Re: Qualcomm rmnet driver and qmi_wwan

[Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>]

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> This sounds like a good idea. I probably won't have any time to look at
> this in the near future, though.  Sorry about that. Extremely 
> overloaded
> both at work and private right now...
> 
> But I trust that you and Daniele can work out something. Please keep me
> CCed, but don't expect timely replies.
> 

Hi Daniele

Can you try out the attached patch.
I have added a new sysfs attribute pass_through to be used in raw_ip 
mode
only. Once you attach rmnet devices on it, the rx_handler will be setup
and the packet will be processed by rmnet.

-- 
Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum,
a Linux Foundation Collaborative Project

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From bccfae3707af1be671fe55ea63123438f2dc38a8 Mon Sep 17 00:00:00 2001
From: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
Date: Fri, 8 Jun 2018 19:53:08 -0600
Subject: [PATCH] net: qmi_wwan: Add pass through mode

Pass through mode is to allow packets in MAP format to be passed
on to the stack. rmnet driver can be used to process and demultiplex
these packets. Note that pass through mode can be enabled when the
device is in raw ip mode only.

Signed-off-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
---
 drivers/net/usb/qmi_wwan.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)

diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
index 8e8b51f..f52a9be 100644
--- a/drivers/net/usb/qmi_wwan.c
+++ b/drivers/net/usb/qmi_wwan.c
@@ -59,6 +59,7 @@ struct qmi_wwan_state {
 enum qmi_wwan_flags {
 	QMI_WWAN_FLAG_RAWIP = 1 << 0,
 	QMI_WWAN_FLAG_MUX = 1 << 1,
+	QMI_WWAN_FLAG_PASS_THROUGH = 1 << 2,
 };
 
 enum qmi_wwan_quirks {
@@ -425,14 +426,80 @@ static ssize_t del_mux_store(struct device *d,  struct device_attribute *attr, c
 	return ret;
 }
 
+static ssize_t pass_through_show(struct device *d,
+				 struct device_attribute *attr,
+				 char *buf)
+{
+	struct usbnet *dev = netdev_priv(to_net_dev(d));
+	struct qmi_wwan_state *info;
+
+	info = (void *)&dev->data;
+	return sprintf(buf, "%c\n",
+		       info->flags & QMI_WWAN_FLAG_PASS_THROUGH ? 'Y' : 'N');
+}
+
+static ssize_t pass_through_store(struct device *d,
+				  struct device_attribute *attr,
+				  const char *buf, size_t len)
+{
+	struct usbnet *dev = netdev_priv(to_net_dev(d));
+	struct qmi_wwan_state *info;
+	bool enable;
+	int ret;
+
+	if (strtobool(buf, &enable))
+		return -EINVAL;
+
+	info = (void *)&dev->data;
+
+	/* no change? */
+	if (enable == (info->flags & QMI_WWAN_FLAG_PASS_THROUGH))
+		return len;
+
+	/* pass through mode can be set for raw ip devices only */
+	if (!(info->flags & QMI_WWAN_FLAG_RAWIP))
+		return -EINVAL;
+
+	if (!rtnl_trylock())
+		return restart_syscall();
+
+	/* we don't want to modify a running netdev */
+	if (netif_running(dev->net)) {
+		netdev_err(dev->net, "Cannot change a running device\n");
+		ret = -EBUSY;
+		goto err;
+	}
+
+	/* let other drivers deny the change */
+	ret = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev->net);
+	ret = notifier_to_errno(ret);
+	if (ret) {
+		netdev_err(dev->net, "Type change was refused\n");
+		goto err;
+	}
+
+	if (enable)
+		info->flags |= QMI_WWAN_FLAG_PASS_THROUGH;
+	else
+		info->flags &= ~QMI_WWAN_FLAG_PASS_THROUGH;
+	qmi_wwan_netdev_setup(dev->net);
+	call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev->net);
+	ret = len;
+err:
+	rtnl_unlock();
+	return ret;
+}
+
 static DEVICE_ATTR_RW(raw_ip);
 static DEVICE_ATTR_RW(add_mux);
 static DEVICE_ATTR_RW(del_mux);
+static DEVICE_ATTR_RW(pass_through);
 
 static struct attribute *qmi_wwan_sysfs_attrs[] = {
 	&dev_attr_raw_ip.attr,
 	&dev_attr_add_mux.attr,
 	&dev_attr_del_mux.attr,
+	&dev_attr_pass_through.attr,
 	NULL,
 };
 
@@ -479,6 +546,11 @@ static int qmi_wwan_rx_fixup(struct usbnet *dev, struct sk_buff *skb)
 	if (info->flags & QMI_WWAN_FLAG_MUX)
 		return qmimux_rx_fixup(dev, skb);
 
+	if (rawip && (info->flags & QMI_WWAN_FLAG_PASS_THROUGH)) {
+		skb->protocol = htons(ETH_P_MAP);
+		return (netif_rx(skb) == NET_RX_SUCCESS);
+	}
+
 	switch (skb->data[0] & 0xf0) {
 	case 0x40:
 		proto = htons(ETH_P_IP);
-- 
1.9.1