @brief Disable the FLASH Prefetch Buffer

Note carefully the clock restrictions under which the prefetch buffer may be
set to disabled. See the reference manual for details.
*/

void flash_prefetch_disable(void)
{
	FLASH_ACR &= ~FLASH_ACR_PRFTEN;
}

/*---------------------------------------------------------------------------*/
/** @brief Reset the ART Cache

The ART cache must be disabled for this to have effect.
*/

void flash_art_reset(void)
{
	FLASH_ACR |= FLASH_ACR_ARTRST;
}

/*---------------------------------------------------------------------------*/
/** @brief Clear All Status Flags

Program error, end of operation, write protect error.
*/

void flash_clear_status_flags(void)
{
	flash_clear_erserr_flag();
	flash_clear_pgaerr_flag();
	flash_clear_wrperr_flag();
	flash_clear_pgperr_flag();
	flash_clear_eop_flag();
}

/*---------------------------------------------------------------------------*/
/** @brief Erase All FLASH

This performs all operations necessary to erase all sectors in the FLASH
memory.

@param program_size: 0 (8-bit), 1 (16-bit), 2 (32-bit), 3 (64-bit)
*/

void flash_erase_all_sectors(uint32_t program_size)
{
	flash_wait_for_last_operation();
	flash_set_program_size(program_size);

	FLASH_CR |= FLASH_CR_MER;		/* Enable mass erase. */
	FLASH_CR |= FLASH_CR_STRT;		/* Trigger the erase. */

	flash_wait_for_last_operation();
	FLASH_CR &= ~FLASH_CR_MER;		/* Disable mass erase. */
}

/*---------------------------------------------------------------------------*/
/** @brief Erase a Sector of FLASH

This performs all operations necessary to erase a sector in FLASH memory.
The page should be checked to ensure that it was properly erased. A sector must
first be fully erased before attempting to program it.

See the reference manual or the FLASH programming manual for details.

@param[in] sector (0 - 11 for some parts, 0-23 on others)
@param program_size: 0 (8-bit), 1 (16-bit), 2 (32-bit), 3 (64-bit)
*/

void flash_erase_sector(uint8_t sector, uint32_t program_size)
{
	flash_wait_for_last_operation();
	flash_set_program_size(program_size);

	FLASH_CR &= ~(FLASH_CR_SNB_MASK << FLASH_CR_SNB_SHIFT);
	FLASH_CR |= (sector & FLASH_CR_SNB_MASK) << FLASH_CR_SNB_SHIFT;
	FLASH_CR |= FLASH_CR_SER;
	FLASH_CR |= FLASH_CR_STRT;

	flash_wait_for_last_operation();
	FLASH_CR &= ~FLASH_CR_SER;
	FLASH_CR &= ~(FLASH_CR_SNB_MASK << FLASH_CR_SNB_SHIFT);
}

/*---------------------------------------------------------------------------*/
/** @brief Program a 64 bit Word to FLASH

This performs all operations necessary to program a 64 bit word to FLASH memory.
The program error flag should be checked separately for the event that memory
was not properly erased.

@param[in] address Starting address in Flash.
@param[in] data Double word to write
*/

void flash_program_double_word(uint32_t address, uint64_t data)
{
	/* Ensure that all flash operations are complete. */
	flash_wait_for_last_operation();
	flash_set_program_size(FLASH_CR_PROGRAM_X64);

	/* Enable writes to flash. */
	FLASH_CR |= FLASH_CR_PG;

	/* Program the double_word. */
	MMIO64(address) = data;

	/* Wait for the write to complete. */
	flash_wait_for_last_operation();

	/* Disable writes to flash. */
	FLASH_CR &= ~FLASH_CR_PG;
}

/*---------------------------------------------------------------------------*/
/** @brief Program a 32 bit Word to FLASH

This performs all operations necessary to program a 32 bit word to FLASH memory.
The program error flag should be checked separately for the event that memory
was not properly erased.

@param[in] address Starting address in Flash.
@param[in] data word to write
*/

void flash_program_word(uint32_t address, uint32_t data)
{
	/* Ensure that all flash operations are complete. */
	flash_wait_for_last_operation();
	flash_set_program_size(FLASH_CR_PROGRAM_X32);

	/* Enable writes to flash. */
	FLASH_CR |= FLASH_CR_PG;

	/* Program the word. */
	MMIO32(address) = data;

	/* Wait for the write to complete. */
	flash_wait_for_last_operation();

	/* Disable writes to flash. */
	FLASH_CR &= ~FLASH_CR_PG;
}

/*---------------------------------------------------------------------------*/
/** @brief Program a Half Word to FLASH

This performs all operations necessary to program a 16 bit word to FLASH memory.
The program error flag should be checked separately for the event that memory
was not properly erased.

@param[in] address Starting address in Flash.
@param[in] data half word to write
*/

void flash_program_half_word(uint32_t address, uint16_t data)
{
	flash_wait_for_last_operation();
	flash_set_program_size(FLASH_CR_PROGRAM_X16);

	FLASH_CR |= FLASH_CR_PG;

	MMIO16(address) = data;

	flash_wait_for_last_operation();

	FLASH_CR &= ~FLASH_CR_PG;		/* Disable the PG bit. */
}

/*---------------------------------------------------------------------------*/
/** @brief Program an 8 bit Byte to FLASH

This performs all operations necessary to program an 8 bit byte to FLASH memory.
The program error flag should be checked separately for the event that memory
was not properly erased.

@param[in] address Starting address in Flash.
@param[in] data byte to write
*/

void flash_program_byte(uint32_t address, uint8_t data)
{
	flash_wait_for_last_operation();
	flash_set_program_size(FLASH_CR_PROGRAM_X8);

	FLASH_CR |= FLASH_CR_PG;

	MMIO8(address) = data;

	flash_wait_for_last_operation();

	FLASH_CR &= ~FLASH_CR_PG;		/* Disable the PG bit. */
}

/*---------------------------------------------------------------------------*/
/** @brief Program a Data Block to FLASH

This programs an arbitrary length data block to FLASH memory. All the addresses
written to must have been erased (by calling flash_erase_sector).
The program error flag should be checked separately for the event that memory
was not properly erased.

@param[in] address Starting address in Flash.
@param[in] data Pointer to start of data block.
@param[in] len Length of data block.
*/

void flash_program(uint32_t address, uint8_t *data, uint32_t len)
{
	/* TODO: Use dword and word size program operations where possible for
	 * turbo speed.
	 */
	uint32_t i;
	for (i = 0; i < len; i++) {
		flash_program_byte(address+i, data[i]);
	}
}

/*---------------------------------------------------------------------------*/
/** @brief Program the Option Bytes

This performs all operations necessary to program the option bytes.
The option bytes do not need to be erased first.

@param[in] data value to be programmed.
*/

void flash_program_option_bytes(uint32_t data)
{
	flash_wait_for_last_operation();

	if (FLASH_OPTCR & FLASH_OPTCR_OPTLOCK) {
		flash_unlock_option_bytes();
	}

	FLASH_OPTCR = data & ~0x3;
	FLASH_OPTCR |= FLASH_OPTCR_OPTSTRT;  /* Enable option byte prog. */
	flash_wait_for_last_operation();
}
/**@}*/