usb: gadget: OS Feature Descriptors support

There is a custom (non-USB IF) extension to the USB standard:

http://msdn.microsoft.com/library/windows/hardware/gg463182

They grant permission to use the specification - there is
"Microsoft OS Descriptor Specification License Agreement"
under the link mentioned above, and its Section 2 "Grant
of License", letter (b) reads:

"Patent license. Microsoft hereby grants to You a nonexclusive,
royalty-free, nontransferable, worldwide license under Microsoft’s
patents embodied solely within the Specification and that are owned
or licensable by Microsoft to make, use, import, offer to sell,
sell and distribute directly or indirectly to Your Licensees Your
Implementation. You may sublicense this patent license to Your
Licensees under the same terms and conditions."

The said extension is maintained by Microsoft for Microsoft.

Yet it is fairly common for various devices to use it, and a
popular proprietary operating system expects devices to provide
"OS descriptors", so Linux-based USB gadgets whishing to be able
to talk to a variety of operating systems should be able to provide
the "OS descriptors".

This patch adds optional support for gadgets whishing to expose
the so called "OS Feature Descriptors", that is "Extended Compatibility ID"
and "Extended Properties".

Hosts which do request "OS descriptors" from gadgets do so during
the enumeration phase and before the configuration is set with
SET_CONFIGURATION. What is more, those hosts never ask for configurations
at indices other than 0. Therefore, gadgets whishing to provide
"OS descriptors" must designate one configuration to be used with
this kind of hosts - this is what os_desc_config is added for in
struct usb_composite_dev. There is an additional advantage to it:
if a gadget provides "OS descriptors" and designates one configuration
to be used with such non-USB-compliant hosts it can invoke
"usb_add_config" in any order because the designated configuration
will be reported to be at index 0 anyway.

This patch also adds handling vendor-specific requests addressed
at device or interface and related to handling "OS descriptors".

Signed-off-by: Andrzej Pietrasiewicz <[email protected]>
Acked-by: Michal Nazarewicz <[email protected]>
Signed-off-by: Felipe Balbi <[email protected]>

Author: Andrzej Pietrasiewicz

drivers/usb/gadget/composite.c

@@ -21,6 +21,8 @@
 #include <linux/usb/composite.h>
 #include <asm/unaligned.h>
 
+#include "u_os_desc.h"
+
 /**
  * struct usb_os_string - represents OS String to be reported by a gadget
  * @bLength: total length of the entire descritor, always 0x12
@@ -438,6 +440,7 @@ static int config_desc(struct usb_composite_dev *cdev, unsigned w_value)
 {
 	struct usb_gadget		*gadget = cdev->gadget;
 	struct usb_configuration	*c;
+	struct list_head		*pos;
 	u8				type = w_value >> 8;
 	enum usb_device_speed		speed = USB_SPEED_UNKNOWN;
 
@@ -456,7 +459,20 @@ static int config_desc(struct usb_composite_dev *cdev, unsigned w_value)
 
 	/* This is a lookup by config *INDEX* */
 	w_value &= 0xff;
-	list_for_each_entry(c, &cdev->configs, list) {
+
+	pos = &cdev->configs;
+	c = cdev->os_desc_config;
+	if (c)
+		goto check_config;
+
+	while ((pos = pos->next) !=  &cdev->configs) {
+		c = list_entry(pos, typeof(*c), list);
+
+		/* skip OS Descriptors config which is handled separately */
+		if (c == cdev->os_desc_config)
+			continue;
+
+check_config:
 		/* ignore configs that won't work at this speed */
 		switch (speed) {
 		case USB_SPEED_SUPER:
@@ -1236,6 +1252,158 @@ static void composite_setup_complete(struct usb_ep *ep, struct usb_request *req)
 				req->status, req->actual, req->length);
 }
 
+static int count_ext_compat(struct usb_configuration *c)
+{
+	int i, res;
+
+	res = 0;
+	for (i = 0; i < c->next_interface_id; ++i) {
+		struct usb_function *f;
+		int j;
+
+		f = c->interface[i];
+		for (j = 0; j < f->os_desc_n; ++j) {
+			struct usb_os_desc *d;
+
+			if (i != f->os_desc_table[j].if_id)
+				continue;
+			d = f->os_desc_table[j].os_desc;
+			if (d && d->ext_compat_id)
+				++res;
+		}
+	}
+	BUG_ON(res > 255);
+	return res;
+}
+
+static void fill_ext_compat(struct usb_configuration *c, u8 *buf)
+{
+	int i, count;
+
+	count = 16;
+	for (i = 0; i < c->next_interface_id; ++i) {
+		struct usb_function *f;
+		int j;
+
+		f = c->interface[i];
+		for (j = 0; j < f->os_desc_n; ++j) {
+			struct usb_os_desc *d;
+
+			if (i != f->os_desc_table[j].if_id)
+				continue;
+			d = f->os_desc_table[j].os_desc;
+			if (d && d->ext_compat_id) {
+				*buf++ = i;
+				*buf++ = 0x01;
+				memcpy(buf, d->ext_compat_id, 16);
+				buf += 22;
+			} else {
+				++buf;
+				*buf = 0x01;
+				buf += 23;
+			}
+			count += 24;
+			if (count >= 4096)
+				return;
+		}
+	}
+}
+
+static int count_ext_prop(struct usb_configuration *c, int interface)
+{
+	struct usb_function *f;
+	int j, res;
+
+	res = 0;
+
+	f = c->interface[interface];
+	for (j = 0; j < f->os_desc_n; ++j) {
+		struct usb_os_desc *d;
+
+		if (interface != f->os_desc_table[j].if_id)
+			continue;
+		d = f->os_desc_table[j].os_desc;
+		if (d && d->ext_compat_id)
+			return d->ext_prop_count;
+	}
+	return res;
+}
+
+static int len_ext_prop(struct usb_configuration *c, int interface)
+{
+	struct usb_function *f;
+	struct usb_os_desc *d;
+	int j, res;
+
+	res = 10; /* header length */
+	f = c->interface[interface];
+	for (j = 0; j < f->os_desc_n; ++j) {
+		if (interface != f->os_desc_table[j].if_id)
+			continue;
+		d = f->os_desc_table[j].os_desc;
+		if (d)
+			return min(res + d->ext_prop_len, 4096);
+	}
+	return res;
+}
+
+static int fill_ext_prop(struct usb_configuration *c, int interface, u8 *buf)
+{
+	struct usb_function *f;
+	struct usb_os_desc *d;
+	struct usb_os_desc_ext_prop *ext_prop;
+	int j, count, n, ret;
+	u8 *start = buf;
+
+	f = c->interface[interface];
+	for (j = 0; j < f->os_desc_n; ++j) {
+		if (interface != f->os_desc_table[j].if_id)
+			continue;
+		d = f->os_desc_table[j].os_desc;
+		if (d)
+			list_for_each_entry(ext_prop, &d->ext_prop, entry) {
+				/* 4kB minus header length */
+				n = buf - start;
+				if (n >= 4086)
+					return 0;
+
+				count = ext_prop->data_len +
+					ext_prop->name_len + 14;
+				if (count > 4086 - n)
+					return -EINVAL;
+				usb_ext_prop_put_size(buf, count);
+				usb_ext_prop_put_type(buf, ext_prop->type);
+				ret = usb_ext_prop_put_name(buf, ext_prop->name,
+							    ext_prop->name_len);
+				if (ret < 0)
+					return ret;
+				switch (ext_prop->type) {
+				case USB_EXT_PROP_UNICODE:
+				case USB_EXT_PROP_UNICODE_ENV:
+				case USB_EXT_PROP_UNICODE_LINK:
+					usb_ext_prop_put_unicode(buf, ret,
+							 ext_prop->data,
+							 ext_prop->data_len);
+					break;
+				case USB_EXT_PROP_BINARY:
+					usb_ext_prop_put_binary(buf, ret,
+							ext_prop->data,
+							ext_prop->data_len);
+					break;
+				case USB_EXT_PROP_LE32:
+					/* not implemented */
+				case USB_EXT_PROP_BE32:
+					/* not implemented */
+				default:
+					return -EINVAL;
+				}
+				buf += count;
+			}
+	}
+
+	return 0;
+}
+
 /*
  * The setup() callback implements all the ep0 functionality that's
  * not handled lower down, in hardware or the hardware driver(like
@@ -1445,6 +1613,91 @@ composite_setup(struct usb_gadget *gadget, const struct usb_ctrlrequest *ctrl)
 		break;
 	default:
 unknown:
+		/*
+		 * OS descriptors handling
+		 */
+		if (cdev->use_os_string && cdev->os_desc_config &&
+		    (ctrl->bRequest & USB_TYPE_VENDOR) &&
+		    ctrl->bRequest == cdev->b_vendor_code) {
+			struct usb_request		*req;
+			struct usb_configuration	*os_desc_cfg;
+			u8				*buf;
+			int				interface;
+			int				count = 0;
+
+			req = cdev->os_desc_req;
+			req->complete = composite_setup_complete;
+			buf = req->buf;
+			os_desc_cfg = cdev->os_desc_config;
+			memset(buf, 0, w_length);
+			buf[5] = 0x01;
+			switch (ctrl->bRequestType & USB_RECIP_MASK) {
+			case USB_RECIP_DEVICE:
+				if (w_index != 0x4 || (w_value >> 8))
+					break;
+				buf[6] = w_index;
+				if (w_length == 0x10) {
+					/* Number of ext compat interfaces */
+					count = count_ext_compat(os_desc_cfg);
+					buf[8] = count;
+					count *= 24; /* 24 B/ext compat desc */
+					count += 16; /* header */
+					put_unaligned_le32(count, buf);
+					value = w_length;
+				} else {
+					/* "extended compatibility ID"s */
+					count = count_ext_compat(os_desc_cfg);
+					buf[8] = count;
+					count *= 24; /* 24 B/ext compat desc */
+					count += 16; /* header */
+					put_unaligned_le32(count, buf);
+					buf += 16;
+					fill_ext_compat(os_desc_cfg, buf);
+					value = w_length;
+				}
+				break;
+			case USB_RECIP_INTERFACE:
+				if (w_index != 0x5 || (w_value >> 8))
+					break;
+				interface = w_value & 0xFF;
+				buf[6] = w_index;
+				if (w_length == 0x0A) {
+					count = count_ext_prop(os_desc_cfg,
+						interface);
+					put_unaligned_le16(count, buf + 8);
+					count = len_ext_prop(os_desc_cfg,
+						interface);
+					put_unaligned_le32(count, buf);
+
+					value = w_length;
+				} else {
+					count = count_ext_prop(os_desc_cfg,
+						interface);
+					put_unaligned_le16(count, buf + 8);
+					count = len_ext_prop(os_desc_cfg,
+						interface);
+					put_unaligned_le32(count, buf);
+					buf += 10;
+					value = fill_ext_prop(os_desc_cfg,
+							      interface, buf);
+					if (value < 0)
+						return value;
+
+					value = w_length;
+				}
+				break;
+			}
+			req->length = value;
+			req->zero = value < w_length;
+			value = usb_ep_queue(gadget->ep0, req, GFP_ATOMIC);
+			if (value < 0) {
+				DBG(cdev, "ep_queue --> %d\n", value);
+				req->status = 0;
+				composite_setup_complete(gadget->ep0, req);
+			}
+			return value;
+		}
+
 		VDBG(cdev,
 			"non-core control req%02x.%02x v%04x i%04x l%d\n",
 			ctrl->bRequestType, ctrl->bRequest,
@@ -1668,6 +1921,29 @@ int composite_dev_prepare(struct usb_composite_driver *composite,
 	return ret;
 }
 
+int composite_os_desc_req_prepare(struct usb_composite_dev *cdev,
+				  struct usb_ep *ep0)
+{
+	int ret = 0;
+
+	cdev->os_desc_req = usb_ep_alloc_request(ep0, GFP_KERNEL);
+	if (!cdev->os_desc_req) {
+		ret = PTR_ERR(cdev->os_desc_req);
+		goto end;
+	}
+
+	/* OS feature descriptor length <= 4kB */
+	cdev->os_desc_req->buf = kmalloc(4096, GFP_KERNEL);
+	if (!cdev->os_desc_req->buf) {
+		ret = PTR_ERR(cdev->os_desc_req->buf);
+		kfree(cdev->os_desc_req);
+		goto end;
+	}
+	cdev->os_desc_req->complete = composite_setup_complete;
+end:
+	return ret;
+}
+
 void composite_dev_cleanup(struct usb_composite_dev *cdev)
 {
 	struct usb_gadget_string_container *uc, *tmp;
@@ -1676,6 +1952,10 @@ void composite_dev_cleanup(struct usb_composite_dev *cdev)
 		list_del(&uc->list);
 		kfree(uc);
 	}
+	if (cdev->os_desc_req) {
+		kfree(cdev->os_desc_req->buf);
+		usb_ep_free_request(cdev->gadget->ep0, cdev->os_desc_req);
+	}
 	if (cdev->req) {
 		kfree(cdev->req->buf);
 		usb_ep_free_request(cdev->gadget->ep0, cdev->req);
@@ -1713,6 +1993,12 @@ static int composite_bind(struct usb_gadget *gadget,
 	if (status < 0)
 		goto fail;
 
+	if (cdev->use_os_string) {
+		status = composite_os_desc_req_prepare(cdev, gadget->ep0);
+		if (status)
+			goto fail;
+	}
+
 	update_unchanged_dev_desc(&cdev->desc, composite->dev);
 
 	/* has userspace failed to provide a serial number? */