[PATCH 1/2] ARM: SH-Mobile: sh73a0: Secondary CPUs handle own SCU flags

* [PATCH 1/2] ARM: SH-Mobile: sh73a0: Secondary CPUs handle own SCU flags
@ 2012-12-06 12:08 ` Bastian Hecht
  0 siblings, 0 replies; 22+ messages in thread
From: Bastian Hecht @ 2012-12-06 12:08 UTC (permalink / raw)
  To: linux-arm-kernel

From: Bastian Hecht <hechtb@gmail.com>

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>
---
 arch/arm/mach-shmobile/Makefile              |    2 +-
 arch/arm/mach-shmobile/headsmp-sh73a0.S      |   50 ++++++++++++++++++++++++++
 arch/arm/mach-shmobile/include/mach/common.h |    1 +
 arch/arm/mach-shmobile/smp-sh73a0.c          |   30 +++-------------
 4 files changed, 56 insertions(+), 27 deletions(-)
 create mode 100644 arch/arm/mach-shmobile/headsmp-sh73a0.S

diff --git a/arch/arm/mach-shmobile/Makefile b/arch/arm/mach-shmobile/Makefile
index fe2c97c..a7beb61 100644
--- a/arch/arm/mach-shmobile/Makefile
+++ b/arch/arm/mach-shmobile/Makefile
@@ -17,7 +17,7 @@ obj-$(CONFIG_ARCH_EMEV2)	+= setup-emev2.o clock-emev2.o
 # SMP objects
 smp-y				:= platsmp.o headsmp.o
 smp-$(CONFIG_HOTPLUG_CPU)	+= hotplug.o
-smp-$(CONFIG_ARCH_SH73A0)	+= smp-sh73a0.o
+smp-$(CONFIG_ARCH_SH73A0)	+= smp-sh73a0.o headsmp-sh73a0.o
 smp-$(CONFIG_ARCH_R8A7779)	+= smp-r8a7779.o
 smp-$(CONFIG_ARCH_EMEV2)	+= smp-emev2.o
 
diff --git a/arch/arm/mach-shmobile/headsmp-sh73a0.S b/arch/arm/mach-shmobile/headsmp-sh73a0.S
new file mode 100644
index 0000000..bec4c0d
--- /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)
diff --git a/arch/arm/mach-shmobile/include/mach/common.h b/arch/arm/mach-shmobile/include/mach/common.h
index d47e215..f2e2c29 100644
--- a/arch/arm/mach-shmobile/include/mach/common.h
+++ b/arch/arm/mach-shmobile/include/mach/common.h
@@ -54,6 +54,7 @@ extern void sh73a0_add_early_devices(void);
 extern void sh73a0_add_standard_devices(void);
 extern void sh73a0_clock_init(void);
 extern void sh73a0_pinmux_init(void);
+extern void sh73a0_secondary_vector(void);
 extern struct clk sh73a0_extal1_clk;
 extern struct clk sh73a0_extal2_clk;
 extern struct clk sh73a0_extcki_clk;
diff --git a/arch/arm/mach-shmobile/smp-sh73a0.c b/arch/arm/mach-shmobile/smp-sh73a0.c
index 624f00f..5e36f5d 100644
--- a/arch/arm/mach-shmobile/smp-sh73a0.c
+++ b/arch/arm/mach-shmobile/smp-sh73a0.c
@@ -41,9 +41,6 @@ static void __iomem *scu_base_addr(void)
 	return (void __iomem *)0xf0000000;
 }
 
-static DEFINE_SPINLOCK(scu_lock);
-static unsigned long tmp;
-
 #ifdef CONFIG_HAVE_ARM_TWD
 static DEFINE_TWD_LOCAL_TIMER(twd_local_timer, 0xf0000600, 29);
 void __init sh73a0_register_twd(void)
@@ -52,20 +49,6 @@ void __init sh73a0_register_twd(void)
 }
 #endif
 
-static void modify_scu_cpu_psr(unsigned long set, unsigned long clr)
-{
-	void __iomem *scu_base = scu_base_addr();
-
-	spin_lock(&scu_lock);
-	tmp = __raw_readl(scu_base + 8);
-	tmp &= ~clr;
-	tmp |= set;
-	spin_unlock(&scu_lock);
-
-	/* disable cache coherency after releasing the lock */
-	__raw_writel(tmp, scu_base + 8);
-}
-
 static unsigned int __init sh73a0_get_core_count(void)
 {
 	void __iomem *scu_base = scu_base_addr();
@@ -82,9 +65,6 @@ static int __cpuinit sh73a0_boot_secondary(unsigned int cpu, struct task_struct
 {
 	cpu = cpu_logical_map(cpu);
 
-	/* enable cache coherency */
-	modify_scu_cpu_psr(0, 3 << (cpu * 8));
-
 	if (((__raw_readl(PSTR) >> (4 * cpu)) & 3) = 3)
 		__raw_writel(1 << cpu, WUPCR);	/* wake up */
 	else
@@ -95,16 +75,14 @@ static int __cpuinit sh73a0_boot_secondary(unsigned int cpu, struct task_struct
 
 static void __init sh73a0_smp_prepare_cpus(unsigned int max_cpus)
 {
-	int cpu = cpu_logical_map(0);
-
 	scu_enable(scu_base_addr());
 
-	/* Map the reset vector (in headsmp.S) */
+	/* Map the reset vector (in headsmp-sh73a0.S) */
 	__raw_writel(0, APARMBAREA);      /* 4k */
-	__raw_writel(__pa(shmobile_secondary_vector), SBAR);
+	__raw_writel(__pa(sh73a0_secondary_vector), SBAR);
 
-	/* enable cache coherency on CPU0 */
-	modify_scu_cpu_psr(0, 3 << (cpu * 8));
+	/* enable cache coherency on booting CPU */
+	scu_power_mode(scu_base_addr(), SCU_PM_NORMAL);
 }
 
 static void __init sh73a0_smp_init_cpus(void)
-- 
1.7.9.5


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