accel/qaic: Add support for periodic timesync

Device and Host have a time synchronization mechanism that happens once
during boot when device is in SBL mode. After that, in mission-mode there
is no timesync. In an experiment after continuous operation, device time
drifted w.r.t. host by approximately 3 seconds per day. This drift leads
to mismatch in timestamp of device and Host logs. To correct this
implement periodic timesync in driver. This timesync is carried out via
QAIC_TIMESYNC_PERIODIC MHI channel.

Signed-off-by: Ajit Pal Singh <quic_ajitpals@quicinc.com>
Signed-off-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@quicinc.com>
Reviewed-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Carl Vanderlip <quic_carlv@quicinc.com>
Reviewed-by: Pranjal Ramajor Asha Kanojiya <quic_pkanojiy@quicinc.com>
Signed-off-by: Jeffrey Hugo <quic_jhugo@quicinc.com>
Reviewed-by: Stanislaw Gruszka <stanislaw.gruszka@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231016170114.5446-2-quic_jhugo@quicinc.com

5 files changed, 296 insertions, 1 deletions

diff --git a/drivers/accel/qaic/Makefile b/drivers/accel/qaic/Makefile
index 2418418f7a50..3f7f6dfde7f2 100644
--- a/drivers/accel/qaic/Makefile
+++ b/drivers/accel/qaic/Makefile
@@ -9,4 +9,5 @@ qaic-y := \
 	mhi_controller.o \
 	qaic_control.o \
 	qaic_data.o \
-	qaic_drv.o
+	qaic_drv.o \
+	qaic_timesync.o
diff --git a/drivers/accel/qaic/mhi_controller.c b/drivers/accel/qaic/mhi_controller.c
index 41be3626587d..705898777ec5 100644
--- a/drivers/accel/qaic/mhi_controller.c
+++ b/drivers/accel/qaic/mhi_controller.c
@@ -373,6 +373,38 @@ static struct mhi_channel_config aic100_channels[] = {
 		.auto_queue = false,
 		.wake_capable = false,
 	},
+	{
+		.name = "QAIC_TIMESYNC_PERIODIC",
+		.num = 22,
+		.num_elements = 32,
+		.local_elements = 0,
+		.event_ring = 0,
+		.dir = DMA_TO_DEVICE,
+		.ee_mask = MHI_CH_EE_AMSS,
+		.pollcfg = 0,
+		.doorbell = MHI_DB_BRST_DISABLE,
+		.lpm_notify = false,
+		.offload_channel = false,
+		.doorbell_mode_switch = false,
+		.auto_queue = false,
+		.wake_capable = false,
+	},
+	{
+		.num = 23,
+		.name = "QAIC_TIMESYNC_PERIODIC",
+		.num_elements = 32,
+		.local_elements = 0,
+		.event_ring = 0,
+		.dir = DMA_FROM_DEVICE,
+		.ee_mask = MHI_CH_EE_AMSS,
+		.pollcfg = 0,
+		.doorbell = MHI_DB_BRST_DISABLE,
+		.lpm_notify = false,
+		.offload_channel = false,
+		.doorbell_mode_switch = false,
+		.auto_queue = false,
+		.wake_capable = false,
+	},
 };
 
 static struct mhi_event_config aic100_events[] = {
diff --git a/drivers/accel/qaic/qaic_drv.c b/drivers/accel/qaic/qaic_drv.c
index 5eba5f03d3bf..08d940d3da46 100644
--- a/drivers/accel/qaic/qaic_drv.c
+++ b/drivers/accel/qaic/qaic_drv.c
@@ -27,6 +27,7 @@
 
 #include "mhi_controller.h"
 #include "qaic.h"
+#include "qaic_timesync.h"
 
 MODULE_IMPORT_NS(DMA_BUF);
 
@@ -599,6 +600,10 @@ static int __init qaic_init(void)
 		goto free_pci;
 	}
 
+	ret = qaic_timesync_init();
+	if (ret)
+		pr_debug("qaic: qaic_timesync_init failed %d\n", ret);
+
 	return 0;
 
 free_pci:
@@ -624,6 +629,7 @@ static void __exit qaic_exit(void)
 	 * reinitializing the link_up state after the cleanup is done.
 	 */
 	link_up = true;
+	qaic_timesync_deinit();
 	mhi_driver_unregister(&qaic_mhi_driver);
 	pci_unregister_driver(&qaic_pci_driver);
 }
diff --git a/drivers/accel/qaic/qaic_timesync.c b/drivers/accel/qaic/qaic_timesync.c
new file mode 100644
index 000000000000..769250272c21
--- /dev/null
+++ b/drivers/accel/qaic/qaic_timesync.c
@@ -0,0 +1,245 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/* Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved. */
+
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/math64.h>
+#include <linux/mhi.h>
+#include <linux/mod_devicetable.h>
+#include <linux/module.h>
+#include <linux/time64.h>
+#include <linux/timer.h>
+
+#include "qaic.h"
+#include "qaic_timesync.h"
+
+#define QTIMER_REG_OFFSET			0xa28
+#define QAIC_TIMESYNC_SIGNATURE			0x55aa
+#define QAIC_CONV_QTIMER_TO_US(qtimer)		(mul_u64_u32_div(qtimer, 10, 192))
+
+static unsigned int timesync_delay_ms = 1000; /* 1 sec default */
+module_param(timesync_delay_ms, uint, 0600);
+MODULE_PARM_DESC(timesync_delay_ms, "Delay in ms between two consecutive timesync operations");
+
+enum qts_msg_type {
+	QAIC_TS_SYNC_REQ = 1,
+	QAIC_TS_ACK_TO_HOST,
+	QAIC_TS_MSG_TYPE_MAX
+};
+
+/**
+ * struct qts_hdr - Timesync message header structure.
+ * @signature: Unique signature to identify the timesync message.
+ * @reserved_1: Reserved for future use.
+ * @reserved_2: Reserved for future use.
+ * @msg_type: sub-type of the timesync message.
+ * @reserved_3: Reserved for future use.
+ */
+struct qts_hdr {
+	__le16	signature;
+	__le16	reserved_1;
+	u8	reserved_2;
+	u8	msg_type;
+	__le16	reserved_3;
+} __packed;
+
+/**
+ * struct qts_timeval - Structure to carry time information.
+ * @tv_sec: Seconds part of the time.
+ * @tv_usec: uS (microseconds) part of the time.
+ */
+struct qts_timeval {
+	__le64	tv_sec;
+	__le64	tv_usec;
+} __packed;
+
+/**
+ * struct qts_host_time_sync_msg_data - Structure to denote the timesync message.
+ * @header: Header of the timesync message.
+ * @data: Time information.
+ */
+struct qts_host_time_sync_msg_data {
+	struct	qts_hdr header;
+	struct	qts_timeval data;
+} __packed;
+
+/**
+ * struct mqts_dev - MHI QAIC Timesync Control device.
+ * @qdev: Pointer to the root device struct driven by QAIC driver.
+ * @mhi_dev: Pointer to associated MHI device.
+ * @timer: Timer handle used for timesync.
+ * @qtimer_addr: Device QTimer register pointer.
+ * @buff_in_use: atomic variable to track if the sync_msg buffer is in use.
+ * @dev: Device pointer to qdev->pdev->dev stored for easy access.
+ * @sync_msg: Buffer used to send timesync message over MHI.
+ */
+struct mqts_dev {
+	struct qaic_device *qdev;
+	struct mhi_device *mhi_dev;
+	struct timer_list timer;
+	void __iomem *qtimer_addr;
+	atomic_t buff_in_use;
+	struct device *dev;
+	struct qts_host_time_sync_msg_data *sync_msg;
+};
+
+#ifdef readq
+static u64 read_qtimer(const volatile void __iomem *addr)
+{
+	return readq(addr);
+}
+#else
+static u64 read_qtimer(const volatile void __iomem *addr)
+{
+	u64 low, high;
+
+	low = readl(addr);
+	high = readl(addr + sizeof(u32));
+	return low | (high << 32);
+}
+#endif
+
+static void qaic_timesync_ul_xfer_cb(struct mhi_device *mhi_dev, struct mhi_result *mhi_result)
+{
+	struct mqts_dev *mqtsdev = dev_get_drvdata(&mhi_dev->dev);
+
+	dev_dbg(mqtsdev->dev, "%s status: %d xfer_len: %zu\n", __func__,
+		mhi_result->transaction_status, mhi_result->bytes_xferd);
+
+	atomic_set(&mqtsdev->buff_in_use, 0);
+}
+
+static void qaic_timesync_dl_xfer_cb(struct mhi_device *mhi_dev, struct mhi_result *mhi_result)
+{
+	struct mqts_dev *mqtsdev = dev_get_drvdata(&mhi_dev->dev);
+
+	dev_err(mqtsdev->dev, "%s no data expected on dl channel\n", __func__);
+}
+
+static void qaic_timesync_timer(struct timer_list *t)
+{
+	struct mqts_dev *mqtsdev = from_timer(mqtsdev, t, timer);
+	struct qts_host_time_sync_msg_data *sync_msg;
+	u64 device_qtimer_us;
+	u64 device_qtimer;
+	u64 host_time_us;
+	u64 offset_us;
+	u64 host_sec;
+	int ret;
+
+	if (atomic_read(&mqtsdev->buff_in_use)) {
+		dev_dbg(mqtsdev->dev, "%s buffer not free, schedule next cycle\n", __func__);
+		goto mod_timer;
+	}
+	atomic_set(&mqtsdev->buff_in_use, 1);
+
+	sync_msg = mqtsdev->sync_msg;
+	sync_msg->header.signature = cpu_to_le16(QAIC_TIMESYNC_SIGNATURE);
+	sync_msg->header.msg_type = QAIC_TS_SYNC_REQ;
+	/* Read host UTC time and convert to uS*/
+	host_time_us = div_u64(ktime_get_real_ns(), NSEC_PER_USEC);
+	device_qtimer = read_qtimer(mqtsdev->qtimer_addr);
+	device_qtimer_us = QAIC_CONV_QTIMER_TO_US(device_qtimer);
+	/* Offset between host UTC and device time */
+	offset_us = host_time_us - device_qtimer_us;
+
+	host_sec = div_u64(offset_us, USEC_PER_SEC);
+	sync_msg->data.tv_usec = cpu_to_le64(offset_us - host_sec * USEC_PER_SEC);
+	sync_msg->data.tv_sec = cpu_to_le64(host_sec);
+	ret = mhi_queue_buf(mqtsdev->mhi_dev, DMA_TO_DEVICE, sync_msg, sizeof(*sync_msg), MHI_EOT);
+	if (ret && (ret != -EAGAIN)) {
+		dev_err(mqtsdev->dev, "%s unable to queue to mhi:%d\n", __func__, ret);
+		return;
+	} else if (ret == -EAGAIN) {
+		atomic_set(&mqtsdev->buff_in_use, 0);
+	}
+
+mod_timer:
+	ret = mod_timer(t, jiffies + msecs_to_jiffies(timesync_delay_ms));
+	if (ret)
+		dev_err(mqtsdev->dev, "%s mod_timer error:%d\n", __func__, ret);
+}
+
+static int qaic_timesync_probe(struct mhi_device *mhi_dev, const struct mhi_device_id *id)
+{
+	struct qaic_device *qdev = pci_get_drvdata(to_pci_dev(mhi_dev->mhi_cntrl->cntrl_dev));
+	struct mqts_dev *mqtsdev;
+	struct timer_list *timer;
+	int ret;
+
+	mqtsdev = kzalloc(sizeof(*mqtsdev), GFP_KERNEL);
+	if (!mqtsdev) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	timer = &mqtsdev->timer;
+	mqtsdev->mhi_dev = mhi_dev;
+	mqtsdev->qdev = qdev;
+	mqtsdev->dev = &qdev->pdev->dev;
+
+	mqtsdev->sync_msg = kzalloc(sizeof(*mqtsdev->sync_msg), GFP_KERNEL);
+	if (!mqtsdev->sync_msg) {
+		ret = -ENOMEM;
+		goto free_mqts_dev;
+	}
+	atomic_set(&mqtsdev->buff_in_use, 0);
+
+	ret = mhi_prepare_for_transfer(mhi_dev);
+	if (ret)
+		goto free_sync_msg;
+
+	/* Qtimer register pointer */
+	mqtsdev->qtimer_addr = qdev->bar_0 + QTIMER_REG_OFFSET;
+	timer_setup(timer, qaic_timesync_timer, 0);
+	timer->expires = jiffies + msecs_to_jiffies(timesync_delay_ms);
+	add_timer(timer);
+	dev_set_drvdata(&mhi_dev->dev, mqtsdev);
+
+	return 0;
+
+free_sync_msg:
+	kfree(mqtsdev->sync_msg);
+free_mqts_dev:
+	kfree(mqtsdev);
+out:
+	return ret;
+};
+
+static void qaic_timesync_remove(struct mhi_device *mhi_dev)
+{
+	struct mqts_dev *mqtsdev = dev_get_drvdata(&mhi_dev->dev);
+
+	del_timer_sync(&mqtsdev->timer);
+	mhi_unprepare_from_transfer(mqtsdev->mhi_dev);
+	kfree(mqtsdev->sync_msg);
+	kfree(mqtsdev);
+}
+
+static const struct mhi_device_id qaic_timesync_match_table[] = {
+	{ .chan = "QAIC_TIMESYNC_PERIODIC"},
+	{},
+};
+
+MODULE_DEVICE_TABLE(mhi, qaic_timesync_match_table);
+
+static struct mhi_driver qaic_timesync_driver = {
+	.id_table = qaic_timesync_match_table,
+	.remove = qaic_timesync_remove,
+	.probe = qaic_timesync_probe,
+	.ul_xfer_cb = qaic_timesync_ul_xfer_cb,
+	.dl_xfer_cb = qaic_timesync_dl_xfer_cb,
+	.driver = {
+		.name = "qaic_timesync_periodic",
+	},
+};
+
+int qaic_timesync_init(void)
+{
+	return mhi_driver_register(&qaic_timesync_driver);
+}
+
+void qaic_timesync_deinit(void)
+{
+	mhi_driver_unregister(&qaic_timesync_driver);
+}
diff --git a/drivers/accel/qaic/qaic_timesync.h b/drivers/accel/qaic/qaic_timesync.h
new file mode 100644
index 000000000000..851b7acd43bb
--- /dev/null
+++ b/drivers/accel/qaic/qaic_timesync.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0-only
+ *
+ * Copyright (c) 2023 Qualcomm Innovation Center, Inc. All rights reserved.
+ */
+
+#ifndef __QAIC_TIMESYNC_H__
+#define __QAIC_TIMESYNC_H__
+
+int qaic_timesync_init(void);
+void qaic_timesync_deinit(void);
+#endif /* __QAIC_TIMESYNC_H__ */