sunxi: Normalise FEL support

Make sunxi's FEL code fit with the normal U-Boot boot sequence instead of
creating its own. There are some #ifdefs required in start.S. Future work
will hopefully remove these.

This series is available at u-boot-dm, branch sunxi-working.

Signed-off-by: Simon Glass <sjg@chromium.org>
Acked-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>

arch/arm/cpu/armv7/start.S

@@ -54,7 +54,8 @@ save_boot_params_ret:
  * (OMAP4 spl TEXT_BASE is not 32 byte aligned.
  * Continue to use ROM code vector only in OMAP4 spl)
  */
-#if !(defined(CONFIG_OMAP44XX) && defined(CONFIG_SPL_BUILD))
+#if !(defined(CONFIG_OMAP44XX) && defined(CONFIG_SPL_BUILD)) && \
+		!defined(CONFIG_SPL_FEL)
 	/* Set V=0 in CP15 SCTLR register - for VBAR to point to vector */
 	mrc	p15, 0, r0, c1, c0, 0	@ Read CP15 SCTLR Register
 	bic	r0, #CR_V		@ V = 0
@@ -67,7 +68,9 @@ save_boot_params_ret:
 
 	/* the mask ROM code should have PLL and others stable */
 #ifndef CONFIG_SKIP_LOWLEVEL_INIT
+#ifndef CONFIG_SPL_FEL
 	bl	cpu_init_cp15
+#endif
 	bl	cpu_init_crit
 #endif
 

arch/arm/cpu/armv7/sunxi/Makefile

@@ -39,7 +39,5 @@ obj-$(CONFIG_MACH_SUN5I)	+= dram_sun4i.o
 obj-$(CONFIG_MACH_SUN6I)	+= dram_sun6i.o
 obj-$(CONFIG_MACH_SUN7I)	+= dram_sun4i.o
 obj-$(CONFIG_MACH_SUN8I)	+= dram_sun8i.o
-ifdef CONFIG_SPL_FEL
-obj-y	+= start.o
-endif
+obj-y	+= fel_utils.o
 endif

arch/arm/cpu/armv7/sunxi/board.c

@@ -27,6 +27,13 @@
 
 #include <linux/compiler.h>
 
+struct fel_stash {
+	uint32_t sp;
+	uint32_t lr;
+};
+
+struct fel_stash fel_stash __attribute__((section(".data")));
+
 static int gpio_init(void)
 {
 #if CONFIG_CONS_INDEX == 1 && defined(CONFIG_UART0_PORT_F)
@@ -65,6 +72,12 @@ static int gpio_init(void)
 	return 0;
 }
 
+void spl_board_load_image(void)
+{
+	debug("Returning to FEL sp=%x, lr=%x\n", fel_stash.sp, fel_stash.lr);
+	return_to_fel(fel_stash.sp, fel_stash.lr);
+}
+
 void s_init(void)
 {
 #if defined CONFIG_MACH_SUN6I || defined CONFIG_MACH_SUN8I
@@ -95,6 +108,14 @@ void s_init(void)
  */
 u32 spl_boot_device(void)
 {
+	/*
+	 * Have we been asked to return to the FEL portion of the boot ROM?
+	 * TODO: We need a more robust test here, or bracket this with
+	 * #ifdef CONFIG_SPL_FEL.
+	 */
+	if (fel_stash.lr >= 0xffff0000 && fel_stash.lr < 0xffff4000)
+		return BOOT_DEVICE_BOARD;
+
 	return BOOT_DEVICE_MMC1;
 }
 

arch/arm/cpu/armv7/sunxi/config.mk

@@ -1,8 +1,6 @@
 # Build a combined spl + u-boot image
 ifdef CONFIG_SPL
 ifndef CONFIG_SPL_BUILD
-ifndef CONFIG_SPL_FEL
 ALL-y += u-boot-sunxi-with-spl.bin
 endif
 endif
-endif

arch/arm/cpu/armv7/sunxi/fel_utils.S

@@ -0,0 +1,25 @@
+/*
+ * Utility functions for FEL mode.
+ *
+ * Copyright (c) 2015 Google, Inc
+ *
+ * SPDX-License-Identifier:	GPL-2.0+
+ */
+
+#include <asm-offsets.h>
+#include <config.h>
+#include <asm/system.h>
+#include <linux/linkage.h>
+
+ENTRY(save_boot_params)
+	ldr	r0, =fel_stash
+	str	sp, [r0, #0]
+	str	lr, [r0, #4]
+	b	save_boot_params_ret
+ENDPROC(save_boot_params)
+
+ENTRY(return_to_fel)
+	mov	sp, r0
+	mov	lr, r1
+	bx	lr
+ENDPROC(return_to_fel)

arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds

@@ -1,82 +0,0 @@
-/*
- * (C) Copyright 2013
- * Henrik Nordstrom <henrik@henriknordstrom.net>
- *
- * SPDX-License-Identifier:	GPL-2.0+
- */
-OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm")
-OUTPUT_ARCH(arm)
-ENTRY(s_init)
-SECTIONS
-{
-	. = 0x00002000;
-
-	. = ALIGN(4);
-	.text :
-	{
-		*(.text.s_init)
-		*(.text*)
-	}
-
-	. = ALIGN(4);
-	.rodata : { *(SORT_BY_ALIGNMENT(SORT_BY_NAME(.rodata*))) }
-
-	. = ALIGN(4);
-	.data : {
-		*(.data*)
-	}
-
-	. = ALIGN(4);
-	.u_boot_list : {
-		KEEP(*(SORT(.u_boot_list*)));
-	}
-
-	. = ALIGN(4);
-	. = .;
-
-	. = ALIGN(4);
-	.rel.dyn : {
-		__rel_dyn_start = .;
-		*(.rel*)
-		__rel_dyn_end = .;
-	}
-
-	.dynsym : {
-		__dynsym_start = .;
-		*(.dynsym)
-	}
-
-	. = ALIGN(4);
-	.note.gnu.build-id :
-	{
-		*(.note.gnu.build-id)
-	}
-	_end = .;
-
-	. = ALIGN(4096);
-	.mmutable : {
-		*(.mmutable)
-	}
-
-	.bss_start __rel_dyn_start (OVERLAY) : {
-		KEEP(*(.__bss_start));
-		__bss_base = .;
-	}
-
-	.bss __bss_base (OVERLAY) : {
-		*(.bss*)
-		. = ALIGN(4);
-		__bss_limit = .;
-	}
-
-	.bss_end __bss_limit (OVERLAY) : {
-		KEEP(*(.__bss_end));
-	}
-
-	/DISCARD/ : { *(.dynstr*) }
-	/DISCARD/ : { *(.dynamic*) }
-	/DISCARD/ : { *(.plt*) }
-	/DISCARD/ : { *(.interp*) }
-	/DISCARD/ : { *(.gnu*) }
-	/DISCARD/ : { *(.note*) }
-}

arch/arm/include/asm/arch-sunxi/sys_proto.h

@@ -13,4 +13,14 @@
 
 void sdelay(unsigned long);
 
+/* return_to_fel() - Return to BROM from SPL
+ *
+ * This returns back into the BROM after U-Boot SPL has performed its initial
+ * init. It uses the provided lr and sp to do so.
+ *
+ * @lr:		BROM link register value (return address)
+ * @sp:		BROM stack pointer
+ */
+void return_to_fel(uint32_t lr, uint32_t sp);
+
 #endif

board/sunxi/Kconfig

@@ -149,6 +149,16 @@ config SPL_FEL
 	bool "SPL/FEL mode support"
 	depends on SPL
 	default n
+	help
+	  This enables support for Fast Early Loader (FEL) mode. This
+	  allows U-Boot to be loaded to the board over USB by the on-chip
+	  boot rom. U-Boot should be sent in two parts: SPL first, with
+	  'fel write 0x2000 u-boot-spl.bin; fel exe 0x2000' then U-Boot with
+	  'fel write 0x4a000000 u-boot.bin; fel exe 0x4a000000'. This option
+	  shrinks the amount of SRAM available to SPL, so only enable it if
+	  you need FEL. Note that enabling this option only allows FEL to be
+	  used; it is still possible to boot U-Boot from boot media. U-Boot
+	  SPL detects when it is being loaded using FEL.
 
 config UART0_PORT_F
 	bool "UART0 on MicroSD breakout board"

include/configs/sunxi-common.h

@@ -18,10 +18,8 @@
  */
 #define CONFIG_SUNXI		/* sunxi family */
 #ifdef CONFIG_SPL_BUILD
-#ifndef CONFIG_SPL_FEL
 #define CONFIG_SYS_THUMB_BUILD	/* Thumbs mode to save space in SPL */
 #endif
-#endif
 
 #include <asm/arch/cpu.h>	/* get chip and board defs */
 
@@ -149,10 +147,10 @@
 #define CONFIG_SPL_SERIAL_SUPPORT
 #define CONFIG_SPL_LIBGENERIC_SUPPORT
 
+#define CONFIG_SPL_BOARD_LOAD_IMAGE
+
 #ifdef CONFIG_SPL_FEL
 
-#define CONFIG_SPL_LDSCRIPT "arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds"
-#define CONFIG_SPL_START_S_PATH "arch/arm/cpu/armv7/sunxi"
 #define CONFIG_SPL_TEXT_BASE		0x2000
 #define CONFIG_SPL_MAX_SIZE		0x4000		/* 16 KiB */
 

scripts/Makefile.spl

@@ -154,10 +154,8 @@ ALL-y	+= $(obj)/$(BOARD)-spl.bin
 endif
 
 ifdef CONFIG_SUNXI
-ifndef CONFIG_SPL_FEL
 ALL-y	+= $(obj)/sunxi-spl.bin
 endif
-endif
 
 ifeq ($(CONFIG_SYS_SOC),"at91")
 ALL-y	+= boot.bin