diff options
| -rw-r--r-- | drivers/mtd/chips/cfi_cmdset_0002.c | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c index 22d0493a026f..5ff5c4a16943 100644 --- a/drivers/mtd/chips/cfi_cmdset_0002.c +++ b/drivers/mtd/chips/cfi_cmdset_0002.c @@ -431,6 +431,68 @@ static void cfi_fixup_major_minor(struct cfi_private *cfi, } } +static int is_m29ew(struct cfi_private *cfi) +{ + if (cfi->mfr == CFI_MFR_INTEL && + ((cfi->device_type == CFI_DEVICETYPE_X8 && (cfi->id & 0xff) == 0x7e) || + (cfi->device_type == CFI_DEVICETYPE_X16 && cfi->id == 0x227e))) + return 1; + return 0; +} + +/* + * From TN-13-07: Patching the Linux Kernel and U-Boot for M29 Flash, page 20: + * Some revisions of the M29EW suffer from erase suspend hang ups. In + * particular, it can occur when the sequence + * Erase Confirm -> Suspend -> Program -> Resume + * causes a lockup due to internal timing issues. The consequence is that the + * erase cannot be resumed without inserting a dummy command after programming + * and prior to resuming. [...] The work-around is to issue a dummy write cycle + * that writes an F0 command code before the RESUME command. + */ +static void cfi_fixup_m29ew_erase_suspend(struct map_info *map, + unsigned long adr) +{ + struct cfi_private *cfi = map->fldrv_priv; + /* before resume, insert a dummy 0xF0 cycle for Micron M29EW devices */ + if (is_m29ew(cfi)) + map_write(map, CMD(0xF0), adr); +} + +/* + * From TN-13-07: Patching the Linux Kernel and U-Boot for M29 Flash, page 22: + * + * Some revisions of the M29EW (for example, A1 and A2 step revisions) + * are affected by a problem that could cause a hang up when an ERASE SUSPEND + * command is issued after an ERASE RESUME operation without waiting for a + * minimum delay. The result is that once the ERASE seems to be completed + * (no bits are toggling), the contents of the Flash memory block on which + * the erase was ongoing could be inconsistent with the expected values + * (typically, the array value is stuck to the 0xC0, 0xC4, 0x80, or 0x84 + * values), causing a consequent failure of the ERASE operation. + * The occurrence of this issue could be high, especially when file system + * operations on the Flash are intensive. As a result, it is recommended + * that a patch be applied. Intensive file system operations can cause many + * calls to the garbage routine to free Flash space (also by erasing physical + * Flash blocks) and as a result, many consecutive SUSPEND and RESUME + * commands can occur. The problem disappears when a delay is inserted after + * the RESUME command by using the udelay() function available in Linux. + * The DELAY value must be tuned based on the customer's platform. + * The maximum value that fixes the problem in all cases is 500us. + * But, in our experience, a delay of 30 µs to 50 µs is sufficient + * in most cases. + * We have chosen 500µs because this latency is acceptable. + */ +static void cfi_fixup_m29ew_delay_after_resume(struct cfi_private *cfi) +{ + /* + * Resolving the Delay After Resume Issue see Micron TN-13-07 + * Worst case delay must be 500µs but 30-50µs should be ok as well + */ + if (is_m29ew(cfi)) + cfi_udelay(500); +} + struct mtd_info *cfi_cmdset_0002(struct map_info *map, int primary) { struct cfi_private *cfi = map->fldrv_priv; @@ -776,7 +838,10 @@ static void put_chip(struct map_info *map, struct flchip *chip, unsigned long ad switch(chip->oldstate) { case FL_ERASING: + cfi_fixup_m29ew_erase_suspend(map, + chip->in_progress_block_addr); map_write(map, cfi->sector_erase_cmd, chip->in_progress_block_addr); + cfi_fixup_m29ew_delay_after_resume(cfi); chip->oldstate = FL_READY; chip->state = FL_ERASING; break; @@ -916,6 +981,8 @@ static void __xipram xip_udelay(struct map_info *map, struct flchip *chip, /* Disallow XIP again */ local_irq_disable(); + /* Correct Erase Suspend Hangups for M29EW */ + cfi_fixup_m29ew_erase_suspend(map, adr); /* Resume the write or erase operation */ map_write(map, cfi->sector_erase_cmd, adr); chip->state = oldstate; |