fpga: zynq: Add support for encrypted bitstreams

Add support for encrypted bitstreams. For this to work the system
must be booted in secure mode.

In order for on-the-fly decryption to work, the PCAP clock rate
needs to be lowered via the PCAP_RATE_EN bit.

Signed-off-by: Moritz Fischer <mdf@kernel.org>
Acked-by: Michal Simek <michal.simek@xilinx.com>
Signed-off-by: Alan Tull <atull@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

1 files changed, 25 insertions, 3 deletions

diff --git a/drivers/fpga/zynq-fpga.c b/drivers/fpga/zynq-fpga.c
index 34cb98139442..70b15b303471 100644
--- a/drivers/fpga/zynq-fpga.c
+++ b/drivers/fpga/zynq-fpga.c
@@ -72,6 +72,10 @@
 #define CTRL_PCAP_PR_MASK               BIT(27)
 /* Enable PCAP */
 #define CTRL_PCAP_MODE_MASK             BIT(26)
+/* Lower rate to allow decrypt on the fly */
+#define CTRL_PCAP_RATE_EN_MASK          BIT(25)
+/* System booted in secure mode */
+#define CTRL_SEC_EN_MASK                BIT(7)
 
 /* Miscellaneous Control Register bit definitions */
 /* Internal PCAP loopback */
@@ -266,6 +270,17 @@ static int zynq_fpga_ops_write_init(struct fpga_manager *mgr,
         if (err)
                 return err;
 
+        /* check if bitstream is encrypted & and system's still secure */
+        if (info->flags & FPGA_MGR_ENCRYPTED_BITSTREAM) {
+                ctrl = zynq_fpga_read(priv, CTRL_OFFSET);
+                if (!(ctrl & CTRL_SEC_EN_MASK)) {
+                        dev_err(&mgr->dev,
+                                "System not secure, can't use crypted bitstreams\n");
+                        err = -EINVAL;
+                        goto out_err;
+                }
+        }
+
         /* don't globally reset PL if we're doing partial reconfig */
         if (!(info->flags & FPGA_MGR_PARTIAL_RECONFIG)) {
                 if (!zynq_fpga_has_sync(buf, count)) {
@@ -337,12 +352,19 @@ static int zynq_fpga_ops_write_init(struct fpga_manager *mgr,
 
         /* set configuration register with following options:
          * - enable PCAP interface
-         * - set throughput for maximum speed
+         * - set throughput for maximum speed (if bistream not crypted)
          * - set CPU in user mode
          */
         ctrl = zynq_fpga_read(priv, CTRL_OFFSET);
-        zynq_fpga_write(priv, CTRL_OFFSET,
-                        (CTRL_PCAP_PR_MASK | CTRL_PCAP_MODE_MASK | ctrl));
+        if (info->flags & FPGA_MGR_ENCRYPTED_BITSTREAM)
+                zynq_fpga_write(priv, CTRL_OFFSET,
+                                (CTRL_PCAP_PR_MASK | CTRL_PCAP_MODE_MASK
+                                 | CTRL_PCAP_RATE_EN_MASK | ctrl));
+        else
+                zynq_fpga_write(priv, CTRL_OFFSET,
+                                (CTRL_PCAP_PR_MASK | CTRL_PCAP_MODE_MASK
+                                 | ctrl));
+
 
         /* We expect that the command queue is empty right now. */
         status = zynq_fpga_read(priv, STATUS_OFFSET);