Re: [PATCH 2/2] ARM: berlin: add SMP support
From: Antoine TÃnart
Date: Fri Mar 21 2014 - 05:21:03 EST
On 20/03/2014 21:39, Sebastian Hesselbarth wrote:
This adds SMP support to Marvell Berlin2 SoCs. Secondary CPUs boot into
BootROM, wait for interrupt, and read SW generic register 1 with actual
boot code address. Synchronization by holding pen is copied from
plat-versatile and mach-prima2.
Signed-off-by: Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
Acked-by: Antoine TÃnart <antoine.tenart@xxxxxxxxxxxxxxxxxx>
Also tested on the BG2Q,
Tested-by: Antoine TÃnart <antoine.tenart@xxxxxxxxxxxxxxxxxx>
---
Cc: Russell King <linux@xxxxxxxxxxxxxxxx>
Cc: Antoine Tenart <antoine.tenart@xxxxxxxxxxxxxxxxxx>
Cc: Alexandre Belloni <alexandre.belloni@xxxxxxxxxxxxxxxxxx>
Cc: linux-arm-kernel@xxxxxxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
arch/arm/mach-berlin/Kconfig | 1 +
arch/arm/mach-berlin/Makefile | 1 +
arch/arm/mach-berlin/berlin.c | 3 +
arch/arm/mach-berlin/common.h | 18 ++++++
arch/arm/mach-berlin/headsmp.S | 43 +++++++++++++
arch/arm/mach-berlin/platsmp.c | 139 +++++++++++++++++++++++++++++++++++++++++
6 files changed, 205 insertions(+)
create mode 100644 arch/arm/mach-berlin/common.h
create mode 100644 arch/arm/mach-berlin/headsmp.S
create mode 100644 arch/arm/mach-berlin/platsmp.c
diff --git a/arch/arm/mach-berlin/Kconfig b/arch/arm/mach-berlin/Kconfig
index 7a02d222c378..eecec99c3096 100644
--- a/arch/arm/mach-berlin/Kconfig
+++ b/arch/arm/mach-berlin/Kconfig
@@ -15,6 +15,7 @@ config MACH_BERLIN_BG2
bool "Marvell Armada 1500 (BG2)"
select CACHE_L2X0
select CPU_PJ4B
+ select HAVE_ARM_SCU if SMP
select HAVE_ARM_TWD if SMP
select HAVE_SMP
diff --git a/arch/arm/mach-berlin/Makefile b/arch/arm/mach-berlin/Makefile
index ab69fe956f49..e11b1b0be4dd 100644
--- a/arch/arm/mach-berlin/Makefile
+++ b/arch/arm/mach-berlin/Makefile
@@ -1 +1,2 @@
obj-y += berlin.o
+obj-$(CONFIG_SMP) += platsmp.o headsmp.o
diff --git a/arch/arm/mach-berlin/berlin.c b/arch/arm/mach-berlin/berlin.c
index 025bcb5473eb..1bbca793174d 100644
--- a/arch/arm/mach-berlin/berlin.c
+++ b/arch/arm/mach-berlin/berlin.c
@@ -18,6 +18,8 @@
#include <asm/hardware/cache-l2x0.h>
#include <asm/mach/arch.h>
+#include "common.h"
+
static void __init berlin_init_machine(void)
{
/*
@@ -36,4 +38,5 @@ static const char * const berlin_dt_compat[] = {
DT_MACHINE_START(BERLIN_DT, "Marvell Berlin")
.dt_compat = berlin_dt_compat,
.init_machine = berlin_init_machine,
+ .smp = smp_ops(berlin_smp_ops),
MACHINE_END
diff --git a/arch/arm/mach-berlin/common.h b/arch/arm/mach-berlin/common.h
new file mode 100644
index 000000000000..57c97669af0a
--- /dev/null
+++ b/arch/arm/mach-berlin/common.h
@@ -0,0 +1,18 @@
+/*
+ * Marvell Berlin SoCs common include.
+ *
+ * Sebastian Hesselbarth <sebastian.hesselbarth@xxxxxxxxx>
+ *
+ * This file is licensed under the terms of the GNU General Public
+ * License version 2. This program is licensed "as is" without any
+ * warranty of any kind, whether express or implied.
+ */
+
+#ifndef __ARCH_BERLIN_COMMON_H
+#define __ARCH_BERLIN_COMMON_H
+
+extern void berlin_secondary_startup(void);
+
+extern struct smp_operations berlin_smp_ops;
+
+#endif
diff --git a/arch/arm/mach-berlin/headsmp.S b/arch/arm/mach-berlin/headsmp.S
new file mode 100644
index 000000000000..bd187257fefd
--- /dev/null
+++ b/arch/arm/mach-berlin/headsmp.S
@@ -0,0 +1,43 @@
+/*
+ * linux/arch/arm/mach-berlin/headsmp.S
+ *
+ * Based on linux/arch/arm/mach-prima2/headsmp.S
+ *
+ * Copyright (c) 2003 ARM Limited
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/linkage.h>
+#include <linux/init.h>
+#include <asm/assembler.h>
+
+/*
+ * Entry point for secondary CPUs, this provides a "holding pen" into which
+ * all secondary cores are held until we're ready for them to initialise.
+ */
+ENTRY(berlin_secondary_startup)
+ ARM_BE8(setend be)
+ bl v7_invalidate_l1
+ mrc p15, 0, r0, c0, c0, 5
+ and r0, r0, #15
+ adr r4, 1f
+ ldmia r4, {r5, r6}
+ sub r4, r4, r5
+ add r6, r6, r4
+pen: ldr r7, [r6]
+ cmp r7, r0
+ bne pen
+
+ /*
+ * we've been released from the holding pen: secondary_stack
+ * should now contain the SVC stack for this core
+ */
+ b secondary_startup
+ENDPROC(berlin_secondary_startup)
+
+ .align
+1: .long .
+ .long pen_release
diff --git a/arch/arm/mach-berlin/platsmp.c b/arch/arm/mach-berlin/platsmp.c
new file mode 100644
index 000000000000..5c83941b0918
--- /dev/null
+++ b/arch/arm/mach-berlin/platsmp.c
@@ -0,0 +1,139 @@
+/*
+ * linux/arch/arm/mach-berlin/platsmp.c
+ *
+ * Based on linux/arch/arm/plat-versatile/platsmp.c
+ *
+ * Copyright (C) 2002 ARM Ltd.
+ * All Rights Reserved
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+*/
+
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/errno.h>
+#include <linux/io.h>
+#include <linux/jiffies.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/smp.h>
+
+#include <asm/cacheflush.h>
+#include <asm/smp_plat.h>
+#include <asm/smp_scu.h>
+
+#include "common.h"
+
+/*
+ * Write pen_release in a way that is guaranteed to be visible to all
+ * observers, irrespective of whether they're taking part in coherency
+ * or not. This is necessary for the hotplug code to work reliably.
+ */
+static void write_pen_release(int val)
+{
+ pen_release = val;
+ /* write and flush pen_release to memory */
+ smp_wmb();
+ sync_cache_w(&pen_release);
+}
+
+static DEFINE_SPINLOCK(boot_lock);
+
+static void berlin_secondary_init(unsigned int cpu)
+{
+ /*
+ * let the primary processor know we're out of the
+ * pen, then head off into the C entry point
+ */
+ write_pen_release(-1);
+
+ /*
+ * Synchronise with the boot thread.
+ */
+ spin_lock(&boot_lock);
+ spin_unlock(&boot_lock);
+}
+
+static int berlin_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+ unsigned long timeout;
+
+ /*
+ * Set synchronisation state between this boot processor
+ * and the secondary one
+ */
+ spin_lock(&boot_lock);
+
+ /*
+ * This is really belt and braces; we hold unintended secondary
+ * CPUs in the holding pen until we're ready for them. However,
+ * since we haven't sent them a soft interrupt, they shouldn't
+ * be there.
+ */
+ write_pen_release(cpu_logical_map(cpu));
+
+ /*
+ * Send the secondary CPU a soft interrupt, thereby causing
+ * the boot monitor to read the system wide flags register,
+ * and branch to the address found there.
+ */
+ arch_send_wakeup_ipi_mask(cpumask_of(cpu));
+
+ timeout = jiffies + (1 * HZ);
+ while (time_before(jiffies, timeout)) {
+ /* pen_release SMP read barrier */
+ smp_rmb();
+ if (pen_release == -1)
+ break;
+
+ udelay(10);
+ }
+
+ /*
+ * now the secondary core is starting up let it run its
+ * calibrations, then wait for it to finish
+ */
+ spin_unlock(&boot_lock);
+
+ return pen_release != -1 ? -ENOSYS : 0;
+}
+
+static void __init berlin_smp_prepare_cpus(unsigned int max_cpus)
+{
+ struct device_node *np;
+ void __iomem *scu_base;
+ void __iomem *gpr_base;
+
+ np = of_find_compatible_node(NULL, NULL, "arm,cortex-a9-scu");
+ scu_base = of_iomap(np, 0);
+ of_node_put(np);
+ if (!scu_base)
+ return;
+
+ np = of_find_compatible_node(NULL, NULL, "marvell,berlin-generic-regs");
+ gpr_base = of_iomap(np, 0);
+ of_node_put(np);
+ if (!gpr_base) {
+ iounmap(scu_base);
+ return;
+ }
+
+ /*
+ * Enable SCU and write the address of secondary startup into the
+ * global SW generic register 1. The secondary CPU waits for an
+ * interrupt and then branches to the address stored in the SW
+ * generic register 1.
+ */
+ scu_enable(scu_base);
+ writel(virt_to_phys(berlin_secondary_startup), gpr_base + 0x04);
+ iounmap(scu_base);
+ iounmap(gpr_base);
+}
+
+struct smp_operations berlin_smp_ops __initdata = {
+ .smp_prepare_cpus = berlin_smp_prepare_cpus,
+ .smp_secondary_init = berlin_secondary_init,
+ .smp_boot_secondary = berlin_boot_secondary,
+};
--
Antoine TÃnart, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com
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