[PATCH 2/5] arm: mvebu: Move internal registers in arch_very_early_init() function

[Stefan Roese]

On 06.05.22 11:05, Pali Rohár wrote:
> Moving of internal registers from INTREG_BASE_ADDR_REG to SOC_REGS_PHY_BASE
> needs to be done very early, prior calling any function which may touch
> internal registers, like debug_uart_init().
> 
> So do it earlier in arch_very_early_init() instead of arch_cpu_init().
> 
> Movement is done in proper U-Boot, not in SPL. SPL may return to bootrom
> and bootrom requires internal registers at (old) expected location.
> 
> Signed-off-by: Pali Rohár <pali at kernel.org>
> ---
>   arch/arm/mach-mvebu/Kconfig    |  1 +
>   arch/arm/mach-mvebu/Makefile   |  1 +
>   arch/arm/mach-mvebu/cpu.c      | 31 -------------------------------
>   arch/arm/mach-mvebu/lowlevel.S | 27 +++++++++++++++++++++++++++
>   4 files changed, 29 insertions(+), 31 deletions(-)
>   create mode 100644 arch/arm/mach-mvebu/lowlevel.S
> 
> diff --git a/arch/arm/mach-mvebu/Kconfig b/arch/arm/mach-mvebu/Kconfig
> index a3f273f4f949..98b13d1e336d 100644
> --- a/arch/arm/mach-mvebu/Kconfig
> +++ b/arch/arm/mach-mvebu/Kconfig
> @@ -16,6 +16,7 @@ config ARMADA_32BIT
>   	select SUPPORT_SPL
>   	select TRANSLATION_OFFSET
>   	select SPL_SYS_NO_VECTOR_TABLE if SPL
> +	select ARCH_VERY_EARLY_INIT
>   
>   config ARMADA_64BIT
>   	bool
> diff --git a/arch/arm/mach-mvebu/Makefile b/arch/arm/mach-mvebu/Makefile
> index 1b451889d242..8bd2246325ca 100644
> --- a/arch/arm/mach-mvebu/Makefile
> +++ b/arch/arm/mach-mvebu/Makefile
> @@ -21,6 +21,7 @@ else # CONFIG_ARCH_KIRKWOOD
>   
>   obj-y	= cpu.o
>   obj-y	+= dram.o
> +obj-y	+= lowlevel.o
>   obj-$(CONFIG_DM_RESET) += system-controller.o
>   ifndef CONFIG_SPL_BUILD
>   obj-$(CONFIG_ARMADA_375) += ../../../drivers/ddr/marvell/axp/xor.o
> diff --git a/arch/arm/mach-mvebu/cpu.c b/arch/arm/mach-mvebu/cpu.c
> index 1e893777b292..173d95a760a3 100644
> --- a/arch/arm/mach-mvebu/cpu.c
> +++ b/arch/arm/mach-mvebu/cpu.c
> @@ -413,20 +413,7 @@ static void update_sdram_window_sizes(void)
>   	}
>   }
>   
> -void mmu_disable(void)
> -{
> -	asm volatile(
> -		"mrc p15, 0, r0, c1, c0, 0\n"
> -		"bic r0, #1\n"
> -		"mcr p15, 0, r0, c1, c0, 0\n");
> -}
> -
>   #ifdef CONFIG_ARCH_CPU_INIT
> -static void set_cbar(u32 addr)
> -{
> -	asm("mcr p15, 4, %0, c15, c0" : : "r" (addr));
> -}
> -
>   #define MV_USB_PHY_BASE			(MVEBU_AXP_USB_BASE + 0x800)
>   #define MV_USB_PHY_PLL_REG(reg)		(MV_USB_PHY_BASE | (((reg) & 0xF) << 2))
>   #define MV_USB_X3_BASE(addr)		(MVEBU_AXP_USB_BASE | BIT(11) | \
> @@ -476,24 +463,6 @@ int arch_cpu_init(void)
>   	struct pl310_regs *const pl310 =
>   		(struct pl310_regs *)CONFIG_SYS_PL310_BASE;
>   
> -	/*
> -	 * Only with disabled MMU its possible to switch the base
> -	 * register address on Armada 38x. Without this the SDRAM
> -	 * located at >= 0x4000.0000 is also not accessible, as its
> -	 * still locked to cache.
> -	 */
> -	mmu_disable();
> -
> -	/* Linux expects the internal registers to be at 0xf1000000 */
> -	writel(SOC_REGS_PHY_BASE, INTREG_BASE_ADDR_REG);
> -	set_cbar(SOC_REGS_PHY_BASE + 0xC000);
> -
> -	/*
> -	 * From this stage on, the SoC detection is working. As we have
> -	 * configured the internal register base to the value used
> -	 * in the macros / defines in the U-Boot header (soc.h).
> -	 */
> -
>   	if (mvebu_soc_family() == MVEBU_SOC_A38X) {
>   		/*
>   		 * To fully release / unlock this area from cache, we need
> diff --git a/arch/arm/mach-mvebu/lowlevel.S b/arch/arm/mach-mvebu/lowlevel.S
> new file mode 100644
> index 000000000000..2491310eb0c1
> --- /dev/null
> +++ b/arch/arm/mach-mvebu/lowlevel.S
> @@ -0,0 +1,27 @@
> +/* SPDX-License-Identifier: GPL-2.0+ */
> +
> +#include <config.h>
> +#include <linux/linkage.h>
> +
> +ENTRY(arch_very_early_init)
> +#ifdef CONFIG_ARMADA_38X
> +	/*
> +	 * Only with disabled MMU its possible to switch the base
> +	 * register address on Armada 38x. Without this the SDRAM
> +	 * located at >= 0x4000.0000 is also not accessible, as its
> +	 * still locked to cache.
> +	 */
> +	mrc	p15, 0, r0, c1, c0, 0
> +	bic	r0, #1
> +	mcr	p15, 0, r0, c1, c0, 0
> +#endif

You are disabling the MMU here only for CONFIG_ARMADA_38X. In the
non-asm version removed above, it's disabled in all cases in
arch_cpu_init(). Is this correct? I might be missing something - it's
been quite some time, since I worked on this code.

Thanks,
Stefan

> +
> +	/* Move internal registers from INTREG_BASE_ADDR_REG to SOC_REGS_PHY_BASE */
> +	ldr	r0, =SOC_REGS_PHY_BASE
> +	ldr	r1, =INTREG_BASE_ADDR_REG
> +	str	r0, [r1]
> +	add	r0, r0, #0xC000
> +	mcr	p15, 4, r0, c15, c0
> +
> +	bx lr
> +ENDPROC(arch_very_early_init)

Viele Grüße,
Stefan Roese

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