kernel: backport raw-ip mode for newer QMI LTE modems

Backport support for raw-ip mode including all known fixes afterwards.

Newer LTE modems only tend to support this mode, which was only
introduced in kernel 4.5.

Also backport support for the Quectel EC2x LTE modem series which is
a very popular device.

No custom changes were needed in order to apply these patches.

Signed-off-by: Koen Vandeputte <koen.vandeputte@ncentric.com>

1 files changed, 97 insertions, 0 deletions

diff --git a/target/linux/generic/patches-4.4/099-0006-net-qmi_wwan-MDM9x30-specific-power-management.patch b/target/linux/generic/patches-4.4/099-0006-net-qmi_wwan-MDM9x30-specific-power-management.patch
new file mode 100644
index 0000000000..c26a86b270
--- /dev/null
+++ b/target/linux/generic/patches-4.4/099-0006-net-qmi_wwan-MDM9x30-specific-power-management.patch
@@ -0,0 +1,97 @@
+From 93725149794d3d418cf1eddcae60c7b536c5faa1 Mon Sep 17 00:00:00 2001
+From: =?UTF-8?q?Bj=C3=B8rn=20Mork?= <bjorn@mork.no>
+Date: Thu, 3 Dec 2015 19:24:18 +0100
+Subject: [PATCH] net: qmi_wwan: MDM9x30 specific power management
+MIME-Version: 1.0
+Content-Type: text/plain; charset=UTF-8
+Content-Transfer-Encoding: 8bit
+
+MDM9x30 based modems appear to go into a deeper sleep when
+suspended without "Remote Wakeup" enabled.  The QMI interface
+will not respond unless a "set DTR" control request is sent
+on resume. The effect is similar to a QMI_CTL SYNC request,
+resetting (some of) the firmware state.
+
+We allow userspace sessions to span multiple character device
+open/close sequences.  This means that userspace can depend
+on firmware state while both the netdev and the character
+device are closed.  We have disabled "needs_remote_wakeup" at
+this point to allow devices without remote wakeup support to
+be auto-suspended.
+
+To make sure the MDM9x30 keeps firmware state, we need to
+keep "needs_remote_wakeup" always set. We also need to
+issue a "set DTR" request to enable the QMI interface.
+
+Signed-off-by: Bjørn Mork <bjorn@mork.no>
+Signed-off-by: David S. Miller <davem@davemloft.net>
+---
+ drivers/net/usb/qmi_wwan.c | 38 ++++++++++++++++++++++++++++++++++++++
+ 1 file changed, 38 insertions(+)
+
+diff --git a/drivers/net/usb/qmi_wwan.c b/drivers/net/usb/qmi_wwan.c
+index 9a5be8b85186..fc9dd452a3b5 100644
+--- a/drivers/net/usb/qmi_wwan.c
++++ b/drivers/net/usb/qmi_wwan.c
+@@ -223,6 +223,20 @@ static int qmi_wwan_register_subdriver(struct usbnet *dev)
+ 	return rv;
+ }
+ 
++/* Send CDC SetControlLineState request, setting or clearing the DTR.
++ * "Required for Autoconnect and 9x30 to wake up" according to the
++ * GobiNet driver. The requirement has been verified on an MDM9230
++ * based Sierra Wireless MC7455
++ */
++static int qmi_wwan_change_dtr(struct usbnet *dev, bool on)
++{
++	u8 intf = dev->intf->cur_altsetting->desc.bInterfaceNumber;
++
++	return usbnet_write_cmd(dev, USB_CDC_REQ_SET_CONTROL_LINE_STATE,
++				USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE,
++				on ? 0x01 : 0x00, intf, NULL, 0);
++}
++
+ static int qmi_wwan_bind(struct usbnet *dev, struct usb_interface *intf)
+ {
+ 	int status = -1;
+@@ -280,6 +294,24 @@ static int qmi_wwan_bind(struct usbnet *dev, struct usb_interface *intf)
+ 		usb_driver_release_interface(driver, info->data);
+ 	}
+ 
++	/* disabling remote wakeup on MDM9x30 devices has the same
++	 * effect as clearing DTR. The device will not respond to QMI
++	 * requests until we set DTR again.  This is similar to a
++	 * QMI_CTL SYNC request, clearing a lot of firmware state
++	 * including the client ID allocations.
++	 *
++	 * Our usage model allows a session to span multiple
++	 * open/close events, so we must prevent the firmware from
++	 * clearing out state the clients might need.
++	 *
++	 * MDM9x30 is the first QMI chipset with USB3 support. Abuse
++	 * this fact to enable the quirk.
++	 */
++	if (le16_to_cpu(dev->udev->descriptor.bcdUSB) >= 0x0201) {
++		qmi_wwan_manage_power(dev, 1);
++		qmi_wwan_change_dtr(dev, true);
++	}
++
+ 	/* Never use the same address on both ends of the link, even if the
+ 	 * buggy firmware told us to. Or, if device is assigned the well-known
+ 	 * buggy firmware MAC address, replace it with a random address,
+@@ -307,6 +339,12 @@ static void qmi_wwan_unbind(struct usbnet *dev, struct usb_interface *intf)
+ 	if (info->subdriver && info->subdriver->disconnect)
+ 		info->subdriver->disconnect(info->control);
+ 
++	/* disable MDM9x30 quirk */
++	if (le16_to_cpu(dev->udev->descriptor.bcdUSB) >= 0x0201) {
++		qmi_wwan_change_dtr(dev, false);
++		qmi_wwan_manage_power(dev, 0);
++	}
++
+ 	/* allow user to unbind using either control or data */
+ 	if (intf == info->control)
+ 		other = info->data;
+-- 
+2.7.4
+