ppc: bootm: relocate fdt to valid boot memory

For the MPC85xx family of SOCs Linux expects any boot firmware
information to be passed in the first 64MiB of memory. This adds support
to ensure that the device tree is relocated to a valid location if it is
outside that address range.

For the other SOC family currently present in the ppc architecture, the
default is not to relocate as at Linux startup the virtual address
equals the physical address.

Signed-off-by: Renaud Barbier <renaud.barbier@ge.com>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 48 insertions, 1 deletions

diff --git a/arch/ppc/lib/ppclinux.c b/arch/ppc/lib/ppclinux.c
index ef69eadfb7..7c30ac3386 100644
--- a/arch/ppc/lib/ppclinux.c
+++ b/arch/ppc/lib/ppclinux.c
@@ -4,12 +4,45 @@
 #include <command.h>
 #include <image.h>
 #include <init.h>
+#include <malloc.h>
 #include <environment.h>
 #include <asm/bitops.h>
+#include <asm/processor.h>
 #include <boot.h>
 #include <errno.h>
 #include <fs.h>
 
+static int bootm_relocate_fdt(void *addr, struct image_data *data)
+{
+	if (addr < LINUX_TLB1_MAX_ADDR) {
+		/* The kernel is within  the boot TLB mapping.
+		 * Put the DTB above if there is no space
+		 * below.
+		 */
+		if (addr < (void *)data->oftree->totalsize) {
+			addr = (void *)PAGE_ALIGN((phys_addr_t)addr +
+					data->os->header.ih_size);
+			addr += data->oftree->totalsize;
+			if (addr < LINUX_TLB1_MAX_ADDR)
+				addr = LINUX_TLB1_MAX_ADDR;
+		}
+	}
+
+	if (addr > LINUX_TLB1_MAX_ADDR) {
+		pr_crit("Unable to relocate DTB to Linux TLB\n");
+		return 1;
+	}
+
+	addr = (void *)PAGE_ALIGN_DOWN((phys_addr_t)addr -
+			data->oftree->totalsize);
+	memcpy(addr, data->oftree, data->oftree->totalsize);
+	free(data->oftree);
+	data->oftree = addr;
+
+	pr_info("Relocating device tree to 0x%p\n", addr);
+	return 0;
+}
+
 static int do_bootm_linux(struct image_data *data)
 {
 	void	(*kernel)(void *, void *, unsigned long,
@@ -24,6 +57,20 @@ static int do_bootm_linux(struct image_data *data)
 		return -EINVAL;
 	}
 
+	/* Relocate the device tree if outside the initial
+	 * Linux mapped TLB.
+	 */
+	if (IS_ENABLED(CONFIG_MPC85xx)) {
+		void *addr = data->oftree;
+
+		if ((addr + data->oftree->totalsize) > LINUX_TLB1_MAX_ADDR) {
+			addr = (void *)data->os_address;
+
+			if (bootm_relocate_fdt(addr, data))
+				goto error;
+		}
+	}
+
 	fdt_add_reserve_map(data->oftree);
 
 	kernel = (void *)(data->os_address + data->os_entry);
@@ -40,7 +87,7 @@ static int do_bootm_linux(struct image_data *data)
 
 	reset_cpu(0);
 
-	/* not reached */
+error:
 	return -1;
 }