usb: gadget: u_serial: allow more console gadget ports

Allow configuring more than one console using USB serial or ACM gadget.

By default, only first (ttyGS0) is a console, but this may be changed
using function's new "console" attribute.
Signed-off-by: Michał Mirosław <mirq-linux@rere.qmqm.pl>
Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com>

drivers/usb/gadget/function/f_acm.c

@@ -771,6 +771,24 @@ static struct configfs_item_operations acm_item_ops = {
 	.release                = acm_attr_release,
 };
 
+#ifdef CONFIG_U_SERIAL_CONSOLE
+
+static ssize_t f_acm_console_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	return gserial_set_console(to_f_serial_opts(item)->port_num,
+				   page, count);
+}
+
+static ssize_t f_acm_console_show(struct config_item *item, char *page)
+{
+	return gserial_get_console(to_f_serial_opts(item)->port_num, page);
+}
+
+CONFIGFS_ATTR(f_acm_, console);
+
+#endif /* CONFIG_U_SERIAL_CONSOLE */
+
 static ssize_t f_acm_port_num_show(struct config_item *item, char *page)
 {
 	return sprintf(page, "%u\n", to_f_serial_opts(item)->port_num);
@@ -779,6 +797,9 @@ static ssize_t f_acm_port_num_show(struct config_item *item, char *page)
 CONFIGFS_ATTR_RO(f_acm_, port_num);
 
 static struct configfs_attribute *acm_attrs[] = {
+#ifdef CONFIG_U_SERIAL_CONSOLE
+	&f_acm_attr_console,
+#endif
 	&f_acm_attr_port_num,
 	NULL,
 };

drivers/usb/gadget/function/f_serial.c

@@ -266,6 +266,24 @@ static struct configfs_item_operations serial_item_ops = {
 	.release	= serial_attr_release,
 };
 
+#ifdef CONFIG_U_SERIAL_CONSOLE
+
+static ssize_t f_serial_console_store(struct config_item *item,
+		const char *page, size_t count)
+{
+	return gserial_set_console(to_f_serial_opts(item)->port_num,
+				   page, count);
+}
+
+static ssize_t f_serial_console_show(struct config_item *item, char *page)
+{
+	return gserial_get_console(to_f_serial_opts(item)->port_num, page);
+}
+
+CONFIGFS_ATTR(f_serial_, console);
+
+#endif /* CONFIG_U_SERIAL_CONSOLE */
+
 static ssize_t f_serial_port_num_show(struct config_item *item, char *page)
 {
 	return sprintf(page, "%u\n", to_f_serial_opts(item)->port_num);
@@ -274,6 +292,9 @@ static ssize_t f_serial_port_num_show(struct config_item *item, char *page)
 CONFIGFS_ATTR_RO(f_serial_, port_num);
 
 static struct configfs_attribute *acm_attrs[] = {
+#ifdef CONFIG_U_SERIAL_CONSOLE
+	&f_serial_attr_console,
+#endif
 	&f_serial_attr_port_num,
 	NULL,
 };

drivers/usb/gadget/function/u_serial.c

@@ -1081,6 +1081,54 @@ static void gs_console_exit(struct gs_port *port)
 	port->console = NULL;
 }
 
+ssize_t gserial_set_console(unsigned char port_num, const char *page, size_t count)
+{
+	struct gs_port *port;
+	bool enable;
+	int ret;
+
+	ret = strtobool(page, &enable);
+	if (ret)
+		return ret;
+
+	mutex_lock(&ports[port_num].lock);
+	port = ports[port_num].port;
+
+	if (WARN_ON(port == NULL)) {
+		ret = -ENXIO;
+		goto out;
+	}
+
+	if (enable)
+		ret = gs_console_init(port);
+	else
+		gs_console_exit(port);
+out:
+	mutex_unlock(&ports[port_num].lock);
+
+	return ret < 0 ? ret : count;
+}
+EXPORT_SYMBOL_GPL(gserial_set_console);
+
+ssize_t gserial_get_console(unsigned char port_num, char *page)
+{
+	struct gs_port *port;
+	ssize_t ret;
+
+	mutex_lock(&ports[port_num].lock);
+	port = ports[port_num].port;
+
+	if (WARN_ON(port == NULL))
+		ret = -ENXIO;
+	else
+		ret = sprintf(page, "%u\n", !!port->console);
+
+	mutex_unlock(&ports[port_num].lock);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(gserial_get_console);
+
 #else
 
 static int gs_console_connect(struct gs_port *port)

drivers/usb/gadget/function/u_serial.h

@@ -58,6 +58,13 @@ int gserial_alloc_line_no_console(unsigned char *port_line);
 int gserial_alloc_line(unsigned char *port_line);
 void gserial_free_line(unsigned char port_line);
 
+#ifdef CONFIG_U_SERIAL_CONSOLE
+
+ssize_t gserial_set_console(unsigned char port_num, const char *page, size_t count);
+ssize_t gserial_get_console(unsigned char port_num, char *page);
+
+#endif /* CONFIG_U_SERIAL_CONSOLE */
+
 /* connect/disconnect is handled by individual functions */
 int gserial_connect(struct gserial *, u8 port_num);
 void gserial_disconnect(struct gserial *);