korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-23 12:14:10 +08:00
Code Issues Packages Projects Releases Wiki Activity

usb: gadget: f_fs: expose ready state in configfs

Browse Source 
When a USB gadget is configured through configfs with 1 or more f_fs
functions, then the logic setting up the gadget configuration has to wait
until the user space code (typically separate applications) responsible for
those functions have written their descriptors before the gadget can be
activated.

The f_fs instance already knows if this has been done, so expose it through
a "ready" attribute in configfs for easier synchronization.

Signed-off-by: Peter Korsgaard <peter@korsgaard.com>
Link: https://lore.kernel.org/r/20240126203208.2482573-1-peter@korsgaard.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Korsgaard 2024-01-26 21:32:08 +01:00 committed by Greg Kroah-Hartman
parent 2d2a334952
commit 43a029724d
3 changed files with 38 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

12
Documentation/ABI/testing/configfs-usb-gadget-ffs
View File

@ -4,6 +4,14 @@ KernelVersion: 3.13
Description: The purpose of this directory is to create and remove it.
A corresponding USB function instance is created/removed.
There are no attributes here.
All parameters are set through FunctionFS.
All attributes are read only:
============= ============================================
ready 1 if the function is ready to be used, E.G.
if userspace has written descriptors and
strings to ep0, so the gadget can be
enabled - 0 otherwise.
============= ============================================
All other parameters are set through FunctionFS.

8
Documentation/usb/gadget-testing.rst
View File

@ -206,6 +206,14 @@ the standard procedure for using FunctionFS (mount it, run the userspace
process which implements the function proper). The gadget should be enabled
by writing a suitable string to usb_gadget/<gadget>/UDC.
The FFS function provides just one attribute in its function directory:
ready
The attribute is read-only and signals if the function is ready (1) to be
used, E.G. if userspace has written descriptors and strings to ep0, so
the gadget can be enabled.
Testing the FFS function
------------------------

20
drivers/usb/gadget/function/f_fs.c
View File

@ -3445,6 +3445,25 @@ static inline struct f_fs_opts *to_ffs_opts(struct config_item *item)
func_inst.group);
}
static ssize_t f_fs_opts_ready_show(struct config_item *item, char *page)
{
struct f_fs_opts *opts = to_ffs_opts(item);
int ready;
ffs_dev_lock();
ready = opts->dev->desc_ready;
ffs_dev_unlock();
return sprintf(page, "%d\n", ready);
}
CONFIGFS_ATTR_RO(f_fs_opts_, ready);
static struct configfs_attribute *ffs_attrs[] = {
&f_fs_opts_attr_ready,
NULL,
};
static void ffs_attr_release(struct config_item *item)
{
struct f_fs_opts *opts = to_ffs_opts(item);
@ -3458,6 +3477,7 @@ static struct configfs_item_operations ffs_item_ops = {
static const struct config_item_type ffs_func_type = {
.ct_item_ops = &ffs_item_ops,
.ct_attrs = ffs_attrs,
.ct_owner = THIS_MODULE,
};