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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,
        Biju Das <biju.das.jz@bp.renesas.com>,
        Geert Uytterhoeven <geert+renesas@glider.be>,
        =?UTF-8?q?Uwe=20Kleine-K=C3=B6nig?= 
        <u.kleine-koenig@pengutronix.de>, Rob Herring <robh@kernel.org>,
        Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
        =?UTF-8?q?Ilpo=20J=C3=A4rvinen?= <ilpo.jarvinen@linux.intel.com>
Subject: [PATCH tty v1 60/74] serial: sh-sci: Use port lock wrappers
Date:   Thu, 14 Sep 2023 20:44:17 +0206
Message-Id: <20230914183831.587273-61-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/sh-sci.c | 68 ++++++++++++++++++-------------------
 1 file changed, 34 insertions(+), 34 deletions(-)

diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c
index a560b729fa3b..84ab434c94ba 100644
--- a/drivers/tty/serial/sh-sci.c
+++ b/drivers/tty/serial/sh-sci.c
@@ -1205,7 +1205,7 @@ static void sci_dma_tx_complete(void *arg)
 
 	dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	uart_xmit_advance(port, s->tx_dma_len);
 
@@ -1229,7 +1229,7 @@ static void sci_dma_tx_complete(void *arg)
 		}
 	}
 
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 }
 
 /* Locking: called with port lock held */
@@ -1320,7 +1320,7 @@ static void sci_dma_rx_complete(void *arg)
 	dev_dbg(port->dev, "%s(%d) active cookie %d\n", __func__, port->line,
 		s->active_rx);
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	active = sci_dma_rx_find_active(s);
 	if (active >= 0)
@@ -1347,20 +1347,20 @@ static void sci_dma_rx_complete(void *arg)
 
 	dma_async_issue_pending(chan);
 
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 	dev_dbg(port->dev, "%s: cookie %d #%d, new active cookie %d\n",
 		__func__, s->cookie_rx[active], active, s->active_rx);
 	return;
 
 fail:
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 	dev_warn(port->dev, "Failed submitting Rx DMA descriptor\n");
 	/* Switch to PIO */
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 	dmaengine_terminate_async(chan);
 	sci_dma_rx_chan_invalidate(s);
 	sci_dma_rx_reenable_irq(s);
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 }
 
 static void sci_dma_tx_release(struct sci_port *s)
@@ -1409,13 +1409,13 @@ static int sci_dma_rx_submit(struct sci_port *s, bool port_lock_held)
 fail:
 	/* Switch to PIO */
 	if (!port_lock_held)
-		spin_lock_irqsave(&port->lock, flags);
+		uart_port_lock_irqsave(port, &flags);
 	if (i)
 		dmaengine_terminate_async(chan);
 	sci_dma_rx_chan_invalidate(s);
 	sci_start_rx(port);
 	if (!port_lock_held)
-		spin_unlock_irqrestore(&port->lock, flags);
+		uart_port_unlock_irqrestore(port, flags);
 	return -EAGAIN;
 }
 
@@ -1437,14 +1437,14 @@ static void sci_dma_tx_work_fn(struct work_struct *work)
 	 * transmit till the end, and then the rest. Take the port lock to get a
 	 * consistent xmit buffer state.
 	 */
-	spin_lock_irq(&port->lock);
+	uart_port_lock_irq(port);
 	head = xmit->head;
 	tail = xmit->tail;
 	buf = s->tx_dma_addr + tail;
 	s->tx_dma_len = CIRC_CNT_TO_END(head, tail, UART_XMIT_SIZE);
 	if (!s->tx_dma_len) {
 		/* Transmit buffer has been flushed */
-		spin_unlock_irq(&port->lock);
+		uart_port_unlock_irq(port);
 		return;
 	}
 
@@ -1452,7 +1452,7 @@ static void sci_dma_tx_work_fn(struct work_struct *work)
 					   DMA_MEM_TO_DEV,
 					   DMA_PREP_INTERRUPT | DMA_CTRL_ACK);
 	if (!desc) {
-		spin_unlock_irq(&port->lock);
+		uart_port_unlock_irq(port);
 		dev_warn(port->dev, "Failed preparing Tx DMA descriptor\n");
 		goto switch_to_pio;
 	}
@@ -1464,12 +1464,12 @@ static void sci_dma_tx_work_fn(struct work_struct *work)
 	desc->callback_param = s;
 	s->cookie_tx = dmaengine_submit(desc);
 	if (dma_submit_error(s->cookie_tx)) {
-		spin_unlock_irq(&port->lock);
+		uart_port_unlock_irq(port);
 		dev_warn(port->dev, "Failed submitting Tx DMA descriptor\n");
 		goto switch_to_pio;
 	}
 
-	spin_unlock_irq(&port->lock);
+	uart_port_unlock_irq(port);
 	dev_dbg(port->dev, "%s: %p: %d...%d, cookie %d\n",
 		__func__, xmit->buf, tail, head, s->cookie_tx);
 
@@ -1477,10 +1477,10 @@ static void sci_dma_tx_work_fn(struct work_struct *work)
 	return;
 
 switch_to_pio:
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 	s->chan_tx = NULL;
 	sci_start_tx(port);
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 	return;
 }
 
@@ -1497,17 +1497,17 @@ static enum hrtimer_restart sci_dma_rx_timer_fn(struct hrtimer *t)
 
 	dev_dbg(port->dev, "DMA Rx timed out\n");
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	active = sci_dma_rx_find_active(s);
 	if (active < 0) {
-		spin_unlock_irqrestore(&port->lock, flags);
+		uart_port_unlock_irqrestore(port, flags);
 		return HRTIMER_NORESTART;
 	}
 
 	status = dmaengine_tx_status(s->chan_rx, s->active_rx, &state);
 	if (status == DMA_COMPLETE) {
-		spin_unlock_irqrestore(&port->lock, flags);
+		uart_port_unlock_irqrestore(port, flags);
 		dev_dbg(port->dev, "Cookie %d #%d has already completed\n",
 			s->active_rx, active);
 
@@ -1525,7 +1525,7 @@ static enum hrtimer_restart sci_dma_rx_timer_fn(struct hrtimer *t)
 	 */
 	status = dmaengine_tx_status(s->chan_rx, s->active_rx, &state);
 	if (status == DMA_COMPLETE) {
-		spin_unlock_irqrestore(&port->lock, flags);
+		uart_port_unlock_irqrestore(port, flags);
 		dev_dbg(port->dev, "Transaction complete after DMA engine was stopped");
 		return HRTIMER_NORESTART;
 	}
@@ -1546,7 +1546,7 @@ static enum hrtimer_restart sci_dma_rx_timer_fn(struct hrtimer *t)
 
 	sci_dma_rx_reenable_irq(s);
 
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 
 	return HRTIMER_NORESTART;
 }
@@ -1770,9 +1770,9 @@ static irqreturn_t sci_tx_interrupt(int irq, void *ptr)
 	struct uart_port *port = ptr;
 	unsigned long flags;
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 	sci_transmit_chars(port);
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 
 	return IRQ_HANDLED;
 }
@@ -1786,11 +1786,11 @@ static irqreturn_t sci_tx_end_interrupt(int irq, void *ptr)
 	if (port->type != PORT_SCI)
 		return sci_tx_interrupt(irq, ptr);
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 	ctrl = serial_port_in(port, SCSCR);
 	ctrl &= ~(SCSCR_TE | SCSCR_TEIE);
 	serial_port_out(port, SCSCR, ctrl);
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 
 	return IRQ_HANDLED;
 }
@@ -2187,7 +2187,7 @@ static void sci_break_ctl(struct uart_port *port, int break_state)
 		return;
 	}
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 	scsptr = serial_port_in(port, SCSPTR);
 	scscr = serial_port_in(port, SCSCR);
 
@@ -2201,7 +2201,7 @@ static void sci_break_ctl(struct uart_port *port, int break_state)
 
 	serial_port_out(port, SCSPTR, scsptr);
 	serial_port_out(port, SCSCR, scscr);
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 }
 
 static int sci_startup(struct uart_port *port)
@@ -2233,7 +2233,7 @@ static void sci_shutdown(struct uart_port *port)
 	s->autorts = false;
 	mctrl_gpio_disable_ms(to_sci_port(port)->gpios);
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 	sci_stop_rx(port);
 	sci_stop_tx(port);
 	/*
@@ -2243,7 +2243,7 @@ static void sci_shutdown(struct uart_port *port)
 	scr = serial_port_in(port, SCSCR);
 	serial_port_out(port, SCSCR, scr &
 			(SCSCR_CKE1 | SCSCR_CKE0 | s->hscif_tot));
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 
 #ifdef CONFIG_SERIAL_SH_SCI_DMA
 	if (s->chan_rx_saved) {
@@ -2545,7 +2545,7 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 		serial_port_out(port, SCCKS, sccks);
 	}
 
-	spin_lock_irqsave(&port->lock, flags);
+	uart_port_lock_irqsave(port, &flags);
 
 	sci_reset(port);
 
@@ -2667,7 +2667,7 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios,
 	if ((termios->c_cflag & CREAD) != 0)
 		sci_start_rx(port);
 
-	spin_unlock_irqrestore(&port->lock, flags);
+	uart_port_unlock_irqrestore(port, flags);
 
 	sci_port_disable(s);
 
@@ -3052,9 +3052,9 @@ static void serial_console_write(struct console *co, const char *s,
 	if (port->sysrq)
 		locked = 0;
 	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);
 
 	/* first save SCSCR then disable interrupts, keep clock source */
 	ctrl = serial_port_in(port, SCSCR);
@@ -3074,7 +3074,7 @@ static void serial_console_write(struct console *co, const char *s,
 	serial_port_out(port, SCSCR, ctrl);
 
 	if (locked)
-		spin_unlock_irqrestore(&port->lock, flags);
+		uart_port_unlock_irqrestore(port, flags);
 }
 
 static int serial_console_setup(struct console *co, char *options)
-- 
2.39.2