[RFC PATCH 1/7] spl: Add generic spl_load function

[Sean Anderson]

Implementers of SPL_LOAD_IMAGE_METHOD have to correctly determine what
type of image is being loaded and then call the appropriate image load
function correctly. This is tricky, because some image load functions
expect the whole image to already be loaded (CONFIG_SPL_LOAD_FIT_FULL),
some will load the image automatically using spl_load_info.read()
(CONFIG_SPL_LOAD_FIT/CONFIG_SPL_LOAD_IMX_CONTAINER), and some just parse
the header and expect the caller to do the actual loading afterwards
(legacy/raw images). Load methods often only support a subset of the
above methods, meaning that not all image types can be used with all
load methods. Further, the code to invoke these functions is
duplicated between different load functions.

To address this problem, this commit introduces a "spl_load" function.
It aims to handle image detection and correct invocation of each of the
parse/load functions. spl_simple_read is a wrapper around
spl_load_info.read with get_aligned_image* functions inlined for size
purposes. Additionally, we assume that bl_len is a power of 2 so we can
do bitshifts instead of divisions (which is smaller and faster).

Signed-off-by: Sean Anderson <sean.anderson at seco.com>
---

 common/spl/spl.c | 61 ++++++++++++++++++++++++++++++++++++++++++++++++
 include/spl.h    | 30 +++++++++++++++++++++++-
 2 files changed, 90 insertions(+), 1 deletion(-)

diff --git a/common/spl/spl.c b/common/spl/spl.c
index b452d4feeb..f26df7ac3f 100644
--- a/common/spl/spl.c
+++ b/common/spl/spl.c
@@ -398,6 +398,67 @@ int spl_parse_image_header(struct spl_image_info *spl_image,
 	return 0;
 }
 
+static int spl_simple_read(struct spl_load_info *info, void *buf, size_t size,
+			   size_t offset)
+{
+	int ret;
+	size_t bl_len = info->filename ? ARCH_DMA_MINALIGN : bl_len;
+	size_t bl_mask = bl_len - 1;
+	size_t bl_shift = ffs(bl_mask);
+	size_t overhead = offset & bl_mask;
+
+	buf -= overhead;
+	size = (size + overhead + bl_mask) >> bl_shift;
+	offset = offset >> bl_shift;
+
+	ret = info->read(info, offset, size, buf);
+	return ret == size ? 0 : -EIO;
+}
+
+int spl_load(struct spl_image_info *spl_image,
+	     const struct spl_boot_device *bootdev, struct spl_load_info *info,
+	     struct image_header *header, size_t size, size_t sector)
+{
+	int ret;
+	size_t offset = sector * info->bl_len;
+
+	if (image_get_magic(header) == FDT_MAGIC) {
+		if (IS_ENABLED(CONFIG_SPL_LOAD_FIT_FULL)) {
+			void *buf;
+
+			/*
+			 * In order to support verifying images in the FIT, we
+			 * need to load the whole FIT into memory. Try and
+			 * guess how much we need to load by using the total
+			 * size. This will fail for FITs with external data,
+			 * but there's not much we can do about that.
+			 */
+			if (!size)
+				size = roundup(fdt_totalsize(header), 4);
+			buf = spl_get_load_buffer(0, size);
+			ret = spl_simple_read(info, buf, size, offset);
+			if (ret)
+				return ret;
+
+			return spl_parse_image_header(spl_image, bootdev, buf);
+		}
+
+		if (IS_ENABLED(CONFIG_SPL_LOAD_FIT))
+			return spl_load_simple_fit(spl_image, info, sector,
+						   header);
+	}
+
+	if (IS_ENABLED(CONFIG_SPL_LOAD_IMX_CONTAINER))
+		return spl_load_imx_container(spl_image, info, sector);
+
+	ret = spl_parse_image_header(spl_image, bootdev, header);
+	if (ret)
+		return ret;
+
+	return spl_simple_read(info, (void *)spl_image->load_addr,
+			       spl_image->size, offset + spl_image->offset);
+}
+
 __weak void __noreturn jump_to_image_no_args(struct spl_image_info *spl_image)
 {
 	typedef void __noreturn (*image_entry_noargs_t)(void);
diff --git a/include/spl.h b/include/spl.h
index 8ceb3c0f09..6606f4e5f6 100644
--- a/include/spl.h
+++ b/include/spl.h
@@ -236,7 +236,7 @@ struct spl_image_info {
  *
  * @dev: Pointer to the device, e.g. struct mmc *
  * @priv: Private data for the device
- * @bl_len: Block length for reading in bytes
+ * @bl_len: Block length for reading in bytes; must be a power of 2
  * @filename: Name of the fit image file.
  * @read: Function to call to read from the device
  */
@@ -608,6 +608,34 @@ int spl_load_image_ext_os(struct spl_image_info *spl_image,
 			  struct spl_boot_device *bootdev,
 			  struct blk_desc *block_dev, int partition);
 
+/**
+ * spl_load() - Parse a header and load the image
+ * @spl_image: Image data which will be filled in by this function
+ * @bootdev: The device to load from
+ * @info: Describes how to load additional information from @bootdev. At the
+ *        minimum, read() and bl_len must be populated.
+ * @header: The image header. This should already have been loaded. It may be
+ *          clobbered by the load process (if e.g. the load address overlaps).
+ * @size: The size of the image, if it is known in advance. Some boot devices
+ *        (such as filesystems) know how big an image is before parsing the
+ *        header. If this information is unknown, then the size will be
+ *        determined from the header.
+ * @sectors: The offset from the start if @bootdev, in units of @info->bl_len.
+ *           This should have the offset @header was loaded from. It will be
+ *           added to any offsets passed to @info->read().
+ *
+ * This function determines the image type (FIT, legacy, i.MX, raw, etc), calls
+ * the appropriate parsing function, determines the load address, and the loads
+ * the image from storage. It is designed to replace ad-hoc image loading which
+ * may not support all image types (especially when config options are
+ * involved).
+ *
+ * Return: 0 on success, or a negative error on failure
+ */
+int spl_load(struct spl_image_info *spl_image,
+	     const struct spl_boot_device *bootdev, struct spl_load_info *info,
+	     struct image_header *header, size_t size, size_t sector);
+
 /**
  * spl_early_init() - Set up device tree and driver model in SPL if enabled
  *
-- 
2.35.1.1320.gc452695387.dirty