drivers/usb/core/of.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * of.c         The helpers for hcd device tree support
   4  *
   5  * Copyright (C) 2016 Freescale Semiconductor, Inc.
   6  *      Author: Peter Chen <peter.chen@freescale.com>
   7  * Copyright (C) 2017 Johan Hovold <johan@kernel.org>
   8  */
   9
  10 #include <linux/of.h>
  11 #include <linux/of_graph.h>
  12 #include <linux/usb/of.h>
  13
  14 /**
  15  * usb_of_get_device_node() - get a USB device node
  16  * @hub: hub to which device is connected
  17  * @port1: one-based index of port
  18  *
  19  * Look up the node of a USB device given its parent hub device and one-based
  20  * port number.
  21  *
  22  * Return: A pointer to the node with incremented refcount if found, or
  23  * %NULL otherwise.
  24  */
  25 struct device_node *usb_of_get_device_node(struct usb_device *hub, int port1)
  26 {
  27         struct device_node *node;
  28         u32 reg;
  29
  30         for_each_child_of_node(hub->dev.of_node, node) {
  31                 if (of_property_read_u32(node, "reg", &reg))
  32                         continue;
  33
  34                 if (reg == port1)
  35                         return node;
  36         }
  37
  38         return NULL;
  39 }
  40 EXPORT_SYMBOL_GPL(usb_of_get_device_node);
  41
  42 /**
  43  * usb_of_has_combined_node() - determine whether a device has a combined node
  44  * @udev: USB device
  45  *
  46  * Determine whether a USB device has a so called combined node which is
  47  * shared with its sole interface. This is the case if and only if the device
  48  * has a node and its descriptors report the following:
  49  *
  50  *      1) bDeviceClass is 0 or 9, and
  51  *      2) bNumConfigurations is 1, and
  52  *      3) bNumInterfaces is 1.
  53  *
  54  * Return: True iff the device has a device node and its descriptors match the
  55  * criteria for a combined node.
  56  */
  57 bool usb_of_has_combined_node(struct usb_device *udev)
  58 {
  59         struct usb_device_descriptor *ddesc = &udev->descriptor;
  60         struct usb_config_descriptor *cdesc;
  61
  62         if (!udev->dev.of_node)
  63                 return false;
  64
  65         switch (ddesc->bDeviceClass) {
  66         case USB_CLASS_PER_INTERFACE:
  67         case USB_CLASS_HUB:
  68                 if (ddesc->bNumConfigurations == 1) {
  69                         cdesc = &udev->config->desc;
  70                         if (cdesc->bNumInterfaces == 1)
  71                                 return true;
  72                 }
  73         }
  74
  75         return false;
  76 }
  77 EXPORT_SYMBOL_GPL(usb_of_has_combined_node);
  78
  79 static bool usb_of_has_devices_or_graph(const struct usb_device *hub)
  80 {
  81         const struct device_node *np = hub->dev.of_node;
  82         struct device_node *child;
  83
  84         if (of_graph_is_present(np))
  85                 return true;
  86
  87         for_each_child_of_node(np, child) {
  88                 if (of_property_present(child, "reg")) {
  89                         of_node_put(child);
  90                         return true;
  91                 }
  92         }
  93
  94         return false;
  95 }
  96
  97 /**
  98  * usb_of_get_connect_type() - get a USB hub's port connect_type
  99  * @hub: hub to which port is for @port1
 100  * @port1: one-based index of port
 101  *
 102  * Get the connect_type of @port1 based on the device node for @hub. If the
 103  * port is described in the OF graph, the connect_type is "hotplug". If the
 104  * @hub has a child device has with a 'reg' property equal to @port1 the
 105  * connect_type is "hard-wired". If there isn't an OF graph or child node at
 106  * all then the connect_type is "unknown". Otherwise, the port is considered
 107  * "unused" because it isn't described at all.
 108  *
 109  * Return: A connect_type for @port1 based on the device node for @hub.
 110  */
 111 enum usb_port_connect_type usb_of_get_connect_type(struct usb_device *hub, int port1)
 112 {
 113         struct device_node *np, *child, *ep, *remote_np;
 114         enum usb_port_connect_type connect_type;
 115
 116         /* Only set connect_type if binding has ports/hardwired devices. */
 117         if (!usb_of_has_devices_or_graph(hub))
 118                 return USB_PORT_CONNECT_TYPE_UNKNOWN;
 119
 120         /* Assume port is unused if there's a graph or a child node. */
 121         connect_type = USB_PORT_NOT_USED;
 122
 123         np = hub->dev.of_node;
 124         /*
 125          * Hotplug ports are connected to an available remote node, e.g.
 126          * usb-a-connector compatible node, in the OF graph.
 127          */
 128         if (of_graph_is_present(np)) {
 129                 ep = of_graph_get_endpoint_by_regs(np, port1, -1);
 130                 if (ep) {
 131                         remote_np = of_graph_get_remote_port_parent(ep);
 132                         of_node_put(ep);
 133                         if (of_device_is_available(remote_np))
 134                                 connect_type = USB_PORT_CONNECT_TYPE_HOT_PLUG;
 135                         of_node_put(remote_np);
 136                 }
 137         }
 138
 139         /*
 140          * Hard-wired ports are child nodes with a reg property corresponding
 141          * to the port number, i.e. a usb device.
 142          */
 143         child = usb_of_get_device_node(hub, port1);
 144         if (of_device_is_available(child))
 145                 connect_type = USB_PORT_CONNECT_TYPE_HARD_WIRED;
 146         of_node_put(child);
 147
 148         return connect_type;
 149 }
 150 EXPORT_SYMBOL_GPL(usb_of_get_connect_type);
 151
 152 /**
 153  * usb_of_get_interface_node() - get a USB interface node
 154  * @udev: USB device of interface
 155  * @config: configuration value
 156  * @ifnum: interface number
 157  *
 158  * Look up the node of a USB interface given its USB device, configuration
 159  * value and interface number.
 160  *
 161  * Return: A pointer to the node with incremented refcount if found, or
 162  * %NULL otherwise.
 163  */
 164 struct device_node *
 165 usb_of_get_interface_node(struct usb_device *udev, u8 config, u8 ifnum)
 166 {
 167         struct device_node *node;
 168         u32 reg[2];
 169
 170         for_each_child_of_node(udev->dev.of_node, node) {
 171                 if (of_property_read_u32_array(node, "reg", reg, 2))
 172                         continue;
 173
 174                 if (reg[0] == ifnum && reg[1] == config)
 175                         return node;
 176         }
 177
 178         return NULL;
 179 }
 180 EXPORT_SYMBOL_GPL(usb_of_get_interface_node);