usb: typec: Add driver for DisplayPort alternate mode

DisplayPort USB Type-C Alt Mode allows DisplayPort displays
and adapters to be attached to the USB Type-C ports on the
system.

Signed-off-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Tested-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Documentation/ABI/testing/sysfs-driver-typec-displayport

@@ -0,0 +1,49 @@
+What:		/sys/bus/typec/devices/.../displayport/configuration
+Date:		July 2018
+Contact:	Heikki Krogerus <heikki.krogerus@linux.intel.com>
+Description:
+		Shows the current DisplayPort configuration for the connector.
+		Valid values are USB, source and sink. Source means DisplayPort
+		source, and sink means DisplayPort sink.
+
+		All supported configurations are listed as space separated list
+		with the active one wrapped in square brackets.
+
+		Source example:
+
+			USB [source] sink
+
+		The configuration can be changed by writing to the file
+
+		Note. USB configuration does not equal to Exit Mode. It is
+		separate configuration defined in VESA DisplayPort Alt Mode on
+		USB Type-C Standard. Functionally it equals to the situation
+		where the mode has been exited (to exit the mode, see
+		Documentation/ABI/testing/sysfs-bus-typec, and use file
+		/sys/bus/typec/devices/.../active).
+
+What:		/sys/bus/typec/devices/.../displayport/pin_assignment
+Date:		July 2018
+Contact:	Heikki Krogerus <heikki.krogerus@linux.intel.com>
+Description:
+		VESA DisplayPort Alt Mode on USB Type-C Standard defines six
+		different pin assignments for USB Type-C connector that are
+		labeled A, B, C, D, E, and F. The supported pin assignments are
+		listed as space separated list with the active one wrapped in
+		square brackets.
+
+		Example:
+
+			C [D]
+
+		Pin assignment can be changed by writing to the file. It is
+		possible to set pin assignment before configuration has been
+		set, but the assignment will not be active before the
+		connector is actually configured.
+
+		Note. As of VESA DisplayPort Alt Mode on USB Type-C Standard
+		version 1.0b, pin assignments A, B, and F are deprecated. Only
+		pin assignment D can now carry simultaneously one channel of
+		USB SuperSpeed protocol. From user perspective pin assignments C
+		and E are equal, where all channels on the connector are used
+		for carrying DisplayPort protocol (allowing higher resolutions).

drivers/usb/typec/Kconfig

@@ -104,4 +104,6 @@ config TYPEC_TPS6598X
 
 source "drivers/usb/typec/mux/Kconfig"
 
+source "drivers/usb/typec/altmodes/Kconfig"
+
 endif # TYPEC

drivers/usb/typec/Makefile

@@ -1,6 +1,7 @@
 # SPDX-License-Identifier: GPL-2.0
 obj-$(CONFIG_TYPEC)		+= typec.o
 typec-y				:= class.o mux.o bus.o
+obj-$(CONFIG_TYPEC)		+= altmodes/
 obj-$(CONFIG_TYPEC_TCPM)	+= tcpm.o
 obj-y				+= fusb302/
 obj-$(CONFIG_TYPEC_WCOVE)	+= typec_wcove.o

drivers/usb/typec/altmodes/Kconfig

@@ -0,0 +1,14 @@
+
+menu "USB Type-C Alternate Mode drivers"
+
+config TYPEC_DP_ALTMODE
+	tristate "DisplayPort Alternate Mode driver"
+	help
+	  DisplayPort USB Type-C Alternate Mode allows DisplayPort
+	  displays and adapters to be attached to the USB Type-C
+	  connectors on the system.
+
+	  To compile this driver as a module, choose M here: the
+	  module will be called typec_displayport.
+
+endmenu

drivers/usb/typec/altmodes/Makefile

@@ -0,0 +1,2 @@
+obj-$(CONFIG_TYPEC_DP_ALTMODE)		+= typec_displayport.o
+typec_displayport-y			:= displayport.o

include/linux/usb/typec_dp.h

@@ -0,0 +1,95 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __USB_TYPEC_DP_H
+#define __USB_TYPEC_DP_H
+
+#include <linux/usb/typec_altmode.h>
+
+#define USB_TYPEC_DP_SID	0xff01
+#define USB_TYPEC_DP_MODE	1
+
+/*
+ * Connector states matching the pin assignments in DisplayPort Alt Mode
+ * Specification.
+ *
+ * These values are meant primarily to be used by the mux drivers, but they are
+ * also used as the "value" part in the alternate mode notification chain, so
+ * receivers of those notifications will always see them.
+ *
+ * Note. DisplayPort USB Type-C Alt Mode Specification version 1.0b deprecated
+ * pin assignments A, B and F, but they are still defined here for legacy
+ * purposes.
+ */
+enum {
+	TYPEC_DP_STATE_A = TYPEC_STATE_MODAL,	/* Not supported after v1.0b */
+	TYPEC_DP_STATE_B,			/* Not supported after v1.0b */
+	TYPEC_DP_STATE_C,
+	TYPEC_DP_STATE_D,
+	TYPEC_DP_STATE_E,
+	TYPEC_DP_STATE_F,			/* Not supported after v1.0b */
+};
+
+/*
+ * struct typec_displayport_data - DisplayPort Alt Mode specific data
+ * @status: Status Update command VDO content
+ * @conf: Configure command VDO content
+ *
+ * This structure is delivered as the data part with the notifications. It
+ * contains the VDOs from the two DisplayPort Type-C alternate mode specific
+ * commands: Status Update and Configure.
+ *
+ * @status will show for example the status of the HPD signal.
+ */
+struct typec_displayport_data {
+	u32 status;
+	u32 conf;
+};
+
+enum {
+	DP_PIN_ASSIGN_A, /* Not supported after v1.0b */
+	DP_PIN_ASSIGN_B, /* Not supported after v1.0b */
+	DP_PIN_ASSIGN_C,
+	DP_PIN_ASSIGN_D,
+	DP_PIN_ASSIGN_E,
+	DP_PIN_ASSIGN_F, /* Not supported after v1.0b */
+};
+
+/* DisplayPort alt mode specific commands */
+#define DP_CMD_STATUS_UPDATE		VDO_CMD_VENDOR(0)
+#define DP_CMD_CONFIGURE		VDO_CMD_VENDOR(1)
+
+/* DisplayPort Capabilities VDO bits (returned with Discover Modes) */
+#define DP_CAP_CAPABILITY(_cap_)	((_cap_) & 3)
+#define   DP_CAP_UFP_D			1
+#define   DP_CAP_DFP_D			2
+#define   DP_CAP_DFP_D_AND_UFP_D	3
+#define DP_CAP_DP_SIGNALING		BIT(2) /* Always set */
+#define DP_CAP_GEN2			BIT(3) /* Reserved after v1.0b */
+#define DP_CAP_RECEPTACLE		BIT(6)
+#define DP_CAP_USB			BIT(7)
+#define DP_CAP_DFP_D_PIN_ASSIGN(_cap_)	(((_cap_) & GENMASK(15, 8)) >> 8)
+#define DP_CAP_UFP_D_PIN_ASSIGN(_cap_)	(((_cap_) & GENMASK(23, 16)) >> 16)
+
+/* DisplayPort Status Update VDO bits */
+#define DP_STATUS_CONNECTION(_status_)	((_status_) & 3)
+#define   DP_STATUS_CON_DISABLED	0
+#define   DP_STATUS_CON_DFP_D		1
+#define   DP_STATUS_CON_UFP_D		2
+#define   DP_STATUS_CON_BOTH		3
+#define DP_STATUS_POWER_LOW		BIT(2)
+#define DP_STATUS_ENABLED		BIT(3)
+#define DP_STATUS_PREFER_MULTI_FUNC	BIT(4)
+#define DP_STATUS_SWITCH_TO_USB		BIT(5)
+#define DP_STATUS_EXIT_DP_MODE		BIT(6)
+#define DP_STATUS_HPD_STATE		BIT(7) /* 0 = HPD_Low, 1 = HPD_High */
+#define DP_STATUS_IRQ_HPD		BIT(8)
+
+/* DisplayPort Configurations VDO bits */
+#define DP_CONF_CURRENTLY(_conf_)	((_conf_) & 3)
+#define DP_CONF_UFP_U_AS_DFP_D		BIT(0)
+#define DP_CONF_UFP_U_AS_UFP_D		BIT(1)
+#define DP_CONF_SIGNALING_DP		BIT(2)
+#define DP_CONF_SIGNALING_GEN_2		BIT(3) /* Reserved after v1.0b */
+#define DP_CONF_PIN_ASSIGNEMENT_SHIFT	8
+#define DP_CONF_PIN_ASSIGNEMENT_MASK	GENMASK(15, 8)
+
+#endif /* __USB_TYPEC_DP_H */