[U-Boot] [PATCH v2 2/3] sunxi: retrieve FEL-provided values to environment variables

[Bernhard Nortmann]

This patch extends the misc_init_r() function on sunxi boards
to test for the presence of a suitable "sunxi" SPL header. If
found, and the loader ("fel" utility) provided a non-zero value
for the boot.scr address, then the corresponding environment
variable fel_scriptaddr gets set.

misc_init_r() also sets (or clears) the "fel_booted" variable depending
on the active boot device, using the same logic as spl_boot_device().

The goal is to provide sufficient information (within the U-Boot
environment) to make intelligent decisions on how to continue the boot
process, allowing specific customizations for the "FEL boot" case.

Signed-off-by: Bernhard Nortmann <bernhard.nortmann at web.de>
---

Changes in v2:
- renamed fel_data_addr to fel_script_addr, discarded fel_data_size
- make sure that FEL-related environment vars are always cleared first
- support minimum and maximum SPL (header) version, more verbose error messages

 board/sunxi/board.c | 56 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 56 insertions(+)

diff --git a/board/sunxi/board.c b/board/sunxi/board.c
index 9c855f6..aa26e57 100644
--- a/board/sunxi/board.c
+++ b/board/sunxi/board.c
@@ -516,6 +516,52 @@ void get_board_serial(struct tag_serialnr *serialnr)
 }
 #endif
 
+#if !defined(CONFIG_SPL_BUILD)
+static int check_signature(unsigned long io_addr, const char *signature,
+			   int length)
+{
+	do {
+		if (readb(io_addr) != *signature)
+			return 0;
+		io_addr++;
+		signature++;
+	} while (--length > 0);
+	return 1;
+}
+
+#define SPL_SIGNATURE			"SPL" /* marks "sunxi" header */
+#define SPL_MIN_VERSION			1
+#define SPL_MAX_VERSION			1
+
+/*
+ * Check the SPL header for the "sunxi" variant. If found: parse values
+ * that might have been passed by the loader ("fel" utility), and update
+ * the environment accordingly.
+ */
+static void parse_spl_header(void)
+{
+	uint8_t spl_header_version;
+	uint32_t fel_script_addr;
+
+	if (check_signature(0x14, SPL_SIGNATURE, 3)) {
+		spl_header_version = readb(0x17);
+		if (spl_header_version < SPL_MIN_VERSION) {
+			printf("sunxi SPL version mismatch: found 0x%02X < required minimum 0x%02X\n",
+			       spl_header_version, SPL_MIN_VERSION);
+			return;
+		}
+		if (spl_header_version > SPL_MAX_VERSION) {
+			printf("sunxi SPL version mismatch: found 0x%02X > maximum supported 0x%02X\n",
+			       spl_header_version, SPL_MAX_VERSION);
+			return;
+		}
+		fel_script_addr = readl(0x18);
+		if (fel_script_addr)
+			setenv_hex("fel_scriptaddr", fel_script_addr);
+	}
+}
+#endif /* !defined(CONFIG_SPL_BUILD) */
+
 #ifdef CONFIG_MISC_INIT_R
 int misc_init_r(void)
 {
@@ -524,6 +570,16 @@ int misc_init_r(void)
 	uint8_t mac_addr[6];
 	int ret;
 
+#if !defined(CONFIG_SPL_BUILD)
+	setenv("fel_booted", NULL);
+	setenv("fel_scriptaddr", NULL);
+	/* determine if we are running in FEL mode */
+	if (readl(4) != 0x4E4F4765 || readl(8) != 0x3054422E) { /* eGON.BT0 */
+		setenv("fel_booted", "1");
+		parse_spl_header();
+	}
+#endif
+
 	ret = sunxi_get_sid(sid);
 	if (ret == 0 && sid[0] != 0 && sid[3] != 0) {
 		if (!getenv("ethaddr")) {
-- 
2.4.6