This patch extracts the common code of the cpu hotplug feature across
arm platforms. The goal is to only keep the specific stuff of the
platform in the sub-architecture. I have created a hotplug.c file in
the arm/common directory after studying the cpu hotplug code of
omap2, realview, s5pv310, ux500 and tegra. I have extracted 3 main
platform dependent functions:
-platform_enter_lowpower which prepares the platform for low power.
-platform_do_lowpower on which the cpu will loop until it becomes
really plugged (spurious wake up). This function must returned the cpu
Id in order to leave the unplug state.
-platform_leave_lowpower which restore the platform context.
An ux500 patch is available which uses the common/hotplug.c code.
This patch is quite short because the idle / power down functions are
not yet upstreamed
Signed-off-by: Vincent Guittot <vincent.guittot@xxxxxxxxxxxxxx>
---
arch/arm/Kconfig | 1 +
arch/arm/mach-ux500/Makefile | 2 +-
arch/arm/mach-ux500/hotplug.c | 68 +++++++++-------------------------------
arch/arm/mach-ux500/platsmp.c | 2 +
4 files changed, 20 insertions(+), 53 deletions(-)
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index ca96a44..ee74cf9 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -797,6 +797,7 @@ config ARCH_U8500
select GENERIC_CLOCKEVENTS
select COMMON_CLKDEV
select ARCH_REQUIRE_GPIOLIB
+ select USE_COMMON_ARM_HOTPLUG if HOTPLUG_CPU
help
Support for ST-Ericsson's Ux500 architecture
diff --git a/arch/arm/mach-ux500/Makefile b/arch/arm/mach-ux500/Makefile
index 0612013..cb86197 100644
--- a/arch/arm/mach-ux500/Makefile
+++ b/arch/arm/mach-ux500/Makefile
@@ -8,7 +8,7 @@ obj-$(CONFIG_UX500_SOC_DB8500) += cpu-db8500.o
devices-db8500.o prcmu.o
obj-$(CONFIG_MACH_U8500_MOP) += board-mop500.o board-mop500-sdi.o
obj-$(CONFIG_MACH_U5500) += board-u5500.o
obj-$(CONFIG_SMP) += platsmp.o headsmp.o
-obj-$(CONFIG_HOTPLUG_CPU) += hotplug.o
+obj-$(CONFIG_USE_COMMON_ARM_HOTPLUG) += hotplug.o
obj-$(CONFIG_LOCAL_TIMERS) += localtimer.o
obj-$(CONFIG_REGULATOR_AB8500) += board-mop500-regulators.o
obj-$(CONFIG_U5500_MODEM_IRQ) += modem_irq.o
diff --git a/arch/arm/mach-ux500/hotplug.c b/arch/arm/mach-ux500/hotplug.c
index b782a03..14a614f 100644
--- a/arch/arm/mach-ux500/hotplug.c
+++ b/arch/arm/mach-ux500/hotplug.c
@@ -6,70 +6,34 @@
* Based on ARM realview platform
*
* Author: Sundar Iyer <sundar.iyer@xxxxxxxxxxxxxx>
+ * Author: Vincent Guittot <vincent.guittot@xxxxxxxxxxxxxx>
*
+ * We only keep platform related code in the subarchitecture directory.
+ * The common code across platform has been moved into kernel/common directory
*/
-#include <linux/kernel.h>
-#include <linux/errno.h>
-#include <linux/smp.h>
-#include <linux/completion.h>
-#include <asm/cacheflush.h>
+#include <asm/hotplug.h>
extern volatile int pen_release;
-static DECLARE_COMPLETION(cpu_killed);
-
-static inline void platform_do_lowpower(unsigned int cpu)
-{
- flush_cache_all();
-
- /* we put the platform to just WFI */
- for (;;) {
- __asm__ __volatile__("dsb\n\t" "wfi\n\t"
- : : : "memory");
- if (pen_release == cpu) {
- /*
- * OK, proper wakeup, we're done
- */
- break;
- }
- }
-}
-
-int platform_cpu_kill(unsigned int cpu)
+/* Default implementation that will be used if not override
+ * by power specific implementation
+ */
+void __attribute__((weak)) platform_enter_lowpower(unsigned int cpu)
{
- return wait_for_completion_timeout(&cpu_killed, 5000);
+ return;
}
-/*
- * platform-specific code to shutdown a CPU
- *
- * Called with IRQs disabled
- */
-void platform_cpu_die(unsigned int cpu)
+int __attribute__((weak)) platform_do_lowpower(unsigned int cpu)
{
-#ifdef DEBUG
- unsigned int this_cpu = hard_smp_processor_id();
-
- if (cpu != this_cpu) {
- printk(KERN_CRIT "Eek! platform_cpu_die running on %u, should be %u\n",
- this_cpu, cpu);
- BUG();
- }
-#endif
-
- printk(KERN_NOTICE "CPU%u: shutdown\n", cpu);
- complete(&cpu_killed);
+ __asm__ __volatile__("dsb\n\t" "wfi\n\t"
+ : : : "memory");
- /* directly enter low power state, skipping secure registers */
- platform_do_lowpower(cpu);
+ return pen_release;
}
-int platform_cpu_disable(unsigned int cpu)
+void __attribute__((weak)) platform_leave_lowpower(unsigned int cpu)
{
- /*
- * we don't allow CPU 0 to be shutdown (it is still too special
- * e.g. clock tick interrupts)
- */
- return cpu == 0 ? -EPERM : 0;
+ return;
}
+
diff --git a/arch/arm/mach-ux500/platsmp.c b/arch/arm/mach-ux500/platsmp.c
index 9e4c678..3074260 100644
--- a/arch/arm/mach-ux500/platsmp.c
+++ b/arch/arm/mach-ux500/platsmp.c
@@ -51,6 +51,7 @@ void __cpuinit platform_secondary_init(unsigned int cpu)
* pen, then head off into the C entry point
*/
pen_release = -1;
+ smp_wmb();
/*
* Synchronise with the boot thread.
@@ -82,6 +83,7 @@ int __cpuinit boot_secondary(unsigned int cpu,
struct task_struct *idle)
timeout = jiffies + (1 * HZ);
while (time_before(jiffies, timeout)) {
+ smp_rmb();
if (pen_release == -1)
break;
}
--
1.7.0.4
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