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serial: stm32: fix wake-up flag handling

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[ Upstream commit 12761869f0 ]

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: 270e5a74fe ("serial: stm32: add wakeup mechanism")
Signed-off-by: Erwan Le Ray <erwan.leray@foss.st.com>
Link: https://lore.kernel.org/r/20210304162308.8984-7-erwan.leray@foss.st.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Erwan Le Ray 2021-03-04 17:23:01 +01:00 • committed by Greg Kroah-Hartman
commit 5eacd7fa40
1 changed files with 19 additions and 13 deletions
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32
drivers/tty/serial/stm32-usart.c
View file

@ -217,9 +217,6 @@ 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
@ -462,6 +459,7 @@ 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;
@ -472,9 +470,14 @@ 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);
@ -899,6 +902,12 @@ 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);
@ -1466,23 +1475,20 @@ 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);
}
}