ASoC: SOF: mtrace: rework mtrace timestamp setting

The original timestamp is built base on windows epoch time which is not
fit for Linux system and difficult to be used for kernel debugging. This
patch adopts syslog timestamp so that we can simply use dmesg to check
the timestamp between fw and kernel.

Signed-off-by: Rander Wang <[email protected]>

sound/soc/sof/ipc4-mtrace.c

@@ -4,6 +4,7 @@
 
 #include <linux/debugfs.h>
 #include <linux/sched/signal.h>
+#include <linux/sched/clock.h>
 #include <sound/sof/ipc4/header.h>
 #include "sof-priv.h"
 #include "ipc4-priv.h"
@@ -411,8 +412,9 @@ static int ipc4_mtrace_enable(struct snd_sof_dev *sdev)
 	struct sof_mtrace_priv *priv = sdev->fw_trace_data;
 	const struct sof_ipc_ops *iops = sdev->ipc->ops;
 	struct sof_ipc4_msg msg;
+	u64 send_time, reply_time;
+	u64 fw_receive_latency;
 	u64 system_time;
-	ktime_t kt;
 	int ret;
 
 	if (priv->mtrace_state != SOF_MTRACE_DISABLED)
@@ -424,9 +426,19 @@ static int ipc4_mtrace_enable(struct snd_sof_dev *sdev)
 	msg.primary |= SOF_IPC4_MOD_INSTANCE(SOF_IPC4_MOD_INIT_BASEFW_INSTANCE_ID);
 	msg.extension = SOF_IPC4_MOD_EXT_MSG_PARAM_ID(SOF_IPC4_FW_PARAM_SYSTEM_TIME);
 
-	/* The system time is in usec, UTC, epoch is 1601-01-01 00:00:00 */
-	kt = ktime_add_us(ktime_get_real(), FW_EPOCH_DELTA * USEC_PER_SEC);
-	system_time = ktime_to_us(kt);
+	/* do calibration to get the latency beween timestamp generation and fw processing */
+	send_time = local_clock();
+	msg.data_size = sizeof(system_time);
+	msg.data_ptr = &system_time;
+	/* get system time from fw */
+	ret = iops->set_get_data(sdev, &msg, msg.data_size, false);
+	if (ret)
+		return ret;
+	reply_time = local_clock();
+	fw_receive_latency = (reply_time - send_time) / 2;
+
+	/* The system time is in usec and aligned with syslog */
+	system_time =(local_clock() + fw_receive_latency) / 1000;
 	msg.data_size = sizeof(system_time);
 	msg.data_ptr = &system_time;
 	ret = iops->set_get_data(sdev, &msg, msg.data_size, true);