[PATCH v3 1/2] usb: gadget: goku_udc: move debug output to debugfs

[Cheng Lingfei]

goku_udc exposes diagnostic state through /proc/driver/udc. The single
global proc entry collides when more than one controller is probed and
triggers a proc registration warning.

The data is intended only for debugging and is not a userspace ABI. Move it
under the USB debugfs root and use the PCI device name for a per-device
directory. Create the file only after the UDC has been registered.

Suggested-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
Link: https://lore.kernel.org/2026082616-glue-atlas-0cfd@gregkh
Assisted-by: Codex:gpt-5.6
Signed-off-by: Cheng Lingfei <chenglingfei@xxxxxxxxxxx>
---
 drivers/usb/gadget/udc/goku_udc.c | 47 +++++++++++++++++++++++++++------------
 drivers/usb/gadget/udc/goku_udc.h |  5 ++++-
 2 files changed, 37 insertions(+), 15 deletions(-)

diff --git a/drivers/usb/gadget/udc/goku_udc.c b/drivers/usb/gadget/udc/goku_udc.c
index ac2a984c2f87..5ad8633f522b 100644
--- a/drivers/usb/gadget/udc/goku_udc.c
+++ b/drivers/usb/gadget/udc/goku_udc.c
@@ -20,6 +20,7 @@
 // #define	VERBOSE		/* extra debug messages (success too) */
 // #define	USB_TRACE	/* packet-level success messages */
 
+#include <linux/debugfs.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/pci.h>
@@ -30,9 +31,9 @@
 #include <linux/timer.h>
 #include <linux/list.h>
 #include <linux/interrupt.h>
-#include <linux/proc_fs.h>
 #include <linux/seq_file.h>
 #include <linux/device.h>
+#include <linux/usb.h>
 #include <linux/usb/ch9.h>
 #include <linux/usb/gadget.h>
 #include <linux/prefetch.h>
@@ -1050,9 +1051,7 @@ static inline const char *dmastr(void)
 		return "(dma IN)";
 }
 
-#ifdef CONFIG_USB_GADGET_DEBUG_FILES
-
-static const char proc_node_name [] = "driver/udc";
+#ifdef CONFIG_USB_GADGET_DEBUG_FS
 
 #define FOURBITS "%s%s%s%s"
 #define EIGHTBITS FOURBITS FOURBITS
@@ -1134,7 +1133,7 @@ static const char *udc_ep_status(u32 status)
 	return "?";
 }
 
-static int udc_proc_read(struct seq_file *m, void *v)
+static int goku_debugfs_show(struct seq_file *m, void *v)
 {
 	struct goku_udc			*dev = m->private;
 	struct goku_udc_regs __iomem	*regs = dev->regs;
@@ -1246,7 +1245,33 @@ static int udc_proc_read(struct seq_file *m, void *v)
 	local_irq_restore(flags);
 	return 0;
 }
-#endif	/* CONFIG_USB_GADGET_DEBUG_FILES */
+DEFINE_SHOW_ATTRIBUTE(goku_debugfs);
+
+static void goku_debugfs_create(struct goku_udc *dev)
+{
+	dev->debugfs_root =
+		debugfs_create_dir(dev_name(&dev->pdev->dev), usb_debug_root);
+	debugfs_create_file("goku_udc_state", 0400, dev->debugfs_root, dev,
+			    &goku_debugfs_fops);
+}
+
+static void goku_debugfs_remove(struct goku_udc *dev)
+{
+	debugfs_remove_recursive(dev->debugfs_root);
+	dev->debugfs_root = NULL;
+}
+
+#else
+
+static inline void goku_debugfs_create(struct goku_udc *dev)
+{
+}
+
+static inline void goku_debugfs_remove(struct goku_udc *dev)
+{
+}
+
+#endif	/* CONFIG_USB_GADGET_DEBUG_FS */
 
 /*-------------------------------------------------------------------------*/
 
@@ -1718,9 +1743,7 @@ static void goku_remove(struct pci_dev *pdev)
 
 	BUG_ON(dev->driver);
 
-#ifdef CONFIG_USB_GADGET_DEBUG_FILES
-	remove_proc_entry(proc_node_name, NULL);
-#endif
+	goku_debugfs_remove(dev);
 	if (dev->regs)
 		udc_reset(dev);
 	if (dev->got_irq)
@@ -1813,15 +1836,11 @@ static int goku_probe(struct pci_dev *pdev, const struct pci_device_id *id)
 	if (use_dma)
 		pci_set_master(pdev);
 
-
-#ifdef CONFIG_USB_GADGET_DEBUG_FILES
-	proc_create_single_data(proc_node_name, 0, NULL, udc_proc_read, dev);
-#endif
-
 	retval = usb_add_gadget_udc_release(&pdev->dev, &dev->gadget,
 			gadget_release);
 	if (retval)
 		goto err;
+	goku_debugfs_create(dev);
 
 	return 0;
 
diff --git a/drivers/usb/gadget/udc/goku_udc.h b/drivers/usb/gadget/udc/goku_udc.h
index 70023d401079..4885b1dae928 100644
--- a/drivers/usb/gadget/udc/goku_udc.h
+++ b/drivers/usb/gadget/udc/goku_udc.h
@@ -249,6 +249,10 @@ struct goku_udc {
 					configured:1,
 					enabled:1;
 
+#ifdef CONFIG_USB_GADGET_DEBUG_FS
+	struct dentry			*debugfs_root;
+#endif
+
 	/* pci state used to access those endpoints */
 	struct pci_dev			*pdev;
 	struct goku_udc_regs __iomem	*regs;
@@ -286,4 +290,3 @@ struct goku_udc {
 	xprintk(dev , KERN_WARNING , fmt , ## args)
 #define INFO(dev,fmt,args...) \
 	xprintk(dev , KERN_INFO , fmt , ## args)
-

-- 
2.53.0