ARM: UniPhier: optimize kicking secondary CPUs code
Currently, the secondary CPU(s) are kicked three times:
Boot ROM ---(kick)--> SPL ---(kick)--> U-boot ---(kick)--> Linux.
It makes the boot sequence very complicated.
This commit merges the first and the second kicks, so the secondary
CPU(s) can directly jump from SPL to Linux.
arch/arm/mach-uniphier/smp.S is no longer necessary.
Linux boot test passed.
Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
diff --git a/arch/arm/mach-uniphier/lowlevel_init.S b/arch/arm/mach-uniphier/lowlevel_init.S
index 4a23ea4..825b160 100644
--- a/arch/arm/mach-uniphier/lowlevel_init.S
+++ b/arch/arm/mach-uniphier/lowlevel_init.S
@@ -48,6 +48,25 @@
bl enable_mmu
#ifdef CONFIG_UNIPHIER_SMP
+secondary_startup:
+ /*
+ * Entry point for secondary CPUs
+ *
+ * The Boot ROM has already enabled MMU for the secondary CPUs as well
+ * as for the primary one. The MMU table embedded in the Boot ROM
+ * prohibits the DRAM access, so it is impossible to bring the
+ * secondary CPUs into DRAM directly. They must jump here into SPL,
+ * which is run on L2 cache.
+ *
+ * Boot Sequence
+ * [primary CPU] [secondary CPUs]
+ * start from Boot ROM start from Boot ROM
+ * jump to SPL sleep in Boot ROM
+ * kick secondaries ---(sev)---> jump to SPL
+ * jump to U-Boot main sleep in SPL
+ * jump to Linux
+ * kick secondaries ---(sev)---> jump to Linux
+ */
/*
* ACTLR (Auxiliary Control Register) for Cortex-A9
* bit[9] Parity on
@@ -68,17 +87,28 @@
and r0, r0, #0x3
cmp r0, #0x0
beq primary_cpu
- ldr r1, =ROM_BOOT_ROMRSV2
+ /* only for secondary CPUs */
+ ldr r1, =ROM_BOOT_ROMRSV2 @ The last data access to L2 cache
+ mrc p15, 0, r0, c1, c0, 0 @ SCTLR (System Control Register)
+ orr r0, r0, #CR_I @ Enable ICache
+ bic r0, r0, #(CR_C | CR_M) @ MMU and Dcache must be disabled
+ mcr p15, 0, r0, c1, c0, 0 @ before jumping to Linux
mov r0, #0
str r0, [r1]
-0: wfe
- ldr r0, [r1]
+ b 1f
+ /*
+ * L2 cache is shared among all the CPUs and it might be disabled by
+ * the primary one. Before that, the following 5 lines must be cached
+ * on the Icaches of the secondary CPUs.
+ */
+0: wfe @ kicked by Linux
+1: ldr r0, [r1]
cmp r0, #0
- beq 0b
- bx r0 @ r0: entry point of U-Boot main for the secondary CPU
+ bxne r0 @ r0: Linux entry for secondary CPUs
+ b 0b
primary_cpu:
ldr r1, =ROM_BOOT_ROMRSV2
- ldr r0, =_start @ entry for the secondary CPU
+ ldr r0, =secondary_startup
str r0, [r1]
ldr r0, [r1] @ make sure str is complete before sev
sev @ kick the secondary CPU