[PATCH v4 16/17] firmware: arm_ffa: Update memory descriptor to support v1.1 format

[Sudeep Holla]

Update memory transaction descriptor structure to accommodate couple of
new entries in v1.1 which were previously marked reserved and MBZ(must
be zero).

It also removes the flexible array member ep_mem_access in the memory
transaction descriptor structure as it need not be at fixed offset.
Also update ffa_mem_desc_offset() accessor to handle both old and new
formats of memory transaction descriptors.

The updated ffa_mem_region structure aligns with new format in v1.1 and
hence the driver/user must take care not to use members beyond and
including ep_mem_offset when using the old format.

Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
---
 drivers/firmware/arm_ffa/driver.c | 11 ++++++++---
 include/linux/arm_ffa.h           | 32 +++++++++++++++++++++-----------
 2 files changed, 29 insertions(+), 14 deletions(-)

diff --git a/drivers/firmware/arm_ffa/driver.c b/drivers/firmware/arm_ffa/driver.c
index 4de08ffce599..7b3db675454c 100644
--- a/drivers/firmware/arm_ffa/driver.c
+++ b/drivers/firmware/arm_ffa/driver.c
@@ -423,7 +423,7 @@ static u32 ffa_get_num_pages_sg(struct scatterlist *sg)
 	return num_pages;
 }
 
-static u8 ffa_memory_attributes_get(u32 func_id)
+static u16 ffa_memory_attributes_get(u32 func_id)
 {
 	/*
 	 * For the memory lend or donate operation, if the receiver is a PE or
@@ -467,9 +467,14 @@ ffa_setup_and_transmit(u32 func_id, void *buffer, u32 max_fragsize,
 		ep_mem_access->reserved = 0;
 	}
 	mem_region->handle = 0;
-	mem_region->reserved_0 = 0;
-	mem_region->reserved_1 = 0;
 	mem_region->ep_count = args->nattrs;
+	if (drv_info->version <= FFA_VERSION_1_0) {
+		mem_region->ep_mem_size = 0;
+	} else {
+		mem_region->ep_mem_size = sizeof(*ep_mem_access);
+		mem_region->ep_mem_offset = sizeof(*mem_region);
+		memset(mem_region->reserved, 0, 12);
+	}
 
 	composite = buffer + composite_offset;
 	composite->total_pg_cnt = ffa_get_num_pages_sg(args->sg);
diff --git a/include/linux/arm_ffa.h b/include/linux/arm_ffa.h
index 2444d596b703..510fe78bff71 100644
--- a/include/linux/arm_ffa.h
+++ b/include/linux/arm_ffa.h
@@ -298,8 +298,8 @@ struct ffa_mem_region {
 #define FFA_MEM_NON_SHAREABLE	(0)
 #define FFA_MEM_OUTER_SHAREABLE	(2)
 #define FFA_MEM_INNER_SHAREABLE	(3)
-	u8 attributes;
-	u8 reserved_0;
+	/* Memory region attributes, upper byte MBZ pre v1.1 */
+	u16 attributes;
 /*
  * Clear memory region contents after unmapping it from the sender and
  * before mapping it for any receiver.
@@ -337,30 +337,40 @@ struct ffa_mem_region {
 	 * memory region.
 	 */
 	u64 tag;
-	u32 reserved_1;
+	/* Size of each endpoint memory access descriptor, MBZ pre v1.1 */
+	u32 ep_mem_size;
 	/*
 	 * The number of `ffa_mem_region_attributes` entries included in this
 	 * transaction.
 	 */
 	u32 ep_count;
 	/*
-	 * An array of endpoint memory access descriptors.
-	 * Each one specifies a memory region offset, an endpoint and the
-	 * attributes with which this memory region should be mapped in that
-	 * endpoint's page table.
+	 * 16-byte aligned offset from the base address of this descriptor
+	 * to the first element of the endpoint memory access descriptor array
+	 * Valid only from v1.1
 	 */
-	struct ffa_mem_region_attributes ep_mem_access[];
+	u32 ep_mem_offset;
+	/* MBZ, valid only from v1.1 */
+	u32 reserved[3];
 };
 
-#define	COMPOSITE_OFFSET(x)	\
-	(offsetof(struct ffa_mem_region, ep_mem_access[x]))
 #define CONSTITUENTS_OFFSET(x)	\
 	(offsetof(struct ffa_composite_mem_region, constituents[x]))
 
 static inline u32
 ffa_mem_desc_offset(struct ffa_mem_region *buf, int count, u32 ffa_version)
 {
-	return COMPOSITE_OFFSET(0);
+	u32 offset = count * sizeof(struct ffa_mem_region_attributes);
+	/*
+	 * Earlier to v1.1, the endpoint memory descriptor array started at
+	 * offset 32(i.e. offset of ep_mem_offset in the current structure)
+	 */
+	if (ffa_version <= FFA_VERSION_1_0)
+		offset += offsetof(struct ffa_mem_region, ep_mem_offset);
+	else
+		offset += sizeof(struct ffa_mem_region);
+
+	return offset;
 }
 
 struct ffa_mem_ops_args {

-- 
2.42.0