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/*
* SPL driver for Diskonchip G4 nand flash
*
* Copyright (C) 2013 Mike Dunn <mikedunn@newsguy.com>
*
* SPDX-License-Identifier: GPL-2.0+
*
* This driver basically mimics the load functionality of a typical IPL (initial
* program loader) resident in the 2k NOR-like region of the docg4 that is
* mapped to the reset vector. It allows the u-boot SPL to continue loading if
* the IPL loads a fixed number of flash blocks that is insufficient to contain
* the entire u-boot image. In this case, a concatenated spl + u-boot image is
* written at the flash offset from which the IPL loads an image, and when the
* IPL jumps to the SPL, the SPL resumes loading where the IPL left off. See
* the palmtreo680 for an example.
*
* This driver assumes that the data was written to the flash using the device's
* "reliable" mode, and also assumes that each 512 byte page is stored
* redundantly in the subsequent page. This storage format is likely to be used
* by all boards that boot from the docg4. The format compensates for the lack
* of ecc in the IPL.
*
* Reliable mode reduces the capacity of a block by half, and the redundant
* pages reduce it by half again. As a result, the normal 256k capacity of a
* block is reduced to 64k for the purposes of the IPL/SPL.
*/
#include <asm/io.h>
#include <linux/mtd/docg4.h>
/* forward declarations */
static inline void write_nop(void __iomem *docptr);
static int poll_status(void __iomem *docptr);
static void write_addr(void __iomem *docptr, uint32_t docg4_addr);
static void address_sequence(unsigned int g4_page, unsigned int g4_index,
void __iomem *docptr);
static int docg4_load_block_reliable(uint32_t flash_offset, void *dest_addr);
int nand_spl_load_image(uint32_t offs, unsigned int size, void *dst)
{
void *load_addr = dst;
uint32_t flash_offset = offs;
const unsigned int block_count =
(size + DOCG4_BLOCK_CAPACITY_SPL - 1)
/ DOCG4_BLOCK_CAPACITY_SPL;
int i;
for (i = 0; i < block_count; i++) {
int ret = docg4_load_block_reliable(flash_offset, load_addr);
if (ret)
return ret;
load_addr += DOCG4_BLOCK_CAPACITY_SPL;
flash_offset += DOCG4_BLOCK_SIZE;
}
return 0;
}
static inline void write_nop(void __iomem *docptr)
{
writew(0, docptr + DOC_NOP);
}
static int poll_status(void __iomem *docptr)
{
/*
* Busy-wait for the FLASHREADY bit to be set in the FLASHCONTROL
* register. Operations known to take a long time (e.g., block erase)
* should sleep for a while before calling this.
*/
uint8_t flash_status;
/* hardware quirk requires reading twice initially */
flash_status = readb(docptr + DOC_FLASHCONTROL);
do {
flash_status = readb(docptr + DOC_FLASHCONTROL);
} while (!(flash_status & DOC_CTRL_FLASHREADY));
return 0;
}
static void write_addr(void __iomem *docptr, uint32_t docg4_addr)
{
/* write the four address bytes packed in docg4_addr to the device */
writeb(docg4_addr & 0xff, docptr + DOC_FLASHADDRESS);
docg4_addr >>= 8;
writeb(docg4_addr & 0xff, docptr + DOC_FLASHADDRESS);
docg4_addr >>= 8;
writeb(docg4_addr & 0xff, docptr + DOC_FLASHADDRESS);
docg4_addr >>= 8;
writeb(docg4_addr & 0xff, docptr + DOC_FLASHADDRESS);
}
static void address_sequence(unsigned int g4_page, unsigned int g4_index,
void __iomem *docptr)
{
writew(DOCG4_SEQ_PAGE_READ, docptr + DOC_FLASHSEQUENCE);
writew(DOCG4_CMD_PAGE_READ, docptr + DOC_FLASHCOMMAND);
write_nop(docptr);
write_addr(docptr, ((uint32_t)g4_page << 16) | g4_index);
write_nop(docptr);
}
static int docg4_load_block_reliable(uint32_t flash_offset, void *dest_addr)
{
void __iomem *docptr = (void *)CONFIG_SYS_NAND_BASE;
unsigned int g4_page = flash_offset >> 11; /* 2k page */
const unsigned int last_g4_page = g4_page + 0x80; /* last in block */
int g4_index = 0;
uint16_t flash_status;
uint16_t *buf;
/* flash_offset must be aligned to the start of a block */
if (flash_offset & 0x3ffff)
return -1;
writew(DOC_SEQ_RESET, docptr + DOC_FLASHSEQUENCE);
writew(DOC_CMD_RESET, docptr + DOC_FLASHCOMMAND);
write_nop(docptr);
write_nop(docptr);
poll_status(docptr);
write_nop(docptr);
writew(0x45, docptr + DOC_FLASHSEQUENCE);
writew(0xa3, docptr + DOC_FLASHCOMMAND);
write_nop(docptr);
writew(0x22, docptr + DOC_FLASHCOMMAND);
write_nop(docptr);
/* read 1st 4 oob bytes of first subpage of block */
address_sequence(g4_page, 0x0100, docptr); /* index at oob */
write_nop(docptr);
flash_status = readw(docptr + DOC_FLASHCONTROL);
flash_status = readw(docptr + DOC_FLASHCONTROL);
if (flash_status & 0x06) /* sequence or protection errors */
return -1;
writew(DOCG4_CMD_READ2, docptr + DOC_FLASHCOMMAND);
write_nop(docptr);
write_nop(docptr);
poll_status(docptr);
writew(DOC_ECCCONF0_READ_MODE | 4, docptr + DOC_ECCCONF0);
write_nop(docptr);
write_nop(docptr);
write_nop(docptr);
write_nop(docptr);
write_nop(docptr);
/*
* Here we read the first four oob bytes of the first page of the block.
* The IPL on the palmtreo680 requires that this contain a 32 bit magic
* number, or the load aborts. We'll ignore it.
*/
readw(docptr + 0x103c); /* hw quirk; 1st read discarded */
readw(docptr + 0x103c); /* lower 16 bits of magic number */
readw(docptr + DOCG4_MYSTERY_REG); /* upper 16 bits of magic number */
writew(0, docptr + DOC_DATAEND);
write_nop(docptr);
write_nop(docptr);
/* load contents of block to memory */
buf = (uint16_t *)dest_addr;
do {
int i;
address_sequence(g4_page, g4_index, docptr);
writew(DOCG4_CMD_READ2,
docptr + DOC_FLASHCOMMAND);
write_nop(docptr);
write_nop(docptr);
poll_status(docptr);
writew(DOC_ECCCONF0_READ_MODE |
DOC_ECCCONF0_ECC_ENABLE |
DOCG4_BCH_SIZE,
docptr + DOC_ECCCONF0);
write_nop(docptr);
write_nop(docptr);
write_nop(docptr);
write_nop(docptr);
write_nop(docptr);
/* read the 512 bytes of page data, 2 bytes at a time */
readw(docptr + 0x103c); /* hw quirk */
for (i = 0; i < 256; i++)
*buf++ = readw(docptr + 0x103c);
/* read oob, but discard it */
for (i = 0; i < 7; i++)
readw(docptr + 0x103c);
readw(docptr + DOCG4_OOB_6_7);
readw(docptr + DOCG4_OOB_6_7);
writew(0, docptr + DOC_DATAEND);
write_nop(docptr);
write_nop(docptr);
if (!(g4_index & 0x100)) {
/* not redundant subpage read; check for ecc error */
write_nop(docptr);
flash_status = readw(docptr + DOC_ECCCONF1);
flash_status = readw(docptr + DOC_ECCCONF1);
if (flash_status & 0x80) { /* ecc error */
g4_index += 0x108; /* read redundant subpage */
buf -= 256; /* back up ram ptr */
continue;
} else /* no ecc error */
g4_index += 0x210; /* skip redundant subpage */
} else /* redundant page was just read; skip ecc error check */
g4_index += 0x108;
if (g4_index == 0x420) { /* finished with 2k page */
g4_index = 0;
g4_page += 2; /* odd-numbered 2k pages skipped */
}
} while (g4_page != last_g4_page); /* while still on same block */
return 0;
}
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