[PATCH] usb: dwc3: add debugfs node to dump FIFO/Queue available space

[changbin . du]

From: "Du, Changbin" <changbin.du@xxxxxxxxx>

For DWC3 USB controller, the Global Debug Queue/FIFO Space Available
Register(GDBGFIFOSPACE) can be used to dump FIFO/Queue available space.
This can be used to check some special issues, like whether data is
successfully copied from memory to fifo when a trb is blocked.

Signed-off-by: Du, Changbin <changbin.du@xxxxxxxxx>
---
 drivers/usb/dwc3/core.h    |  5 +++++
 drivers/usb/dwc3/debugfs.c | 45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 50 insertions(+)

diff --git a/drivers/usb/dwc3/core.h b/drivers/usb/dwc3/core.h
index 6254b2f..899cf76 100644
--- a/drivers/usb/dwc3/core.h
+++ b/drivers/usb/dwc3/core.h
@@ -348,6 +348,11 @@
 #define DWC3_DSTS_LOWSPEED		(2 << 0)
 #define DWC3_DSTS_FULLSPEED1		(3 << 0)
 
+/* Global Debug Queue/FIFO Space Available Register */
+#define DWC3_GDBGFIFOSPACE_NUM(x)	(((x) << 0) & 0x1F)
+#define DWC3_GDBGFIFOSPACE_TYPE(x)	(((x) << 5) & 0xE0)
+#define DWC3_GDBGFIFOSPACE_GET_SPACE(x)	(((x) >> 16) & 0xFFFF)
+
 /* Device Generic Command Register */
 #define DWC3_DGCMD_SET_LMP		0x01
 #define DWC3_DGCMD_SET_PERIODIC_PAR	0x02
diff --git a/drivers/usb/dwc3/debugfs.c b/drivers/usb/dwc3/debugfs.c
index 9ac37fe..f9a8d9e 100644
--- a/drivers/usb/dwc3/debugfs.c
+++ b/drivers/usb/dwc3/debugfs.c
@@ -426,6 +426,45 @@ static const struct file_operations dwc3_mode_fops = {
 	.release		= single_release,
 };
 
+static int dwc3_fifo_show(struct seq_file *s, void *unused)
+{
+	struct dwc3		*dwc = s->private;
+	unsigned long		flags;
+	unsigned int		type, index;
+	const char		*name;
+	u32			reg;
+
+	static const char * const fifo_names[] = {
+		"TxFIFO", "RxFIFO", "TxReqQ", "RxReqQ", "RxInfoQ",
+		"DescFetchQ", "EventQ", "ProtocolStatusQ"};
+	spin_lock_irqsave(&dwc->lock, flags);
+	for (type = 0; type < 8; type++) {
+		name = fifo_names[type];
+		for (index = 0; index < 32; index++) {
+			dwc3_writel(dwc->regs, DWC3_GDBGFIFOSPACE,
+				DWC3_GDBGFIFOSPACE_NUM(index) |
+				DWC3_GDBGFIFOSPACE_TYPE(type));
+			reg = dwc3_readl(dwc->regs, DWC3_GDBGFIFOSPACE);
+			seq_printf(s, "%s%02d = %d\n", name, index,
+				DWC3_GDBGFIFOSPACE_GET_SPACE(reg));
+		}
+	}
+	spin_unlock_irqrestore(&dwc->lock, flags);
+	return 0;
+}
+
+static int dwc3_fifo_open(struct inode *inode, struct file *file)
+{
+	return single_open(file, dwc3_fifo_show, inode->i_private);
+}
+
+static const struct file_operations dwc3_fifo_fops = {
+	.open			= dwc3_fifo_open,
+	.read			= seq_read,
+	.llseek			= seq_lseek,
+	.release		= single_release,
+};
+
 static int dwc3_testmode_show(struct seq_file *s, void *unused)
 {
 	struct dwc3		*dwc = s->private;
@@ -648,6 +687,12 @@ int dwc3_debugfs_init(struct dwc3 *dwc)
 		goto err1;
 	}
 
+	file = debugfs_create_file("fifo", S_IRUGO, root, dwc, &dwc3_fifo_fops);
+	if (!file) {
+		ret = -ENOMEM;
+		goto err1;
+	}
+
 	if (IS_ENABLED(CONFIG_USB_DWC3_DUAL_ROLE)) {
 		file = debugfs_create_file("mode", S_IRUGO | S_IWUSR, root,
 				dwc, &dwc3_mode_fops);
-- 
2.5.0