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Refine granularity handling in preparation of AT45DB series support

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This adds a number of new granularitie and refines the handling of
n-byte granularities by extracting the respective code into a helper
function which reduces the pain of the above significantly.

Corresponding to flashrom svn r1666.

Signed-off-by: Stefan Tauner <stefan.tauner@alumni.tuwien.ac.at>
Acked-by: Carl-Daniel Hailfinger <c-d.hailfinger.devel.2006@gmx.net>
This commit is contained in:
Stefan Tauner 2013-04-01 19:34:53 +00:00
parent 52b6e9dc54
commit 02437458a6
2 changed files with 63 additions and 25 deletions
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24
flash.h
View File

@ -59,18 +59,22 @@ enum chipbustype {
};
/*
* The following write granularities are known:
* - 1 bit: Each bit can be cleared individually.
* - 1 byte: A byte can be written once. Further writes to an already written byte cause its contents to be
* either undefined or to stay unchanged.
* - 128 bytes: If less than 128 bytes are written, the rest will be erased. Each write to a 128-byte region
* will trigger an automatic erase before anything is written. Very uncommon behaviour.
* - 256 bytes: If less than 256 bytes are written, the contents of the unwritten bytes are undefined.
* The following enum defines possible write granularities of flash chips. These tend to reflect the properties
* of the actual hardware not necesserily the write function(s) defined by the respective struct flashchip.
* The latter might (and should) be more precisely specified, e.g. they might bail out early if their execution
* would result in undefined chip contents.
*/
enum write_granularity {
write_gran_256bytes = 0, /* We assume 256 byte granularity by default. */
write_gran_1bit,
write_gran_1byte,
/* We assume 256 byte granularity by default. */
write_gran_256bytes = 0,/* If less than 256 bytes are written, the unwritten bytes are undefined. */
write_gran_1bit, /* Each bit can be cleared individually. */
write_gran_1byte, /* A byte can be written once. Further writes to an already written byte cause
* its contents to be either undefined or to stay unchanged. */
write_gran_264bytes, /* If less than 264 bytes are written, the unwritten bytes are undefined. */
write_gran_512bytes, /* If less than 512 bytes are written, the unwritten bytes are undefined. */
write_gran_528bytes, /* If less than 528 bytes are written, the unwritten bytes are undefined. */
write_gran_1024bytes, /* If less than 1024 bytes are written, the unwritten bytes are undefined. */
write_gran_1056bytes, /* If less than 1056 bytes are written, the unwritten bytes are undefined. */
};
/*

64
flashrom.c
View File

@ -688,6 +688,23 @@ out_free:
return ret;
}
/* Helper function for need_erase() that focuses on granularities of gran bytes. */
static int need_erase_gran_bytes(uint8_t *have, uint8_t *want, unsigned int len, unsigned int gran)
{
unsigned int i, j, limit;
for (j = 0; j < len / gran; j++) {
limit = min (gran, len - j * gran);
/* Are 'have' and 'want' identical? */
if (!memcmp(have + j * gran, want + j * gran, limit))
continue;
/* have needs to be in erased state. */
for (i = 0; i < limit; i++)
if (have[j * gran + i] != 0xff)
return 1;
}
return 0;
}
/*
* Check if the buffer @have can be programmed to the content of @want without
* erasing. This is only possible if all chunks of size @gran are either kept
@ -705,7 +722,7 @@ out_free:
int need_erase(uint8_t *have, uint8_t *want, unsigned int len, enum write_granularity gran)
{
int result = 0;
unsigned int i, j, limit;
unsigned int i;
switch (gran) {
case write_gran_1bit:
@ -723,20 +740,22 @@ int need_erase(uint8_t *have, uint8_t *want, unsigned int len, enum write_granul
}
break;
case write_gran_256bytes:
for (j = 0; j < len / 256; j++) {
limit = min (256, len - j * 256);
/* Are 'have' and 'want' identical? */
if (!memcmp(have + j * 256, want + j * 256, limit))
continue;
/* have needs to be in erased state. */
for (i = 0; i < limit; i++)
if (have[j * 256 + i] != 0xff) {
result = 1;
break;
}
if (result)
break;
}
result = need_erase_gran_bytes(have, want, len, 256);
break;
case write_gran_264bytes:
result = need_erase_gran_bytes(have, want, len, 264);
break;
case write_gran_512bytes:
result = need_erase_gran_bytes(have, want, len, 512);
break;
case write_gran_528bytes:
result = need_erase_gran_bytes(have, want, len, 528);
break;
case write_gran_1024bytes:
result = need_erase_gran_bytes(have, want, len, 1024);
break;
case write_gran_1056bytes:
result = need_erase_gran_bytes(have, want, len, 1056);
break;
default:
msg_cerr("%s: Unsupported granularity! Please report a bug at "
@ -784,6 +803,21 @@ static unsigned int get_next_write(uint8_t *have, uint8_t *want, unsigned int le
case write_gran_256bytes:
stride = 256;
break;
case write_gran_264bytes:
stride = 264;
break;
case write_gran_512bytes:
stride = 512;
break;
case write_gran_528bytes:
stride = 528;
break;
case write_gran_1024bytes:
stride = 1024;
break;
case write_gran_1056bytes:
stride = 1056;
break;
default:
msg_cerr("%s: Unsupported granularity! Please report a bug at "
"flashrom@flashrom.org\n", __func__);