[RFC v2 3/4] drivers: fpga: Add user-key encrypted FPGA Image loading support

[Nava kishore Manne <nava.manne@xilinx.com>]

This patch adds user-key encrypted FPGA Image loading support
to the framework.

Signed-off-by: Nava kishore Manne <nava.manne@xilinx.com>
---
Changes for v2:
                -Both DT properties ie; encrypted-key-name and encrypted-user-key-fpga-config
                 are targeted to use for the same use cases but ideally encrypted-key-name
                 is enough to serve the purpose so updated the code to remove the unwanted
                 encrypted-user-key-fpga-config property dependency as suggested by Rob

 drivers/fpga/fpga-mgr.c       | 15 +++++++++++++++
 drivers/fpga/of-fpga-region.c | 11 +++++++++++
 include/linux/fpga/fpga-mgr.h |  7 +++++++
 3 files changed, 33 insertions(+)

diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
index b85bc47c91a9..3e79ab8cc86f 100644
--- a/drivers/fpga/fpga-mgr.c
+++ b/drivers/fpga/fpga-mgr.c
@@ -325,6 +325,7 @@ static int fpga_mgr_firmware_load(struct fpga_manager *mgr,
 				  const char *image_name)
 {
 	struct device *dev = &mgr->dev;
+	const struct firmware *enc_fw;
 	const struct firmware *fw;
 	int ret;
 
@@ -339,8 +340,22 @@ static int fpga_mgr_firmware_load(struct fpga_manager *mgr,
 		return ret;
 	}
 
+	if (info->encrypted_key_name) {
+		ret = request_firmware(&enc_fw, info->encrypted_key_name, dev);
+		if (ret) {
+			mgr->state = FPGA_MGR_STATE_FIRMWARE_REQ_ERR;
+			dev_err(dev, "Error requesting firmware %s\n",
+				info->encrypted_key_name);
+			return ret;
+		}
+		info->enc_key_buf = enc_fw->data;
+		info->enc_key_buf_size = enc_fw->size;
+	}
+
 	ret = fpga_mgr_buf_load(mgr, info, fw->data, fw->size);
 
+	if (info->encrypted_key_name)
+		release_firmware(enc_fw);
 	release_firmware(fw);
 
 	return ret;
diff --git a/drivers/fpga/of-fpga-region.c b/drivers/fpga/of-fpga-region.c
index e405309baadc..88d8c9049a2f 100644
--- a/drivers/fpga/of-fpga-region.c
+++ b/drivers/fpga/of-fpga-region.c
@@ -195,6 +195,7 @@ static struct fpga_image_info *of_fpga_region_parse_ov(
 {
 	struct device *dev = &region->dev;
 	struct fpga_image_info *info;
+	const char *encrypted_key_name;
 	const char *firmware_name;
 	int ret;
 
@@ -228,6 +229,16 @@ static struct fpga_image_info *of_fpga_region_parse_ov(
 	if (of_property_read_bool(overlay, "encrypted-fpga-config"))
 		info->flags |= FPGA_MGR_ENCRYPTED_BITSTREAM;
 
+	if (!of_property_read_string(overlay, "encrypted-key-name",
+				     &encrypted_key_name)) {
+		info->encrypted_key_name =
+			devm_kstrdup(dev, encrypted_key_name, GFP_KERNEL);
+		if (!info->encrypted_key_name)
+			return ERR_PTR(-ENOMEM);
+
+		info->flags |= FPGA_MGR_ENCRYPTED_USER_KEY_BITSTREAM;
+	}
+
 	if (!of_property_read_string(overlay, "firmware-name",
 				     &firmware_name)) {
 		info->firmware_name = devm_kstrdup(dev, firmware_name,
diff --git a/include/linux/fpga/fpga-mgr.h b/include/linux/fpga/fpga-mgr.h
index 3a32b8e20185..ff14bc51bdd3 100644
--- a/include/linux/fpga/fpga-mgr.h
+++ b/include/linux/fpga/fpga-mgr.h
@@ -67,12 +67,15 @@ enum fpga_mgr_states {
  * %FPGA_MGR_BITSTREAM_LSB_FIRST: SPI bitstream bit order is LSB first
  *
  * %FPGA_MGR_COMPRESSED_BITSTREAM: FPGA bitstream is compressed
+ * %FPGA_MGR_ENCRYPTED_USER_KEY_BITSTREAM: indicates bitstream is encrypted
+ *					   with user-key
  */
 #define FPGA_MGR_PARTIAL_RECONFIG	BIT(0)
 #define FPGA_MGR_EXTERNAL_CONFIG	BIT(1)
 #define FPGA_MGR_ENCRYPTED_BITSTREAM	BIT(2)
 #define FPGA_MGR_BITSTREAM_LSB_FIRST	BIT(3)
 #define FPGA_MGR_COMPRESSED_BITSTREAM	BIT(4)
+#define FPGA_MGR_ENCRYPTED_USER_KEY_BITSTREAM	BIT(5)
 
 /**
  * struct fpga_image_info - information specific to a FPGA image
@@ -82,6 +85,7 @@ enum fpga_mgr_states {
  * @config_complete_timeout_us: maximum time for FPGA to switch to operating
  *	   status in the write_complete op.
  * @firmware_name: name of FPGA image firmware file
+ * @encrypted_key_name: name of the FPGA image encrypted user-key file
  * @sgt: scatter/gather table containing FPGA image
  * @buf: contiguous buffer containing FPGA image
  * @count: size of buf
@@ -95,8 +99,11 @@ struct fpga_image_info {
 	u32 disable_timeout_us;
 	u32 config_complete_timeout_us;
 	char *firmware_name;
+	char *encrypted_key_name;
 	struct sg_table *sgt;
+	const char *enc_key_buf;
 	const char *buf;
+	size_t enc_key_buf_size;
 	size_t count;
 	int region_id;
 	struct device *dev;
-- 
2.17.1