[PATCH] firmware: arm_ffa: Fix handling of fragmented memory descriptors

[Marc Bonnici]

Fix the handling of MEM_FRAG_TX/RX SMCs when the full memory descriptor
does not fit in a single innovation of a memory sharing request.

The current implementation expects a FFA_MEM_SHARE/FFA_MEM_LEND
call to always receive a FFA_SUCCESS response, however in the
case where a full descriptor does not fit inside the partitions
TX buffer, the call can instead complete with a FFA_MEM_FRAG_RX SMC
to request the next part of the descriptor to be transmitted.

Similarly a FFA_MEM_FRAG_TX call currently only expects
FFA_MEM_FRAG_RX as a response, however once the full descriptor
has been transmitted the FFA_SUCCESS ABI will be used to indicate
successful transmission.

This patch updates the existing code to match the expected
behaviour.

Signed-off-by: Marc Bonnici <marc.bonnici at arm.com>
---
 drivers/firmware/arm_ffa/driver.c | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index 6e0c883ab708..c7d4e3dc7048 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -399,11 +399,17 @@ static int ffa_mem_first_frag(u32 func_id, phys_addr_t buf, u32 buf_sz,
 	if (ret.a0 == FFA_ERROR)
 		return ffa_to_linux_errno((int)ret.a2);
 
-	if (ret.a0 != FFA_SUCCESS)
+	if (ret.a0 == FFA_SUCCESS) {
+		if (handle)
+			*handle = PACK_HANDLE(ret.a2, ret.a3);
+	}
+	else if (ret.a0 == FFA_MEM_FRAG_RX) {
+		if (handle)
+			*handle = PACK_HANDLE(ret.a1, ret.a2);
+	}
+	else {
 		return -EOPNOTSUPP;
-
-	if (handle)
-		*handle = PACK_HANDLE(ret.a2, ret.a3);
+	}
 
 	return frag_len;
 }
@@ -427,10 +433,13 @@ static int ffa_mem_next_frag(u64 handle, u32 frag_len)
 	if (ret.a0 == FFA_ERROR)
 		return ffa_to_linux_errno((int)ret.a2);
 
-	if (ret.a0 != FFA_MEM_FRAG_RX)
-		return -EOPNOTSUPP;
+	if (ret.a0 == FFA_MEM_FRAG_RX) {
+		return ret.a3;
+	} else if (ret.a0 == FFA_SUCCESS) {
+		return 0;
+	}
 
-	return ret.a3;
+	return -EOPNOTSUPP;
 }
 
 static int
-- 
2.25.1