IB/qib: Add DCA support

This patch adds DCA cache warming for systems that support DCA.

The code uses cpu affinity notification to react to an affinity change
from a user mode program like irqbalance and (re-)program the chip
accordingly. This notification avoids reading the current cpu on every
interrupt.

Reviewed-by: Dean Luick <dean.luick@intel.com>
Signed-off-by: Mike Marciniszyn <mike.marciniszyn@intel.com>

[ Add Kconfig dependency on SMP && GENERIC_HARDIRQS to avoid failure to
  build due to undefined struct irq_affinity_notify.  - Roland ]

Signed-off-by: Roland Dreier <roland@purestorage.com>

drivers/infiniband/hw/qib/qib.h

@@ -428,9 +428,19 @@ struct qib_verbs_txreq {
 #define ACTIVITY_TIMER 5
 
 #define MAX_NAME_SIZE 64
+
+#ifdef CONFIG_INFINIBAND_QIB_DCA
+struct qib_irq_notify;
+#endif
+
 struct qib_msix_entry {
 	struct msix_entry msix;
 	void *arg;
+#ifdef CONFIG_INFINIBAND_QIB_DCA
+	int dca;
+	int rcv;
+	struct qib_irq_notify *notifier;
+#endif
 	char name[MAX_NAME_SIZE];
 	cpumask_var_t mask;
 };
@@ -828,6 +838,9 @@ struct qib_devdata {
 		struct qib_ctxtdata *);
 	void (*f_writescratch)(struct qib_devdata *, u32);
 	int (*f_tempsense_rd)(struct qib_devdata *, int regnum);
+#ifdef CONFIG_INFINIBAND_QIB_DCA
+	int (*f_notify_dca)(struct qib_devdata *, unsigned long event);
+#endif
 
 	char *boardname; /* human readable board info */