spl: blk: Support loading images from fs

Add a generic API to support loading of SPL payload from any supported
filesystem on a given partition of a block device.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
diff --git a/common/spl/spl_blk_fs.c b/common/spl/spl_blk_fs.c
new file mode 100644
index 0000000..d97adc4
--- /dev/null
+++ b/common/spl/spl_blk_fs.c
@@ -0,0 +1,134 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2023
+ * Ventana Micro Systems Inc.
+ *
+ */
+
+#include <common.h>
+#include <spl.h>
+#include <image.h>
+#include <fs.h>
+
+struct blk_dev {
+	const char *ifname;
+	char dev_part_str[8];
+};
+
+static ulong spl_fit_read(struct spl_load_info *load, ulong file_offset,
+			  ulong size, void *buf)
+{
+	loff_t actlen;
+	int ret;
+	struct blk_dev *dev = (struct blk_dev *)load->priv;
+
+	ret = fs_set_blk_dev(dev->ifname, dev->dev_part_str, FS_TYPE_ANY);
+	if (ret) {
+		printf("spl: unable to set blk_dev %s %s. Err - %d\n",
+		       dev->ifname, dev->dev_part_str, ret);
+		return ret;
+	}
+
+	ret = fs_read(load->filename, (ulong)buf, file_offset, size, &actlen);
+	if (ret < 0) {
+		printf("spl: error reading image %s. Err - %d\n",
+		       load->filename, ret);
+		return ret;
+	}
+
+	return actlen;
+}
+
+int spl_blk_load_image(struct spl_image_info *spl_image,
+		       struct spl_boot_device *bootdev,
+		       enum uclass_id uclass_id, int devnum, int partnum)
+{
+	const char *filename = CONFIG_SPL_PAYLOAD;
+	struct disk_partition part_info = {};
+	struct legacy_img_hdr *header;
+	struct blk_desc *blk_desc;
+	loff_t actlen, filesize;
+	struct blk_dev dev;
+	int ret;
+
+	blk_desc = blk_get_devnum_by_uclass_id(uclass_id, devnum);
+	if (!blk_desc) {
+		printf("blk desc for %d %d not found\n", uclass_id, devnum);
+		goto out;
+	}
+
+	blk_show_device(uclass_id, devnum);
+	header = spl_get_load_buffer(-sizeof(*header), sizeof(*header));
+	ret = part_get_info(blk_desc, 1, &part_info);
+	if (ret) {
+		printf("spl: no partition table found. Err - %d\n", ret);
+		goto out;
+	}
+
+	dev.ifname = blk_get_uclass_name(uclass_id);
+	snprintf(dev.dev_part_str, sizeof(dev.dev_part_str) - 1, "%d:%d",
+		 devnum, partnum);
+	ret = fs_set_blk_dev(dev.ifname, dev.dev_part_str, FS_TYPE_ANY);
+	if (ret) {
+		printf("spl: unable to set blk_dev %s %s. Err - %d\n",
+		       dev.ifname, dev.dev_part_str, ret);
+		goto out;
+	}
+
+	ret = fs_read(filename, (ulong)header, 0,
+		      sizeof(struct legacy_img_hdr), &actlen);
+	if (ret) {
+		printf("spl: unable to read file %s. Err - %d\n", filename,
+		       ret);
+		goto out;
+	}
+
+	if (IS_ENABLED(CONFIG_SPL_LOAD_FIT) &&
+	    image_get_magic(header) == FDT_MAGIC) {
+		struct spl_load_info load;
+
+		debug("Found FIT\n");
+		load.read = spl_fit_read;
+		load.bl_len = 1;
+		load.filename = (void *)filename;
+		load.priv = &dev;
+
+		return spl_load_simple_fit(spl_image, &load, 0, header);
+	}
+
+	ret = spl_parse_image_header(spl_image, bootdev, header);
+	if (ret) {
+		printf("spl: unable to parse image header. Err - %d\n",
+		       ret);
+		goto out;
+	}
+
+	ret = fs_set_blk_dev(dev.ifname, dev.dev_part_str, FS_TYPE_ANY);
+	if (ret) {
+		printf("spl: unable to set blk_dev %s %s. Err - %d\n",
+		       dev.ifname, dev.dev_part_str, ret);
+		goto out;
+	}
+
+	ret = fs_size(filename, &filesize);
+	if (ret) {
+		printf("spl: unable to get file size: %s. Err - %d\n",
+		       filename, ret);
+		goto out;
+	}
+
+	ret = fs_set_blk_dev(dev.ifname, dev.dev_part_str, FS_TYPE_ANY);
+	if (ret) {
+		printf("spl: unable to set blk_dev %s %s. Err - %d\n",
+		       dev.ifname, dev.dev_part_str, ret);
+		goto out;
+	}
+
+	ret = fs_read(filename, (ulong)spl_image->load_addr, 0, filesize,
+		      &actlen);
+	if (ret)
+		printf("spl: unable to read file %s. Err - %d\n",
+		       filename, ret);
+out:
+	return ret;
+}