On Sun, 1 Feb 2015 09:28:36 -0700 Simon Glass sjg@chromium.org wrote:
Hi,
On 30 January 2015 at 04:58, Siarhei Siamashka siarhei.siamashka@gmail.com wrote:
The commit f630974ccb3ce93e9607a3354e9acb266a8b7e95 'sunxi: Move SPL s_init() code to board_init_f()' broke the FEL boot mode.
This patch moves the DRAM initialization back to s_init() and introduces an assembly entry point for FEL in order to provide guaranteed initialization of the gdata pointer (r9). The assembly entry point is also needed to ensure that the SPL code starts executing in ARM mode.
Because the sunxi board_init_f() does not contain anything that is not already done by the default board_init_f(), it is removed too.
Signed-off-by: Siarhei Siamashka siarhei.siamashka@gmail.com
arch/arm/cpu/armv7/sunxi/Makefile | 1 + arch/arm/cpu/armv7/sunxi/board.c | 26 ++++++++++---------------- arch/arm/cpu/armv7/sunxi/start_fel.S | 16 ++++++++++++++++ arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds | 3 ++- 4 files changed, 29 insertions(+), 17 deletions(-) create mode 100644 arch/arm/cpu/armv7/sunxi/start_fel.S
diff --git a/arch/arm/cpu/armv7/sunxi/Makefile b/arch/arm/cpu/armv7/sunxi/Makefile index 48db744..e0d413d 100644 --- a/arch/arm/cpu/armv7/sunxi/Makefile +++ b/arch/arm/cpu/armv7/sunxi/Makefile @@ -40,5 +40,6 @@ obj-$(CONFIG_MACH_SUN7I) += dram_sun4i.o obj-$(CONFIG_MACH_SUN8I) += dram_sun8i.o ifdef CONFIG_SPL_FEL obj-y += start.o +extra-y += start_fel.o endif endif diff --git a/arch/arm/cpu/armv7/sunxi/board.c b/arch/arm/cpu/armv7/sunxi/board.c index 6e28bcd..ea6cb60 100644 --- a/arch/arm/cpu/armv7/sunxi/board.c +++ b/arch/arm/cpu/armv7/sunxi/board.c @@ -85,6 +85,16 @@ void s_init(void) timer_init(); gpio_init(); i2c_init_board();
+#ifdef CONFIG_SPL_BUILD
preloader_console_init();s_init() is called before we have global_data, so you can't use a console.
Oh, but somehow it just works for me.
+#ifdef CONFIG_SPL_I2C_SUPPORT
/* Needed early by sunxi_board_init if PMU is enabled */i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);+#endif
sunxi_board_init();+#endif
Why do you need this code here?
The i2c_init() call is needed to initialize the PMIC as the comment says. The PMIC is needed to set correct voltages, necessary for the DRAM controller.
And the sunxi_board_init() initializes DRAM.
Can it not go in board_init_f()?
Then we probably would need a special stripped down FEL variant of board_init_f(), which makes the code a bit more messy.
}
#ifdef CONFIG_SPL_BUILD @@ -103,22 +113,6 @@ u32 spl_boot_mode(void) { return MMCSD_MODE_RAW; }
-void board_init_f(ulong dummy) -{
preloader_console_init();-#ifdef CONFIG_SPL_I2C_SUPPORT
/* Needed early by sunxi_board_init if PMU is enabled */i2c_init(CONFIG_SYS_I2C_SPEED, CONFIG_SYS_I2C_SLAVE);-#endif
sunxi_board_init();/* Clear the BSS. */memset(__bss_start, 0, __bss_end - __bss_start);board_init_r(NULL, 0);-} #endif
void reset_cpu(ulong addr) diff --git a/arch/arm/cpu/armv7/sunxi/start_fel.S b/arch/arm/cpu/armv7/sunxi/start_fel.S new file mode 100644 index 0000000..e1c7cd4 --- /dev/null +++ b/arch/arm/cpu/armv7/sunxi/start_fel.S @@ -0,0 +1,16 @@ +/*
- Entry point of the FEL mode SPL.
- Copyright (c) 2015 Siarhei Siamashka siarhei.siamashka@gmail.com
- SPDX-License-Identifier: GPL-2.0+
- */
+#include <asm-offsets.h> +#include <config.h> +#include <linux/linkage.h>
+ENTRY(_start_fel)
ldr r9, =gdatab s_initNo we don't want global data here, and need to get rid of gdata so we can use driver model, etc.
Appears that I need to educate myself on the global data vs. gdata differences.
Using driver model in the sunxi SPL is a bit challenging because we don't have abundant amounts of SRAM there: http://linux-sunxi.org/SRAM_Controller Without relying on SoC-variant specific SRAM sections, we have 32 KiB for normal SPL, and only ~15 KiB for FEL SPL (the rest is used by the BROM FEL code). And SRAM is very much needed for the other important features.
So far I can see that the pointer to gdata is stored in the r9 register. And gdata resides in the ".data" section, which means that it is initialized to 0 automatically. And this works now, unless I'm misunderstanding something.
I would be more than happy to fix it in a future proof way. However it is very much desired to have a properly functioning FEL boot mode in u-boot 2015.04 and IMHO a quick hack relying on the legacy gdata feature might be not the worst possible option today.
+ENDPROC(_start_fel) diff --git a/arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds b/arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds index 928b7c1..beb8900 100644 --- a/arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds +++ b/arch/arm/cpu/armv7/sunxi/u-boot-spl-fel.lds @@ -6,7 +6,7 @@ */ OUTPUT_FORMAT("elf32-littlearm", "elf32-littlearm", "elf32-littlearm") OUTPUT_ARCH(arm) -ENTRY(s_init) +ENTRY(_start_fel) SECTIONS { . = 0x00002000; @@ -14,6 +14,7 @@ SECTIONS . = ALIGN(4); .text : {
arch/arm/cpu/armv7/sunxi/start_fel.o (.text) *(.text.s_init)Why does this have to jump to a special s_init? Can it not just start SPL normally as it does on Tegra, Exynos, etc?
*(.text*) }There has to be a better way of making this work. Also do you have instructions on how I can try this out on a pcduino3 or other low-cost board?
I understand that we need to fix this, but other archs deal with this within the existing framework, so I'd really like to get sunxi into the same state.
For these parts, see my replies in: http://lists.denx.de/pipermail/u-boot/2015-February/203439.html http://lists.denx.de/pipermail/u-boot/2015-February/203485.html
I'm afraid that we can't always fit the BROM code into the existing frameworks. But maybe some good solution exists for this particular case.