Re: [U-Boot] [PATCH v2 3/3] sunxi: Normalise FEL support

On Sat, 7 Feb 2015 10:47:30 -0700 Simon Glass sjg@chromium.org wrote:

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

Changes in v2:

• Adjust for new save_boot_params() API
• Drop patch to change r0 to r2 in start.S
• Add #ifdefs to start.S to deal with FEL
• Use 'Fast Early Loader' as the full name for FEL

Thanks for working on these patches. It looks like we are finally getting really close to resolving the sunxi FEL boot problem.

Some comments are below.

arch/arm/cpu/armv7/start.S | 5 +- arch/arm/cpu/armv7/sunxi/Makefile | 4 +- arch/arm/cpu/armv7/sunxi/board.c | 21 ++++++++ arch/arm/cpu/armv7/sunxi/config.mk | 2 - arch/arm/cpu/armv7/sunxi/fel_utils.S | 25 +++++++++ arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds | 82 ----------------------------- arch/arm/include/asm/arch-sunxi/sys_proto.h | 10 ++++ board/sunxi/Kconfig | 10 ++++ include/configs/sunxi-common.h | 6 +-- scripts/Makefile.spl | 2 - 10 files changed, 73 insertions(+), 94 deletions(-) create mode 100644 arch/arm/cpu/armv7/sunxi/fel_utils.S delete mode 100644 arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds

diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S index 9b49ece..098a83a 100644 --- a/arch/arm/cpu/armv7/start.S +++ b/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)
  

Maybe we can just update the 'save_boot_params' function to save the important configuration registers and then undo this configuration in 'return_to_fel'? This allows us to avoid the sunxi specific ifdefs in the core ARM code.

In this particular case, restoring VBAR and CPSR is important because the BROM code uses an IRQ handler for FEL (presumably USB related). And we want to ensure that this IRQ handler works properly again after resuming the FEL code.

/* 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

Same here.

bl cpu_init_cp15 +#endif bl cpu_init_crit #endif

diff --git a/arch/arm/cpu/armv7/sunxi/Makefile b/arch/arm/cpu/armv7/sunxi/Makefile index 48db744..c1b975a 100644 --- a/arch/arm/cpu/armv7/sunxi/Makefile +++ b/arch/arm/cpu/armv7/sunxi/Makefile @@ -38,7 +38,5 @@ 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 diff --git a/arch/arm/cpu/armv7/sunxi/board.c b/arch/arm/cpu/armv7/sunxi/board.c index 6e28bcd..b7492ac 100644 --- a/arch/arm/cpu/armv7/sunxi/board.c +++ b/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 { uint32_t sp; uint32_t lr; uint32_t cpsr; uint32_t sctlr; uint32_t vbar; uint32_t cr; };

+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;

It is probably better to do it this way:

#ifdef CONFIG_SPL_FEL return BOOT_DEVICE_BOARD; #else if (memcmp((void *)4, "eGON.BT0", 8) == 0) return BOOT_DEVICE_MMC1; else return BOOT_DEVICE_BOARD; #endif

The memcmp (or equivalent code) ensures that it is compatible with https://github.com/ssvb/sunxi-tools/commit/aa7e1880986e5c9a825b08aed9dc5621b...

Then the new 'fel spl u-boot-sunxi-with-spl.bin' command for loading and executing the SPL works fine without CONFIG_SPL_FEL defined (because the SD card specific "eGON.BT0" signature is replaced with the "eGON.FEL" signature by the 'fel' tool in the device memory before transferring control to the SPL code). Needless to say that the SPL built this way still works when written to the SD card.

And if CONFIG_SPL_FEL is defined, then the FEL support still works in a legacy way (via 'fel write 0x2000 u-boot-spl.bin; fel exe 0x2000').

We would only need to drop the legacy way in u-boot v2015.07 if the new one proves to be problem free by that time :-)

}

diff --git a/arch/arm/cpu/armv7/sunxi/config.mk b/arch/arm/cpu/armv7/sunxi/config.mk index 00f5ffc..76ffec9 100644 --- a/arch/arm/cpu/armv7/sunxi/config.mk +++ b/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 diff --git a/arch/arm/cpu/armv7/sunxi/fel_utils.S b/arch/arm/cpu/armv7/sunxi/fel_utils.S new file mode 100644 index 0000000..0c1de52 --- /dev/null +++ b/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)

ENTRY(save_boot_params) ldr r0, =fel_stash str sp, [r0, #0] str lr, [r0, #4] mrs lr, cpsr @ Read CPSR str lr, [r0, #8] mrc p15, 0, lr, c1, c0, 0 @ Read CP15 SCTLR str lr, [r0, #12] mrc p15, 0, lr, c12, c0, 0 @ Read VBAR str lr, [r0, #16] mrc p15, 0, lr, c1, c0, 0 @ Read CP15 Control str lr, [r0, #20] b save_boot_params_ret ENDPROC(save_boot_params)

ENTRY(return_to_fel) ldr r0, =fel_stash ldr lr, [r0, #20] mcr p15, 0, lr, c1, c0, 0 @ Write CP15 Control ldr lr, [r0, #16] mcr p15, 0, lr, c12, c0, 0 @ Write VBAR ldr lr, [r0, #12] mcr p15, 0, lr, c1, c0, 0 @ Write CP15 SCTLR ldr lr, [r0, #8] msr cpsr, lr @ Write CPSR ldr sp, [r0, #0] ldr lr, [r0, #4] bx lr ENDPROC(return_to_fel)

This seems to work for me. However we probably might try to skip restoring some of these registers. Also somebody might want to review the order in which the registers should be restored.

diff --git a/arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds b/arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds deleted file mode 100644 index 928b7c1..0000000 --- a/arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds +++ /dev/null @@ -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*) }

-} diff --git a/arch/arm/include/asm/arch-sunxi/sys_proto.h b/arch/arm/include/asm/arch-sunxi/sys_proto.h index c3e636e..60a5bd8 100644 --- a/arch/arm/include/asm/arch-sunxi/sys_proto.h +++ b/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 diff --git a/board/sunxi/Kconfig b/board/sunxi/Kconfig index 4a21589..3eab81f 100644 --- a/board/sunxi/Kconfig +++ b/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" diff --git a/include/configs/sunxi-common.h b/include/configs/sunxi-common.h index 6cfd7e1..3becb4f 100644 --- a/include/configs/sunxi-common.h +++ b/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 */

@@ -146,10 +144,10 @@ #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 */

diff --git a/scripts/Makefile.spl b/scripts/Makefile.spl index ecf3037..5a1962b 100644 --- a/scripts/Makefile.spl +++ b/scripts/Makefile.spl @@ -153,10 +153,8 @@ 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

One more theoretical concern is the placement of the stack in the legacy FEL mode after your changes. Now it seems to be moved to 0x8000, which might be fine though, according to the memory map from

https://github.com/hno/Allwinner-Info/blob/master/FEL-usb/USB-protocol.txt

If we want to preserve the old behaviour, then we would need to place it around 0x5d00.