qemu: common: Add support for dynamic mtdparts for the platform

Add support for setting the default values for mtd partitions on the
platform. This would be used for updating the firmware image using
uefi capsule update with the dfu mtd backend driver.

Currently, values have been defined for the qemu arm64 platform, with
default values defined for the mtd partitions based on the NOR
flash. This can be subsequently extended for other qemu architectures
which need mtdparts set.

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

board/emulation/common/Kconfig

@@ -0,0 +1,15 @@
+config MTDPARTS_NOR0
+	string "mtd boot partition for nor0"
+	default "64m(u-boot)" if TARGET_QEMU_ARM_64BIT && !TFABOOT
+	depends on SYS_MTDPARTS_RUNTIME
+	help
+	  This define the partition of nor0 used to build mtparts dynamically
+	  for boot from nor0.
+
+config MTDPARTS_NOR1
+	string "mtd u-boot env partition for nor1"
+	default "64m(u-boot-env)" if TARGET_QEMU_ARM_64BIT && !TFABOOT
+	depends on SYS_MTDPARTS_RUNTIME
+	help
+	  This define the partition of nor1 used to build mtparts dynamically
+	  for the u-boot env stored on nor1.

board/emulation/common/Makefile

@@ -0,0 +1,3 @@
+# SPDX-License-Identifier: GPL-2.0+
+
+obj-$(CONFIG_SYS_MTDPARTS_RUNTIME) += qemu_mtdparts.o

board/emulation/common/qemu_mtdparts.c

@@ -0,0 +1,82 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (c) 2020 Linaro Limited
+ */
+
+#include <common.h>
+#include <dm.h>
+#include <mtd.h>
+
+#include <linux/string.h>
+
+#define MTDPARTS_LEN		256
+#define MTDIDS_LEN		128
+
+static void board_get_mtdparts(const char *dev, const char *partition,
+			       char *mtdids, char *mtdparts)
+{
+	/* mtdids: "<dev>=<dev>, ...." */
+	if (mtdids[0] != '\0')
+		strcat(mtdids, ",");
+	strcat(mtdids, dev);
+	strcat(mtdids, "=");
+	strcat(mtdids, dev);
+
+	/* mtdparts: "mtdparts=<dev>:<mtdparts_<dev>>;..." */
+	if (mtdparts[0] != '\0')
+		strncat(mtdparts, ";", MTDPARTS_LEN);
+	else
+		strcat(mtdparts, "mtdparts=");
+
+	strncat(mtdparts, dev, MTDPARTS_LEN);
+	strncat(mtdparts, ":", MTDPARTS_LEN);
+	strncat(mtdparts, partition, MTDPARTS_LEN);
+}
+
+void board_mtdparts_default(const char **mtdids, const char **mtdparts)
+{
+	struct mtd_info *mtd;
+	struct udevice *dev;
+	const char *mtd_partition;
+	static char parts[3 * MTDPARTS_LEN + 1];
+	static char ids[MTDIDS_LEN + 1];
+	static bool mtd_initialized;
+
+	if (mtd_initialized) {
+		*mtdids = ids;
+		*mtdparts = parts;
+		return;
+	}
+
+	memset(parts, 0, sizeof(parts));
+	memset(ids, 0, sizeof(ids));
+
+	/* Currently mtdparts 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 */
+		for (uclass_first_device(UCLASS_MTD, &dev); dev;
+		     uclass_next_device(&dev)) {
+			debug("mtd device = %s\n", dev->name);
+		}
+
+		mtd = get_mtd_device_nm("nor0");
+		if (!IS_ERR_OR_NULL(mtd)) {
+			mtd_partition = CONFIG_MTDPARTS_NOR0;
+			board_get_mtdparts("nor0", mtd_partition, ids, parts);
+			put_mtd_device(mtd);
+		}
+
+		mtd = get_mtd_device_nm("nor1");
+		if (!IS_ERR_OR_NULL(mtd)) {
+			mtd_partition = CONFIG_MTDPARTS_NOR1;
+			board_get_mtdparts("nor1", mtd_partition, ids, parts);
+			put_mtd_device(mtd);
+		}
+	}
+
+	mtd_initialized = true;
+	*mtdids = ids;
+	*mtdparts = parts;
+	debug("%s:mtdids=%s & mtdparts=%s\n", __func__, ids, parts);
+}

board/emulation/qemu-arm/Kconfig

@@ -11,3 +11,10 @@ config BOARD_SPECIFIC_OPTIONS # dummy
 	imply VIRTIO_BLK
 
 endif
+
+if TARGET_QEMU_ARM_64BIT && !TFABOOT
+config BOARD_SPECIFIC_OPTIONS
+	imply SYS_MTDPARTS_RUNTIME
+
+source "board/emulation/common/Kconfig"
+endif