bnxt_en: add debugfs support for DIM

This adds debugfs support for bnxt_en with the purpose of allowing users
to examine the current DIM profile in use for each receive queue.  This
was instrumental in debugging issues found with DIM and ensuring that
the profiles we expect to use are the profiles being used.
Signed-off-by: Andy Gospodarek <gospo@broadcom.com>
Signed-off-by: Michael Chan <michael.chan@broadcom.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/broadcom/bnxt/Makefile

@@ -2,3 +2,4 @@ obj-$(CONFIG_BNXT) += bnxt_en.o
 
 bnxt_en-y := bnxt.o bnxt_sriov.o bnxt_ethtool.o bnxt_dcb.o bnxt_ulp.o bnxt_xdp.o bnxt_vfr.o bnxt_devlink.o bnxt_dim.o
 bnxt_en-$(CONFIG_BNXT_FLOWER_OFFLOAD) += bnxt_tc.o
+bnxt_en-$(CONFIG_DEBUG_FS) += bnxt_debugfs.o

drivers/net/ethernet/broadcom/bnxt/bnxt.c

@@ -62,6 +62,7 @@
 #include "bnxt_vfr.h"
 #include "bnxt_tc.h"
 #include "bnxt_devlink.h"
+#include "bnxt_debugfs.h"
 
 #define BNXT_TX_TIMEOUT		(5 * HZ)
 
@@ -6870,6 +6871,7 @@ static int __bnxt_open_nic(struct bnxt *bp, bool irq_re_init, bool link_re_init)
 	}
 
 	bnxt_enable_napi(bp);
+	bnxt_debug_dev_init(bp);
 
 	rc = bnxt_init_nic(bp, irq_re_init);
 	if (rc) {
@@ -6902,6 +6904,7 @@ static int __bnxt_open_nic(struct bnxt *bp, bool irq_re_init, bool link_re_init)
 	return 0;
 
 open_err:
+	bnxt_debug_dev_exit(bp);
 	bnxt_disable_napi(bp);
 	bnxt_del_napi(bp);
 
@@ -6995,6 +6998,7 @@ static void __bnxt_close_nic(struct bnxt *bp, bool irq_re_init,
 
 	/* TODO CHIMP_FW: Link/PHY related cleanup if (link_re_init) */
 
+	bnxt_debug_dev_exit(bp);
 	bnxt_disable_napi(bp);
 	del_timer_sync(&bp->timer);
 	bnxt_free_skbs(bp);
@@ -9071,6 +9075,7 @@ static struct pci_driver bnxt_pci_driver = {
 
 static int __init bnxt_init(void)
 {
+	bnxt_debug_init();
 	return pci_register_driver(&bnxt_pci_driver);
 }
 
@@ -9079,6 +9084,7 @@ static void __exit bnxt_exit(void)
 	pci_unregister_driver(&bnxt_pci_driver);
 	if (bnxt_pf_wq)
 		destroy_workqueue(bnxt_pf_wq);
+	bnxt_debug_exit();
 }
 
 module_init(bnxt_init);

drivers/net/ethernet/broadcom/bnxt/bnxt.h

@@ -1391,6 +1391,8 @@ struct bnxt {
 	u16			*cfa_code_map; /* cfa_code -> vf_idx map */
 	u8			switch_id[8];
 	struct bnxt_tc_info	*tc_info;
+	struct dentry		*debugfs_pdev;
+	struct dentry		*debugfs_dim;
 };
 
 #define BNXT_RX_STATS_OFFSET(counter)			\

drivers/net/ethernet/broadcom/bnxt/bnxt_debugfs.c

+/* Broadcom NetXtreme-C/E network driver.
+ *
+ * Copyright (c) 2017-2018 Broadcom Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation.
+ */
+
+#include <linux/debugfs.h>
+#include <linux/module.h>
+#include <linux/pci.h>
+#include "bnxt_hsi.h"
+#include <linux/net_dim.h>
+#include "bnxt.h"
+#include "bnxt_debugfs.h"
+
+static struct dentry *bnxt_debug_mnt;
+
+static ssize_t debugfs_dim_read(struct file *filep,
+				char __user *buffer,
+				size_t count, loff_t *ppos)
+{
+	struct net_dim *dim = filep->private_data;
+	int len;
+	char *buf;
+
+	if (*ppos)
+		return 0;
+	if (!dim)
+		return -ENODEV;
+	buf = kasprintf(GFP_KERNEL,
+			"state = %d\n" \
+			"profile_ix = %d\n" \
+			"mode = %d\n" \
+			"tune_state = %d\n" \
+			"steps_right = %d\n" \
+			"steps_left = %d\n" \
+			"tired = %d\n",
+			dim->state,
+			dim->profile_ix,
+			dim->mode,
+			dim->tune_state,
+			dim->steps_right,
+			dim->steps_left,
+			dim->tired);
+	if (!buf)
+		return -ENOMEM;
+	if (count < strlen(buf)) {
+		kfree(buf);
+		return -ENOSPC;
+	}
+	len = simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
+	kfree(buf);
+	return len;
+}
+
+static const struct file_operations debugfs_dim_fops = {
+	.owner = THIS_MODULE,
+	.open = simple_open,
+	.read = debugfs_dim_read,
+};
+
+static struct dentry *debugfs_dim_ring_init(struct net_dim *dim, int ring_idx,
+					    struct dentry *dd)
+{
+	static char qname[16];
+
+	snprintf(qname, 10, "%d", ring_idx);
+	return debugfs_create_file(qname, 0600, dd,
+				   dim, &debugfs_dim_fops);
+}
+
+void bnxt_debug_dev_init(struct bnxt *bp)
+{
+	const char *pname = pci_name(bp->pdev);
+	struct dentry *pdevf;
+	int i;
+
+	bp->debugfs_pdev = debugfs_create_dir(pname, bnxt_debug_mnt);
+	if (bp->debugfs_pdev) {
+		pdevf = debugfs_create_dir("dim", bp->debugfs_pdev);
+		if (!pdevf) {
+			pr_err("failed to create debugfs entry %s/dim\n",
+			       pname);
+			return;
+		}
+		bp->debugfs_dim = pdevf;
+		/* create files for each rx ring */
+		for (i = 0; i < bp->cp_nr_rings; i++) {
+			struct bnxt_cp_ring_info *cpr = &bp->bnapi[i]->cp_ring;
+
+			if (cpr && bp->bnapi[i]->rx_ring) {
+				pdevf = debugfs_dim_ring_init(&cpr->dim, i,
+							      bp->debugfs_dim);
+				if (!pdevf)
+					pr_err("failed to create debugfs entry %s/dim/%d\n",
+					       pname, i);
+			}
+		}
+	} else {
+		pr_err("failed to create debugfs entry %s\n", pname);
+	}
+}
+
+void bnxt_debug_dev_exit(struct bnxt *bp)
+{
+	if (bp) {
+		debugfs_remove_recursive(bp->debugfs_pdev);
+		bp->debugfs_pdev = NULL;
+	}
+}
+
+void bnxt_debug_init(void)
+{
+	bnxt_debug_mnt = debugfs_create_dir("bnxt_en", NULL);
+	if (!bnxt_debug_mnt)
+		pr_err("failed to init bnxt_en debugfs\n");
+}
+
+void bnxt_debug_exit(void)
+{
+	debugfs_remove_recursive(bnxt_debug_mnt);
+}

drivers/net/ethernet/broadcom/bnxt/bnxt_debugfs.h

+/* Broadcom NetXtreme-C/E network driver.
+ *
+ * Copyright (c) 2017-2018 Broadcom Limited
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation.
+ */
+
+#include "bnxt_hsi.h"
+#include "bnxt.h"
+
+#ifdef CONFIG_DEBUG_FS
+void bnxt_debug_init(void);
+void bnxt_debug_exit(void);
+void bnxt_debug_dev_init(struct bnxt *bp);
+void bnxt_debug_dev_exit(struct bnxt *bp);
+#else
+static inline void bnxt_debug_init(void) {}
+static inline void bnxt_debug_exit(void) {}
+static inline void bnxt_debug_dev_init(struct bnxt *bp) {}
+static inline void bnxt_debug_dev_exit(struct bnxt *bp) {}
+#endif