blkmap: pass information on ISO image to the OS

The EFI HTTP boot puts the ISO installer image at some location in
memory. Information about this image has to be passed on to the OS
kernel, which is done by adding a persistent memory(pmem) node to the
devicetree(DT) that is passed to the OS. The OS kernel then gets
information about the presence of this ISO image and proceeds with the
installation.

In U-Boot, this ISO image gets mounted as a memory mapped blkmap
device slice, with the 'preserve' attribute. Add a helper function
which iterates through all such slices, and invokes a callback. The
callback adds the pmem node to the DT and removes the corresponding
memory region from the EFI memory map. Invoke this helper function as
part of the DT fixup which happens before booting the OS.

Signed-off-by: Sughosh Ganu <[email protected]>
Reviewed-by: Tobias Waldekranz <[email protected]>
Signed-off-by: Ilias Apalodimas <[email protected]>

1 files changed, 42 insertions, 0 deletions

diff --git a/lib/efi_loader/efi_helper.c b/lib/efi_loader/efi_helper.c
index f6fbcdffe82..8c32059edda 100644
--- a/lib/efi_loader/efi_helper.c
+++ b/lib/efi_loader/efi_helper.c
@@ -5,6 +5,7 @@
 
 #define LOG_CATEGORY LOGC_EFI
 
+#include <blkmap.h>
 #include <bootm.h>
 #include <env.h>
 #include <image.h>
@@ -687,3 +688,44 @@ out:
 
 	return ret;
 }
+
+/**
+ * pmem_node_efi_memmap_setup() - Add pmem node and tweak EFI memmap
+ * @fdt: The devicetree to which pmem node is added
+ * @addr: start address of the pmem node
+ * @size: size of the memory of the pmem node
+ *
+ * The function adds the pmem node to the device-tree along with removing
+ * the corresponding region from the EFI memory map. Used primarily to
+ * pass the information of a RAM based ISO image to the OS.
+ *
+ * Return: 0 on success, -ve value on error
+ */
+static int pmem_node_efi_memmap_setup(void *fdt, u64 addr, u64 size)
+{
+	int ret;
+	u64 pages;
+	efi_status_t status;
+
+	ret = fdt_fixup_pmem_region(fdt, addr, size);
+	if (ret) {
+		log_err("Failed to setup pmem node for addr %#llx, size %#llx, err %d\n",
+			addr, size, ret);
+		return ret;
+	}
+
+	/* Remove the pmem region from the EFI memory map */
+	pages = efi_size_in_pages(size + (addr & EFI_PAGE_MASK));
+	status = efi_update_memory_map(addr, pages, EFI_CONVENTIONAL_MEMORY,
+				       false, true);
+	if (status != EFI_SUCCESS)
+		return -1;
+
+	return 0;
+}
+
+int fdt_efi_pmem_setup(void *fdt)
+{
+	return blkmap_get_preserved_pmem_slices(pmem_node_efi_memmap_setup,
+						fdt);
+}