eth: fbnic: add basic debugfs structure

Add the usual debugfs structure:

 fbnic/
   $pci-id/
     device-fileA
     device-fileB

This patch only adds the directories, subsequent changes
will add files.

Reviewed-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Link: https://patch.msgid.link/20241115015344.757567-4-kuba@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/meta/fbnic/Makefile

@@ -8,6 +8,7 @@
 obj-$(CONFIG_FBNIC) += fbnic.o
 
 fbnic-y := fbnic_csr.o \
+	   fbnic_debugfs.o \
 	   fbnic_devlink.o \
 	   fbnic_ethtool.o \
 	   fbnic_fw.o \

drivers/net/ethernet/meta/fbnic/fbnic.h

@@ -19,6 +19,7 @@
 struct fbnic_dev {
 	struct device *dev;
 	struct net_device *netdev;
+	struct dentry *dbg_fbd;
 	struct device *hwmon;
 
 	u32 __iomem *uc_addr0;
@@ -156,6 +157,11 @@ int fbnic_alloc_irqs(struct fbnic_dev *fbd);
 void fbnic_get_fw_ver_commit_str(struct fbnic_dev *fbd, char *fw_version,
 				 const size_t str_sz);
 
+void fbnic_dbg_fbd_init(struct fbnic_dev *fbd);
+void fbnic_dbg_fbd_exit(struct fbnic_dev *fbd);
+void fbnic_dbg_init(void);
+void fbnic_dbg_exit(void);
+
 void fbnic_csr_get_regs(struct fbnic_dev *fbd, u32 *data, u32 *regs_version);
 int fbnic_csr_regs_len(struct fbnic_dev *fbd);
 

drivers/net/ethernet/meta/fbnic/fbnic_debugfs.c

@@ -0,0 +1,34 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) Meta Platforms, Inc. and affiliates. */
+
+#include <linux/debugfs.h>
+#include <linux/pci.h>
+
+#include "fbnic.h"
+
+static struct dentry *fbnic_dbg_root;
+
+void fbnic_dbg_fbd_init(struct fbnic_dev *fbd)
+{
+	struct pci_dev *pdev = to_pci_dev(fbd->dev);
+	const char *name = pci_name(pdev);
+
+	fbd->dbg_fbd = debugfs_create_dir(name, fbnic_dbg_root);
+}
+
+void fbnic_dbg_fbd_exit(struct fbnic_dev *fbd)
+{
+	debugfs_remove_recursive(fbd->dbg_fbd);
+	fbd->dbg_fbd = NULL;
+}
+
+void fbnic_dbg_init(void)
+{
+	fbnic_dbg_root = debugfs_create_dir(fbnic_driver_name, NULL);
+}
+
+void fbnic_dbg_exit(void)
+{
+	debugfs_remove_recursive(fbnic_dbg_root);
+	fbnic_dbg_root = NULL;
+}

drivers/net/ethernet/meta/fbnic/fbnic_pci.c

@@ -288,6 +288,7 @@ static int fbnic_probe(struct pci_dev *pdev, const struct pci_device_id *ent)
 	}
 
 	fbnic_devlink_register(fbd);
+	fbnic_dbg_fbd_init(fbd);
 
 	fbnic_hwmon_register(fbd);
 
@@ -355,6 +356,7 @@ static void fbnic_remove(struct pci_dev *pdev)
 	}
 
 	fbnic_hwmon_unregister(fbd);
+	fbnic_dbg_fbd_exit(fbd);
 	fbnic_devlink_unregister(fbd);
 	fbnic_fw_disable_mbx(fbd);
 	fbnic_free_irqs(fbd);
@@ -552,9 +554,13 @@ static int __init fbnic_init_module(void)
 {
 	int err;
 
+	fbnic_dbg_init();
+
 	err = pci_register_driver(&fbnic_driver);
-	if (err)
+	if (err) {
+		fbnic_dbg_exit();
 		goto out;
+	}
 
 	pr_info(DRV_SUMMARY " (%s)", fbnic_driver.name);
 out:
@@ -570,5 +576,7 @@ module_init(fbnic_init_module);
 static void __exit fbnic_exit_module(void)
 {
 	pci_unregister_driver(&fbnic_driver);
+
+	fbnic_dbg_exit();
 }
 module_exit(fbnic_exit_module);