The WWAN framework provides a unified way to handle WWAN/modems and
control port(s). It has initially been introduced to support MHI/PCI
modems, offering the same control protocols as the USB variants,
such as MBIM, QMI, AT... The WWAN framework exposes these control
protocols as character devices, similarly to cdc-wdm, but in a
bus agnostic fashion.
It would then make sense to migrate cdc-wdm to this unified framework
and register the USB modem control endpoints as standard WWAN control
ports.
Exposing cdc-wdm through WWAN framework normally maintains backward
compatibility, e.g:
$ qmicli --device-open-qmi -d /dev/wwan0p1QMI --dms-get-ids
instead of
$ qmicli --device-open-qmi -d /dev/cdc-wdm0 --dms-get-ids
However, some tools may rely on cdc-wdm driver/device name for device
detection. It is then safer to keep the 'legacy' cdc-wdm character
device to prevent any breakage. This is handled in this change by
API mutual exclusion, only one access method can be used at a time,
either cdc-wdm chardev or WWAN API.
Note that unknown channel types (other than MBIM, AT or MBIM) are not
registered to the WWAN framework.
Signed-off-by: Loic Poulain <loic.poulain@xxxxxxxxxx>
---
drivers/usb/class/cdc-wdm.c | 171 +++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 170 insertions(+), 1 deletion(-)
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index b59f146..7b798b5 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -23,6 +23,7 @@
#include <linux/poll.h>
#include <linux/usb.h>
#include <linux/usb/cdc.h>
+#include <linux/wwan.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>
#include <linux/usb/cdc-wdm.h>
@@ -55,6 +56,7 @@ MODULE_DEVICE_TABLE (usb, wdm_ids);
#define WDM_SUSPENDING 8
#define WDM_RESETTING 9
#define WDM_OVERFLOW 10
+#define WDM_WWAN_IN_USE 11
#define WDM_MAX 16
@@ -108,6 +110,7 @@ struct wdm_device {
int (*manage_power)(struct usb_interface *, int);
enum usb_cdc_wdm_type type;
+ struct wwan_port *wwanp;
};
static struct usb_driver wdm_driver;
@@ -203,7 +206,23 @@ static void wdm_in_callback(struct urb *urb)
if (desc->rerr == 0 && status != -EPIPE)
desc->rerr = status;
- if (length + desc->length > desc->wMaxCommand) {
+ if (test_bit(WDM_WWAN_IN_USE, &desc->flags)) {
+ struct wwan_port *port = desc->wwanp;
+ struct sk_buff *skb;
+
+ /* Forward data to WWAN port */
+ skb = alloc_skb(length, GFP_ATOMIC);
+ if (skb) {
+ memcpy(skb_put(skb, length), desc->inbuf, length);
+ wwan_port_rx(port, skb);
+ } else {
+ dev_err(&desc->intf->dev,
+ "Unable to alloc skb, response discarded\n");
+ }
+
+ /* inbuf has been copied, it is safe to check for outstanding data */
+ schedule_work(&desc->service_outs_intr);
+ } else if (length + desc->length > desc->wMaxCommand) {
/* The buffer would overflow */
set_bit(WDM_OVERFLOW, &desc->flags);
} else {
@@ -699,6 +718,11 @@ static int wdm_open(struct inode *inode, struct file *file)
goto out;
file->private_data = desc;
+ if (test_bit(WDM_WWAN_IN_USE, &desc->flags)) {
+ rv = -EBUSY;
+ goto out;
+ }
+
rv = usb_autopm_get_interface(desc->intf);
if (rv < 0) {
dev_err(&desc->intf->dev, "Error autopm - %d\n", rv);
@@ -794,6 +818,146 @@ static struct usb_class_driver wdm_class = {
.minor_base = WDM_MINOR_BASE,
};
+/* --- WWAN framework integration --- */
+#ifdef CONFIG_WWAN
+static int wdm_wwan_port_start(struct wwan_port *port)
+{
+ struct wdm_device *desc = wwan_port_get_drvdata(port);
+
+ /* The interface is both exposed via the WWAN framework and as a
+ * legacy usbmisc chardev. If chardev is already open, just fail
+ * to prevent concurrent usage. Otherwise, switch to WWAN mode.
+ */
+ mutex_lock(&wdm_mutex);
+ if (desc->count) {
+ mutex_unlock(&wdm_mutex);
+ return -EBUSY;
+ }
+ set_bit(WDM_WWAN_IN_USE, &desc->flags);
+ mutex_unlock(&wdm_mutex);
+
+ desc->manage_power(desc->intf, 1);
+
+ /* Start getting events */
+ usb_submit_urb(desc->validity, GFP_KERNEL);
+
+ /* tx is allowed */
+ wwan_port_txon(port);
+
+ return 0;
+}
+
+static void wdm_wwan_port_stop(struct wwan_port *port)
+{
+ struct wdm_device *desc = wwan_port_get_drvdata(port);
+
+ /* Stop all transfers and disable WWAN mode */
+ kill_urbs(desc);
+ desc->manage_power(desc->intf, 0);
+ clear_bit(WDM_READ, &desc->flags);
+ clear_bit(WDM_WWAN_IN_USE, &desc->flags);
+}
+
+static void wdm_wwan_port_tx_complete(struct urb *urb)
+{
+ struct sk_buff *skb = urb->context;
+ struct wwan_port *port = skb_shinfo(skb)->destructor_arg;
+
+ /* Allow new command transfer */
+ wwan_port_txon(port);
+ kfree_skb(skb);
+}
+
+static int wdm_wwan_port_tx(struct wwan_port *port, struct sk_buff *skb)
+{
+ struct wdm_device *desc = wwan_port_get_drvdata(port);
+ struct usb_interface *intf = desc->intf;
+ struct usb_ctrlrequest *req = desc->orq;
+ int rv;
+
+ rv = usb_autopm_get_interface(intf);
+ if (rv)
+ return rv;
+
+ usb_fill_control_urb(
+ desc->command,
+ interface_to_usbdev(intf),
+ usb_sndctrlpipe(interface_to_usbdev(intf), 0),
+ (unsigned char *)req,
+ skb->data,
+ skb->len,
+ wdm_wwan_port_tx_complete,
+ skb
+ );
+
+ req->bRequestType = (USB_DIR_OUT | USB_TYPE_CLASS | USB_RECIP_INTERFACE);
+ req->bRequest = USB_CDC_SEND_ENCAPSULATED_COMMAND;
+ req->wValue = 0;
+ req->wIndex = desc->inum;
+ req->wLength = cpu_to_le16(skb->len);
+
+ skb_shinfo(skb)->destructor_arg = port;
+
+ rv = usb_submit_urb(desc->command, GFP_KERNEL);
+ if (!rv) /* One transfer at a time, stop TX until URB completion */
+ wwan_port_txoff(port);
+
+ usb_autopm_put_interface(intf);
+
+ return rv;
+}
+
+static struct wwan_port_ops wdm_wwan_port_ops = {
+ .start = wdm_wwan_port_start,
+ .stop = wdm_wwan_port_stop,
+ .tx = wdm_wwan_port_tx,
+};
+
+static void wdm_wwan_init(struct wdm_device *desc)
+{
+ struct usb_interface *intf = desc->intf;
+ struct wwan_port *port;
+
+ switch (desc->type) {
+ case USB_CDC_WDM_MBIM:
+ port = wwan_create_port(&intf->dev, WWAN_PORT_MBIM,
+ &wdm_wwan_port_ops, desc);
+ break;
+ case USB_CDC_WDM_QMI:
+ port = wwan_create_port(&intf->dev, WWAN_PORT_QMI,
+ &wdm_wwan_port_ops, desc);
+ break;
+ case USB_CDC_WDM_AT:
+ port = wwan_create_port(&intf->dev, WWAN_PORT_AT,
+ &wdm_wwan_port_ops, desc);
+ break;
+ default:
+ dev_info(&intf->dev, "Unknown control protocol\n");
+ return;
+ }
+
+ if (IS_ERR(port)) {
+ dev_err(&intf->dev, "%s: Unable to create WWAN port\n",
+ dev_name(intf->usb_dev));
+ return;
+ }
+
+ desc->wwanp = port;
+}
+
+static void wdm_wwan_deinit(struct wdm_device *desc)
+{
+ if (!desc->wwanp)
+ return;
+
+ wwan_remove_port(desc->wwanp);
+ desc->wwanp = NULL;
+}
+#else /* CONFIG_WWAN */
+static void wdm_wwan_init(struct wdm_device *desc) {}
+static void wdm_wwan_deinit(struct wdm_device *desc) {}
+#endif /* CONFIG_WWAN */
+
/* --- error handling --- */
static void wdm_rxwork(struct work_struct *work)
{
@@ -937,6 +1101,9 @@ static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor
goto err;
else
dev_info(&intf->dev, "%s: USB WDM device\n", dev_name(intf->usb_dev));
+
+ wdm_wwan_init(desc);
+
out:
return rv;
err:
@@ -1034,6 +1201,8 @@ static void wdm_disconnect(struct usb_interface *intf)
desc = wdm_find_device(intf);
mutex_lock(&wdm_mutex);
+ wdm_wwan_deinit(desc);
+
/* the spinlock makes sure no new urbs are generated in the callbacks */
spin_lock_irqsave(&desc->iuspin, flags);
set_bit(WDM_DISCONNECTING, &desc->flags);
--
2.7.4
