linux-kernel - [PATCH v2 16/20] ARM: mmp: add SMP support

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Date:   Thu, 22 Aug 2019 11:26:39 +0200
From:   Lubomir Rintel <lkundrak@...sk>
To:     Olof Johansson <olof@...om.net>
Cc:     Rob Herring <robh+dt@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Jason Cooper <jason@...edaemon.net>,
        Marc Zyngier <maz@...nel.org>,
        Kishon Vijay Abraham I <kishon@...com>,
        Russell King <linux@...linux.org.uk>,
        Michael Turquette <mturquette@...libre.com>,
        Stephen Boyd <sboyd@...nel.org>, devicetree@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-clk@...r.kernel.org, Lubomir Rintel <lkundrak@...sk>
Subject: [PATCH v2 16/20] ARM: mmp: add SMP support

Used to bring up the second core on MMP3.

Signed-off-by: Lubomir Rintel <lkundrak@...sk>

---
Changes since v1:
- Wrap SW_BRANCH_VIRT_ADDR with __pa_symbol()

 arch/arm/mach-mmp/Makefile  |  3 +++
 arch/arm/mach-mmp/platsmp.c | 33 +++++++++++++++++++++++++++++++++
 2 files changed, 36 insertions(+)
 create mode 100644 arch/arm/mach-mmp/platsmp.c

diff --git a/arch/arm/mach-mmp/Makefile b/arch/arm/mach-mmp/Makefile
index 322c1c97dc900..7b3a7f979eece 100644
--- a/arch/arm/mach-mmp/Makefile
+++ b/arch/arm/mach-mmp/Makefile
@@ -22,6 +22,9 @@ ifeq ($(CONFIG_PM),y)
 obj-$(CONFIG_CPU_PXA910)	+= pm-pxa910.o
 obj-$(CONFIG_CPU_MMP2)		+= pm-mmp2.o
 endif
+ifeq ($(CONFIG_SMP),y)
+obj-$(CONFIG_MACH_MMP3_DT)	+= platsmp.o
+endif
 
 # board support
 obj-$(CONFIG_MACH_ASPENITE)	+= aspenite.o
diff --git a/arch/arm/mach-mmp/platsmp.c b/arch/arm/mach-mmp/platsmp.c
new file mode 100644
index 0000000000000..98d5ef23623cb
--- /dev/null
+++ b/arch/arm/mach-mmp/platsmp.c
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Copyright (C) 2019 Lubomir Rintel <lkundrak@...sk>
+ */
+#include <linux/io.h>
+#include <asm/smp_scu.h>
+#include <asm/smp.h>
+#include "addr-map.h"
+
+#define SW_BRANCH_VIRT_ADDR	CIU_REG(0x24)
+
+static int mmp3_boot_secondary(unsigned int cpu, struct task_struct *idle)
+{
+	/*
+	 * Apparently, the boot ROM on the second core spins on this
+	 * register becoming non-zero and then jumps to the address written
+	 * there. No IPIs involved.
+	 */
+	__raw_writel(virt_to_phys(secondary_startup),
+			__pa_symbol(SW_BRANCH_VIRT_ADDR));
+	return 0;
+}
+
+static void mmp3_smp_prepare_cpus(unsigned int max_cpus)
+{
+	scu_enable(SCU_VIRT_BASE);
+}
+
+static const struct smp_operations mmp3_smp_ops __initconst = {
+	.smp_prepare_cpus	= mmp3_smp_prepare_cpus,
+	.smp_boot_secondary	= mmp3_boot_secondary,
+};
+CPU_METHOD_OF_DECLARE(mmp3_smp, "marvell,mmp3-smp", &mmp3_smp_ops);
-- 
2.21.0