USB: gadget: add HID gadget driver

g_hid is a USB gadget driver implementing the Human Interface Device class
specification. The driver handles basic HID protocol handling in the
kernel, and allows userspace to read/write HID reports trough /dev/hidgX
character devices.
Signed-off-by: Fabien Chouteau <fabien.chouteau@barco.com>
Signed-off-by: Peter Korsgaard <peter.korsgaard@barco.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/usb/gadget/Kconfig

@@ -863,6 +863,17 @@ config USB_G_MULTI_CDC
 
 	  If unsure, say "y".
 
+config USB_G_HID
+	tristate "HID Gadget"
+	help
+	  The HID gadget driver provides generic emulation of USB
+	  Human Interface Devices (HID).
+
+	  For more information, see Documentation/usb/gadget_hid.txt which
+	  includes sample code for accessing the device files.
+
+	  Say "y" to link the driver statically, or "m" to build a
+	  dynamically linked module called "g_hid".
 
 # put drivers that need isochronous transfer support (for audio
 # or video class gadget drivers), or specific hardware, here.

drivers/usb/gadget/Makefile

@@ -43,6 +43,7 @@ g_mass_storage-objs		:= mass_storage.o
 g_printer-objs			:= printer.o
 g_cdc-objs			:= cdc2.o
 g_multi-objs			:= multi.o
+g_hid-objs			:= hid.o
 g_nokia-objs			:= nokia.o
 
 obj-$(CONFIG_USB_ZERO)		+= g_zero.o
@@ -55,6 +56,7 @@ obj-$(CONFIG_USB_G_SERIAL)	+= g_serial.o
 obj-$(CONFIG_USB_G_PRINTER)	+= g_printer.o
 obj-$(CONFIG_USB_MIDI_GADGET)	+= g_midi.o
 obj-$(CONFIG_USB_CDC_COMPOSITE) += g_cdc.o
+obj-$(CONFIG_USB_G_HID)		+= g_hid.o
 obj-$(CONFIG_USB_G_MULTI)	+= g_multi.o
 obj-$(CONFIG_USB_G_NOKIA)	+= g_nokia.o
 

drivers/usb/gadget/hid.c

+/*
+ * hid.c -- HID Composite driver
+ *
+ * Based on multi.c
+ *
+ * Copyright (C) 2010 Fabien Chouteau <fabien.chouteau@barco.com>
+ *
+ * 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/platform_device.h>
+#include <linux/list.h>
+
+#define DRIVER_DESC		"HID Gadget"
+#define DRIVER_VERSION		"2010/03/16"
+
+/*-------------------------------------------------------------------------*/
+
+#define HIDG_VENDOR_NUM		0x0525	/* XXX NetChip */
+#define HIDG_PRODUCT_NUM	0xa4ac	/* Linux-USB HID gadget */
+
+/*-------------------------------------------------------------------------*/
+
+/*
+ * kbuild is not very cooperative with respect to linking separately
+ * compiled library objects into one module.  So for now we won't use
+ * separate compilation ... ensuring init/exit sections work to shrink
+ * the runtime footprint, and giving us at least some parts of what
+ * a "gcc --combine ... part1.c part2.c part3.c ... " build would.
+ */
+
+#include "composite.c"
+#include "usbstring.c"
+#include "config.c"
+#include "epautoconf.c"
+
+#include "f_hid.c"
+
+
+struct hidg_func_node {
+	struct list_head node;
+	struct hidg_func_descriptor *func;
+};
+
+static LIST_HEAD(hidg_func_list);
+
+/*-------------------------------------------------------------------------*/
+
+static struct usb_device_descriptor device_desc = {
+	.bLength =		sizeof device_desc,
+	.bDescriptorType =	USB_DT_DEVICE,
+
+	.bcdUSB =		cpu_to_le16(0x0200),
+
+	/* .bDeviceClass =		USB_CLASS_COMM, */
+	/* .bDeviceSubClass =	0, */
+	/* .bDeviceProtocol =	0, */
+	.bDeviceClass =		0xEF,
+	.bDeviceSubClass =	2,
+	.bDeviceProtocol =	1,
+	/* .bMaxPacketSize0 = f(hardware) */
+
+	/* Vendor and product id can be overridden by module parameters.  */
+	.idVendor =		cpu_to_le16(HIDG_VENDOR_NUM),
+	.idProduct =		cpu_to_le16(HIDG_PRODUCT_NUM),
+	/* .bcdDevice = f(hardware) */
+	/* .iManufacturer = DYNAMIC */
+	/* .iProduct = DYNAMIC */
+	/* NO SERIAL NUMBER */
+	.bNumConfigurations =	1,
+};
+
+static struct usb_otg_descriptor otg_descriptor = {
+	.bLength =		sizeof otg_descriptor,
+	.bDescriptorType =	USB_DT_OTG,
+
+	/* REVISIT SRP-only hardware is possible, although
+	 * it would not be called "OTG" ...
+	 */
+	.bmAttributes =		USB_OTG_SRP | USB_OTG_HNP,
+};
+
+static const struct usb_descriptor_header *otg_desc[] = {
+	(struct usb_descriptor_header *) &otg_descriptor,
+	NULL,
+};
+
+
+/* string IDs are assigned dynamically */
+
+#define STRING_MANUFACTURER_IDX		0
+#define STRING_PRODUCT_IDX		1
+
+static char manufacturer[50];
+
+static struct usb_string strings_dev[] = {
+	[STRING_MANUFACTURER_IDX].s = manufacturer,
+	[STRING_PRODUCT_IDX].s = DRIVER_DESC,
+	{  } /* end of list */
+};
+
+static struct usb_gadget_strings stringtab_dev = {
+	.language	= 0x0409,	/* en-us */
+	.strings	= strings_dev,
+};
+
+static struct usb_gadget_strings *dev_strings[] = {
+	&stringtab_dev,
+	NULL,
+};
+
+
+
+/****************************** Configurations ******************************/
+
+static int __init do_config(struct usb_configuration *c)
+{
+	struct hidg_func_node *e;
+	int func = 0, status = 0;
+
+	if (gadget_is_otg(c->cdev->gadget)) {
+		c->descriptors = otg_desc;
+		c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
+	}
+
+	list_for_each_entry(e, &hidg_func_list, node) {
+		status = hidg_bind_config(c, e->func, func++);
+		if (status)
+			break;
+	}
+
+	return status;
+}
+
+static struct usb_configuration config_driver = {
+	.label			= "HID Gadget",
+	.bind			= do_config,
+	.bConfigurationValue	= 1,
+	/* .iConfiguration = DYNAMIC */
+	.bmAttributes		= USB_CONFIG_ATT_SELFPOWER,
+};
+
+/****************************** Gadget Bind ******************************/
+
+static int __init hid_bind(struct usb_composite_dev *cdev)
+{
+	struct usb_gadget *gadget = cdev->gadget;
+	struct list_head *tmp;
+	int status, gcnum, funcs = 0;
+
+	list_for_each(tmp, &hidg_func_list)
+		funcs++;
+
+	if (!funcs)
+		return -ENODEV;
+
+	/* set up HID */
+	status = ghid_setup(cdev->gadget, funcs);
+	if (status < 0)
+		return status;
+
+	gcnum = usb_gadget_controller_number(gadget);
+	if (gcnum >= 0)
+		device_desc.bcdDevice = cpu_to_le16(0x0300 | gcnum);
+	else
+		device_desc.bcdDevice = cpu_to_le16(0x0300 | 0x0099);
+
+
+	/* Allocate string descriptor numbers ... note that string
+	 * contents can be overridden by the composite_dev glue.
+	 */
+
+	/* device descriptor strings: manufacturer, product */
+	snprintf(manufacturer, sizeof manufacturer, "%s %s with %s",
+		init_utsname()->sysname, init_utsname()->release,
+		gadget->name);
+	status = usb_string_id(cdev);
+	if (status < 0)
+		return status;
+	strings_dev[STRING_MANUFACTURER_IDX].id = status;
+	device_desc.iManufacturer = status;
+
+	status = usb_string_id(cdev);
+	if (status < 0)
+		return status;
+	strings_dev[STRING_PRODUCT_IDX].id = status;
+	device_desc.iProduct = status;
+
+	/* register our configuration */
+	status = usb_add_config(cdev, &config_driver);
+	if (status < 0)
+		return status;
+
+	dev_info(&gadget->dev, DRIVER_DESC ", version: " DRIVER_VERSION "\n");
+
+	return 0;
+}
+
+static int __exit hid_unbind(struct usb_composite_dev *cdev)
+{
+	ghid_cleanup();
+	return 0;
+}
+
+static int __init hidg_plat_driver_probe(struct platform_device *pdev)
+{
+	struct hidg_func_descriptor *func = pdev->dev.platform_data;
+	struct hidg_func_node *entry;
+
+	if (!func) {
+		dev_err(&pdev->dev, "Platform data missing\n");
+		return -ENODEV;
+	}
+
+	entry = kzalloc(sizeof(*entry), GFP_KERNEL);
+	if (!entry)
+		return -ENOMEM;
+
+	entry->func = func;
+	list_add_tail(&entry->node, &hidg_func_list);
+
+	return 0;
+}
+
+static int __devexit hidg_plat_driver_remove(struct platform_device *pdev)
+{
+	struct hidg_func_node *e, *n;
+
+	list_for_each_entry_safe(e, n, &hidg_func_list, node) {
+		list_del(&e->node);
+		kfree(e);
+	}
+
+	return 0;
+}
+
+
+/****************************** Some noise ******************************/
+
+
+static struct usb_composite_driver hidg_driver = {
+	.name		= "g_hid",
+	.dev		= &device_desc,
+	.strings	= dev_strings,
+	.bind		= hid_bind,
+	.unbind		= __exit_p(hid_unbind),
+};
+
+static struct platform_driver hidg_plat_driver = {
+	.remove		= __devexit_p(hidg_plat_driver_remove),
+	.driver		= {
+		.owner	= THIS_MODULE,
+		.name	= "hidg",
+	},
+};
+
+
+MODULE_DESCRIPTION(DRIVER_DESC);
+MODULE_AUTHOR("Fabien Chouteau, Peter Korsgaard");
+MODULE_LICENSE("GPL");
+
+static int __init hidg_init(void)
+{
+	platform_driver_probe(&hidg_plat_driver, hidg_plat_driver_probe);
+	return usb_composite_register(&hidg_driver);
+}
+module_init(hidg_init);
+
+static void __exit hidg_cleanup(void)
+{
+	platform_driver_unregister(&hidg_plat_driver);
+	usb_composite_unregister(&hidg_driver);
+}
+module_exit(hidg_cleanup);

include/linux/usb/g_hid.h

+/*
+ * g_hid.h -- Header file for USB HID gadget driver
+ *
+ * Copyright (C) 2010 Fabien Chouteau <fabien.chouteau@barco.com>
+ *
+ * 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
+ */
+
+#ifndef __LINUX_USB_G_HID_H
+#define __LINUX_USB_G_HID_H
+
+struct hidg_func_descriptor {
+	unsigned char		subclass;
+	unsigned char		protocol;
+	unsigned short		report_length;
+	unsigned short		report_desc_length;
+	unsigned char		report_desc[];
+};
+
+#endif /* __LINUX_USB_G_HID_H */