[Skiboot] [RFC PATCH 3/3] libflash: add flash_erase_corrected() to set ECC bytes in erased areas

[Cyril Bur]

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

Signed-off-by: Cyril Bur <cyril.bur at au1.ibm.com>
---
 libflash/libflash.c | 32 ++++++++++++++++++++++++++++++++
 libflash/libflash.h |  1 +
 2 files changed, 33 insertions(+)

diff --git a/libflash/libflash.c b/libflash/libflash.c
index cae62ec..84a78f6 100644
--- a/libflash/libflash.c
+++ b/libflash/libflash.c
@@ -309,6 +309,38 @@ int flash_erase(struct flash_chip *c, uint32_t dst, uint32_t size)
 	return 0;
 }
 
+int flash_erase_corrected(struct flash_chip *c, uint32_t dst, uint32_t size, bool ecc)
+{
+
+	int rc = flash_erase(c, dst, size);
+
+	if (rc == 0 && ecc) {
+		uint32_t i;
+		uint8_t zero = 0;
+
+		/*
+		 * We have just erased this region which means it will be all FF.
+		 * The ECC byte for that is 00 so the easiest way to deal is just to
+		 * write 00 every 9th byte.
+		 * Really should optimise this.
+		 */
+
+		/* Align dst, probably already is but best to be sure */
+		if (dst & 0x7) {
+			dst &= ~0x7UL;
+			dst += 8;
+		}
+
+		i = 9;
+		while (rc == 0 && i < size) {
+			rc = flash_write(c, dst + i, &zero, 1, 0);
+			i += 9;
+		}
+	}
+
+	return rc;
+}
+
 int flash_erase_chip(struct flash_chip *c)
 {
 	struct spi_flash_ctrl *ct = c->ctrl;
diff --git a/libflash/libflash.h b/libflash/libflash.h
index 51584da..f7ca205 100644
--- a/libflash/libflash.h
+++ b/libflash/libflash.h
@@ -74,6 +74,7 @@ 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);
 int flash_erase(struct flash_chip *c, uint32_t dst, uint32_t size);
+int flash_erase_corrected(struct flash_chip *c, uint32_t dst, uint32_t size, bool ecc);
 int flash_write(struct flash_chip *c, uint32_t dst, const void *src,
 		uint32_t size, bool verify);
 int flash_write_corrected(struct flash_chip *c, uint32_t dst, const void *src,
-- 
1.9.1