[Skiboot] [PATCH 4/5] libflash/mbox-flash: Implement MARK_WRITE_ERASED mbox call

[Cyril Bur]

Version two of the mbox-flash protocol defines a new command:
MARK_WRITE_ERASED.

This command provides a simple way to mark a region of flash as all 0xff
without the need to go and write all 0xff. This is an optimisation as
there is no need for an erase before a write, it is the responsibility of
the BMC to deal with the flash correctly, however in v1 it was ambiguous
what a client should do if the flash should be erased but not actually
written to. This allows of a optimal path to resolve this problem.

Signed-off-by: Cyril Bur <cyril.bur at au1.ibm.com>
---
 libflash/mbox-flash.c | 64 ++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 61 insertions(+), 3 deletions(-)

diff --git a/libflash/mbox-flash.c b/libflash/mbox-flash.c
index 3dfcebe9..5d29215c 100644
--- a/libflash/mbox-flash.c
+++ b/libflash/mbox-flash.c
@@ -761,7 +761,64 @@ out:
 	return rc;
 }
 
-static int mbox_flash_erase(struct blocklevel_device *bl __unused,
+static int mbox_flash_erase_v2(struct blocklevel_device *bl, uint64_t pos,
+		uint64_t len)
+{
+	uint64_t size;
+	struct bmc_mbox_msg *msg;
+	struct mbox_flash_data *mbox_flash;
+
+	mbox_flash = container_of(bl, struct mbox_flash_data, bl);
+
+	prlog(PR_TRACE, "Flash erase at 0x%08x for 0x%08x\n", (u32) pos, (u32) len);
+	while (len > 0) {
+		int rc;
+
+		/* Move window and get a new size to erase */
+		rc = mbox_window_move(mbox_flash, &mbox_flash->write,
+				      MBOX_C_CREATE_WRITE_WINDOW, pos, len, &size);
+		if (rc)
+			return rc;
+
+		msg = msg_alloc(mbox_flash, MBOX_C_MARK_WRITE_ERASED);
+		if (!msg)
+			return FLASH_ERR_MALLOC_FAILED;
+
+		msg_put_u16(msg, 0, pos >> mbox_flash->shift);
+		msg_put_u16(msg, 2, len >> mbox_flash->shift);
+		rc = msg_send(mbox_flash, msg);
+		if (rc) {
+			prlog(PR_ERR, "Failed to enqueue/send BMC MBOX message\n");
+			msg_free_memory(msg);
+			return rc;
+		}
+
+		rc = wait_for_bmc(mbox_flash, MBOX_DEFAULT_TIMEOUT);
+		if (rc) {
+			prlog(PR_ERR, "Error waiting for BMC\n");
+			msg_free_memory(msg);
+			return rc;
+		}
+
+		msg_free_memory(msg);
+
+		/*
+		 * Flush directly, don't mark that region dirty otherwise it
+		 * isn't clear if a write happened there or not
+		 */
+
+		rc = mbox_flash_flush(mbox_flash);
+		if (rc)
+			return rc;
+
+		len -= size;
+		pos += size;
+	}
+
+	return 0;
+}
+
+static int mbox_flash_erase_v1(struct blocklevel_device *bl __unused,
 		uint64_t pos __unused, uint64_t len __unused)
 {
        /*
@@ -859,7 +916,7 @@ static int protocol_init(struct mbox_flash_data *mbox_flash)
 	/* Assume V2 */
 	mbox_flash->bl.read = &mbox_flash_read;
 	mbox_flash->bl.write = &mbox_flash_write;
-	mbox_flash->bl.erase = &mbox_flash_erase;
+	mbox_flash->bl.erase = &mbox_flash_erase_v2;
 	mbox_flash->bl.get_info = &mbox_flash_get_info;
 
 	/* Assume V2 */
@@ -913,6 +970,7 @@ static int protocol_init(struct mbox_flash_data *mbox_flash)
 
 	prlog(PR_INFO, "Detected mbox protocol version %d\n", mbox_flash->version);
 	if (mbox_flash->version == 1) {
+		mbox_flash->bl.erase = &mbox_flash_erase_v1;
 		/* Not all handlers differ, update those which do */
 		mbox_flash->handlers[MBOX_C_GET_MBOX_INFO] = &mbox_flash_do_get_mbox_info;
 		mbox_flash->handlers[MBOX_C_GET_FLASH_INFO] = &mbox_flash_do_get_flash_info_v1;
@@ -956,7 +1014,7 @@ int mbox_flash_init(struct blocklevel_device **bl)
 	/* Assume V2 */
 	mbox_flash->bl.read = &mbox_flash_read;
 	mbox_flash->bl.write = &mbox_flash_write;
-	mbox_flash->bl.erase = &mbox_flash_erase;
+	mbox_flash->bl.erase = &mbox_flash_erase_v2;
 	mbox_flash->bl.get_info = &mbox_flash_get_info;
 
 	if (bmc_mbox_get_attn_reg() & MBOX_ATTN_BMC_REBOOT)
-- 
2.12.2