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usb: cdc-wdm: adding usb_cdc_wdm_register subdriver support 

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@mork.no>
Acked-by: Oliver Neukum <oneukum@suse.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Bjørn Mork 2012-03-06 17:29:22 +01:00 committed by Greg Kroah-Hartman
parent b0c1386080
commit 3cc3615749
2 changed files with 78 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

63
drivers/usb/class/cdc-wdm.c
View File

@ -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;

19
include/linux/usb/cdc-wdm.h Normal file
View File

@ -0,0 +1,19 @@
/*
* USB CDC Device Management subdriver
*
* Copyright (c) 2012 Bjørn Mork <bjorn@mork.no>
*
* 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 */