scsi: ufs: add trace event for ufs commands

Use the ftrace infrastructure to conditionally trace ufs command events.
New trace event is created, which samples the following ufs command data:
- device name
- optional identification string
- task tag
- doorbell register
- number of transfer bytes
- interrupt status register
- request start LBA
- command opcode

Currently we only fully trace read(10) and write(10) commands.
All other commands which pass through ufshcd_send_command() will be
printed with "-1" in the lba and transfer_len fields.

Usage:
	echo 1 > /sys/kernel/debug/tracing/events/ufs/enable
	cat /sys/kernel/debug/tracing/trace_pipe

Signed-off-by: Lee Susman <lsusman@codeaurora.org>
Signed-off-by: Subhash Jadavani <subhashj@codeaurora.org>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

drivers/scsi/ufs/ufshcd.c

@@ -293,6 +293,41 @@ static inline void ufshcd_remove_non_printable(char *val)
 		*val = ' ';
 }
 
+static void ufshcd_add_command_trace(struct ufs_hba *hba,
+		unsigned int tag, const char *str)
+{
+	sector_t lba = -1;
+	u8 opcode = 0;
+	u32 intr, doorbell;
+	struct ufshcd_lrb *lrbp;
+	int transfer_len = -1;
+
+	if (!trace_ufshcd_command_enabled())
+		return;
+
+	lrbp = &hba->lrb[tag];
+
+	if (lrbp->cmd) { /* data phase exists */
+		opcode = (u8)(*lrbp->cmd->cmnd);
+		if ((opcode == READ_10) || (opcode == WRITE_10)) {
+			/*
+			 * Currently we only fully trace read(10) and write(10)
+			 * commands
+			 */
+			if (lrbp->cmd->request && lrbp->cmd->request->bio)
+				lba =
+				  lrbp->cmd->request->bio->bi_iter.bi_sector;
+			transfer_len = be32_to_cpu(
+				lrbp->ucd_req_ptr->sc.exp_data_transfer_len);
+		}
+	}
+
+	intr = ufshcd_readl(hba, REG_INTERRUPT_STATUS);
+	doorbell = ufshcd_readl(hba, REG_UTP_TRANSFER_REQ_DOOR_BELL);
+	trace_ufshcd_command(dev_name(hba->dev), str, tag,
+				doorbell, transfer_len, intr, lba, opcode);
+}
+
 static void ufshcd_print_host_regs(struct ufs_hba *hba)
 {
 	/*
@@ -1166,6 +1201,7 @@ void ufshcd_send_command(struct ufs_hba *hba, unsigned int task_tag)
 	ufshcd_writel(hba, 1 << task_tag, REG_UTP_TRANSFER_REQ_DOOR_BELL);
 	/* Make sure that doorbell is committed immediately */
 	wmb();
+	ufshcd_add_command_trace(hba, task_tag, "send");
 }
 
 /**
@@ -3955,6 +3991,7 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba,
 		lrbp = &hba->lrb[index];
 		cmd = lrbp->cmd;
 		if (cmd) {
+			ufshcd_add_command_trace(hba, index, "complete");
 			result = ufshcd_transfer_rsp_status(hba, lrbp);
 			scsi_dma_unmap(cmd);
 			cmd->result = result;
@@ -3966,8 +4003,11 @@ static void __ufshcd_transfer_req_compl(struct ufs_hba *hba,
 			__ufshcd_release(hba);
 		} else if (lrbp->command_type == UTP_CMD_TYPE_DEV_MANAGE ||
 			lrbp->command_type == UTP_CMD_TYPE_UFS_STORAGE) {
-			if (hba->dev_cmd.complete)
+			if (hba->dev_cmd.complete) {
+				ufshcd_add_command_trace(hba, index,
+						"dev_complete");
 				complete(hba->dev_cmd.complete);
+			}
 		}
 	}
 

include/trace/events/ufs.h

@@ -219,6 +219,44 @@ DEFINE_EVENT(ufshcd_template, ufshcd_init,
 	     TP_PROTO(const char *dev_name, int err, s64 usecs,
 		      int dev_state, int link_state),
 	     TP_ARGS(dev_name, err, usecs, dev_state, link_state));
+
+TRACE_EVENT(ufshcd_command,
+	TP_PROTO(const char *dev_name, const char *str, unsigned int tag,
+			u32 doorbell, int transfer_len, u32 intr, u64 lba,
+			u8 opcode),
+
+	TP_ARGS(dev_name, str, tag, doorbell, transfer_len, intr, lba, opcode),
+
+	TP_STRUCT__entry(
+		__string(dev_name, dev_name)
+		__string(str, str)
+		__field(unsigned int, tag)
+		__field(u32, doorbell)
+		__field(int, transfer_len)
+		__field(u32, intr)
+		__field(u64, lba)
+		__field(u8, opcode)
+	),
+
+	TP_fast_assign(
+		__assign_str(dev_name, dev_name);
+		__assign_str(str, str);
+		__entry->tag = tag;
+		__entry->doorbell = doorbell;
+		__entry->transfer_len = transfer_len;
+		__entry->intr = intr;
+		__entry->lba = lba;
+		__entry->opcode = opcode;
+	),
+
+	TP_printk(
+		"%s: %s: tag: %u, DB: 0x%x, size: %d, IS: %u, LBA: %llu, opcode: 0x%x",
+		__get_str(str), __get_str(dev_name), __entry->tag,
+		__entry->doorbell, __entry->transfer_len,
+		__entry->intr, __entry->lba, (u32)__entry->opcode
+	)
+);
+
 #endif /* if !defined(_TRACE_UFS_H) || defined(TRACE_HEADER_MULTI_READ) */
 
 /* This part must be outside protection */