arm: mvebu: Add SMP support for Armada XP

This enables SMP support on the Armada XP processor. It adds the
mandatory functions to support SMP such as: the SMP initialization
functions in platsmp.c, the secondary CPU entry point in headsmp.S and
the CPU hotplug initial support in hotplug.c.
Signed-off-by: Yehuda Yitschak <yehuday@marvell.com>
Signed-off-by: Gregory CLEMENT <gregory.clement@free-electrons.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>

arch/arm/configs/mvebu_defconfig

@@ -12,6 +12,9 @@ CONFIG_ARCH_MVEBU=y
 CONFIG_MACH_ARMADA_370=y
 CONFIG_MACH_ARMADA_XP=y
 # CONFIG_CACHE_L2X0 is not set
+# CONFIG_SWP_EMULATE is not set
+CONFIG_SMP=y
+# CONFIG_LOCAL_TIMERS is not set
 CONFIG_AEABI=y
 CONFIG_HIGHMEM=y
 # CONFIG_COMPACTION is not set

arch/arm/mach-mvebu/Kconfig

@@ -21,6 +21,7 @@ menu "Marvell SOC with device tree"
 config MACH_ARMADA_370_XP
 	bool
 	select ARMADA_370_XP_TIMER
+	select HAVE_SMP
 	select CPU_PJ4B
 
 config MACH_ARMADA_370

arch/arm/mach-mvebu/Makefile

@@ -3,3 +3,5 @@ ccflags-$(CONFIG_ARCH_MULTIPLATFORM) := -I$(srctree)/$(src)/include \
 
 obj-y += system-controller.o
 obj-$(CONFIG_MACH_ARMADA_370_XP) += armada-370-xp.o irq-armada-370-xp.o addr-map.o coherency.o coherency_ll.o pmsu.o
+obj-$(CONFIG_SMP)                += platsmp.o headsmp.o
+obj-$(CONFIG_HOTPLUG_CPU)        += hotplug.o

arch/arm/mach-mvebu/armada-370-xp.c

@@ -23,6 +23,7 @@
 #include <asm/mach/time.h>
 #include "armada-370-xp.h"
 #include "common.h"
+#include "coherency.h"
 
 static struct map_desc armada_370_xp_io_desc[] __initdata = {
 	{
@@ -51,6 +52,7 @@ struct sys_timer armada_370_xp_timer = {
 static void __init armada_370_xp_dt_init(void)
 {
 	of_platform_populate(NULL, of_default_bus_match_table, NULL, NULL);
+	coherency_init();
 }
 
 static const char * const armada_370_xp_dt_board_dt_compat[] = {
@@ -60,6 +62,7 @@ static const char * const armada_370_xp_dt_board_dt_compat[] = {
 };
 
 DT_MACHINE_START(ARMADA_XP_DT, "Marvell Aramada 370/XP (Device Tree)")
+	.smp		= smp_ops(armada_xp_smp_ops),
 	.init_machine	= armada_370_xp_dt_init,
 	.map_io		= armada_370_xp_map_io,
 	.init_irq	= armada_370_xp_init_irq,

arch/arm/mach-mvebu/common.h

@@ -20,6 +20,9 @@ void mvebu_restart(char mode, const char *cmd);
 void armada_370_xp_init_irq(void);
 void armada_370_xp_handle_irq(struct pt_regs *regs);
 
+void armada_xp_cpu_die(unsigned int cpu);
 int armada_370_xp_coherency_init(void);
 int armada_370_xp_pmsu_init(void);
+void armada_xp_secondary_startup(void);
+extern struct smp_operations armada_xp_smp_ops;
 #endif

arch/arm/mach-mvebu/headsmp.S

+/*
+ * SMP support: Entry point for secondary CPUs
+ *
+ * Copyright (C) 2012 Marvell
+ *
+ * Yehuda Yitschak <yehuday@marvell.com>
+ * Gregory CLEMENT <gregory.clement@free-electrons.com>
+ * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+ *
+ * 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.
+ *
+ * This file implements the assembly entry point for secondary CPUs in
+ * an SMP kernel. The only thing we need to do is to add the CPU to
+ * the coherency fabric by writing to 2 registers. Currently the base
+ * register addresses are hard coded due to the early initialisation
+ * problems.
+ */
+
+#include <linux/linkage.h>
+#include <linux/init.h>
+
+/*
+ * At this stage the secondary CPUs don't have acces yet to the MMU, so
+ * we have to provide physical addresses
+ */
+#define ARMADA_XP_CFB_BASE	     0xD0020200
+
+	__CPUINIT
+
+/*
+ * Armada XP specific entry point for secondary CPUs.
+ * We add the CPU to the coherency fabric and then jump to secondary
+ * startup
+ */
+ENTRY(armada_xp_secondary_startup)
+
+	/* Read CPU id */
+	mrc     p15, 0, r1, c0, c0, 5
+	and     r1, r1, #0xF
+
+	/* Add CPU to coherency fabric */
+	ldr     r0, =ARMADA_XP_CFB_BASE
+
+	bl	ll_set_cpu_coherent
+	b	secondary_startup
+
+ENDPROC(armada_xp_secondary_startup)

arch/arm/mach-mvebu/hotplug.c

+/*
+ * Symmetric Multi Processing (SMP) support for Armada XP
+ *
+ * Copyright (C) 2012 Marvell
+ *
+ * Lior Amsalem <alior@marvell.com>
+ * Gregory CLEMENT <gregory.clement@free-electrons.com>
+ * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+ *
+ * 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.
+ */
+#include <linux/kernel.h>
+#include <linux/errno.h>
+#include <linux/smp.h>
+#include <asm/proc-fns.h>
+
+/*
+ * platform-specific code to shutdown a CPU
+ *
+ * Called with IRQs disabled
+ */
+void __ref armada_xp_cpu_die(unsigned int cpu)
+{
+	cpu_do_idle();
+
+	/* We should never return from idle */
+	panic("mvebu: cpu %d unexpectedly exit from shutdown\n", cpu);
+}

arch/arm/mach-mvebu/platsmp.c

+/*
+ * Symmetric Multi Processing (SMP) support for Armada XP
+ *
+ * Copyright (C) 2012 Marvell
+ *
+ * Lior Amsalem <alior@marvell.com>
+ * Yehuda Yitschak <yehuday@marvell.com>
+ * Gregory CLEMENT <gregory.clement@free-electrons.com>
+ * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
+ *
+ * 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.
+ *
+ * The Armada XP SoC has 4 ARMv7 PJ4B CPUs running in full HW coherency
+ * This file implements the routines for preparing the SMP infrastructure
+ * and waking up the secondary CPUs
+ */
+
+#include <linux/init.h>
+#include <linux/smp.h>
+#include <linux/clk.h>
+#include <linux/of.h>
+#include <asm/cacheflush.h>
+#include <asm/smp_plat.h>
+#include "common.h"
+#include "armada-370-xp.h"
+#include "pmsu.h"
+#include "coherency.h"
+
+void __init set_secondary_cpus_clock(void)
+{
+	int thiscpu;
+	unsigned long rate;
+	struct clk *cpu_clk = NULL;
+	struct device_node *np = NULL;
+
+	thiscpu = smp_processor_id();
+	for_each_node_by_type(np, "cpu") {
+		int err;
+		int cpu;
+
+		err = of_property_read_u32(np, "reg", &cpu);
+		if (WARN_ON(err))
+			return;
+
+		if (cpu == thiscpu) {
+			cpu_clk = of_clk_get(np, 0);
+			break;
+		}
+	}
+	if (WARN_ON(IS_ERR(cpu_clk)))
+		return;
+	clk_prepare_enable(cpu_clk);
+	rate = clk_get_rate(cpu_clk);
+
+	/* set all the other CPU clk to the same rate than the boot CPU */
+	for_each_node_by_type(np, "cpu") {
+		int err;
+		int cpu;
+
+		err = of_property_read_u32(np, "reg", &cpu);
+		if (WARN_ON(err))
+			return;
+
+		if (cpu != thiscpu) {
+			cpu_clk = of_clk_get(np, 0);
+			clk_set_rate(cpu_clk, rate);
+		}
+	}
+}
+
+static void __cpuinit armada_xp_secondary_init(unsigned int cpu)
+{
+	armada_xp_mpic_smp_cpu_init();
+}
+
+static int __cpuinit armada_xp_boot_secondary(unsigned int cpu,
+					      struct task_struct *idle)
+{
+	pr_info("Booting CPU %d\n", cpu);
+
+	armada_xp_boot_cpu(cpu, armada_xp_secondary_startup);
+
+	return 0;
+}
+
+static void __init armada_xp_smp_init_cpus(void)
+{
+	unsigned int i, ncores;
+	ncores = coherency_get_cpu_count();
+
+	/* Limit possible CPUs to defconfig */
+	if (ncores > nr_cpu_ids) {
+		pr_warn("SMP: %d CPUs physically present. Only %d configured.",
+			ncores, nr_cpu_ids);
+		pr_warn("Clipping CPU count to %d\n", nr_cpu_ids);
+		ncores = nr_cpu_ids;
+	}
+
+	for (i = 0; i < ncores; i++)
+		set_cpu_possible(i, true);
+
+	set_smp_cross_call(armada_mpic_send_doorbell);
+}
+
+void __init armada_xp_smp_prepare_cpus(unsigned int max_cpus)
+{
+	set_secondary_cpus_clock();
+	flush_cache_all();
+	set_cpu_coherent(cpu_logical_map(smp_processor_id()), 0);
+}
+
+struct smp_operations armada_xp_smp_ops __initdata = {
+	.smp_init_cpus		= armada_xp_smp_init_cpus,
+	.smp_prepare_cpus	= armada_xp_smp_prepare_cpus,
+	.smp_secondary_init	= armada_xp_secondary_init,
+	.smp_boot_secondary	= armada_xp_boot_secondary,
+#ifdef CONFIG_HOTPLUG_CPU
+	.cpu_die		= armada_xp_cpu_die,
+#endif
+};