accel/qaic: Add fifo queued debugfs

When debugging functional issues with workload input processing, it is
useful to know if requests are backing up in the fifo, or perhaps
getting stuck elsewhere. To answer the question of how many requests are
in the fifo, implement a "queued" debugfs entry per-dbc that returns the
number of pending requests when read.

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/20240322175730.3855440-4-quic_jhugo@quicinc.com

3 files changed, 41 insertions, 0 deletions

diff --git a/drivers/accel/qaic/qaic.h b/drivers/accel/qaic/qaic.h
index 03d9c9fbffb3..02561b6cecc6 100644
--- a/drivers/accel/qaic/qaic.h
+++ b/drivers/accel/qaic/qaic.h
@@ -288,6 +288,7 @@ int disable_dbc(struct qaic_device *qdev, u32 dbc_id, struct qaic_user *usr);
 void enable_dbc(struct qaic_device *qdev, u32 dbc_id, struct qaic_user *usr);
 void wakeup_dbc(struct qaic_device *qdev, u32 dbc_id);
 void release_dbc(struct qaic_device *qdev, u32 dbc_id);
+void qaic_data_get_fifo_info(struct dma_bridge_chan *dbc, u32 *head, u32 *tail);
 
 void wake_all_cntl(struct qaic_device *qdev);
 void qaic_dev_reset_clean_local_state(struct qaic_device *qdev);
diff --git a/drivers/accel/qaic/qaic_data.c b/drivers/accel/qaic/qaic_data.c
index 2459fe4a3f95..e86e71c1cdd8 100644
--- a/drivers/accel/qaic/qaic_data.c
+++ b/drivers/accel/qaic/qaic_data.c
@@ -1981,3 +1981,12 @@ void release_dbc(struct qaic_device *qdev, u32 dbc_id)
 	dbc->in_use = false;
 	wake_up(&dbc->dbc_release);
 }
+
+void qaic_data_get_fifo_info(struct dma_bridge_chan *dbc, u32 *head, u32 *tail)
+{
+	if (!dbc || !head || !tail)
+		return;
+
+	*head = readl(dbc->dbc_base + REQHP_OFF);
+	*tail = readl(dbc->dbc_base + REQTP_OFF);
+}
diff --git a/drivers/accel/qaic/qaic_debugfs.c b/drivers/accel/qaic/qaic_debugfs.c
index b362960941d7..20b653d99e52 100644
--- a/drivers/accel/qaic/qaic_debugfs.c
+++ b/drivers/accel/qaic/qaic_debugfs.c
@@ -98,6 +98,36 @@ static const struct file_operations fifo_size_fops = {
 	.release = single_release,
 };
 
+static int read_dbc_queued(struct seq_file *s, void *unused)
+{
+	struct dma_bridge_chan *dbc = s->private;
+	u32 tail = 0, head = 0;
+
+	qaic_data_get_fifo_info(dbc, &head, &tail);
+
+	if (head == U32_MAX || tail == U32_MAX)
+		seq_printf(s, "%u\n", 0);
+	else if (head > tail)
+		seq_printf(s, "%u\n", dbc->nelem - head + tail);
+	else
+		seq_printf(s, "%u\n", tail - head);
+
+	return 0;
+}
+
+static int queued_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, read_dbc_queued, inode->i_private);
+}
+
+static const struct file_operations queued_fops = {
+	.owner = THIS_MODULE,
+	.open = queued_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;
@@ -117,6 +147,7 @@ void qaic_debugfs_init(struct qaic_drm_device *qddev)
 		snprintf(name, QAIC_DBC_DIR_NAME, "dbc%03u", i);
 		debugfs_dir = debugfs_create_dir(name, debugfs_root);
 		debugfs_create_file("fifo_size", 0400, debugfs_dir, &qdev->dbc[i], &fifo_size_fops);
+		debugfs_create_file("queued", 0400, debugfs_dir, &qdev->dbc[i], &queued_fops);
 	}
 }