[PATCH printk v4 08/27] serial: core: Provide low-level functions to lock port

[John Ogness <john.ogness@linutronix.de>]

It will be necessary at times for the uart nbcon console
drivers to acquire the port lock directly (without the
additional nbcon functionality of the port lock wrappers).
These are special cases such as the implementation of the
device_lock()/device_unlock() callbacks or for internal
port lock wrapper synchronization.

Provide low-level variants __uart_port_lock_irqsave() and
__uart_port_unlock_irqrestore() for this purpose.

Signed-off-by: John Ogness <john.ogness@linutronix.de>
---
 include/linux/serial_core.h | 18 ++++++++++++++++++
 1 file changed, 18 insertions(+)

diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 55b1f3ba48ac..bb3324d49453 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -588,6 +588,24 @@ struct uart_port {
 	void			*private_data;		/* generic platform data pointer */
 };
 
+/*
+ * Only for console->device_lock()/_unlock() callbacks and internal
+ * port lock wrapper synchronization.
+ */
+static inline void __uart_port_lock_irqsave(struct uart_port *up, unsigned long *flags)
+{
+	spin_lock_irqsave(&up->lock, *flags);
+}
+
+/*
+ * Only for console->device_lock()/_unlock() callbacks and internal
+ * port lock wrapper synchronization.
+ */
+static inline void __uart_port_unlock_irqrestore(struct uart_port *up, unsigned long flags)
+{
+	spin_unlock_irqrestore(&up->lock, flags);
+}
+
 /**
  * uart_port_lock - Lock the UART port
  * @up:		Pointer to UART port structure
-- 
2.39.2