[IA64] SN: Add support for CPU disable

Add additional support for CPU disable on SN platforms.
Correctly setup the smp_affinity mask for I/O error IRQs.
Restrict the use of the feature to Altix 4000 and 450 systems
running with a CPU disable capable PROM, and do not allow disabling
of CPU 0.

Signed-off-by: John Keller <jpk@sgi.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>

3 files changed, 51 insertions, 4 deletions

diff --git a/arch/ia64/sn/kernel/huberror.c b/arch/ia64/sn/kernel/huberror.c
index 2c3f9dfca78b..b663168da55c 100644
--- a/arch/ia64/sn/kernel/huberror.c
+++ b/arch/ia64/sn/kernel/huberror.c
@@ -185,11 +185,14 @@ void hubiio_crb_error_handler(struct hubdev_info *hubdev_info)
  */
 void hub_error_init(struct hubdev_info *hubdev_info)
 {
+
         if (request_irq(SGI_II_ERROR, hub_eint_handler, IRQF_SHARED,
-                        "SN_hub_error", (void *)hubdev_info))
+                        "SN_hub_error", (void *)hubdev_info)) {
                 printk("hub_error_init: Failed to request_irq for 0x%p\n",
                     hubdev_info);
-        return;
+                return;
+        }
+        sn_set_err_irq_affinity(SGI_II_ERROR);
 }
 
 
@@ -202,11 +205,14 @@ void hub_error_init(struct hubdev_info *hubdev_info)
  */
 void ice_error_init(struct hubdev_info *hubdev_info)
 {
+
         if (request_irq
             (SGI_TIO_ERROR, (void *)hub_eint_handler, IRQF_SHARED, "SN_TIO_error",
-             (void *)hubdev_info))
+             (void *)hubdev_info)) {
                 printk("ice_error_init: request_irq() error hubdev_info 0x%p\n",
                        hubdev_info);
-        return;
+                return;
+        }
+        sn_set_err_irq_affinity(SGI_TIO_ERROR);
 }
 
diff --git a/arch/ia64/sn/kernel/irq.c b/arch/ia64/sn/kernel/irq.c
index 360047389449..0f9b12683bf3 100644
--- a/arch/ia64/sn/kernel/irq.c
+++ b/arch/ia64/sn/kernel/irq.c
@@ -19,6 +19,7 @@
 #include <asm/sn/pcidev.h>
 #include <asm/sn/shub_mmr.h>
 #include <asm/sn/sn_sal.h>
+#include <asm/sn/sn_feature_sets.h>
 
 static void force_interrupt(int irq);
 static void register_intr_pda(struct sn_irq_info *sn_irq_info);
@@ -233,6 +234,20 @@ static void sn_set_affinity_irq(unsigned int irq, cpumask_t mask)
                 (void)sn_retarget_vector(sn_irq_info, nasid, slice);
 }
 
+#ifdef CONFIG_SMP
+void sn_set_err_irq_affinity(unsigned int irq)
+{
+        /*
+         * On systems which support CPU disabling (SHub2), all error interrupts
+         * are targetted at the boot CPU.
+         */
+        if (is_shub2() && sn_prom_feature_available(PRF_CPU_DISABLE_SUPPORT))
+                set_irq_affinity_info(irq, cpu_physical_id(0), 0);
+}
+#else
+void sn_set_err_irq_affinity(unsigned int irq) { }
+#endif
+
 static void
 sn_mask_irq(unsigned int irq)
 {
diff --git a/arch/ia64/sn/kernel/sn2/sn2_smp.c b/arch/ia64/sn/kernel/sn2/sn2_smp.c
index 033c8a9f000e..f3c69329e145 100644
--- a/arch/ia64/sn/kernel/sn2/sn2_smp.c
+++ b/arch/ia64/sn/kernel/sn2/sn2_smp.c
@@ -40,6 +40,7 @@
 #include <asm/sn/shub_mmr.h>
 #include <asm/sn/nodepda.h>
 #include <asm/sn/rw_mmr.h>
+#include <asm/sn/sn_feature_sets.h>
 
 DEFINE_PER_CPU(struct ptc_stats, ptcstats);
 DECLARE_PER_CPU(struct ptc_stats, ptcstats);
@@ -429,6 +430,31 @@ void sn2_send_IPI(int cpuid, int vector, int delivery_mode, int redirect)
         sn_send_IPI_phys(nasid, physid, vector, delivery_mode);
 }
 
+#ifdef CONFIG_HOTPLUG_CPU
+/**
+ * sn_cpu_disable_allowed - Determine if a CPU can be disabled.
+ * @cpu - CPU that is requested to be disabled.
+ *
+ * CPU disable is only allowed on SHub2 systems running with a PROM
+ * that supports CPU disable. It is not permitted to disable the boot processor.
+ */
+bool sn_cpu_disable_allowed(int cpu)
+{
+        if (is_shub2() && sn_prom_feature_available(PRF_CPU_DISABLE_SUPPORT)) {
+                if (cpu != 0)
+                        return true;
+                else
+                        printk(KERN_WARNING
+                              "Disabling the boot processor is not allowed.\n");
+
+        } else
+                printk(KERN_WARNING
+                       "CPU disable is not supported on this system.\n");
+
+        return false;
+}
+#endif /* CONFIG_HOTPLUG_CPU */
+
 #ifdef CONFIG_PROC_FS
 
 #define PTC_BASENAME    "sgi_sn/ptc_statistics"