43 lines
1.6 KiB
Diff
43 lines
1.6 KiB
Diff
From: John Ogness <john.ogness@linutronix.de>
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Date: Mon, 11 Dec 2023 09:19:18 +0000
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Subject: [PATCH 130/134] serial: core: Provide low-level functions to port
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lock
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Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz
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The nbcon console's driver_enter() and driver_exit() callbacks need
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to lock the port lock in order to synchronize against other hardware
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activity (such as adjusting baud rates). However, they cannot use
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the uart_port_lock() wrappers because the printk subsystem will
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perform nbcon locking after calling the driver_enter() callback.
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Provide low-level variants __uart_port_lock_irqsave() and
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__uart_port_unlock_irqrestore() for this purpose. These are only
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to be used by the driver_enter()/driver_exit() callbacks.
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Signed-off-by: John Ogness <john.ogness@linutronix.de>
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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include/linux/serial_core.h | 12 ++++++++++++
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1 file changed, 12 insertions(+)
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--- a/include/linux/serial_core.h
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+++ b/include/linux/serial_core.h
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@@ -681,6 +681,18 @@ static inline void uart_port_unlock_irqr
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spin_unlock_irqrestore(&up->lock, flags);
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}
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+/* Only for use in the console->driver_enter() callback. */
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+static inline void __uart_port_lock_irqsave(struct uart_port *up, unsigned long *flags)
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+{
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+ spin_lock_irqsave(&up->lock, *flags);
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+}
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+
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+/* Only for use in the console->driver_exit() callback. */
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+static inline void __uart_port_unlock_irqrestore(struct uart_port *up, unsigned long flags)
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+{
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+ spin_unlock_irqrestore(&up->lock, flags);
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+}
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+
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static inline int serial_port_in(struct uart_port *up, int offset)
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{
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return up->serial_in(up, offset);
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