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Message-Id: <20221110004450.772768-8-gsomlo@gmail.com>
Date: Wed, 9 Nov 2022 19:44:50 -0500
From: Gabriel Somlo <gsomlo@...il.com>
To: linux-kernel@...r.kernel.org
Cc: linux-serial@...r.kernel.org, gregkh@...uxfoundation.org,
jirislaby@...nel.org, kgugala@...micro.com, mholenko@...micro.com,
joel@....id.au, david.abdurachmanov@...il.com,
florent@...oy-digital.fr, geert@...ux-m68k.org
Subject: [PATCH v2 7/7] serial: liteuart: add IRQ support
Add support for IRQ-driven RX. The TX path remains "polling" based,
which is fine since TX is synchronous.
Signed-off-by: Gabriel Somlo <gsomlo@...il.com>
---
drivers/tty/serial/liteuart.c | 66 +++++++++++++++++++++++++++++++----
1 file changed, 59 insertions(+), 7 deletions(-)
diff --git a/drivers/tty/serial/liteuart.c b/drivers/tty/serial/liteuart.c
index aa7052280197..45da944d1fea 100644
--- a/drivers/tty/serial/liteuart.c
+++ b/drivers/tty/serial/liteuart.c
@@ -6,6 +6,7 @@
*/
#include <linux/console.h>
+#include <linux/interrupt.h>
#include <linux/litex.h>
#include <linux/module.h>
#include <linux/of.h>
@@ -88,13 +89,27 @@ static void liteuart_rx_chars(struct uart_port *port)
tty_flip_buffer_push(&port->state->port);
}
+static irqreturn_t liteuart_interrupt(int irq, void *data)
+{
+ struct uart_port *port = data;
+ unsigned int isr;
+
+ isr = litex_read32(port->membase + OFF_EV_PENDING);
+
+ spin_lock(&port->lock);
+ if (isr & EV_RX)
+ liteuart_rx_chars(port);
+ spin_unlock(&port->lock);
+
+ 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_rx_chars(port);
-
+ liteuart_interrupt(0, port);
mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
}
@@ -163,19 +178,49 @@ static void liteuart_stop_rx(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;
+ u8 irq_mask = 0;
- /* disable events */
- litex_write8(port->membase + OFF_EV_ENABLE, 0);
+ if (port->irq) {
+ ret = request_irq(port->irq, liteuart_interrupt, 0,
+ KBUILD_MODNAME, port);
+ if (ret == 0) {
+ /* we only need interrupts on the rx path! */
+ irq_mask = EV_RX;
+ } else {
+ pr_err(KBUILD_MODNAME ": can't attach LiteUART %d "
+ "irq %d; switching to polling\n",
+ port->line, port->irq);
+ port->irq = 0;
+ }
+ }
- /* prepare timer for polling */
- timer_setup(&uart->timer, liteuart_timer, 0);
- mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
+ if (!port->irq) {
+ timer_setup(&uart->timer, liteuart_timer, 0);
+ mod_timer(&uart->timer, jiffies + uart_poll_timeout(port));
+ }
+
+ spin_lock_irqsave(&port->lock, flags);
+ litex_write8(port->membase + OFF_EV_ENABLE, irq_mask);
+ spin_unlock_irqrestore(&port->lock, flags);
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);
+ litex_write8(port->membase + OFF_EV_ENABLE, 0);
+ 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,
@@ -264,6 +309,13 @@ static int liteuart_probe(struct platform_device *pdev)
goto err_erase_id;
}
+ /* get irq */
+ 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;
--
2.37.3
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