[PATCH RFT v6 0/3] fastboot: add support for generic block flashing

[PATCH RFT v6 0/3] fastboot: add support for generic block flashing

[Neil Armstrong]

This serie permits using any block device as target
for fastboot by moving the generic block logic into
a common set of helpers and also use them as generic
backend.

The erase logic has been extended to support software
erase since only 2 block drivers exposes the erase
operation.

Tests are welcome to make sure this series doesn't
introduce any regressions on the emmc backend.

Before and after patchset:
$ tools/qconfig.py -f FASTBOOT ARCH_SUNXI BLK ~FASTBOOT_FLASH
 1 matches
 CHIP

The CHIP board disables MMC and had FASTBOOT_BLK disabled to
save memory, but adding the BLK dependency made FASTBOOT_FLASH_BLOCK
enabled on boards that didn't want FASTBOOT_FLASH enabled at all.

Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
---
Changes in v6:
- Fix BLK dependency that can affect SUNXI board with MMC/NAND disabled
- Link to v5: https://lore.kernel.org/r/20250606-topic-fastboot-blk-v5-0-203538ec5b32@linaro.org

Changes in v5:
- Removed BLK dependency on FASTBOOT_FLASH_MMC
- Removed BLK dependency on FASTBOOT_FLASH in patch 2
- Added back BLK dependency on FASTBOOT_FLASH in patch 3
- Rewrote FASTBOOT_FLASH_BLOCK_INTERFACE_ID help text with Tom suggestions
- Removed default for FASTBOOT_FLASH_BLOCK_INTERFACE_NAME
- CI test run is fixed with FASTBOOT_FLASH_BLOCK_INTERFACE_ID default to 0
- Link to v4: https://lore.kernel.org/r/20250522-topic-fastboot-blk-v4-0-af7f7f30564d@linaro.org

Changes in v4:
- Rebase on next
- Fixup Kconfig default values & description
- Link to v3: https://lore.kernel.org/r/20250506-topic-fastboot-blk-v3-0-d94be5829f46@linaro.org

Changes in v3:
- Move Kconfig/Makefile changes over the 2 patches
- Relicence to GPL2 with Dmitrii approval
- Move soft erase in a separate function
- Update help text of Kconfig BLOCK entries
- Add warning at init if MMC was selected with BLOCK backend
- Link to v2: https://lore.kernel.org/r/20250409-topic-fastboot-blk-v2-0-c676f21d414f@linaro.org

Changes in v2:
- Dropped applied virtio erase patch
- Reorganize patches, introducing helpers first, using them in mmc afterwards
- Added soft-erase logic
- Added move helpers to handle the partitions erase & flash from emmc
- Fixed const var on last patch
- Link to v1: https://lore.kernel.org/all/20240306185921.1854109-1-dimorinny@google.com/

---
Dmitrii Merkurev (3):
      fastboot: blk: introduce fastboot block flashing support
      fastboot: blk: switch emmc to use the block helpers
      fastboot: integrate block flashing back-end

 drivers/fastboot/Kconfig      |  32 ++++-
 drivers/fastboot/Makefile     |   4 +-
 drivers/fastboot/fb_block.c   | 323 ++++++++++++++++++++++++++++++++++++++++++
 drivers/fastboot/fb_command.c |   8 ++
 drivers/fastboot/fb_common.c  |  22 ++-
 drivers/fastboot/fb_getvar.c  |   8 +-
 drivers/fastboot/fb_mmc.c     | 210 ++-------------------------
 include/fb_block.h            | 105 ++++++++++++++
 8 files changed, 506 insertions(+), 206 deletions(-)
---
base-commit: f2220962f9cb1366bfc003ec2cc5650499c68895
change-id: 20250408-topic-fastboot-blk-c5e14cd59224

Best regards,
-- 
Neil Armstrong <neil.armstrong@linaro.org>

[PATCH RFT v6 1/3] fastboot: blk: introduce fastboot block flashing support

[Neil Armstrong]

From: Dmitrii Merkurev <dimorinny@google.com>

Introduce fastboot block flashing functions and helpers
to be shared with the MMC implementation.

The write logic comes from the mmc implementation, while
the partition lookup is much simpler and could be extended.

For the erase logic, allmost no block drivers exposes the
erase operation, except mmc & virtio, so in order to allow
erasiong any partition a soft-erase logic has been added
to write zero-ed buffers in a loop.

Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
Tested-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
---
 drivers/fastboot/fb_block.c | 323 ++++++++++++++++++++++++++++++++++++++++++++
 include/fb_block.h          | 105 ++++++++++++++
 2 files changed, 428 insertions(+)

diff --git a/drivers/fastboot/fb_block.c b/drivers/fastboot/fb_block.c
new file mode 100644
index 0000000000000000000000000000000000000000..b725397c91af2717812e69e2b624076eb30f781d
--- /dev/null
+++ b/drivers/fastboot/fb_block.c
@@ -0,0 +1,323 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ */
+
+#include <blk.h>
+#include <div64.h>
+#include <fastboot-internal.h>
+#include <fastboot.h>
+#include <fb_block.h>
+#include <image-sparse.h>
+#include <part.h>
+#include <malloc.h>
+
+/**
+ * FASTBOOT_MAX_BLOCKS_ERASE - maximum blocks to erase per derase call
+ *
+ * in the ERASE case we can have much larger buffer size since
+ * we're not transferring an actual buffer
+ */
+#define FASTBOOT_MAX_BLOCKS_ERASE 1048576
+/**
+ * FASTBOOT_MAX_BLOCKS_SOFT_ERASE - maximum blocks to software erase at once
+ */
+#define FASTBOOT_MAX_BLOCKS_SOFT_ERASE 4096
+/**
+ * FASTBOOT_MAX_BLOCKS_WRITE - maximum blocks to write per dwrite call
+ */
+#define FASTBOOT_MAX_BLOCKS_WRITE 65536
+
+struct fb_block_sparse {
+	struct blk_desc	*dev_desc;
+};
+
+/* Write 0s instead of using erase operation, inefficient but functional */
+static lbaint_t fb_block_soft_erase(struct blk_desc *block_dev, lbaint_t blk,
+				    lbaint_t cur_blkcnt, lbaint_t erase_buf_blks,
+				    void *erase_buffer)
+{
+	lbaint_t blks_written = 0;
+	int j;
+
+	memset(erase_buffer, 0, erase_buf_blks * block_dev->blksz);
+
+	for (j = 0; j < cur_blkcnt; j += erase_buf_blks) {
+		lbaint_t remain = min_t(lbaint_t, cur_blkcnt - j,
+				erase_buf_blks);
+
+		blks_written += blk_dwrite(block_dev, blk + j,
+				remain, erase_buffer);
+		printf(".");
+	}
+
+	return blks_written;
+}
+
+static lbaint_t fb_block_write(struct blk_desc *block_dev, lbaint_t start,
+			       lbaint_t blkcnt, const void *buffer)
+{
+	lbaint_t blk = start;
+	lbaint_t blks_written = 0;
+	lbaint_t cur_blkcnt = 0;
+	lbaint_t blks = 0;
+	void *erase_buf = NULL;
+	int erase_buf_blks = 0;
+	int step = buffer ? FASTBOOT_MAX_BLOCKS_WRITE : FASTBOOT_MAX_BLOCKS_ERASE;
+	int i;
+
+	for (i = 0; i < blkcnt; i += step) {
+		cur_blkcnt = min((int)blkcnt - i, step);
+		if (buffer) {
+			if (fastboot_progress_callback)
+				fastboot_progress_callback("writing");
+			blks_written = blk_dwrite(block_dev, blk, cur_blkcnt,
+						  buffer + (i * block_dev->blksz));
+		} else {
+			if (fastboot_progress_callback)
+				fastboot_progress_callback("erasing");
+
+			if (!erase_buf) {
+				blks_written = blk_derase(block_dev, blk, cur_blkcnt);
+
+				/* Allocate erase buffer if erase is not implemented */
+				if ((long)blks_written == -ENOSYS) {
+					erase_buf_blks = min_t(long, blkcnt,
+							       FASTBOOT_MAX_BLOCKS_SOFT_ERASE);
+					erase_buf = malloc(erase_buf_blks * block_dev->blksz);
+
+					printf("Slowly writing empty buffers due to missing erase operation\n");
+				}
+			}
+
+			if (erase_buf)
+				blks_written = fb_block_soft_erase(block_dev, blk, cur_blkcnt,
+								   erase_buf_blks, erase_buf);
+		}
+		blk += blks_written;
+		blks += blks_written;
+	}
+
+	if (erase_buf)
+		free(erase_buf);
+
+	return blks;
+}
+
+static lbaint_t fb_block_sparse_write(struct sparse_storage *info,
+				      lbaint_t blk, lbaint_t blkcnt,
+				      const void *buffer)
+{
+	struct fb_block_sparse *sparse = info->priv;
+	struct blk_desc *dev_desc = sparse->dev_desc;
+
+	return fb_block_write(dev_desc, blk, blkcnt, buffer);
+}
+
+static lbaint_t fb_block_sparse_reserve(struct sparse_storage *info,
+					lbaint_t blk, lbaint_t blkcnt)
+{
+	return blkcnt;
+}
+
+int fastboot_block_get_part_info(const char *part_name,
+				 struct blk_desc **dev_desc,
+				 struct disk_partition *part_info,
+				 char *response)
+{
+	int ret;
+	const char *interface = config_opt_enabled(CONFIG_FASTBOOT_FLASH_BLOCK,
+						   CONFIG_FASTBOOT_FLASH_BLOCK_INTERFACE_NAME,
+						   NULL);
+	const int device = config_opt_enabled(CONFIG_FASTBOOT_FLASH_BLOCK,
+					      CONFIG_FASTBOOT_FLASH_BLOCK_DEVICE_ID, -1);
+
+	if (!part_name || !strcmp(part_name, "")) {
+		fastboot_fail("partition not given", response);
+		return -ENOENT;
+	}
+	if (!interface || !strcmp(interface, "")) {
+		fastboot_fail("block interface isn't provided", response);
+		return -EINVAL;
+	}
+
+	*dev_desc = blk_get_dev(interface, device);
+	if (!dev_desc) {
+		fastboot_fail("no such device", response);
+		return -ENODEV;
+	}
+
+	ret = part_get_info_by_name(*dev_desc, part_name, part_info);
+	if (ret < 0)
+		fastboot_fail("failed to get partition info", response);
+
+	return ret;
+}
+
+void fastboot_block_raw_erase_disk(struct blk_desc *dev_desc, const char *disk_name,
+				   char *response)
+{
+	lbaint_t written;
+
+	debug("Start Erasing %s...\n", disk_name);
+
+	written = fb_block_write(dev_desc, 0, dev_desc->lba, NULL);
+	if (written != dev_desc->lba) {
+		pr_err("Failed to erase %s\n", disk_name);
+		fastboot_response("FAIL", response, "Failed to erase %s", disk_name);
+		return;
+	}
+
+	printf("........ erased " LBAFU " bytes from '%s'\n",
+	       dev_desc->lba * dev_desc->blksz, disk_name);
+	fastboot_okay(NULL, response);
+}
+
+void fastboot_block_raw_erase(struct blk_desc *dev_desc, struct disk_partition *info,
+			      const char *part_name, uint alignment, char *response)
+{
+	lbaint_t written, blks_start, blks_size;
+
+	if (alignment) {
+		blks_start = (info->start + alignment - 1) & ~(alignment - 1);
+		if (info->size >= alignment)
+			blks_size = (info->size - (blks_start - info->start)) &
+				(~(alignment - 1));
+		else
+			blks_size = 0;
+
+		printf("Erasing blocks " LBAFU " to " LBAFU " due to alignment\n",
+		       blks_start, blks_start + blks_size);
+	} else {
+		blks_start = info->start;
+		blks_size = info->size;
+	}
+
+	written = fb_block_write(dev_desc, blks_start, blks_size, NULL);
+	if (written != blks_size) {
+		fastboot_fail("failed to erase partition", response);
+		return;
+	}
+
+	printf("........ erased " LBAFU " bytes from '%s'\n",
+	       blks_size * info->blksz, part_name);
+	fastboot_okay(NULL, response);
+}
+
+void fastboot_block_erase(const char *part_name, char *response)
+{
+	struct blk_desc *dev_desc;
+	struct disk_partition part_info;
+
+	if (fastboot_block_get_part_info(part_name, &dev_desc, &part_info, response) < 0)
+		return;
+
+	fastboot_block_raw_erase(dev_desc, &part_info, part_name, 0, response);
+}
+
+void fastboot_block_write_raw_disk(struct blk_desc *dev_desc, const char *disk_name,
+				   void *buffer, u32 download_bytes, char *response)
+{
+	lbaint_t blkcnt;
+	lbaint_t blks;
+
+	/* determine number of blocks to write */
+	blkcnt = ((download_bytes + (dev_desc->blksz - 1)) & ~(dev_desc->blksz - 1));
+	blkcnt = lldiv(blkcnt, dev_desc->blksz);
+
+	if (blkcnt > dev_desc->lba) {
+		pr_err("too large for disk: '%s'\n", disk_name);
+		fastboot_fail("too large for disk", response);
+		return;
+	}
+
+	printf("Flashing Raw Image\n");
+
+	blks = fb_block_write(dev_desc, 0, blkcnt, buffer);
+
+	if (blks != blkcnt) {
+		pr_err("failed writing to %s\n", disk_name);
+		fastboot_fail("failed writing to device", response);
+		return;
+	}
+
+	printf("........ wrote " LBAFU " bytes to '%s'\n", blkcnt * dev_desc->blksz,
+	       disk_name);
+	fastboot_okay(NULL, response);
+}
+
+void fastboot_block_write_raw_image(struct blk_desc *dev_desc,
+				    struct disk_partition *info, const char *part_name,
+				    void *buffer, u32 download_bytes, char *response)
+{
+	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", response);
+		return;
+	}
+
+	printf("Flashing Raw Image\n");
+
+	blks = fb_block_write(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", response);
+		return;
+	}
+
+	printf("........ wrote " LBAFU " bytes to '%s'\n", blkcnt * info->blksz,
+	       part_name);
+	fastboot_okay(NULL, response);
+}
+
+void fastboot_block_write_sparse_image(struct blk_desc *dev_desc, struct disk_partition *info,
+				       const char *part_name, void *buffer, char *response)
+{
+	struct fb_block_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_block_sparse_write;
+	sparse.reserve = fb_block_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, part_name, buffer,
+				 response);
+	if (!err)
+		fastboot_okay(NULL, response);
+}
+
+void fastboot_block_flash_write(const char *part_name, void *download_buffer,
+				u32 download_bytes, char *response)
+{
+	struct blk_desc *dev_desc;
+	struct disk_partition part_info;
+
+	if (fastboot_block_get_part_info(part_name, &dev_desc, &part_info, response) < 0)
+		return;
+
+	if (is_sparse_image(download_buffer)) {
+		fastboot_block_write_sparse_image(dev_desc, &part_info, part_name,
+						  download_buffer, response);
+	} else {
+		fastboot_block_write_raw_image(dev_desc, &part_info, part_name,
+					       download_buffer, download_bytes, response);
+	}
+}
diff --git a/include/fb_block.h b/include/fb_block.h
new file mode 100644
index 0000000000000000000000000000000000000000..189c708e2f0eaccf4871f68f93c8d38eabc4349a
--- /dev/null
+++ b/include/fb_block.h
@@ -0,0 +1,105 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ */
+
+#ifndef _FB_BLOCK_H_
+#define _FB_BLOCK_H_
+
+struct blk_desc;
+struct disk_partition;
+
+/**
+ * fastboot_block_get_part_info() - Lookup block partition by name
+ *
+ * @part_name: Named partition to lookup
+ * @dev_desc: Pointer to returned blk_desc pointer
+ * @part_info: Pointer to returned struct disk_partition
+ * @response: Pointer to fastboot response buffer
+ * Return: 0 on success, -ve on error
+ */
+int fastboot_block_get_part_info(const char *part_name,
+				 struct blk_desc **dev_desc,
+				 struct disk_partition *part_info,
+				 char *response);
+
+/**
+ * fastboot_block_raw_erase() - Erase raw block device partition
+ *
+ * @dev_desc: Block device we're going write to
+ * @info: Partition we're going write to
+ * @part_name: Name of partition we're going write to
+ * @alignment: erase start and size alignment, specify 0 to ignore
+ * @response: Pointer to fastboot response buffer
+ */
+void fastboot_block_raw_erase(struct blk_desc *dev_desc, struct disk_partition *info,
+			      const char *part_name, uint alignment, char *response);
+
+/**
+ * fastboot_block_raw_erase_disk() - Erase raw block device
+ *
+ * @dev_desc: Block device we're going write to
+ * @disk_name: Name of disk we're going write to
+ * @response: Pointer to fastboot response buffer
+ */
+void fastboot_block_raw_erase_disk(struct blk_desc *dev_desc, const char *disk_name,
+				   char *response);
+
+/**
+ * fastboot_block_erase() - Erase partition on block device for fastboot
+ *
+ * @part_name: Named partition to erase
+ * @response: Pointer to fastboot response buffer
+ */
+void fastboot_block_erase(const char *part_name, char *response);
+
+/**
+ * fastboot_block_write_raw_disk() - Write raw image to block device
+ *
+ * @dev_desc: Block device we're going write to
+ * @disk_name: Name of disk we're going write to
+ * @buffer: Downloaded buffer pointer
+ * @download_bytes: Size of content on downloaded buffer pointer
+ * @response: Pointer to fastboot response buffer
+ */
+void fastboot_block_write_raw_disk(struct blk_desc *dev_desc, const char *disk_name,
+				   void *buffer, u32 download_bytes, char *response);
+
+/**
+ * fastboot_block_write_raw_image() - Write raw image to block device partition
+ *
+ * @dev_desc: Block device we're going write to
+ * @info: Partition we're going write to
+ * @part_name: Name of partition we're going write to
+ * @buffer: Downloaded buffer pointer
+ * @download_bytes: Size of content on downloaded buffer pointer
+ * @response: Pointer to fastboot response buffer
+ */
+void fastboot_block_write_raw_image(struct blk_desc *dev_desc,
+				    struct disk_partition *info, const char *part_name,
+				    void *buffer, u32 download_bytes, char *response);
+
+/**
+ * fastboot_block_write_sparse_image() - Write sparse image to block device partition
+ *
+ * @dev_desc: Block device we're going write to
+ * @info: Partition we're going write to
+ * @part_name: Name of partition we're going write to
+ * @buffer: Downloaded buffer pointer
+ * @response: Pointer to fastboot response buffer
+ */
+void fastboot_block_write_sparse_image(struct blk_desc *dev_desc, struct disk_partition *info,
+				       const char *part_name, void *buffer, char *response);
+
+/**
+ * fastboot_block_flash_write() - Write image to block device for fastboot
+ *
+ * @part_name: Named partition to write image to
+ * @download_buffer: Pointer to image data
+ * @download_bytes: Size of image data
+ * @response: Pointer to fastboot response buffer
+ */
+void fastboot_block_flash_write(const char *part_name, void *download_buffer,
+				u32 download_bytes, char *response);
+
+#endif // _FB_BLOCK_H_

-- 
2.34.1

[PATCH RFT v6 2/3] fastboot: blk: switch emmc to use the block helpers

[Neil Armstrong]

From: Dmitrii Merkurev <dimorinny@google.com>

Switch the mmc backend to this new shared block helpers,
reducing block logic and only leaving MMC specific logic.

Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
Tested-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
---
 drivers/fastboot/Makefile |   3 +-
 drivers/fastboot/fb_mmc.c | 210 +++-------------------------------------------
 2 files changed, 14 insertions(+), 199 deletions(-)

diff --git a/drivers/fastboot/Makefile b/drivers/fastboot/Makefile
index 048af5aa823436956142a536c5f7dcf1a8948726..c2214c968ab357371f5d3d27ecc9c1a3e9404e89 100644
--- a/drivers/fastboot/Makefile
+++ b/drivers/fastboot/Makefile
@@ -3,5 +3,6 @@
 obj-y += fb_common.o
 obj-y += fb_getvar.o
 obj-y += fb_command.o
-obj-$(CONFIG_FASTBOOT_FLASH_MMC) += fb_mmc.o
+# MMC reuses block implementation
+obj-$(CONFIG_FASTBOOT_FLASH_MMC) += fb_block.o fb_mmc.o
 obj-$(CONFIG_FASTBOOT_FLASH_NAND) += fb_nand.o
diff --git a/drivers/fastboot/fb_mmc.c b/drivers/fastboot/fb_mmc.c
index dca7c222f35659b22d327541b245760a6a6d7b35..11d9c8e84602c7434733c060b84c91c38772ac9f 100644
--- a/drivers/fastboot/fb_mmc.c
+++ b/drivers/fastboot/fb_mmc.c
@@ -8,6 +8,7 @@
 #include <env.h>
 #include <fastboot.h>
 #include <fastboot-internal.h>
+#include <fb_block.h>
 #include <fb_mmc.h>
 #include <image-sparse.h>
 #include <image.h>
@@ -20,10 +21,6 @@
 
 #define BOOT_PARTITION_NAME "boot"
 
-struct fb_mmc_sparse {
-	struct blk_desc	*dev_desc;
-};
-
 static int raw_part_get_info_by_name(struct blk_desc *dev_desc,
 				     const char *name,
 				     struct disk_partition *info)
@@ -114,118 +111,10 @@ static int part_get_info_by_name_or_alias(struct blk_desc **dev_desc,
 	return do_get_part_info(dev_desc, name, info);
 }
 
-/**
- * fb_mmc_blk_write() - Write/erase MMC in chunks of FASTBOOT_MAX_BLK_WRITE
- *
- * @block_dev: Pointer to block device
- * @start: First block to write/erase
- * @blkcnt: Count of blocks
- * @buffer: Pointer to data buffer for write or NULL for erase
- */
-static lbaint_t fb_mmc_blk_write(struct blk_desc *block_dev, lbaint_t start,
-				 lbaint_t blkcnt, const void *buffer)
-{
-	lbaint_t blk = start;
-	lbaint_t blks_written;
-	lbaint_t cur_blkcnt;
-	lbaint_t blks = 0;
-	int i;
-
-	for (i = 0; i < blkcnt; i += FASTBOOT_MAX_BLK_WRITE) {
-		cur_blkcnt = min((int)blkcnt - i, FASTBOOT_MAX_BLK_WRITE);
-		if (buffer) {
-			if (fastboot_progress_callback)
-				fastboot_progress_callback("writing");
-			blks_written = blk_dwrite(block_dev, blk, cur_blkcnt,
-						  buffer + (i * block_dev->blksz));
-		} else {
-			if (fastboot_progress_callback)
-				fastboot_progress_callback("erasing");
-			blks_written = blk_derase(block_dev, blk, cur_blkcnt);
-		}
-		blk += blks_written;
-		blks += blks_written;
-	}
-	return blks;
-}
-
-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 fb_mmc_blk_write(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,
-			    struct disk_partition *info, const char *part_name,
-			    void *buffer, u32 download_bytes, char *response)
-{
-	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", response);
-		return;
-	}
-
-	puts("Flashing Raw Image\n");
-
-	blks = fb_mmc_blk_write(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", response);
-		return;
-	}
-
-	printf("........ wrote " LBAFU " bytes to '%s'\n", blkcnt * info->blksz,
-	       part_name);
-	fastboot_okay(NULL, response);
-}
-
-#if defined(CONFIG_FASTBOOT_MMC_BOOT_SUPPORT) || \
-	defined(CONFIG_FASTBOOT_MMC_USER_SUPPORT)
-static int fb_mmc_erase_mmc_hwpart(struct blk_desc *dev_desc)
-{
-	lbaint_t blks;
-
-	debug("Start Erasing mmc hwpart[%u]...\n", dev_desc->hwpart);
-
-	blks = fb_mmc_blk_write(dev_desc, 0, dev_desc->lba, NULL);
-
-	if (blks != dev_desc->lba) {
-		pr_err("Failed to erase mmc hwpart[%u]\n", dev_desc->hwpart);
-		return 1;
-	}
-
-	printf("........ erased %llu bytes from mmc hwpart[%u]\n",
-	       (u64)(dev_desc->lba * dev_desc->blksz), dev_desc->hwpart);
-
-	return 0;
-}
-#endif
-
 #ifdef CONFIG_FASTBOOT_MMC_BOOT_SUPPORT
 static void fb_mmc_boot_ops(struct blk_desc *dev_desc, void *buffer,
 			    int hwpart, u32 buff_sz, char *response)
 {
-	lbaint_t blkcnt;
-	lbaint_t blks;
-	unsigned long blksz;
-
 	// To operate on EMMC_BOOT1/2 (mmc0boot0/1) we first change the hwpart
 	if (blk_dselect_hwpart(dev_desc, hwpart)) {
 		pr_err("Failed to select hwpart\n");
@@ -233,42 +122,11 @@ static void fb_mmc_boot_ops(struct blk_desc *dev_desc, void *buffer,
 		return;
 	}
 
-	if (buffer) { /* flash */
-
-		/* determine number of blocks to write */
-		blksz = dev_desc->blksz;
-		blkcnt = ((buff_sz + (blksz - 1)) & ~(blksz - 1));
-		blkcnt = lldiv(blkcnt, blksz);
-
-		if (blkcnt > dev_desc->lba) {
-			pr_err("Image size too large\n");
-			fastboot_fail("Image size too large", response);
-			return;
-		}
-
-		debug("Start Flashing Image to EMMC_BOOT%d...\n", hwpart);
-
-		blks = fb_mmc_blk_write(dev_desc, 0, blkcnt, buffer);
-
-		if (blks != blkcnt) {
-			pr_err("Failed to write EMMC_BOOT%d\n", hwpart);
-			fastboot_fail("Failed to write EMMC_BOOT part",
-				      response);
-			return;
-		}
-
-		printf("........ wrote %llu bytes to EMMC_BOOT%d\n",
-		       (u64)(blkcnt * blksz), hwpart);
-	} else { /* erase */
-		if (fb_mmc_erase_mmc_hwpart(dev_desc)) {
-			pr_err("Failed to erase EMMC_BOOT%d\n", hwpart);
-			fastboot_fail("Failed to erase EMMC_BOOT part",
-				      response);
-			return;
-		}
-	}
-
-	fastboot_okay(NULL, response);
+	if (buffer) /* flash */
+		fastboot_block_write_raw_disk(dev_desc, "EMMC_BOOT",
+					      buffer, buff_sz, response);
+	else /* erase */
+		fastboot_block_raw_erase_disk(dev_desc, "EMMC_BOOT", response);
 }
 #endif
 
@@ -609,30 +467,11 @@ void fastboot_mmc_flash_write(const char *cmd, void *download_buffer,
 		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,
-					 response);
-		if (!err)
-			fastboot_okay(NULL, response);
+		fastboot_block_write_sparse_image(dev_desc, &info, cmd,
+						  download_buffer, response);
 	} else {
-		write_raw_image(dev_desc, &info, cmd, download_buffer,
-				download_bytes, response);
+		fastboot_block_write_raw_image(dev_desc, &info, cmd, download_buffer,
+					       download_bytes, response);
 	}
 }
 
@@ -646,7 +485,6 @@ void fastboot_mmc_erase(const char *cmd, char *response)
 {
 	struct blk_desc *dev_desc;
 	struct disk_partition info;
-	lbaint_t blks, blks_start, blks_size, grp_size;
 	struct mmc *mmc = find_mmc_device(CONFIG_FASTBOOT_FLASH_MMC_DEV);
 
 #ifdef CONFIG_FASTBOOT_MMC_BOOT_SUPPORT
@@ -673,10 +511,7 @@ void fastboot_mmc_erase(const char *cmd, char *response)
 		if (!dev_desc)
 			return;
 
-		if (fb_mmc_erase_mmc_hwpart(dev_desc))
-			fastboot_fail("Failed to erase EMMC_USER", response);
-		else
-			fastboot_okay(NULL, response);
+		fastboot_block_raw_erase_disk(dev_desc, "EMMC_USER", response);
 		return;
 	}
 #endif
@@ -685,26 +520,5 @@ void fastboot_mmc_erase(const char *cmd, char *response)
 		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 = fb_mmc_blk_write(dev_desc, blks_start, blks_size, NULL);
-
-	if (blks != blks_size) {
-		pr_err("failed erasing from device %d\n", dev_desc->devnum);
-		fastboot_fail("failed erasing from device", response);
-		return;
-	}
-
-	printf("........ erased " LBAFU " bytes from '%s'\n",
-	       blks_size * info.blksz, cmd);
-	fastboot_okay(NULL, response);
+	fastboot_block_raw_erase(dev_desc, &info, cmd, mmc->erase_grp_size, response);
 }

-- 
2.34.1

[PATCH RFT v6 3/3] fastboot: integrate block flashing back-end

[Neil Armstrong]

From: Dmitrii Merkurev <dimorinny@google.com>

1. Get partition info/size
2. Erase partition
3. Flash partition
4. BCB

Make FASTBOOT_FLASH also depend on BLK, but make sure
it doesn't affect SUNXI and ROCKCHIP platforms since they
default to y already.

Make it only default on SUNXI when MMC or NAND is enabled,
so it doesn't break the CHIP & Ninendo boards, and for ROCKCHIP
when MMC is enabled.

Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Tested-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
---
 drivers/fastboot/Kconfig      | 32 ++++++++++++++++++++++++++++++--
 drivers/fastboot/Makefile     |  1 +
 drivers/fastboot/fb_command.c |  8 ++++++++
 drivers/fastboot/fb_common.c  | 22 ++++++++++++++++++----
 drivers/fastboot/fb_getvar.c  |  8 +++++++-
 5 files changed, 64 insertions(+), 7 deletions(-)

diff --git a/drivers/fastboot/Kconfig b/drivers/fastboot/Kconfig
index 70207573de2bd0d56b4b7fa6f7e17fdc5803ba15..b2b20a2c5e430cccc49fd6c04d6fb8825b67ec04 100644
--- a/drivers/fastboot/Kconfig
+++ b/drivers/fastboot/Kconfig
@@ -90,8 +90,9 @@ config FASTBOOT_USB_DEV
 
 config FASTBOOT_FLASH
 	bool "Enable FASTBOOT FLASH command"
-	default y if ARCH_SUNXI || ARCH_ROCKCHIP
-	depends on MMC || (MTD_RAW_NAND && CMD_MTDPARTS)
+	default y if ARCH_SUNXI && ( MMC || MTD_RAW_NAND )
+	default y if ARCH_ROCKCHIP && MMC
+	depends on MMC || (MTD_RAW_NAND && CMD_MTDPARTS) || BLK
 	select IMAGE_SPARSE
 	help
 	  The fastboot protocol includes a "flash" command for writing
@@ -119,6 +120,10 @@ config FASTBOOT_FLASH_NAND
 	bool "FASTBOOT on NAND"
 	depends on MTD_RAW_NAND && CMD_MTDPARTS
 
+config FASTBOOT_FLASH_BLOCK
+	bool "FASTBOOT on block device"
+	depends on BLK
+
 endchoice
 
 config FASTBOOT_FLASH_MMC_DEV
@@ -193,6 +198,29 @@ config FASTBOOT_MMC_USER_NAME
 	  defined here.
 	  The default target name for erasing EMMC_USER is "mmc0".
 
+config FASTBOOT_FLASH_BLOCK_INTERFACE_NAME
+	string "Define FASTBOOT block interface name"
+	depends on FASTBOOT_FLASH_BLOCK
+	help
+	  The fastboot "flash" and "erase" commands support operations
+	  on any Block device, this should specify the block device name
+	  like ide, scsi, usb, sata, nvme, virtio, blkmap, mtd...
+	  The mmc block device type can be used but most of the features
+	  available in the FASTBOOT_MMC will be missing.
+	  Consider using FASTBOOT_MMC on a MMC block device until all
+	  features are migrated.
+
+config FASTBOOT_FLASH_BLOCK_DEVICE_ID
+	int "Define FASTBOOT block device identifier"
+	depends on FASTBOOT_FLASH_BLOCK
+	default 0
+	help
+	  The fastboot "flash" and "erase" commands support operations
+	  on any Block device, this should specify the block device
+	  identifier on the system, as a number.
+	  Device identifiers are numbered starting from 0 and the most
+	  common case is to use the first controller on the system.
+
 config FASTBOOT_GPT_NAME
 	string "Target name for updating GPT"
 	depends on FASTBOOT_FLASH_MMC && EFI_PARTITION
diff --git a/drivers/fastboot/Makefile b/drivers/fastboot/Makefile
index c2214c968ab357371f5d3d27ecc9c1a3e9404e89..91e98763e8eab84ccd9b8e5354ff1419f61ef372 100644
--- a/drivers/fastboot/Makefile
+++ b/drivers/fastboot/Makefile
@@ -3,6 +3,7 @@
 obj-y += fb_common.o
 obj-y += fb_getvar.o
 obj-y += fb_command.o
+obj-$(CONFIG_FASTBOOT_FLASH_BLOCK) += fb_block.o
 # MMC reuses block implementation
 obj-$(CONFIG_FASTBOOT_FLASH_MMC) += fb_block.o fb_mmc.o
 obj-$(CONFIG_FASTBOOT_FLASH_NAND) += fb_nand.o
diff --git a/drivers/fastboot/fb_command.c b/drivers/fastboot/fb_command.c
index 2cdbac50ac4a0ce501753e95c1918ffa5d11158d..e6aee13e01618ee6567bf00527d3df327ae06f1c 100644
--- a/drivers/fastboot/fb_command.c
+++ b/drivers/fastboot/fb_command.c
@@ -8,6 +8,7 @@
 #include <env.h>
 #include <fastboot.h>
 #include <fastboot-internal.h>
+#include <fb_block.h>
 #include <fb_mmc.h>
 #include <fb_nand.h>
 #include <part.h>
@@ -337,6 +338,10 @@ void fastboot_data_complete(char *response)
  */
 static void __maybe_unused flash(char *cmd_parameter, char *response)
 {
+	if (IS_ENABLED(CONFIG_FASTBOOT_FLASH_BLOCK))
+		fastboot_block_flash_write(cmd_parameter, fastboot_buf_addr,
+					   image_size, response);
+
 	if (IS_ENABLED(CONFIG_FASTBOOT_FLASH_MMC))
 		fastboot_mmc_flash_write(cmd_parameter, fastboot_buf_addr,
 					 image_size, response);
@@ -357,6 +362,9 @@ static void __maybe_unused flash(char *cmd_parameter, char *response)
  */
 static void __maybe_unused erase(char *cmd_parameter, char *response)
 {
+	if (IS_ENABLED(CONFIG_FASTBOOT_FLASH_BLOCK))
+		fastboot_block_erase(cmd_parameter, response);
+
 	if (IS_ENABLED(CONFIG_FASTBOOT_FLASH_MMC))
 		fastboot_mmc_erase(cmd_parameter, response);
 
diff --git a/drivers/fastboot/fb_common.c b/drivers/fastboot/fb_common.c
index 68f92c4b887c8442cc212b8613fb70c7251cdcdf..dac5528f80908bf5b1224284c9ecd492394e4f0e 100644
--- a/drivers/fastboot/fb_common.c
+++ b/drivers/fastboot/fb_common.c
@@ -97,16 +97,24 @@ int __weak fastboot_set_reboot_flag(enum fastboot_reboot_reason reason)
 		[FASTBOOT_REBOOT_REASON_FASTBOOTD] = "boot-fastboot",
 		[FASTBOOT_REBOOT_REASON_RECOVERY] = "boot-recovery"
 	};
-	const int mmc_dev = config_opt_enabled(CONFIG_FASTBOOT_FLASH_MMC,
-					       CONFIG_FASTBOOT_FLASH_MMC_DEV, -1);
 
-	if (!IS_ENABLED(CONFIG_FASTBOOT_FLASH_MMC))
+	int device = config_opt_enabled(CONFIG_FASTBOOT_FLASH_BLOCK,
+					CONFIG_FASTBOOT_FLASH_BLOCK_DEVICE_ID, -1);
+	if (device == -1) {
+		device = config_opt_enabled(CONFIG_FASTBOOT_FLASH_MMC,
+					    CONFIG_FASTBOOT_FLASH_MMC_DEV, -1);
+	}
+	const char *bcb_iface = config_opt_enabled(CONFIG_FASTBOOT_FLASH_BLOCK,
+						   CONFIG_FASTBOOT_FLASH_BLOCK_INTERFACE_NAME,
+						   "mmc");
+
+	if (device == -1)
 		return -EINVAL;
 
 	if (reason >= FASTBOOT_REBOOT_REASONS_COUNT)
 		return -EINVAL;
 
-	ret = bcb_find_partition_and_load("mmc", mmc_dev, "misc");
+	ret = bcb_find_partition_and_load(bcb_iface, device, "misc");
 	if (ret)
 		goto out;
 
@@ -226,8 +234,14 @@ void fastboot_set_progress_callback(void (*progress)(const char *msg))
  */
 void fastboot_init(void *buf_addr, u32 buf_size)
 {
+#if IS_ENABLED(CONFIG_FASTBOOT_FLASH_BLOCK)
+	if (!strcmp(CONFIG_FASTBOOT_FLASH_BLOCK_INTERFACE_NAME, "mmc"))
+		printf("Warning: the fastboot block backend features are limited, consider using the MMC backend\n");
+#endif
+
 	fastboot_buf_addr = buf_addr ? buf_addr :
 				       (void *)CONFIG_FASTBOOT_BUF_ADDR;
 	fastboot_buf_size = buf_size ? buf_size : CONFIG_FASTBOOT_BUF_SIZE;
 	fastboot_set_progress_callback(NULL);
+
 }
diff --git a/drivers/fastboot/fb_getvar.c b/drivers/fastboot/fb_getvar.c
index 9c2ce65a4e5bce0da6b18aa1b2818f7db556c528..f083b21c797dc7e55315f2cba017a4372483fa92 100644
--- a/drivers/fastboot/fb_getvar.c
+++ b/drivers/fastboot/fb_getvar.c
@@ -7,6 +7,7 @@
 #include <fastboot.h>
 #include <fastboot-internal.h>
 #include <fb_mmc.h>
+#include <fb_block.h>
 #include <fb_nand.h>
 #include <fs.h>
 #include <part.h>
@@ -114,7 +115,12 @@ static int getvar_get_part_info(const char *part_name, char *response,
 	struct disk_partition disk_part;
 	struct part_info *part_info;
 
-	if (IS_ENABLED(CONFIG_FASTBOOT_FLASH_MMC)) {
+	if (IS_ENABLED(CONFIG_FASTBOOT_FLASH_BLOCK)) {
+		r = fastboot_block_get_part_info(part_name, &dev_desc, &disk_part,
+						 response);
+		if (r >= 0 && size)
+			*size = disk_part.size * disk_part.blksz;
+	} else if (IS_ENABLED(CONFIG_FASTBOOT_FLASH_MMC)) {
 		r = fastboot_mmc_get_part_info(part_name, &dev_desc, &disk_part,
 					       response);
 		if (r >= 0 && size)

-- 
2.34.1

Re: [PATCH RFT v6 1/3] fastboot: blk: introduce fastboot block flashing support

[Lothar Waßmann]

Hi,

On Mon, 30 Jun 2025 17:19:57 +0200 Neil Armstrong wrote:
> From: Dmitrii Merkurev <dimorinny@google.com>
> 
> Introduce fastboot block flashing functions and helpers
> to be shared with the MMC implementation.
> 
> The write logic comes from the mmc implementation, while
> the partition lookup is much simpler and could be extended.
> 
> For the erase logic, allmost no block drivers exposes the
> erase operation, except mmc & virtio, so in order to allow
> erasiong any partition a soft-erase logic has been added
> to write zero-ed buffers in a loop.
> 
> Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>
> Reviewed-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
> Tested-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
> ---
>  drivers/fastboot/fb_block.c | 323 ++++++++++++++++++++++++++++++++++++++++++++
>  include/fb_block.h          | 105 ++++++++++++++
>  2 files changed, 428 insertions(+)
> 
> diff --git a/drivers/fastboot/fb_block.c b/drivers/fastboot/fb_block.c
> new file mode 100644
> index 0000000000000000000000000000000000000000..b725397c91af2717812e69e2b624076eb30f781d
> --- /dev/null
> +++ b/drivers/fastboot/fb_block.c
> @@ -0,0 +1,323 @@
> +// SPDX-License-Identifier: GPL-2.0+
> +/*
> + * Copyright (C) 2024 The Android Open Source Project
> + */
> +
> +#include <blk.h>
> +#include <div64.h>
> +#include <fastboot-internal.h>
> +#include <fastboot.h>
> +#include <fb_block.h>
> +#include <image-sparse.h>
> +#include <part.h>
> +#include <malloc.h>
>
The alphabet seems to be a difficult concept for programmers to
grasp... ;-)

> +/**
> + * FASTBOOT_MAX_BLOCKS_ERASE - maximum blocks to erase per derase call
> + *
> + * in the ERASE case we can have much larger buffer size since
> + * we're not transferring an actual buffer
> + */
> +#define FASTBOOT_MAX_BLOCKS_ERASE 1048576
> +/**
> + * FASTBOOT_MAX_BLOCKS_SOFT_ERASE - maximum blocks to software erase at once
> + */
> +#define FASTBOOT_MAX_BLOCKS_SOFT_ERASE 4096
> +/**
> + * FASTBOOT_MAX_BLOCKS_WRITE - maximum blocks to write per dwrite call
> + */
> +#define FASTBOOT_MAX_BLOCKS_WRITE 65536
> +
Why invent an arbitrary number here, when there is already
CONFIG_FASTBOOT_BUF_SIZE which could be used for this purpose?

> +struct fb_block_sparse {
> +	struct blk_desc	*dev_desc;
> +};
> +
> +/* Write 0s instead of using erase operation, inefficient but functional */
> +static lbaint_t fb_block_soft_erase(struct blk_desc *block_dev, lbaint_t blk,
> +				    lbaint_t cur_blkcnt, lbaint_t erase_buf_blks,
> +				    void *erase_buffer)
> +{
> +	lbaint_t blks_written = 0;
> +	int j;
>
lbaint_t to match the type of cur_blkcnt and prevent integer overflow
on 32bit systems!

> +
> +	memset(erase_buffer, 0, erase_buf_blks * block_dev->blksz);
> +
> +	for (j = 0; j < cur_blkcnt; j += erase_buf_blks) {
> +		lbaint_t remain = min_t(lbaint_t, cur_blkcnt - j,
> +				erase_buf_blks);
> +
No need for min_t() here (see above).

> +		blks_written += blk_dwrite(block_dev, blk + j,
> +				remain, erase_buffer);
> +		printf(".");
> +	}
> +
> +	return blks_written;
> +}
> +
> +static lbaint_t fb_block_write(struct blk_desc *block_dev, lbaint_t start,
> +			       lbaint_t blkcnt, const void *buffer)
> +{
> +	lbaint_t blk = start;
> +	lbaint_t blks_written = 0;
> +	lbaint_t cur_blkcnt = 0;
>
useless initialization of cur_blkcnt; definition could be moved inside
the for loop.
> +	lbaint_t blks = 0;
> +	void *erase_buf = NULL;
> +	int erase_buf_blks = 0;
> +	int step = buffer ? FASTBOOT_MAX_BLOCKS_WRITE : FASTBOOT_MAX_BLOCKS_ERASE;
> +	int i;
>
lbaint_t for 'step' an 'i' to match the type of blkcnt!

> +
> +	for (i = 0; i < blkcnt; i += step) {
> +		cur_blkcnt = min((int)blkcnt - i, step);
>
No type cast needed.


Lothar Waßmann

Re: [PATCH RFT v6 3/3] fastboot: integrate block flashing back-end

[Mattijs Korpershoek]

On Mon, Jun 30, 2025 at 17:19, Neil Armstrong <neil.armstrong@linaro.org> wrote:

> From: Dmitrii Merkurev <dimorinny@google.com>
>
> 1. Get partition info/size
> 2. Erase partition
> 3. Flash partition
> 4. BCB
>
> Make FASTBOOT_FLASH also depend on BLK, but make sure
> it doesn't affect SUNXI and ROCKCHIP platforms since they
> default to y already.
>
> Make it only default on SUNXI when MMC or NAND is enabled,
> so it doesn't break the CHIP & Ninendo boards, and for ROCKCHIP

s/Ninendo/Nintendo/ ?

I can fix when applying if needed.
Mattijs

> when MMC is enabled.
>
> Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>
> Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
> Tested-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
> ---
>  drivers/fastboot/Kconfig      | 32 ++++++++++++++++++++++++++++++--
>  drivers/fastboot/Makefile     |  1 +
>  drivers/fastboot/fb_command.c |  8 ++++++++
>  drivers/fastboot/fb_common.c  | 22 ++++++++++++++++++----
>  drivers/fastboot/fb_getvar.c  |  8 +++++++-
>  5 files changed, 64 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/fastboot/Kconfig b/drivers/fastboot/Kconfig
> index 70207573de2bd0d56b4b7fa6f7e17fdc5803ba15..b2b20a2c5e430cccc49fd6c04d6fb8825b67ec04 100644
> --- a/drivers/fastboot/Kconfig

Re: [PATCH RFT v6 1/3] fastboot: blk: introduce fastboot block flashing support

[Mattijs Korpershoek]

Hi Lothar,

Thanks for participating in review. I gave you some wording feedback
off-list but since I did not get any response I'm sending it to everyone
as well.

On Wed, Jul 02, 2025 at 04:59, Lothar Waßmann <LW@KARO-electronics.de> wrote:

> Hi,
>
> On Mon, 30 Jun 2025 17:19:57 +0200 Neil Armstrong wrote:
>> From: Dmitrii Merkurev <dimorinny@google.com>
>> 
>> Introduce fastboot block flashing functions and helpers
>> to be shared with the MMC implementation.
>> 
>> The write logic comes from the mmc implementation, while
>> the partition lookup is much simpler and could be extended.
>> 
>> For the erase logic, allmost no block drivers exposes the
>> erase operation, except mmc & virtio, so in order to allow
>> erasiong any partition a soft-erase logic has been added
>> to write zero-ed buffers in a loop.
>> 
>> Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>
>> Reviewed-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
>> Tested-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
>> ---
>>  drivers/fastboot/fb_block.c | 323 ++++++++++++++++++++++++++++++++++++++++++++
>>  include/fb_block.h          | 105 ++++++++++++++
>>  2 files changed, 428 insertions(+)
>> 
>> diff --git a/drivers/fastboot/fb_block.c b/drivers/fastboot/fb_block.c
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..b725397c91af2717812e69e2b624076eb30f781d
>> --- /dev/null
>> +++ b/drivers/fastboot/fb_block.c
>> @@ -0,0 +1,323 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * Copyright (C) 2024 The Android Open Source Project
>> + */
>> +
>> +#include <blk.h>
>> +#include <div64.h>
>> +#include <fastboot-internal.h>
>> +#include <fastboot.h>
>> +#include <fb_block.h>
>> +#include <image-sparse.h>
>> +#include <part.h>
>> +#include <malloc.h>
>>
> The alphabet seems to be a difficult concept for programmers to
> grasp... ;-)


This might be intended as a joke, but it could also be taken as an insult
for the submitter. ("the submitter is so dumb he could not even sort
alphabetically his includes").

Next time, please consider using something more neutral like:
"Make sure to sort alphabetically your includes".

No ill intention here. Thanks again for reviewing patches submitted on
the U-Boot mailing list.

Mattijs

>
>> +/**
>> + * FASTBOOT_MAX_BLOCKS_ERASE - maximum blocks to erase per derase call
>> + *
>> + * in the ERASE case we can have much larger buffer size since
>> + * we're not transferring an actual buffer
>> + */
>> +#define FASTBOOT_MAX_BLOCKS_ERASE 1048576
>> +/**
>> + * FASTBOOT_MAX_BLOCKS_SOFT_ERASE - maximum blocks to software erase at once
>> + */
>> +#define FASTBOOT_MAX_BLOCKS_SOFT_ERASE 4096
>> +/**
>> + * FASTBOOT_MAX_BLOCKS_WRITE - maximum blocks to write per dwrite call
>> + */
>> +#define FASTBOOT_MAX_BLOCKS_WRITE 65536
>> +
> Why invent an arbitrary number here, when there is already
> CONFIG_FASTBOOT_BUF_SIZE which could be used for this purpose?
>
>> +struct fb_block_sparse {
>> +	struct blk_desc	*dev_desc;
>> +};
>> +
>> +/* Write 0s instead of using erase operation, inefficient but functional */
>> +static lbaint_t fb_block_soft_erase(struct blk_desc *block_dev, lbaint_t blk,
>> +				    lbaint_t cur_blkcnt, lbaint_t erase_buf_blks,
>> +				    void *erase_buffer)
>> +{
>> +	lbaint_t blks_written = 0;
>> +	int j;
>>
> lbaint_t to match the type of cur_blkcnt and prevent integer overflow
> on 32bit systems!
>
>> +
>> +	memset(erase_buffer, 0, erase_buf_blks * block_dev->blksz);
>> +
>> +	for (j = 0; j < cur_blkcnt; j += erase_buf_blks) {
>> +		lbaint_t remain = min_t(lbaint_t, cur_blkcnt - j,
>> +				erase_buf_blks);
>> +
> No need for min_t() here (see above).
>
>> +		blks_written += blk_dwrite(block_dev, blk + j,
>> +				remain, erase_buffer);
>> +		printf(".");
>> +	}
>> +
>> +	return blks_written;
>> +}
>> +
>> +static lbaint_t fb_block_write(struct blk_desc *block_dev, lbaint_t start,
>> +			       lbaint_t blkcnt, const void *buffer)
>> +{
>> +	lbaint_t blk = start;
>> +	lbaint_t blks_written = 0;
>> +	lbaint_t cur_blkcnt = 0;
>>
> useless initialization of cur_blkcnt; definition could be moved inside
> the for loop.
>> +	lbaint_t blks = 0;
>> +	void *erase_buf = NULL;
>> +	int erase_buf_blks = 0;
>> +	int step = buffer ? FASTBOOT_MAX_BLOCKS_WRITE : FASTBOOT_MAX_BLOCKS_ERASE;
>> +	int i;
>>
> lbaint_t for 'step' an 'i' to match the type of blkcnt!
>
>> +
>> +	for (i = 0; i < blkcnt; i += step) {
>> +		cur_blkcnt = min((int)blkcnt - i, step);
>>
> No type cast needed.
>
>
> Lothar Waßmann

Re: [PATCH RFT v6 1/3] fastboot: blk: introduce fastboot block flashing support

[Neil Armstrong]

Hi,

On 02/07/2025 04:59, Lothar Waßmann wrote:
> Hi,
> 
> On Mon, 30 Jun 2025 17:19:57 +0200 Neil Armstrong wrote:
>> From: Dmitrii Merkurev <dimorinny@google.com>
>>
>> Introduce fastboot block flashing functions and helpers
>> to be shared with the MMC implementation.
>>
>> The write logic comes from the mmc implementation, while
>> the partition lookup is much simpler and could be extended.
>>
>> For the erase logic, allmost no block drivers exposes the
>> erase operation, except mmc & virtio, so in order to allow
>> erasiong any partition a soft-erase logic has been added
>> to write zero-ed buffers in a loop.
>>
>> Signed-off-by: Dmitrii Merkurev <dimorinny@google.com>
>> Reviewed-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
>> Tested-by: Mattijs Korpershoek <mkorpershoek@kernel.org>
>> Signed-off-by: Neil Armstrong <neil.armstrong@linaro.org>
>> ---
>>   drivers/fastboot/fb_block.c | 323 ++++++++++++++++++++++++++++++++++++++++++++
>>   include/fb_block.h          | 105 ++++++++++++++
>>   2 files changed, 428 insertions(+)
>>
>> diff --git a/drivers/fastboot/fb_block.c b/drivers/fastboot/fb_block.c
>> new file mode 100644
>> index 0000000000000000000000000000000000000000..b725397c91af2717812e69e2b624076eb30f781d
>> --- /dev/null
>> +++ b/drivers/fastboot/fb_block.c
>> @@ -0,0 +1,323 @@
>> +// SPDX-License-Identifier: GPL-2.0+
>> +/*
>> + * Copyright (C) 2024 The Android Open Source Project
>> + */
>> +
>> +#include <blk.h>
>> +#include <div64.h>
>> +#include <fastboot-internal.h>
>> +#include <fastboot.h>
>> +#include <fb_block.h>
>> +#include <image-sparse.h>
>> +#include <part.h>
>> +#include <malloc.h>
>>
> The alphabet seems to be a difficult concept for programmers to
> grasp... ;-)

...

> 
>> +/**
>> + * FASTBOOT_MAX_BLOCKS_ERASE - maximum blocks to erase per derase call
>> + *
>> + * in the ERASE case we can have much larger buffer size since
>> + * we're not transferring an actual buffer
>> + */
>> +#define FASTBOOT_MAX_BLOCKS_ERASE 1048576
>> +/**
>> + * FASTBOOT_MAX_BLOCKS_SOFT_ERASE - maximum blocks to software erase at once
>> + */
>> +#define FASTBOOT_MAX_BLOCKS_SOFT_ERASE 4096
>> +/**
>> + * FASTBOOT_MAX_BLOCKS_WRITE - maximum blocks to write per dwrite call
>> + */
>> +#define FASTBOOT_MAX_BLOCKS_WRITE 65536
>> +
> Why invent an arbitrary number here, when there is already
> CONFIG_FASTBOOT_BUF_SIZE which could be used for this purpose?

Those are completely different purposes, this define is related to the
image-sparse.h FASTBOOT_MAX_BLK_WRITE, but for a generic block write.

Note this is an initial implementation, any optimization could be done later.

> 
>> +struct fb_block_sparse {
>> +	struct blk_desc	*dev_desc;
>> +};
>> +
>> +/* Write 0s instead of using erase operation, inefficient but functional */
>> +static lbaint_t fb_block_soft_erase(struct blk_desc *block_dev, lbaint_t blk,
>> +				    lbaint_t cur_blkcnt, lbaint_t erase_buf_blks,
>> +				    void *erase_buffer)
>> +{
>> +	lbaint_t blks_written = 0;
>> +	int j;
>>
> lbaint_t to match the type of cur_blkcnt and prevent integer overflow
> on 32bit systems!

Ack, will fix

> 
>> +
>> +	memset(erase_buffer, 0, erase_buf_blks * block_dev->blksz);
>> +
>> +	for (j = 0; j < cur_blkcnt; j += erase_buf_blks) {
>> +		lbaint_t remain = min_t(lbaint_t, cur_blkcnt - j,
>> +				erase_buf_blks);
>> +
> No need for min_t() here (see above).

Ok

> 
>> +		blks_written += blk_dwrite(block_dev, blk + j,
>> +				remain, erase_buffer);
>> +		printf(".");
>> +	}
>> +
>> +	return blks_written;
>> +}
>> +
>> +static lbaint_t fb_block_write(struct blk_desc *block_dev, lbaint_t start,
>> +			       lbaint_t blkcnt, const void *buffer)
>> +{
>> +	lbaint_t blk = start;
>> +	lbaint_t blks_written = 0;
>> +	lbaint_t cur_blkcnt = 0;
>>
> useless initialization of cur_blkcnt; definition could be moved inside
> the for loop.

OK

>> +	lbaint_t blks = 0;
>> +	void *erase_buf = NULL;
>> +	int erase_buf_blks = 0;
>> +	int step = buffer ? FASTBOOT_MAX_BLOCKS_WRITE : FASTBOOT_MAX_BLOCKS_ERASE;
>> +	int i;
>>
> lbaint_t for 'step' an 'i' to match the type of blkcnt!

Indeed

> 
>> +
>> +	for (i = 0; i < blkcnt; i += step) {
>> +		cur_blkcnt = min((int)blkcnt - i, step);
>>
> No type cast needed.

OK will fix those.

Thank,
Neil


> 
> Lothar Waßmann