Commit 5602cf99 authored by Gabriel Somlo's avatar Gabriel Somlo Committed by Greg Kroah-Hartman
Browse files

serial: liteuart: add IRQ support for the RX path 



Add support for IRQ-driven RX. Support for the TX path will be added
in a separate commit.

Signed-off-by: default avatarGabriel Somlo <gsomlo@gmail.com>
Reviewed-by: default avatarIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Reviewed-by: default avatarJiri Slaby <jirislaby@kernel.org>
Link: https://lore.kernel.org/r/20221123130500.1030189-13-gsomlo@gmail.com


Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 7121d86e

drivers/tty/serial/liteuart.c

+74 −7
Original line number Diff line number Diff line
@@ -7,6 +7,7 @@ 


#include <linux/bits.h>

#include <linux/console.h>

#include <linux/interrupt.h>

#include <linux/litex.h>

#include <linux/module.h>

#include <linux/of.h>
@@ -46,6 +47,7 @@ struct liteuart_port { 
	struct uart_port port;

	struct timer_list timer;

	u32 id;

	u8 irq_reg;

};



#define to_liteuart_port(port)	container_of(port, struct liteuart_port, port)
@@ -76,6 +78,19 @@ static void liteuart_putchar(struct uart_port *port, unsigned char ch) 
	litex_write8(port->membase + OFF_RXTX, ch);

}



static void liteuart_update_irq_reg(struct uart_port *port, bool set, u8 mask)

{

	struct liteuart_port *uart = to_liteuart_port(port);



	if (set)

		uart->irq_reg |= mask;

	else

		uart->irq_reg &= ~mask;



	if (port->irq)

		litex_write8(port->membase + OFF_EV_ENABLE, uart->irq_reg);

}



static void liteuart_stop_tx(struct uart_port *port)

{

}
@@ -129,13 +144,32 @@ static void liteuart_rx_chars(struct uart_port *port) 
	tty_flip_buffer_push(&port->state->port);

}



static void liteuart_timer(struct timer_list *t)

static irqreturn_t liteuart_interrupt(int irq, void *data)

{

	struct liteuart_port *uart = from_timer(uart, t, timer);

	struct liteuart_port *uart = data;

	struct uart_port *port = &uart->port;

	unsigned long flags;

	u8 isr;



	/*

	 * if polling, the context would be "in_serving_softirq", so use

	 * irq[save|restore] spin_lock variants to cover all possibilities

	 */

	spin_lock_irqsave(&port->lock, flags);

	isr = litex_read8(port->membase + OFF_EV_PENDING) & uart->irq_reg;

	if (isr & EV_RX)

		liteuart_rx_chars(port);

	spin_unlock_irqrestore(&port->lock, flags);



	return IRQ_RETVAL(isr);

}



static void liteuart_timer(struct timer_list *t)

{

	struct liteuart_port *uart = from_timer(uart, t, timer);

	struct uart_port *port = &uart->port;



	liteuart_interrupt(0, port);

	mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));

}
@@ -161,19 +195,46 @@ static unsigned int liteuart_get_mctrl(struct uart_port *port) 
static int liteuart_startup(struct uart_port *port)

{

	struct liteuart_port *uart = to_liteuart_port(port);

	unsigned long flags;

	int ret;



	if (port->irq) {

		ret = request_irq(port->irq, liteuart_interrupt, 0,

				  KBUILD_MODNAME, uart);

		if (ret) {

			dev_warn(port->dev,

				"line %d irq %d failed: switch to polling\n",

				port->line, port->irq);

			port->irq = 0;

		}

	}



	/* disable events */

	litex_write8(port->membase + OFF_EV_ENABLE, 0);

	spin_lock_irqsave(&port->lock, flags);

	/* only enabling rx irqs during startup */

	liteuart_update_irq_reg(port, true, EV_RX);

	spin_unlock_irqrestore(&port->lock, flags);



	/* prepare timer for polling */

	if (!port->irq) {

		timer_setup(&uart->timer, liteuart_timer, 0);

		mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));

	}



	return 0;

}



static void liteuart_shutdown(struct uart_port *port)

{

	struct liteuart_port *uart = to_liteuart_port(port);

	unsigned long flags;



	spin_lock_irqsave(&port->lock, flags);

	liteuart_update_irq_reg(port, false, EV_RX | EV_TX);

	spin_unlock_irqrestore(&port->lock, flags);



	if (port->irq)

		free_irq(port->irq, port);

	else

		del_timer_sync(&uart->timer);

}



static void liteuart_set_termios(struct uart_port *port, struct ktermios *new,
@@ -262,6 +323,12 @@ static int liteuart_probe(struct platform_device *pdev) 
		goto err_erase_id;

	}



	ret = platform_get_irq_optional(pdev, 0);

	if (ret < 0 && ret != -ENXIO)

		return ret;

	if (ret > 0)

		port->irq = ret;



	/* values not from device tree */

	port->dev = &pdev->dev;

	port->iotype = UPIO_MEM;