[Qemu-devel] [PATCH 1/7] s390/airq: add support for irq ranges

[Cornelia Huck]

From: Martin Schwidefsky <address@hidden>

Add airq_iv_alloc and airq_iv_free to allocate and free consecutive
ranges of irqs from the interrupt vector.

Signed-off-by: Martin Schwidefsky <address@hidden>
Signed-off-by: Cornelia Huck <address@hidden>
---
 arch/s390/include/asm/airq.h |   14 +++++++--
 drivers/s390/cio/airq.c      |   66 ++++++++++++++++++++++++++----------------
 2 files changed, 53 insertions(+), 27 deletions(-)

diff --git a/arch/s390/include/asm/airq.h b/arch/s390/include/asm/airq.h
index 4bbb595..bd93ff6 100644
--- a/arch/s390/include/asm/airq.h
+++ b/arch/s390/include/asm/airq.h
@@ -44,11 +44,21 @@ struct airq_iv {
 
 struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags);
 void airq_iv_release(struct airq_iv *iv);
-unsigned long airq_iv_alloc_bit(struct airq_iv *iv);
-void airq_iv_free_bit(struct airq_iv *iv, unsigned long bit);
+unsigned long airq_iv_alloc(struct airq_iv *iv, unsigned long num);
+void airq_iv_free(struct airq_iv *iv, unsigned long bit, unsigned long num);
 unsigned long airq_iv_scan(struct airq_iv *iv, unsigned long start,
                           unsigned long end);
 
+static inline unsigned long airq_iv_alloc_bit(struct airq_iv *iv)
+{
+       return airq_iv_alloc(iv, 1);
+}
+
+static inline void airq_iv_free_bit(struct airq_iv *iv, unsigned long bit)
+{
+       airq_iv_free(iv, bit, 1);
+}
+
 static inline unsigned long airq_iv_end(struct airq_iv *iv)
 {
        return iv->end;
diff --git a/drivers/s390/cio/airq.c b/drivers/s390/cio/airq.c
index f055df0..445564c 100644
--- a/drivers/s390/cio/airq.c
+++ b/drivers/s390/cio/airq.c
@@ -186,55 +186,71 @@ void airq_iv_release(struct airq_iv *iv)
 EXPORT_SYMBOL(airq_iv_release);
 
 /**
- * airq_iv_alloc_bit - allocate an irq bit from an interrupt vector
+ * airq_iv_alloc - allocate irq bits from an interrupt vector
  * @iv: pointer to an interrupt vector structure
+ * @num: number of consecutive irq bits to allocate
  *
- * Returns the bit number of the allocated irq, or -1UL if no bit
- * is available or the AIRQ_IV_ALLOC flag has not been specified
+ * Returns the bit number of the first irq in the allocated block of irqs,
+ * or -1UL if no bit is available or the AIRQ_IV_ALLOC flag has not been
+ * specified
  */
-unsigned long airq_iv_alloc_bit(struct airq_iv *iv)
+unsigned long airq_iv_alloc(struct airq_iv *iv, unsigned long num)
 {
-       unsigned long bit;
+       unsigned long bit, i;
 
-       if (!iv->avail)
+       if (!iv->avail || num == 0)
                return -1UL;
        spin_lock(&iv->lock);
        bit = find_first_bit_inv(iv->avail, iv->bits);
-       if (bit < iv->bits) {
-               clear_bit_inv(bit, iv->avail);
-               if (bit >= iv->end)
-                       iv->end = bit + 1;
-       } else
+       while (bit + num <= iv->bits) {
+               for (i = 1; i < num; i++)
+                       if (!test_bit_inv(bit + i, iv->avail))
+                               break;
+               if (i >= num) {
+                       /* Found a suitable block of irqs */
+                       for (i = 0; i < num; i++)
+                               clear_bit_inv(bit + i, iv->avail);
+                       if (bit + num >= iv->end)
+                               iv->end = bit + num + 1;
+                       break;
+               }
+               bit = find_next_bit_inv(iv->avail, iv->bits, bit + i + 1);
+       }
+       if (bit + num > iv->bits)
                bit = -1UL;
        spin_unlock(&iv->lock);
        return bit;
 
 }
-EXPORT_SYMBOL(airq_iv_alloc_bit);
+EXPORT_SYMBOL(airq_iv_alloc);
 
 /**
- * airq_iv_free_bit - free an irq bit of an interrupt vector
+ * airq_iv_free - free irq bits of an interrupt vector
  * @iv: pointer to interrupt vector structure
- * @bit: number of the irq bit to free
+ * @bit: number of the first irq bit to free
+ * @num: number of consecutive irq bits to free
  */
-void airq_iv_free_bit(struct airq_iv *iv, unsigned long bit)
+void airq_iv_free(struct airq_iv *iv, unsigned long bit, unsigned long num)
 {
-       if (!iv->avail)
+       unsigned long i;
+
+       if (!iv->avail || num == 0)
                return;
        spin_lock(&iv->lock);
-       /* Clear (possibly left over) interrupt bit */
-       clear_bit_inv(bit, iv->vector);
-       /* Make the bit position available again */
-       set_bit_inv(bit, iv->avail);
-       if (bit == iv->end - 1) {
+       for (i = 0; i < num; i++) {
+               /* Clear (possibly left over) interrupt bit */
+               clear_bit_inv(bit + i, iv->vector);
+               /* Make the bit positions available again */
+               set_bit_inv(bit + i, iv->avail);
+       }
+       if (bit + num >= iv->end) {
                /* Find new end of bit-field */
-               while (--iv->end > 0)
-                       if (!test_bit_inv(iv->end - 1, iv->avail))
-                               break;
+               while (iv->end > 0 && !test_bit_inv(iv->end - 1, iv->avail))
+                       iv->end--;
        }
        spin_unlock(&iv->lock);
 }
-EXPORT_SYMBOL(airq_iv_free_bit);
+EXPORT_SYMBOL(airq_iv_free);
 
 /**
  * airq_iv_scan - scan interrupt vector for non-zero bits
-- 
1.7.9.5