accel/qaic: Add bootlog debugfs

During the boot process of AIC100, the bootloaders (PBL and SBL) log
messages to device RAM. During SBL, if the host opens the QAIC_LOGGING
channel, SBL will offload the contents of the log buffer to the host,
and stream any new messages that SBL logs.

This log of the boot process can be very useful for an initial triage of
any boot related issues. For example, if SBL rejects one of the runtime
firmware images for a validation failure, SBL will log a reason why.

Add the ability of the driver to open the logging channel, receive the
messages, and store them. Also define a debugfs entry called "bootlog"
by hooking into the DRM debugfs framework. When the bootlog debugfs
entry is read, the current contents of the log that the host is caching
is displayed to the user. The driver will retain the cache until it
detects that the device has rebooted.  At that point, the cache will be
freed, and the driver will wait for a new log. With this scheme, the
driver will only have a cache of the log from the current device boot.
Note that if the driver initializes a device and it is already in the
runtime state (QSM), no bootlog will be available through this mechanism
because the driver and SBL have not communicated.

Signed-off-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>
Reviewed-by: Jacek Lawrynowicz <jacek.lawrynowicz@linux.intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240322175730.3855440-2-quic_jhugo@quicinc.com

drivers/accel/qaic/Makefile

@@ -11,3 +11,5 @@ qaic-y := \
 	qaic_data.o \
 	qaic_drv.o \
 	qaic_timesync.o
+
+qaic-$(CONFIG_DEBUG_FS) += qaic_debugfs.o

drivers/accel/qaic/qaic.h

@@ -153,6 +153,14 @@ struct qaic_device {
 	struct mhi_device	*qts_ch;
 	/* Work queue for tasks related to MHI "QAIC_TIMESYNC" channel */
 	struct workqueue_struct	*qts_wq;
+	/* Head of list of page allocated by MHI bootlog device */
+	struct list_head        bootlog;
+	/* MHI bootlog channel device */
+	struct mhi_device       *bootlog_ch;
+	/* Work queue for tasks related to MHI bootlog device */
+	struct workqueue_struct *bootlog_wq;
+	/* Synchronizes access of pages in MHI bootlog device */
+	struct mutex            bootlog_mutex;
 };
 
 struct qaic_drm_device {

drivers/accel/qaic/qaic_debugfs.c

@@ -0,0 +1,272 @@
+// SPDX-License-Identifier: GPL-2.0-only
+
+/* Copyright (c) 2020, The Linux Foundation. All rights reserved. */
+/* Copyright (c) 2021-2024 Qualcomm Innovation Center, Inc. All rights reserved. */
+
+#include <linux/debugfs.h>
+#include <linux/device.h>
+#include <linux/fs.h>
+#include <linux/list.h>
+#include <linux/mhi.h>
+#include <linux/mutex.h>
+#include <linux/overflow.h>
+#include <linux/pci.h>
+#include <linux/seq_file.h>
+#include <linux/string.h>
+#include <linux/types.h>
+#include <linux/workqueue.h>
+
+#include "qaic.h"
+#include "qaic_debugfs.h"
+
+#define BOOTLOG_POOL_SIZE		16
+#define BOOTLOG_MSG_SIZE		512
+
+struct bootlog_msg {
+	/* Buffer for bootlog messages */
+	char str[BOOTLOG_MSG_SIZE];
+	/* Root struct of device, used to access device resources */
+	struct qaic_device *qdev;
+	/* Work struct to schedule work coming on QAIC_LOGGING channel */
+	struct work_struct work;
+};
+
+struct bootlog_page {
+	/* Node in list of bootlog pages maintained by root device struct */
+	struct list_head node;
+	/* Total size of the buffer that holds the bootlogs. It is PAGE_SIZE */
+	unsigned int size;
+	/* Offset for the next bootlog */
+	unsigned int offset;
+};
+
+static int bootlog_show(struct seq_file *s, void *unused)
+{
+	struct bootlog_page *page;
+	struct qaic_device *qdev;
+	void *page_end;
+	void *log;
+
+	qdev = s->private;
+	mutex_lock(&qdev->bootlog_mutex);
+	list_for_each_entry(page, &qdev->bootlog, node) {
+		log = page + 1;
+		page_end = (void *)page + page->offset;
+		while (log < page_end) {
+			seq_printf(s, "%s", (char *)log);
+			log += strlen(log) + 1;
+		}
+	}
+	mutex_unlock(&qdev->bootlog_mutex);
+
+	return 0;
+}
+
+static int bootlog_fops_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, bootlog_show, inode->i_private);
+}
+
+static const struct file_operations bootlog_fops = {
+	.owner = THIS_MODULE,
+	.open = bootlog_fops_open,
+	.read = seq_read,
+	.llseek = seq_lseek,
+	.release = single_release,
+};
+
+void qaic_debugfs_init(struct qaic_drm_device *qddev)
+{
+	struct qaic_device *qdev = qddev->qdev;
+	struct dentry *debugfs_root;
+
+	debugfs_root = to_drm(qddev)->debugfs_root;
+
+	debugfs_create_file("bootlog", 0400, debugfs_root, qdev, &bootlog_fops);
+}
+
+static struct bootlog_page *alloc_bootlog_page(struct qaic_device *qdev)
+{
+	struct bootlog_page *page;
+
+	page = (struct bootlog_page *)devm_get_free_pages(&qdev->pdev->dev, GFP_KERNEL, 0);
+	if (!page)
+		return page;
+
+	page->size = PAGE_SIZE;
+	page->offset = sizeof(*page);
+	list_add_tail(&page->node, &qdev->bootlog);
+
+	return page;
+}
+
+static int reset_bootlog(struct qaic_device *qdev)
+{
+	struct bootlog_page *page;
+	struct bootlog_page *i;
+
+	mutex_lock(&qdev->bootlog_mutex);
+	list_for_each_entry_safe(page, i, &qdev->bootlog, node) {
+		list_del(&page->node);
+		devm_free_pages(&qdev->pdev->dev, (unsigned long)page);
+	}
+
+	page = alloc_bootlog_page(qdev);
+	mutex_unlock(&qdev->bootlog_mutex);
+	if (!page)
+		return -ENOMEM;
+
+	return 0;
+}
+
+static void *bootlog_get_space(struct qaic_device *qdev, unsigned int size)
+{
+	struct bootlog_page *page;
+
+	page = list_last_entry(&qdev->bootlog, struct bootlog_page, node);
+
+	if (size_add(size, sizeof(*page)) > page->size)
+		return NULL;
+
+	if (page->offset + size > page->size) {
+		page = alloc_bootlog_page(qdev);
+		if (!page)
+			return NULL;
+	}
+
+	return (void *)page + page->offset;
+}
+
+static void bootlog_commit(struct qaic_device *qdev, unsigned int size)
+{
+	struct bootlog_page *page;
+
+	page = list_last_entry(&qdev->bootlog, struct bootlog_page, node);
+
+	page->offset += size;
+}
+
+static void bootlog_log(struct work_struct *work)
+{
+	struct bootlog_msg *msg = container_of(work, struct bootlog_msg, work);
+	unsigned int len = strlen(msg->str) + 1;
+	struct qaic_device *qdev = msg->qdev;
+	void *log;
+
+	mutex_lock(&qdev->bootlog_mutex);
+	log = bootlog_get_space(qdev, len);
+	if (log) {
+		memcpy(log, msg, len);
+		bootlog_commit(qdev, len);
+	}
+	mutex_unlock(&qdev->bootlog_mutex);
+
+	if (mhi_queue_buf(qdev->bootlog_ch, DMA_FROM_DEVICE, msg, BOOTLOG_MSG_SIZE, MHI_EOT))
+		devm_kfree(&qdev->pdev->dev, msg);
+}
+
+static int qaic_bootlog_mhi_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 bootlog_msg *msg;
+	int i, ret;
+
+	qdev->bootlog_wq = alloc_ordered_workqueue("qaic_bootlog", 0);
+	if (!qdev->bootlog_wq) {
+		ret = -ENOMEM;
+		goto out;
+	}
+
+	ret = reset_bootlog(qdev);
+	if (ret)
+		goto destroy_workqueue;
+
+	ret = mhi_prepare_for_transfer(mhi_dev);
+	if (ret)
+		goto destroy_workqueue;
+
+	for (i = 0; i < BOOTLOG_POOL_SIZE; i++) {
+		msg = devm_kzalloc(&qdev->pdev->dev, sizeof(*msg), GFP_KERNEL);
+		if (!msg) {
+			ret = -ENOMEM;
+			goto mhi_unprepare;
+		}
+
+		msg->qdev = qdev;
+		INIT_WORK(&msg->work, bootlog_log);
+
+		ret = mhi_queue_buf(mhi_dev, DMA_FROM_DEVICE, msg, BOOTLOG_MSG_SIZE, MHI_EOT);
+		if (ret)
+			goto mhi_unprepare;
+	}
+
+	dev_set_drvdata(&mhi_dev->dev, qdev);
+	qdev->bootlog_ch = mhi_dev;
+	return 0;
+
+mhi_unprepare:
+	mhi_unprepare_from_transfer(mhi_dev);
+destroy_workqueue:
+	flush_workqueue(qdev->bootlog_wq);
+	destroy_workqueue(qdev->bootlog_wq);
+out:
+	return ret;
+}
+
+static void qaic_bootlog_mhi_remove(struct mhi_device *mhi_dev)
+{
+	struct qaic_device *qdev;
+
+	qdev = dev_get_drvdata(&mhi_dev->dev);
+
+	mhi_unprepare_from_transfer(qdev->bootlog_ch);
+	flush_workqueue(qdev->bootlog_wq);
+	destroy_workqueue(qdev->bootlog_wq);
+	qdev->bootlog_ch = NULL;
+}
+
+static void qaic_bootlog_mhi_ul_xfer_cb(struct mhi_device *mhi_dev, struct mhi_result *mhi_result)
+{
+}
+
+static void qaic_bootlog_mhi_dl_xfer_cb(struct mhi_device *mhi_dev, struct mhi_result *mhi_result)
+{
+	struct qaic_device *qdev = dev_get_drvdata(&mhi_dev->dev);
+	struct bootlog_msg *msg = mhi_result->buf_addr;
+
+	if (mhi_result->transaction_status) {
+		devm_kfree(&qdev->pdev->dev, msg);
+		return;
+	}
+
+	/* Force a null at the end of the transferred string */
+	msg->str[mhi_result->bytes_xferd - 1] = 0;
+
+	queue_work(qdev->bootlog_wq, &msg->work);
+}
+
+static const struct mhi_device_id qaic_bootlog_mhi_match_table[] = {
+	{ .chan = "QAIC_LOGGING", },
+	{},
+};
+
+static struct mhi_driver qaic_bootlog_mhi_driver = {
+	.id_table = qaic_bootlog_mhi_match_table,
+	.remove = qaic_bootlog_mhi_remove,
+	.probe = qaic_bootlog_mhi_probe,
+	.ul_xfer_cb = qaic_bootlog_mhi_ul_xfer_cb,
+	.dl_xfer_cb = qaic_bootlog_mhi_dl_xfer_cb,
+	.driver = {
+		.name = "qaic_bootlog",
+	},
+};
+
+int qaic_bootlog_register(void)
+{
+	return mhi_driver_register(&qaic_bootlog_mhi_driver);
+}
+
+void qaic_bootlog_unregister(void)
+{
+	mhi_driver_unregister(&qaic_bootlog_mhi_driver);
+}

drivers/accel/qaic/qaic_debugfs.h

@@ -0,0 +1,20 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+
+/* Copyright (c) 2020, The Linux Foundation. All rights reserved. */
+/* Copyright (c) 2024 Qualcomm Innovation Center, Inc. All rights reserved. */
+
+#ifndef __QAIC_DEBUGFS_H__
+#define __QAIC_DEBUGFS_H__
+
+#include <drm/drm_file.h>
+
+#ifdef CONFIG_DEBUG_FS
+int qaic_bootlog_register(void);
+void qaic_bootlog_unregister(void);
+void qaic_debugfs_init(struct qaic_drm_device *qddev);
+#else
+int qaic_bootlog_register(void) { return 0; }
+void qaic_bootlog_unregister(void) {}
+void qaic_debugfs_init(struct qaic_drm_device *qddev) {}
+#endif /* CONFIG_DEBUG_FS */
+#endif /* __QAIC_DEBUGFS_H__ */

drivers/accel/qaic/qaic_drv.c

@@ -28,6 +28,7 @@
 
 #include "mhi_controller.h"
 #include "qaic.h"
+#include "qaic_debugfs.h"
 #include "qaic_timesync.h"
 
 MODULE_IMPORT_NS(DMA_BUF);
@@ -229,8 +230,12 @@ static int qaic_create_drm_device(struct qaic_device *qdev, s32 partition_id)
 	qddev->partition_id = partition_id;
 
 	ret = drm_dev_register(drm, 0);
-	if (ret)
+	if (ret) {
 		pci_dbg(qdev->pdev, "drm_dev_register failed %d\n", ret);
+		return ret;
+	}
+
+	qaic_debugfs_init(qddev);
 
 	return ret;
 }
@@ -380,6 +385,9 @@ static struct qaic_device *create_qdev(struct pci_dev *pdev, const struct pci_de
 	if (ret)
 		return NULL;
 	ret = drmm_mutex_init(drm, &qdev->cntl_mutex);
+	if (ret)
+		return NULL;
+	ret = drmm_mutex_init(drm, &qdev->bootlog_mutex);
 	if (ret)
 		return NULL;
 
@@ -399,6 +407,7 @@ static struct qaic_device *create_qdev(struct pci_dev *pdev, const struct pci_de
 	qddev->qdev = qdev;
 
 	INIT_LIST_HEAD(&qdev->cntl_xfer_list);
+	INIT_LIST_HEAD(&qdev->bootlog);
 	INIT_LIST_HEAD(&qddev->users);
 
 	for (i = 0; i < qdev->num_dbc; ++i) {
@@ -639,6 +648,10 @@ static int __init qaic_init(void)
 	if (ret)
 		pr_debug("qaic: qaic_timesync_init failed %d\n", ret);
 
+	ret = qaic_bootlog_register();
+	if (ret)
+		pr_debug("qaic: qaic_bootlog_register failed %d\n", ret);
+
 	return 0;
 
 free_pci:
@@ -664,6 +677,7 @@ static void __exit qaic_exit(void)
 	 * reinitializing the link_up state after the cleanup is done.
 	 */
 	link_up = true;
+	qaic_bootlog_unregister();
 	qaic_timesync_deinit();
 	mhi_driver_unregister(&qaic_mhi_driver);
 	pci_unregister_driver(&qaic_pci_driver);