eth: fbnic: Create ring buffer for firmware logs

When enabled, firmware may send logs messages which are specific to the
device and not the host. Create a ring buffer to store these messages
which are read by a user through DebugFS. Buffer access is protected by
a spinlock.

Signed-off-by: Lee Trager <lee@trager.us>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Link: https://patch.msgid.link/20250702192207.697368-4-lee@trager.us
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/meta/fbnic/Makefile b/drivers/net/ethernet/meta/fbnic/Makefile
index 0dbc634adb4b8152e8e359968ad1d2d59fc98d69..15e8ff649615918ddd60977448492ec065d29676 100644 (file)
--- a/drivers/net/ethernet/meta/fbnic/Makefile
+++ b/drivers/net/ethernet/meta/fbnic/Makefile
@@ -12,6 +12,7 @@ fbnic-y := fbnic_csr.o \
           fbnic_devlink.o \
           fbnic_ethtool.o \
           fbnic_fw.o \
+          fbnic_fw_log.o \
           fbnic_hw_stats.o \
           fbnic_hwmon.o \
           fbnic_irq.o \

diff --git a/drivers/net/ethernet/meta/fbnic/fbnic.h b/drivers/net/ethernet/meta/fbnic/fbnic.h
index 65815d4f379e43abd71f73fc3d9df74595da6232..c376e06880c9c5dfa7603eaa9b5ff9a0ae4d0204 100644 (file)
--- a/drivers/net/ethernet/meta/fbnic/fbnic.h
+++ b/drivers/net/ethernet/meta/fbnic/fbnic.h
@@ -12,6 +12,7 @@
 
 #include "fbnic_csr.h"
 #include "fbnic_fw.h"
+#include "fbnic_fw_log.h"
 #include "fbnic_hw_stats.h"
 #include "fbnic_mac.h"
 #include "fbnic_rpc.h"
@@ -85,6 +86,8 @@ struct fbnic_dev {
 
        /* Lock protecting access to hw_stats */
        spinlock_t hw_stats_lock;
+
+       struct fbnic_fw_log fw_log;
 };
 
 /* Reserve entry 0 in the MSI-X "others" array until we have filled all

diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_fw_log.c b/drivers/net/ethernet/meta/fbnic/fbnic_fw_log.c
new file mode 100644 (file)
index 0000000..caedbe7
--- /dev/null
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_fw_log.c
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) Meta Platforms, Inc. and affiliates. */
+
+#include <linux/spinlock.h>
+#include <linux/vmalloc.h>
+
+#include "fbnic.h"
+#include "fbnic_fw.h"
+#include "fbnic_fw_log.h"
+
+int fbnic_fw_log_init(struct fbnic_dev *fbd)
+{
+       struct fbnic_fw_log *log = &fbd->fw_log;
+       void *data;
+
+       if (WARN_ON_ONCE(fbnic_fw_log_ready(fbd)))
+               return -EEXIST;
+
+       data = vmalloc(FBNIC_FW_LOG_SIZE);
+       if (!data)
+               return -ENOMEM;
+
+       spin_lock_init(&fbd->fw_log.lock);
+       INIT_LIST_HEAD(&log->entries);
+       log->size = FBNIC_FW_LOG_SIZE;
+       log->data_start = data;
+       log->data_end = data + FBNIC_FW_LOG_SIZE;
+
+       return 0;
+}
+
+void fbnic_fw_log_free(struct fbnic_dev *fbd)
+{
+       struct fbnic_fw_log *log = &fbd->fw_log;
+
+       if (!fbnic_fw_log_ready(fbd))
+               return;
+
+       INIT_LIST_HEAD(&log->entries);
+       log->size = 0;
+       vfree(log->data_start);
+       log->data_start = NULL;
+       log->data_end = NULL;
+}
+
+int fbnic_fw_log_write(struct fbnic_dev *fbd, u64 index, u32 timestamp,
+                      char *msg)
+{
+       struct fbnic_fw_log_entry *entry, *head, *tail, *next;
+       struct fbnic_fw_log *log = &fbd->fw_log;
+       size_t msg_len = strlen(msg) + 1;
+       unsigned long flags;
+       void *entry_end;
+
+       if (!fbnic_fw_log_ready(fbd)) {
+               dev_err(fbd->dev, "Firmware sent log entry without being requested!\n");
+               return -ENOSPC;
+       }
+
+       spin_lock_irqsave(&log->lock, flags);
+
+       if (list_empty(&log->entries)) {
+               entry = log->data_start;
+       } else {
+               head = list_first_entry(&log->entries, typeof(*head), list);
+               entry = (struct fbnic_fw_log_entry *)&head->msg[head->len + 1];
+               entry = PTR_ALIGN(entry, 8);
+       }
+
+       entry_end = &entry->msg[msg_len + 1];
+
+       /* We've reached the end of the buffer, wrap around */
+       if (entry_end > log->data_end) {
+               entry = log->data_start;
+               entry_end = &entry->msg[msg_len + 1];
+       }
+
+       /* Make room for entry by removing from tail. */
+       list_for_each_entry_safe_reverse(tail, next, &log->entries, list) {
+               if (entry <= tail && entry_end > (void *)tail)
+                       list_del(&tail->list);
+               else
+                       break;
+       }
+
+       entry->index = index;
+       entry->timestamp = timestamp;
+       entry->len = msg_len;
+       strscpy(entry->msg, msg, entry->len);
+       list_add(&entry->list, &log->entries);
+
+       spin_unlock_irqrestore(&log->lock, flags);
+
+       return 0;
+}

diff --git a/drivers/net/ethernet/meta/fbnic/fbnic_fw_log.h b/drivers/net/ethernet/meta/fbnic/fbnic_fw_log.h
new file mode 100644 (file)
index 0000000..881ee29
--- /dev/null
+++ b/drivers/net/ethernet/meta/fbnic/fbnic_fw_log.h
@@ -0,0 +1,43 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/* Copyright (c) Meta Platforms, Inc. and affiliates. */
+
+#ifndef _FBNIC_FW_LOG_H_
+#define _FBNIC_FW_LOG_H_
+
+#include <linux/spinlock.h>
+#include <linux/types.h>
+
+/* A 512K log buffer was chosen fairly arbitrarily */
+#define FBNIC_FW_LOG_SIZE      (512 * 1024) /* bytes */
+
+/* Firmware log output is prepended with log index followed by a timestamp.
+ * The timestamp is similar to Zephyr's format DD:HH:MM:SS.MMM
+ */
+#define FBNIC_FW_LOG_FMT       "[%5lld] [%02ld:%02ld:%02ld:%02ld.%03ld] %s\n"
+
+struct fbnic_dev;
+
+struct fbnic_fw_log_entry {
+       struct list_head        list;
+       u64                     index;
+       u32                     timestamp;
+       u16                     len;
+       char                    msg[] __counted_by(len);
+};
+
+struct fbnic_fw_log {
+       void                    *data_start;
+       void                    *data_end;
+       size_t                  size;
+       struct list_head        entries;
+       /* Spin lock for accessing or modifying entries */
+       spinlock_t              lock;
+};
+
+#define fbnic_fw_log_ready(_fbd)       (!!(_fbd)->fw_log.data_start)
+
+int fbnic_fw_log_init(struct fbnic_dev *fbd);
+void fbnic_fw_log_free(struct fbnic_dev *fbd);
+int fbnic_fw_log_write(struct fbnic_dev *fbd, u64 index, u32 timestamp,
+                      char *msg);
+#endif /* _FBNIC_FW_LOG_H_ */