[PATCH] Assign IRQs to HPET Timers

[Balaji Rao <balajirrao@gmail.com>]

Assign an IRQ to HPET Timer devices when interrupt enable is requested.
This now makes the HPET userspace API work.

drivers/char/hpet.c  |   31 +++++++++++++++++++++++++++++--
include/linux/hpet.h |    2 +-
2 files changed, 30 insertions(+), 3 deletions(-)

Signed-off-by: Balaji Rao R <balajirrao@gmail.com>

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index 4c16778..92bd889 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -390,7 +390,8 @@ static int hpet_ioctl_ieon(struct hpet_dev *devp)
 	struct hpets *hpetp;
 	int irq;
 	unsigned long g, v, t, m;
-	unsigned long flags, isr;
+	unsigned long flags, isr, irq_bitmap;
+	u64 hpet_config;
 
 	timer = devp->hd_timer;
 	hpet = devp->hd_hpet;
@@ -412,7 +413,29 @@ static int hpet_ioctl_ieon(struct hpet_dev *devp)
 		devp->hd_flags |= HPET_SHARED_IRQ;
 	spin_unlock_irq(&hpet_lock);
 
-	irq = devp->hd_hdwirq;
+	/* Assign an IRQ to the timer */
+	hpet_config = readq(&timer->hpet_config);
+	irq_bitmap =
+		(hpet_config & Tn_INT_ROUTE_CAP_MASK) >> Tn_INT_ROUTE_CAP_SHIFT;
+	if (!irq_bitmap)
+		irq = 0;	/* No IRQ Assignable */
+	else {
+		irq = find_first_bit(&irq_bitmap, 32);
+		do {
+			hpet_config |= irq << Tn_INT_ROUTE_CNF_SHIFT;
+			writeq(hpet_config, &timer->hpet_config);
+
+			/* Check whether we wrote a valid IRQ
+			 * number by reading back the field
+			 */
+			hpet_config = readq(&timer->hpet_config);
+			if (irq == (hpet_config & Tn_INT_ROUTE_CNF_MASK)
+					>> Tn_INT_ROUTE_CNF_SHIFT) {
+				devp->hd_hdwirq = irq;
+				break;	/* Success */
+			}
+		} while ((irq = (find_next_bit(&irq_bitmap, 32, irq))));
+	}
 
 	if (irq) {
 		unsigned long irq_flags;
@@ -509,6 +532,10 @@ hpet_ioctl_common(struct hpet_dev *devp, int cmd, unsigned long arg, int kernel)
 			break;
 		v = readq(&timer->hpet_config);
 		v &= ~Tn_INT_ENB_CNF_MASK;
+
+		/* Zero out the IRQ field*/
+		v &= ~Tn_INT_ROUTE_CNF_MASK;
+
 		writeq(v, &timer->hpet_config);
 		if (devp->hd_irq) {
 			free_irq(devp->hd_irq, devp);
diff --git a/include/linux/hpet.h b/include/linux/hpet.h
index 707f7cb..e3c0b2a 100644
--- a/include/linux/hpet.h
+++ b/include/linux/hpet.h
@@ -64,7 +64,7 @@ struct hpet {
  */
 
 #define	Tn_INT_ROUTE_CAP_MASK		(0xffffffff00000000ULL)
-#define	Tn_INI_ROUTE_CAP_SHIFT		(32UL)
+#define	Tn_INT_ROUTE_CAP_SHIFT		(32UL)
 #define	Tn_FSB_INT_DELCAP_MASK		(0x8000UL)
 #define	Tn_FSB_INT_DELCAP_SHIFT		(15)
 #define	Tn_FSB_EN_CNF_MASK		(0x4000UL)