From: Thomas Gleixner <tglx@linutronix.de>
Date: Thu, 14 Sep 2023 20:44:20 +0206
Subject: [PATCH 063/134] serial: st-asc: Use port lock wrappers
Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/6.6/older/patches-6.6.7-rt18.tar.xz

When a serial port is used for kernel console output, then all
modifications to the UART registers which are done from other contexts,
e.g. getty, termios, are interference points for the kernel console.

So far this has been ignored and the printk output is based on the
principle of hope. The rework of the console infrastructure which aims to
support threaded and atomic consoles, requires to mark sections which
modify the UART registers as unsafe. This allows the atomic write function
to make informed decisions and eventually to restore operational state. It
also allows to prevent the regular UART code from modifying UART registers
while printk output is in progress.

All modifications of UART registers are guarded by the UART port lock,
which provides an obvious synchronization point with the console
infrastructure.

To avoid adding this functionality to all UART drivers, wrap the
spin_[un]lock*() invocations for uart_port::lock into helper functions
which just contain the spin_[un]lock*() invocations for now. In a
subsequent step these helpers will gain the console synchronization
mechanisms.

Converted with coccinelle. No functional change.

Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Link: https://lore.kernel.org/r/20230914183831.587273-64-john.ogness@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
 drivers/tty/serial/st-asc.c |   18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

--- a/drivers/tty/serial/st-asc.c
+++ b/drivers/tty/serial/st-asc.c
@@ -319,7 +319,7 @@ static irqreturn_t asc_interrupt(int irq
 	struct uart_port *port = ptr;
 	u32 status;
 
-	spin_lock(&port->lock);
+	uart_port_lock(port);
 
 	status = asc_in(port, ASC_STA);
 
@@ -334,7 +334,7 @@ static irqreturn_t asc_interrupt(int irq
 		asc_transmit_chars(port);
 	}
 
-	spin_unlock(&port->lock);
+	uart_port_unlock(port);
 
 	return IRQ_HANDLED;
 }
@@ -452,10 +452,10 @@ static void asc_pm(struct uart_port *por
 		 * we can come to turning it off. Note this is not called with
 		 * the port spinlock held.
 		 */
-		spin_lock_irqsave(&port->lock, flags);
+		uart_port_lock_irqsave(port, &flags);
 		ctl = asc_in(port, ASC_CTL) & ~ASC_CTL_RUN;
 		asc_out(port, ASC_CTL, ctl);
-		spin_unlock_irqrestore(&port->lock, flags);
+		uart_port_unlock_irqrestore(port, flags);
 		clk_disable_unprepare(ascport->clk);
 		break;
 	}
@@ -480,7 +480,7 @@ static void asc_set_termios(struct uart_
 	baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk/16);
 	cflag = termios->c_cflag;
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	/* read control register */
 	ctrl_val = asc_in(port, ASC_CTL);
@@ -594,7 +594,7 @@ static void asc_set_termios(struct uart_
 	/* write final value and enable port */
 	asc_out(port, ASC_CTL, (ctrl_val | ASC_CTL_RUN));
 
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 }
 
 static const char *asc_type(struct uart_port *port)
@@ -849,9 +849,9 @@ static void asc_console_write(struct con
 	if (port->sysrq)
 		locked = 0; /* asc_interrupt has already claimed the lock */
 	else if (oops_in_progress)
-		locked = spin_trylock_irqsave(&port->lock, flags);
+		locked = uart_port_trylock_irqsave(port, &flags);
 	else
-		spin_lock_irqsave(&port->lock, flags);
+		uart_port_lock_irqsave(port, &flags);
 
 	/*
 	 * Disable interrupts so we don't get the IRQ line bouncing
@@ -869,7 +869,7 @@ static void asc_console_write(struct con
 	asc_out(port, ASC_INTEN, intenable);
 
 	if (locked)
-		spin_unlock_irqrestore(&port->lock, flags);
+		uart_port_unlock_irqrestore(port, flags);
 }
 
 static int asc_console_setup(struct console *co, char *options)
