Commit 12761869 authored by Erwan Le Ray's avatar Erwan Le Ray Committed by Greg Kroah-Hartman
Browse files

serial: stm32: fix wake-up flag handling 



This patch fixes several issue with wake-up handling:
- the WUF irq is handled several times at wake-up
- the USART is disabled / enabled at suspend to set wake-up flag.
It can cause glitches during RX.

This patch fix those issues:
- clear wake-up flag and disable wake-up irq in WUF irq handling
- enable wake-up from low power on start bit detection at port
configuration
- Unmask the wake-up flag irq at suspend and mask it at resume

In addition, pm_wakeup_event handling is moved from receice_chars to WUF
irq handling.

Fixes: 270e5a74 ("serial: stm32: add wakeup mechanism")
Signed-off-by: default avatarErwan Le Ray <erwan.leray@foss.st.com>
Link: https://lore.kernel.org/r/20210304162308.8984-7-erwan.leray@foss.st.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent ad767681

drivers/tty/serial/stm32-usart.c

+19 −13
Original line number Diff line number Diff line
@@ -218,9 +218,6 @@ static void stm32_usart_receive_chars(struct uart_port *port, bool threaded) 
	u32 sr;

	char flag;



	if (irqd_is_wakeup_set(irq_get_irq_data(port->irq)))

		pm_wakeup_event(tport->tty->dev, 0);



	if (threaded)

		spin_lock_irqsave(&port->lock, flags);

	else
@@ -463,6 +460,7 @@ static void stm32_usart_transmit_chars(struct uart_port *port) 
static irqreturn_t stm32_usart_interrupt(int irq, void *ptr)

{

	struct uart_port *port = ptr;

	struct tty_port *tport = &port->state->port;

	struct stm32_port *stm32_port = to_stm32_port(port);

	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;

	u32 sr;
@@ -473,9 +471,14 @@ static irqreturn_t stm32_usart_interrupt(int irq, void *ptr) 
		writel_relaxed(USART_ICR_RTOCF,

			       port->membase + ofs->icr);



	if ((sr & USART_SR_WUF) && ofs->icr != UNDEF_REG)

	if ((sr & USART_SR_WUF) && ofs->icr != UNDEF_REG) {

		/* Clear wake up flag and disable wake up interrupt */

		writel_relaxed(USART_ICR_WUCF,

			       port->membase + ofs->icr);

		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_WUFIE);

		if (irqd_is_wakeup_set(irq_get_irq_data(port->irq)))

			pm_wakeup_event(tport->tty->dev, 0);

	}



	if ((sr & USART_SR_RXNE) && !(stm32_port->rx_ch))

		stm32_usart_receive_chars(port, false);
@@ -901,6 +904,12 @@ static void stm32_usart_set_termios(struct uart_port *port, 
		cr1 &= ~(USART_CR1_DEDT_MASK | USART_CR1_DEAT_MASK);

	}



	/* Configure wake up from low power on start bit detection */

	if (stm32_port->wakeirq > 0) {

		cr3 &= ~USART_CR3_WUS_MASK;

		cr3 |= USART_CR3_WUS_START_BIT;

	}



	writel_relaxed(cr3, port->membase + ofs->cr3);

	writel_relaxed(cr2, port->membase + ofs->cr2);

	writel_relaxed(cr1, port->membase + ofs->cr1);
@@ -1476,23 +1485,20 @@ static void __maybe_unused stm32_usart_serial_en_wakeup(struct uart_port *port, 
{

	struct stm32_port *stm32_port = to_stm32_port(port);

	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;

	const struct stm32_usart_config *cfg = &stm32_port->info->cfg;

	u32 val;



	if (stm32_port->wakeirq <= 0)

		return;



	/*

	 * Enable low-power wake-up and wake-up irq if argument is set to

	 * "enable", disable low-power wake-up and wake-up irq otherwise

	 */

	if (enable) {

		stm32_usart_clr_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));

		stm32_usart_set_bits(port, ofs->cr1, USART_CR1_UESM);

		val = readl_relaxed(port->membase + ofs->cr3);

		val &= ~USART_CR3_WUS_MASK;

		/* Enable Wake up interrupt from low power on start bit */

		val |= USART_CR3_WUS_START_BIT | USART_CR3_WUFIE;

		writel_relaxed(val, port->membase + ofs->cr3);

		stm32_usart_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit));

		stm32_usart_set_bits(port, ofs->cr3, USART_CR3_WUFIE);

	} else {

		stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_UESM);

		stm32_usart_clr_bits(port, ofs->cr3, USART_CR3_WUFIE);

	}

}