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>

arch/arm/mach-uniphier/Makefile

@@ -22,7 +22,6 @@ obj-$(CONFIG_BOARD_EARLY_INIT_R) += board_early_init_r.o
 obj-$(CONFIG_BOARD_LATE_INIT) += board_late_init.o
 obj-y += reset.o
 obj-y += cache_uniphier.o
-obj-$(CONFIG_UNIPHIER_SMP) += smp.o
 obj-$(CONFIG_CMD_PINMON) += cmd_pinmon.o
 obj-$(CONFIG_CMD_DDRPHY_DUMP) += cmd_ddrphy.o
 

arch/arm/mach-uniphier/cache_uniphier.c

@@ -1,6 +1,7 @@
 /*
  * Copyright (C) 2012-2014 Panasonic Corporation
- *   Author: Masahiro Yamada <yamada.m@jp.panasonic.com>
+ * Copyright (C) 2015      Socionext Inc.
+ *   Author: Masahiro Yamada <yamada.masahiro@socionext.com>
  *
  * SPDX-License-Identifier:	GPL-2.0+
  */
@@ -119,20 +120,10 @@ void v7_outer_cache_disable(void)
 	writel(tmp, SSCC);
 }
 
-void wakeup_secondary(void);
-
 void enable_caches(void)
 {
 	uint32_t reg;
 
-#ifdef CONFIG_UNIPHIER_SMP
-	/*
-	 * The secondary CPU must move to DDR,
-	 * before L2 disable.
-	 * On SPL, the Page Table is located on the L2.
-	 */
-	wakeup_secondary();
-#endif
 	/*
 	 * UniPhier SoCs must use L2 cache for init stack pointer.
 	 * We disable L2 and L1 in this order.

arch/arm/mach-uniphier/lowlevel_init.S

@@ -48,6 +48,25 @@ ENTRY(lowlevel_init)
 	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 @@ ENTRY(lowlevel_init)
 	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

arch/arm/mach-uniphier/smp.S

@@ -1,54 +0,0 @@
-/*
- * Copyright (C) 2013 Panasonic Corporation
- *   Author: Masahiro Yamada <yamada.m@jp.panasonic.com>
- *
- * SPDX-License-Identifier:	GPL-2.0+
- */
-
-#include <config.h>
-#include <linux/linkage.h>
-#include <asm/system.h>
-#include <mach/led.h>
-#include <mach/sbc-regs.h>
-
-/* Entry point of U-Boot main program for the secondary CPU */
-LENTRY(secondary_entry)
-	mrc	p15, 0, r0, c1, c0, 0	@ SCTLR (System Contrl Register)
-	bic	r0, r0, #(CR_C | CR_M)	@ MMU and Dcache disable
-	mcr	p15, 0, r0, c1, c0, 0
-	mcr	p15, 0, r0, c8, c7, 0	@ invalidate TLBs
-	mcr	p15, 0, r0, c7, c5, 0	@ invalidate icache
-	dsb
-	led_write(C,0,,)
-	ldr	r1, =ROM_BOOT_ROMRSV2
-	mov	r0, #0
-	str	r0, [r1]
-0:	wfe
-	ldr	r4, [r1]		@ r4: entry point for secondary CPUs
-	cmp	r4, #0
-	beq	0b
-	led_write(C, P, U, 1)
-	bx	r4			@ secondary CPUs jump to linux
-ENDPROC(secondary_entry)
-
-ENTRY(wakeup_secondary)
-	ldr	r1, =ROM_BOOT_ROMRSV2
-0:	ldr	r0, [r1]
-	cmp	r0, #0
-	bne	0b
-
-	/* set entry address and send event to the secondary CPU */
-	ldr	r0, =secondary_entry
-	str	r0, [r1]
-	ldr	r0, [r1]	@ make sure store is complete
-	mov	r0, #0x100
-0:	subs	r0, r0, #1	@ I don't know the reason, but without this wait
-	bne	0b		@ fails to wake up the secondary CPU
-	sev
-
-	/* wait until the secondary CPU reach to secondary_entry */
-0:	ldr	r0, [r1]
-	cmp	r0, #0
-	bne	0b
-	bx	lr
-ENDPROC(wakeup_secondary)