[PATCH] USB: USB gadgets can autoconfigure endpoints

This adds some code that gadget drivers can call from
driver initialization, to simplify the "configure against
this hardware" step.


Add endpoint autoconfiguration for gadget drivers.

Endpoint selection is currently being done with conditional compilation.
That doesn't look nice, but more importantly it doesn't work well with
the model that some distributions won't be custom-matched to hardware.
Say, a PDA distro running on iPaq (pxa2xx_udc) or Axim (mq11xx_udc).

This code just makes it easier for drivers to match to hardware at
run-time.  It's a convenience function for something they could have
been doing already, but weren't.

drivers/usb/gadget/epautoconf.c

+/*
+ * epautoconf.c -- endpoint autoconfiguration for usb gadget drivers
+ *
+ * Copyright (C) 2004 David Brownell
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ *
+ */
+
+#include <linux/kernel.h>
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/device.h>
+
+#include <linux/ctype.h>
+#include <linux/string.h>
+
+#include <linux/usb_ch9.h>
+#include <linux/usb_gadget.h>
+
+#include "gadget_chips.h"
+
+
+/* we must assign addresses for configurable endpoints (like net2280) */
+static __initdata unsigned epnum;
+
+// #define MANY_ENDPOINTS
+#ifdef MANY_ENDPOINTS
+/* more than 15 configurable endpoints */
+static __initdata unsigned in_epnum;
+#endif
+
+
+/*
+ * This should work with endpoints from controller drivers sharing the
+ * same endpoint naming convention.  By example:
+ *
+ *	- ep1, ep2, ... address is fixed, not direction or type
+ *	- ep1in, ep2out, ... address and direction are fixed, not type
+ *	- ep1-bulk, ep2-bulk, ... address and type are fixed, not direction
+ *	- ep1in-bulk, ep2out-iso, ... all three are fixed
+ *	- ep-* ... no functionality restrictions
+ *
+ * Type suffixes are "-bulk", "-iso", or "-int".  Numbers are decimal.
+ * Less common restrictions are implied by gadget_is_*().
+ */
+static int __init
+ep_matches (
+	struct usb_gadget		*gadget,
+	struct usb_ep			*ep,
+	struct usb_endpoint_descriptor	*desc
+)
+{
+	u8		type;
+	const char	*tmp;
+	u16		max;
+
+	/* endpoint already claimed? */
+	if (0 != ep->driver_data)
+		return 0;
+		
+	/* only support ep0 for portable CONTROL traffic */
+	type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
+	if (USB_ENDPOINT_XFER_CONTROL == type)
+		return 0;
+
+	/* some other naming convention */
+	if ('e' != ep->name[0])
+		return 0;
+
+	/* type-restriction:  "-iso", "-bulk", or "-int".
+	 * direction-restriction:  "in", "out".
+	 */
+	if ('-' != ep->name[2]) {
+		tmp = strrchr (ep->name, '-');
+		if (tmp) {
+			switch (type) {
+			case USB_ENDPOINT_XFER_INT:
+				/* bulk endpoints handle interrupt transfers,
+				 * except the toggle-quirky iso-synch kind
+				 */
+				if ('s' != tmp[2])	// == "-iso"
+					return 0;
+				/* for now, avoid PXA "interrupt-in";
+				 * it's documented as never using DATA1.
+				 */
+				if (gadget_is_pxa (gadget))
+					return 0;
+				break;
+			case USB_ENDPOINT_XFER_BULK:
+				if ('b' != tmp[1])	// != "-bulk"
+					return 0;
+				break;
+			case USB_ENDPOINT_XFER_ISOC:
+				if ('s' != tmp[2])	// != "-iso"
+					return 0;
+			}
+		} else {
+			tmp = ep->name + strlen (ep->name);
+		}
+
+		/* direction-restriction:  "..in-..", "out-.." */
+		tmp--;
+		if (!isdigit (*tmp)) {
+			if (desc->bEndpointAddress & USB_DIR_IN) {
+				if ('n' != *tmp)
+					return 0;
+			} else {
+				if ('t' != *tmp)
+					return 0;
+			}
+		}
+	}
+
+	/* endpoint maxpacket size is an input parameter, except for bulk
+	 * where it's an output parameter representing the full speed limit.
+	 * the usb spec fixes high speed bulk maxpacket at 512 bytes.
+	 */
+	max = 0x7ff & le16_to_cpup (&desc->wMaxPacketSize);
+	switch (type) {
+	case USB_ENDPOINT_XFER_INT:
+		/* INT:  limit 64 bytes full speed, 1024 high speed */
+		if (!gadget->is_dualspeed && max > 64)
+			return 0;
+		/* FALLTHROUGH */
+
+	case USB_ENDPOINT_XFER_ISOC:
+		/* ISO:  limit 1023 bytes full speed, 1024 high speed */
+		if (ep->maxpacket < max)
+			return 0;
+		if (!gadget->is_dualspeed && max > 1023)
+			return 0;
+
+		/* BOTH:  "high bandwidth" works only at high speed */
+		if ((desc->wMaxPacketSize & __constant_cpu_to_le16(3<<11))) {
+			if (!gadget->is_dualspeed)
+				return 0;
+			/* configure your hardware with enough buffering!! */
+		}
+		break;
+	}
+
+	/* MATCH!! */
+
+	/* report address */
+	if (isdigit (ep->name [2])) {
+		u8	num = simple_strtol (&ep->name [2], NULL, 10);
+		desc->bEndpointAddress |= num;
+#ifdef	MANY_ENDPOINTS
+	} else if (desc->bEndpointAddress & USB_DIR_IN) {
+		if (++in_epnum > 15)
+			return 0;
+		desc->bEndpointAddress = USB_DIR_IN | in_epnum;
+#endif
+	} else {
+		if (++epnum > 15)
+			return 0;
+		desc->bEndpointAddress |= epnum;
+	}
+
+	/* report (variable) full speed bulk maxpacket */
+	if (USB_ENDPOINT_XFER_BULK == type)
+		desc->wMaxPacketSize = cpu_to_le16 (
+				min ((unsigned)64, ep->maxpacket));
+	return 1;
+}
+
+static struct usb_ep * __init
+find_ep (struct usb_gadget *gadget, const char *name)
+{
+	struct usb_ep	*ep;
+
+	list_for_each_entry (ep, &gadget->ep_list, ep_list) {
+		if (0 == strcmp (ep->name, name))
+			return ep;
+	}
+	return 0;
+}
+
+/**
+ * usb_ep_autoconfig - choose an endpoint matching the descriptor
+ * @gadget: The device to which the endpoint must belong.
+ * @desc: Endpoint descriptor, with endpoint direction and transfer mode
+ *	initialized.  For periodic transfers, the maximum packet
+ *	size must also be initialized.  This is modified on success.
+ *
+ * By choosing an endpoint to use with the specified descriptor, this
+ * routine simplifies writing gadget drivers that work with multiple
+ * USB device controllers.  The endpoint would be passed later to
+ * usb_ep_enable(), along with some descriptor.
+ *
+ * That second descriptor won't always be the same as the first one.
+ * For example, isochronous endpoints can be autoconfigured for high
+ * bandwidth, and then used in several lower bandwidth altsettings.
+ * Also, high and full speed descriptors will be different.
+ *
+ * Be sure to examine and test the results of autoconfiguration on your
+ * hardware.  This code may not make the best choices about how to use the
+ * USB controller, and it can't know all the restrictions that may apply.
+ * Some combinations of driver and hardware won't be able to autoconfigure.
+ *
+ * On success, this returns an un-claimed usb_ep, and modifies the endpoint
+ * descriptor bEndpointAddress.  For bulk endpoints, the wMaxPacket value
+ * is initialized as if the endpoint were used at full speed.  To prevent
+ * the endpoint from being returned by a later autoconfig call, claim it
+ * by assigning ep->driver_data to some non-null value.
+ *
+ * On failure, this returns a null endpoint descriptor.
+ */
+struct usb_ep * __init usb_ep_autoconfig (
+	struct usb_gadget		*gadget,
+	struct usb_endpoint_descriptor	*desc
+)
+{
+	struct usb_ep	*ep;
+	u8		type;
+
+	type = desc->bmAttributes & USB_ENDPOINT_XFERTYPE_MASK;
+
+	/* First, apply chip-specific "best usage" knowledge.
+	 * This might make a good usb_gadget_ops hook ...
+	 */
+	if (gadget_is_net2280 (gadget) && type == USB_ENDPOINT_XFER_INT) {
+		/* ep-e, ep-f are PIO with only 64 byte fifos */
+		ep = find_ep (gadget, "ep-e");
+		if (ep && ep_matches (gadget, ep, desc))
+			return ep;
+		ep = find_ep (gadget, "ep-f");
+		if (ep && ep_matches (gadget, ep, desc))
+			return ep;
+
+	} else if (gadget_is_goku (gadget)) {
+		if (USB_ENDPOINT_XFER_INT == type) {
+			/* single buffering is enough */
+			ep = find_ep (gadget, "ep3-bulk");
+			if (ep && ep_matches (gadget, ep, desc))
+				return ep;
+		} else if (USB_ENDPOINT_XFER_BULK == type
+				&& (USB_DIR_IN & desc->bEndpointAddress)) {
+			/* DMA may be available */
+			ep = find_ep (gadget, "ep2-bulk");
+			if (ep && ep_matches (gadget, ep, desc))
+				return ep;
+		}
+
+	} else if (gadget_is_sh (gadget) && USB_ENDPOINT_XFER_INT == type) {
+		/* single buffering is enough; maybe 8 byte fifo is too */
+		ep = find_ep (gadget, "ep3in-bulk");
+		if (ep && ep_matches (gadget, ep, desc))
+			return ep;
+
+	} else if (gadget_is_mq11xx (gadget) && USB_ENDPOINT_XFER_INT == type) {
+		ep = find_ep (gadget, "ep1-bulk");
+		if (ep && ep_matches (gadget, ep, desc))
+			return ep;
+	}
+
+	/* Second, look at endpoints until an unclaimed one looks usable */ 
+	list_for_each_entry (ep, &gadget->ep_list, ep_list) {
+		if (ep_matches (gadget, ep, desc))
+			return ep;
+	}
+
+	/* Fail */
+	return 0;
+}
+
+/**
+ * usb_ep_autoconfig_reset - reset endpoint autoconfig state
+ * @gadget: device for which autoconfig state will be reset
+ *
+ * Use this for devices where one configuration may need to assign
+ * endpoint resources very differently from the next one.  It clears
+ * state such as ep->driver_data and the record of assigned endpoints
+ * used by usb_ep_autoconfig().
+ */
+void __init usb_ep_autoconfig_reset (struct usb_gadget *gadget)
+{
+	struct usb_ep	*ep;
+
+	list_for_each_entry (ep, &gadget->ep_list, ep_list) {
+		ep->driver_data = 0;
+	}
+#ifdef	MANY_ENDPOINTS
+	in_epnum = 0;
+#endif
+	epnum = 0;
+}
+

drivers/usb/gadget/usbstring.c

@@ -12,6 +12,7 @@
 #include <linux/list.h>
 #include <linux/string.h>
 #include <linux/device.h>
+#include <linux/init.h>
 
 #include <linux/usb_ch9.h>
 #include <linux/usb_gadget.h>

include/linux/usb_gadget.h

@@ -731,6 +731,15 @@ int usb_descriptor_fillbuf(void *, unsigned,
 int usb_gadget_config_buf(const struct usb_config_descriptor *config,
 	void *buf, unsigned buflen, const struct usb_descriptor_header **desc);
 
+/*-------------------------------------------------------------------------*/
+
+/* utility wrapping a simple endpoint selection policy */
+
+extern struct usb_ep *usb_ep_autoconfig (struct usb_gadget *,
+			struct usb_endpoint_descriptor *) __init;
+
+extern void usb_ep_autoconfig_reset (struct usb_gadget *) __init;
+
 #endif  /* __KERNEL__ */
 
 #endif	/* __LINUX_USB_GADGET_H */