Change in flashrom[master]: [v4, 1/6] Add support for selecting the erased bit value with a flag

[Mike Banon (Code Review)]

Mike Banon has uploaded this change for review. ( https://review.coreboot.org/23258

Change subject: [v4,1/6] Add support for selecting the erased bit value with a flag
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[v4,1/6] Add support for selecting the erased bit value with a flag

Most flash chips are erased to ones and programmed to zeros. However, some
other chips, such as the ENE KB9012 internal flash, work the opposite way.

Original patch has been created by Paul Kocialkowski, the previous version:
http://patchwork.coreboot.org/patch/4412/
Now it has been ported to the latest source code of flashrom master branch

Change-Id: Ia7b0de8568e31f9bf263ba0ad6b051e837477b6b
Signed-off-by: Mike Banon 
---
M flash.h
M flashrom.c
2 files changed, 24 insertions(+), 15 deletions(-)

git pull ssh://review.coreboot.org:29418/flashrom refs/changes/58/23258/1

diff --git a/flash.h b/flash.h
index d31b256..a3aebc5 100644
--- a/flash.h
+++ b/flash.h
@@ -130,6 +130,13 @@
 #define FEATURE_4BA_NATIVE	(FEATURE_4BA_READ | FEATURE_4BA_FAST_READ | FEATURE_4BA_WRITE)
 #define FEATURE_4BA		(FEATURE_4BA_ENTER | FEATURE_4BA_EXT_ADDR | FEATURE_4BA_NATIVE)
 #define FEATURE_4BA_WREN	(FEATURE_4BA_ENTER_WREN | FEATURE_4BA_EXT_ADDR | FEATURE_4BA_NATIVE)
+/*
+ * Most flash chips are erased to ones and programmed to zeros. However, some
+ * other flash chips, such as the ENE KB9012 internal flash, work the opposite way.
+ */
+#define FEATURE_ERASED_ZERO	(1 << 16)
+
+#define ERASED_VALUE(flash)	(((flash)->chip->feature_bits & FEATURE_ERASED_ZERO) ? 0x00 : 0xff)

enum test_state {
    OK = 0,
@@ -298,7 +305,7 @@
 int read_flash_to_file(struct flashctx *flash, const char *filename);
 char *extract_param(const char *const *haystack, const char *needle, const char *delim);
 int verify_range(struct flashctx *flash, const uint8_t *cmpbuf, unsigned int start, unsigned int len);
-int need_erase(const uint8_t *have, const uint8_t *want, unsigned int len, enum write_granularity gran);
+int need_erase(const uint8_t *have, const uint8_t *want, unsigned int len, enum write_granularity gran, const uint8_t erased_value);
 void print_version(void);
 void print_buildinfo(void);
 void print_banner(void);
diff --git a/flashrom.c b/flashrom.c
index ac987fd..361a44f 100644
--- a/flashrom.c
+++ b/flashrom.c
@@ -700,12 +700,13 @@
 {
    int ret;
    uint8_t *cmpbuf = malloc(len);
+	const uint8_t erased_value = ERASED_VALUE(flash);

if (!cmpbuf) {
    	msg_gerr("Could not allocate memory!\n");
    	exit(1);
    }
-	memset(cmpbuf, 0xff, len);
+	memset(cmpbuf, erased_value, len);
    ret = verify_range(flash, cmpbuf, start, len);
    free(cmpbuf);
    return ret;
@@ -758,7 +759,7 @@
 }

/* Helper function for need_erase() that focuses on granularities of gran bytes. */
-static int need_erase_gran_bytes(const uint8_t *have, const uint8_t *want, unsigned int len, unsigned int gran)
+static int need_erase_gran_bytes(const uint8_t *have, const uint8_t *want, unsigned int len, unsigned int gran, const uint8_t erased_value)
 {
    unsigned int i, j, limit;
    for (j = 0; j < len / gran; j++) {
@@ -768,7 +769,7 @@
    		continue;
    	/* have needs to be in erased state. */
    	for (i = 0; i < limit; i++)
-			if (have[j * gran + i] != 0xff)
+			if (have[j * gran + i] != erased_value)
    			return 1;
    }
    return 0;
@@ -788,7 +789,7 @@
  * @gran	write granularity (enum, not count)
  * @return      0 if no erase is needed, 1 otherwise
  */
-int need_erase(const uint8_t *have, const uint8_t *want, unsigned int len, enum write_granularity gran)
+int need_erase(const uint8_t *have, const uint8_t *want, unsigned int len, enum write_granularity gran, const uint8_t erased_value)
 {
    int result = 0;
    unsigned int i;
@@ -803,31 +804,31 @@
    	break;
    case write_gran_1byte:
    	for (i = 0; i < len; i++)
-			if ((have[i] != want[i]) && (have[i] != 0xff)) {
+			if ((have[i] != want[i]) && (have[i] != erased_value)) {
    			result = 1;
    			break;
    		}
    	break;
    case write_gran_128bytes:
-		result = need_erase_gran_bytes(have, want, len, 128);
+		result = need_erase_gran_bytes(have, want, len, 128, erased_value);
    	break;
    case write_gran_256bytes:
-		result = need_erase_gran_bytes(have, want, len, 256);
+		result = need_erase_gran_bytes(have, want, len, 256, erased_value);
    	break;
    case write_gran_264bytes:
-		result = need_erase_gran_bytes(have, want, len, 264);
+		result = need_erase_gran_bytes(have, want, len, 264, erased_value);
    	break;
    case write_gran_512bytes:
-		result = need_erase_gran_bytes(have, want, len, 512);
+		result = need_erase_gran_bytes(have, want, len, 512, erased_value);
    	break;
    case write_gran_528bytes:
-		result = need_erase_gran_bytes(have, want, len, 528);
+		result = need_erase_gran_bytes(have, want, len, 528, erased_value);
    	break;
    case write_gran_1024bytes:
-		result = need_erase_gran_bytes(have, want, len, 1024);
+		result = need_erase_gran_bytes(have, want, len, 1024, erased_value);
    	break;
    case write_gran_1056bytes:
-		result = need_erase_gran_bytes(have, want, len, 1056);
+		result = need_erase_gran_bytes(have, want, len, 1056, erased_value);
    	break;
    case write_gran_1byte_implicit_erase:
    	/* Do not erase, handle content changes from anything->0xff by writing 0xff. */
@@ -1769,11 +1770,12 @@
    ret = 1;
    bool skipped = true;
    uint8_t *const curcontents = info->curcontents + info->erase_start;
-	if (need_erase(curcontents, newcontents, erase_len, flashctx->chip->gran)) {
+	const uint8_t erased_value = ERASED_VALUE(flashctx);
+	if (need_erase(curcontents, newcontents, erase_len, flashctx->chip->gran, erased_value)) {
    	if (erase_block(flashctx, info, erasefn))
    		goto _free_ret;
    	/* Erase was successful. Adjust curcontents. */
-		memset(curcontents, 0xff, erase_len);
+		memset(curcontents, erased_value, erase_len);
    	skipped = false;
    }