[PATCH v6 01/12] usb: xhci: add sysfs file for xHCI debug port

[Lu Baolu]

This patch adds a sysfs file for users to check 1) whether the debug
capability is implemented by hardware; 2) if supported, which state
does it stay at.

With a host that supports debug port, a file named "debug_port_state"
will be created under the device sysfs directory. Reading this file
will show users the state (disabled, enabled or configured) of the
debug port.

With a host that does NOT support debug port, "debug_port_state" file
won't be created.

Signed-off-by: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
---
 .../ABI/testing/sysfs-bus-pci-drivers-xhci_hcd     | 23 ++++++++
 drivers/usb/host/Makefile                          |  2 +-
 drivers/usb/host/xhci-ext-caps.h                   |  5 ++
 drivers/usb/host/xhci-sysfs.c                      | 65 ++++++++++++++++++++++
 drivers/usb/host/xhci.c                            |  4 ++
 drivers/usb/host/xhci.h                            |  4 ++
 6 files changed, 102 insertions(+), 1 deletion(-)
 create mode 100644 Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
 create mode 100644 drivers/usb/host/xhci-sysfs.c

diff --git a/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
new file mode 100644
index 0000000..5d0a7d3
--- /dev/null
+++ b/Documentation/ABI/testing/sysfs-bus-pci-drivers-xhci_hcd
@@ -0,0 +1,23 @@
+What:		/sys/bus/pci/drivers/xhci_hcd/.../debug_port_state
+Date:		November 2015
+KernelVersion:	4.4.0
+Contact:	Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
+Description:
+		This file is designed for users to check the state of a
+		USB3 debug port. On a machine which supports USB3 debug
+		port, this file will be created. Reading this file will
+		show the state (disabled, enabled or configured) of the
+		debug port. On a machine that doesn't support USB3 debug
+		port, this file doesn't exist.
+
+		The state of a debug port could be:
+		1) disabled: The debug port is not enabled and the root
+			port has been switched to xHCI host as a normal
+			root port.
+		2) enabled: The debug port is enabled. The debug port
+			has been assigned to debug capability. The debug
+			capability is able to handle the control requests
+			defined in USB3 spec.
+		3) configured: The debug port has been enumerated by the
+			debug host as a debug device. The debug port is
+			in use now.
diff --git a/drivers/usb/host/Makefile b/drivers/usb/host/Makefile
index 65a06b4..aba2bf5 100644
--- a/drivers/usb/host/Makefile
+++ b/drivers/usb/host/Makefile
@@ -12,7 +12,7 @@ fhci-$(CONFIG_FHCI_DEBUG) += fhci-dbg.o
 
 xhci-hcd-y := xhci.o xhci-mem.o
 xhci-hcd-y += xhci-ring.o xhci-hub.o xhci-dbg.o
-xhci-hcd-y += xhci-trace.o
+xhci-hcd-y += xhci-trace.o xhci-sysfs.o
 ifneq ($(CONFIG_USB_XHCI_MTK), )
 	xhci-hcd-y += xhci-mtk-sch.o
 endif
diff --git a/drivers/usb/host/xhci-ext-caps.h b/drivers/usb/host/xhci-ext-caps.h
index 04ce6b1..c4b49c5 100644
--- a/drivers/usb/host/xhci-ext-caps.h
+++ b/drivers/usb/host/xhci-ext-caps.h
@@ -73,6 +73,11 @@
 #define XHCI_HLC               (1 << 19)
 #define XHCI_BLC               (1 << 20)
 
+/* Debug capability - section 7.6.8 */
+#define XHCI_DBC_DCCTRL		0x20
+#define XHCI_DBC_DCCTRL_DCR	(1 << 0)
+#define XHCI_DBC_DCCTRL_DCE	(1 << 31)
+
 /* command register values to disable interrupts and halt the HC */
 /* start/stop HC execution - do not write unless HC is halted*/
 #define XHCI_CMD_RUN		(1 << 0)
diff --git a/drivers/usb/host/xhci-sysfs.c b/drivers/usb/host/xhci-sysfs.c
new file mode 100644
index 0000000..9feb727
--- /dev/null
+++ b/drivers/usb/host/xhci-sysfs.c
@@ -0,0 +1,65 @@
+/*
+ * sysfs interface for xHCI host controller driver
+ *
+ * Copyright (C) 2015 Intel Corp.
+ *
+ * Author: Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+#include <linux/kernel.h>
+
+#include "xhci.h"
+
+#define GET_DBC_EXT_CAP_OFFSET(h)	\
+		xhci_find_next_ext_cap(&(h)->cap_regs->hc_capbase, \
+		0, XHCI_EXT_CAPS_DEBUG)
+
+static ssize_t debug_port_state_show(struct device *dev,
+		struct device_attribute *attr, char *buf)
+{
+	int		count = 0, offset;
+	char		*state;
+	void __iomem	*dbc_base;
+	u32		dcctrl_reg;
+	struct xhci_hcd	*xhci = hcd_to_xhci(dev_get_drvdata(dev));
+
+	offset = GET_DBC_EXT_CAP_OFFSET(xhci);
+	if (!offset)
+		return 0;
+
+	dbc_base = (void __iomem *) xhci->cap_regs + offset;
+	dcctrl_reg = readl(dbc_base + XHCI_DBC_DCCTRL);
+
+	if (!(dcctrl_reg & XHCI_DBC_DCCTRL_DCE))
+		state = "disabled";
+	else if (dcctrl_reg & XHCI_DBC_DCCTRL_DCR)
+		state = "configured";
+	else
+		state = "enabled";
+
+	count = scnprintf(buf, PAGE_SIZE, "%s\n", state);
+
+	return count;
+}
+static DEVICE_ATTR_RO(debug_port_state);
+
+int xhci_sysfs_create_files(struct xhci_hcd *xhci)
+{
+	struct device *dev = xhci_to_hcd(xhci)->self.controller;
+
+	if (GET_DBC_EXT_CAP_OFFSET(xhci))
+		return device_create_file(dev, &dev_attr_debug_port_state);
+
+	return 0;
+}
+
+void xhci_sysfs_remove_files(struct xhci_hcd *xhci)
+{
+	struct device *dev = xhci_to_hcd(xhci)->self.controller;
+
+	if (GET_DBC_EXT_CAP_OFFSET(xhci))
+		device_remove_file(dev, &dev_attr_debug_port_state);
+}
diff --git a/drivers/usb/host/xhci.c b/drivers/usb/host/xhci.c
index 26a44c0..450f8f5 100644
--- a/drivers/usb/host/xhci.c
+++ b/drivers/usb/host/xhci.c
@@ -666,6 +666,9 @@ int xhci_run(struct usb_hcd *hcd)
 	}
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init,
 			"Finished xhci_run for USB2 roothub");
+
+	xhci_sysfs_create_files(xhci);
+
 	return 0;
 }
 EXPORT_SYMBOL_GPL(xhci_run);
@@ -699,6 +702,7 @@ void xhci_stop(struct usb_hcd *hcd)
 	xhci_reset(xhci);
 	spin_unlock_irq(&xhci->lock);
 
+	xhci_sysfs_remove_files(xhci);
 	xhci_cleanup_msix(xhci);
 
 	/* Deleting Compliance Mode Recovery Timer */
diff --git a/drivers/usb/host/xhci.h b/drivers/usb/host/xhci.h
index 9be7348..c2be2a0 100644
--- a/drivers/usb/host/xhci.h
+++ b/drivers/usb/host/xhci.h
@@ -1953,4 +1953,8 @@ struct xhci_input_control_ctx *xhci_get_input_control_ctx(struct xhci_container_
 struct xhci_slot_ctx *xhci_get_slot_ctx(struct xhci_hcd *xhci, struct xhci_container_ctx *ctx);
 struct xhci_ep_ctx *xhci_get_ep_ctx(struct xhci_hcd *xhci, struct xhci_container_ctx *ctx, unsigned int ep_index);
 
+/* xHCI sysfs interfaces */
+int xhci_sysfs_create_files(struct xhci_hcd *xhci);
+void xhci_sysfs_remove_files(struct xhci_hcd *xhci);
+
 #endif /* __LINUX_XHCI_HCD_H */
-- 
2.1.4