[RFC] xload: get barebox size from barebox_arm_head

[Jan Weitzel]

Add functions to read the barebox_arm_head, check barebox magicword
and read out the barebox image size.
Create a inital partion of 1Mb to access the barebox image on nand.
Fall back to 512 Byte.

Where is a good place for the helper functions? arch/arm/lib ?

Signed-off-by: Jan Weitzel <j.weitzel at phytec.de>
---
 arch/arm/include/asm/barebox-arm-head.h |    4 ++
 arch/arm/mach-omap/include/mach/xload.h |    2 +-
 arch/arm/mach-omap/xload.c              |   55 ++++++++++++++++++++++++++++--
 3 files changed, 56 insertions(+), 5 deletions(-)

diff --git a/arch/arm/include/asm/barebox-arm-head.h b/arch/arm/include/asm/barebox-arm-head.h
index 0dc3074..521bcf6 100644
--- a/arch/arm/include/asm/barebox-arm-head.h
+++ b/arch/arm/include/asm/barebox-arm-head.h
@@ -1,6 +1,10 @@
 #ifndef __ASM_ARM_HEAD_H
 #define __ASM_ARM_HEAD_H
 
+#define ARM_HEAD_SIZE		0x30
+#define HEAD_MAGICWORD_OFFSET	0x20
+#define HEAD_SIZE_OFFSET	0x2C
+
 static inline void barebox_arm_head(void)
 {
 	__asm__ __volatile__ (
diff --git a/arch/arm/mach-omap/include/mach/xload.h b/arch/arm/mach-omap/include/mach/xload.h
index 844b57f..26f1b68 100644
--- a/arch/arm/mach-omap/include/mach/xload.h
+++ b/arch/arm/mach-omap/include/mach/xload.h
@@ -1,7 +1,7 @@
 #ifndef _MACH_XLOAD_H
 #define _MACH_XLOAD_H
 
-void *omap_xload_boot_nand(int offset, int size);
+void *omap_xload_boot_nand(int offset);
 void *omap_xload_boot_mmc(void);
 
 enum omap_boot_src {
diff --git a/arch/arm/mach-omap/xload.c b/arch/arm/mach-omap/xload.c
index 9a6b0b4..eff2ea0 100644
--- a/arch/arm/mach-omap/xload.c
+++ b/arch/arm/mach-omap/xload.c
@@ -7,16 +7,63 @@
 #include <fcntl.h>
 #include <mach/xload.h>
 #include <sizes.h>
+#include <asm/barebox-arm-head.h>
 
-void *omap_xload_boot_nand(int offset, int size)
+void *read_image_head(const char *name)
+{
+	void *header = xmalloc(ARM_HEAD_SIZE);
+	struct cdev *cdev;
+	int ret;
+
+	cdev = cdev_open(name, O_RDONLY);
+	if (!cdev) {
+		printf("failed to open partition\n");
+		return NULL;
+	}
+
+	ret = cdev_read(cdev, header, ARM_HEAD_SIZE, 0, 0);
+	cdev_close(cdev);
+
+	if (ret != ARM_HEAD_SIZE) {
+		printf("failed to read from partition\n");
+		return NULL;
+	}
+
+	return header;
+}
+
+unsigned int get_image_size(void *head)
+{
+	unsigned int ret = 0;
+	unsigned int *psize = head + HEAD_SIZE_OFFSET;
+	const char *pmagic = head + HEAD_MAGICWORD_OFFSET;
+
+	if (!head)
+		return 0;
+
+	if (!strcmp(pmagic, "barebox"))
+		ret = *psize;
+	debug("Detected barebox image size %u\n", ret);
+
+	return ret;
+}
+
+void *omap_xload_boot_nand(int offset)
 {
 	int ret;
-	void *to = xmalloc(size);
+	int size;
+	void *to;
 	struct cdev *cdev;
 
-	devfs_add_partition("nand0", offset, size, PARTITION_FIXED, "x");
+	devfs_add_partition("nand0", offset, SZ_1M, PARTITION_FIXED, "x");
 	dev_add_bb_dev("x", "bbx");
 
+	size = get_image_size(read_image_head("bbx"));
+	if (!size)
+		size = SZ_512K;
+
+	to = xmalloc(size);
+
 	cdev = cdev_open("bbx", O_RDONLY);
 	if (!cdev) {
 		printf("failed to open nand\n");
@@ -80,7 +127,7 @@ int run_shell(void)
 		printf("unknown boot source. Fall back to nand\n");
 	case OMAP_BOOTSRC_NAND:
 		printf("booting from NAND\n");
-		func = omap_xload_boot_nand(SZ_128K, SZ_512K);
+		func = omap_xload_boot_nand(SZ_128K);
 		break;
 	}
 
-- 
1.7.0.4