Hi, Marek
sorry for possible format issue.
ср, 27 февр. 2019 г., 23:02 Marek Vasut marek.vasut@gmail.com:
On 2/26/19 8:37 PM, Oleksandr wrote:
Hi, Marek
Hi,
>>> +} >>> + >>> +/* >>> + * Reset vector for secondary CPUs. >>> + * This will be mapped at address 0 by SBAR register. >>> + * We need _long_ jump to the physical address. >>> + */ >>> +asm(" .arm\n" >>> + " .align 12\n" >>> + " .globl shmobile_boot_vector\n" >>> + "shmobile_boot_vector:\n" >>> + " ldr r1, 1f\n" >>> + " bx r1\n" >>> + " .type shmobile_boot_vector, %function\n" >>> + " .size shmobile_boot_vector, .-shmobile_boot_vector\n" >>> + " .align 2\n" >>> + " .globl shmobile_boot_fn\n" >>> + "shmobile_boot_fn:\n" >>> + "1: .space 4\n" >>> + " .globl shmobile_boot_size\n" >>> + "shmobile_boot_size:\n" >>> + " .long .-shmobile_boot_vector\n"); >> Why can't this be implemented in C ? > This "reset vector" code was ported from Linux: > >
https://elixir.bootlin.com/linux/v5.0-rc5/source/arch/arm/mach-shmobile/head...
> > > > > Really don't know whether it can be implemented in C. > > I was thinking of moving this code to a separate ASM file in order > not > to mix C and ASM. What do you think about it? U-Boot already has a reset vector code, can't that be reused ?
I don't think. Being honest, I couldn't find an obvious way how to reuse (I assume you meant arch/arm/cpu/armv7/start.S).
Maybe it needs some additional work first ? It seems Altera socfpga somehow uses the U-Boot reset vectors for PSCI, so it should at least be possible.
Could you, please, point me in code? Unfortunately, I wasn't able to find.
The newly turned on secondary CPU entry should be common "psci_cpu_entry", which does proper things.
And this reset vector is just "a small piece of code" to be located in on-chip RAM (with limited size) and used for the jump stub...
We already have the SPL reset vectors in SRAM, maybe that can be recycled somehow ?
The only idea I have, how it may be recycled (not sure whether it will work...)
diff --git a/arch/arm/cpu/armv7/start.S b/arch/arm/cpu/armv7/start.S index 0cb6dd39cc..69acf4677b 100644 --- a/arch/arm/cpu/armv7/start.S +++ b/arch/arm/cpu/armv7/start.S @@ -36,6 +36,12 @@ #endif
reset:
+#if defined(CONFIG_ARMV7_PSCI) && !defined(CONFIG_SPL_BUILD)
b psci_cpu_entry_jump/* return only if this is not "a newly turned on CPU" usingPSCI) */ +#endif
/* Allow the board to save important registers */ b save_boot_paramssave_boot_params_ret: @@ -128,6 +134,21 @@ ENDPROC(switch_to_hypervisor) .weak switch_to_hypervisor #endif
+/*
- Each platform which implements psci_cpu_entry_jump function should
perform
- in the following way:
- If the executing this call CPU is exactly that CPU we are
expecting to be
- powered on, then jump to psci_cpu_entry and never return.
- Otherwise return to the caller.
- */
+#if defined(CONFIG_ARMV7_PSCI) && !defined(CONFIG_SPL_BUILD) +ENTRY(psci_cpu_entry_jump)
movs pc, lr+ENDPROC(psci_cpu_entry_jump) +.weak psci_cpu_entry_jump +#endif
/*************************************************************************
- cpu_init_cp15
What do you think?
It would be much appreciated, if you could provide some hints.
Don't want to be annoying, but it would be really nice to get my questions answered...
I am sorry, I am too busy right now. I will answer that once I can properly study the problem and give you a useful answer.
No problem, I will wait.
Thank you.
-- Best regards, Marek Vasut