ocxl: Add AFU interrupt support

Add user APIs through ioctl to allocate, free, and be notified of an
AFU interrupt.

For opencapi, an AFU can trigger an interrupt on the host by sending a
specific command targeting a 64-bit object handle. On POWER9, this is
implemented by mapping a special page in the address space of a
process and a write to that page will trigger an interrupt.

Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

1 files changed, 28 insertions, 0 deletions

diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c
index 64d7a98c904a..8bdcef9c3cba 100644
--- a/drivers/misc/ocxl/link.c
+++ b/drivers/misc/ocxl/link.c
@@ -601,3 +601,31 @@ unlock:
 	mutex_unlock(&spa->spa_lock);
 	return rc;
 }
+
+int ocxl_link_irq_alloc(void *link_handle, int *hw_irq, u64 *trigger_addr)
+{
+	struct link *link = (struct link *) link_handle;
+	int rc, irq;
+	u64 addr;
+
+	if (atomic_dec_if_positive(&link->irq_available) < 0)
+		return -ENOSPC;
+
+	rc = pnv_ocxl_alloc_xive_irq(&irq, &addr);
+	if (rc) {
+		atomic_inc(&link->irq_available);
+		return rc;
+	}
+
+	*hw_irq = irq;
+	*trigger_addr = addr;
+	return 0;
+}
+
+void ocxl_link_free_irq(void *link_handle, int hw_irq)
+{
+	struct link *link = (struct link *) link_handle;
+
+	pnv_ocxl_free_xive_irq(hw_irq);
+	atomic_inc(&link->irq_available);
+}