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mtd: cfi_cmdset_0002: Micron M29EW bugfixes as per TN-13-07

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Fix the following issues with Micron's (formerly Numonyx)
M29EW NOR flash chips, as documented on TN-13-07:
- Correcting Erase Suspend Hang Ups (page 20)
- Resolving the Delay After Resume Issue (page 22)

Signed-off-by: Gerlando Falauto <gerlando.falauto@keymile.com>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
This commit is contained in:
Gerlando Falauto 2012-07-03 09:09:47 +02:00 committed by David Woodhouse
parent 4d363b5518
commit 4209628843
1 changed files with 67 additions and 0 deletions
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67
drivers/mtd/chips/cfi_cmdset_0002.c
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@ -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;