sunxi: move Cortex SMPEN setting into start.S

According to their TRMs, Cortex ARMv7 CPUs with SMP support require the
ACTLR.SMPEN bit to be set as early as possible, before any cache or TLB
maintenance operations are done. As we do those things still in start.S,
we need to move the SMPEN bit setting there, too.

This introduces a new ARMv7 wide symbol and code to set bit 6 in ACTLR
very early in start.S, and moves sunxi boards over to use that instead
of the custom code we had in our board.c file (where it was called
technically too late).

In practice we got away with this so far, because at this point all the
other cores were still in reset, so any broadcasting would have been
ignored anyway. But it is architecturally cleaner to do it early, and
we move a core specific piece of code out of board.c.

This also gets rid of the ARM_CORTEX_CPU_IS_UP kludge I introduced a few
years back, and moves the respective logic into the new Kconfig entry.

Signed-off-by: Andre Przywara <andre.przywara@arm.com>

arch/arm/Kconfig

@@ -452,9 +452,6 @@ config ENABLE_ARM_SOC_BOOT0_HOOK
 	  values, then choose this option, and create a file included as
 	  <asm/arch/boot0.h> which contains the required assembler code.
 
-config ARM_CORTEX_CPU_IS_UP
-	bool
-
 config USE_ARCH_MEMCPY
 	bool "Use an assembly optimized implementation of memcpy"
 	default y if !ARM64

arch/arm/cpu/armv7/Kconfig

@@ -76,4 +76,9 @@ config ARMV7_LPAE
 	Say Y here to use the long descriptor page table format. This is
 	required if U-Boot runs in HYP mode.
 
+config SPL_ARMV7_SET_CORTEX_SMPEN
+	bool
+	help
+	  Enable the ARM Cortex ACTLR.SMP enable bit on SPL startup.
+
 endif

arch/arm/cpu/armv7/start.S

@@ -173,6 +173,17 @@ ENDPROC(switch_to_hypervisor)
  *
  *************************************************************************/
 ENTRY(cpu_init_cp15)
+
+#if CONFIG_IS_ENABLED(ARMV7_SET_CORTEX_SMPEN)
+	/*
+	 * The Arm Cortex-A7 TRM says this bit must be enabled before
+	 * "any cache or TLB maintenance operations are performed".
+	 */
+	mrc	p15, 0, r0, c1, c0, 1	@ read auxilary control register
+	orr	r0, r0, #1 << 6		@ set SMP bit to enable coherency
+	mcr	p15, 0, r0, c1, c0, 1	@ write auxilary control register
+#endif
+
 	/*
 	 * Invalidate L1 I/D
 	 */

arch/arm/mach-sunxi/Kconfig

@@ -186,7 +186,6 @@ choice
 config MACH_SUN4I
 	bool "sun4i (Allwinner A10)"
 	select CPU_V7A
-	select ARM_CORTEX_CPU_IS_UP
 	select PHY_SUN4I_USB
 	select DRAM_SUN4I
 	select SUNXI_GEN_SUN4I
@@ -197,7 +196,6 @@ config MACH_SUN4I
 config MACH_SUN5I
 	bool "sun5i (Allwinner A13)"
 	select CPU_V7A
-	select ARM_CORTEX_CPU_IS_UP
 	select DRAM_SUN4I
 	select PHY_SUN4I_USB
 	select SUNXI_GEN_SUN4I
@@ -212,6 +210,7 @@ config MACH_SUN6I
 	select CPU_V7_HAS_NONSEC
 	select CPU_V7_HAS_VIRT
 	select ARCH_SUPPORT_PSCI
+	select SPL_ARMV7_SET_CORTEX_SMPEN
 	select DRAM_SUN6I
 	select PHY_SUN4I_USB
 	select SPL_I2C
@@ -227,6 +226,7 @@ config MACH_SUN7I
 	select CPU_V7_HAS_NONSEC
 	select CPU_V7_HAS_VIRT
 	select ARCH_SUPPORT_PSCI
+	select SPL_ARMV7_SET_CORTEX_SMPEN
 	select DRAM_SUN4I
 	select PHY_SUN4I_USB
 	select SUNXI_GEN_SUN4I
@@ -315,6 +315,7 @@ config MACH_SUN8I_V3S
 config MACH_SUN9I
 	bool "sun9i (Allwinner A80)"
 	select CPU_V7A
+	select SPL_ARMV7_SET_CORTEX_SMPEN
 	select DRAM_SUN9I
 	select SPL_I2C
 	select SUN6I_PRCM
@@ -365,6 +366,7 @@ endchoice
 # The sun8i SoCs share a lot, this helps to avoid a lot of "if A23 || A33"
 config MACH_SUN8I
 	bool
+	select SPL_ARMV7_SET_CORTEX_SMPEN if !ARM64
 	select SUN6I_PRCM
 	default y if MACH_SUN8I_A23
 	default y if MACH_SUN8I_A33

arch/arm/mach-sunxi/board.c

@@ -218,15 +218,6 @@ void s_init(void)
 	/* A83T BSP never modifies SUNXI_SRAMC_BASE + 0x44 */
 	/* No H3 BSP, boot0 seems to not modify SUNXI_SRAMC_BASE + 0x44 */
 #endif
-
-#if !defined(CONFIG_ARM_CORTEX_CPU_IS_UP) && !defined(CONFIG_ARM64)
-	/* Enable SMP mode for CPU0, by setting bit 6 of Auxiliary Ctl reg */
-	asm volatile(
-		"mrc p15, 0, r0, c1, c0, 1\n"
-		"orr r0, r0, #1 << 6\n"
-		"mcr p15, 0, r0, c1, c0, 1\n"
-		::: "r0");
-#endif
 }
 
 #define SUNXI_INVALID_BOOT_SOURCE	-1