[PATCH 3/4] RDMA/ionic: map PHC state into user space

[Abhijit Gangurde <abhijit.gangurde@amd.com>]

Enable user space applications to access the PHC state page when
firmware RDMA completion timestamp is supported.

This mapping allows user space to convert RDMA completion timestamps
to system wall time without kernel transitions, minimizing latency
overhead. Applications can directly read the PHC state through mmap,
enabling efficient timestamp correlation for precision timing
applications.

Co-developed-by: Allen Hubbe <allen.hubbe@amd.com>
Signed-off-by: Allen Hubbe <allen.hubbe@amd.com>
Signed-off-by: Abhijit Gangurde <abhijit.gangurde@amd.com>
---
 .../infiniband/hw/ionic/ionic_controlpath.c   | 36 ++++++++++++++++++-
 drivers/infiniband/hw/ionic/ionic_ibdev.h     |  2 ++
 drivers/infiniband/hw/ionic/ionic_lif_cfg.c   |  2 ++
 drivers/infiniband/hw/ionic/ionic_lif_cfg.h   |  1 +
 include/uapi/rdma/ionic-abi.h                 |  1 +
 5 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/drivers/infiniband/hw/ionic/ionic_controlpath.c b/drivers/infiniband/hw/ionic/ionic_controlpath.c
index a5671da3db64..5a0b189f9855 100644
--- a/drivers/infiniband/hw/ionic/ionic_controlpath.c
+++ b/drivers/infiniband/hw/ionic/ionic_controlpath.c
@@ -391,6 +391,16 @@ int ionic_alloc_ucontext(struct ib_ucontext *ibctx, struct ib_udata *udata)
 		goto err_mmap_dbell;
 	}
 
+	if (dev->lif_cfg.phc_state) {
+		ctx->mmap_phc = ionic_mmap_entry_insert(ctx, PAGE_SIZE, 0,
+							IONIC_MMAP_PHC,
+							&resp.phc_offset);
+		if (!ctx->mmap_phc) {
+			rc = -ENOMEM;
+			goto err_mmap_phc;
+		}
+	}
+
 	resp.page_shift = PAGE_SHIFT;
 
 	resp.dbell_offset = db_phys & ~PAGE_MASK;
@@ -414,13 +424,15 @@ int ionic_alloc_ucontext(struct ib_ucontext *ibctx, struct ib_udata *udata)
 	if (dev->lif_cfg.rq_expdb)
 		resp.expdb_qtypes |= IONIC_EXPDB_RQ;
 
-	rc = ib_copy_to_udata(udata, &resp, sizeof(resp));
+	rc = ib_respond_udata(udata, resp);
 	if (rc)
 		goto err_resp;
 
 	return 0;
 
 err_resp:
+	rdma_user_mmap_entry_remove(ctx->mmap_phc);
+err_mmap_phc:
 	rdma_user_mmap_entry_remove(ctx->mmap_dbell);
 err_mmap_dbell:
 	ionic_put_dbid(dev, ctx->dbid);
@@ -433,10 +445,26 @@ void ionic_dealloc_ucontext(struct ib_ucontext *ibctx)
 	struct ionic_ibdev *dev = to_ionic_ibdev(ibctx->device);
 	struct ionic_ctx *ctx = to_ionic_ctx(ibctx);
 
+	rdma_user_mmap_entry_remove(ctx->mmap_phc);
 	rdma_user_mmap_entry_remove(ctx->mmap_dbell);
 	ionic_put_dbid(dev, ctx->dbid);
 }
 
+static int ionic_mmap_phc_stage(struct ionic_ibdev *dev,
+				struct vm_area_struct *vma)
+{
+	if (!(vma->vm_flags & VM_SHARED))
+		return -EINVAL;
+
+	if (vma->vm_flags & (VM_WRITE | VM_EXEC))
+		return -EPERM;
+
+	vm_flags_clear(vma, VM_MAYWRITE);
+
+	return vm_insert_page(vma, vma->vm_start,
+			      virt_to_page(dev->lif_cfg.phc_state));
+}
+
 int ionic_mmap(struct ib_ucontext *ibctx, struct vm_area_struct *vma)
 {
 	struct ionic_ibdev *dev = to_ionic_ibdev(ibctx->device);
@@ -455,6 +483,12 @@ int ionic_mmap(struct ib_ucontext *ibctx, struct vm_area_struct *vma)
 	ionic_entry = container_of(rdma_entry, struct ionic_mmap_entry,
 				   rdma_entry);
 
+	if (ionic_entry->mmap_flags & IONIC_MMAP_PHC) {
+		rc = ionic_mmap_phc_stage(dev, vma);
+		rdma_user_mmap_entry_put(rdma_entry);
+		return rc;
+	}
+
 	ibdev_dbg(&dev->ibdev, "writecombine? %d\n",
 		  ionic_entry->mmap_flags & IONIC_MMAP_WC);
 	if (ionic_entry->mmap_flags & IONIC_MMAP_WC)
diff --git a/drivers/infiniband/hw/ionic/ionic_ibdev.h b/drivers/infiniband/hw/ionic/ionic_ibdev.h
index 63828240d659..08655c4d8297 100644
--- a/drivers/infiniband/hw/ionic/ionic_ibdev.h
+++ b/drivers/infiniband/hw/ionic/ionic_ibdev.h
@@ -72,6 +72,7 @@ enum ionic_admin_flags {
 
 enum ionic_mmap_flag {
 	IONIC_MMAP_WC = BIT(0),
+	IONIC_MMAP_PHC = BIT(1),
 };
 
 struct ionic_mmap_entry {
@@ -173,6 +174,7 @@ struct ionic_ctx {
 	struct ib_ucontext	ibctx;
 	u32			dbid;
 	struct rdma_user_mmap_entry	*mmap_dbell;
+	struct rdma_user_mmap_entry	*mmap_phc;
 };
 
 struct ionic_tbl_buf {
diff --git a/drivers/infiniband/hw/ionic/ionic_lif_cfg.c b/drivers/infiniband/hw/ionic/ionic_lif_cfg.c
index f3cd281c3a2f..e3f2df1f9e6a 100644
--- a/drivers/infiniband/hw/ionic/ionic_lif_cfg.c
+++ b/drivers/infiniband/hw/ionic/ionic_lif_cfg.c
@@ -40,6 +40,8 @@ void ionic_fill_lif_cfg(struct ionic_lif *lif, struct ionic_lif_cfg *cfg)
 	cfg->dbid_count = le32_to_cpu(lif->ionic->ident.dev.ndbpgs_per_lif);
 	cfg->dbpage = lif->kern_dbpage;
 	cfg->intr_ctrl = lif->ionic->idev.intr_ctrl;
+	if (ident->eth.config.features & cpu_to_le64(IONIC_ETH_HW_RDMA_TIMESTAMP))
+		cfg->phc_state = lif->phc->state_page;
 
 	cfg->db_phys = lif->ionic->bars[IONIC_PCI_BAR_DBELL].bus_addr;
 
diff --git a/drivers/infiniband/hw/ionic/ionic_lif_cfg.h b/drivers/infiniband/hw/ionic/ionic_lif_cfg.h
index 20853429f623..2b29e646c193 100644
--- a/drivers/infiniband/hw/ionic/ionic_lif_cfg.h
+++ b/drivers/infiniband/hw/ionic/ionic_lif_cfg.h
@@ -23,6 +23,7 @@ struct ionic_lif_cfg {
 	u64 __iomem *dbpage;
 	struct ionic_intr __iomem *intr_ctrl;
 	phys_addr_t db_phys;
+	void *phc_state;
 
 	u64 page_size_supported;
 	u32 npts_per_lif;
diff --git a/include/uapi/rdma/ionic-abi.h b/include/uapi/rdma/ionic-abi.h
index 97f695510380..abd1bde0991f 100644
--- a/include/uapi/rdma/ionic-abi.h
+++ b/include/uapi/rdma/ionic-abi.h
@@ -48,6 +48,7 @@ struct ionic_ctx_resp {
 	__u8 expdb_qtypes;
 
 	__u8 rsvd2[3];
+	__aligned_u64 phc_offset;
 };
 
 struct ionic_qdesc {
-- 
2.43.0