/*
 * Copyright (c) 2012  Bjørn Mork <bjorn@mork.no>
 *
 * The probing code is heavily inspired by cdc_ether, which is:
 * Copyright (C) 2003-2005 by David Brownell
 * Copyright (C) 2006 by Ole Andre Vadla Ravnas (ActiveSync)
 *
 * 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/mii.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>
#include <linux/usb/usbnet.h>
#include <linux/usb/cdc-wdm.h>

/* This driver supports wwan (3G/LTE/?) devices using a vendor
 * specific management protocol called Qualcomm MSM Interface (QMI) -
 * in addition to the more common AT commands over serial interface
 * management
 *
 * QMI is wrapped in CDC, using CDC encapsulated commands on the
 * control ("master") interface of a two-interface CDC Union
 * resembling standard CDC ECM.  The devices do not use the control
 * interface for any other CDC messages.  Most likely because the
 * management protocol is used in place of the standard CDC
 * notifications NOTIFY_NETWORK_CONNECTION and NOTIFY_SPEED_CHANGE
 *
 * Alternatively, control and data functions can be combined in a
 * single USB interface.
 *
 * Handling a protocol like QMI is out of the scope for any driver.
 * It is exported as a character device using the cdc-wdm driver as
 * a subdriver, enabling userspace applications ("modem managers") to
 * handle it.
 *
 * These devices may alternatively/additionally be configured using AT
 * commands on a serial interface
 */

/* driver specific data */
struct qmi_wwan_state {
	struct usb_driver *subdriver;
	atomic_t pmcount;
	unsigned long unused;
	struct usb_interface *control;
	struct usb_interface *data;
};

/* using a counter to merge subdriver requests with our own into a combined state */
static int qmi_wwan_manage_power(struct usbnet *dev, int on)
{
	struct qmi_wwan_state *info = (void *)&dev->data;
	int rv = 0;

	dev_dbg(&dev->intf->dev, "%s() pmcount=%d, on=%d\n", __func__, atomic_read(&info->pmcount), on);

	if ((on && atomic_add_return(1, &info->pmcount) == 1) || (!on && atomic_dec_and_test(&info->pmcount))) {
		/* need autopm_get/put here to ensure the usbcore sees the new value */
		rv = usb_autopm_get_interface(dev->intf);
		if (rv < 0)
			goto err;
		dev->intf->needs_remote_wakeup = on;
		usb_autopm_put_interface(dev->intf);
	}
err:
	return rv;
}

static int qmi_wwan_cdc_wdm_manage_power(struct usb_interface *intf, int on)
{
	struct usbnet *dev = usb_get_intfdata(intf);

	/* can be called while disconnecting */
	if (!dev)
		return 0;
	return qmi_wwan_manage_power(dev, on);
}

/* collect all three endpoints and register subdriver */
static int qmi_wwan_register_subdriver(struct usbnet *dev)
{
	int rv;
	struct usb_driver *subdriver = NULL;
	struct qmi_wwan_state *info = (void *)&dev->data;

	/* collect bulk endpoints */
	rv = usbnet_get_endpoints(dev, info->data);
	if (rv < 0)
		goto err;

	/* update status endpoint if separate control interface */
	if (info->control != info->data)
		dev->status = &info->control->cur_altsetting->endpoint[0];

	/* require interrupt endpoint for subdriver */
	if (!dev->status) {
		rv = -EINVAL;
		goto err;
	}

	/* for subdriver power management */
	atomic_set(&info->pmcount, 0);

	/* register subdriver */
	subdriver = usb_cdc_wdm_register(info->control, &dev->status->desc, 512, &qmi_wwan_cdc_wdm_manage_power);
	if (IS_ERR(subdriver)) {
		dev_err(&info->control->dev, "subdriver registration failed\n");
		rv = PTR_ERR(subdriver);
		goto err;
	}

	/* prevent usbnet from using status endpoint */
	dev->status = NULL;

	/* save subdriver struct for suspend/resume wrappers */
	info->subdriver = subdriver;

err:
	return rv;
}

static int qmi_wwan_bind(struct usbnet *dev, struct usb_interface *intf)
{
	int status = -1;
	u8 *buf = intf->cur_altsetting->extra;
	int len = intf->cur_altsetting->extralen;
	struct usb_interface_descriptor *desc = &intf->cur_altsetting->desc;
	struct usb_cdc_union_desc *cdc_union = NULL;
	struct usb_cdc_ether_desc *cdc_ether = NULL;
	u32 found = 0;
	struct usb_driver *driver = driver_of(intf);
	struct qmi_wwan_state *info = (void *)&dev->data;

	BUILD_BUG_ON((sizeof(((struct usbnet *)0)->data) < sizeof(struct qmi_wwan_state)));

	/* require a single interrupt status endpoint for subdriver */
	if (intf->cur_altsetting->desc.bNumEndpoints != 1)
		goto err;

	while (len > 3) {
		struct usb_descriptor_header *h = (void *)buf;

		/* ignore any misplaced descriptors */
		if (h->bDescriptorType != USB_DT_CS_INTERFACE)
			goto next_desc;

		/* buf[2] is CDC descriptor subtype */
		switch (buf[2]) {
		case USB_CDC_HEADER_TYPE:
			if (found & 1 << USB_CDC_HEADER_TYPE) {
				dev_dbg(&intf->dev, "extra CDC header\n");
				goto err;
			}
			if (h->bLength != sizeof(struct usb_cdc_header_desc)) {
				dev_dbg(&intf->dev, "CDC header len %u\n", h->bLength);
				goto err;
			}
			break;
		case USB_CDC_UNION_TYPE:
			if (found & 1 << USB_CDC_UNION_TYPE) {
				dev_dbg(&intf->dev, "extra CDC union\n");
				goto err;
			}
			if (h->bLength != sizeof(struct usb_cdc_union_desc)) {
				dev_dbg(&intf->dev, "CDC union len %u\n", h->bLength);
				goto err;
			}
			cdc_union = (struct usb_cdc_union_desc *)buf;
			break;
		case USB_CDC_ETHERNET_TYPE:
			if (found & 1 << USB_CDC_ETHERNET_TYPE) {
				dev_dbg(&intf->dev, "extra CDC ether\n");
				goto err;
			}
			if (h->bLength != sizeof(struct usb_cdc_ether_desc)) {
				dev_dbg(&intf->dev, "CDC ether len %u\n",  h->bLength);
				goto err;
			}
			cdc_ether = (struct usb_cdc_ether_desc *)buf;
			break;
		}

		/*
		 * Remember which CDC functional descriptors we've seen.  Works
		 * for all types we care about, of which USB_CDC_ETHERNET_TYPE
		 * (0x0f) is the highest numbered
		 */
		if (buf[2] < 32)
			found |= 1 << buf[2];

next_desc:
		len -= h->bLength;
		buf += h->bLength;
	}

	/* did we find all the required ones? */
	if (!(found & (1 << USB_CDC_HEADER_TYPE)) ||
	    !(found & (1 << USB_CDC_UNION_TYPE))) {
		dev_err(&intf->dev, "CDC functional descriptors missing\n");
		goto err;
	}

	/* verify CDC Union */
	if (desc->bInterfaceNumber != cdc_union->bMasterInterface0) {
		dev_err(&intf->dev, "bogus CDC Union: master=%u\n", cdc_union->bMasterInterface0);
		goto err;
	}

	/* need to save these for unbind */
	info->control = intf;
	info->data = usb_ifnum_to_if(dev->udev,	cdc_union->bSlaveInterface0);
	if (!info->data) {
		dev_err(&intf->dev, "bogus CDC Union: slave=%u\n", cdc_union->bSlaveInterface0);
		goto err;
	}

	/* errors aren't fatal - we can live with the dynamic address */
	if (cdc_ether) {
		dev->hard_mtu = le16_to_cpu(cdc_ether->wMaxSegmentSize);
		usbnet_get_ethernet_addr(dev, cdc_ether->iMACAddress);
	}

	/* claim data interface and set it up */
	status = usb_driver_claim_interface(driver, info->data, dev);
	if (status < 0)
		goto err;

	status = qmi_wwan_register_subdriver(dev);
	if (status < 0) {
		usb_set_intfdata(info->data, NULL);
		usb_driver_release_interface(driver, info->data);
	}

err:
	return status;
}

/* Some devices combine the "control" and "data" functions into a
 * single interface with all three endpoints: interrupt + bulk in and
 * out
 */
static int qmi_wwan_bind_shared(struct usbnet *dev, struct usb_interface *intf)
{
	struct qmi_wwan_state *info = (void *)&dev->data;

	/*  control and data is shared */
	info->control = intf;
	info->data = intf;
	return qmi_wwan_register_subdriver(dev);
}

static void qmi_wwan_unbind(struct usbnet *dev, struct usb_interface *intf)
{
	struct qmi_wwan_state *info = (void *)&dev->data;
	struct usb_driver *driver = driver_of(intf);
	struct usb_interface *other;

	if (info->subdriver && info->subdriver->disconnect)
		info->subdriver->disconnect(info->control);

	/* allow user to unbind using either control or data */
	if (intf == info->control)
		other = info->data;
	else
		other = info->control;

	/* only if not shared */
	if (other && intf != other) {
		usb_set_intfdata(other, NULL);
		usb_driver_release_interface(driver, other);
	}

	info->subdriver = NULL;
	info->data = NULL;
	info->control = NULL;
}

/* suspend/resume wrappers calling both usbnet and the cdc-wdm
 * subdriver if present.
 *
 * NOTE: cdc-wdm also supports pre/post_reset, but we cannot provide
 * wrappers for those without adding usbnet reset support first.
 */
static int qmi_wwan_suspend(struct usb_interface *intf, pm_message_t message)
{
	struct usbnet *dev = usb_get_intfdata(intf);
	struct qmi_wwan_state *info = (void *)&dev->data;
	int ret;

	ret = usbnet_suspend(intf, message);
	if (ret < 0)
		goto err;

	if (intf == info->control && info->subdriver && info->subdriver->suspend)
		ret = info->subdriver->suspend(intf, message);
	if (ret < 0)
		usbnet_resume(intf);
err:
	return ret;
}

static int qmi_wwan_resume(struct usb_interface *intf)
{
	struct usbnet *dev = usb_get_intfdata(intf);
	struct qmi_wwan_state *info = (void *)&dev->data;
	int ret = 0;
	bool callsub = (intf == info->control && info->subdriver && info->subdriver->resume);

	if (callsub)
		ret = info->subdriver->resume(intf);
	if (ret < 0)
		goto err;
	ret = usbnet_resume(intf);
	if (ret < 0 && callsub && info->subdriver->suspend)
		info->subdriver->suspend(intf, PMSG_SUSPEND);
err:
	return ret;
}

static const struct driver_info	qmi_wwan_info = {
	.description	= "WWAN/QMI device",
	.flags		= FLAG_WWAN,
	.bind		= qmi_wwan_bind,
	.unbind		= qmi_wwan_unbind,
	.manage_power	= qmi_wwan_manage_power,
};

static const struct driver_info	qmi_wwan_shared = {
	.description	= "WWAN/QMI device",
	.flags		= FLAG_WWAN,
	.bind		= qmi_wwan_bind_shared,
	.unbind		= qmi_wwan_unbind,
	.manage_power	= qmi_wwan_manage_power,
};

#define HUAWEI_VENDOR_ID	0x12D1

/* map QMI/wwan function by a fixed interface number */
#define QMI_FIXED_INTF(vend, prod, num) \
	USB_DEVICE_INTERFACE_NUMBER(vend, prod, num), \
	.driver_info = (unsigned long)&qmi_wwan_shared

/* Gobi 1000 QMI/wwan interface number is 3 according to qcserial */
#define QMI_GOBI1K_DEVICE(vend, prod) \
	QMI_FIXED_INTF(vend, prod, 3)

/* Gobi 2000/3000 QMI/wwan interface number is 0 according to qcserial */
#define QMI_GOBI_DEVICE(vend, prod) \
	QMI_FIXED_INTF(vend, prod, 0)

static const struct usb_device_id products[] = {
	/* 1. CDC ECM like devices match on the control interface */
	{	/* Huawei E392, E398 and possibly others sharing both device id and more... */
		USB_VENDOR_AND_INTERFACE_INFO(HUAWEI_VENDOR_ID, USB_CLASS_VENDOR_SPEC, 1, 9),
		.driver_info        = (unsigned long)&qmi_wwan_info,
	},
	{	/* Vodafone/Huawei K5005 (12d1:14c8) and similar modems */
		USB_VENDOR_AND_INTERFACE_INFO(HUAWEI_VENDOR_ID, USB_CLASS_VENDOR_SPEC, 1, 57),
		.driver_info        = (unsigned long)&qmi_wwan_info,
	},

	/* 2. Combined interface devices matching on class+protocol */
	{	/* Huawei E367 and possibly others in "Windows mode" */
		USB_VENDOR_AND_INTERFACE_INFO(HUAWEI_VENDOR_ID, USB_CLASS_VENDOR_SPEC, 1, 7),
		.driver_info        = (unsigned long)&qmi_wwan_info,
	},
	{	/* Huawei E392, E398 and possibly others in "Windows mode" */
		USB_VENDOR_AND_INTERFACE_INFO(HUAWEI_VENDOR_ID, USB_CLASS_VENDOR_SPEC, 1, 17),
		.driver_info        = (unsigned long)&qmi_wwan_shared,
	},
	{	/* Pantech UML290, P4200 and more */
		USB_VENDOR_AND_INTERFACE_INFO(0x106c, USB_CLASS_VENDOR_SPEC, 0xf0, 0xff),
		.driver_info        = (unsigned long)&qmi_wwan_shared,
	},
	{	/* Pantech UML290 - newer firmware */
		USB_VENDOR_AND_INTERFACE_INFO(0x106c, USB_CLASS_VENDOR_SPEC, 0xf1, 0xff),
		.driver_info        = (unsigned long)&qmi_wwan_shared,
	},

	/* 3. Combined interface devices matching on interface number */
	{QMI_FIXED_INTF(0x19d2, 0x0055, 1)},	/* ZTE (Vodafone) K3520-Z */
	{QMI_FIXED_INTF(0x19d2, 0x0063, 4)},	/* ZTE (Vodafone) K3565-Z */
	{QMI_FIXED_INTF(0x19d2, 0x0104, 4)},	/* ZTE (Vodafone) K4505-Z */
	{QMI_FIXED_INTF(0x19d2, 0x0157, 5)},	/* ZTE MF683 */
	{QMI_FIXED_INTF(0x19d2, 0x0167, 4)},	/* ZTE MF820D */
	{QMI_FIXED_INTF(0x19d2, 0x0326, 4)},	/* ZTE MF821D */
	{QMI_FIXED_INTF(0x19d2, 0x1008, 4)},	/* ZTE (Vodafone) K3570-Z */
	{QMI_FIXED_INTF(0x19d2, 0x1010, 4)},	/* ZTE (Vodafone) K3571-Z */
	{QMI_FIXED_INTF(0x19d2, 0x1018, 3)},	/* ZTE (Vodafone) K5006-Z */
	{QMI_FIXED_INTF(0x19d2, 0x1402, 2)},	/* ZTE MF60 */
	{QMI_FIXED_INTF(0x19d2, 0x2002, 4)},	/* ZTE (Vodafone) K3765-Z */
	{QMI_FIXED_INTF(0x0f3d, 0x68a2, 8)},    /* Sierra Wireless MC7700 */
	{QMI_FIXED_INTF(0x114f, 0x68a2, 8)},    /* Sierra Wireless MC7750 */
	{QMI_FIXED_INTF(0x1199, 0x68a2, 8)},	/* Sierra Wireless MC7710 in QMI mode */
	{QMI_FIXED_INTF(0x1199, 0x68a2, 19)},	/* Sierra Wireless MC7710 in QMI mode */
	{QMI_FIXED_INTF(0x1199, 0x901c, 8)},    /* Sierra Wireless EM7700 */

	/* 4. Gobi 1000 devices */
	{QMI_GOBI1K_DEVICE(0x05c6, 0x9212)},	/* Acer Gobi Modem Device */
	{QMI_GOBI1K_DEVICE(0x03f0, 0x1f1d)},	/* HP un2400 Gobi Modem Device */
	{QMI_GOBI1K_DEVICE(0x04da, 0x250d)},	/* Panasonic Gobi Modem device */
	{QMI_GOBI1K_DEVICE(0x413c, 0x8172)},	/* Dell Gobi Modem device */
	{QMI_GOBI1K_DEVICE(0x1410, 0xa001)},	/* Novatel Gobi Modem device */
	{QMI_GOBI1K_DEVICE(0x0b05, 0x1776)},	/* Asus Gobi Modem device */
	{QMI_GOBI1K_DEVICE(0x19d2, 0xfff3)},	/* ONDA Gobi Modem device */
	{QMI_GOBI1K_DEVICE(0x05c6, 0x9001)},	/* Generic Gobi Modem device */
	{QMI_GOBI1K_DEVICE(0x05c6, 0x9002)},	/* Generic Gobi Modem device */
	{QMI_GOBI1K_DEVICE(0x05c6, 0x9202)},	/* Generic Gobi Modem device */
	{QMI_GOBI1K_DEVICE(0x05c6, 0x9203)},	/* Generic Gobi Modem device */
	{QMI_GOBI1K_DEVICE(0x05c6, 0x9222)},	/* Generic Gobi Modem device */
	{QMI_GOBI1K_DEVICE(0x05c6, 0x9009)},	/* Generic Gobi Modem device */

	/* 5. Gobi 2000 and 3000 devices */
	{QMI_GOBI_DEVICE(0x413c, 0x8186)},	/* Dell Gobi 2000 Modem device (N0218, VU936) */
	{QMI_GOBI_DEVICE(0x413c, 0x8194)},	/* Dell Gobi 3000 Composite */
	{QMI_GOBI_DEVICE(0x05c6, 0x920b)},	/* Generic Gobi 2000 Modem device */
	{QMI_GOBI_DEVICE(0x05c6, 0x920d)},	/* Gobi 3000 Composite */
	{QMI_GOBI_DEVICE(0x05c6, 0x9225)},	/* Sony Gobi 2000 Modem device (N0279, VU730) */
	{QMI_GOBI_DEVICE(0x05c6, 0x9245)},	/* Samsung Gobi 2000 Modem device (VL176) */
	{QMI_GOBI_DEVICE(0x03f0, 0x251d)},	/* HP Gobi 2000 Modem device (VP412) */
	{QMI_GOBI_DEVICE(0x05c6, 0x9215)},	/* Acer Gobi 2000 Modem device (VP413) */
	{QMI_GOBI_DEVICE(0x05c6, 0x9265)},	/* Asus Gobi 2000 Modem device (VR305) */
	{QMI_GOBI_DEVICE(0x05c6, 0x9235)},	/* Top Global Gobi 2000 Modem device (VR306) */
	{QMI_GOBI_DEVICE(0x05c6, 0x9275)},	/* iRex Technologies Gobi 2000 Modem device (VR307) */
	{QMI_GOBI_DEVICE(0x1199, 0x68a5)},	/* Sierra Wireless Modem */
	{QMI_GOBI_DEVICE(0x1199, 0x68a9)},	/* Sierra Wireless Modem */
	{QMI_GOBI_DEVICE(0x1199, 0x9001)},	/* Sierra Wireless Gobi 2000 Modem device (VT773) */
	{QMI_GOBI_DEVICE(0x1199, 0x9002)},	/* Sierra Wireless Gobi 2000 Modem device (VT773) */
	{QMI_GOBI_DEVICE(0x1199, 0x9003)},	/* Sierra Wireless Gobi 2000 Modem device (VT773) */
	{QMI_GOBI_DEVICE(0x1199, 0x9004)},	/* Sierra Wireless Gobi 2000 Modem device (VT773) */
	{QMI_GOBI_DEVICE(0x1199, 0x9005)},	/* Sierra Wireless Gobi 2000 Modem device (VT773) */
	{QMI_GOBI_DEVICE(0x1199, 0x9006)},	/* Sierra Wireless Gobi 2000 Modem device (VT773) */
	{QMI_GOBI_DEVICE(0x1199, 0x9007)},	/* Sierra Wireless Gobi 2000 Modem device (VT773) */
	{QMI_GOBI_DEVICE(0x1199, 0x9008)},	/* Sierra Wireless Gobi 2000 Modem device (VT773) */
	{QMI_GOBI_DEVICE(0x1199, 0x9009)},	/* Sierra Wireless Gobi 2000 Modem device (VT773) */
	{QMI_GOBI_DEVICE(0x1199, 0x900a)},	/* Sierra Wireless Gobi 2000 Modem device (VT773) */
	{QMI_GOBI_DEVICE(0x1199, 0x9011)},	/* Sierra Wireless Gobi 2000 Modem device (MC8305) */
	{QMI_FIXED_INTF(0x1199, 0x9011, 5)},	/* alternate interface number!? */
	{QMI_GOBI_DEVICE(0x16d8, 0x8002)},	/* CMDTech Gobi 2000 Modem device (VU922) */
	{QMI_GOBI_DEVICE(0x05c6, 0x9205)},	/* Gobi 2000 Modem device */
	{QMI_GOBI_DEVICE(0x1199, 0x9013)},	/* Sierra Wireless Gobi 3000 Modem device (MC8355) */
	{QMI_GOBI_DEVICE(0x03f0, 0x371d)},	/* HP un2430 Mobile Broadband Module */
	{QMI_GOBI_DEVICE(0x1199, 0x9015)},	/* Sierra Wireless Gobi 3000 Modem device */
	{QMI_GOBI_DEVICE(0x1199, 0x9019)},	/* Sierra Wireless Gobi 3000 Modem device */
	{QMI_GOBI_DEVICE(0x1199, 0x901b)},	/* Sierra Wireless MC7770 */
	{QMI_GOBI_DEVICE(0x12d1, 0x14f1)},	/* Sony Gobi 3000 Composite */
	{QMI_GOBI_DEVICE(0x1410, 0xa021)},	/* Foxconn Gobi 3000 Modem device (Novatel E396) */

	{ }					/* END */
};
MODULE_DEVICE_TABLE(usb, products);

static int qmi_wwan_probe(struct usb_interface *intf, const struct usb_device_id *prod)
{
	struct usb_device_id *id = (struct usb_device_id *)prod;

	/* Workaround to enable dynamic IDs.  This disables usbnet
	 * blacklisting functionality.  Which, if required, can be
	 * reimplemented here by using a magic "blacklist" value
	 * instead of 0 in the static device id table
	 */
	if (!id->driver_info) {
		dev_dbg(&intf->dev, "setting defaults for dynamic device id\n");
		id->driver_info = (unsigned long)&qmi_wwan_shared;
	}

	return usbnet_probe(intf, id);
}

static struct usb_driver qmi_wwan_driver = {
	.name		      = "qmi_wwan",
	.id_table	      = products,
	.probe		      = qmi_wwan_probe,
	.disconnect	      = usbnet_disconnect,
	.suspend	      = qmi_wwan_suspend,
	.resume		      =	qmi_wwan_resume,
	.reset_resume         = qmi_wwan_resume,
	.supports_autosuspend = 1,
	.disable_hub_initiated_lpm = 1,
};

module_usb_driver(qmi_wwan_driver);

MODULE_AUTHOR("Bjørn Mork <bjorn@mork.no>");
MODULE_DESCRIPTION("Qualcomm MSM Interface (QMI) WWAN driver");
MODULE_LICENSE("GPL");