net: huawei_cdc_ncm: Introduce the huawei_cdc_ncm driver

This driver supports devices using the NCM protocol as an encapsulation layer
for other protocols, like the E3131 Huawei 3G modem. This drivers approach was
heavily inspired by the qmi_wwan/cdc_mbim approach & code model.
Signed-off-by: NEnrico Mioso <mrkiko.rs@gmail.com>
Signed-off-by: NBjørn Mork <bjorn@mork.no>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

drivers/net/usb/Kconfig

@@ -242,6 +242,21 @@ config USB_NET_CDC_NCM
 	    * ST-Ericsson M343 HSPA Mobile Broadband Modem (reference design)
 	    * Ericsson F5521gw Mobile Broadband Module
 
+config USB_NET_HUAWEI_CDC_NCM
+	tristate "Huawei NCM embedded AT channel support"
+	depends on USB_USBNET
+	select USB_WDM
+	select USB_NET_CDC_NCM
+	help
+		This driver supports huawei-style NCM devices, that use NCM as a
+		transport for other protocols, usually an embedded AT channel.
+		Good examples are:
+		* Huawei E3131
+		* Huawei E3251
+
+		To compile this driver as a module, choose M here: the module will be
+		called huawei_cdc_ncm.ko.
+
 config USB_NET_CDC_MBIM
 	tristate "CDC MBIM support"
 	depends on USB_USBNET

drivers/net/usb/Makefile

@@ -32,6 +32,7 @@ obj-$(CONFIG_USB_IPHETH)	+= ipheth.o
 obj-$(CONFIG_USB_SIERRA_NET)	+= sierra_net.o
 obj-$(CONFIG_USB_NET_CX82310_ETH)	+= cx82310_eth.o
 obj-$(CONFIG_USB_NET_CDC_NCM)	+= cdc_ncm.o
+obj-$(CONFIG_USB_NET_HUAWEI_CDC_NCM)	+= huawei_cdc_ncm.o
 obj-$(CONFIG_USB_VL600)		+= lg-vl600.o
 obj-$(CONFIG_USB_NET_QMI_WWAN)	+= qmi_wwan.o
 obj-$(CONFIG_USB_NET_CDC_MBIM)	+= cdc_mbim.o

drivers/net/usb/huawei_cdc_ncm.c

+/* huawei_cdc_ncm.c - handles Huawei devices using the CDC NCM protocol as
+ * transport layer.
+ * Copyright (C) 2013	 Enrico Mioso <mrkiko.rs@gmail.com>
+ *
+ *
+ * ABSTRACT:
+ * This driver handles devices resembling the CDC NCM standard, but
+ * encapsulating another protocol inside it. An example are some Huawei 3G
+ * devices, exposing an embedded AT channel where you can set up the NCM
+ * connection.
+ * This code has been heavily inspired by the cdc_mbim.c driver, which is
+ * Copyright (c) 2012  Smith Micro Software, Inc.
+ * Copyright (c) 2012  Bjørn Mork <bjorn@mork.no>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * version 2 as published by the Free Software Foundation.
+ */
+
+#include <linux/module.h>
+#include <linux/netdevice.h>
+#include <linux/ethtool.h>
+#include <linux/if_vlan.h>
+#include <linux/ip.h>
+#include <linux/mii.h>
+#include <linux/usb.h>
+#include <linux/usb/cdc.h>
+#include <linux/usb/usbnet.h>
+#include <linux/usb/cdc-wdm.h>
+#include <linux/usb/cdc_ncm.h>
+
+/* Driver data */
+struct huawei_cdc_ncm_state {
+	struct cdc_ncm_ctx *ctx;
+	atomic_t pmcount;
+	struct usb_driver *subdriver;
+	struct usb_interface *control;
+	struct usb_interface *data;
+};
+
+static int huawei_cdc_ncm_manage_power(struct usbnet *usbnet_dev, int on)
+{
+	struct huawei_cdc_ncm_state *drvstate = (void *)&usbnet_dev->data;
+	int rv;
+
+	if ((on && atomic_add_return(1, &drvstate->pmcount) == 1) ||
+			(!on && atomic_dec_and_test(&drvstate->pmcount))) {
+		rv = usb_autopm_get_interface(usbnet_dev->intf);
+		usbnet_dev->intf->needs_remote_wakeup = on;
+		if (!rv)
+			usb_autopm_put_interface(usbnet_dev->intf);
+	}
+	return 0;
+}
+
+static int huawei_cdc_ncm_wdm_manage_power(struct usb_interface *intf,
+					   int status)
+{
+	struct usbnet *usbnet_dev = usb_get_intfdata(intf);
+
+	/* can be called while disconnecting */
+	if (!usbnet_dev)
+		return 0;
+
+	return huawei_cdc_ncm_manage_power(usbnet_dev, status);
+}
+
+
+static int huawei_cdc_ncm_bind(struct usbnet *usbnet_dev,
+			       struct usb_interface *intf)
+{
+	struct cdc_ncm_ctx *ctx;
+	struct usb_driver *subdriver = ERR_PTR(-ENODEV);
+	int ret = -ENODEV;
+	struct huawei_cdc_ncm_state *drvstate = (void *)&usbnet_dev->data;
+
+	/* altsetting should always be 1 for NCM devices - so we hard-coded
+	 * it here
+	 */
+	ret = cdc_ncm_bind_common(usbnet_dev, intf, 1);
+	if (ret)
+		goto err;
+
+	ctx = drvstate->ctx;
+
+	if (usbnet_dev->status)
+		/* CDC-WMC r1.1 requires wMaxCommand to be "at least 256
+		 * decimal (0x100)"
+		 */
+		subdriver = usb_cdc_wdm_register(ctx->control,
+						 &usbnet_dev->status->desc,
+						 256, /* wMaxCommand */
+						 huawei_cdc_ncm_wdm_manage_power);
+	if (IS_ERR(subdriver)) {
+		ret = PTR_ERR(subdriver);
+		cdc_ncm_unbind(usbnet_dev, intf);
+		goto err;
+	}
+
+	/* Prevent usbnet from using the status descriptor */
+	usbnet_dev->status = NULL;
+
+	drvstate->subdriver = subdriver;
+
+err:
+	return ret;
+}
+
+static void huawei_cdc_ncm_unbind(struct usbnet *usbnet_dev,
+				  struct usb_interface *intf)
+{
+	struct huawei_cdc_ncm_state *drvstate = (void *)&usbnet_dev->data;
+	struct cdc_ncm_ctx *ctx = drvstate->ctx;
+
+	if (drvstate->subdriver && drvstate->subdriver->disconnect)
+		drvstate->subdriver->disconnect(ctx->control);
+	drvstate->subdriver = NULL;
+
+	cdc_ncm_unbind(usbnet_dev, intf);
+}
+
+static int huawei_cdc_ncm_suspend(struct usb_interface *intf,
+				  pm_message_t message)
+{
+	int ret = 0;
+	struct usbnet *usbnet_dev = usb_get_intfdata(intf);
+	struct huawei_cdc_ncm_state *drvstate = (void *)&usbnet_dev->data;
+	struct cdc_ncm_ctx *ctx = drvstate->ctx;
+
+	if (ctx == NULL) {
+		ret = -ENODEV;
+		goto error;
+	}
+
+	ret = usbnet_suspend(intf, message);
+	if (ret < 0)
+		goto error;
+
+	if (intf == ctx->control &&
+		drvstate->subdriver &&
+		drvstate->subdriver->suspend)
+		ret = drvstate->subdriver->suspend(intf, message);
+	if (ret < 0)
+		usbnet_resume(intf);
+
+error:
+	return ret;
+}
+
+static int huawei_cdc_ncm_resume(struct usb_interface *intf)
+{
+	int ret = 0;
+	struct usbnet *usbnet_dev = usb_get_intfdata(intf);
+	struct huawei_cdc_ncm_state *drvstate = (void *)&usbnet_dev->data;
+	bool callsub;
+	struct cdc_ncm_ctx *ctx = drvstate->ctx;
+
+	/* should we call subdriver's resume function? */
+	callsub =
+		(intf == ctx->control &&
+		drvstate->subdriver &&
+		drvstate->subdriver->resume);
+
+	if (callsub)
+		ret = drvstate->subdriver->resume(intf);
+	if (ret < 0)
+		goto err;
+	ret = usbnet_resume(intf);
+	if (ret < 0 && callsub)
+		drvstate->subdriver->suspend(intf, PMSG_SUSPEND);
+err:
+	return ret;
+}
+
+static int huawei_cdc_ncm_check_connect(struct usbnet *usbnet_dev)
+{
+	struct cdc_ncm_ctx *ctx;
+
+	ctx = (struct cdc_ncm_ctx *)usbnet_dev->data[0];
+
+	if (ctx == NULL)
+		return 1; /* disconnected */
+
+	return !ctx->connected;
+}
+
+static const struct driver_info huawei_cdc_ncm_info = {
+	.description = "Huawei CDC NCM device",
+	.flags = FLAG_NO_SETINT | FLAG_MULTI_PACKET | FLAG_WWAN,
+	.bind = huawei_cdc_ncm_bind,
+	.unbind = huawei_cdc_ncm_unbind,
+	.check_connect = huawei_cdc_ncm_check_connect,
+	.manage_power = huawei_cdc_ncm_manage_power,
+	.rx_fixup = cdc_ncm_rx_fixup,
+	.tx_fixup = cdc_ncm_tx_fixup,
+};
+
+static const struct usb_device_id huawei_cdc_ncm_devs[] = {
+	/* Huawei NCM devices disguised as vendor specific */
+	{ USB_VENDOR_AND_INTERFACE_INFO(0x12d1, 0xff, 0x02, 0x16),
+	  .driver_info = (unsigned long)&huawei_cdc_ncm_info,
+	},
+	{ USB_VENDOR_AND_INTERFACE_INFO(0x12d1, 0xff, 0x02, 0x46),
+	  .driver_info = (unsigned long)&huawei_cdc_ncm_info,
+	},
+	{ USB_VENDOR_AND_INTERFACE_INFO(0x12d1, 0xff, 0x02, 0x76),
+	  .driver_info = (unsigned long)&huawei_cdc_ncm_info,
+	},
+
+	/* Terminating entry */
+	{
+	},
+};
+MODULE_DEVICE_TABLE(usb, huawei_cdc_ncm_devs);
+
+static struct usb_driver huawei_cdc_ncm_driver = {
+	.name = "huawei_cdc_ncm",
+	.id_table = huawei_cdc_ncm_devs,
+	.probe = usbnet_probe,
+	.disconnect = usbnet_disconnect,
+	.suspend = huawei_cdc_ncm_suspend,
+	.resume = huawei_cdc_ncm_resume,
+	.reset_resume = huawei_cdc_ncm_resume,
+	.supports_autosuspend = 1,
+	.disable_hub_initiated_lpm = 1,
+};
+module_usb_driver(huawei_cdc_ncm_driver);
+MODULE_AUTHOR("Enrico Mioso <mrkiko.rs@gmail.com>");
+MODULE_DESCRIPTION("USB CDC NCM host driver with encapsulated protocol support");
+MODULE_LICENSE("GPL");