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-li...@rere.qmqm.pl> --- v6: rebased on balbi/testing/next v5: no changes v4: initial revision, new in the patchset --- drivers/usb/gadget/legacy/serial.c | 49 +++++++++++++++++++++++++++++- 1 file changed, 48 insertions(+), 1 deletion(-) diff --git a/drivers/usb/gadget/legacy/serial.c b/drivers/usb/gadget/legacy/serial.c index de30d7628eef..da44f89f5e73 100644 --- a/drivers/usb/gadget/legacy/serial.c +++ b/drivers/usb/gadget/legacy/serial.c @@ -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); -- 2.20.1