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Modify the spi flash driver to allow smaller read IO sizes, but enforce

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the larger, aligned write+erase sizes the driver currently implements.

This preserves write behaviour but makes the flash driver usable for things
like a read-only FFS or a geom_uzip/geom_compress .

Note that since GEOM will now return the sector size as being smaller,
writes of sector size/alignment will now fail with an EIO. Code which
writes to the flash device will have to be (for now) manually taught
about the flash write blocksize.
This commit is contained in:
Adrian Chadd 2011-02-16 20:07:44 +00:00
parent 33c45e47f4
commit 917721a495
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=218747
1 changed files with 18 additions and 17 deletions
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35
sys/dev/flash/mx25l.c
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@ -49,6 +49,13 @@ __FBSDID("$FreeBSD$");
#define FL_ERASE_4K 0x01
#define FL_ERASE_32K 0x02
/*
* Define the sectorsize to be a smaller size rather than the flash
* sector size. Trying to run FFS off of a 64k flash sector size
* results in a completely un-usable system.
*/
#define MX25L_SECTORSIZE 512
struct mx25l_flash_ident
{
const char *name;
@ -231,15 +238,11 @@ mx25l_write(device_t dev, off_t offset, caddr_t data, off_t count)
write_offset = offset;
/*
* Sanity checks
* Use the erase sectorsize here since blocks are fully erased
* first before they're written to.
*/
KASSERT(count % sc->sc_sectorsize == 0,
("count for BIO_WRITE is not sector size (%d bytes) aligned",
sc->sc_sectorsize));
KASSERT(offset % sc->sc_sectorsize == 0,
("offset for BIO_WRITE is not sector size (%d bytes) aligned",
sc->sc_sectorsize));
if (count % sc->sc_sectorsize != 0 || offset % sc->sc_sectorsize != 0)
return (EIO);
/*
* Assume here that we write per-sector only
@ -308,15 +311,13 @@ mx25l_read(device_t dev, off_t offset, caddr_t data, off_t count)
sc = device_get_softc(dev);
/*
* Sanity checks
* Enforce the disk read sectorsize not the erase sectorsize.
* In this way, smaller read IO is possible,dramatically
* speeding up filesystem/geom_compress access.
*/
KASSERT(count % sc->sc_sectorsize == 0,
("count for BIO_READ is not sector size (%d bytes) aligned",
sc->sc_sectorsize));
KASSERT(offset % sc->sc_sectorsize == 0,
("offset for BIO_READ is not sector size (%d bytes) aligned",
sc->sc_sectorsize));
if (count % sc->sc_disk->d_sectorsize != 0
|| offset % sc->sc_disk->d_sectorsize != 0)
return (EIO);
txBuf[0] = CMD_FAST_READ;
cmd.tx_cmd_sz = 5;
@ -371,7 +372,7 @@ mx25l_attach(device_t dev)
sc->sc_disk->d_name = "flash/spi";
sc->sc_disk->d_drv1 = sc;
sc->sc_disk->d_maxsize = DFLTPHYS;
sc->sc_disk->d_sectorsize = ident->sectorsize;
sc->sc_disk->d_sectorsize = MX25L_SECTORSIZE;
sc->sc_disk->d_mediasize = ident->sectorsize * ident->sectorcount;
sc->sc_disk->d_unit = device_get_unit(sc->sc_dev);
sc->sc_disk->d_dump = NULL; /* NB: no dumps */