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usb: gadget: legacy/serial: allow dynamic removal

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Legacy serial USB gadget is still useful as an early console,
before userspace is up. Later it could be replaced with proper
configfs-configured composite gadget - that use case is enabled
by this patch.

Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>
This commit is contained in:
Michał Mirosław 2019-08-10 10:42:52 +02:00 committed by Felipe Balbi
parent d7cb8fb7aa
commit bd25a14edb
1 changed files with 48 additions and 1 deletions
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49
drivers/usb/gadget/legacy/serial.c
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@ -97,6 +97,36 @@ static unsigned n_ports = 1;
module_param(n_ports, uint, 0);
MODULE_PARM_DESC(n_ports, "number of ports to create, default=1");
static bool enable = true;
static int switch_gserial_enable(bool do_enable);
static int enable_set(const char *s, const struct kernel_param *kp)
{
bool do_enable;
int ret;
if (!s) /* called for no-arg enable == default */
return 0;
ret = strtobool(s, &do_enable);
if (ret || enable == do_enable)
return ret;
ret = switch_gserial_enable(do_enable);
if (!ret)
enable = do_enable;
return ret;
}
static const struct kernel_param_ops enable_ops = {
.set = enable_set,
.get = param_get_bool,
};
module_param_cb(enable, &enable_ops, &enable, 0644);
/*-------------------------------------------------------------------------*/
static struct usb_configuration serial_config_driver = {
@ -240,6 +270,19 @@ static struct usb_composite_driver gserial_driver = {
.unbind = gs_unbind,
};
static int switch_gserial_enable(bool do_enable)
{
if (!serial_config_driver.label)
/* init() was not called, yet */
return 0;
if (do_enable)
return usb_composite_probe(&gserial_driver);
usb_composite_unregister(&gserial_driver);
return 0;
}
static int __init init(void)
{
/* We *could* export two configs; that'd be much cleaner...
@ -266,12 +309,16 @@ static int __init init(void)
}
strings_dev[STRING_DESCRIPTION_IDX].s = serial_config_driver.label;
if (!enable)
return 0;
return usb_composite_probe(&gserial_driver);
}
module_init(init);
static void __exit cleanup(void)
{
usb_composite_unregister(&gserial_driver);
if (enable)
usb_composite_unregister(&gserial_driver);
}
module_exit(cleanup);