fastboot: Move fastboot to drivers/fastboot

Separate CMD_FASTBOOT from FASTBOOT and move code and configuration to
drivers/fastboot.

Switch dependencies on FASTBOOT to USB_FUNCTION_FASTBOOT as anyone who wants
FASTBOOT before this series wants USB_FUNCTION_FASTBOOT. Split
USB_FUNCTION_FASTBOOT from FASTBOOT so they retain their existing
behaviour.

Signed-off-by: Alex Kiernan <alex.kiernan@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Acked-by: Joe Hershberger <joe.hershberger@ni.com>

4 files changed, 767 insertions, 0 deletions

diff --git a/drivers/fastboot/Kconfig b/drivers/fastboot/Kconfig
new file mode 100644
index 0000000000..93a8ac64e7
--- /dev/null
+++ b/drivers/fastboot/Kconfig
@@ -0,0 +1,123 @@
+menu "Fastboot support"
+
+config FASTBOOT
+	bool
+	imply ANDROID_BOOT_IMAGE
+	imply CMD_FASTBOOT
+
+config USB_FUNCTION_FASTBOOT
+	bool "Enable USB fastboot gadget"
+	depends on USB_GADGET
+	default y if ARCH_SUNXI && USB_MUSB_GADGET
+	select FASTBOOT
+	select USB_GADGET_DOWNLOAD
+	help
+	  This enables the USB part of the fastboot gadget.
+
+if FASTBOOT
+
+config FASTBOOT_BUF_ADDR
+	hex "Define FASTBOOT buffer address"
+	default 0x82000000 if MX6SX || MX6SL || MX6UL || MX6SLL
+	default 0x81000000 if ARCH_OMAP2PLUS
+	default 0x42000000 if ARCH_SUNXI && !MACH_SUN9I
+	default 0x22000000 if ARCH_SUNXI && MACH_SUN9I
+	default 0x60800800 if ROCKCHIP_RK3036 || ROCKCHIP_RK3188 || \
+				ROCKCHIP_RK322X
+	default 0x800800 if ROCKCHIP_RK3288 || ROCKCHIP_RK3329 || \
+				ROCKCHIP_RK3399
+	default 0x280000 if ROCKCHIP_RK3368
+	default 0x100000 if ARCH_ZYNQMP
+	help
+	  The fastboot protocol requires a large memory buffer for
+	  downloads. Define this to the starting RAM address to use for
+	  downloaded images.
+
+config FASTBOOT_BUF_SIZE
+	hex "Define FASTBOOT buffer size"
+	default 0x8000000 if ARCH_ROCKCHIP
+	default 0x6000000 if ARCH_ZYNQMP
+	default 0x2000000 if ARCH_SUNXI
+	default 0x7000000
+	help
+	  The fastboot protocol requires a large memory buffer for
+	  downloads. This buffer should be as large as possible for a
+	  platform. Define this to the size available RAM for fastboot.
+
+config FASTBOOT_USB_DEV
+	int "USB controller number"
+	depends on USB_FUNCTION_FASTBOOT
+	default 0
+	help
+	  Some boards have USB OTG controller other than 0. Define this
+	  option so it can be used in compiled environment (e.g. in
+	  CONFIG_BOOTCOMMAND).
+
+config FASTBOOT_FLASH
+	bool "Enable FASTBOOT FLASH command"
+	default y if ARCH_SUNXI
+	help
+	  The fastboot protocol includes a "flash" command for writing
+	  the downloaded image to a non-volatile storage device. Define
+	  this to enable the "fastboot flash" command.
+
+choice
+	prompt "Flash provider for FASTBOOT"
+	depends on FASTBOOT_FLASH
+
+config FASTBOOT_FLASH_MMC
+	bool "FASTBOOT on MMC"
+	depends on MMC
+
+config FASTBOOT_FLASH_NAND
+	bool "FASTBOOT on NAND"
+	depends on NAND
+
+endchoice
+
+config FASTBOOT_FLASH_MMC_DEV
+	int "Define FASTBOOT MMC FLASH default device"
+	depends on FASTBOOT_FLASH_MMC
+	default 0 if ARCH_SUNXI && MMC_SUNXI_SLOT_EXTRA = -1
+	default 1 if ARCH_SUNXI && MMC_SUNXI_SLOT_EXTRA != -1
+	help
+	  The fastboot "flash" command requires additional information
+	  regarding the non-volatile storage device. Define this to
+	  the eMMC device that fastboot should use to store the image.
+
+config FASTBOOT_FLASH_NAND_DEV
+	int "Define FASTBOOT NAND FLASH default device"
+	depends on FASTBOOT_FLASH_NAND
+	depends on CMD_MTDPARTS
+	default 0 if ARCH_SUNXI && NAND_SUNXI
+	help
+	  The fastboot "flash" command requires additional information
+	  regarding the non-volatile storage device. Define this to
+	  the NAND device that fastboot should use to store the image.
+
+config FASTBOOT_GPT_NAME
+	string "Target name for updating GPT"
+	depends on FASTBOOT_FLASH
+	default "gpt"
+	help
+	  The fastboot "flash" command supports writing the downloaded
+	  image to the Protective MBR and the Primary GUID Partition
+	  Table. (Additionally, this downloaded image is post-processed
+	  to generate and write the Backup GUID Partition Table.)
+	  This occurs when the specified "partition name" on the
+	  "fastboot flash" command line matches the value defined here.
+	  The default target name for updating GPT is "gpt".
+
+config FASTBOOT_MBR_NAME
+	string "Target name for updating MBR"
+	depends on FASTBOOT_FLASH
+	default "mbr"
+	help
+	  The fastboot "flash" command allows to write the downloaded image
+	  to the Master Boot Record. This occurs when the "partition name"
+	  specified on the "fastboot flash" command line matches the value
+	  defined here. The default target name for updating MBR is "mbr".
+
+endif # FASTBOOT
+
+endmenu
diff --git a/drivers/fastboot/Makefile b/drivers/fastboot/Makefile
new file mode 100644
index 0000000000..651fbf0935
--- /dev/null
+++ b/drivers/fastboot/Makefile
@@ -0,0 +1,8 @@
+# SPDX-License-Identifier:      GPL-2.0+
+
+ifdef CONFIG_FASTBOOT_FLASH_MMC_DEV
+obj-y += fb_mmc.o
+endif
+ifdef CONFIG_FASTBOOT_FLASH_NAND_DEV
+obj-y += fb_nand.o
+endif
diff --git a/drivers/fastboot/fb_mmc.c b/drivers/fastboot/fb_mmc.c
new file mode 100644
index 0000000000..46f0073dbc
--- /dev/null
+++ b/drivers/fastboot/fb_mmc.c
@@ -0,0 +1,406 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2014 Broadcom Corporation.
+ */
+
+#include <config.h>
+#include <common.h>
+#include <blk.h>
+#include <fastboot.h>
+#include <fb_mmc.h>
+#include <image-sparse.h>
+#include <part.h>
+#include <mmc.h>
+#include <div64.h>
+#include <linux/compat.h>
+#include <android_image.h>
+
+/*
+ * FIXME: Ensure we always set these names via Kconfig once xxx_PARTITION is
+ * migrated
+ */
+#ifndef CONFIG_FASTBOOT_GPT_NAME
+#define CONFIG_FASTBOOT_GPT_NAME "gpt"
+#endif
+
+
+#ifndef CONFIG_FASTBOOT_MBR_NAME
+#define CONFIG_FASTBOOT_MBR_NAME "mbr"
+#endif
+
+#define BOOT_PARTITION_NAME "boot"
+
+struct fb_mmc_sparse {
+	struct blk_desc	*dev_desc;
+};
+
+static int part_get_info_by_name_or_alias(struct blk_desc *dev_desc,
+		const char *name, disk_partition_t *info)
+{
+	int ret;
+
+	ret = part_get_info_by_name(dev_desc, name, info);
+	if (ret < 0) {
+		/* strlen("fastboot_partition_alias_") + 32(part_name) + 1 */
+		char env_alias_name[25 + 32 + 1];
+		char *aliased_part_name;
+
+		/* check for alias */
+		strcpy(env_alias_name, "fastboot_partition_alias_");
+		strncat(env_alias_name, name, 32);
+		aliased_part_name = env_get(env_alias_name);
+		if (aliased_part_name != NULL)
+			ret = part_get_info_by_name(dev_desc,
+					aliased_part_name, info);
+	}
+	return ret;
+}
+
+static lbaint_t fb_mmc_sparse_write(struct sparse_storage *info,
+		lbaint_t blk, lbaint_t blkcnt, const void *buffer)
+{
+	struct fb_mmc_sparse *sparse = info->priv;
+	struct blk_desc *dev_desc = sparse->dev_desc;
+
+	return blk_dwrite(dev_desc, blk, blkcnt, buffer);
+}
+
+static lbaint_t fb_mmc_sparse_reserve(struct sparse_storage *info,
+		lbaint_t blk, lbaint_t blkcnt)
+{
+	return blkcnt;
+}
+
+static void write_raw_image(struct blk_desc *dev_desc, disk_partition_t *info,
+		const char *part_name, void *buffer,
+		unsigned int download_bytes)
+{
+	lbaint_t blkcnt;
+	lbaint_t blks;
+
+	/* determine number of blocks to write */
+	blkcnt = ((download_bytes + (info->blksz - 1)) & ~(info->blksz - 1));
+	blkcnt = lldiv(blkcnt, info->blksz);
+
+	if (blkcnt > info->size) {
+		pr_err("too large for partition: '%s'\n", part_name);
+		fastboot_fail("too large for partition");
+		return;
+	}
+
+	puts("Flashing Raw Image\n");
+
+	blks = blk_dwrite(dev_desc, info->start, blkcnt, buffer);
+	if (blks != blkcnt) {
+		pr_err("failed writing to device %d\n", dev_desc->devnum);
+		fastboot_fail("failed writing to device");
+		return;
+	}
+
+	printf("........ wrote " LBAFU " bytes to '%s'\n", blkcnt * info->blksz,
+	       part_name);
+	fastboot_okay("");
+}
+
+#ifdef CONFIG_ANDROID_BOOT_IMAGE
+/**
+ * Read Android boot image header from boot partition.
+ *
+ * @param[in] dev_desc MMC device descriptor
+ * @param[in] info Boot partition info
+ * @param[out] hdr Where to store read boot image header
+ *
+ * @return Boot image header sectors count or 0 on error
+ */
+static lbaint_t fb_mmc_get_boot_header(struct blk_desc *dev_desc,
+				       disk_partition_t *info,
+				       struct andr_img_hdr *hdr)
+{
+	ulong sector_size;		/* boot partition sector size */
+	lbaint_t hdr_sectors;		/* boot image header sectors count */
+	int res;
+
+	/* Calculate boot image sectors count */
+	sector_size = info->blksz;
+	hdr_sectors = DIV_ROUND_UP(sizeof(struct andr_img_hdr), sector_size);
+	if (hdr_sectors == 0) {
+		pr_err("invalid number of boot sectors: 0");
+		fastboot_fail("invalid number of boot sectors: 0");
+		return 0;
+	}
+
+	/* Read the boot image header */
+	res = blk_dread(dev_desc, info->start, hdr_sectors, (void *)hdr);
+	if (res != hdr_sectors) {
+		pr_err("cannot read header from boot partition");
+		fastboot_fail("cannot read header from boot partition");
+		return 0;
+	}
+
+	/* Check boot header magic string */
+	res = android_image_check_header(hdr);
+	if (res != 0) {
+		pr_err("bad boot image magic");
+		fastboot_fail("boot partition not initialized");
+		return 0;
+	}
+
+	return hdr_sectors;
+}
+
+/**
+ * Write downloaded zImage to boot partition and repack it properly.
+ *
+ * @param dev_desc MMC device descriptor
+ * @param download_buffer Address to fastboot buffer with zImage in it
+ * @param download_bytes Size of fastboot buffer, in bytes
+ *
+ * @return 0 on success or -1 on error
+ */
+static int fb_mmc_update_zimage(struct blk_desc *dev_desc,
+				void *download_buffer,
+				unsigned int download_bytes)
+{
+	uintptr_t hdr_addr;			/* boot image header address */
+	struct andr_img_hdr *hdr;		/* boot image header */
+	lbaint_t hdr_sectors;			/* boot image header sectors */
+	u8 *ramdisk_buffer;
+	u32 ramdisk_sector_start;
+	u32 ramdisk_sectors;
+	u32 kernel_sector_start;
+	u32 kernel_sectors;
+	u32 sectors_per_page;
+	disk_partition_t info;
+	int res;
+
+	puts("Flashing zImage\n");
+
+	/* Get boot partition info */
+	res = part_get_info_by_name(dev_desc, BOOT_PARTITION_NAME, &info);
+	if (res < 0) {
+		pr_err("cannot find boot partition");
+		fastboot_fail("cannot find boot partition");
+		return -1;
+	}
+
+	/* Put boot image header in fastboot buffer after downloaded zImage */
+	hdr_addr = (uintptr_t)download_buffer + ALIGN(download_bytes, PAGE_SIZE);
+	hdr = (struct andr_img_hdr *)hdr_addr;
+
+	/* Read boot image header */
+	hdr_sectors = fb_mmc_get_boot_header(dev_desc, &info, hdr);
+	if (hdr_sectors == 0) {
+		pr_err("unable to read boot image header");
+		fastboot_fail("unable to read boot image header");
+		return -1;
+	}
+
+	/* Check if boot image has second stage in it (we don't support it) */
+	if (hdr->second_size > 0) {
+		pr_err("moving second stage is not supported yet");
+		fastboot_fail("moving second stage is not supported yet");
+		return -1;
+	}
+
+	/* Extract ramdisk location */
+	sectors_per_page = hdr->page_size / info.blksz;
+	ramdisk_sector_start = info.start + sectors_per_page;
+	ramdisk_sector_start += DIV_ROUND_UP(hdr->kernel_size, hdr->page_size) *
+					     sectors_per_page;
+	ramdisk_sectors = DIV_ROUND_UP(hdr->ramdisk_size, hdr->page_size) *
+				       sectors_per_page;
+
+	/* Read ramdisk and put it in fastboot buffer after boot image header */
+	ramdisk_buffer = (u8 *)hdr + (hdr_sectors * info.blksz);
+	res = blk_dread(dev_desc, ramdisk_sector_start, ramdisk_sectors,
+			ramdisk_buffer);
+	if (res != ramdisk_sectors) {
+		pr_err("cannot read ramdisk from boot partition");
+		fastboot_fail("cannot read ramdisk from boot partition");
+		return -1;
+	}
+
+	/* Write new kernel size to boot image header */
+	hdr->kernel_size = download_bytes;
+	res = blk_dwrite(dev_desc, info.start, hdr_sectors, (void *)hdr);
+	if (res == 0) {
+		pr_err("cannot writeback boot image header");
+		fastboot_fail("cannot write back boot image header");
+		return -1;
+	}
+
+	/* Write the new downloaded kernel */
+	kernel_sector_start = info.start + sectors_per_page;
+	kernel_sectors = DIV_ROUND_UP(hdr->kernel_size, hdr->page_size) *
+				      sectors_per_page;
+	res = blk_dwrite(dev_desc, kernel_sector_start, kernel_sectors,
+			 download_buffer);
+	if (res == 0) {
+		pr_err("cannot write new kernel");
+		fastboot_fail("cannot write new kernel");
+		return -1;
+	}
+
+	/* Write the saved ramdisk back */
+	ramdisk_sector_start = info.start + sectors_per_page;
+	ramdisk_sector_start += DIV_ROUND_UP(hdr->kernel_size, hdr->page_size) *
+					     sectors_per_page;
+	res = blk_dwrite(dev_desc, ramdisk_sector_start, ramdisk_sectors,
+			 ramdisk_buffer);
+	if (res == 0) {
+		pr_err("cannot write back original ramdisk");
+		fastboot_fail("cannot write back original ramdisk");
+		return -1;
+	}
+
+	puts("........ zImage was updated in boot partition\n");
+	fastboot_okay("");
+	return 0;
+}
+#endif
+
+void fb_mmc_flash_write(const char *cmd, void *download_buffer,
+			unsigned int download_bytes)
+{
+	struct blk_desc *dev_desc;
+	disk_partition_t info;
+
+	dev_desc = blk_get_dev("mmc", CONFIG_FASTBOOT_FLASH_MMC_DEV);
+	if (!dev_desc || dev_desc->type == DEV_TYPE_UNKNOWN) {
+		pr_err("invalid mmc device\n");
+		fastboot_fail("invalid mmc device");
+		return;
+	}
+
+#if CONFIG_IS_ENABLED(EFI_PARTITION)
+	if (strcmp(cmd, CONFIG_FASTBOOT_GPT_NAME) == 0) {
+		printf("%s: updating MBR, Primary and Backup GPT(s)\n",
+		       __func__);
+		if (is_valid_gpt_buf(dev_desc, download_buffer)) {
+			printf("%s: invalid GPT - refusing to write to flash\n",
+			       __func__);
+			fastboot_fail("invalid GPT partition");
+			return;
+		}
+		if (write_mbr_and_gpt_partitions(dev_desc, download_buffer)) {
+			printf("%s: writing GPT partitions failed\n", __func__);
+			fastboot_fail("writing GPT partitions failed");
+			return;
+		}
+		printf("........ success\n");
+		fastboot_okay("");
+		return;
+	}
+#endif
+
+#if CONFIG_IS_ENABLED(DOS_PARTITION)
+	if (strcmp(cmd, CONFIG_FASTBOOT_MBR_NAME) == 0) {
+		printf("%s: updating MBR\n", __func__);
+		if (is_valid_dos_buf(download_buffer)) {
+			printf("%s: invalid MBR - refusing to write to flash\n",
+			       __func__);
+			fastboot_fail("invalid MBR partition");
+			return;
+		}
+		if (write_mbr_partition(dev_desc, download_buffer)) {
+			printf("%s: writing MBR partition failed\n", __func__);
+			fastboot_fail("writing MBR partition failed");
+			return;
+		}
+		printf("........ success\n");
+		fastboot_okay("");
+		return;
+	}
+#endif
+
+#ifdef CONFIG_ANDROID_BOOT_IMAGE
+	if (strncasecmp(cmd, "zimage", 6) == 0) {
+		fb_mmc_update_zimage(dev_desc, download_buffer, download_bytes);
+		return;
+	}
+#endif
+
+	if (part_get_info_by_name_or_alias(dev_desc, cmd, &info) < 0) {
+		pr_err("cannot find partition: '%s'\n", cmd);
+		fastboot_fail("cannot find partition");
+		return;
+	}
+
+	if (is_sparse_image(download_buffer)) {
+		struct fb_mmc_sparse sparse_priv;
+		struct sparse_storage sparse;
+		int err;
+
+		sparse_priv.dev_desc = dev_desc;
+
+		sparse.blksz = info.blksz;
+		sparse.start = info.start;
+		sparse.size = info.size;
+		sparse.write = fb_mmc_sparse_write;
+		sparse.reserve = fb_mmc_sparse_reserve;
+		sparse.mssg = fastboot_fail;
+
+		printf("Flashing sparse image at offset " LBAFU "\n",
+		       sparse.start);
+
+		sparse.priv = &sparse_priv;
+		err = write_sparse_image(&sparse, cmd, download_buffer);
+		if (!err)
+			fastboot_okay("");
+	} else {
+		write_raw_image(dev_desc, &info, cmd, download_buffer,
+				download_bytes);
+	}
+}
+
+void fb_mmc_erase(const char *cmd)
+{
+	int ret;
+	struct blk_desc *dev_desc;
+	disk_partition_t info;
+	lbaint_t blks, blks_start, blks_size, grp_size;
+	struct mmc *mmc = find_mmc_device(CONFIG_FASTBOOT_FLASH_MMC_DEV);
+
+	if (mmc == NULL) {
+		pr_err("invalid mmc device");
+		fastboot_fail("invalid mmc device");
+		return;
+	}
+
+	dev_desc = blk_get_dev("mmc", CONFIG_FASTBOOT_FLASH_MMC_DEV);
+	if (!dev_desc || dev_desc->type == DEV_TYPE_UNKNOWN) {
+		pr_err("invalid mmc device");
+		fastboot_fail("invalid mmc device");
+		return;
+	}
+
+	ret = part_get_info_by_name_or_alias(dev_desc, cmd, &info);
+	if (ret < 0) {
+		pr_err("cannot find partition: '%s'", cmd);
+		fastboot_fail("cannot find partition");
+		return;
+	}
+
+	/* Align blocks to erase group size to avoid erasing other partitions */
+	grp_size = mmc->erase_grp_size;
+	blks_start = (info.start + grp_size - 1) & ~(grp_size - 1);
+	if (info.size >= grp_size)
+		blks_size = (info.size - (blks_start - info.start)) &
+				(~(grp_size - 1));
+	else
+		blks_size = 0;
+
+	printf("Erasing blocks " LBAFU " to " LBAFU " due to alignment\n",
+	       blks_start, blks_start + blks_size);
+
+	blks = blk_derase(dev_desc, blks_start, blks_size);
+	if (blks != blks_size) {
+		pr_err("failed erasing from device %d", dev_desc->devnum);
+		fastboot_fail("failed erasing from device");
+		return;
+	}
+
+	printf("........ erased " LBAFU " bytes from '%s'\n",
+	       blks_size * info.blksz, cmd);
+	fastboot_okay("");
+}
diff --git a/drivers/fastboot/fb_nand.c b/drivers/fastboot/fb_nand.c
new file mode 100644
index 0000000000..c07655e49e
--- /dev/null
+++ b/drivers/fastboot/fb_nand.c
@@ -0,0 +1,230 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright 2014 Broadcom Corporation.
+ * Copyright 2015 Free Electrons.
+ */
+
+#include <config.h>
+#include <common.h>
+
+#include <fastboot.h>
+#include <image-sparse.h>
+
+#include <linux/mtd/mtd.h>
+#include <jffs2/jffs2.h>
+#include <nand.h>
+
+struct fb_nand_sparse {
+	struct mtd_info		*mtd;
+	struct part_info	*part;
+};
+
+__weak int board_fastboot_erase_partition_setup(char *name)
+{
+	return 0;
+}
+
+__weak int board_fastboot_write_partition_setup(char *name)
+{
+	return 0;
+}
+
+static int fb_nand_lookup(const char *partname,
+			  struct mtd_info **mtd,
+			  struct part_info **part)
+{
+	struct mtd_device *dev;
+	int ret;
+	u8 pnum;
+
+	ret = mtdparts_init();
+	if (ret) {
+		pr_err("Cannot initialize MTD partitions\n");
+		fastboot_fail("cannot init mtdparts");
+		return ret;
+	}
+
+	ret = find_dev_and_part(partname, &dev, &pnum, part);
+	if (ret) {
+		pr_err("cannot find partition: '%s'", partname);
+		fastboot_fail("cannot find partition");
+		return ret;
+	}
+
+	if (dev->id->type != MTD_DEV_TYPE_NAND) {
+		pr_err("partition '%s' is not stored on a NAND device",
+		      partname);
+		fastboot_fail("not a NAND device");
+		return -EINVAL;
+	}
+
+	*mtd = get_nand_dev_by_index(dev->id->num);
+
+	return 0;
+}
+
+static int _fb_nand_erase(struct mtd_info *mtd, struct part_info *part)
+{
+	nand_erase_options_t opts;
+	int ret;
+
+	memset(&opts, 0, sizeof(opts));
+	opts.offset = part->offset;
+	opts.length = part->size;
+	opts.quiet = 1;
+
+	printf("Erasing blocks 0x%llx to 0x%llx\n",
+	       part->offset, part->offset + part->size);
+
+	ret = nand_erase_opts(mtd, &opts);
+	if (ret)
+		return ret;
+
+	printf("........ erased 0x%llx bytes from '%s'\n",
+	       part->size, part->name);
+
+	return 0;
+}
+
+static int _fb_nand_write(struct mtd_info *mtd, struct part_info *part,
+			  void *buffer, unsigned int offset,
+			  unsigned int length, size_t *written)
+{
+	int flags = WITH_WR_VERIFY;
+
+#ifdef CONFIG_FASTBOOT_FLASH_NAND_TRIMFFS
+	flags |= WITH_DROP_FFS;
+#endif
+
+	return nand_write_skip_bad(mtd, offset, &length, written,
+				   part->size - (offset - part->offset),
+				   buffer, flags);
+}
+
+static lbaint_t fb_nand_sparse_write(struct sparse_storage *info,
+		lbaint_t blk, lbaint_t blkcnt, const void *buffer)
+{
+	struct fb_nand_sparse *sparse = info->priv;
+	size_t written;
+	int ret;
+
+	ret = _fb_nand_write(sparse->mtd, sparse->part, (void *)buffer,
+			     blk * info->blksz,
+			     blkcnt * info->blksz, &written);
+	if (ret < 0) {
+		printf("Failed to write sparse chunk\n");
+		return ret;
+	}
+
+/* TODO - verify that the value "written" includes the "bad-blocks" ... */
+
+	/*
+	 * the return value must be 'blkcnt' ("good-blocks") plus the
+	 * number of "bad-blocks" encountered within this space...
+	 */
+	return written / info->blksz;
+}
+
+static lbaint_t fb_nand_sparse_reserve(struct sparse_storage *info,
+		lbaint_t blk, lbaint_t blkcnt)
+{
+	int bad_blocks = 0;
+
+/*
+ * TODO - implement a function to determine the total number
+ * of blocks which must be used in order to reserve the specified
+ * number ("blkcnt") of "good-blocks", starting at "blk"...
+ * ( possibly something like the "check_skip_len()" function )
+ */
+
+	/*
+	 * the return value must be 'blkcnt' ("good-blocks") plus the
+	 * number of "bad-blocks" encountered within this space...
+	 */
+	return blkcnt + bad_blocks;
+}
+
+void fb_nand_flash_write(const char *cmd, void *download_buffer,
+			 unsigned int download_bytes)
+{
+	struct part_info *part;
+	struct mtd_info *mtd = NULL;
+	int ret;
+
+	ret = fb_nand_lookup(cmd, &mtd, &part);
+	if (ret) {
+		pr_err("invalid NAND device");
+		fastboot_fail("invalid NAND device");
+		return;
+	}
+
+	ret = board_fastboot_write_partition_setup(part->name);
+	if (ret)
+		return;
+
+	if (is_sparse_image(download_buffer)) {
+		struct fb_nand_sparse sparse_priv;
+		struct sparse_storage sparse;
+
+		sparse_priv.mtd = mtd;
+		sparse_priv.part = part;
+
+		sparse.blksz = mtd->writesize;
+		sparse.start = part->offset / sparse.blksz;
+		sparse.size = part->size / sparse.blksz;
+		sparse.write = fb_nand_sparse_write;
+		sparse.reserve = fb_nand_sparse_reserve;
+		sparse.mssg = fastboot_fail;
+
+		printf("Flashing sparse image at offset " LBAFU "\n",
+		       sparse.start);
+
+		sparse.priv = &sparse_priv;
+		ret = write_sparse_image(&sparse, cmd, download_buffer);
+		if (!ret)
+			fastboot_okay("");
+	} else {
+		printf("Flashing raw image at offset 0x%llx\n",
+		       part->offset);
+
+		ret = _fb_nand_write(mtd, part, download_buffer, part->offset,
+				     download_bytes, NULL);
+
+		printf("........ wrote %u bytes to '%s'\n",
+		       download_bytes, part->name);
+	}
+
+	if (ret) {
+		fastboot_fail("error writing the image");
+		return;
+	}
+
+	fastboot_okay("");
+}
+
+void fb_nand_erase(const char *cmd)
+{
+	struct part_info *part;
+	struct mtd_info *mtd = NULL;
+	int ret;
+
+	ret = fb_nand_lookup(cmd, &mtd, &part);
+	if (ret) {
+		pr_err("invalid NAND device");
+		fastboot_fail("invalid NAND device");
+		return;
+	}
+
+	ret = board_fastboot_erase_partition_setup(part->name);
+	if (ret)
+		return;
+
+	ret = _fb_nand_erase(mtd, part);
+	if (ret) {
+		pr_err("failed erasing from device %s", mtd->name);
+		fastboot_fail("failed erasing from device");
+		return;
+	}
+
+	fastboot_okay("");
+}