[PATCH v13 5/5] usb: xhci: provide a debugfs hook for erasing rom

[Vinod Koul <vkoul@kernel.org>]

run "echo 1 > /sys/kernel/debug/renesas-usb/rom_erase" to erase
firmware when driver is loaded.

Subsequent init of driver shall reload the firmware

Signed-off-by: Vinod Koul <vkoul@kernel.org>
---
 drivers/usb/host/xhci-pci-renesas.c | 33 +++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/drivers/usb/host/xhci-pci-renesas.c b/drivers/usb/host/xhci-pci-renesas.c
index f7d2445d30ec..fa32ec352dc8 100644
--- a/drivers/usb/host/xhci-pci-renesas.c
+++ b/drivers/usb/host/xhci-pci-renesas.c
@@ -2,6 +2,7 @@
 /* Copyright (C) 2019-2020 Linaro Limited */
 
 #include <linux/acpi.h>
+#include <linux/debugfs.h>
 #include <linux/firmware.h>
 #include <linux/module.h>
 #include <linux/pci.h>
@@ -170,6 +171,8 @@ static int renesas_fw_verify(const void *fw_data,
 	return 0;
 }
 
+static void debugfs_init(struct pci_dev *pdev);
+
 static bool renesas_check_rom(struct pci_dev *pdev)
 {
 	u16 rom_status;
@@ -183,6 +186,7 @@ static bool renesas_check_rom(struct pci_dev *pdev)
 	rom_status &= RENESAS_ROM_STATUS_ROM_EXISTS;
 	if (rom_status) {
 		dev_dbg(&pdev->dev, "External ROM exists\n");
+		debugfs_init(pdev);
 		return true; /* External ROM exists */
 	}
 
@@ -449,6 +453,34 @@ static void renesas_rom_erase(struct pci_dev *pdev)
 	dev_dbg(&pdev->dev, "ROM Erase... Done success\n");
 }
 
+static int debugfs_rom_erase(void *data, u64 value)
+{
+	struct pci_dev *pdev = data;
+
+	if (value == 1) {
+		dev_dbg(&pdev->dev, "Userspace requested ROM erase\n");
+		renesas_rom_erase(pdev);
+		return 0;
+	}
+	return -EINVAL;
+}
+DEFINE_DEBUGFS_ATTRIBUTE(rom_erase_ops, NULL, debugfs_rom_erase, "%llu\n");
+
+static struct dentry *debugfs_root;
+
+static void debugfs_init(struct pci_dev *pdev)
+{
+	debugfs_root = debugfs_create_dir("renesas_usb", NULL);
+
+	debugfs_create_file("rom_erase", 0200, debugfs_root,
+			    pdev, &rom_erase_ops);
+}
+
+static void debugfs_exit(void)
+{
+	debugfs_remove_recursive(debugfs_root);
+}
+
 static bool renesas_setup_rom(struct pci_dev *pdev, const struct firmware *fw)
 {
 	const u32 *fw_data = (const u32 *)fw->data;
@@ -639,6 +671,7 @@ EXPORT_SYMBOL_GPL(renesas_xhci_check_request_fw);
 
 void renesas_xhci_pci_exit(struct pci_dev *dev)
 {
+	debugfs_exit();
 }
 EXPORT_SYMBOL_GPL(renesas_xhci_pci_exit);
 
-- 
2.25.4