mmc: fsl_esdhc_spl: Add support for builds without CONFIG_SYS_MMC_U_BOOT_OFFS

When fixed offset via CONFIG_SYS_MMC_U_BOOT_OFFS is not specified then
expects that U-Boot proper is placed immediately after SPL without any
additional padding.

This allows to generate smaller SPL+U-Boot final binary as it is not
required to specify fixed offset to U-Boot proper at SPL compile time.

In this case offset to U-Boot proper is calculated at SPL compile time in
linker script.

Signed-off-by: Pali Rohár <pali@kernel.org>
Reviewed-by: Jaehoon Chung <jh80.chung@samsung.com>
Signed-off-by: Marek Behún <kabel@kernel.org>
diff --git a/arch/powerpc/cpu/mpc85xx/u-boot-spl.lds b/arch/powerpc/cpu/mpc85xx/u-boot-spl.lds
index 89df4b5..a36aa17 100644
--- a/arch/powerpc/cpu/mpc85xx/u-boot-spl.lds
+++ b/arch/powerpc/cpu/mpc85xx/u-boot-spl.lds
@@ -62,6 +62,13 @@
 	__init_begin = .;
 	__init_end = .;
 	_end = .;
+
+#ifndef KEEP_RESET_VECTOR
+#if defined(CONFIG_SD_BOOT) && !defined(CONFIG_SYS_MMC_U_BOOT_OFFS)
+	mmc_u_boot_offs = .;
+#endif
+#endif
+
 #ifdef CONFIG_SPL_SKIP_RELOCATE
 	. = ALIGN(4);
 	__bss_start = .;
@@ -94,6 +101,9 @@
 	.resetvec IMAGE_TEXT_BASE + RESET_VECTOR_OFFSET : {
 		KEEP(*(.resetvec))
 	} = 0xffff
+#if defined(CONFIG_SD_BOOT) && !defined(CONFIG_SYS_MMC_U_BOOT_OFFS)
+	mmc_u_boot_offs = .;
+#endif
 #endif
 
 #ifndef CONFIG_SPL_SKIP_RELOCATE
diff --git a/drivers/mmc/fsl_esdhc_spl.c b/drivers/mmc/fsl_esdhc_spl.c
index dd6d5fa..aa00d7e 100644
--- a/drivers/mmc/fsl_esdhc_spl.c
+++ b/drivers/mmc/fsl_esdhc_spl.c
@@ -9,6 +9,10 @@
 #include <mmc.h>
 #include <malloc.h>
 
+#ifndef CONFIG_SYS_MMC_U_BOOT_OFFS
+extern uchar mmc_u_boot_offs[];
+#endif
+
 /*
  * The environment variables are written to just after the u-boot image
  * on SDCard, so we must read the MBR to get the start address and code
@@ -149,8 +153,12 @@
 		val = *(tmp_buf + blk_off + ESDHC_BOOT_IMAGE_ADDR + i);
 		offset = (offset << 8) + val;
 	}
+#ifndef CONFIG_SYS_MMC_U_BOOT_OFFS
+	offset += (ulong)&mmc_u_boot_offs - CONFIG_SPL_TEXT_BASE;
+#else
 	offset += CONFIG_SYS_MMC_U_BOOT_OFFS;
 #endif
+#endif
 	/*
 	* Load U-Boot image from mmc into RAM
 	*/