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author | 2022-09-11 11:02:03 +0200 | |
---|---|---|
committer | 2022-09-22 16:43:08 +0200 | |
commit | adafbbf6895eb0ce41a313c6ee68870ab9aa93cd (patch) | |
tree | fb7afaa57f1c6c53f832b26793a198792048689e /drivers/tty | |
parent | serial: ar933x: Deassert Transmit Enable on ->rs485_config() (diff) | |
download | linux-adafbbf6895eb0ce41a313c6ee68870ab9aa93cd.tar.gz linux-adafbbf6895eb0ce41a313c6ee68870ab9aa93cd.tar.bz2 linux-adafbbf6895eb0ce41a313c6ee68870ab9aa93cd.zip |
serial: stm32: Deassert Transmit Enable on ->rs485_config()
The STM32 USART can control RS-485 Transmit Enable in hardware. Since
commit 7df5081cbf5e ("serial: stm32: Add RS485 RTS GPIO control"),
it can alternatively be controlled in software. That was done to allow
RS-485 even if the RTS pin is unavailable because it's pinmuxed to a
different function.
However the commit neglected to deassert Transmit Enable upon invocation
of the ->rs485_config() callback. Fix it.
Avoid forward declarations by moving stm32_usart_tx_empty(),
stm32_usart_rs485_rts_enable() and stm32_usart_rs485_rts_disable()
further up in the driver.
Fixes: 7df5081cbf5e ("serial: stm32: Add RS485 RTS GPIO control")
Cc: stable@vger.kernel.org # v5.9+
Cc: Marek Vasut <marex@denx.de>
Reviewed-by: Ilpo Järvinen <ilpo.jarvinen@linux.intel.com>
Signed-off-by: Lukas Wunner <lukas@wunner.de>
Link: https://lore.kernel.org/r/6059eab35dba394468335ef640df8b0050fd9dbd.1662886616.git.lukas@wunner.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/tty')
-rw-r--r-- | drivers/tty/serial/stm32-usart.c | 100 |
1 files changed, 53 insertions, 47 deletions
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c index 0b18615b2ca4..c48f225eba86 100644 --- a/drivers/tty/serial/stm32-usart.c +++ b/drivers/tty/serial/stm32-usart.c @@ -131,6 +131,53 @@ static void stm32_usart_clr_bits(struct uart_port *port, u32 reg, u32 bits) writel_relaxed(val, port->membase + reg); } +static unsigned int stm32_usart_tx_empty(struct uart_port *port) +{ + struct stm32_port *stm32_port = to_stm32_port(port); + const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; + + if (readl_relaxed(port->membase + ofs->isr) & USART_SR_TC) + return TIOCSER_TEMT; + + return 0; +} + +static void stm32_usart_rs485_rts_enable(struct uart_port *port) +{ + struct stm32_port *stm32_port = to_stm32_port(port); + struct serial_rs485 *rs485conf = &port->rs485; + + if (stm32_port->hw_flow_control || + !(rs485conf->flags & SER_RS485_ENABLED)) + return; + + if (rs485conf->flags & SER_RS485_RTS_ON_SEND) { + mctrl_gpio_set(stm32_port->gpios, + stm32_port->port.mctrl | TIOCM_RTS); + } else { + mctrl_gpio_set(stm32_port->gpios, + stm32_port->port.mctrl & ~TIOCM_RTS); + } +} + +static void stm32_usart_rs485_rts_disable(struct uart_port *port) +{ + struct stm32_port *stm32_port = to_stm32_port(port); + struct serial_rs485 *rs485conf = &port->rs485; + + if (stm32_port->hw_flow_control || + !(rs485conf->flags & SER_RS485_ENABLED)) + return; + + if (rs485conf->flags & SER_RS485_RTS_ON_SEND) { + mctrl_gpio_set(stm32_port->gpios, + stm32_port->port.mctrl & ~TIOCM_RTS); + } else { + mctrl_gpio_set(stm32_port->gpios, + stm32_port->port.mctrl | TIOCM_RTS); + } +} + static void stm32_usart_config_reg_rs485(u32 *cr1, u32 *cr3, u32 delay_ADE, u32 delay_DDE, u32 baud) { @@ -214,6 +261,12 @@ static int stm32_usart_config_rs485(struct uart_port *port, struct ktermios *ter stm32_usart_set_bits(port, ofs->cr1, BIT(cfg->uart_enable_bit)); + /* Adjust RTS polarity in case it's driven in software */ + if (stm32_usart_tx_empty(port)) + stm32_usart_rs485_rts_disable(port); + else + stm32_usart_rs485_rts_enable(port); + return 0; } @@ -529,42 +582,6 @@ static void stm32_usart_tc_interrupt_disable(struct uart_port *port) stm32_usart_clr_bits(port, ofs->cr1, USART_CR1_TCIE); } -static void stm32_usart_rs485_rts_enable(struct uart_port *port) -{ - struct stm32_port *stm32_port = to_stm32_port(port); - struct serial_rs485 *rs485conf = &port->rs485; - - if (stm32_port->hw_flow_control || - !(rs485conf->flags & SER_RS485_ENABLED)) - return; - - if (rs485conf->flags & SER_RS485_RTS_ON_SEND) { - mctrl_gpio_set(stm32_port->gpios, - stm32_port->port.mctrl | TIOCM_RTS); - } else { - mctrl_gpio_set(stm32_port->gpios, - stm32_port->port.mctrl & ~TIOCM_RTS); - } -} - -static void stm32_usart_rs485_rts_disable(struct uart_port *port) -{ - struct stm32_port *stm32_port = to_stm32_port(port); - struct serial_rs485 *rs485conf = &port->rs485; - - if (stm32_port->hw_flow_control || - !(rs485conf->flags & SER_RS485_ENABLED)) - return; - - if (rs485conf->flags & SER_RS485_RTS_ON_SEND) { - mctrl_gpio_set(stm32_port->gpios, - stm32_port->port.mctrl & ~TIOCM_RTS); - } else { - mctrl_gpio_set(stm32_port->gpios, - stm32_port->port.mctrl | TIOCM_RTS); - } -} - static void stm32_usart_transmit_chars_pio(struct uart_port *port) { struct stm32_port *stm32_port = to_stm32_port(port); @@ -807,17 +824,6 @@ static irqreturn_t stm32_usart_threaded_interrupt(int irq, void *ptr) return IRQ_HANDLED; } -static unsigned int stm32_usart_tx_empty(struct uart_port *port) -{ - struct stm32_port *stm32_port = to_stm32_port(port); - const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs; - - if (readl_relaxed(port->membase + ofs->isr) & USART_SR_TC) - return TIOCSER_TEMT; - - return 0; -} - static void stm32_usart_set_mctrl(struct uart_port *port, unsigned int mctrl) { struct stm32_port *stm32_port = to_stm32_port(port); |