linux-kernel - [PATCH v3 13/16] switchtec_ntb: implement doorbell registers

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Date:   Tue, 25 Jul 2017 14:57:50 -0600
From:   Logan Gunthorpe <logang@...tatee.com>
To:     linux-ntb@...glegroups.com, linux-pci@...r.kernel.org,
        linux-kernel@...r.kernel.org
Cc:     Jon Mason <jdmason@...zu.us>, Dave Jiang <dave.jiang@...el.com>,
        Allen Hubbe <Allen.Hubbe@....com>,
        Bjorn Helgaas <bhelgaas@...gle.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Kurt Schwemmer <kurt.schwemmer@...rosemi.com>,
        Stephen Bates <sbates@...thlin.com>,
        Serge Semin <fancer.lancer@...il.com>,
        Logan Gunthorpe <logang@...tatee.com>
Subject: [PATCH v3 13/16] switchtec_ntb: implement doorbell registers

Pretty straightforward implementation of doorbell registers.
The shift and mask were setup in an earlier patch and this just hooks
up the appropriate portion of the IDB register as the local doorbells
and the opposite portion of ODB as the peer doorbells. The DB mask is
protected by a spinlock to avoid concurrent read-modify-write accesses.

Signed-off-by: Logan Gunthorpe <logang@...tatee.com>
Reviewed-by: Stephen Bates <sbates@...thlin.com>
Reviewed-by: Kurt Schwemmer <kurt.schwemmer@...rosemi.com>
---
 drivers/ntb/hw/mscc/switchtec_ntb.c | 89 +++++++++++++++++++++++++++++++++++--
 1 file changed, 85 insertions(+), 4 deletions(-)

diff --git a/drivers/ntb/hw/mscc/switchtec_ntb.c b/drivers/ntb/hw/mscc/switchtec_ntb.c
index 34d69fa8612d..3037ca730998 100644
--- a/drivers/ntb/hw/mscc/switchtec_ntb.c
+++ b/drivers/ntb/hw/mscc/switchtec_ntb.c
@@ -98,6 +98,9 @@ struct switchtec_ntb {
 	int db_shift;
 	int db_peer_shift;
 
+	/* synchronize rmw access of db_mask and hw reg */
+	spinlock_t db_mask_lock;
+
 	int nr_direct_mw;
 	int nr_lut_mw;
 	int direct_mw_to_bar[MAX_DIRECT_MW];
@@ -338,41 +341,115 @@ static int switchtec_ntb_link_disable(struct ntb_dev *ntb)
 
 static u64 switchtec_ntb_db_valid_mask(struct ntb_dev *ntb)
 {
-	return 0;
+	struct switchtec_ntb *sndev = ntb_sndev(ntb);
+
+	return sndev->db_valid_mask;
 }
 
 static int switchtec_ntb_db_vector_count(struct ntb_dev *ntb)
 {
-	return 0;
+	return 1;
 }
 
 static u64 switchtec_ntb_db_vector_mask(struct ntb_dev *ntb, int db_vector)
 {
-	return 0;
+	struct switchtec_ntb *sndev = ntb_sndev(ntb);
+
+	if (db_vector < 0 || db_vector > 1)
+		return 0;
+
+	return sndev->db_valid_mask;
 }
 
 static u64 switchtec_ntb_db_read(struct ntb_dev *ntb)
 {
-	return 0;
+	u64 ret;
+	struct switchtec_ntb *sndev = ntb_sndev(ntb);
+
+	ret = ioread64(&sndev->mmio_self_dbmsg->idb) >> sndev->db_shift;
+
+	return ret & sndev->db_valid_mask;
 }
 
 static int switchtec_ntb_db_clear(struct ntb_dev *ntb, u64 db_bits)
 {
+	struct switchtec_ntb *sndev = ntb_sndev(ntb);
+
+	iowrite64(db_bits << sndev->db_shift, &sndev->mmio_self_dbmsg->idb);
+
 	return 0;
 }
 
 static int switchtec_ntb_db_set_mask(struct ntb_dev *ntb, u64 db_bits)
 {
+	unsigned long irqflags;
+	struct switchtec_ntb *sndev = ntb_sndev(ntb);
+
+	if (db_bits & ~sndev->db_valid_mask)
+		return -EINVAL;
+
+	spin_lock_irqsave(&sndev->db_mask_lock, irqflags);
+	{
+		sndev->db_mask |= db_bits << sndev->db_shift;
+		iowrite64(~sndev->db_mask, &sndev->mmio_self_dbmsg->idb_mask);
+	}
+	spin_unlock_irqrestore(&sndev->db_mask_lock, irqflags);
+
 	return 0;
 }
 
 static int switchtec_ntb_db_clear_mask(struct ntb_dev *ntb, u64 db_bits)
 {
+	unsigned long irqflags;
+	struct switchtec_ntb *sndev = ntb_sndev(ntb);
+
+	if (db_bits & ~sndev->db_valid_mask)
+		return -EINVAL;
+
+	spin_lock_irqsave(&sndev->db_mask_lock, irqflags);
+	{
+		sndev->db_mask &= ~(db_bits << sndev->db_shift);
+		iowrite64(~sndev->db_mask, &sndev->mmio_self_dbmsg->idb_mask);
+	}
+	spin_unlock_irqrestore(&sndev->db_mask_lock, irqflags);
+
+	return 0;
+}
+
+static u64 switchtec_ntb_db_read_mask(struct ntb_dev *ntb)
+{
+	struct switchtec_ntb *sndev = ntb_sndev(ntb);
+
+	return (sndev->db_mask >> sndev->db_shift) & sndev->db_valid_mask;
+}
+
+static int switchtec_ntb_peer_db_addr(struct ntb_dev *ntb,
+				      phys_addr_t *db_addr,
+				      resource_size_t *db_size)
+{
+	struct switchtec_ntb *sndev = ntb_sndev(ntb);
+	unsigned long offset;
+
+	offset = (unsigned long)sndev->mmio_self_dbmsg->odb -
+		(unsigned long)sndev->stdev->mmio;
+
+	offset += sndev->db_shift / 8;
+
+	if (db_addr)
+		*db_addr = pci_resource_start(ntb->pdev, 0) + offset;
+	if (db_size)
+		*db_size = sizeof(u32);
+
 	return 0;
 }
 
 static int switchtec_ntb_peer_db_set(struct ntb_dev *ntb, u64 db_bits)
 {
+	struct switchtec_ntb *sndev = ntb_sndev(ntb);
+
+	iowrite64(db_bits << sndev->db_peer_shift,
+		  &sndev->mmio_self_dbmsg->odb);
+
 	return 0;
 }
 
@@ -413,6 +490,8 @@ static const struct ntb_dev_ops switchtec_ntb_ops = {
 	.db_clear		= switchtec_ntb_db_clear,
 	.db_set_mask		= switchtec_ntb_db_set_mask,
 	.db_clear_mask		= switchtec_ntb_db_clear_mask,
+	.db_read_mask		= switchtec_ntb_db_read_mask,
+	.peer_db_addr		= switchtec_ntb_peer_db_addr,
 	.peer_db_set		= switchtec_ntb_peer_db_set,
 	.spad_count		= switchtec_ntb_spad_count,
 	.spad_read		= switchtec_ntb_spad_read,
@@ -680,6 +759,8 @@ static irqreturn_t switchtec_ntb_doorbell_isr(int irq, void *dev)
 
 	dev_dbg(&sndev->stdev->dev, "doorbell\n");
 
+	ntb_db_event(&sndev->ntb, 0);
+
 	return IRQ_HANDLED;
 }
 
-- 
2.11.0