[PATCH 6/6] net: fm: Add support for FIT firmware

[Sean Anderson <sean.anderson@seco.com>]

Fman microcode is executable code (AFAICT) loaded into a
coprocessor. As such, if verified boot is enabled, it must be verified
like other executable code. However, this is not currently done.

This commit adds verified boot functionality by encapsulating the
microcode in a FIT, which can then be signed/verified as normal. By
default we allow fallback to unencapsulated firmware, but if
CONFIG_FIT_SIGNATURE is enabled, then we make it mandatory. Because
existing Layerscape do not use this config (instead enabling
CONFIG_CHAIN_OF_TRUST), this should not break any existing boards.

An example (mildly-abbreviated) its is provided below:

/ {
    #address-cells = <1>;

    images {
        firmware {
            data = /incbin/(/path/to/firmware);
            type = "firmware";
            arch = "arm64";
            compression = "none";
	    signature {
                algo = "sha256,rsa2048";
                key-name-hint = "your key name";
            };
        };
    };

    configurations {
        default = "conf";
        conf {
            description = "Load FMAN microcode";
            fman = "firmware";
        };
    };
};

Signed-off-by: Sean Anderson <sean.anderson@seco.com>
---

 drivers/net/fm/fm.c | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/drivers/net/fm/fm.c b/drivers/net/fm/fm.c
index 39b939cb97..09e13506bf 100644
--- a/drivers/net/fm/fm.c
+++ b/drivers/net/fm/fm.c
@@ -6,6 +6,7 @@
 #include <common.h>
 #include <env.h>
 #include <fs_loader.h>
+#include <image.h>
 #include <malloc.h>
 #include <asm/io.h>
 #include <dm/device_compat.h>
@@ -537,6 +538,23 @@ int fm_init_common(int index, struct ccsr_fman *reg, const char *firmware_name)
 	void *addr = NULL;
 #endif
 
+	rc = fit_check_format(addr, CONFIG_SYS_QE_FMAN_FW_LENGTH);
+	if (!rc) {
+		size_t unused;
+		const void *new_addr;
+
+		rc = fit_get_data_conf_prop(addr, "fman", &new_addr, &unused);
+		if (rc)
+			return rc;
+		addr = (void *)new_addr;
+	} else if (CONFIG_IS_ENABLED(FIT_SIGNATURE)) {
+		/*
+		 * Using a (signed) FIT wrapper is mandatory if we are
+		 * doing verified boot.
+		 */
+		return rc;
+	}
+
 	/* Upload the Fman microcode if it's present */
 	rc = fman_upload_firmware(index, &reg->fm_imem, addr);
 	if (rc)
-- 
2.25.1