[Skiboot] [RFC PATCH 1/3] libflash: first pass at improved eccmemcpy interface

[Cyril Bur]

From: Cyril Bur <cyril.bur at au1.ibm.com>

This patch is twofold, improves the memcpy to better specify that we're
reading ecc bytes and prepares for the addition of the reverse operation.

Signed-off-by: Cyril Bur <cyril.bur at au1.ibm.com>
---
 libflash/ecc.c      | 18 +++++++++---------
 libflash/ecc.h      |  8 +++++++-
 libflash/libflash.c |  4 ++--
 3 files changed, 18 insertions(+), 12 deletions(-)

diff --git a/libflash/ecc.c b/libflash/ecc.c
index 61084cc..f8fcb9f 100644
--- a/libflash/ecc.c
+++ b/libflash/ecc.c
@@ -141,10 +141,10 @@ static uint8_t eccverify(uint64_t data, uint8_t ecc)
  * @retval UE - Data is uncorrectable.
  * @retval all others - which bit was corrected.
  */
-uint8_t eccmemcpy(uint64_t *dst, uint64_t *src, uint32_t len)
+uint8_t memcpy_from_ecc(uint64_t *dst, struct ecc64 *src, uint32_t len)
 {
-	beint64_t *data;
-	uint8_t *ecc;
+	beint64_t data;
+	uint8_t ecc;
 	uint32_t i;
 	uint8_t badbit;
 
@@ -159,20 +159,20 @@ uint8_t eccmemcpy(uint64_t *dst, uint64_t *src, uint32_t len)
 	len >>= 3;
 
 	for (i = 0; i < len; i++) {
-		data = (beint64_t *)((uint8_t *)src + i * 9);
-		ecc = (uint8_t *)data + 8;
+		data = (src + i)->data;
+		ecc = (src + i)->ecc;
 
-		badbit = eccverify(be64_to_cpu(*data), *ecc);
+		badbit = eccverify(be64_to_cpu(data), ecc);
 		if (badbit == UE) {
 			FL_ERR("ECC: uncorrectable error: %016lx %02x\n",
-				(long unsigned int)be64_to_cpu(*data), *ecc);
+				(long unsigned int)be64_to_cpu(data), ecc);
 			return badbit;
 		}
-		*dst = *data;
+		*dst = data;
 		if (badbit <= UE)
 			FL_INF("ECC: correctable error: %i\n", badbit);
 		if (badbit < 64)
-			*dst = (uint64_t)cpu_to_be64(be64_to_cpu(*data) ^
+			*dst = (uint64_t)cpu_to_be64(be64_to_cpu(data) ^
 					(1ul << (63 - badbit)));
 		dst++;
 	}
diff --git a/libflash/ecc.h b/libflash/ecc.h
index 581886f..62eec54 100644
--- a/libflash/ecc.h
+++ b/libflash/ecc.h
@@ -20,6 +20,7 @@
 #define __ECC_H
 
 #include <stdint.h>
+#include <ccan/endian/endian.h>
 
 /* Bit field identifiers for syndrome calculations. */
 enum eccbitfields
@@ -36,7 +37,12 @@ enum eccbitfields
         E7 = 64         //< Error in ECC bit 7
 };
 
-extern uint8_t eccmemcpy(uint64_t *dst, uint64_t *src, uint32_t len);
+struct ecc64 {
+	beint64_t data;
+	uint8_t ecc;
+} __attribute__((__packed__));
+
+extern uint8_t memcpy_from_ecc(uint64_t *dst, struct ecc64 *src, uint32_t len);
 
 /*
  * Calculate the size of a buffer if ECC is added
diff --git a/libflash/libflash.c b/libflash/libflash.c
index 2886fc7..c2a1c69 100644
--- a/libflash/libflash.c
+++ b/libflash/libflash.c
@@ -139,7 +139,7 @@ int flash_read(struct flash_chip *c, uint32_t pos, void *buf, uint32_t len)
 int flash_read_corrected(struct flash_chip *c, uint32_t pos, void *buf,
 		uint32_t len, bool ecc)
 {
-	uint64_t *bufecc;
+	struct ecc64 *bufecc;
 	uint32_t copylen;
 	int rc;
 	uint8_t ret;
@@ -162,7 +162,7 @@ int flash_read_corrected(struct flash_chip *c, uint32_t pos, void *buf,
 			goto err;
 
 		/* Extract data from ECCed data */
-		ret = eccmemcpy(buf, bufecc, copylen);
+		ret = memcpy_from_ecc(buf, bufecc, copylen);
 		if (ret == UE) {
 			rc = FLASH_ERR_ECC_INVALID;
 			goto err;
-- 
1.9.1