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[PATCH RESEND 0/2] arm: berlin: add cpu hotplug support

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  [PATCH RESEND 0/2] arm: berlin: add cpu hotplug support Jisheng Zhang <jszhang@marvell.com> - 2015-09-14 09:00 +0200
    [PATCH RESEND 2/2] arm: berlin: add CPU hotplug support Jisheng Zhang <jszhang@marvell.com> - 2015-09-14 09:00 +0200

#1223862 — [PATCH RESEND 0/2] arm: berlin: add cpu hotplug support

These patches try to add cpu hotplug support for Marvell BG2, BG2Q SoCs.
These SoCs can't power off cpu independently, but we still want cpu hotplug
support for them. However, we need to address "CPU still sat on kernel text"
as pointed out by Mark Rutland[1]. We achieved this by putting the dying CPU
in WFI state after the coherency is disabled, then asserting the dying CPU
reset bit to put the CPU in reset state.

patch1 use non-self-cleared control register to reset cpu. This is to prepare
for the next cpu hotplug commit.

patch2 adds the cpu hotplug support finally.


[1] http://lists.infradead.org/pipermail/linux-arm-kernel/2015-May/342642.html


Jisheng Zhang (2):
  arm: berlin: use non-self-cleared reset register to reset cpu
  arm: berlin: add CPU hotplug support

 arch/arm/mach-berlin/platsmp.c | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

-- 
2.5.1

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#1223863 — [PATCH RESEND 2/2] arm: berlin: add CPU hotplug support

Add cpu hotplug support for berlin SoCs such as BG2 and BG2Q. These SoC
don't support power off cpu independently, but we also want cpu hotplug
support in these SoCs. We achieve this goal by putting the dying CPU in
WFI state after the coherency is disabled, then asserting the dying CPU
reset bit to put the CPU in reset state.

Signed-off-by: Jisheng Zhang <jszhang@marvell.com>
---
 arch/arm/mach-berlin/platsmp.c | 25 +++++++++++++++++++++++++
 1 file changed, 25 insertions(+)

diff --git a/arch/arm/mach-berlin/platsmp.c b/arch/arm/mach-berlin/platsmp.c
index bde327b..c1e0540 100644
--- a/arch/arm/mach-berlin/platsmp.c
+++ b/arch/arm/mach-berlin/platsmp.c
@@ -14,6 +14,7 @@
 #include <linux/of_address.h>
 
 #include <asm/cacheflush.h>
+#include <asm/cp15.h>
 #include <asm/smp_plat.h>
 #include <asm/smp_scu.h>
 
@@ -93,8 +94,32 @@ unmap_scu:
 	iounmap(scu_base);
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+static void berlin_cpu_die(unsigned int cpu)
+{
+	v7_exit_coherency_flush(louis);
+	while (1)
+		cpu_do_idle();
+}
+
+static int berlin_cpu_kill(unsigned int cpu)
+{
+	u32 val;
+
+	val = readl(cpu_ctrl + CPU_RESET);
+	val &= ~BIT(cpu_logical_map(cpu));
+	writel(val, cpu_ctrl + CPU_RESET);
+
+	return 1;
+}
+#endif
+
 static struct smp_operations berlin_smp_ops __initdata = {
 	.smp_prepare_cpus	= berlin_smp_prepare_cpus,
 	.smp_boot_secondary	= berlin_boot_secondary,
+#ifdef CONFIG_HOTPLUG_CPU
+	.cpu_die		= berlin_cpu_die,
+	.cpu_kill		= berlin_cpu_kill,
+#endif
 };
 CPU_METHOD_OF_DECLARE(berlin_smp, "marvell,berlin-smp", &berlin_smp_ops);
-- 
2.5.1

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