[PATCH v6 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 | 35 +++++++++++++++++++++++++++++
 1 file changed, 35 insertions(+)

diff --git a/drivers/usb/host/xhci-pci-renesas.c b/drivers/usb/host/xhci-pci-renesas.c
index fe95487ca888..be2e7eff492f 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>
@@ -229,6 +230,9 @@ static int renesas_fw_verify(struct pci_dev *dev,
 
 	return 0;
 }
+
+static void debugfs_init(struct pci_dev *pdev);
+
 static int renesas_check_rom_state(struct pci_dev *pdev)
 {
 	const struct renesas_fw_entry *entry;
@@ -252,6 +256,7 @@ static int renesas_check_rom_state(struct pci_dev *pdev)
 		if (version == entry->expected_version) {
 			dev_dbg(&pdev->dev, "Detected valid ROM version..\n");
 			valid_version = true;
+			debugfs_init(pdev);
 		}
 	}
 	if (valid_version == false)
@@ -536,6 +541,34 @@ 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_download_rom(struct pci_dev *pdev,
 				 const u32 *fw, size_t step)
 {
@@ -889,6 +922,8 @@ static int renesas_xhci_pci_probe(struct pci_dev *dev,
 
 static void renesas_xhci_pci_remove(struct pci_dev *dev)
 {
+	debugfs_exit();
+
 	if (renesas_fw_alive_check(dev)) {
 		/*
 		 * bail out early, if this was a renesas device w/o FW.
-- 
2.24.1