ARM: SH-Mobile: sh73a0: Secondary CPUs handle own SCU flags

When booting secondary CPUs we have used the main CPU to set up the
Snoop Control Unit flags of these CPUs. It is a cleaner approach
if every CPU takes care of its own flags. We avoid the need for
locking and the program logic is more concise. With this patch the file
headsmp-sh73a0.S is added that contains a startup vector for secondary CPUs
that sets up its own SCU flags.
Further in sh73a0_smp_prepare_cpus() we can rely on the generic ARM helper
scu_power_mode(). This is possible as we don't cross borders anymore (every
CPU handles its own flags) and need no locking. So we can throw out the
needless function modify_scu_cpu_psr().

Signed-off-by: Bastian Hecht <hechtb+renesas@gmail.com>
Signed-off-by: Simon Horman <horms+renesas@verge.net.au>

1 files changed, 50 insertions, 0 deletions

diff --git a/arch/arm/mach-shmobile/headsmp-sh73a0.S b/arch/arm/mach-shmobile/headsmp-sh73a0.S
new file mode 100644
index 000000000000..bec4c0d9b713
--- /dev/null
+++ b/arch/arm/mach-shmobile/headsmp-sh73a0.S
@@ -0,0 +1,50 @@
+/*
+ * SMP support for SoC sh73a0
+ *
+ * Copyright (C) 2012 Bastian Hecht
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR /PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ */
+
+#include <linux/linkage.h>
+#include <linux/init.h>
+#include <asm/memory.h>
+
+	__CPUINIT
+/*
+ * Reset vector for secondary CPUs.
+ *
+ * First we turn on L1 cache coherency for our CPU. Then we jump to
+ * shmobile_invalidate_start that invalidates the cache and hands over control
+ * to the common ARM startup code.
+ * This function will be mapped to address 0 by the SBAR register.
+ * A normal branch is out of range here so we need a long jump. We jump to
+ * the physical address as the MMU is still turned off.
+ */
+	.align	12
+ENTRY(sh73a0_secondary_vector)
+	mrc     p15, 0, r0, c0, c0, 5	@ read MIPDR
+	and	r0, r0, #3		@ mask out cpu ID
+	lsl	r0, r0, #3		@ we will shift by cpu_id * 8 bits
+	mov	r1, #0xf0000000		@ SCU base address
+	ldr	r2, [r1, #8]		@ SCU Power Status Register
+	mov	r3, #3
+	bic	r2, r2, r3, lsl r0	@ Clear bits of our CPU (Run Mode)
+	str	r2, [r1, #8]		@ write back
+
+	ldr	pc, 1f
+1:	.long shmobile_invalidate_start - PAGE_OFFSET + PLAT_PHYS_OFFSET
+ENDPROC(sh73a0_secondary_vector)