s390/airq: introduce adapter interrupt vector helper

The PCI code is the first user of adapter interrupts vectors.
Add a set of helpers to airq.c to separate the adatper interrupt
code from the PCI bits. The helpers allow for adapter interrupt
vectors of any size.

Reviewed-by: Sebastian Ott <sebott@linux.vnet.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

2 files changed, 220 insertions, 0 deletions

diff --git a/arch/s390/include/asm/airq.h b/arch/s390/include/asm/airq.h
index 4066cee0c2d2..4bbb5957ed1b 100644
--- a/arch/s390/include/asm/airq.h
+++ b/arch/s390/include/asm/airq.h
@@ -9,6 +9,8 @@
 #ifndef _ASM_S390_AIRQ_H
 #define _ASM_S390_AIRQ_H
 
+#include <linux/bit_spinlock.h>
+
 struct airq_struct {
 	struct hlist_node list;		/* Handler queueing. */
 	void (*handler)(struct airq_struct *);	/* Thin-interrupt handler */
@@ -23,4 +25,69 @@ struct airq_struct {
 int register_adapter_interrupt(struct airq_struct *airq);
 void unregister_adapter_interrupt(struct airq_struct *airq);
 
+/* Adapter interrupt bit vector */
+struct airq_iv {
+	unsigned long *vector;	/* Adapter interrupt bit vector */
+	unsigned long *avail;	/* Allocation bit mask for the bit vector */
+	unsigned long *bitlock;	/* Lock bit mask for the bit vector */
+	unsigned long *ptr;	/* Pointer associated with each bit */
+	unsigned int *data;	/* 32 bit value associated with each bit */
+	unsigned long bits;	/* Number of bits in the vector */
+	unsigned long end;	/* Number of highest allocated bit + 1 */
+	spinlock_t lock;	/* Lock to protect alloc & free */
+};
+
+#define AIRQ_IV_ALLOC	1	/* Use an allocation bit mask */
+#define AIRQ_IV_BITLOCK	2	/* Allocate the lock bit mask */
+#define AIRQ_IV_PTR	4	/* Allocate the ptr array */
+#define AIRQ_IV_DATA	8	/* Allocate the data array */
+
+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_scan(struct airq_iv *iv, unsigned long start,
+			   unsigned long end);
+
+static inline unsigned long airq_iv_end(struct airq_iv *iv)
+{
+	return iv->end;
+}
+
+static inline void airq_iv_lock(struct airq_iv *iv, unsigned long bit)
+{
+	const unsigned long be_to_le = BITS_PER_LONG - 1;
+	bit_spin_lock(bit ^ be_to_le, iv->bitlock);
+}
+
+static inline void airq_iv_unlock(struct airq_iv *iv, unsigned long bit)
+{
+	const unsigned long be_to_le = BITS_PER_LONG - 1;
+	bit_spin_unlock(bit ^ be_to_le, iv->bitlock);
+}
+
+static inline void airq_iv_set_data(struct airq_iv *iv, unsigned long bit,
+				    unsigned int data)
+{
+	iv->data[bit] = data;
+}
+
+static inline unsigned int airq_iv_get_data(struct airq_iv *iv,
+					    unsigned long bit)
+{
+	return iv->data[bit];
+}
+
+static inline void airq_iv_set_ptr(struct airq_iv *iv, unsigned long bit,
+				   unsigned long ptr)
+{
+	iv->ptr[bit] = ptr;
+}
+
+static inline unsigned long airq_iv_get_ptr(struct airq_iv *iv,
+					    unsigned long bit)
+{
+	return iv->ptr[bit];
+}
+
 #endif /* _ASM_S390_AIRQ_H */
diff --git a/drivers/s390/cio/airq.c b/drivers/s390/cio/airq.c
index 91edbd7ee806..6ead6d076445 100644
--- a/drivers/s390/cio/airq.c
+++ b/drivers/s390/cio/airq.c
@@ -93,3 +93,156 @@ void do_adapter_IO(u8 isc)
 			airq->handler(airq);
 	rcu_read_unlock();
 }
+
+/**
+ * airq_iv_create - create an interrupt vector
+ * @bits: number of bits in the interrupt vector
+ * @flags: allocation flags
+ *
+ * Returns a pointer to an interrupt vector structure
+ */
+struct airq_iv *airq_iv_create(unsigned long bits, unsigned long flags)
+{
+	struct airq_iv *iv;
+	unsigned long size;
+
+	iv = kzalloc(sizeof(*iv), GFP_KERNEL);
+	if (!iv)
+		goto out;
+	iv->bits = bits;
+	size = BITS_TO_LONGS(bits) * sizeof(unsigned long);
+	iv->vector = kzalloc(size, GFP_KERNEL);
+	if (!iv->vector)
+		goto out_free;
+	if (flags & AIRQ_IV_ALLOC) {
+		iv->avail = kmalloc(size, GFP_KERNEL);
+		if (!iv->avail)
+			goto out_free;
+		memset(iv->avail, 0xff, size);
+		iv->end = 0;
+	} else
+		iv->end = bits;
+	if (flags & AIRQ_IV_BITLOCK) {
+		iv->bitlock = kzalloc(size, GFP_KERNEL);
+		if (!iv->bitlock)
+			goto out_free;
+	}
+	if (flags & AIRQ_IV_PTR) {
+		size = bits * sizeof(unsigned long);
+		iv->ptr = kzalloc(size, GFP_KERNEL);
+		if (!iv->ptr)
+			goto out_free;
+	}
+	if (flags & AIRQ_IV_DATA) {
+		size = bits * sizeof(unsigned int);
+		iv->data = kzalloc(size, GFP_KERNEL);
+		if (!iv->data)
+			goto out_free;
+	}
+	spin_lock_init(&iv->lock);
+	return iv;
+
+out_free:
+	kfree(iv->ptr);
+	kfree(iv->bitlock);
+	kfree(iv->avail);
+	kfree(iv->vector);
+	kfree(iv);
+out:
+	return NULL;
+}
+EXPORT_SYMBOL(airq_iv_create);
+
+/**
+ * airq_iv_release - release an interrupt vector
+ * @iv: pointer to interrupt vector structure
+ */
+void airq_iv_release(struct airq_iv *iv)
+{
+	kfree(iv->data);
+	kfree(iv->ptr);
+	kfree(iv->bitlock);
+	kfree(iv->vector);
+	kfree(iv->avail);
+	kfree(iv);
+}
+EXPORT_SYMBOL(airq_iv_release);
+
+/**
+ * airq_iv_alloc_bit - allocate an irq bit from an interrupt vector
+ * @iv: pointer to an interrupt vector structure
+ *
+ * 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
+ */
+unsigned long airq_iv_alloc_bit(struct airq_iv *iv)
+{
+	const unsigned long be_to_le = BITS_PER_LONG - 1;
+	unsigned long bit;
+
+	if (!iv->avail)
+		return -1UL;
+	spin_lock(&iv->lock);
+	bit = find_first_bit_left(iv->avail, iv->bits);
+	if (bit < iv->bits) {
+		clear_bit(bit ^ be_to_le, iv->avail);
+		if (bit >= iv->end)
+			iv->end = bit + 1;
+	} else
+		bit = -1UL;
+	spin_unlock(&iv->lock);
+	return bit;
+
+}
+EXPORT_SYMBOL(airq_iv_alloc_bit);
+
+/**
+ * airq_iv_free_bit - free an irq bit of an interrupt vector
+ * @iv: pointer to interrupt vector structure
+ * @bit: number of the irq bit to free
+ */
+void airq_iv_free_bit(struct airq_iv *iv, unsigned long bit)
+{
+	const unsigned long be_to_le = BITS_PER_LONG - 1;
+
+	if (!iv->avail)
+		return;
+	spin_lock(&iv->lock);
+	/* Clear (possibly left over) interrupt bit */
+	clear_bit(bit ^ be_to_le, iv->vector);
+	/* Make the bit position available again */
+	set_bit(bit ^ be_to_le, iv->avail);
+	if (bit == iv->end - 1) {
+		/* Find new end of bit-field */
+		while (--iv->end > 0)
+			if (!test_bit((iv->end - 1) ^ be_to_le, iv->avail))
+				break;
+	}
+	spin_unlock(&iv->lock);
+}
+EXPORT_SYMBOL(airq_iv_free_bit);
+
+/**
+ * airq_iv_scan - scan interrupt vector for non-zero bits
+ * @iv: pointer to interrupt vector structure
+ * @start: bit number to start the search
+ * @end: bit number to end the search
+ *
+ * Returns the bit number of the next non-zero interrupt bit, or
+ * -1UL if the scan completed without finding any more any non-zero bits.
+ */
+unsigned long airq_iv_scan(struct airq_iv *iv, unsigned long start,
+			   unsigned long end)
+{
+	const unsigned long be_to_le = BITS_PER_LONG - 1;
+	unsigned long bit;
+
+	/* Find non-zero bit starting from 'ivs->next'. */
+	bit = find_next_bit_left(iv->vector, end, start);
+	if (bit >= end)
+		return -1UL;
+	/* Clear interrupt bit (find left uses big-endian bit numbers) */
+	clear_bit(bit ^ be_to_le, iv->vector);
+	return bit;
+}
+EXPORT_SYMBOL(airq_iv_scan);