[PATCH iwl-next,v1 2/3] igc: Add default Rx queue configuration via sysfs

[Song Yoong Siang]

From: Blanco Alcaine Hector <hector.blanco.alcaine@xxxxxxxxx>

This commit introduces the support to configure default Rx queue during
runtime. A new sysfs attribute "default_rx_queue" has been added, allowing
users to check and modify the default Rx queue.

1. Command to check the currently configured default Rx queue:
   cat /sys/devices/pci0000:00/.../default_rx_queue

2. Command to set the default Rx queue to a desired value, for example 3:
   echo 3 > /sys/devices/pci0000:00/.../default_rx_queue

Signed-off-by: Blanco Alcaine Hector <hector.blanco.alcaine@xxxxxxxxx>
Signed-off-by: Song Yoong Siang <yoong.siang.song@xxxxxxxxx>
---
 drivers/net/ethernet/intel/igc/Makefile    |   3 +-
 drivers/net/ethernet/intel/igc/igc_main.c  |   6 +
 drivers/net/ethernet/intel/igc/igc_regs.h  |   6 +
 drivers/net/ethernet/intel/igc/igc_sysfs.c | 156 +++++++++++++++++++++
 drivers/net/ethernet/intel/igc/igc_sysfs.h |  10 ++
 5 files changed, 180 insertions(+), 1 deletion(-)
 create mode 100644 drivers/net/ethernet/intel/igc/igc_sysfs.c
 create mode 100644 drivers/net/ethernet/intel/igc/igc_sysfs.h

diff --git a/drivers/net/ethernet/intel/igc/Makefile b/drivers/net/ethernet/intel/igc/Makefile
index efc5e7983dad..c31bc18ede13 100644
--- a/drivers/net/ethernet/intel/igc/Makefile
+++ b/drivers/net/ethernet/intel/igc/Makefile
@@ -8,5 +8,6 @@
 obj-$(CONFIG_IGC) += igc.o
 
 igc-y := igc_main.o igc_mac.o igc_i225.o igc_base.o igc_nvm.o igc_phy.o \
-	 igc_diag.o igc_ethtool.o igc_ptp.o igc_dump.o igc_tsn.o igc_xdp.o
+	 igc_diag.o igc_ethtool.o igc_ptp.o igc_dump.o igc_tsn.o igc_xdp.o \
+	 igc_sysfs.o
 igc-$(CONFIG_IGC_LEDS) += igc_leds.o
diff --git a/drivers/net/ethernet/intel/igc/igc_main.c b/drivers/net/ethernet/intel/igc/igc_main.c
index cb5c7b09e8a0..6a925615911a 100644
--- a/drivers/net/ethernet/intel/igc/igc_main.c
+++ b/drivers/net/ethernet/intel/igc/igc_main.c
@@ -18,6 +18,7 @@
 
 #include "igc.h"
 #include "igc_hw.h"
+#include "igc_sysfs.h"
 #include "igc_tsn.h"
 #include "igc_xdp.h"
 
@@ -7069,6 +7070,9 @@ static int igc_probe(struct pci_dev *pdev,
 			goto err_register;
 	}
 
+	if (igc_sysfs_init(adapter))
+		dev_err(&pdev->dev, "Failed to allocate sysfs resources\n");
+
 	return 0;
 
 err_register:
@@ -7124,6 +7128,8 @@ static void igc_remove(struct pci_dev *pdev)
 	if (IS_ENABLED(CONFIG_IGC_LEDS))
 		igc_led_free(adapter);
 
+	igc_sysfs_exit(adapter);
+
 	/* Release control of h/w to f/w.  If f/w is AMT enabled, this
 	 * would have already happened in close and is redundant.
 	 */
diff --git a/drivers/net/ethernet/intel/igc/igc_regs.h b/drivers/net/ethernet/intel/igc/igc_regs.h
index e5b893fc5b66..df96800f6e3b 100644
--- a/drivers/net/ethernet/intel/igc/igc_regs.h
+++ b/drivers/net/ethernet/intel/igc/igc_regs.h
@@ -63,6 +63,12 @@
 /* RSS registers */
 #define IGC_MRQC		0x05818 /* Multiple Receive Control - RW */
 
+/* MRQC register bit definitions */
+#define IGC_MRQC_ENABLE_MQ		0x00000000
+#define IGC_MRQC_ENABLE_MASK		GENMASK(2, 0)
+#define IGC_MRQC_DEFAULT_QUEUE_MASK	GENMASK(5, 3)
+#define IGC_MRQC_DEFAULT_QUEUE_SHIFT	3
+
 /* Filtering Registers */
 #define IGC_ETQF(_n)		(0x05CB0 + (4 * (_n))) /* EType Queue Fltr */
 #define IGC_FHFT(_n)		(0x09000 + (256 * (_n))) /* Flexible Host Filter */
diff --git a/drivers/net/ethernet/intel/igc/igc_sysfs.c b/drivers/net/ethernet/intel/igc/igc_sysfs.c
new file mode 100644
index 000000000000..34d838e6a019
--- /dev/null
+++ b/drivers/net/ethernet/intel/igc/igc_sysfs.c
@@ -0,0 +1,156 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2024 Intel Corporation */
+
+#include <linux/device.h>
+#include <linux/kobject.h>
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/sysfs.h>
+#include <linux/types.h>
+
+#include "igc.h"
+#include "igc_regs.h"
+#include "igc_sysfs.h"
+
+/**
+ * igc_is_default_queue_supported - Checks if default Rx queue can be configured
+ * @mrqc: MRQC register content
+ *
+ * Checks if the current configuration of the device supports changing the
+ * default Rx queue configuration.
+ *
+ * Return: true if the default Rx queue can be configured, false otherwise.
+ */
+static bool igc_is_default_queue_supported(u32 mrqc)
+{
+	u32 mrqe = mrqc & IGC_MRQC_ENABLE_MASK;
+
+	/* The default Rx queue setting is applied only if Multiple Receive
+	 * Queues (MRQ) as defined by filters (2-tuple filters, L2 Ether-type
+	 * filters, SYN filter and flex filters) is enabled.
+	 */
+	if (mrqe != IGC_MRQC_ENABLE_MQ && mrqe != IGC_MRQC_ENABLE_RSS_MQ)
+		return false;
+
+	return true;
+}
+
+/**
+ * igc_get_default_rx_queue - Returns the index of default Rx queue
+ * @adapter: address of board private structure
+ *
+ * Return: index of the default Rx queue.
+ */
+static u32 igc_get_default_rx_queue(struct igc_adapter *adapter)
+{
+	struct igc_hw *hw = &adapter->hw;
+	u32 mrqc = rd32(IGC_MRQC);
+
+	if (!igc_is_default_queue_supported(mrqc)) {
+		netdev_warn(adapter->netdev,
+			    "MRQ disabled: default RxQ is ignored.\n");
+	}
+
+	return (mrqc & IGC_MRQC_DEFAULT_QUEUE_MASK) >>
+		IGC_MRQC_DEFAULT_QUEUE_SHIFT;
+}
+
+/**
+ * igc_set_default_rx_queue - Sets the default Rx queue
+ * @adapter: address of board private structure
+ * @queue: index of the queue to be set as default Rx queue
+ *
+ * Return: 0 on success, negative error code on failure.
+ */
+static int igc_set_default_rx_queue(struct igc_adapter *adapter, u32 queue)
+{
+	struct igc_hw *hw = &adapter->hw;
+	u32 mrqc = rd32(IGC_MRQC);
+
+	if (!igc_is_default_queue_supported(mrqc)) {
+		netdev_err(adapter->netdev,
+			   "Default RxQ not supported. Please enable MRQ.\n");
+		return -EOPNOTSUPP;
+	}
+
+	if (queue > adapter->rss_queues - 1) {
+		netdev_err(adapter->netdev,
+			   "Invalid default RxQ index %d. Valid range: 0-%u.\n",
+			   queue, adapter->rss_queues - 1);
+		return -EINVAL;
+	}
+
+	/* Set the default Rx queue */
+	mrqc = rd32(IGC_MRQC);
+	mrqc &= ~IGC_MRQC_DEFAULT_QUEUE_MASK;
+	mrqc |= queue << IGC_MRQC_DEFAULT_QUEUE_SHIFT;
+	wr32(IGC_MRQC, mrqc);
+
+	return 0;
+}
+
+static ssize_t default_rx_queue_show(struct device *dev,
+				     struct device_attribute *attr,
+				     char *buf)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct net_device *netdev = pci_get_drvdata(pdev);
+	struct igc_adapter *adapter = netdev_priv(netdev);
+	u32 default_rx_queue = igc_get_default_rx_queue(adapter);
+
+	return sysfs_emit(buf, "%d\n", default_rx_queue);
+}
+
+static ssize_t default_rx_queue_store(struct device *dev,
+				      struct device_attribute *attr,
+				      const char *buf, size_t count)
+{
+	struct pci_dev *pdev = to_pci_dev(dev);
+	struct net_device *netdev = pci_get_drvdata(pdev);
+	struct igc_adapter *adapter = netdev_priv(netdev);
+	u32 default_rx_queue;
+	int err;
+
+	err = kstrtou32(buf, 10, &default_rx_queue);
+	if (err) {
+		netdev_err(adapter->netdev,
+			   "Invalid default RxQ index. Valid range: 0-%u.\n",
+			   adapter->rss_queues - 1);
+		return err;
+	}
+
+	err = igc_set_default_rx_queue(adapter, default_rx_queue);
+	if (err < 0)
+		return -EINVAL;
+
+	return count;
+}
+
+static DEVICE_ATTR_RW(default_rx_queue);
+
+static struct attribute *attrs[] = {
+	&dev_attr_default_rx_queue.attr,
+	NULL,
+};
+
+static struct attribute_group attr_group = {
+	.attrs = attrs,
+};
+
+int igc_sysfs_init(struct igc_adapter *adapter)
+{
+	int err;
+
+	err = sysfs_create_group(&adapter->pdev->dev.kobj, &attr_group);
+	if (err) {
+		netdev_err(adapter->netdev,
+			   "Failed to create sysfs attribute group.\n");
+	}
+
+	return err;
+}
+
+void igc_sysfs_exit(struct igc_adapter *adapter)
+{
+	sysfs_remove_group(&adapter->pdev->dev.kobj, &attr_group);
+}
diff --git a/drivers/net/ethernet/intel/igc/igc_sysfs.h b/drivers/net/ethernet/intel/igc/igc_sysfs.h
new file mode 100644
index 000000000000..b074ad4bc63a
--- /dev/null
+++ b/drivers/net/ethernet/intel/igc/igc_sysfs.h
@@ -0,0 +1,10 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) 2024 Intel Corporation */
+
+#ifndef _IGC_SYSFS_H_
+#define _IGC_SYSFS_H_
+
+int igc_sysfs_init(struct igc_adapter *adapter);
+void igc_sysfs_exit(struct igc_adapter *adapter);
+
+#endif /* _IGC_SYSFS_H_ */
-- 
2.34.1