linux-kernel - [PATCH 2/2] cxl/mbox: Wire up irq support

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Date:   Mon, 17 Oct 2022 20:00:10 -0700
From:   Davidlohr Bueso <dave@...olabs.net>
To:     dan.j.williams@...el.com
Cc:     ira.weiny@...el.com, Jonathan.Cameron@...wei.com,
        dave.jiang@...el.com, alison.schofield@...el.com,
        bwidawsk@...nel.org, vishal.l.verma@...el.com,
        a.manzanares@...sung.com, linux-cxl@...r.kernel.org,
        linux-kernel@...r.kernel.org, dave@...olabs.net
Subject: [PATCH 2/2] cxl/mbox: Wire up irq support

With enough vectors properly allocated, this adds support for
(the primary) mailbox interrupt, which is needed for background
completion handling, beyond polling.

Signed-off-by: Davidlohr Bueso <dave@...olabs.net>
---
 drivers/cxl/cxl.h |  1 +
 drivers/cxl/pci.c | 29 ++++++++++++++++++++++++++++-
 2 files changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/cxl/cxl.h b/drivers/cxl/cxl.h
index f680450f0b16..13a9743b0012 100644
--- a/drivers/cxl/cxl.h
+++ b/drivers/cxl/cxl.h
@@ -135,6 +135,7 @@ static inline int ways_to_cxl(unsigned int ways, u8 *iw)
 /* CXL 2.0 8.2.8.4 Mailbox Registers */
 #define CXLDEV_MBOX_CAPS_OFFSET 0x00
 #define   CXLDEV_MBOX_CAP_PAYLOAD_SIZE_MASK GENMASK(4, 0)
+#define   CXLDEV_MBOX_CAP_IRQ_MSGNUM_MASK GENMASK(10, 7)
 #define CXLDEV_MBOX_CTRL_OFFSET 0x04
 #define   CXLDEV_MBOX_CTRL_DOORBELL BIT(0)
 #define CXLDEV_MBOX_CMD_OFFSET 0x08
diff --git a/drivers/cxl/pci.c b/drivers/cxl/pci.c
index 9c3e95ebaa26..c3f3ee307d7a 100644
--- a/drivers/cxl/pci.c
+++ b/drivers/cxl/pci.c
@@ -274,6 +274,32 @@ static int cxl_pci_setup_mailbox(struct cxl_dev_state *cxlds)
 	return 0;
 }
 
+static int cxl_pci_mbox_get_max_msgnum(struct cxl_dev_state *cxlds)
+{
+	int cap;
+
+	cap = readl(cxlds->regs.mbox + CXLDEV_MBOX_CAPS_OFFSET);
+	return FIELD_GET(CXLDEV_MBOX_CAP_IRQ_MSGNUM_MASK, cap);
+}
+
+static irqreturn_t cxl_pci_mbox_irq(int irq, void *id)
+{
+	/* TODO: handle completion of background commands */
+	return IRQ_HANDLED;
+}
+
+static void cxl_pci_mbox_irqsetup(struct cxl_dev_state *cxlds)
+{
+	struct device *dev = cxlds->dev;
+	struct pci_dev *pdev = to_pci_dev(dev);
+	int irq;
+
+	irq = cxl_pci_mbox_get_max_msgnum(cxlds);
+	if (!pci_request_irq(pdev, irq, cxl_pci_mbox_irq, NULL,
+			     cxlds, "%s-mailbox", dev_name(dev)))
+		dev_dbg(dev, "Mailbox irq (%d) supported", irq);
+}
+
 static int cxl_map_regblock(struct pci_dev *pdev, struct cxl_register_map *map)
 {
 	void __iomem *addr;
@@ -442,7 +468,7 @@ struct cxl_irq_cap {
 };
 
 static const struct cxl_irq_cap cxl_irq_cap_table[] = {
-	NULL
+	{ "mailbox", cxl_pci_mbox_get_max_msgnum },
 };
 
 static void cxl_pci_free_irq_vectors(void *data)
@@ -562,6 +588,7 @@ static int cxl_pci_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 		return rc;
 
 	if (!cxl_pci_alloc_irq_vectors(cxlds)) {
+		cxl_pci_mbox_irqsetup(cxlds);
 		cxlds->has_irq = true;
 	} else
 		cxlds->has_irq = false;
-- 
2.38.0