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Subject[PATCH 2/6] x86_64 UV: Use LED to indicate CPU is active
  * Add an idle callback to turn on/off a LED indicating that
the CPU is "active" (ON) or "idle" (OFF).

* Introduces a callback for "post-smp_cpus_done" processing
to setup callback.

Note that this is a RAS feature that allows external monitoring of
various cpu state indicators, not just providing "pretty blinking
lights", as the LED state is readable by the system controller.

Based on linux-2.6.tip/master.

Signed-off-by: Mike Travis <travis@sgi.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
---
arch/x86/kernel/genx2apic_uv_x.c | 40 +++++++++++++++++++++++++++++++++++++++
arch/x86/kernel/smpboot.c | 6 +++++
include/asm-x86/genapic_64.h | 3 ++
3 files changed, 49 insertions(+)

--- linux-2.6.tip.orig/arch/x86/kernel/genx2apic_uv_x.c
+++ linux-2.6.tip/arch/x86/kernel/genx2apic_uv_x.c
@@ -18,6 +18,7 @@
#include <linux/bootmem.h>
#include <linux/module.h>
#include <linux/hardirq.h>
+#include <asm/idle.h>
#include <asm/smp.h>
#include <asm/ipi.h>
#include <asm/genapic.h>
@@ -28,6 +29,8 @@

DEFINE_PER_CPU(int, x2apic_extra_bits);

+static __init void uv_start_system(void);
+
static enum uv_system_type uv_system_type;

static int __init uv_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
@@ -449,6 +452,9 @@ static __init void uv_system_init(void)
map_mmr_high(max_pnode);
map_config_high(max_pnode);
map_mmioh_high(max_pnode);
+
+ /* enable post-smp_cpus_done processing */
+ smp_cpus_done_system = uv_start_system;
}

/*
@@ -466,4 +472,38 @@ void __cpuinit uv_cpu_init(void)
set_x2apic_extra_bits(uv_hub_info->pnode);
}

+/*
+ * Illuminate "activity" LED when CPU is going "active",
+ * extinguish when going "idle".
+ */
+static int uv_idle(struct notifier_block *nfb, unsigned long action, void *junk)
+{
+ if (action == IDLE_START)
+ uv_set_led_bits(0, LED_CPU_ACTIVITY);
+
+ else if (action == IDLE_END)
+ uv_set_led_bits(LED_CPU_ACTIVITY, LED_CPU_ACTIVITY);
+
+ return NOTIFY_OK;
+}
+
+static struct notifier_block uv_idle_notifier = {
+ .notifier_call = uv_idle,
+};

+/*
+ * Initialize idle led callback function
+ */
+static __init void uv_init_led_idle_display(void)
+{
+ /* initialize timer for activity monitor */
+ idle_notifier_register(&uv_idle_notifier);
+}
+
+/*
+ * Initialize subsystems that need to start after the system is up
+ */
+static __init void uv_start_system(void)
+{
+ uv_init_led_idle_display();
+}
--- linux-2.6.tip.orig/arch/x86/kernel/smpboot.c
+++ linux-2.6.tip/arch/x86/kernel/smpboot.c
@@ -1200,6 +1200,9 @@ void __init native_smp_prepare_boot_cpu(
per_cpu(cpu_state, me) = CPU_ONLINE;
}

+/* post-smp_cpus_done processing */
+void (*smp_cpus_done_system)(void);
+
void __init native_smp_cpus_done(unsigned int max_cpus)
{
pr_debug("Boot done.\n");
@@ -1210,6 +1213,9 @@ void __init native_smp_cpus_done(unsigne
setup_ioapic_dest();
#endif
check_nmi_watchdog();
+
+ if (smp_cpus_done_system)
+ smp_cpus_done_system();
}

#ifdef CONFIG_HOTPLUG_CPU
--- linux-2.6.tip.orig/include/asm-x86/genapic_64.h
+++ linux-2.6.tip/include/asm-x86/genapic_64.h
@@ -47,6 +47,9 @@ enum uv_system_type {UV_NONE, UV_LEGACY_
extern enum uv_system_type get_uv_system_type(void);
extern int is_uv_system(void);

+/* system tasks to run after smp_cpus_done */
+extern void (*smp_cpus_done_system)(void);
+
extern struct genapic apic_x2apic_uv_x;
DECLARE_PER_CPU(int, x2apic_extra_bits);
extern void uv_cpu_init(void);
--


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