[PATCH net-next v2 3/8] eth: mpnic: allocate MSI-X vectors

[Daniel Zahka <daniel.zahka@gmail.com>]

Request one vector for FW generated interrupts and then one vector per
CPU to use for the completion queues. Nothing requests a handler yet,
that comes with the NAPI vectors.

Signed-off-by: Daniel Zahka <daniel.zahka@gmail.com>
---
 drivers/net/ethernet/meta/mpnic/Makefile    |  1 +
 drivers/net/ethernet/meta/mpnic/mpnic.h     | 15 +++++++
 drivers/net/ethernet/meta/mpnic/mpnic_irq.c | 64 +++++++++++++++++++++++++++++
 drivers/net/ethernet/meta/mpnic/mpnic_pci.c |  9 +++-
 4 files changed, 88 insertions(+), 1 deletion(-)

diff --git a/drivers/net/ethernet/meta/mpnic/Makefile b/drivers/net/ethernet/meta/mpnic/Makefile
index 9dcaa1c72605..3aa7c6a5ab5e 100644
--- a/drivers/net/ethernet/meta/mpnic/Makefile
+++ b/drivers/net/ethernet/meta/mpnic/Makefile
@@ -9,5 +9,6 @@ obj-$(CONFIG_MPNIC) += mpnic.o
 
 mpnic-y := \
 	mpnic_init.o \
+	mpnic_irq.o \
 	mpnic_pci.o \
 # End of mpnic-y
diff --git a/drivers/net/ethernet/meta/mpnic/mpnic.h b/drivers/net/ethernet/meta/mpnic/mpnic.h
index 67d48b7ce315..628fd48c997d 100644
--- a/drivers/net/ethernet/meta/mpnic/mpnic.h
+++ b/drivers/net/ethernet/meta/mpnic/mpnic.h
@@ -4,6 +4,7 @@
 #ifndef _MPNIC_H_
 #define _MPNIC_H_
 
+#include <linux/interrupt.h>
 #include <linux/io-64-nonatomic-lo-hi.h>
 #include <linux/types.h>
 
@@ -14,11 +15,19 @@
 #define MPNIC_MAX_TXQS		1024u
 #define MPNIC_MAX_RXQS		1024u
 
+/* misc IRQ entries are allocated before the completion queue IRQs */
+enum {
+	MPNIC_FW_MSIX_ENTRY,
+	MPNIC_NON_NAPI_VECTORS
+};
+
 struct mpnic_dev {
 	struct device *dev;
 
 	u32 __iomem *uc_addr0;
 
+	u16 num_irqs;
+
 	u32 mps;
 	u32 readrq;
 	u8 relaxed_ord;
@@ -28,6 +37,12 @@ u64 mpnic_rd64(struct mpnic_dev *mpd, u32 reg);
 
 int mpnic_dev_init(struct mpnic_dev *mpd);
 
+int mpnic_request_irq(struct mpnic_dev *mpd, int nr, irq_handler_t handler,
+		      unsigned long flags, const char *name, void *data);
+void mpnic_free_irq(struct mpnic_dev *mpd, int nr, void *data);
+void mpnic_free_irqs(struct mpnic_dev *mpd);
+int mpnic_alloc_irqs(struct mpnic_dev *mpd);
+
 static inline void mpnic_wr64(struct mpnic_dev *mpd, u32 reg, u64 val)
 {
 	u32 __iomem *csr = READ_ONCE(mpd->uc_addr0);
diff --git a/drivers/net/ethernet/meta/mpnic/mpnic_irq.c b/drivers/net/ethernet/meta/mpnic/mpnic_irq.c
new file mode 100644
index 000000000000..bcc33655cbbe
--- /dev/null
+++ b/drivers/net/ethernet/meta/mpnic/mpnic_irq.c
@@ -0,0 +1,64 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) Meta Platforms, Inc. and affiliates. */
+
+#include <linux/cpumask.h>
+#include <linux/interrupt.h>
+#include <linux/minmax.h>
+#include <linux/pci.h>
+
+#include "mpnic.h"
+
+int mpnic_request_irq(struct mpnic_dev *mpd, int nr, irq_handler_t handler,
+		      unsigned long flags, const char *name, void *data)
+{
+	struct pci_dev *pdev = to_pci_dev(mpd->dev);
+	int irq = pci_irq_vector(pdev, nr);
+
+	if (irq < 0)
+		return irq;
+
+	return request_irq(irq, handler, flags, name, data);
+}
+
+void mpnic_free_irq(struct mpnic_dev *mpd, int nr, void *data)
+{
+	struct pci_dev *pdev = to_pci_dev(mpd->dev);
+	int irq = pci_irq_vector(pdev, nr);
+
+	if (irq < 0)
+		return;
+
+	free_irq(irq, data);
+}
+
+void mpnic_free_irqs(struct mpnic_dev *mpd)
+{
+	struct pci_dev *pdev = to_pci_dev(mpd->dev);
+
+	mpd->num_irqs = 0;
+	pci_free_irq_vectors(pdev);
+}
+
+int mpnic_alloc_irqs(struct mpnic_dev *mpd)
+{
+	unsigned int wanted_irqs = MPNIC_NON_NAPI_VECTORS;
+	struct pci_dev *pdev = to_pci_dev(mpd->dev);
+	int num_irqs;
+
+	wanted_irqs += min_t(unsigned int, num_online_cpus(), MPNIC_MAX_RXQS);
+	num_irqs = pci_alloc_irq_vectors(pdev, MPNIC_NON_NAPI_VECTORS + 1,
+					 wanted_irqs, PCI_IRQ_MSIX);
+	if (num_irqs < 0) {
+		dev_err(mpd->dev, "Failed to allocate MSI-X entries: %d\n",
+			num_irqs);
+		return num_irqs;
+	}
+
+	if (num_irqs < wanted_irqs)
+		dev_warn(mpd->dev, "Allocated %d IRQs, expected %u\n",
+			 num_irqs, wanted_irqs);
+
+	mpd->num_irqs = num_irqs;
+
+	return 0;
+}
diff --git a/drivers/net/ethernet/meta/mpnic/mpnic_pci.c b/drivers/net/ethernet/meta/mpnic/mpnic_pci.c
index 68a64377e6c5..127b71b44b0f 100644
--- a/drivers/net/ethernet/meta/mpnic/mpnic_pci.c
+++ b/drivers/net/ethernet/meta/mpnic/mpnic_pci.c
@@ -112,12 +112,18 @@ static int mpnic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	pci_set_master(pdev);
 	pci_save_state(pdev);
 
-	err = mpnic_dev_init(mpd);
+	err = mpnic_alloc_irqs(mpd);
 	if (err)
 		goto err_free_mpd;
 
+	err = mpnic_dev_init(mpd);
+	if (err)
+		goto err_free_irqs;
+
 	return 0;
 
+err_free_irqs:
+	mpnic_free_irqs(mpd);
 err_free_mpd:
 	kfree(mpd);
 
@@ -132,6 +138,7 @@ static void mpnic_remove(struct pci_dev *pdev)
 {
 	struct mpnic_dev *mpd = pci_get_drvdata(pdev);
 
+	mpnic_free_irqs(mpd);
 	kfree(mpd);
 }
 

-- 
2.52.0