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From:   John Ogness <john.ogness@linutronix.de>
To:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc:     Jiri Slaby <jirislaby@kernel.org>, linux-serial@vger.kernel.org,
        Petr Mladek <pmladek@suse.com>,
        Thomas Gleixner <tglx@linutronix.de>,
        linux-kernel@vger.kernel.org,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        Alim Akhtar <alim.akhtar@samsung.com>,
        linux-arm-kernel@lists.infradead.org,
        linux-samsung-soc@vger.kernel.org
Subject: [PATCH tty v1 53/74] serial: samsung_tty: Use port lock wrappers
Date:   Thu, 14 Sep 2023 20:44:10 +0206
Message-Id: <20230914183831.587273-54-john.ogness@linutronix.de>
In-Reply-To: <20230914183831.587273-1-john.ogness@linutronix.de>
References: <20230914183831.587273-1-john.ogness@linutronix.de>
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From: Thomas Gleixner <tglx@linutronix.de>

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>
---
 drivers/tty/serial/samsung_tty.c | 50 ++++++++++++++++----------------
 1 file changed, 25 insertions(+), 25 deletions(-)

diff --git a/drivers/tty/serial/samsung_tty.c b/drivers/tty/serial/samsung_tty.c
index 07fb8a9dac63..ee51a0368a55 100644
--- a/drivers/tty/serial/samsung_tty.c
+++ b/drivers/tty/serial/samsung_tty.c
@@ -248,7 +248,7 @@ static void s3c24xx_serial_rx_enable(struct uart_port *port)
 	unsigned int ucon, ufcon;
 	int count = 10000;
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	while (--count && !s3c24xx_serial_txempty_nofifo(port))
 		udelay(100);
@@ -262,7 +262,7 @@ static void s3c24xx_serial_rx_enable(struct uart_port *port)
 	wr_regl(port, S3C2410_UCON, ucon);
 
 	ourport->rx_enabled = 1;
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 }
 
 static void s3c24xx_serial_rx_disable(struct uart_port *port)
@@ -271,14 +271,14 @@ static void s3c24xx_serial_rx_disable(struct uart_port *port)
 	unsigned long flags;
 	unsigned int ucon;
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	ucon = rd_regl(port, S3C2410_UCON);
 	ucon &= ~S3C2410_UCON_RXIRQMODE;
 	wr_regl(port, S3C2410_UCON, ucon);
 
 	ourport->rx_enabled = 0;
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 }
 
 static void s3c24xx_serial_stop_tx(struct uart_port *port)
@@ -344,7 +344,7 @@ static void s3c24xx_serial_tx_dma_complete(void *args)
 				dma->tx_transfer_addr, dma->tx_size,
 				DMA_TO_DEVICE);
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	uart_xmit_advance(port, count);
 	ourport->tx_in_progress = 0;
@@ -353,7 +353,7 @@ static void s3c24xx_serial_tx_dma_complete(void *args)
 		uart_write_wakeup(port);
 
 	s3c24xx_serial_start_next_tx(ourport);
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 }
 
 static void enable_tx_dma(struct s3c24xx_uart_port *ourport)
@@ -619,7 +619,7 @@ static void s3c24xx_serial_rx_dma_complete(void *args)
 	received  = dma->rx_bytes_requested - state.residue;
 	async_tx_ack(dma->rx_desc);
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	if (received)
 		s3c24xx_uart_copy_rx_to_tty(ourport, t, received);
@@ -631,7 +631,7 @@ static void s3c24xx_serial_rx_dma_complete(void *args)
 
 	s3c64xx_start_rx_dma(ourport);
 
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 }
 
 static void s3c64xx_start_rx_dma(struct s3c24xx_uart_port *ourport)
@@ -722,7 +722,7 @@ static irqreturn_t s3c24xx_serial_rx_chars_dma(void *dev_id)
 	utrstat = rd_regl(port, S3C2410_UTRSTAT);
 	rd_regl(port, S3C2410_UFSTAT);
 
-	spin_lock(&port->lock);
+	uart_port_lock(port);
 
 	if (!(utrstat & S3C2410_UTRSTAT_TIMEOUT)) {
 		s3c64xx_start_rx_dma(ourport);
@@ -751,7 +751,7 @@ static irqreturn_t s3c24xx_serial_rx_chars_dma(void *dev_id)
 	wr_regl(port, S3C2410_UTRSTAT, S3C2410_UTRSTAT_TIMEOUT);
 
 finish:
-	spin_unlock(&port->lock);
+	uart_port_unlock(port);
 
 	return IRQ_HANDLED;
 }
@@ -849,9 +849,9 @@ static irqreturn_t s3c24xx_serial_rx_chars_pio(void *dev_id)
 	struct s3c24xx_uart_port *ourport = dev_id;
 	struct uart_port *port = &ourport->port;
 
-	spin_lock(&port->lock);
+	uart_port_lock(port);
 	s3c24xx_serial_rx_drain_fifo(ourport);
-	spin_unlock(&port->lock);
+	uart_port_unlock(port);
 
 	return IRQ_HANDLED;
 }
@@ -932,11 +932,11 @@ static irqreturn_t s3c24xx_serial_tx_irq(int irq, void *id)
 	struct s3c24xx_uart_port *ourport = id;
 	struct uart_port *port = &ourport->port;
 
-	spin_lock(&port->lock);
+	uart_port_lock(port);
 
 	s3c24xx_serial_tx_chars(ourport);
 
-	spin_unlock(&port->lock);
+	uart_port_unlock(port);
 	return IRQ_HANDLED;
 }
 
@@ -1033,7 +1033,7 @@ static void s3c24xx_serial_break_ctl(struct uart_port *port, int break_state)
 	unsigned long flags;
 	unsigned int ucon;
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	ucon = rd_regl(port, S3C2410_UCON);
 
@@ -1044,7 +1044,7 @@ static void s3c24xx_serial_break_ctl(struct uart_port *port, int break_state)
 
 	wr_regl(port, S3C2410_UCON, ucon);
 
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 }
 
 static int s3c24xx_serial_request_dma(struct s3c24xx_uart_port *p)
@@ -1303,7 +1303,7 @@ static int s3c64xx_serial_startup(struct uart_port *port)
 	ourport->rx_enabled = 1;
 	ourport->tx_enabled = 0;
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	ufcon = rd_regl(port, S3C2410_UFCON);
 	ufcon |= S3C2410_UFCON_RESETRX | S5PV210_UFCON_RXTRIG8;
@@ -1313,7 +1313,7 @@ static int s3c64xx_serial_startup(struct uart_port *port)
 
 	enable_rx_pio(ourport);
 
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 
 	/* Enable Rx Interrupt */
 	s3c24xx_clear_bit(port, S3C64XX_UINTM_RXD, S3C64XX_UINTM);
@@ -1341,7 +1341,7 @@ static int apple_s5l_serial_startup(struct uart_port *port)
 	ourport->rx_enabled = 1;
 	ourport->tx_enabled = 0;
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	ufcon = rd_regl(port, S3C2410_UFCON);
 	ufcon |= S3C2410_UFCON_RESETRX | S5PV210_UFCON_RXTRIG8;
@@ -1351,7 +1351,7 @@ static int apple_s5l_serial_startup(struct uart_port *port)
 
 	enable_rx_pio(ourport);
 
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 
 	/* Enable Rx Interrupt */
 	s3c24xx_set_bit(port, APPLE_S5L_UCON_RXTHRESH_ENA, S3C2410_UCON);
@@ -1626,7 +1626,7 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
 		ulcon |= S3C2410_LCON_PNONE;
 	}
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	dev_dbg(port->dev,
 		"setting ulcon to %08x, brddiv to %d, udivslot %08x\n",
@@ -1684,7 +1684,7 @@ static void s3c24xx_serial_set_termios(struct uart_port *port,
 	if ((termios->c_cflag & CREAD) == 0)
 		port->ignore_status_mask |= RXSTAT_DUMMY_READ;
 
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 }
 
 static const char *s3c24xx_serial_type(struct uart_port *port)
@@ -2376,14 +2376,14 @@ s3c24xx_serial_console_write(struct console *co, const char *s,
 	if (cons_uart->sysrq)
 		locked = false;
 	else if (oops_in_progress)
-		locked = spin_trylock_irqsave(&cons_uart->lock, flags);
+		locked = uart_port_trylock_irqsave(cons_uart, &flags);
 	else
-		spin_lock_irqsave(&cons_uart->lock, flags);
+		uart_port_lock_irqsave(cons_uart, &flags);
 
 	uart_console_write(cons_uart, s, count, s3c24xx_serial_console_putchar);
 
 	if (locked)
-		spin_unlock_irqrestore(&cons_uart->lock, flags);
+		uart_port_unlock_irqrestore(cons_uart, flags);
 }
 
 /* Shouldn't be __init, as it can be instantiated from other module */
-- 
2.39.2