[tty,v1,29/74] serial: imx: Use port lock wrappers

Commit Message

John Ogness Sept. 14, 2023, 6:37 p.m. UTC

From: Thomas Gleixner <[e-mail]>

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 <[e-mail]>
---
 drivers/tty/serial/imx.c | 84 ++++++++++++++++++++--------------------
 1 file changed, 42 insertions(+), 42 deletions(-)

Comments

Uwe Kleine-König Sept. 15, 2023, 8:21 p.m. UTC | #1

On Thu, Sep 14, 2023 at 08:43:46PM +0206, John Ogness wrote:
> From: Thomas Gleixner <[e-mail]>
> 
> 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 <[e-mail]>

This lacks a Signed-off line by John.

Otherwise looks fine to me.

Best regards
Uwe

John Ogness Sept. 16, 2023, 7:45 p.m. UTC | #2

On 2023-09-15, Uwe Kleine-König <[e-mail]> wrote:
>> Converted with coccinelle. No functional change.
>> 
>> Signed-off-by: Thomas Gleixner <[e-mail]>
>
> This lacks a Signed-off line by John.

I really didn't have anything to do with the development of this
series. (I just did basic testing and the posting to LKML.) But I have
no problems adding my SoB if that is more appropriate.

John

Uwe Kleine-König Sept. 17, 2023, 12:11 p.m. UTC | #3

On Sat, Sep 16, 2023 at 09:51:40PM +0206, John Ogness wrote:
> On 2023-09-15, Uwe Kleine-König <[e-mail]> wrote:
> >> Converted with coccinelle. No functional change.
> >> 
> >> Signed-off-by: Thomas Gleixner <[e-mail]>
> >
> > This lacks a Signed-off line by John.
> 
> I really didn't have anything to do with the development of this
> series. (I just did basic testing and the posting to LKML.) But I have
> no problems adding my SoB if that is more appropriate.

If you sent it, you have enough to do with it, that your S-o-b is
required. See Documentation/process/submitting-patches.rst for the
details, which has for example:

	Notably, the last Signed-off-by: must always be that of the
	developer submitting the patch.

Best regards
Uwe

Patch

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 13cb78340709..0fb679cdb15e 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -575,7 +575,7 @@  static void imx_uart_dma_tx_callback(void *data)
 	unsigned long flags;
 	u32 ucr1;
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	uart_port_lock_irqsave(&sport->port, &flags);
 
 	dma_unmap_sg(sport->port.dev, sgl, sport->dma_tx_nents, DMA_TO_DEVICE);
 
@@ -600,7 +600,7 @@  static void imx_uart_dma_tx_callback(void *data)
 		imx_uart_writel(sport, ucr4, UCR4);
 	}
 
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	uart_port_unlock_irqrestore(&sport->port, flags);
 }
 
 /* called with port.lock taken and irqs off */
@@ -766,11 +766,11 @@  static irqreturn_t imx_uart_rtsint(int irq, void *dev_id)
 	struct imx_port *sport = dev_id;
 	irqreturn_t ret;
 
-	spin_lock(&sport->port.lock);
+	uart_port_lock(&sport->port);
 
 	ret = __imx_uart_rtsint(irq, dev_id);
 
-	spin_unlock(&sport->port.lock);
+	uart_port_unlock(&sport->port);
 
 	return ret;
 }
@@ -779,9 +779,9 @@  static irqreturn_t imx_uart_txint(int irq, void *dev_id)
 {
 	struct imx_port *sport = dev_id;
 
-	spin_lock(&sport->port.lock);
+	uart_port_lock(&sport->port);
 	imx_uart_transmit_buffer(sport);
-	spin_unlock(&sport->port.lock);
+	uart_port_unlock(&sport->port);
 	return IRQ_HANDLED;
 }
 
@@ -895,11 +895,11 @@  static irqreturn_t imx_uart_rxint(int irq, void *dev_id)
 	struct imx_port *sport = dev_id;
 	irqreturn_t ret;
 
-	spin_lock(&sport->port.lock);
+	uart_port_lock(&sport->port);
 
 	ret = __imx_uart_rxint(irq, dev_id);
 
-	spin_unlock(&sport->port.lock);
+	uart_port_unlock(&sport->port);
 
 	return ret;
 }
@@ -962,7 +962,7 @@  static irqreturn_t imx_uart_int(int irq, void *dev_id)
 	unsigned int usr1, usr2, ucr1, ucr2, ucr3, ucr4;
 	irqreturn_t ret = IRQ_NONE;
 
-	spin_lock(&sport->port.lock);
+	uart_port_lock(&sport->port);
 
 	usr1 = imx_uart_readl(sport, USR1);
 	usr2 = imx_uart_readl(sport, USR2);
@@ -1032,7 +1032,7 @@  static irqreturn_t imx_uart_int(int irq, void *dev_id)
 		ret = IRQ_HANDLED;
 	}
 
-	spin_unlock(&sport->port.lock);
+	uart_port_unlock(&sport->port);
 
 	return ret;
 }
@@ -1115,7 +1115,7 @@  static void imx_uart_break_ctl(struct uart_port *port, int break_state)
 	unsigned long flags;
 	u32 ucr1;
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	uart_port_lock_irqsave(&sport->port, &flags);
 
 	ucr1 = imx_uart_readl(sport, UCR1) & ~UCR1_SNDBRK;
 
@@ -1124,7 +1124,7 @@  static void imx_uart_break_ctl(struct uart_port *port, int break_state)
 
 	imx_uart_writel(sport, ucr1, UCR1);
 
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	uart_port_unlock_irqrestore(&sport->port, flags);
 }
 
 /*
@@ -1137,9 +1137,9 @@  static void imx_uart_timeout(struct timer_list *t)
 	unsigned long flags;
 
 	if (sport->port.state) {
-		spin_lock_irqsave(&sport->port.lock, flags);
+		uart_port_lock_irqsave(&sport->port, &flags);
 		imx_uart_mctrl_check(sport);
-		spin_unlock_irqrestore(&sport->port.lock, flags);
+		uart_port_unlock_irqrestore(&sport->port, flags);
 
 		mod_timer(&sport->timer, jiffies + MCTRL_TIMEOUT);
 	}
@@ -1169,9 +1169,9 @@  static void imx_uart_dma_rx_callback(void *data)
 	status = dmaengine_tx_status(chan, sport->rx_cookie, &state);
 
 	if (status == DMA_ERROR) {
-		spin_lock(&sport->port.lock);
+		uart_port_lock(&sport->port);
 		imx_uart_clear_rx_errors(sport);
-		spin_unlock(&sport->port.lock);
+		uart_port_unlock(&sport->port);
 		return;
 	}
 
@@ -1200,9 +1200,9 @@  static void imx_uart_dma_rx_callback(void *data)
 		r_bytes = rx_ring->head - rx_ring->tail;
 
 		/* If we received something, check for 0xff flood */
-		spin_lock(&sport->port.lock);
+		uart_port_lock(&sport->port);
 		imx_uart_check_flood(sport, imx_uart_readl(sport, USR2));
-		spin_unlock(&sport->port.lock);
+		uart_port_unlock(&sport->port);
 
 		if (!(sport->port.ignore_status_mask & URXD_DUMMY_READ)) {
 
@@ -1460,7 +1460,7 @@  static int imx_uart_startup(struct uart_port *port)
 	if (!uart_console(port) && imx_uart_dma_init(sport) == 0)
 		dma_is_inited = 1;
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	uart_port_lock_irqsave(&sport->port, &flags);
 
 	/* Reset fifo's and state machines */
 	imx_uart_soft_reset(sport);
@@ -1533,7 +1533,7 @@  static int imx_uart_startup(struct uart_port *port)
 
 	imx_uart_disable_loopback_rs485(sport);
 
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	uart_port_unlock_irqrestore(&sport->port, flags);
 
 	return 0;
 }
@@ -1558,21 +1558,21 @@  static void imx_uart_shutdown(struct uart_port *port)
 			sport->dma_is_rxing = 0;
 		}
 
-		spin_lock_irqsave(&sport->port.lock, flags);
+		uart_port_lock_irqsave(&sport->port, &flags);
 		imx_uart_stop_tx(port);
 		imx_uart_stop_rx(port);
 		imx_uart_disable_dma(sport);
-		spin_unlock_irqrestore(&sport->port.lock, flags);
+		uart_port_unlock_irqrestore(&sport->port, flags);
 		imx_uart_dma_exit(sport);
 	}
 
 	mctrl_gpio_disable_ms(sport->gpios);
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	uart_port_lock_irqsave(&sport->port, &flags);
 	ucr2 = imx_uart_readl(sport, UCR2);
 	ucr2 &= ~(UCR2_TXEN | UCR2_ATEN);
 	imx_uart_writel(sport, ucr2, UCR2);
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	uart_port_unlock_irqrestore(&sport->port, flags);
 
 	/*
 	 * Stop our timer.
@@ -1583,7 +1583,7 @@  static void imx_uart_shutdown(struct uart_port *port)
 	 * Disable all interrupts, port and break condition.
 	 */
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	uart_port_lock_irqsave(&sport->port, &flags);
 
 	ucr1 = imx_uart_readl(sport, UCR1);
 	ucr1 &= ~(UCR1_TRDYEN | UCR1_RRDYEN | UCR1_RTSDEN | UCR1_RXDMAEN |
@@ -1605,7 +1605,7 @@  static void imx_uart_shutdown(struct uart_port *port)
 	ucr4 &= ~UCR4_TCEN;
 	imx_uart_writel(sport, ucr4, UCR4);
 
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	uart_port_unlock_irqrestore(&sport->port, flags);
 
 	clk_disable_unprepare(sport->clk_per);
 	clk_disable_unprepare(sport->clk_ipg);
@@ -1668,7 +1668,7 @@  imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
 	baud = uart_get_baud_rate(port, termios, old, 50, port->uartclk / 16);
 	quot = uart_get_divisor(port, baud);
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	uart_port_lock_irqsave(&sport->port, &flags);
 
 	/*
 	 * Read current UCR2 and save it for future use, then clear all the bits
@@ -1796,7 +1796,7 @@  imx_uart_set_termios(struct uart_port *port, struct ktermios *termios,
 	if (UART_ENABLE_MS(&sport->port, termios->c_cflag))
 		imx_uart_enable_ms(&sport->port);
 
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	uart_port_unlock_irqrestore(&sport->port, flags);
 }
 
 static const char *imx_uart_type(struct uart_port *port)
@@ -1858,7 +1858,7 @@  static int imx_uart_poll_init(struct uart_port *port)
 
 	imx_uart_setup_ufcr(sport, TXTL_DEFAULT, RXTL_DEFAULT);
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	uart_port_lock_irqsave(&sport->port, &flags);
 
 	/*
 	 * Be careful about the order of enabling bits here. First enable the
@@ -1886,7 +1886,7 @@  static int imx_uart_poll_init(struct uart_port *port)
 	imx_uart_writel(sport, ucr1 | UCR1_RRDYEN, UCR1);
 	imx_uart_writel(sport, ucr2 | UCR2_ATEN, UCR2);
 
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	uart_port_unlock_irqrestore(&sport->port, flags);
 
 	return 0;
 }
@@ -2005,9 +2005,9 @@  imx_uart_console_write(struct console *co, const char *s, unsigned int count)
 	if (sport->port.sysrq)
 		locked = 0;
 	else if (oops_in_progress)
-		locked = spin_trylock_irqsave(&sport->port.lock, flags);
+		locked = uart_port_trylock_irqsave(&sport->port, &flags);
 	else
-		spin_lock_irqsave(&sport->port.lock, flags);
+		uart_port_lock_irqsave(&sport->port, &flags);
 
 	/*
 	 *	First, save UCR1/2/3 and then disable interrupts
@@ -2035,7 +2035,7 @@  imx_uart_console_write(struct console *co, const char *s, unsigned int count)
 	imx_uart_ucrs_restore(sport, &old_ucr);
 
 	if (locked)
-		spin_unlock_irqrestore(&sport->port.lock, flags);
+		uart_port_unlock_irqrestore(&sport->port, flags);
 }
 
 /*
@@ -2193,10 +2193,10 @@  static enum hrtimer_restart imx_trigger_start_tx(struct hrtimer *t)
 	struct imx_port *sport = container_of(t, struct imx_port, trigger_start_tx);
 	unsigned long flags;
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	uart_port_lock_irqsave(&sport->port, &flags);
 	if (sport->tx_state == WAIT_AFTER_RTS)
 		imx_uart_start_tx(&sport->port);
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	uart_port_unlock_irqrestore(&sport->port, flags);
 
 	return HRTIMER_NORESTART;
 }
@@ -2206,10 +2206,10 @@  static enum hrtimer_restart imx_trigger_stop_tx(struct hrtimer *t)
 	struct imx_port *sport = container_of(t, struct imx_port, trigger_stop_tx);
 	unsigned long flags;
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	uart_port_lock_irqsave(&sport->port, &flags);
 	if (sport->tx_state == WAIT_AFTER_SEND)
 		imx_uart_stop_tx(&sport->port);
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	uart_port_unlock_irqrestore(&sport->port, flags);
 
 	return HRTIMER_NORESTART;
 }
@@ -2482,9 +2482,9 @@  static void imx_uart_restore_context(struct imx_port *sport)
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&sport->port.lock, flags);
+	uart_port_lock_irqsave(&sport->port, &flags);
 	if (!sport->context_saved) {
-		spin_unlock_irqrestore(&sport->port.lock, flags);
+		uart_port_unlock_irqrestore(&sport->port, flags);
 		return;
 	}
 
@@ -2499,7 +2499,7 @@  static void imx_uart_restore_context(struct imx_port *sport)
 	imx_uart_writel(sport, sport->saved_reg[2], UCR3);
 	imx_uart_writel(sport, sport->saved_reg[3], UCR4);
 	sport->context_saved = false;
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	uart_port_unlock_irqrestore(&sport->port, flags);
 }
 
 static void imx_uart_save_context(struct imx_port *sport)
@@ -2507,7 +2507,7 @@  static void imx_uart_save_context(struct imx_port *sport)
 	unsigned long flags;
 
 	/* Save necessary regs */
-	spin_lock_irqsave(&sport->port.lock, flags);
+	uart_port_lock_irqsave(&sport->port, &flags);
 	sport->saved_reg[0] = imx_uart_readl(sport, UCR1);
 	sport->saved_reg[1] = imx_uart_readl(sport, UCR2);
 	sport->saved_reg[2] = imx_uart_readl(sport, UCR3);
@@ -2519,7 +2519,7 @@  static void imx_uart_save_context(struct imx_port *sport)
 	sport->saved_reg[8] = imx_uart_readl(sport, UBMR);
 	sport->saved_reg[9] = imx_uart_readl(sport, IMX21_UTS);
 	sport->context_saved = true;
-	spin_unlock_irqrestore(&sport->port.lock, flags);
+	uart_port_unlock_irqrestore(&sport->port, flags);
 }
 
 static void imx_uart_enable_wakeup(struct imx_port *sport, bool on)