Date: Tue, 16 Jan 2024 02:49:42 +0100
From: Michael Grzeschik <m.grzeschik@...gutronix.de>
To: Eric Van Hensbergen <ericvh@...nel.org>, 
 Latchesar Ionkov <lucho@...kov.net>, 
 Dominique Martinet <asmadeus@...ewreck.org>, 
 Christian Schoenebeck <linux_oss@...debyte.com>, 
 Jonathan Corbet <corbet@....net>, 
 Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc: v9fs@...ts.linux.dev, linux-doc@...r.kernel.org, 
 linux-kernel@...r.kernel.org, linux-usb@...r.kernel.org, 
 kernel@...gutronix.de, Michael Grzeschik <m.grzeschik@...gutronix.de>
Subject: [PATCH 2/3] usb: gadget: legacy: add 9pfs multi gadget

Add the newly introduced 9pfs transport gadget interface with an new
multi composed gadget together with acm and eem.

The usb forwarding can be started as follows:

Start the Network export via diod to localhost:

$ diod -f -n -d 0 -S -l 0.0.0.0:9999 -e $PWD

Start the python transport:

$ python p9_fwd.py

The gadget can then mount the exported filesystem:

$ mount -t 9p -o trans=usbg,aname=$PWD usb9pfs0 /mnt/9p

When using this legacy module, it is also possible to
mount the 9PFS usb dir as root filesystem. The kernel
commandline looks like this:

root=usb9pfs0 rootfstype=9p rootflags=trans=usbg,cache=loose,uname=root,access=0,dfltuid=0,dfltgid=0,aname=/path/to/rootfs

Signed-off-by: Michael Grzeschik <m.grzeschik@...gutronix.de>
---
 drivers/usb/gadget/legacy/9pfs.c   | 260 +++++++++++++++++++++++++++++++++++++
 drivers/usb/gadget/legacy/Kconfig  |  15 +++
 drivers/usb/gadget/legacy/Makefile |   2 +
 3 files changed, 277 insertions(+)

diff --git a/drivers/usb/gadget/legacy/9pfs.c b/drivers/usb/gadget/legacy/9pfs.c
new file mode 100644
index 0000000000000..e38fc89c89ded
--- /dev/null
+++ b/drivers/usb/gadget/legacy/9pfs.c
@@ -0,0 +1,260 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * usb9pfs.c -- Gadget usb9pfs
+ *
+ * Copyright (C) 2023 Michael Grzeschik
+ */
+
+/*
+ * Gadget usb9pfs only needs two bulk endpoints, and will use the usb9pfs usb
+ * transport to mount host filesystem via usb gadget.
+ */
+
+#include <linux/kernel.h>
+#include <linux/slab.h>
+#include <linux/device.h>
+#include <linux/module.h>
+#include <linux/err.h>
+#include <linux/usb/composite.h>
+#include <linux/netdevice.h>
+
+#include "u_eem.h"
+#include "u_ether.h"
+
+/*-------------------------------------------------------------------------*/
+USB_GADGET_COMPOSITE_OPTIONS();
+
+USB_ETHERNET_MODULE_PARAMETERS();
+
+/* Defines */
+
+#define DRIVER_VERSION_STR "v1.0"
+#define DRIVER_VERSION_NUM 0x1000
+
+#define DRIVER_DESC	"Composite Gadget (9P + ACM + NCM)"
+
+/*-------------------------------------------------------------------------*/
+
+#define DRIVER_VENDOR_NUM	0x1d6b		/* Linux Foundation */
+#define DRIVER_PRODUCT_NUM	0x0109		/* Linux-USB 9PFS Gadget */
+
+/*-------------------------------------------------------------------------*/
+
+static struct usb_device_descriptor device_desc = {
+	.bLength =		sizeof(device_desc),
+	.bDescriptorType =	USB_DT_DEVICE,
+
+	/* .bcdUSB = DYNAMIC */
+
+	.bDeviceClass =		USB_CLASS_MISC,
+	.bDeviceSubClass =	2,
+	.bDeviceProtocol =	1,
+
+	/* .bMaxPacketSize0 = f(hardware) */
+
+	/* Vendor and product id can be overridden by module parameters.  */
+	.idVendor =		cpu_to_le16(DRIVER_VENDOR_NUM),
+	.idProduct =		cpu_to_le16(DRIVER_PRODUCT_NUM),
+	/* .bcdDevice = f(hardware) */
+	/* .iManufacturer = DYNAMIC */
+	/* .iProduct = DYNAMIC */
+	/* NO SERIAL NUMBER */
+	/*.bNumConfigurations =	DYNAMIC*/
+};
+
+static const struct usb_descriptor_header *otg_desc[2];
+
+static struct usb_string strings_dev[] = {
+	[USB_GADGET_MANUFACTURER_IDX].s = "",
+	[USB_GADGET_PRODUCT_IDX].s = DRIVER_DESC,
+	[USB_GADGET_SERIAL_IDX].s = "",
+	{  }			/* 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,
+};
+
+static struct usb_configuration cdc_driver_conf = {
+	.label          = DRIVER_DESC,
+	.bConfigurationValue = 1,
+	/* .iConfiguration = DYNAMIC */
+	.bmAttributes   = USB_CONFIG_ATT_SELFPOWER,
+};
+
+static struct usb_function *f_9pfs;
+static struct usb_function_instance *fi_9pfs;
+
+static struct usb_function *f_acm;
+static struct usb_function_instance *fi_acm;
+
+static struct usb_function *f_eem;
+static struct usb_function_instance *fi_eem;
+
+static int cdc_do_config(struct usb_configuration *c)
+{
+	int ret;
+
+	if (gadget_is_otg(c->cdev->gadget)) {
+		c->descriptors = otg_desc;
+		c->bmAttributes |= USB_CONFIG_ATT_WAKEUP;
+	}
+
+	f_9pfs = usb_get_function(fi_9pfs);
+	if (IS_ERR(f_9pfs))
+		return PTR_ERR(f_9pfs);
+
+	ret = usb_add_function(c, f_9pfs);
+	if (ret < 0)
+		goto err_func_9pfs;
+
+	f_acm = usb_get_function(fi_acm);
+	if (IS_ERR(f_acm)) {
+		ret = PTR_ERR(f_acm);
+		goto err_func_acm;
+	}
+
+	ret = usb_add_function(c, f_acm);
+	if (ret)
+		goto err_conf;
+
+	f_eem = usb_get_function(fi_eem);
+	if (IS_ERR(f_eem)) {
+		ret = PTR_ERR(f_eem);
+		goto err_eem;
+	}
+
+	ret = usb_add_function(c, f_eem);
+	if (ret)
+		goto err_run;
+
+	return 0;
+err_run:
+	usb_put_function(f_eem);
+err_eem:
+	usb_remove_function(c, f_acm);
+err_conf:
+	usb_put_function(f_acm);
+err_func_acm:
+	usb_remove_function(c, f_9pfs);
+err_func_9pfs:
+	usb_put_function(f_9pfs);
+	return ret;
+}
+
+static int usb9pfs_bind(struct usb_composite_dev *cdev)
+{
+	struct f_eem_opts	*eem_opts = NULL;
+	int status;
+
+	fi_9pfs = usb_get_function_instance("usb9pfs");
+	if (IS_ERR(fi_9pfs))
+		return PTR_ERR(fi_9pfs);
+
+	/* set up serial link layer */
+	fi_acm = usb_get_function_instance("acm");
+	if (IS_ERR(fi_acm)) {
+		status = PTR_ERR(fi_acm);
+		goto err_conf_acm;
+	}
+
+	fi_eem = usb_get_function_instance("eem");
+	if (IS_ERR(fi_eem)) {
+		status = PTR_ERR(fi_eem);
+		goto err_conf_eem;
+	}
+
+	eem_opts = container_of(fi_eem, struct f_eem_opts, func_inst);
+
+	gether_set_qmult(eem_opts->net, qmult);
+	if (!gether_set_host_addr(eem_opts->net, host_addr))
+		pr_info("using host ethernet address: %s", host_addr);
+	if (!gether_set_dev_addr(eem_opts->net, dev_addr))
+		pr_info("using self ethernet address: %s", dev_addr);
+
+	/* Allocate string descriptor numbers ... note that string
+	 * contents can be overridden by the composite_dev glue.
+	 */
+	status = usb_string_ids_tab(cdev, strings_dev);
+	if (status < 0)
+		return status;
+
+	device_desc.iManufacturer = strings_dev[USB_GADGET_MANUFACTURER_IDX].id;
+	device_desc.iProduct = strings_dev[USB_GADGET_PRODUCT_IDX].id;
+	device_desc.iSerialNumber = strings_dev[USB_GADGET_SERIAL_IDX].id;
+
+	/* support OTG systems */
+	if (gadget_is_otg(cdev->gadget)) {
+		if (!otg_desc[0]) {
+			struct usb_descriptor_header *usb_desc;
+
+			usb_desc = usb_otg_descriptor_alloc(cdev->gadget);
+			if (!usb_desc) {
+				status = -ENOMEM;
+				goto err_conf_otg;
+			}
+			usb_otg_descriptor_init(cdev->gadget, usb_desc);
+			otg_desc[0] = usb_desc;
+			otg_desc[1] = NULL;
+		}
+	}
+
+	status = usb_add_config(cdev, &cdc_driver_conf, cdc_do_config);
+	if (status)
+		goto err_free_otg_desc;
+
+	usb_ep_autoconfig_reset(cdev->gadget);
+	usb_composite_overwrite_options(cdev, &coverwrite);
+
+	dev_info(&cdev->gadget->dev, DRIVER_DESC " version: " DRIVER_VERSION_STR "\n");
+
+	return 0;
+
+err_free_otg_desc:
+	kfree(otg_desc[0]);
+	otg_desc[0] = NULL;
+err_conf_otg:
+	usb_put_function_instance(fi_eem);
+err_conf_eem:
+	usb_put_function_instance(fi_acm);
+err_conf_acm:
+	usb_put_function_instance(fi_9pfs);
+	return status;
+}
+
+static int usb9pfs_unbind(struct usb_composite_dev *cdev)
+{
+	if (!IS_ERR_OR_NULL(f_eem))
+		usb_put_function(f_eem);
+	usb_put_function_instance(fi_eem);
+	if (!IS_ERR_OR_NULL(f_acm))
+		usb_put_function(f_acm);
+	usb_put_function_instance(fi_acm);
+	if (!IS_ERR_OR_NULL(f_9pfs))
+		usb_put_function(f_9pfs);
+	usb_put_function_instance(fi_9pfs);
+	kfree(otg_desc[0]);
+	otg_desc[0] = NULL;
+
+	return 0;
+}
+
+static struct usb_composite_driver usb9pfs_driver = {
+	.name		= "usb9pfs",
+	.dev		= &device_desc,
+	.strings	= dev_strings,
+	.max_speed	= USB_SPEED_SUPER,
+	.bind		= usb9pfs_bind,
+	.unbind		= usb9pfs_unbind,
+};
+
+module_usb_composite_driver(usb9pfs_driver);
+
+MODULE_AUTHOR("Michael Grzeschik");
+MODULE_LICENSE("GPL");
diff --git a/drivers/usb/gadget/legacy/Kconfig b/drivers/usb/gadget/legacy/Kconfig
index 0a7b382fbe27c..8569aecc1487b 100644
--- a/drivers/usb/gadget/legacy/Kconfig
+++ b/drivers/usb/gadget/legacy/Kconfig
@@ -62,6 +62,21 @@ config USB_ZERO
 	  Say "y" to link the driver statically, or "m" to build a
 	  dynamically linked module called "g_zero".
 
+config USB_9PFS
+	tristate "Gadget 9PFS"
+	select USB_LIBCOMPOSITE
+	select USB_U_SERIAL
+	select USB_U_ETHER
+	select USB_F_ACM
+	select USB_F_EEM
+	select USB_F_9PFS
+	select NET_9P
+	help
+	  9PFS Transport Layer
+
+	  Say "y" to link the driver statically, or "m" to build a
+	  dynamically linked module called "g_9pfs".
+
 config USB_ZERO_HNPTEST
 	bool "HNP Test Device"
 	depends on USB_ZERO && USB_OTG
diff --git a/drivers/usb/gadget/legacy/Makefile b/drivers/usb/gadget/legacy/Makefile
index 4d864bf82799d..99c098800d898 100644
--- a/drivers/usb/gadget/legacy/Makefile
+++ b/drivers/usb/gadget/legacy/Makefile
@@ -8,6 +8,7 @@ ccflags-y			+= -I$(srctree)/drivers/usb/gadget/udc/
 ccflags-y			+= -I$(srctree)/drivers/usb/gadget/function/
 
 g_zero-y			:= zero.o
+g_9pfs-y			:= 9pfs.o
 g_audio-y			:= audio.o
 g_ether-y			:= ether.o
 g_serial-y			:= serial.o
@@ -26,6 +27,7 @@ g_acm_ms-y			:= acm_ms.o
 g_tcm_usb_gadget-y		:= tcm_usb_gadget.o
 
 obj-$(CONFIG_USB_ZERO)		+= g_zero.o
+obj-$(CONFIG_USB_9PFS)		+= g_9pfs.o
 obj-$(CONFIG_USB_AUDIO)		+= g_audio.o
 obj-$(CONFIG_USB_ETH)		+= g_ether.o
 obj-$(CONFIG_USB_GADGETFS)	+= gadgetfs.o

-- 
2.39.2

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