Re: [PATCH 07/10] usb: gadget: Add Android Composite Gadget driver

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On Tue, 27 Mar 2012 12:48:53 +0200, Andrzej Pietrasiewicz <andrzej.p@xxxxxxxxxxx> wrote:
From: Mike Lockwood <lockwood@xxxxxxxxxxx>

diff --git a/drivers/usb/gadget/android.c b/drivers/usb/gadget/android.c
@@ -0,0 +1,1065 @@
+/*
+ * Gadget Driver for Android
+ *
+ * Copyright (C) 2008 Google, Inc.
+ * Author: Mike Lockwood <lockwood@...>
+ *         Benoit Goby <benoit@...>

Uh?  What's up with “...”? Especially since I'd fill it with “google.com” and
as fas as I can teal, that would reach a different benoit@.

+ *
+ * This software is licensed under the terms of the GNU General Public
+ * License version 2, as published by the Free Software Foundation, and
+ * may be copied, distributed, and modified under those terms.
+ *
+ * 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.
+ *
+ */

+static void android_work(struct work_struct *data)
+{
+	struct android_dev *dev = container_of(data, struct android_dev, work);
+	struct usb_composite_dev *cdev = dev->cdev;
+	char *disconnected[2] = { "USB_STATE=DISCONNECTED", NULL };
+	char *connected[2]    = { "USB_STATE=CONNECTED", NULL };
+	char *configured[2]   = { "USB_STATE=CONFIGURED", NULL };

“static const char *” in the above three perhaps. I know, “const” will mess
with kobject_uevent_env(), but “static” should be fine.

+	char **uevent_envp = NULL;
+	unsigned long flags;
+
+	spin_lock_irqsave(&cdev->lock, flags);
+	if (cdev->config)
+		uevent_envp = configured;
+	else if (dev->connected != dev->sw_connected)
+		uevent_envp = dev->connected ? connected : disconnected;
+	dev->sw_connected = dev->connected;
+	spin_unlock_irqrestore(&cdev->lock, flags);
+
+	if (uevent_envp) {
+		kobject_uevent_env(&dev->dev->kobj, KOBJ_CHANGE, uevent_envp);
+		pr_info("%s: sent uevent %s\n", __func__, uevent_envp[0]);
+	} else {
+		pr_info("%s: did not send uevent (%d %d %p)\n", __func__,
+			 dev->connected, dev->sw_connected, cdev->config);
+	}
+}

+static ssize_t acm_instances_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct android_usb_function *f = dev_get_drvdata(dev);
+	struct acm_function_config *config = f->config;
+	int value;
+
+	sscanf(buf, "%d", &value);

ret = kstrtuint(buf, 10, &value);
if (ret)
	return ret;

+	if (value > MAX_ACM_INSTANCES)
+		value = MAX_ACM_INSTANCES;

	return -EINVAL; perhaps?

+	config->instances = value;
+	return size;
+}

+static ssize_t rndis_manufacturer_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct android_usb_function *f = dev_get_drvdata(dev);
+	struct rndis_function_config *config = f->config;
+
+	if (size >= sizeof(config->manufacturer))
+		return -EINVAL;
+	if (sscanf(buf, "%s", config->manufacturer) == 1)

Que? Why not memcpy() which makes much more sense?

+		return size;
+	return -1;
+}

+static ssize_t rndis_wceis_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct android_usb_function *f = dev_get_drvdata(dev);
+	struct rndis_function_config *config = f->config;
+	int value;
+
+	if (sscanf(buf, "%d", &value) == 1) {

Again, kstrtoi().

+		config->wceis = value;
+		return size;
+	}
+	return -EINVAL;
+}

+static ssize_t rndis_ethaddr_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct android_usb_function *f = dev_get_drvdata(dev);
+	struct rndis_function_config *rndis = f->config;
+	unsigned char tmp[6];
+	unsigned i;
+
+	if (sscanf(buf, "%hhx:%hhx:%hhx:%hhx:%hhx:%hhx",
+		tmp + 0, tmp + 1, tmp + 2, tmp + 3, tmp + 4, tmp + 5) !=
+	    ETH_ALEN)
+		return -EINVAL;
+	for (i = 0; i < ETH_ALEN; ++i)
+		rndis->ethaddr[i] = tmp[i];

memcpy()?

+	return ETH_ALEN;
+
+}

+static ssize_t rndis_vendorID_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct android_usb_function *f = dev_get_drvdata(dev);
+	struct rndis_function_config *config = f->config;
+	int value;
+
+	if (sscanf(buf, "%04x", &value) == 1) {

kstrtoint() or actually kstrotou16(buf, 16, &value).

+		config->vendorID = value;
+		return size;
+	}
+	return -EINVAL;
+}
+

+static ssize_t mass_storage_inquiry_show(struct device *dev,
+				struct device_attribute *attr, char *buf)
+{
+	struct android_usb_function *f = dev_get_drvdata(dev);
+	struct fsg_common *common = f->config;
+	return sprintf(buf, "%s\n", common->inquiry_string);
+}
+
+static ssize_t mass_storage_inquiry_store(struct device *dev,
+		struct device_attribute *attr, const char *buf, size_t size)
+{
+	struct android_usb_function *f = dev_get_drvdata(dev);
+	struct fsg_common *common = f->config;
+	if (size >= sizeof(common->inquiry_string))
+		return -EINVAL;
+	if (sscanf(buf, "%s", common->inquiry_string) != 1)
+		return -EINVAL;

memcpy() again.

+	return size;
+}
+
+static DEVICE_ATTR(inquiry_string, S_IRUGO | S_IWUSR,
+					mass_storage_inquiry_show,
+					mass_storage_inquiry_store);

Perhaps that should be moved to f_mass_storage.c somewhere?

But then again, this seem redundant, since one can set vendor_name,
product_name and release which are used to produce inquiry_string in
fsg_common_init().

I would rather if instead of this single sysfs entry, there were separate entries
for vendor_name, product_name and release.  But then again,

+static int android_init_functions(struct android_usb_function **functions,
+				  struct usb_composite_dev *cdev)
+{
+	struct android_dev *dev = _android_dev;
+	struct android_usb_function *f;
+	struct device_attribute **attrs;
+	struct device_attribute *attr;
+	int err;
+	int index = 0;
+
+	for (; (f = *functions++); index++) {
+		f->dev_name = kasprintf(GFP_KERNEL, "f_%s", f->name);

This may fail, no?

+		f->dev = device_create(android_class, dev->dev,
+				MKDEV(0, index), f, f->dev_name);
+		if (IS_ERR(f->dev)) {
+			pr_err("%s: Failed to create dev %s", __func__,
+							f->dev_name);
+			err = PTR_ERR(f->dev);
+			goto err_create;

Wouldn't that leak devices?  I don't see where the devices are destroyed
in error recovery path.

+		}
+
+		if (f->init) {
+			err = f->init(f, cdev);
+			if (err) {
+				pr_err("%s: Failed to init %s", __func__,
+								f->name);
+				goto err_out;
+			}
+		}
+
+		attrs = f->attributes;
+		if (attrs) {
+			while ((attr = *attrs++) && !err)
+				err = device_create_file(f->dev, attr);
+		}
+		if (err) {
+			pr_err("%s: Failed to create function %s attributes",
+					__func__, f->name);
+			goto err_out;
+		}
+	}
+	return 0;
+
+err_out:
+	device_destroy(android_class, f->dev->devt);
+err_create:
+	kfree(f->dev_name);
+	return err;
+}


+static int android_bind(struct usb_composite_dev *cdev)
+{
+	struct android_dev *dev = _android_dev;
+	struct usb_gadget	*gadget = cdev->gadget;
+	int			gcnum, id, ret;
+
+	/*
+	 * Start disconnected. Userspace will connect the gadget once
+	 * it is done configuring the functions.
+	 */
+	usb_gadget_disconnect(gadget);
+
+	ret = android_init_functions(dev->functions, cdev);
+	if (ret)
+		return ret;
+
+	/* Allocate string descriptor numbers ... note that string
+	 * contents can be overridden by the composite_dev glue.
+	 */
+	id = usb_string_id(cdev);
+	if (id < 0)
+		return id;
+	strings_dev[STRING_MANUFACTURER_IDX].id = id;
+	device_desc.iManufacturer = id;
+
+	id = usb_string_id(cdev);
+	if (id < 0)
+		return id;
+	strings_dev[STRING_PRODUCT_IDX].id = id;
+	device_desc.iProduct = id;
+
+	/* Default strings - should be updated by userspace */
+	strncpy(manufacturer_string, "Android", sizeof(manufacturer_string)-1);
+	strncpy(product_string, "Android", sizeof(product_string) - 1);

usb_composite_dev::iProduct and usb_composite_dev::iManufacturer are there so that
gadget drivers don't have to deal with those strings directly.  The above should
be removed from android composite gadget as it can be handled by regular composite
gadget.

+	strncpy(serial_string, "0123456789ABCDEF", sizeof(serial_string) - 1);
+
+	id = usb_string_id(cdev);
+	if (id < 0)
+		return id;
+	strings_dev[STRING_SERIAL_IDX].id = id;
+	device_desc.iSerialNumber = id;

iSerialNumber is also fishy in the same manner as iProduct and iManufacturer.

+
+	gcnum = usb_gadget_controller_number(gadget);
+	if (gcnum >= 0)
+		device_desc.bcdDevice = cpu_to_le16(0x0200 + gcnum);
+	else {
+		pr_warning("%s: controller '%s' not recognized\n",
+			longname, gadget->name);
+		device_desc.bcdDevice = __constant_cpu_to_le16(0x9999);
+	}
+
+	usb_gadget_set_selfpowered(gadget);
+	dev->cdev = cdev;
+
+	return 0;
+}

--
Best regards,                                         _     _
.o. | Liege of Serenely Enlightened Majesty of      o' \,=./ `o
..o | Computer Science,  Michał “mina86” Nazarewicz    (o o)
ooo +----<email/xmpp: mpn@xxxxxxxxxx>--------------ooO--(_)--Ooo--
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