habanalabs: add command buffer module
This patch adds the command buffer (CB) module, which allows the user to
create and destroy CBs and to map them to the user's process
address-space.
A command buffer is a memory blocks that reside in DMA-able address-space
and is physically contiguous so it can be accessed by the device without
MMU translation. The command buffer memory is allocated using the
coherent DMA API.
When creating a new CB, the IOCTL returns a handle of it, and the
user-space process needs to use that handle to mmap the buffer to get a VA
in the user's address-space.
Before destroying (freeing) a CB, the user must unmap the CB's VA using the
CB handle.
Each CB has a reference counter, which tracks its usage in command
submissions and also its mmaps (only a single mmap is allowed).
The driver maintains a pool of pre-allocated CBs in order to reduce
latency during command submissions. In case the pool is empty, the driver
will go to the slow-path of allocating a new CB, i.e. calling
dma_alloc_coherent.
Reviewed-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Oded Gabbay <oded.gabbay@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
diff --git a/include/uapi/misc/habanalabs.h b/include/uapi/misc/habanalabs.h
index a0ec23a..a8edfd3 100644
--- a/include/uapi/misc/habanalabs.h
+++ b/include/uapi/misc/habanalabs.h
@@ -17,4 +17,50 @@
*/
#define GOYA_KMD_SRAM_RESERVED_SIZE_FROM_START 0x8000 /* 32KB */
+/* Opcode to create a new command buffer */
+#define HL_CB_OP_CREATE 0
+/* Opcode to destroy previously created command buffer */
+#define HL_CB_OP_DESTROY 1
+
+struct hl_cb_in {
+ /* Handle of CB or 0 if we want to create one */
+ __u64 cb_handle;
+ /* HL_CB_OP_* */
+ __u32 op;
+ /* Size of CB. Minimum requested size must be PAGE_SIZE */
+ __u32 cb_size;
+ /* Context ID - Currently not in use */
+ __u32 ctx_id;
+ __u32 pad;
+};
+
+struct hl_cb_out {
+ /* Handle of CB */
+ __u64 cb_handle;
+};
+
+union hl_cb_args {
+ struct hl_cb_in in;
+ struct hl_cb_out out;
+};
+
+/*
+ * Command Buffer
+ * - Request a Command Buffer
+ * - Destroy a Command Buffer
+ *
+ * The command buffers are memory blocks that reside in DMA-able address
+ * space and are physically contiguous so they can be accessed by the device
+ * directly. They are allocated using the coherent DMA API.
+ *
+ * When creating a new CB, the IOCTL returns a handle of it, and the user-space
+ * process needs to use that handle to mmap the buffer so it can access them.
+ *
+ */
+#define HL_IOCTL_CB \
+ _IOWR('H', 0x02, union hl_cb_args)
+
+#define HL_COMMAND_START 0x02
+#define HL_COMMAND_END 0x03
+
#endif /* HABANALABS_H_ */