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[V5,0/3] Add rs485 support to uartps driver

Message ID 20231213130023.606486-1-manikanta.guntupalli@amd.com
Headers show
Series Add rs485 support to uartps driver | expand

Message

Manikanta Guntupalli Dec. 13, 2023, 1 p.m. UTC 
Add reference to rs485.yaml.
Add rs485 support to uartps driver.
---
Changes for V2:
Modify optional gpio name to xlnx,phy-ctrl-gpios.
Update commit description.
Add support for RTS, delay_rts_before_send and delay_rts_after_send in RS485 mode.

Changes for V3:
Modify optional gpio name to rts-gpios.
Update commit description.
Move cdns_uart_tx_empty function to avoid prototype statement.
Remove assignment of struct serial_rs485 to port->rs485 as
serial core performs that.
Switch to native RTS in non GPIO case.
Handle rs485 during stop tx.
Remove explicit calls to configure gpio direction and value,
as devm_gpiod_get_optional performs that by using GPIOD_OUT_LOW argument.
Update implementation to support configuration of GPIO/RTS value
based on user configuration of SER_RS485_RTS_ON_SEND and
SER_RS485_RTS_AFTER_SEND. Move implementation to start_tx from handle_tx.

Changes for V4:
Update rts-gpios description.
Create separate patch for cdns_uart_tx_empty relocation.
Call cdns_rs485_rx_setup() before uart_add_one_port() in probe.
Update gpio descriptor name to gpiod_rts.
Instead of cdns_rs485_config_gpio_rts_high() and
cdns_rs485_config_gpio_rts_low() functions for RTS/GPIO value
configuration implement cdns_rts_gpio_enable().
Disable auto rts and call cdns_uart_stop_tx() from cdns_rs485_config.
Use timer instead of mdelay for delay_rts_before_send and delay_rts_after_send.
Update cdns_uart_set_mctrl to support GPIO/RTS.

Changes for V5:
Remove rts-gpios description.
Update commit message and description.

Manikanta Guntupalli (3):
  dt-bindings: Add reference to rs485.yaml
  tty: serial: uartps: Relocate cdns_uart_tx_empty to facilitate rs485
  tty: serial: uartps: Add rs485 support to uartps driver

 .../devicetree/bindings/serial/cdns,uart.yaml |   1 +
 drivers/tty/serial/xilinx_uartps.c            | 244 ++++++++++++++++--
 2 files changed, 221 insertions(+), 24 deletions(-)

Comments

Lino Sanfilippo Dec. 14, 2023, 9 a.m. UTC | #1 
Hi,

On 13.12.23 14:00, Manikanta Guntupalli wrote:

>
> +/**
> + * cdns_rs485_rx_callback - Timer rx callback handler for rs485.
> + * @t: Handle to the timer list structure
> + */
> +static void cdns_rs485_rx_callback(struct timer_list *t)
> +{
> +	struct cdns_uart *cdns_uart = from_timer(cdns_uart, t, timer);
> +
> +	/*
> +	 * Default Rx should be setup, because Rx signaling path
> +	 * need to enable to receive data.
> +	 */
> +	cdns_rs485_rx_setup(cdns_uart);
> +}
> +
> +/**
> + * cdns_rs485_tx_callback - Timer tx callback handler for rs485.
> + * @t: Handle to the timer list structure
> + */
> +static void cdns_rs485_tx_callback(struct timer_list *t)
> +{
> +	struct cdns_uart *cdns_uart = from_timer(cdns_uart, t, timer);
> +
> +	cdns_uart_handle_tx(cdns_uart->port);

This is called without holding the port lock now. Are you sure the lock is not
needed? AFAIK the port lock is needed at least for accessing the circular
buffer.

> +
> +	/* Enable the TX Empty interrupt */
> +	writel(CDNS_UART_IXR_TXEMPTY, cdns_uart->port->membase + CDNS_UART_IER);
> +
> +	if (uart_circ_empty(&cdns_uart->port->state->xmit) ||
> +	    uart_tx_stopped(cdns_uart->port)) {
> +		timer_setup(&cdns_uart->timer, cdns_rs485_rx_callback, 0);
> +		mod_timer(&cdns_uart->timer, jiffies +
> +			  msecs_to_jiffies(cdns_uart->port->rs485.delay_rts_after_send));
> +	}
> +}

Regards,
Lino