x86: assign IRQs to HPET timers

The userspace API for the HPET (see Documentation/hpet.txt) did not work. The
HPET_IE_ON ioctl was failing as there was no IRQ assigned to the timer
device. This patch fixes it by allocating IRQs to timer blocks in the HPET.

arch/x86/kernel/hpet.c |   13 +++++--------
drivers/char/hpet.c    |   45 ++++++++++++++++++++++++++++++++++++++-------
include/linux/hpet.h   |    2 +-
3 files changed, 44 insertions(+), 16 deletions(-)

Signed-off-by: Balaji Rao <balajirrao@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

1 files changed, 38 insertions, 7 deletions

diff --git a/drivers/char/hpet.c b/drivers/char/hpet.c
index 4c16778e3f84..593b32cfbc33 100644
--- a/drivers/char/hpet.c
+++ b/drivers/char/hpet.c
@@ -806,14 +806,14 @@ static unsigned long hpet_calibrate(struct hpets *hpetp)
 
 int hpet_alloc(struct hpet_data *hdp)
 {
-        u64 cap, mcfg;
+        u64 cap, mcfg, hpet_config;
         struct hpet_dev *devp;
-        u32 i, ntimer;
+        u32 i, ntimer, irq;
         struct hpets *hpetp;
         size_t siz;
         struct hpet __iomem *hpet;
         static struct hpets *last = NULL;
-        unsigned long period;
+        unsigned long period, irq_bitmap;
         unsigned long long temp;
 
         /*
@@ -840,11 +840,41 @@ int hpet_alloc(struct hpet_data *hdp)
         hpetp->hp_hpet_phys = hdp->hd_phys_address;
 
         hpetp->hp_ntimer = hdp->hd_nirqs;
+        hpet = hpetp->hp_hpet;
 
-        for (i = 0; i < hdp->hd_nirqs; i++)
-                hpetp->hp_dev[i].hd_hdwirq = hdp->hd_irq[i];
+        /* Assign IRQs statically for legacy devices */
+        hpetp->hp_dev[0].hd_hdwirq = hdp->hd_irq[0];
+        hpetp->hp_dev[1].hd_hdwirq = hdp->hd_irq[1];
 
-        hpet = hpetp->hp_hpet;
+        /* Assign IRQs dynamically for the others */
+        for (i = 2, devp = &hpetp->hp_dev[2]; i < hdp->hd_nirqs; i++, devp++) {
+                struct hpet_timer __iomem *timer;
+
+                timer = &hpet->hpet_timers[devp - hpetp->hp_dev];
+
+                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 valid 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);
+
+                                /*
+                                 * Verify whether we have written a valid
+                                 * IRQ number by reading it back again
+                                 */
+                                hpet_config = readq(&timer->hpet_config);
+                                if (irq == (hpet_config & Tn_INT_ROUTE_CNF_MASK)
+                                                >> Tn_INT_ROUTE_CNF_SHIFT)
+                                        break;  /* Success */
+                        } while ((irq = (find_next_bit(&irq_bitmap, 32, irq))));
+                }
+                hpetp->hp_dev[i].hd_hdwirq = irq;
+        }
 
         cap = readq(&hpet->hpet_cap);
 
@@ -875,7 +905,8 @@ int hpet_alloc(struct hpet_data *hdp)
                 hpetp->hp_which, hdp->hd_phys_address,
                 hpetp->hp_ntimer > 1 ? "s" : "");
         for (i = 0; i < hpetp->hp_ntimer; i++)
-                printk("%s %d", i > 0 ? "," : "", hdp->hd_irq[i]);
+                printk("%s %d", i > 0 ? "," : "",
+                                hpetp->hp_dev[i].hd_hdwirq);
         printk("\n");
 
         printk(KERN_INFO "hpet%u: %u %d-bit timers, %Lu Hz\n",