ASoC: SOF: Add DSP firmware trace event support

Add a trace event buffer that can be used by userspace to read DSP runtime
trace events alongside bespoke trace data in realtime for firmware debug.

Signed-off-by: Liam Girdwood <liam.r.girdwood@linux.intel.com>

sound/soc/sof/sof-priv.h

@@ -365,6 +365,7 @@ struct snd_sof_dev {
 	wait_queue_head_t trace_sleep;
 	u32 host_offset;
 	bool dtrace_is_enabled;
+	bool dtrace_error;
 
 	/* PM */
 	bool restore_kcontrols; /* restore kcontrols upon resume */

sound/soc/sof/trace.c

@@ -0,0 +1,306 @@
+// SPDX-License-Identifier: (GPL-2.0 OR BSD-3-Clause)
+//
+// This file is provided under a dual BSD/GPLv2 license.  When using or
+// redistributing this file, you may do so under either license.
+//
+// Copyright(c) 2018 Intel Corporation. All rights reserved.
+//
+// Author: Liam Girdwood <liam.r.girdwood@linux.intel.com>
+//         Yan Wang <yan.wan@linux.intel.com>
+//
+
+#include <linux/delay.h>
+#include <linux/fs.h>
+#include <linux/slab.h>
+#include <linux/sched/signal.h>
+#include <linux/time.h>
+#include <linux/device.h>
+#include <linux/interrupt.h>
+#include <linux/module.h>
+#include <linux/dma-mapping.h>
+#include <linux/platform_device.h>
+#include <linux/firmware.h>
+#include <linux/debugfs.h>
+#include <uapi/sound/sof-ipc.h>
+#include <uapi/sound/sof-fw.h>
+#include "sof-priv.h"
+#include "ops.h"
+
+static size_t sof_wait_trace_avail(struct snd_sof_dev *sdev,
+				   loff_t pos, size_t buffer_size)
+{
+	wait_queue_entry_t wait;
+
+	/*
+	 * If host offset is less than local pos, it means write pointer of
+	 * host DMA buffer has been wrapped. We should output the trace data
+	 * at the end of host DMA buffer at first.
+	 */
+	if (sdev->host_offset < pos)
+		return buffer_size - pos;
+
+	/* If there is available trace data now, it is unnecessary to wait. */
+	if (sdev->host_offset > pos)
+		return sdev->host_offset - pos;
+
+	/* wait for available trace data from FW */
+	init_waitqueue_entry(&wait, current);
+	set_current_state(TASK_INTERRUPTIBLE);
+	add_wait_queue(&sdev->trace_sleep, &wait);
+
+	if (signal_pending(current)) {
+		remove_wait_queue(&sdev->trace_sleep, &wait);
+		goto out;
+	}
+
+	/* set timeout to max value, no error code */
+	schedule_timeout(MAX_SCHEDULE_TIMEOUT);
+	remove_wait_queue(&sdev->trace_sleep, &wait);
+
+out:
+	/* return bytes available for copy */
+	if (sdev->host_offset < pos)
+		return buffer_size - pos;
+	else
+		return sdev->host_offset - pos;
+}
+
+static ssize_t sof_dfsentry_trace_read(struct file *file, char __user *buffer,
+				       size_t count, loff_t *ppos)
+{
+	struct snd_sof_dfsentry_buf *dfse = file->private_data;
+	struct snd_sof_dev *sdev = dfse->sdev;
+	unsigned long rem;
+	loff_t lpos = *ppos;
+	size_t avail, buffer_size = dfse->size;
+	u64 lpos_64;
+
+	/* make sure we know about any failures on the DSP side */
+	sdev->dtrace_error = false;
+
+	/* check pos and count */
+	if (lpos < 0)
+		return -EINVAL;
+	if (!count)
+		return 0;
+
+	/* check for buffer wrap and count overflow */
+	lpos_64 = lpos;
+	lpos = do_div(lpos_64, buffer_size);
+
+	if (count > buffer_size - lpos)
+		count = buffer_size - lpos;
+
+	/* get available count based on current host offset */
+	avail = sof_wait_trace_avail(sdev, lpos, buffer_size);
+	if (sdev->dtrace_error) {
+		dev_err(sdev->dev, "error: trace IO error\n");
+		return -EIO;
+	}
+
+	/* make sure count is <= avail */
+	count = avail > count ? count : avail;
+
+	/* copy available trace data to debugfs */
+	rem = copy_to_user(buffer, dfse->buf + lpos, count);
+	if (rem == count)
+		return -EFAULT;
+
+	*ppos += count;
+
+	/* move debugfs reading position */
+	return count;
+}
+
+static const struct file_operations sof_dfs_trace_fops = {
+	.open = simple_open,
+	.read = sof_dfsentry_trace_read,
+	.llseek = default_llseek,
+};
+
+static int trace_debugfs_create(struct snd_sof_dev *sdev)
+{
+	struct snd_sof_dfsentry_buf *dfse;
+
+	if (!sdev)
+		return -EINVAL;
+
+	dfse = kzalloc(sizeof(*dfse), GFP_KERNEL);
+	if (!dfse)
+		return -ENOMEM;
+
+	dfse->buf = sdev->dmatb.area;
+	dfse->size = sdev->dmatb.bytes;
+	dfse->sdev = sdev;
+
+	dfse->dfsentry = debugfs_create_file("trace", 0444, sdev->debugfs_root,
+					     dfse, &sof_dfs_trace_fops);
+	if (!dfse->dfsentry) {
+		dev_err(sdev->dev,
+			"error: cannot create debugfs entry for trace\n");
+		kfree(dfse);
+		return -ENODEV;
+	}
+
+	return 0;
+}
+
+int snd_sof_init_trace_ipc(struct snd_sof_dev *sdev)
+{
+	struct sof_ipc_dma_trace_params params;
+	struct sof_ipc_reply ipc_reply;
+	int ret;
+
+	if (sdev->dtrace_is_enabled)
+		return -EINVAL;
+
+	/* set IPC parameters */
+	params.hdr.size = sizeof(params);
+	params.hdr.cmd = SOF_IPC_GLB_TRACE_MSG | SOF_IPC_TRACE_DMA_PARAMS;
+	params.buffer.phy_addr = sdev->dmatp.addr;
+	params.buffer.size = sdev->dmatb.bytes;
+	params.buffer.offset = 0;
+	params.buffer.pages = sdev->dma_trace_pages;
+
+	init_waitqueue_head(&sdev->trace_sleep);
+	sdev->host_offset = 0;
+
+	ret = snd_sof_dma_trace_init(sdev, &params.stream_tag);
+	if (ret < 0) {
+		dev_err(sdev->dev,
+			"error: fail in snd_sof_dma_trace_init %d\n", ret);
+		return ret;
+	}
+	dev_dbg(sdev->dev, "stream_tag: %d\n", params.stream_tag);
+
+	/* send IPC to the DSP */
+	ret = sof_ipc_tx_message(sdev->ipc,
+				 params.hdr.cmd, &params, sizeof(params),
+				 &ipc_reply, sizeof(ipc_reply));
+	if (ret < 0) {
+		dev_err(sdev->dev,
+			"error: can't set params for DMA for trace %d\n", ret);
+		return ret;
+	}
+
+	ret = snd_sof_dma_trace_trigger(sdev, SNDRV_PCM_TRIGGER_START);
+	if (ret < 0) {
+		dev_err(sdev->dev,
+			"error: snd_sof_dma_trace_trigger: start: %d\n", ret);
+		return ret;
+	}
+
+	sdev->dtrace_is_enabled = true;
+
+	return 0;
+}
+
+int snd_sof_init_trace(struct snd_sof_dev *sdev)
+{
+	int ret;
+
+	/* set false before start initialization */
+	sdev->dtrace_is_enabled = false;
+
+	/* allocate trace page table buffer */
+	ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV, sdev->parent,
+				  PAGE_SIZE, &sdev->dmatp);
+	if (ret < 0) {
+		dev_err(sdev->dev,
+			"error: can't alloc page table for trace %d\n", ret);
+		return ret;
+	}
+
+	/* allocate trace data buffer */
+	ret = snd_dma_alloc_pages(SNDRV_DMA_TYPE_DEV_SG, sdev->parent,
+				  DMA_BUF_SIZE_FOR_TRACE, &sdev->dmatb);
+	if (ret < 0) {
+		dev_err(sdev->dev,
+			"error: can't alloc buffer for trace %d\n", ret);
+		goto page_err;
+	}
+
+	/* craete compressed page table for audio firmware */
+	ret = snd_sof_create_page_table(sdev, &sdev->dmatb, sdev->dmatp.area,
+					sdev->dmatb.bytes);
+	if (ret < 0)
+		goto table_err;
+
+	sdev->dma_trace_pages = ret;
+	dev_dbg(sdev->dev, "dma_trace_pages: %d\n", sdev->dma_trace_pages);
+
+	if (sdev->first_boot) {
+		ret = trace_debugfs_create(sdev);
+		if (ret < 0)
+			goto table_err;
+	}
+
+	ret = snd_sof_init_trace_ipc(sdev);
+	if (ret < 0)
+		goto table_err;
+
+	return 0;
+table_err:
+	snd_dma_free_pages(&sdev->dmatb);
+page_err:
+	snd_dma_free_pages(&sdev->dmatp);
+	return ret;
+}
+EXPORT_SYMBOL(snd_sof_init_trace);
+
+int snd_sof_trace_update_pos(struct snd_sof_dev *sdev,
+			     struct sof_ipc_dma_trace_posn *posn)
+{
+	if (sdev->dtrace_is_enabled && sdev->host_offset != posn->host_offset) {
+		sdev->host_offset = posn->host_offset;
+		wake_up(&sdev->trace_sleep);
+	}
+
+	if (posn->overflow != 0)
+		dev_err(sdev->dev,
+			"error: DSP trace buffer overflow %u bytes. Total messages %d\n",
+			posn->overflow, posn->messages);
+
+	return 0;
+}
+
+/* an error has occurred within the DSP that prevents further trace */
+void snd_sof_trace_notify_for_error(struct snd_sof_dev *sdev)
+{
+	if (sdev->dtrace_is_enabled) {
+		dev_err(sdev->dev, "error: waking up any trace sleepers\n");
+		sdev->dtrace_error = true;
+		wake_up(&sdev->trace_sleep);
+	}
+}
+EXPORT_SYMBOL(snd_sof_trace_notify_for_error);
+
+void snd_sof_release_trace(struct snd_sof_dev *sdev)
+{
+	int ret;
+
+	if (!sdev->dtrace_is_enabled)
+		return;
+
+	ret = snd_sof_dma_trace_trigger(sdev, SNDRV_PCM_TRIGGER_STOP);
+	if (ret < 0)
+		dev_err(sdev->dev,
+			"error: snd_sof_dma_trace_trigger: stop: %d\n", ret);
+
+	ret = snd_sof_dma_trace_release(sdev);
+	if (ret < 0)
+		dev_err(sdev->dev,
+			"error: fail in snd_sof_dma_trace_release %d\n", ret);
+
+	sdev->dtrace_is_enabled = false;
+}
+EXPORT_SYMBOL(snd_sof_release_trace);
+
+void snd_sof_free_trace(struct snd_sof_dev *sdev)
+{
+	snd_sof_release_trace(sdev);
+
+	snd_dma_free_pages(&sdev->dmatb);
+	snd_dma_free_pages(&sdev->dmatp);
+}
+EXPORT_SYMBOL(snd_sof_free_trace);