boot: android: import addBootConfigParameters() from AOSP

To properly implement Android boot image v4, U-Boot must be able to
add additional entries to the bootconfig.

Add `add_bootconfig_parameters()` to do so.

This has been imported from Google's U-Boot source[1]
The variables/function names have been reworked to be
compliant with U-Boot's coding style.

[1] https://android.googlesource.com/platform/external/u-boot/+/7af0a0506d4de6f5ea147d10fb0664a8af07d326

Signed-off-by: Mattijs Korpershoek (TI.com) <[email protected]>
Reviewed-by: Mattijs Korpershoek <[email protected]>
Signed-off-by: Guillaume La Roque (TI.com) <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Mattijs Korpershoek <[email protected]>

1 files changed, 40 insertions, 0 deletions

diff --git a/boot/image-android.c b/boot/image-android.c
index ea47869a64c..5407390ef36 100644
--- a/boot/image-android.c
+++ b/boot/image-android.c
@@ -57,6 +57,46 @@ static ulong add_trailer(ulong bootconfig_start_addr, ulong bootconfig_size)
 	return BOOTCONFIG_TRAILER_SIZE;
 }
 
+/*
+ * Add a string of boot config parameters to memory appended by the trailer.
+ * NOTE: This function expects bootconfig_start_addr to be already mapped.
+ *       It works directly with the mapped pointer, not a physical address.
+ */
+static long add_bootconfig_parameters(char *params, long params_len,
+				      ulong bootconfig_start_addr, u32 bootconfig_size)
+{
+	long applied_bytes = 0;
+	long new_size = 0;
+	ulong end;
+
+	if (!params || !bootconfig_start_addr)
+		return -EINVAL;
+
+	if (params_len == 0)
+		return 0;
+
+	end = bootconfig_start_addr + bootconfig_size;
+
+	if (is_trailer_present(end)) {
+		end -= BOOTCONFIG_TRAILER_SIZE;
+		applied_bytes -= BOOTCONFIG_TRAILER_SIZE;
+		memcpy(&new_size, (void *)end, BOOTCONFIG_SIZE_SIZE);
+	} else {
+		/*
+		 * When no trailer is present, the bootconfig_size includes the actual content.
+		 * We should write new parameters right after the existing content.
+		 */
+		end = bootconfig_start_addr + bootconfig_size;
+		new_size = bootconfig_size;
+	}
+
+	memcpy((void *)end, params, params_len);
+	applied_bytes += params_len;
+	applied_bytes += add_trailer(bootconfig_start_addr,
+				     bootconfig_size + applied_bytes);
+	return applied_bytes;
+}
+
 __weak ulong get_avendor_bootimg_addr(void)
 {
 	return -1;