[PATCH 2/5] altera_uart: Add support for polling mode (IRQ-less)

[PATCH 2/5] altera_uart: Add support for polling mode (IRQ-less)

[Anton Vorontsov]

Some Altera UART implementations doesn't route the IRQ line, so we have
to work in polling mode.

Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
---
 drivers/serial/altera_uart.c |   38 +++++++++++++++++++++++++++++---------
 1 files changed, 29 insertions(+), 9 deletions(-)

diff --git a/drivers/serial/altera_uart.c b/drivers/serial/altera_uart.c
index f8d8a00..2603f59 100644
--- a/drivers/serial/altera_uart.c
+++ b/drivers/serial/altera_uart.c
@@ -15,6 +15,7 @@
 
 #include <linux/kernel.h>
 #include <linux/init.h>
+#include <linux/timer.h>
 #include <linux/interrupt.h>
 #include <linux/module.h>
 #include <linux/console.h>
@@ -76,6 +77,7 @@
  */
 struct altera_uart {
 	struct uart_port port;
+	struct timer_list tmr;
 	unsigned int sigs;	/* Local copy of line sigs */
 	unsigned short imr;	/* Local IMR mirror */
 };
@@ -168,6 +170,7 @@ static void altera_uart_set_termios(struct uart_port *port,
 	tty_termios_encode_baud_rate(termios, baud, baud);
 
 	spin_lock_irqsave(&port->lock, flags);
+	uart_update_timeout(port, termios->c_cflag, baud);
 	writel(baudclk, port->membase + ALTERA_UART_DIVISOR_REG);
 	spin_unlock_irqrestore(&port->lock, flags);
 }
@@ -268,6 +271,15 @@ static irqreturn_t altera_uart_interrupt(int irq, void *data)
 	return IRQ_RETVAL(isr);
 }
 
+static void altera_uart_timer(unsigned long data)
+{
+	struct uart_port *port = (void *)data;
+	struct altera_uart *pp = container_of(port, struct altera_uart, port);
+
+	altera_uart_interrupt(0, port);
+	mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
+}
+
 static void altera_uart_config_port(struct uart_port *port, int flags)
 {
 	port->type = PORT_ALTERA_UART;
@@ -284,14 +296,6 @@ static int altera_uart_startup(struct uart_port *port)
 	unsigned long flags;
 	int ret;
 
-	ret = request_irq(port->irq, altera_uart_interrupt, IRQF_DISABLED,
-			DRV_NAME, port);
-	if (ret) {
-		pr_err(DRV_NAME ": unable to attach Altera UART %d "
-		       "interrupt vector=%d\n", port->line, port->irq);
-		return ret;
-	}
-
 	spin_lock_irqsave(&port->lock, flags);
 
 	/* Enable RX interrupts now */
@@ -300,6 +304,19 @@ static int altera_uart_startup(struct uart_port *port)
 
 	spin_unlock_irqrestore(&port->lock, flags);
 
+	if (port->irq) {
+		ret = request_irq(port->irq, altera_uart_interrupt,
+				  IRQF_DISABLED, DRV_NAME, port);
+		if (ret) {
+			pr_err(DRV_NAME ": unable to attach Altera UART %d "
+			       "interrupt vector=%d\n", port->line, port->irq);
+			return ret;
+		}
+	} else {
+		setup_timer(&pp->tmr, altera_uart_timer, (unsigned long)port);
+		mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
+	}
+
 	return 0;
 }
 
@@ -316,7 +333,10 @@ static void altera_uart_shutdown(struct uart_port *port)
 
 	spin_unlock_irqrestore(&port->lock, flags);
 
-	free_irq(port->irq, port);
+	if (port->irq)
+		free_irq(port->irq, port);
+	else
+		del_timer_sync(&pp->tmr);
 }
 
 static const char *altera_uart_type(struct uart_port *port)
-- 
1.7.0.5

Re: [PATCH 2/5] altera_uart: Add support for polling mode (IRQ-less)

[Tobias Klauser]

On 2010-09-28 at 15:35:26 +0200, Anton Vorontsov <cbouatmailru@gmail.com> wrote:
> Some Altera UART implementations doesn't route the IRQ line, so we have
> to work in polling mode.
> 
> Signed-off-by: Anton Vorontsov <cbouatmailru@gmail.com>
> ---
>  drivers/serial/altera_uart.c |   38 +++++++++++++++++++++++++++++---------
>  1 files changed, 29 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/serial/altera_uart.c b/drivers/serial/altera_uart.c
> index f8d8a00..2603f59 100644
> --- a/drivers/serial/altera_uart.c
> +++ b/drivers/serial/altera_uart.c
> @@ -15,6 +15,7 @@
>  
>  #include <linux/kernel.h>
>  #include <linux/init.h>
> +#include <linux/timer.h>
>  #include <linux/interrupt.h>
>  #include <linux/module.h>
>  #include <linux/console.h>
> @@ -76,6 +77,7 @@
>   */
>  struct altera_uart {
>  	struct uart_port port;
> +	struct timer_list tmr;
>  	unsigned int sigs;	/* Local copy of line sigs */
>  	unsigned short imr;	/* Local IMR mirror */
>  };
> @@ -168,6 +170,7 @@ static void altera_uart_set_termios(struct uart_port *port,
>  	tty_termios_encode_baud_rate(termios, baud, baud);
>  
>  	spin_lock_irqsave(&port->lock, flags);
> +	uart_update_timeout(port, termios->c_cflag, baud);
>  	writel(baudclk, port->membase + ALTERA_UART_DIVISOR_REG);
>  	spin_unlock_irqrestore(&port->lock, flags);
>  }
> @@ -268,6 +271,15 @@ static irqreturn_t altera_uart_interrupt(int irq, void *data)
>  	return IRQ_RETVAL(isr);
>  }
>  
> +static void altera_uart_timer(unsigned long data)
> +{
> +	struct uart_port *port = (void *)data;
> +	struct altera_uart *pp = container_of(port, struct altera_uart, port);
> +
> +	altera_uart_interrupt(0, port);
> +	mod_timer(&pp->tmr, jiffies + uart_poll_timeout(port));
> +}
> +
>  static void altera_uart_config_port(struct uart_port *port, int flags)
>  {
>  	port->type = PORT_ALTERA_UART;
> @@ -284,14 +296,6 @@ static int altera_uart_startup(struct uart_port *port)
>  	unsigned long flags;
>  	int ret;
>  
> -	ret = request_irq(port->irq, altera_uart_interrupt, IRQF_DISABLED,
> -			DRV_NAME, port);
> -	if (ret) {
> -		pr_err(DRV_NAME ": unable to attach Altera UART %d "
> -		       "interrupt vector=%d\n", port->line, port->irq);
> -		return ret;
> -	}
> -
>  	spin_lock_irqsave(&port->lock, flags);
>  
>  	/* Enable RX interrupts now */
> @@ -300,6 +304,19 @@ static int altera_uart_startup(struct uart_port *port)
>  
>  	spin_unlock_irqrestore(&port->lock, flags);

Shouldn't we only enable the RX interrupt if we actually use interrupts?
Also I would retain the order here (first register the interrupt handler
and then enable the interrupts).

Cheers,
  Tobias

Re: [PATCH 2/5] altera_uart: Add support for polling mode (IRQ-less)

[Anton Vorontsov]

On Tue, Sep 28, 2010 at 05:45:39PM +0200, Tobias Klauser wrote:
[...]
> > -	ret = request_irq(port->irq, altera_uart_interrupt, IRQF_DISABLED,
> > -			DRV_NAME, port);
> > -	if (ret) {
> > -		pr_err(DRV_NAME ": unable to attach Altera UART %d "
> > -		       "interrupt vector=%d\n", port->line, port->irq);
> > -		return ret;
> > -	}
> > -
> >  	spin_lock_irqsave(&port->lock, flags);
> >  
> >  	/* Enable RX interrupts now */
> > @@ -300,6 +304,19 @@ static int altera_uart_startup(struct uart_port *port)
> >  
> >  	spin_unlock_irqrestore(&port->lock, flags);
> 
> Shouldn't we only enable the RX interrupt if we actually use interrupts?

Why would that matter if we don't use the interrupts? ;-)

But I made the change anyway.

> Also I would retain the order here (first register the interrupt handler
> and then enable the interrupts).

OK, fixed. Thanks!

-- 
Anton Vorontsov
email: cbouatmailru@gmail.com
irc://irc.freenode.net/bd2