add dts config

hc

2023-12-06 08f87f769b595151be1afeff53e144f543faa614

 kernel/drivers/usb/gadget/legacy/serial.c
..
..
@@ -97,6 +97,36 @@
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 module_param(n_ports, uint, 0);
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 MODULE_PARM_DESC(n_ports, "number of ports to create, default=1");
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+static bool enable = true;
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+
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+static int switch_gserial_enable(bool do_enable);
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+
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+static int enable_set(const char *s, const struct kernel_param *kp)
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+{
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+	bool do_enable;
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+	int ret;
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+
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+	if (!s)	/* called for no-arg enable == default */
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+		return 0;
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+
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+	ret = strtobool(s, &do_enable);
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+	if (ret || enable == do_enable)
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+		return ret;
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+
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+	ret = switch_gserial_enable(do_enable);
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+	if (!ret)
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+		enable = do_enable;
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+
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+	return ret;
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+}
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+
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+static const struct kernel_param_ops enable_ops = {
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+	.set = enable_set,
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+	.get = param_get_bool,
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+};
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+
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+module_param_cb(enable, &enable_ops, &enable, 0644);
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+
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 /*-------------------------------------------------------------------------*/
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 static struct usb_configuration serial_config_driver = {
..
..
@@ -240,6 +270,19 @@
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 	.unbind		= gs_unbind,
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 };
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+static int switch_gserial_enable(bool do_enable)
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+{
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+	if (!serial_config_driver.label)
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+		/* init() was not called, yet */
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+		return 0;
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+
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+	if (do_enable)
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+		return usb_composite_probe(&gserial_driver);
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+
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+	usb_composite_unregister(&gserial_driver);
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+	return 0;
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+}
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+
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 static int __init init(void)
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 {
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 	/* We *could* export two configs; that'd be much cleaner...
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@@ -266,12 +309,16 @@
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 	}
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 	strings_dev[STRING_DESCRIPTION_IDX].s = serial_config_driver.label;
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311
 
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+	if (!enable)
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+		return 0;
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+
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 	return usb_composite_probe(&gserial_driver);
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 }
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 module_init(init);
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 static void __exit cleanup(void)
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 {
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-	usb_composite_unregister(&gserial_driver);
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+	if (enable)
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+		usb_composite_unregister(&gserial_driver);
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 }
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 module_exit(cleanup);