arm: introduce psci_smp_ops

Rename virt_smp_ops to psci_smp_ops and move them to arch/arm/kernel/psci_smp.c.
Remove mach-virt/platsmp.c, now unused.
Compile psci_smp if CONFIG_ARM_PSCI and CONFIG_SMP.

Add a cpu_die smp_op based on psci_ops.cpu_off.

Initialize PSCI before setting smp_ops in setup_arch.

If PSCI is available on the platform, prefer psci_smp_ops over the
platform smp_ops.
Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Acked-by: Will Deacon <will.deacon@arm.com>
CC: arnd@arndb.de
CC: marc.zyngier@arm.com
CC: linux@arm.linux.org.uk
CC: nico@linaro.org
CC: rob.herring@calxeda.com

arch/arm/include/asm/psci.h

@@ -32,5 +32,14 @@ struct psci_operations {
 };
 
 extern struct psci_operations psci_ops;
+extern struct smp_operations psci_smp_ops;
+
+#ifdef CONFIG_ARM_PSCI
+void psci_init(void);
+bool psci_smp_available(void);
+#else
+static inline void psci_init(void) { }
+static inline bool psci_smp_available(void) { return false; }
+#endif
 
 #endif /* __ASM_ARM_PSCI_H */

arch/arm/kernel/Makefile

@@ -82,6 +82,9 @@ obj-$(CONFIG_DEBUG_LL)	+= debug.o
 obj-$(CONFIG_EARLY_PRINTK)	+= early_printk.o
 
 obj-$(CONFIG_ARM_VIRT_EXT)	+= hyp-stub.o
-obj-$(CONFIG_ARM_PSCI)		+= psci.o
+ifeq ($(CONFIG_ARM_PSCI),y)
+obj-y				+= psci.o
+obj-$(CONFIG_SMP)		+= psci_smp.o
+endif
 
 extra-y := $(head-y) vmlinux.lds

arch/arm/kernel/psci.c

@@ -158,7 +158,7 @@ static const struct of_device_id psci_of_match[] __initconst = {
 	{},
 };
 
-static int __init psci_init(void)
+void __init psci_init(void)
 {
 	struct device_node *np;
 	const char *method;
@@ -166,7 +166,7 @@ static int __init psci_init(void)
 
 	np = of_find_matching_node(NULL, psci_of_match);
 	if (!np)
-		return 0;
+		return;
 
 	pr_info("probing function IDs from device-tree\n");
 
@@ -206,6 +206,5 @@ static int __init psci_init(void)
 
 out_put_node:
 	of_node_put(np);
-	return 0;
+	return;
 }
-early_initcall(psci_init);

arch/arm/mach-virt/platsmp.c → arch/arm/kernel/psci_smp.c

 /*
- * Dummy Virtual Machine - does what it says on the tin.
- *
- * Copyright (C) 2012 ARM Ltd
- * Author: Will Deacon <will.deacon@arm.com>
- *
  * 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.
@@ -13,38 +8,77 @@
  * 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, see <http://www.gnu.org/licenses/>.
+ * Copyright (C) 2012 ARM Limited
+ *
+ * Author: Will Deacon <will.deacon@arm.com>
  */
 
 #include <linux/init.h>
+#include <linux/irqchip/arm-gic.h>
 #include <linux/smp.h>
 #include <linux/of.h>
 
 #include <asm/psci.h>
 #include <asm/smp_plat.h>
 
+/*
+ * psci_smp assumes that the following is true about PSCI:
+ *
+ * cpu_suspend   Suspend the execution on a CPU
+ * @state        we don't currently describe affinity levels, so just pass 0.
+ * @entry_point  the first instruction to be executed on return
+ * returns 0  success, < 0 on failure
+ *
+ * cpu_off       Power down a CPU
+ * @state        we don't currently describe affinity levels, so just pass 0.
+ * no return on successful call
+ *
+ * cpu_on        Power up a CPU
+ * @cpuid        cpuid of target CPU, as from MPIDR
+ * @entry_point  the first instruction to be executed on return
+ * returns 0  success, < 0 on failure
+ *
+ * migrate       Migrate the context to a different CPU
+ * @cpuid        cpuid of target CPU, as from MPIDR
+ * returns 0  success, < 0 on failure
+ *
+ */
+
 extern void secondary_startup(void);
 
-static void __init virt_smp_init_cpus(void)
+static int __cpuinit psci_boot_secondary(unsigned int cpu,
+					 struct task_struct *idle)
 {
+	if (psci_ops.cpu_on)
+		return psci_ops.cpu_on(cpu_logical_map(cpu),
+				       __pa(secondary_startup));
+	return -ENODEV;
 }
 
-static void __init virt_smp_prepare_cpus(unsigned int max_cpus)
+#ifdef CONFIG_HOTPLUG_CPU
+void __ref psci_cpu_die(unsigned int cpu)
 {
+       const struct psci_power_state ps = {
+               .type = PSCI_POWER_STATE_TYPE_POWER_DOWN,
+       };
+
+       if (psci_ops.cpu_off)
+               psci_ops.cpu_off(ps);
+
+       /* We should never return */
+       panic("psci: cpu %d failed to shutdown\n", cpu);
 }
+#else
+#define psci_cpu_die NULL
+#endif
 
-static int __cpuinit virt_boot_secondary(unsigned int cpu,
-					 struct task_struct *idle)
+bool __init psci_smp_available(void)
 {
-	if (psci_ops.cpu_on)
-		return psci_ops.cpu_on(cpu_logical_map(cpu),
-				       __pa(secondary_startup));
-	return -ENODEV;
+	/* is cpu_on available at least? */
+	return (psci_ops.cpu_on != NULL);
 }
 
-struct smp_operations __initdata virt_smp_ops = {
-	.smp_init_cpus		= virt_smp_init_cpus,
-	.smp_prepare_cpus	= virt_smp_prepare_cpus,
-	.smp_boot_secondary	= virt_boot_secondary,
+struct smp_operations __initdata psci_smp_ops = {
+	.smp_boot_secondary	= psci_boot_secondary,
+	.cpu_die		= psci_cpu_die,
 };

arch/arm/kernel/setup.c

@@ -37,6 +37,7 @@
 #include <asm/cputype.h>
 #include <asm/elf.h>
 #include <asm/procinfo.h>
+#include <asm/psci.h>
 #include <asm/sections.h>
 #include <asm/setup.h>
 #include <asm/smp_plat.h>
@@ -796,9 +797,13 @@ void __init setup_arch(char **cmdline_p)
 	unflatten_device_tree();
 
 	arm_dt_init_cpu_maps();
+	psci_init();
 #ifdef CONFIG_SMP
 	if (is_smp()) {
-		smp_set_ops(mdesc->smp);
+		if (psci_smp_available())
+			smp_set_ops(&psci_smp_ops);
+		else if (mdesc->smp)
+			smp_set_ops(mdesc->smp);
 		smp_init_cpus();
 	}
 #endif

arch/arm/mach-virt/Makefile

@@ -3,4 +3,3 @@
 #
 
 obj-y					:= virt.o
-obj-$(CONFIG_SMP)			+= platsmp.o

arch/arm/mach-virt/virt.c

@@ -36,11 +36,8 @@ static const char *virt_dt_match[] = {
 	NULL
 };
 
-extern struct smp_operations virt_smp_ops;
-
 DT_MACHINE_START(VIRT, "Dummy Virtual Machine")
 	.init_irq	= irqchip_init,
 	.init_machine	= virt_init,
-	.smp		= smp_ops(virt_smp_ops),
 	.dt_compat	= virt_dt_match,
 MACHINE_END