#pypp 0
// Iris: micro-kernel for a capability-based operating system.
// mips/nanonote/nand-boot.ccp: standalone program for booting from nand.
// Copyright 2010 Bas Wijnen <wijnen@debian.org>
//
// 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 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
// 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, see <http://www.gnu.org/licenses/>.

// The following defines are taken from mtd/nand.h in the Linux source.

asm volatile ("\t.set noreorder\n"
	"\t.text\n"
	"\t.globl __start\n"
	"\t.word ~0\n"
	"__start:\n"
	"\tbal 1f\n"
	"__hack_label:\n"
	"\tnop\n"
	"\t.word _gp\n"
	"1:\n"
	"\tlw $gp, 0($ra)\n"
	"\tla $sp, stack + 0x1000\n"
	"\tla $t9, nandboot_start\n"
	"\tjr $t9\n"
	"\tnop\n"
	"\t.set reorder")

#define __KERNEL__
#include <jz4740.hh>

// Standard NAND flash commands
#define CMD_READ0		0
#define CMD_READ1		1
#define CMD_RNDOUT		5
#define CMD_PAGEPROG		0x10
#define CMD_READOOB		0x50
#define CMD_ERASE1		0x60
#define CMD_STATUS		0x70
#define CMD_STATUS_MULTI	0x71
#define CMD_SEQIN		0x80
#define CMD_RNDIN		0x85
#define CMD_READID		0x90
#define CMD_ERASE2		0xd0
#define CMD_RESET		0xff

// Extended commands for large page devices
#define CMD_READSTART		0x30
#define CMD_RNDOUTSTART		0xE0
#define CMD_CACHEDPROG		0x15

// Status bits
#define STATUS_FAIL		0x01
#define STATUS_FAIL_N1		0x02
#define STATUS_TRUE_READY	0x20
#define STATUS_READY		0x40
#define STATUS_WP		0x80

static volatile char *command
static volatile char *address
static volatile char *data

static unsigned page_bits
static unsigned redundant_bits
static unsigned block_bits
static unsigned word_size

static void unbusy ():
	while !(gpio_get_port (2) & (1 << 30)):
		// Do nothing.
	// Delay.
	for unsigned i = 0; i < 1000; ++i:
		gpio_set (0, 0)

static void addr (unsigned d):
	unbusy ()
	*address = d
	unbusy ()

static void cmd (unsigned d):
	unbusy ()
	*command = d
	unbusy ()

static void wdata (unsigned d):
	unbusy ()
	*data = d
	unbusy ()

static unsigned rdata ():
	unbusy ()
	unsigned ret = *data
	unbusy ()
	return ret

// Reset nand controller.
static void reset ():
	unsigned base = 0xa0000000 + 0x18000000
	data = (volatile char *)base
	command = (volatile char *)(base + 0x8000)
	address = (volatile char *)(base + 0x10000)

	// Set up.
	gpio_as_nand ()
	EMC_NFCSR = EMC_NFCSR_NFE1 | EMC_NFCSR_NFCE1

	// Reset nand.
	cmd (CMD_RESET)

	cmd (CMD_READID)
	addr (0)
	unsigned d = rdata ()
	//unsigned maker = d
	d = rdata ()
	//unsigned device = d
	d = rdata ()
	//unsigned internal_chip_number = 1 << (d & 0x3)
	//unsigned cell_type = 2 << ((d >> 2) & 0x3)
	//unsigned simultaneously_programmed_pages = 1 << ((d >> 4) & 0x3)
	//bool can_interleave_program_between_chips = d & 0x40
	//bool can_cache_program = d & 0x80
	d = rdata ()
	page_bits = 10 + (d & 3)
	redundant_bits = (d & 4 ? 4 : 3)
	block_bits = 16 + ((d >> 4) & 3)
	word_size = (d & 0x40 ? 16 : 8)
	//unsigned serial_access_minimum = (d & 0x80 ? 25 : 50)
	d = rdata ()
	//unsigned num_planes = 1 << ((d >> 2) & 3) 
	//unsigned plane_bits = 26 + ((d >> 4) & 7)

// Read 512 bytes from nand and store them into buffer.  a must be aligned.
// Return value is true if the oob claims there is valid data.
static bool read (unsigned a, char *buffer):
	unsigned column = a & ((1 << page_bits) - 1)
	unsigned row = a >> page_bits
	cmd (CMD_READ0)
	addr (column)
	addr (column >> 8)
	addr (row)
	addr (row >> 8)
	addr (row >> 16)
	cmd (CMD_READSTART)
	EMC_NFECR = EMC_NFECR_ECCE | EMC_NFECR_RS | EMC_NFECR_RS_DECODING | EMC_NFECR_ERST
	for unsigned t = 0; t < 0x200; ++t:
		buffer[t] = rdata ()
	EMC_NFECR = EMC_NFECR_RS | EMC_NFECR_RS_DECODING
	char error[9]
	// Spare space (starts at 1 << page_bits)
	//  0: unused
	//  2: detect valid data (at least 1 byte == 0 means valid)
	//  5: unused
	//  6: 9-byte ecc of 1st 512 bytes
	//  15: 9-byte ecc of 2nd 512 bytes
	//  24: 9-byte ecc of 3rd 512 bytes
	//  33: 9-byte ecc of 4th 512 bytes
	//  42: unused
	//  64: end of space
	unsigned validcol = (1 << page_bits) + 2
	bool valid = false
	cmd (CMD_RNDOUT)
	addr (validcol)
	addr (validcol >> 8)
	cmd (CMD_RNDOUTSTART)
	for unsigned t = 0; t < 3; ++t:
		valid = rdata () == 0 || valid
	unsigned errcol = (1 << page_bits) + (column >> 9) * 9 + 6
	cmd (CMD_RNDOUT)
	addr (errcol)
	addr (errcol >> 8)
	cmd (CMD_RNDOUTSTART)
	for unsigned t = 0; t < 9; ++t:
		error[t] = rdata ()
	EMC_NFPAR (0) = ((unsigned *)error)[0]
	EMC_NFPAR (1) = ((unsigned *)error)[1]
	EMC_NFPAR (2) = error[9]
	EMC_NFECR = EMC_NFECR_ECCE | EMC_NFECR_RS | EMC_NFECR_RS_DECODING | EMC_NFECR_PRDY
	while !(EMC_NFINTS & EMC_NFINTS_DECF):
		// Do nothing.
	unsigned errs = (EMC_NFINTS & EMC_NFINTS_ERRCNT_MASK) >> EMC_NFINTS_ERRCNT_BIT
	for unsigned i = 0; i < errs; ++i:
		buffer[EMC_NFERR (i) >> 16] ^= EMC_NFERR (i) & 0xff

extern "C":
	void nandboot_start ():
		reset ()
		// Load contents of nand flash (from 0x4000) into 0xa0600000;
		unsigned a = 0x4000
		unsigned target = 0xa0600000
		while read (a, (char *)target):
			a += 0x200
			target += 0x200
		// Then jump to 0xa0600000.
		return ((void (*)())0xa0600000) ()

unsigned char stack[0x1000]

unsigned __gxx_personality_v0