1 files changed, 154 insertions, 0 deletions
diff --git a/drivers/infiniband/hw/ionic/ionic_res.h b/drivers/infiniband/hw/ionic/ionic_res.h
new file mode 100644
index 000000000000..46c8c584bd9a
--- /dev/null
+++ b/drivers/infiniband/hw/ionic/ionic_res.h
@@ -0,0 +1,154 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (C) 2018-2025, Advanced Micro Devices, Inc. */
+
+#ifndef _IONIC_RES_H_
+#define _IONIC_RES_H_
+
+#include <linux/kernel.h>
+#include <linux/idr.h>
+
+/**
+ * struct ionic_resid_bits - Number allocator based on IDA
+ *
+ * @inuse:      IDA handle
+ * @inuse_size: Highest ID limit for IDA
+ */
+struct ionic_resid_bits {
+	struct ida inuse;
+	unsigned int inuse_size;
+};
+
+/**
+ * ionic_resid_init() - Initialize a resid allocator
+ * @resid:  Uninitialized resid allocator
+ * @size:   Capacity of the allocator
+ *
+ * Return: Zero on success, or negative error number
+ */
+static inline void ionic_resid_init(struct ionic_resid_bits *resid,
+				    unsigned int size)
+{
+	resid->inuse_size = size;
+	ida_init(&resid->inuse);
+}
+
+/**
+ * ionic_resid_destroy() - Destroy a resid allocator
+ * @resid:  Resid allocator
+ */
+static inline void ionic_resid_destroy(struct ionic_resid_bits *resid)
+{
+	ida_destroy(&resid->inuse);
+}
+
+/**
+ * ionic_resid_get_shared() - Allocate an available shared resource id
+ * @resid:   Resid allocator
+ * @min:     Smallest valid resource id
+ * @size:    One after largest valid resource id
+ *
+ * Return: Resource id, or negative error number
+ */
+static inline int ionic_resid_get_shared(struct ionic_resid_bits *resid,
+					 unsigned int min,
+					 unsigned int size)
+{
+	return ida_alloc_range(&resid->inuse, min, size - 1, GFP_KERNEL);
+}
+
+/**
+ * ionic_resid_get() - Allocate an available resource id
+ * @resid: Resid allocator
+ *
+ * Return: Resource id, or negative error number
+ */
+static inline int ionic_resid_get(struct ionic_resid_bits *resid)
+{
+	return ionic_resid_get_shared(resid, 0, resid->inuse_size);
+}
+
+/**
+ * ionic_resid_put() - Free a resource id
+ * @resid:  Resid allocator
+ * @id:     Resource id
+ */
+static inline void ionic_resid_put(struct ionic_resid_bits *resid, int id)
+{
+	ida_free(&resid->inuse, id);
+}
+
+/**
+ * ionic_bitid_to_qid() - Transform a resource bit index into a queue id
+ * @bitid:           Bit index
+ * @qgrp_shift:      Log2 number of queues per queue group
+ * @half_qid_shift:  Log2 of half the total number of queues
+ *
+ * Return: Queue id
+ *
+ * Udma-constrained queues (QPs and CQs) are associated with their udma by
+ * queue group. Even queue groups are associated with udma0, and odd queue
+ * groups with udma1.
+ *
+ * For allocating queue ids, we want to arrange the bits into two halves,
+ * with the even queue groups of udma0 in the lower half of the bitset,
+ * and the odd queue groups of udma1 in the upper half of the bitset.
+ * Then, one or two calls of find_next_zero_bit can examine all the bits
+ * for queues of an entire udma.
+ *
+ * For example, assuming eight queue groups with qgrp qids per group:
+ *
+ * bitid 0*qgrp..1*qgrp-1 : qid 0*qgrp..1*qgrp-1
+ * bitid 1*qgrp..2*qgrp-1 : qid 2*qgrp..3*qgrp-1
+ * bitid 2*qgrp..3*qgrp-1 : qid 4*qgrp..5*qgrp-1
+ * bitid 3*qgrp..4*qgrp-1 : qid 6*qgrp..7*qgrp-1
+ * bitid 4*qgrp..5*qgrp-1 : qid 1*qgrp..2*qgrp-1
+ * bitid 5*qgrp..6*qgrp-1 : qid 3*qgrp..4*qgrp-1
+ * bitid 6*qgrp..7*qgrp-1 : qid 5*qgrp..6*qgrp-1
+ * bitid 7*qgrp..8*qgrp-1 : qid 7*qgrp..8*qgrp-1
+ *
+ * There are three important ranges of bits in the qid.  There is the udma
+ * bit "U" at qgrp_shift, which is the least significant bit of the group
+ * index, and determines which udma a queue is associated with.
+ * The bits of lesser significance we can call the idx bits "I", which are
+ * the index of the queue within the group.  The bits of greater significance
+ * we can call the grp bits "G", which are other bits of the group index that
+ * do not determine the udma.  Those bits are just rearranged in the bit index
+ * in the bitset.  A bitid has the udma bit in the most significant place,
+ * then the grp bits, then the idx bits.
+ *
+ * bitid: 00000000000000 U GGG IIIIII
+ * qid:   00000000000000 GGG U IIIIII
+ *
+ * Transforming from bit index to qid, or from qid to bit index, can be
+ * accomplished by rearranging the bits by masking and shifting.
+ */
+static inline u32 ionic_bitid_to_qid(u32 bitid, u8 qgrp_shift,
+				     u8 half_qid_shift)
+{
+	u32 udma_bit =
+		(bitid & BIT(half_qid_shift)) >> (half_qid_shift - qgrp_shift);
+	u32 grp_bits = (bitid & GENMASK(half_qid_shift - 1, qgrp_shift)) << 1;
+	u32 idx_bits = bitid & (BIT(qgrp_shift) - 1);
+
+	return grp_bits | udma_bit | idx_bits;
+}
+
+/**
+ * ionic_qid_to_bitid() - Transform a queue id into a resource bit index
+ * @qid:            queue index
+ * @qgrp_shift:     Log2 number of queues per queue group
+ * @half_qid_shift: Log2 of half the total number of queues
+ *
+ * Return: Resource bit index
+ *
+ * This is the inverse of ionic_bitid_to_qid().
+ */
+static inline u32 ionic_qid_to_bitid(u32 qid, u8 qgrp_shift, u8 half_qid_shift)
+{
+	u32 udma_bit = (qid & BIT(qgrp_shift)) << (half_qid_shift - qgrp_shift);
+	u32 grp_bits = (qid & GENMASK(half_qid_shift, qgrp_shift + 1)) >> 1;
+	u32 idx_bits = qid & (BIT(qgrp_shift) - 1);
+
+	return udma_bit | grp_bits | idx_bits;
+}
+#endif /* _IONIC_RES_H_ */