cxgb4: Add support to enable logging of firmware mailbox commands

Add new /sys/kernel/debug/ support to dump a firmware mailbox command
issued and replies for debugging purpose.

Based on original work by Casey Leedom <leedom@chelsio.com>
Signed-off-by: Hariprasad Shenai <hariprasad@chelsio.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/ethernet/chelsio/cxgb4/cxgb4.h

@@ -359,6 +359,34 @@ struct sge_idma_monitor_state {
 	unsigned int idma_warn[2];	/* time to warning in HZ */
 };
 
+/* Firmware Mailbox Command/Reply log.  All values are in Host-Endian format.
+ * The access and execute times are signed in order to accommodate negative
+ * error returns.
+ */
+struct mbox_cmd {
+	u64 cmd[MBOX_LEN / 8];		/* a Firmware Mailbox Command/Reply */
+	u64 timestamp;			/* OS-dependent timestamp */
+	u32 seqno;			/* sequence number */
+	s16 access;			/* time (ms) to access mailbox */
+	s16 execute;			/* time (ms) to execute */
+};
+
+struct mbox_cmd_log {
+	unsigned int size;		/* number of entries in the log */
+	unsigned int cursor;		/* next position in the log to write */
+	u32 seqno;			/* next sequence number */
+	/* variable length mailbox command log starts here */
+};
+
+/* Given a pointer to a Firmware Mailbox Command Log and a log entry index,
+ * return a pointer to the specified entry.
+ */
+static inline struct mbox_cmd *mbox_cmd_log_entry(struct mbox_cmd_log *log,
+						  unsigned int entry_idx)
+{
+	return &((struct mbox_cmd *)&(log)[1])[entry_idx];
+}
+
 #include "t4fw_api.h"
 
 #define FW_VERSION(chip) ( \
@@ -780,6 +808,10 @@ struct adapter {
 	struct work_struct db_drop_task;
 	bool tid_release_task_busy;
 
+	/* support for mailbox command/reply logging */
+#define T4_OS_LOG_MBOX_CMDS 256
+	struct mbox_cmd_log *mbox_log;
+
 	struct dentry *debugfs_root;
 	bool use_bd;     /* Use SGE Back Door intfc for reading SGE Contexts */
 	bool trace_rss;	/* 1 implies that different RSS flit per filter is

drivers/net/ethernet/chelsio/cxgb4/cxgb4_debugfs.c

@@ -1152,6 +1152,104 @@ static const struct file_operations devlog_fops = {
 	.release = seq_release_private
 };
 
+/* Show Firmware Mailbox Command/Reply Log
+ *
+ * Note that we don't do any locking when dumping the Firmware Mailbox Log so
+ * it's possible that we can catch things during a log update and therefore
+ * see partially corrupted log entries.  But it's probably Good Enough(tm).
+ * If we ever decide that we want to make sure that we're dumping a coherent
+ * log, we'd need to perform locking in the mailbox logging and in
+ * mboxlog_open() where we'd need to grab the entire mailbox log in one go
+ * like we do for the Firmware Device Log.
+ */
+static int mboxlog_show(struct seq_file *seq, void *v)
+{
+	struct adapter *adapter = seq->private;
+	struct mbox_cmd_log *log = adapter->mbox_log;
+	struct mbox_cmd *entry;
+	int entry_idx, i;
+
+	if (v == SEQ_START_TOKEN) {
+		seq_printf(seq,
+			   "%10s  %15s  %5s  %5s  %s\n",
+			   "Seq#", "Tstamp", "Atime", "Etime",
+			   "Command/Reply");
+		return 0;
+	}
+
+	entry_idx = log->cursor + ((uintptr_t)v - 2);
+	if (entry_idx >= log->size)
+		entry_idx -= log->size;
+	entry = mbox_cmd_log_entry(log, entry_idx);
+
+	/* skip over unused entries */
+	if (entry->timestamp == 0)
+		return 0;
+
+	seq_printf(seq, "%10u  %15llu  %5d  %5d",
+		   entry->seqno, entry->timestamp,
+		   entry->access, entry->execute);
+	for (i = 0; i < MBOX_LEN / 8; i++) {
+		u64 flit = entry->cmd[i];
+		u32 hi = (u32)(flit >> 32);
+		u32 lo = (u32)flit;
+
+		seq_printf(seq, "  %08x %08x", hi, lo);
+	}
+	seq_puts(seq, "\n");
+	return 0;
+}
+
+static inline void *mboxlog_get_idx(struct seq_file *seq, loff_t pos)
+{
+	struct adapter *adapter = seq->private;
+	struct mbox_cmd_log *log = adapter->mbox_log;
+
+	return ((pos <= log->size) ? (void *)(uintptr_t)(pos + 1) : NULL);
+}
+
+static void *mboxlog_start(struct seq_file *seq, loff_t *pos)
+{
+	return *pos ? mboxlog_get_idx(seq, *pos) : SEQ_START_TOKEN;
+}
+
+static void *mboxlog_next(struct seq_file *seq, void *v, loff_t *pos)
+{
+	++*pos;
+	return mboxlog_get_idx(seq, *pos);
+}
+
+static void mboxlog_stop(struct seq_file *seq, void *v)
+{
+}
+
+static const struct seq_operations mboxlog_seq_ops = {
+	.start = mboxlog_start,
+	.next  = mboxlog_next,
+	.stop  = mboxlog_stop,
+	.show  = mboxlog_show
+};
+
+static int mboxlog_open(struct inode *inode, struct file *file)
+{
+	int res = seq_open(file, &mboxlog_seq_ops);
+
+	if (!res) {
+		struct seq_file *seq = file->private_data;
+
+		seq->private = inode->i_private;
+	}
+	return res;
+}
+
+static const struct file_operations mboxlog_fops = {
+	.owner   = THIS_MODULE,
+	.open    = mboxlog_open,
+	.read    = seq_read,
+	.llseek  = seq_lseek,
+	.release = seq_release,
+};
+
 static int mbox_show(struct seq_file *seq, void *v)
 {
 	static const char * const owner[] = { "none", "FW", "driver",
@@ -3129,6 +3227,7 @@ int t4_setup_debugfs(struct adapter *adap)
 		{ "cim_qcfg", &cim_qcfg_fops, S_IRUSR, 0 },
 		{ "clk", &clk_debugfs_fops, S_IRUSR, 0 },
 		{ "devlog", &devlog_fops, S_IRUSR, 0 },
+		{ "mboxlog", &mboxlog_fops, S_IRUSR, 0 },
 		{ "mbox0", &mbox_debugfs_fops, S_IRUSR | S_IWUSR, 0 },
 		{ "mbox1", &mbox_debugfs_fops, S_IRUSR | S_IWUSR, 1 },
 		{ "mbox2", &mbox_debugfs_fops, S_IRUSR | S_IWUSR, 2 },

drivers/net/ethernet/chelsio/cxgb4/cxgb4_main.c

@@ -4909,6 +4909,16 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 		goto out_free_adapter;
 	}
 
+	adapter->mbox_log = kzalloc(sizeof(*adapter->mbox_log) +
+				    (sizeof(struct mbox_cmd) *
+				     T4_OS_LOG_MBOX_CMDS),
+				    GFP_KERNEL);
+	if (!adapter->mbox_log) {
+		err = -ENOMEM;
+		goto out_free_adapter;
+	}
+	adapter->mbox_log->size = T4_OS_LOG_MBOX_CMDS;
+
 	/* PCI device has been enabled */
 	adapter->flags |= DEV_ENABLED;
 
@@ -5167,6 +5177,7 @@ static int init_one(struct pci_dev *pdev, const struct pci_device_id *ent)
 	if (adapter->workq)
 		destroy_workqueue(adapter->workq);
 
+	kfree(adapter->mbox_log);
 	kfree(adapter);
  out_unmap_bar0:
 	iounmap(regs);
@@ -5233,6 +5244,7 @@ static void remove_one(struct pci_dev *pdev)
 			adapter->flags &= ~DEV_ENABLED;
 		}
 		pci_release_regions(pdev);
+		kfree(adapter->mbox_log);
 		synchronize_rcu();
 		kfree(adapter);
 	} else

drivers/net/ethernet/chelsio/cxgb4/t4_hw.c

@@ -224,18 +224,34 @@ static void fw_asrt(struct adapter *adap, u32 mbox_addr)
 		  be32_to_cpu(asrt.u.assert.x), be32_to_cpu(asrt.u.assert.y));
 }
 
-static void dump_mbox(struct adapter *adap, int mbox, u32 data_reg)
+/**
+ *	t4_record_mbox - record a Firmware Mailbox Command/Reply in the log
+ *	@adapter: the adapter
+ *	@cmd: the Firmware Mailbox Command or Reply
+ *	@size: command length in bytes
+ *	@access: the time (ms) needed to access the Firmware Mailbox
+ *	@execute: the time (ms) the command spent being executed
+ */
+static void t4_record_mbox(struct adapter *adapter,
+			   const __be64 *cmd, unsigned int size,
+			   int access, int execute)
 {
-	dev_err(adap->pdev_dev,
-		"mbox %d: %llx %llx %llx %llx %llx %llx %llx %llx\n", mbox,
-		(unsigned long long)t4_read_reg64(adap, data_reg),
-		(unsigned long long)t4_read_reg64(adap, data_reg + 8),
-		(unsigned long long)t4_read_reg64(adap, data_reg + 16),
-		(unsigned long long)t4_read_reg64(adap, data_reg + 24),
-		(unsigned long long)t4_read_reg64(adap, data_reg + 32),
-		(unsigned long long)t4_read_reg64(adap, data_reg + 40),
-		(unsigned long long)t4_read_reg64(adap, data_reg + 48),
-		(unsigned long long)t4_read_reg64(adap, data_reg + 56));
+	struct mbox_cmd_log *log = adapter->mbox_log;
+	struct mbox_cmd *entry;
+	int i;
+
+	entry = mbox_cmd_log_entry(log, log->cursor++);
+	if (log->cursor == log->size)
+		log->cursor = 0;
+
+	for (i = 0; i < size / 8; i++)
+		entry->cmd[i] = be64_to_cpu(cmd[i]);
+	while (i < MBOX_LEN / 8)
+		entry->cmd[i++] = 0;
+	entry->timestamp = jiffies;
+	entry->seqno = log->seqno++;
+	entry->access = access;
+	entry->execute = execute;
 }
 
 /**
@@ -268,12 +284,15 @@ int t4_wr_mbox_meat_timeout(struct adapter *adap, int mbox, const void *cmd,
 		1, 1, 3, 5, 10, 10, 20, 50, 100, 200
 	};
 
+	u16 access = 0;
+	u16 execute = 0;
 	u32 v;
 	u64 res;
-	int i, ms, delay_idx;
+	int i, ms, delay_idx, ret;
 	const __be64 *p = cmd;
 	u32 data_reg = PF_REG(mbox, CIM_PF_MAILBOX_DATA_A);
 	u32 ctl_reg = PF_REG(mbox, CIM_PF_MAILBOX_CTRL_A);
+	__be64 cmd_rpl[MBOX_LEN / 8];
 
 	if ((size & 15) || size > MBOX_LEN)
 		return -EINVAL;
@@ -289,9 +308,14 @@ int t4_wr_mbox_meat_timeout(struct adapter *adap, int mbox, const void *cmd,
 	for (i = 0; v == MBOX_OWNER_NONE && i < 3; i++)
 		v = MBOWNER_G(t4_read_reg(adap, ctl_reg));
 
-	if (v != MBOX_OWNER_DRV)
-		return v ? -EBUSY : -ETIMEDOUT;
+	if (v != MBOX_OWNER_DRV) {
+		ret = (v == MBOX_OWNER_FW) ? -EBUSY : -ETIMEDOUT;
+		t4_record_mbox(adap, cmd, MBOX_LEN, access, ret);
+		return ret;
+	}
 
+	/* Copy in the new mailbox command and send it on its way ... */
+	t4_record_mbox(adap, cmd, MBOX_LEN, access, 0);
 	for (i = 0; i < size; i += 8)
 		t4_write_reg64(adap, data_reg + i, be64_to_cpu(*p++));
 
@@ -317,26 +341,31 @@ int t4_wr_mbox_meat_timeout(struct adapter *adap, int mbox, const void *cmd,
 				continue;
 			}
 
-			res = t4_read_reg64(adap, data_reg);
+			get_mbox_rpl(adap, cmd_rpl, MBOX_LEN / 8, data_reg);
+			res = be64_to_cpu(cmd_rpl[0]);
+
 			if (FW_CMD_OP_G(res >> 32) == FW_DEBUG_CMD) {
 				fw_asrt(adap, data_reg);
 				res = FW_CMD_RETVAL_V(EIO);
 			} else if (rpl) {
-				get_mbox_rpl(adap, rpl, size / 8, data_reg);
+				memcpy(rpl, cmd_rpl, size);
 			}
 
-			if (FW_CMD_RETVAL_G((int)res))
-				dump_mbox(adap, mbox, data_reg);
 			t4_write_reg(adap, ctl_reg, 0);
+
+			execute = i + ms;
+			t4_record_mbox(adap, cmd_rpl,
+				       MBOX_LEN, access, execute);
 			return -FW_CMD_RETVAL_G((int)res);
 		}
 	}
 
-	dump_mbox(adap, mbox, data_reg);
+	ret = -ETIMEDOUT;
+	t4_record_mbox(adap, cmd, MBOX_LEN, access, ret);
 	dev_err(adap->pdev_dev, "command %#x in mailbox %d timed out\n",
 		*(const u8 *)cmd, mbox);
 	t4_report_fw_error(adap);
-	return -ETIMEDOUT;
+	return ret;
 }
 
 int t4_wr_mbox_meat(struct adapter *adap, int mbox, const void *cmd, int size,