2013/3/1 Peter Maydell <peter.mayd...@linaro.org>: > On 27 February 2013 07:15, Kuo-Jung Su <dant...@gmail.com> wrote: >> From: Kuo-Jung Su <dant...@faraday-tech.com> > > Your subject line could be made a little more specific, like this: > "hw/nand.c: correct the sense of the BUSY/READY status bit". >
Got it, thanks >> The BIT6 of Status Register(SR): >> >> SR[6] behaves the same as R/B# pin >> SR[6] = 0 indicates the device is busy; >> SR[6] = 1 means the device is ready >> >> Some NAND flash controller (i.e. ftnandc021) relies on the SR[6] >> to determine if the NAND flash erase/program is success or error timeout. >> >> P.S: >> The exmaple NAND flash datasheet could be found at following link: >> http://www.mxic.com.tw/QuickPlace/hq/PageLibrary4825740B00298A3B.nsf/h_Index/8FEA549237D2F7674825795800104C26/$File/MX30LF1G08AA,%203V,%201Gb,%20v1.1.pdf >> >> Signed-off-by: Kuo-Jung Su <dant...@faraday-tech.com> >> --- >> hw/nand.c | 20 +++++++++++++++++--- >> 1 file changed, 17 insertions(+), 3 deletions(-) >> >> diff --git a/hw/nand.c b/hw/nand.c >> index 4a71265..7f40ebf 100644 >> --- a/hw/nand.c >> +++ b/hw/nand.c >> @@ -46,7 +46,7 @@ >> # define NAND_IOSTATUS_PLANE1 (1 << 2) >> # define NAND_IOSTATUS_PLANE2 (1 << 3) >> # define NAND_IOSTATUS_PLANE3 (1 << 4) >> -# define NAND_IOSTATUS_BUSY (1 << 6) >> +# define NAND_IOSTATUS_READY (1 << 6) >> # define NAND_IOSTATUS_UNPROTCT (1 << 7) >> >> # define MAX_PAGE 0x800 >> @@ -231,6 +231,7 @@ static void nand_reset(DeviceState *dev) >> s->iolen = 0; >> s->offset = 0; >> s->status &= NAND_IOSTATUS_UNPROTCT; >> + s->status |= NAND_IOSTATUS_READY; >> } > > These two parts look good. > >> >> static inline void nand_pushio_byte(NANDFlashState *s, uint8_t value) >> @@ -647,6 +648,8 @@ static void glue(nand_blk_write_, >> PAGE_SIZE)(NANDFlashState *s) >> if (PAGE(s->addr) >= s->pages) >> return; >> >> + s->status &= ~NAND_IOSTATUS_READY; >> + >> if (!s->bdrv) { >> mem_and(s->storage + PAGE_START(s->addr) + (s->addr & PAGE_MASK) + >> s->offset, s->io, s->iolen); >> @@ -656,7 +659,7 @@ static void glue(nand_blk_write_, >> PAGE_SIZE)(NANDFlashState *s) >> soff = SECTOR_OFFSET(s->addr); >> if (bdrv_read(s->bdrv, sector, iobuf, PAGE_SECTORS) < 0) { >> printf("%s: read error in sector %" PRIu64 "\n", __func__, >> sector); >> - return; >> + goto blkw_out; >> } >> >> mem_and(iobuf + (soff | off), s->io, MIN(s->iolen, PAGE_SIZE - >> off)); >> @@ -675,7 +678,7 @@ static void glue(nand_blk_write_, >> PAGE_SIZE)(NANDFlashState *s) >> soff = off & 0x1ff; >> if (bdrv_read(s->bdrv, sector, iobuf, PAGE_SECTORS + 2) < 0) { >> printf("%s: read error in sector %" PRIu64 "\n", __func__, >> sector); >> - return; >> + goto blkw_out; >> } >> >> mem_and(iobuf + soff, s->io, s->iolen); >> @@ -685,6 +688,9 @@ static void glue(nand_blk_write_, >> PAGE_SIZE)(NANDFlashState *s) >> } >> } >> s->offset = 0; >> + >> +blkw_out: >> + s->status |= NAND_IOSTATUS_READY; >> } > > How is it ever possible for a guest to observe the status register > in the state where the READY bit is cleared? There's no point in > clearing the bit on entry to this function and setting it again > on every exit path when nobody will ever read the status register > while we're inside the function. (Same comments apply for read > and erase.) > Got it, thanks. I'll remove the code for clear/set SR[6] from the read/erase/write functions. > thanks > -- PMM -- Best wishes, Kuo-Jung Su
