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https://github.com/OpenVoiceOS/OpenVoiceOS
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132 lines
4.2 KiB
Diff
132 lines
4.2 KiB
Diff
From 681f56a112fc24a97bfdffcef7655e5bf9ffb6e8 Mon Sep 17 00:00:00 2001
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From: Thomas Gleixner <tglx@linutronix.de>
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Date: Thu, 14 Sep 2023 20:43:18 +0206
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Subject: [PATCH 028/195] serial: core: Provide port lock wrappers
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MIME-Version: 1.0
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Content-Type: text/plain; charset=UTF-8
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Content-Transfer-Encoding: 8bit
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When a serial port is used for kernel console output, then all
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modifications to the UART registers which are done from other contexts,
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e.g. getty, termios, are interference points for the kernel console.
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So far this has been ignored and the printk output is based on the
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principle of hope. The rework of the console infrastructure which aims to
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support threaded and atomic consoles, requires to mark sections which
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modify the UART registers as unsafe. This allows the atomic write function
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to make informed decisions and eventually to restore operational state. It
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also allows to prevent the regular UART code from modifying UART registers
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while printk output is in progress.
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All modifications of UART registers are guarded by the UART port lock,
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which provides an obvious synchronization point with the console
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infrastructure.
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Provide wrapper functions for spin_[un]lock*(port->lock) invocations so
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that the console mechanics can be applied later on at a single place and
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does not require to copy the same logic all over the drivers.
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Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
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Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
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Signed-off-by: John Ogness <john.ogness@linutronix.de>
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Link: https://lore.kernel.org/r/20230914183831.587273-2-john.ogness@linutronix.de
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Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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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 | 79 +++++++++++++++++++++++++++++++++++++
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1 file changed, 79 insertions(+)
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diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
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index bb6f073bc159..f1d5c0d1568c 100644
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--- a/include/linux/serial_core.h
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+++ b/include/linux/serial_core.h
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@@ -588,6 +588,85 @@ struct uart_port {
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void *private_data; /* generic platform data pointer */
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};
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+/**
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+ * uart_port_lock - Lock the UART port
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+ * @up: Pointer to UART port structure
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+ */
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+static inline void uart_port_lock(struct uart_port *up)
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+{
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+ spin_lock(&up->lock);
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+}
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+
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+/**
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+ * uart_port_lock_irq - Lock the UART port and disable interrupts
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+ * @up: Pointer to UART port structure
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+ */
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+static inline void uart_port_lock_irq(struct uart_port *up)
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+{
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+ spin_lock_irq(&up->lock);
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+}
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+
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+/**
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+ * uart_port_lock_irqsave - Lock the UART port, save and disable interrupts
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+ * @up: Pointer to UART port structure
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+ * @flags: Pointer to interrupt flags storage
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+ */
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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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+/**
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+ * uart_port_trylock - Try to lock the UART port
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+ * @up: Pointer to UART port structure
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+ *
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+ * Returns: True if lock was acquired, false otherwise
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+ */
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+static inline bool uart_port_trylock(struct uart_port *up)
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+{
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+ return spin_trylock(&up->lock);
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+}
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+
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+/**
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+ * uart_port_trylock_irqsave - Try to lock the UART port, save and disable interrupts
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+ * @up: Pointer to UART port structure
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+ * @flags: Pointer to interrupt flags storage
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+ *
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+ * Returns: True if lock was acquired, false otherwise
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+ */
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+static inline bool uart_port_trylock_irqsave(struct uart_port *up, unsigned long *flags)
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+{
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+ return spin_trylock_irqsave(&up->lock, *flags);
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+}
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+
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+/**
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+ * uart_port_unlock - Unlock the UART port
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+ * @up: Pointer to UART port structure
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+ */
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+static inline void uart_port_unlock(struct uart_port *up)
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+{
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+ spin_unlock(&up->lock);
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+}
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+
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+/**
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+ * uart_port_unlock_irq - Unlock the UART port and re-enable interrupts
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+ * @up: Pointer to UART port structure
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+ */
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+static inline void uart_port_unlock_irq(struct uart_port *up)
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+{
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+ spin_unlock_irq(&up->lock);
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+}
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+
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+/**
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+ * uart_port_lock_irqrestore - Unlock the UART port, restore interrupts
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+ * @up: Pointer to UART port structure
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+ * @flags: The saved interrupt flags for restore
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+ */
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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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--
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2.43.0
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