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eth: fbnic: Create ring buffer for firmware logs

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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>
This commit is contained in:
Lee Trager
2025-07-02 12:12:09 -07:00
committed by Jakub Kicinski
parent e48f6620ee
commit c2b93d6bec
4 changed files with 142 additions and 0 deletions
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1
drivers/net/ethernet/meta/fbnic/Makefile
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@@ -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 \

3
drivers/net/ethernet/meta/fbnic/fbnic.h
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@@ -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

95
drivers/net/ethernet/meta/fbnic/fbnic_fw_log.c Normal file
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@@ -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;
}

43
drivers/net/ethernet/meta/fbnic/fbnic_fw_log.h Normal file
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@@ -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_ */