qemu: common: Set dfu_alt_info variable for the platform

The dfu framework uses the dfu_alt_info environment variable to get
information that is needed for performing the firmware update. Add
logic to set the dfu_alt_info for the qemu arm64 platform to reflect
the two mtd partitions created for the u-boot env and the firmware
image. This can be subsequently extended for other qemu architectures
which need this variable set.

Signed-off-by: Sughosh Ganu <sughosh.ganu@linaro.org>

board/emulation/common/Makefile

@@ -1,3 +1,4 @@
 # SPDX-License-Identifier: GPL-2.0+
 
 obj-$(CONFIG_SYS_MTDPARTS_RUNTIME) += qemu_mtdparts.o
+obj-$(CONFIG_SET_DFU_ALT_INFO) += qemu_dfu.o

board/emulation/common/qemu_dfu.c

@@ -0,0 +1,68 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2020 Linaro Limited
+ */
+
+#include <common.h>
+#include <dfu.h>
+#include <env.h>
+#include <memalign.h>
+#include <mtd.h>
+
+#define DFU_ALT_BUF_LEN		SZ_1K
+
+static void board_get_alt_info(struct mtd_info *mtd, char *buf)
+{
+	struct mtd_info *part;
+	bool first = true;
+	const char *name;
+	int len, partnum = 0;
+
+	name = mtd->name;
+	len = strlen(buf);
+
+	if (buf[0] != '\0')
+		len += snprintf(buf + len, DFU_ALT_BUF_LEN - len, "&");
+	len += snprintf(buf + len, DFU_ALT_BUF_LEN - len,
+			"mtd %s=", name);
+
+	list_for_each_entry(part, &mtd->partitions, node) {
+		partnum++;
+		if (!first)
+			len += snprintf(buf + len, DFU_ALT_BUF_LEN - len, ";");
+		first = false;
+
+		len += snprintf(buf + len, DFU_ALT_BUF_LEN - len,
+				"%s part %d",
+				part->name, partnum);
+	}
+}
+
+void set_dfu_alt_info(char *interface, char *devstr)
+{
+	struct mtd_info *mtd;
+
+	ALLOC_CACHE_ALIGN_BUFFER(char, buf, DFU_ALT_BUF_LEN);
+
+	if (env_get("dfu_alt_info"))
+		return;
+
+	memset(buf, 0, sizeof(buf));
+
+	/*
+	 * Currently dfu_alt_info is needed on Qemu ARM64 for
+	 * capsule updates
+	*/
+	if (IS_ENABLED(CONFIG_EFI_CAPSULE_FIRMWARE_MANAGEMENT) &&
+	    IS_ENABLED(CONFIG_TARGET_QEMU_ARM_64BIT)) {
+		/* probe all MTD devices */
+		mtd_probe_devices();
+
+		mtd = get_mtd_device_nm("nor0");
+		if (!IS_ERR_OR_NULL(mtd))
+			board_get_alt_info(mtd, buf);
+	}
+
+	env_set("dfu_alt_info", buf);
+	printf("dfu_alt_info set\n");
+}

board/emulation/qemu-arm/Kconfig

@@ -15,6 +15,7 @@ endif
 if TARGET_QEMU_ARM_64BIT && !TFABOOT
 config BOARD_SPECIFIC_OPTIONS
 	imply SYS_MTDPARTS_RUNTIME
+	imply SET_DFU_ALT_INFO
 
 source "board/emulation/common/Kconfig"
 endif