On Mon, Dec 15, 2008 at 03:31:55AM +0100, andrzej zaborowski wrote:
>/ 2008/12/12 Edgar E. Iglesias <address@hidden>:/
>/ > I'm having problems with machine that uses a NAND_MFR_STMICRO 0xf1,/
>/ > recent Linux versions cannot properly read from the flash./
>/ >/
>/ > Turns out that Linux MTD recently learned howto do randomly accessed reads/
>/ > from NAND flashes. QEMU has problemns emulating these./
>/ >/
>/ > This patch fixes the problem for me but I've only tested on one flash/
>/ > model and only with Linux. I'd appreciate help with testing more machines/
>/ > with NANDs and ofcourse any comments people may have on the patch./
>/ >/
>/ > Thanks/
>/ >/
>/ > commit 68a19f4348b12f85bd5fbfd8cf7b19033e1fd784/
>/ > Author: Edgar E. Iglesias <address@hidden>/
>/ > Date: Fri Dec 12 12:48:58 2008 +0100/
>/ >/
>/ > NAND: Correct random data reads./
>/ >/
>/ > Random reading depends on having the last row/page latched and not
beeing/
>/ > clobbered between read and any following random reads./
>/ >/
>/ > Also, s->iolen must be updated when loading the io/data register with /
>/ > randomly/
>/ > accessed flash data./
>/ >/
>/ > Signed-off-by: Edgar E. Iglesias <address@hidden>/
>/ >/
>/ > diff --git a/hw/nand.c b/hw/nand.c/
>/ > index 7c9f0aa..a6f67c6 100644/
>/ > --- a/hw/nand.c/
>/ > +++ b/hw/nand.c/
>/ > @@ -212,6 +212,7 @@ void nand_reset(struct nand_flash_s *s)/
>/ >/
>/ > static void nand_command(struct nand_flash_s *s)/
>/ > {/
>/ > + unsigned int offset;/
>/ > switch (s->cmd) {/
>/ > case NAND_CMD_READ0:/
>/ > s->iolen = 0;/
>/ > @@ -233,8 +234,12 @@ static void nand_command(struct nand_flash_s *s)/
>/ > case NAND_CMD_NOSERIALREAD2:/
>/ > if (!(nand_flash_ids[s->chip_id].options & NAND_SAMSUNG_LP))/
>/ > break;/
>/ > -/
>/ > - s->blk_load(s, s->addr, s->addr & ((1 << s->addr_shift) - 1));/
>/ > + offset = s->addr & ((1 << s->addr_shift) - 1);/
>/ > + s->blk_load(s, s->addr, offset);/
>/ > + if (s->gnd)/
>/ > + s->iolen = (1 << s->page_shift) - offset;/
>/ > + else/
>/ > + s->iolen = (1 << s->page_shift) + (1 << s->oob_shift) -
offset;/
>/ > break;/
>/ >/
>/ > case NAND_CMD_RESET:/
>/ > @@ -380,12 +385,15 @@ void nand_setio(struct nand_flash_s *s, uint8_t
value)/
>/ >/
>/ > if (s->cmd != NAND_CMD_RANDOMREAD2) {/
>/ > s->addrlen = 0;/
>/ > - s->addr = 0;/
>/ > }/
>/ > }/
>/ >/
>/ > if (s->ale) {/
>/ > - s->addr |= value << (s->addrlen * 8);/
>/ > + unsigned int shift = s->addrlen * 8;/
>/ > + unsigned int mask = ~(0xff << shift);/
>/ > + unsigned int v = value << shift;/
>/ > +/
>/ > + s->addr = (s->addr & mask) | v;/
>/ > s->addrlen ++;/
>/ >/
>/ > if (s->addrlen == 1 && s->cmd == NAND_CMD_READID)/
>/ > @@ -680,9 +688,6 @@ static void glue(nand_blk_load_, PAGE_SIZE)(struct /
>/ > nand_flash_s *s,/
>/ > offset, PAGE_SIZE + OOB_SIZE - offset);/
>/ > s->ioaddr = s->io;/
>/ > }/
>/ > -/
>/ > - s->addr &= PAGE_SIZE - 1;/
>/ > - s->addr += PAGE_SIZE;/
>/ /
>/ Won't that break sequential reading? I think the other modifications/
I found specs for a flash with sequential page-crossing reads. My
code does not handle that but neither does current svn AFAICT. The
masking is wrong, we'll always end up at page 1.
>/ should also be conditional on the command being RANDOMREAD./
>/ /
>/ BTW, do you happen to know what the difference is between RANDOMREAD2/
>/ and NOSERIALREAD2? I basically added those commands because various/
AFAIK noserial reads are for preparing copyback writes. Random reads are
for random access within the page register.
I'll try to fix and test the page-crossing seqreads.
Thanks alot for the comments.