This driver can be used as a subdriver of another USB driver, allowing
it to export a Device Managment interface consisting of a single interrupt
endpoint with no dedicated USB interface.
Some devices provide a Device Management function combined with a wwan
function in a single USB interface having three endpoints (bulk in/out
+ interrupt). If the interrupt endpoint is used exclusively for DM
notifications, then this driver can support that as a subdriver
provided that the wwan driver calls the appropriate entry points on
probe, suspend, resume, pre_reset, post_reset and disconnect.
The main driver must have full control over all interface related
settings, including the needs_remote_wakeup flag. A manage_power
function must be provided by the main driver.
A manage_power stub doing direct flag manipulation is used in normal
driver mode.
Signed-off-by: Bjørn Mork <bjorn@xxxxxxx>
---
drivers/usb/class/cdc-wdm.c | 63 ++++++++++++++++++++++++++++++++++++++++---
include/linux/usb/cdc-wdm.h | 19 +++++++++++++
2 files changed, 78 insertions(+), 4 deletions(-)
create mode 100644 include/linux/usb/cdc-wdm.h
diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c
index 46827373e..c6f6560 100644
--- a/drivers/usb/class/cdc-wdm.c
+++ b/drivers/usb/class/cdc-wdm.c
@@ -23,6 +23,7 @@
#include <linux/usb/cdc.h>
#include <asm/byteorder.h>
#include <asm/unaligned.h>
+#include <linux/usb/cdc-wdm.h>
/*
* Version Information
@@ -116,6 +117,7 @@ struct wdm_device {
int rerr;
struct list_head device_list;
+ int (*manage_power)(struct usb_interface *, int);
};
static struct usb_driver wdm_driver;
@@ -580,7 +582,6 @@ static int wdm_open(struct inode *inode, struct file *file)
dev_err(&desc->intf->dev, "Error autopm - %d\n", rv);
goto out;
}
- intf->needs_remote_wakeup = 1;
/* using write lock to protect desc->count */
mutex_lock(&desc->wlock);
@@ -597,6 +598,8 @@ static int wdm_open(struct inode *inode, struct file *file)
rv = 0;
}
mutex_unlock(&desc->wlock);
+ if (desc->count == 1)
+ desc->manage_power(intf, 1);
usb_autopm_put_interface(desc->intf);
out:
mutex_unlock(&wdm_mutex);
@@ -618,7 +621,7 @@ static int wdm_release(struct inode *inode, struct file *file)
dev_dbg(&desc->intf->dev, "wdm_release: cleanup");
kill_urbs(desc);
if (!test_bit(WDM_DISCONNECTING, &desc->flags))
- desc->intf->needs_remote_wakeup = 0;
+ desc->manage_power(desc->intf, 0);
}
mutex_unlock(&wdm_mutex);
return 0;
@@ -665,7 +668,8 @@ static void wdm_rxwork(struct work_struct *work)
/* --- hotplug --- */
-static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor *ep, u16 bufsize)
+static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor *ep,
+ u16 bufsize, int (*manage_power)(struct usb_interface *, int))
{
int rv = -ENOMEM;
struct wdm_device *desc;
@@ -750,6 +754,8 @@ static int wdm_create(struct usb_interface *intf, struct usb_endpoint_descriptor
desc
);
+ desc->manage_power = manage_power;
+
spin_lock(&wdm_device_list_lock);
list_add(&desc->device_list, &wdm_device_list);
spin_unlock(&wdm_device_list_lock);
@@ -766,6 +772,19 @@ err:
return rv;
}
+static int wdm_manage_power(struct usb_interface *intf, int on)
+{
+ /* need autopm_get/put here to ensure the usbcore sees the new value */
+ int rv = usb_autopm_get_interface(intf);
+ if (rv < 0)
+ goto err;
+
+ intf->needs_remote_wakeup = on;
+ usb_autopm_put_interface(intf);
+err:
+ return rv;
+}
+
static int wdm_probe(struct usb_interface *intf, const struct usb_device_id *id)
{
int rv = -EINVAL;
@@ -809,12 +828,48 @@ next_desc:
goto err;
ep = &iface->endpoint[0].desc;
- rv = wdm_create(intf, ep, maxcom);
+ rv = wdm_create(intf, ep, maxcom, &wdm_manage_power);
err:
return rv;
}
+/**
+ * usb_cdc_wdm_register - register a WDM subdriver
+ * @intf: usb interface the subdriver will associate with
+ * @ep: interrupt endpoint to monitor for notifications
+ * @bufsize: maximum message size to support for read/write
+ *
+ * Create WDM usb class character device and associate it with intf
+ * without binding, allowing another driver to manage the interface.
+ *
+ * The subdriver will manage the given interrupt endpoint exclusively
+ * and will issue control requests referring to the given intf. It
+ * will otherwise avoid interferring, and in particular not do
+ * usb_set_intfdata/usb_get_intfdata on intf.
+ *
+ * The return value is a pointer to the subdriver's struct usb_driver.
+ * The registering driver is responsible for calling this subdriver's
+ * disconnect, suspend, resume, pre_reset and post_reset methods from
+ * its own.
+ */
+struct usb_driver *usb_cdc_wdm_register(struct usb_interface *intf,
+ struct usb_endpoint_descriptor *ep,
+ int bufsize,
+ int (*manage_power)(struct usb_interface *, int))
+{
+ int rv = -EINVAL;
+
+ rv = wdm_create(intf, ep, bufsize, manage_power);
+ if (rv < 0)
+ goto err;
+
+ return &wdm_driver;
+err:
+ return ERR_PTR(rv);
+}
+EXPORT_SYMBOL(usb_cdc_wdm_register);
+
static void wdm_disconnect(struct usb_interface *intf)
{
struct wdm_device *desc;
diff --git a/include/linux/usb/cdc-wdm.h b/include/linux/usb/cdc-wdm.h
new file mode 100644
index 0000000..719c332
--- /dev/null
+++ b/include/linux/usb/cdc-wdm.h
@@ -0,0 +1,19 @@
+/*
+ * USB CDC Device Management subdriver
+ *
+ * Copyright (c) 2012 Bjørn Mork <bjorn@xxxxxxx>
+ *
+ * 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.
+ */
+
+#ifndef __LINUX_USB_CDC_WDM_H
+#define __LINUX_USB_CDC_WDM_H
+
+extern struct usb_driver *usb_cdc_wdm_register(struct usb_interface *intf,
+ struct usb_endpoint_descriptor *ep,
+ int bufsize,
+ int (*manage_power)(struct usb_interface *, int));
+
+#endif /* __LINUX_USB_CDC_WDM_H */
--
1.7.9
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