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////////////////////////////////////////////////////////////////////////////////
//
// Filename: 	ddrsdramsim.cpp
//
// Project:	A wishbone controlled DDR3 SDRAM memory controller.
//
// Purpose:	
//
// Creator:	Dan Gisselquist, Ph.D.
//		Gisselquist Technology, LLC
//
////////////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2015-2016, Gisselquist Technology, LLC
//
// This program is free software (firmware): 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 3 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 MERCHANTIBILITY 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.  (It's in the $(ROOT)/doc directory, run make with no
// target there if the PDF file isn't present.)  If not, see
// <http://www.gnu.org/licenses/> for a copy.
//
// License:	GPL, v3, as defined and found on www.gnu.org,
//		http://www.gnu.org/licenses/gpl.html
//
//
////////////////////////////////////////////////////////////////////////////////
//
//
#include <stdio.h>
#include <assert.h>
 
const unsigned ckCL = 5,
		ckRC = 3,
		ckRFC = 320, // Clocks from refresh to activate
		nREF = 4,
		ckREFI = 1560, // 7.8us @ 200MHz = 7.8e-6 * 200e6 = 1560
		ckREFIn = nREF*ckREFI - (nREF-1) * ckRFC;
 
#include "ddrsdramsim.h"
void	BANKINFO::tick(int cmd, unsigned addr) {
	switch(cmd) {
		case DDR_PRECHARGE:
			m_state = 6;
			break;
		case DDR_ACTIVATE:
			m_state = 1;
			m_row = addr & 0x7fff;
			break;
		case DDR_READ: case DDR_WRITE:
			printf("BANK::R/W Request, m_state = %d\n", m_state);
			assert((m_state&7) == 7);
			break;
		case DDR_ZQS:
			assert((m_state&7) == 0);
			break;
		case DDR_NOOP:
			m_state <<= 1;
			m_state |= (m_state&2)>>1;
			break;
		default:
			break;
	}
}
 
int gbl_state, gbl_counts;
 
DDRSDRAMSIM::DDRSDRAMSIM(int lglen) {
	m_memlen = (1<<(lglen-2));
	m_mem = new unsigned[m_memlen];
	m_reset_state = 0;
	m_reset_counts= 0;
	m_bus = new BUSTIMESLOT[NTIMESLOTS];
	for(int i=0; i<NTIMESLOTS; i++)
		m_bus[i].m_used = 0;
	m_busloc = 0;
}
 
unsigned DDRSDRAMSIM::operator()(int reset_n, int cke,
		int csn, int rasn, int casn, int wen,
		int dqs, int dm, int odt, int busoe,
		int addr, int ba, int data) {
 
	int	cmd = (reset_n?0:32)|(cke?0:16)|(csn?8:0)
			|(rasn?4:0)|(casn?2:0)|(wen?1:0);
	if ((m_reset_state!=0)&&(reset_n==0)) {
		m_reset_state = 0;
		m_reset_counts = 0;
	} else if (m_reset_state < 16) {
		switch(m_reset_state) {
		case 0: 
			m_reset_counts++;
			if (reset_n) {
				assert(m_reset_counts > 40000);
				m_reset_counts = 0;
				m_reset_state = 1;
			} break;
		case 1:
			m_reset_counts++;
			if (cke) {
				assert(m_reset_counts > 100000);
				m_reset_counts = 0;
				m_reset_state = 2;
			} break;
		case 2:
			m_reset_counts++;
			assert(cke);
			if (cmd != DDR_NOOP) {
				assert(m_reset_counts > 147);
				m_reset_counts = 0;
				m_reset_state = 3;
				assert(cmd == DDR_MRSET);
				assert(ba == 2);
				assert(addr == 0x040);
			} break;
		case 3:
			m_reset_counts++;
			assert(cke);
			if (cmd != DDR_NOOP) {
				// assert(m_reset_counts > 3);
				m_reset_counts = 0;
				m_reset_state = 4;
				assert(cmd == DDR_MRSET);
				// assert(ba == 1);
				// assert(addr == 0x847);
			} break;
		case 4:
			m_reset_counts++;
			assert(cke);
			if (cmd != DDR_NOOP) {
				printf("DDR3-SDRAM::RESET-CMD[4]: %d:%08x[%d]@0x%04x\n", cmd, m_reset_counts, ba, addr);
				assert(m_reset_counts > 3);
				m_reset_counts = 0;
				m_reset_state = 5;
				assert(cmd == DDR_MRSET);
				assert(ba == 0);
				assert(addr == 0x210);
			} break;
		case 5:
			m_reset_counts++;
			assert(cke);
			if (cmd != DDR_NOOP) {
				printf("DDR3-SDRAM::RESET-CMD[5]: %d:%08x[%d]@0x%04x\n", cmd, m_reset_counts, ba, addr);
				assert(m_reset_counts > 11);
				m_reset_counts = 0;
				m_reset_state = 6;
				assert(cmd == DDR_ZQS);
				assert(addr == 0x400);
			} break;
		case 6:
			m_reset_counts++;
			assert(cke);
			if (cmd != DDR_NOOP) {
				printf("DDR3-SDRAM::RESET-CMD[6]: %d:%08x[%d]@0x%04x\n", cmd, m_reset_counts, ba, addr);
				assert(m_reset_counts > 512);
				m_reset_counts = 0;
				m_reset_state = 7;
				assert(cmd == DDR_PRECHARGE);
				assert(addr == 0x400);
			} break;
		case 7:
			m_reset_counts++;
			assert(cke);
			if (cmd != DDR_NOOP) {
				printf("DDR3-SDRAM::RESET-CMD[7]: %d:%08x[%d]@0x%04x\n", cmd, m_reset_counts, ba, addr);
				assert(m_reset_counts > 3);
				m_reset_counts = 0;
				m_reset_state = 8;
				assert(cmd == DDR_REFRESH);
				m_clocks_since_refresh = 0;
			} break;
		case 8:
			m_reset_counts++;
			assert(cke);
			assert(cmd == DDR_NOOP);
			if (m_reset_counts > 140) {
				m_reset_state = 16;
				printf("DDR3-SDRAM: Leaving reset state\n");
			}
			break;
		default:
			break;
		}
 
		gbl_state = m_reset_state;
		gbl_counts= m_reset_counts;
		m_nrefresh_issued = nREF;
		m_clocks_since_refresh++;
	} else if (!cke) {
		assert(0&&"Clock not enabled!");
	} else if ((cmd == DDR_REFRESH)||(m_nrefresh_issued < (int)nREF)) {
		if (DDR_REFRESH == cmd) {
			m_clocks_since_refresh = 0;
			if (m_nrefresh_issued >= (int)nREF)
				m_nrefresh_issued = 1;
			else
				m_nrefresh_issued++;
		} else {
			m_clocks_since_refresh++;
			assert(DDR_NOOP == cmd);
		}
		for(int i=0; i<NBANKS; i++)
			m_bank[i].tick(DDR_REFRESH,0);
 
		if (m_nrefresh_issued == nREF)
			printf("DDRSDRAM::Refresh cycle complete\n");
	} else {
		// In operational mode!!
 
		m_clocks_since_refresh++;
		assert(m_clocks_since_refresh < (int)ckREFIn);
		printf("Clocks to refresh should be %4d-%4d = %4d = 0x%04x\n",
			ckREFIn, m_clocks_since_refresh, 
			ckREFIn- m_clocks_since_refresh, 
			ckREFIn- m_clocks_since_refresh);
		switch(cmd) {
		case DDR_MRSET:
			assert(0&&"Modes should only be set in reset startup");
			for(int i=0; i<NBANKS; i++)
				m_bank[i].tick(DDR_MRSET,0);
			break;
		case DDR_REFRESH:
			for(int i=0; i<NBANKS; i++)
				m_bank[i].tick(DDR_REFRESH,0);
			m_clocks_since_refresh = 0;
			assert(0 && "Internal err: Refresh should be handled above");
			break;
		case DDR_PRECHARGE:
			if (addr & 0x40) {
				// Precharge all
				for(int i=0; i<NBANKS; i++)
					m_bank[i].tick(DDR_PRECHARGE,0);
			} else {
				m_bank[ba].tick(DDR_PRECHARGE,0);
				for(int i=0; i<NBANKS; i++)
					if (ba != i)
						m_bank[i].tick(DDR_NOOP,0);
			}
			break;
		case DDR_ACTIVATE:
			printf("DDRSIM::ACTIVE, clocks_since_refresh = %d >= %d\n", m_clocks_since_refresh, ckRFC);
			assert(m_clocks_since_refresh >= (int)ckRFC);
			m_bank[ba].tick(DDR_ACTIVATE,addr);
			for(int i=0; i<NBANKS; i++)
				if (i!=ba) m_bank[i].tick(DDR_NOOP,0);
			break;
		case DDR_WRITE:
			{
				// This SIM doesn't handle out of order writes
				assert((addr&7)==0);
				m_bank[ba].tick(DDR_WRITE, addr);
				for(int i=0; i<NBANKS; i++)
					if (i!=ba)m_bank[i].tick(DDR_NOOP,addr);
				unsigned caddr = m_bank[ba].m_row;
				caddr <<= 13;
				caddr |= ba;
				caddr <<= 10;
				caddr |= addr;
				caddr &= ~7;
				caddr >>= 1;
 
				printf("DDRSDRAM::WRITE ADDR = %04x|%d|%04x|%d -> %06x\n",
					m_bank[ba].m_row, ba, addr, 0, caddr);
 
				BUSTIMESLOT *tp;
				int	offset = m_busloc+ckCL+1;
 
				tp = &m_bus[(offset+0)&(NTIMESLOTS-1)];
				printf("Setting bus timeslots from (now=%d)+%d=%d to now+%d+3\n", m_busloc, ckCL,(m_busloc+ckCL)&(NTIMESLOTS-1), ckCL);
				tp->m_addr = caddr  ;
				tp->m_used = 1;
				tp->m_read = 0;
 
				tp = &m_bus[(offset+1)&(NTIMESLOTS-1)];
				tp->m_addr = caddr+1;
				tp->m_used = 1;
				tp->m_read = 0;
 
				tp = &m_bus[(offset+2)&(NTIMESLOTS-1)];
				tp->m_addr = caddr+2;
				tp->m_used = 1;
				tp->m_read = 0;
 
				tp = &m_bus[(offset+3)&(NTIMESLOTS-1)];
				tp->m_addr = caddr+3;
				tp->m_used = 1;
				tp->m_read = 0;
			} break;
		case DDR_READ:
			{
				// This SIM doesn't handle out of order reads
				assert((addr&7)==0);
				m_bank[ba].tick(DDR_READ, addr);
				for(int i=0; i<NBANKS; i++)
					if (i!=ba)m_bank[i].tick(DDR_NOOP,addr);
				unsigned caddr = m_bank[ba].m_row;
				caddr <<= 13;
				caddr |= ba;
				caddr <<= 10;
				caddr |= addr;
				caddr &= ~7;
				caddr >>= 1;
 
				BUSTIMESLOT *tp;
 
				tp = &m_bus[(m_busloc+ckCL+0)&(NTIMESLOTS-1)];
				tp->m_data = m_mem[caddr];
				tp->m_addr = caddr;
				tp->m_used = 1;
				tp->m_read = 1;
 
				tp = &m_bus[(m_busloc+ckCL+1)&(NTIMESLOTS-1)];
				tp->m_data = m_mem[caddr+1];
				tp->m_addr = caddr+1;
				tp->m_used = 1;
				tp->m_read = 1;
 
				tp = &m_bus[(m_busloc+ckCL+2)&(NTIMESLOTS-1)];
				tp->m_data = m_mem[caddr+2];
				tp->m_addr = caddr+2;
				tp->m_used = 1;
				tp->m_read = 1;
 
				tp = &m_bus[(m_busloc+ckCL+3)&(NTIMESLOTS-1)];
				tp->m_data = m_mem[caddr+3];
				tp->m_addr = caddr+3;
				tp->m_used = 1;
				tp->m_read = 1;
			} break;
		case DDR_ZQS:
			assert(0&&"Sim does not support ZQS outside of startup");
			break;
		case DDR_NOOP:
			for(int i=0; i<NBANKS; i++)
				m_bank[i].tick(DDR_NOOP,addr);
			break;
		default: // We are deselecteda
			for(int i=0; i<NBANKS; i++)
				m_bank[i].tick(DDR_NOOP,addr);
			break;
		}
	}
 
	m_busloc = (m_busloc+1)&(NTIMESLOTS-1);
 
	BUSTIMESLOT	*ts = &m_bus[m_busloc];
	if (ts->m_used) {
		printf("Current timeslot = %2d, used", m_busloc);
		if (ts->m_read)
			printf(", read");
		printf("\n");
	}
	unsigned vl = ts->m_data;
	assert( ((!ts->m_used)||(busoe))
		|| ((ts->m_used)&&(ts->m_read)));
 
	assert((!ts->m_used)||(ts->m_addr < (unsigned)m_memlen));
	if ((ts->m_used)&&(!ts->m_read)&&(!dm)) {
		printf("Setting MEM[%08x] = %08x\n", ts->m_addr, data);
		m_mem[ts->m_addr] = data;
	}
	ts->m_used = 0;
	ts->m_read = 0;
	ts->m_addr = -1;
	return (!busoe)?vl:data;
}