Quoting Stephen Boyd (2016-09-13 18:42:46) > On the db410c 96boards platform we have a TC7USB40MU[1] on the > board to mux the D+/D- lines from the SoC between a micro usb > "device" port and a USB hub for "host" roles. Upon a role switch, > we need to change this mux to forward the D+/D- lines to either > the port or the hub. Therefore, introduce a driver for this > device that intercepts extcon USB_HOST events and logically > asserts a gpio to mux the "host" D+/D- lines when a host cable is > attached. When the cable goes away, it will logically deassert > the gpio and mux the "device" lines. > > [1] https://toshiba.semicon-storage.com/ap-en/product/logic/bus-switch/detail.TC7USB40MU.html > > Cc: MyungJoo Ham <myungjoo.ham@xxxxxxxxxxx> > Cc: Chanwoo Choi <cw00.choi@xxxxxxxxxxx> > Cc: <devicetree@xxxxxxxxxxxxxxx> > Signed-off-by: Stephen Boyd <stephen.boyd@xxxxxxxxxx> > --- > > Should I make the extcon part optional? I could see a case where there are two > "OTG" ports connected to the mux (or two hubs), and for some reason the > software may want to mux between them at runtime. If we mandate an extcon, > that won't be possible to support. Perhaps it would be better to have > the node, but connect it to the usb controller with a phandle (maybe of_graph > endpoints would be useful too) so that when the controller wants to mux over > a port it can do so. Here's some dts mock-up on top of the db410c for the of_graph stuff. I haven't written any code around it, but the idea is to allow the binding to specify how the mux is connected to upstream and downstream D+/D- lines. This way, we can do some dt parsing of the endpoints and their parent nodes to figure out if the mux needs to be set high or low to use a device connector or a usb hub based on if the id cable is present. Maybe I'm over thinking things though and we could just have a DT property for that. soc { usb@78d9000 { extcon = <&usb_id>, <&usb_id>; usb-controller; // needed? ports { #address-cells = <1>; #size-cells = <0>; port@0 { #address-cells = <1>; #size-cells = <0>; reg = <0>; usb_output: endpoint@0 { // USB D+/D- reg = <0>; remote-endpoint = <&usb_switch_input>; }; }; }; }; }; usb2513 { compatible = "smsc,usb3503"; reset-gpios = <&pm8916_gpios 3 GPIO_ACTIVE_LOW>; initial-mode = <1>; usb-hub; // indicate this is a hub ports { #address-cells = <1>; #size-cells = <0>; port@0 { #address-cells = <1>; #size-cells = <0>; reg = <0>; usb_hub_input: endpoint@0 { // USB{DP,DM}_UP reg = <0>; remote-endpoint = <&usb_switch_hub_ep>; }; usb_hub_output1: endpoint@1 { // USB{DP,DM}_DN1 reg = <1>; remote-endpoint = <&usb_a2_connector>; }; usb_hub_output2: endpoint@2 { // USB{DP,DM}_DN2 reg = <2>; remote-endpoint = <&usb_a1_connector>; }; usb_hub_output3: endpoint@3 { // USB{DP,DM}_DN3 reg = <3>; // goes to expansion connector }; }; }; }; usb_id: usb-id { compatible = "linux,extcon-usb-gpio"; id-gpio = <&msmgpio 121 GPIO_ACTIVE_HIGH>; pinctrl-names = "default"; pinctrl-0 = <&usb_id_default>; }; usb-switch { compatible = "toshiba,tc7usb40mu"; switch-gpios = <&pm8916_gpios 4 GPIO_ACTIVE_HIGH>; extcon = <&usb_id>; pinctrl-names = "default"; pinctrl-0 = <&usb_sw_sel_pm>; ports { #address-cells = <1>; #size-cells = <0>; port@0 { #address-cells = <1>; #size-cells = <0>; reg = <0>; usb_switch_input: endpoint@0 { // D+/D- reg = <0>; remote-endpoint = <&usb_output>; }; usb_switch_device_ep: endpoint@1 { // D1+/D1- reg = <1>; remote-endpoint = <&usb_ub_connector>; }; usb_switch_hub_ep: endpoint@2 { // D2+/D2- reg = <2>; remote-endpoint = <&usb_hub_input>; }; }; }; }; uB-connector { compatible = "usb-ub-connector"; #address-cells = <1>; #size-cells = <0>; usb-connector; port@0 { #address-cells = <1>; #size-cells = <0>; reg = <0>; usb_ub_connector: endpoint@0 { reg = <0>; remote-endpoint = <&usb_switch_device_ep>; }; }; }; usb-A-connector1 { compatible = "usb-A-connector"; #address-cells = <1>; #size-cells = <0>; usb-connector; port@0 { #address-cells = <1>; #size-cells = <0>; reg = <0>; usb_a1_connector: endpoint@0 { reg = <0>; remote-endpoint = <&usb_hub_output2>; }; }; }; usb-A-connector2 { compatible = "usb-A-connector"; #address-cells = <1>; #size-cells = <0>; usb-connector; port@0 { #address-cells = <1>; #size-cells = <0>; reg = <0>; usb_a2_connector: endpoint@0 { reg = <0>; remote-endpoint = <&usb_hub_output1>; }; }; }; }; -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
