/*
 * external_mem.h
 *
 *  Created on: Nov 25, 2011
 *      Author: Doug
 *
 * Copyright (C) 2011-2012 Doug Brown
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program 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 this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 *
 */

#ifndef EXTERNAL_MEM_H_
#define EXTERNAL_MEM_H_

#include <stdint.h>
#include <stdbool.h>
#include "ports.h"

#define NUM_CHIPS		4

// Holds info about the chip (retrieved with JEDEC standards)
struct ChipID
{
	uint8_t manufacturerID;
	uint8_t deviceID;
};

// Masks for functions that want a chip...
#define IC1				(1 << 3)
#define IC2				(1 << 2)
#define IC3				(1 << 1)
#define IC4				(1 << 0)
#define ALL_CHIPS		(IC1 | IC2 | IC3 | IC4)

// Type of SIMM currently being addressed -- determines command protocol used
// to talk to the chips
typedef enum ChipType
{
	ChipType8BitData_4MBitSize, /* 512Kbit to 2Mbit flash, 8-bit */
	ChipType8Bit16BitData_16MBitSize /* 16Mbit flash, 8/16-bit in 8-bit mode */
} ChipType;

// Initializes the (bit-banged) external memory interface
void ExternalMem_Init(void);

// Sets the value outputted to the address lines
void ExternalMem_SetAddress(uint32_t address);

// Sets the value outputted to the data lines
void ExternalMem_SetData(uint32_t data);

// Sets the value outputted to the address and data lines
void ExternalMem_SetAddressAndData(uint32_t address, uint32_t data);

// Puts the data lines into input mode, for reading back stored data
void ExternalMem_SetDataAsInput(void);

// Reads back the value the chips are putting onto the data lines
uint32_t ExternalMem_ReadData(void);

// This is not the nicest-looking software engineering practice
// in the world, but it saves needlessly wasted CPU cycles
// that would be wasted in layers upon layers of abstraction
#define ExternalMem_Assert(assertMask) do { Ports_ControlOff(assertMask); } while (0)
#define ExternalMem_Deassert(assertMask) do { Ports_ControlOn(assertMask); } while (0)

// Reads a set of data from all 4 chips simultaneously
void ExternalMem_Read(uint32_t startAddress, uint32_t *buf, uint32_t len);

// Performs a single write cycle on all 4 chips simultaneously
void ExternalMem_WriteCycle(uint32_t address, uint32_t data);

// Performs a single read cycle on all 4 chips simultaneously
uint32_t ExternalMem_ReadCycle(uint32_t address);

// Does an unlock sequence on the chips requested
void ExternalMem_UnlockChips(uint8_t chipsMask);

// Identifies the chips that are currently in the SIMM
void ExternalMem_IdentifyChips(struct ChipID *chips);

// Erases the chips requested
void ExternalMem_EraseChips(uint8_t chipsMask);
bool ExternalMem_EraseSectors(uint32_t address, uint32_t length, uint8_t chipsMask);

// Writes a byte to the chips requested at the specified address
void ExternalMem_WriteByteToChips(uint32_t address, uint32_t data, uint8_t chipsMask);

// Writes a buffer to the requested chips simultaneously
// (each uint32_t contains an 8-bit portion for each chip,
// which is masked away if the chip is not requested)
// returns a mask representing the chips acting up (if requested with doVerify)
// or 0 on success (or if verification was not requested)
uint8_t ExternalMem_Write(uint32_t startAddress, uint32_t *buf, uint32_t len, uint8_t chipsMask, bool doVerify);

// Tells which flash command protocol to use
void ExternalMem_SetChipType(ChipType type);
ChipType ExternalMem_GetChipType(void);

#endif /* EXTERNAL_MEM_H_ */