fpga: zynqmp: support loading encrypted bitfiles

Add supporting new compatible string "u-boot,zynqmp-fpga-enc" to
handle loading encrypted bitfiles.

This feature requires encrypted FSBL, as according to UG1085:
"The CSU automatically locks out the AES key, stored in either BBRAM
 or eFUSEs, as a key source to the AES engine if the FSBL is not
 encrypted. This prevents using the BBRAM or eFUSE as the key source
 to the AES engine during run-time applications."

Signed-off-by: Adrian Fiergolski <adrian.fiergolski@fastree3d.com>
Co-developed-by: Oleksandr Suvorov <oleksandr.suvorov@foundries.io>
Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@foundries.io>
Tested-by: Adrian Fiergolski <adrian.fiergolski@fastree3d.com>
Link: https://lore.kernel.org/r/20220722141614.297383-14-oleksandr.suvorov@foundries.io
Signed-off-by: Michal Simek <michal.simek@amd.com>
diff --git a/drivers/fpga/zynqmppl.c b/drivers/fpga/zynqmppl.c
index fc55d7a..d1491da 100644
--- a/drivers/fpga/zynqmppl.c
+++ b/drivers/fpga/zynqmppl.c
@@ -257,6 +257,11 @@
 		info.authflag = ZYNQMP_FPGA_AUTH_DDR;
 		info.encflag = FPGA_NO_ENC_OR_NO_AUTH;
 		return desc->operations->loads(desc, buf, bsize, &info);
+	case FPGA_XILINX_ZYNQMP_ENC:
+		/* Encryption using device key */
+		info.authflag = FPGA_NO_ENC_OR_NO_AUTH;
+		info.encflag = FPGA_ENC_DEV_KEY;
+		return desc->operations->loads(desc, buf, bsize, &info);
 #endif
 	default:
 		printf("Unsupported bitstream type %d\n", flags);
@@ -360,6 +365,9 @@
 #if CONFIG_IS_ENABLED(FPGA_LOAD_SECURE)
 	if (!strncmp(str, "u-boot,zynqmp-fpga-ddrauth", 26))
 		return FPGA_XILINX_ZYNQMP_DDRAUTH;
+
+	if (!strncmp(str, "u-boot,zynqmp-fpga-enc", 22))
+		return FPGA_XILINX_ZYNQMP_ENC;
 #endif
 	return 0;
 }