[PATCH] serial: i.MX: evaluate linux,stdout-path property

[PATCH] serial: i.MX: evaluate linux,stdout-path property

[Sascha Hauer]

devicetrees may have the linux,stdout-path property to specify the
console. This patch adds support to the i.MX serial driver for this.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---

I was originally looking for a more generic way to handle this, but
since a struct console has no device associated to it, it's not
possible to match a console with a device in a generic way. So we
just call add_preferred_console from the driver and let it go down
to a string matching in the console code.
If anyone has a better idea how to handle this, please let me know.
Otherwise I'm happy to see this patch applied aswell.

Thanks
 Sascha

 drivers/tty/serial/imx.c |   29 +++++++++++++++++++++++++++++
 1 file changed, 29 insertions(+)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index e309e8b..b52c4a7 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1397,6 +1397,32 @@ static int serial_imx_resume(struct platform_device *dev)
 
 #ifdef CONFIG_OF
 /*
+ * Check if this device matches the linux,stdout-path property
+ * in the chosen node. return true if yes, false otherwise
+ */
+static int serial_imx_is_stdoutpath(struct platform_device *pdev)
+{
+	struct device_node *dn;
+	const char *name;
+
+	if (!IS_ENABLED(CONFIG_SERIAL_IMX_CONSOLE))
+		return 0;
+
+	name = of_get_property(of_chosen, "linux,stdout-path", NULL);
+	if (name == NULL)
+		return 0;
+
+	dn = of_find_node_by_path(name);
+	if (!dn)
+		return 0;
+
+	if (dn == pdev->dev.of_node)
+		return 1;
+
+	return 0;
+}
+
+/*
  * This function returns 1 iff pdev isn't a device instatiated by dt, 0 iff it
  * could successfully get all information from dt or a negative errno.
  */
@@ -1427,6 +1453,9 @@ static int serial_imx_probe_dt(struct imx_port *sport,
 
 	sport->devdata = of_id->data;
 
+	if (serial_imx_is_stdoutpath(pdev))
+		add_preferred_console(imx_reg.cons->name, sport->port.line, 0);
+
 	return 0;
 }
 #else
-- 
1.7.10.4

[PATCH] serial: i.MX: evaluate linux,stdout-path property

[Rob Herring]

On 10/04/2012 05:39 AM, Sascha Hauer wrote:
> devicetrees may have the linux,stdout-path property to specify the
> console. This patch adds support to the i.MX serial driver for this.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
> 
> I was originally looking for a more generic way to handle this, but
> since a struct console has no device associated to it, it's not
> possible to match a console with a device in a generic way. So we

Could we add a device ptr to struct console?

> just call add_preferred_console from the driver and let it go down
> to a string matching in the console code.
> If anyone has a better idea how to handle this, please let me know.
> Otherwise I'm happy to see this patch applied aswell.
> 
> Thanks
>  Sascha
> 
>  drivers/tty/serial/imx.c |   29 +++++++++++++++++++++++++++++
>  1 file changed, 29 insertions(+)
> 
> diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
> index e309e8b..b52c4a7 100644
> --- a/drivers/tty/serial/imx.c
> +++ b/drivers/tty/serial/imx.c
> @@ -1397,6 +1397,32 @@ static int serial_imx_resume(struct platform_device *dev)
>  
>  #ifdef CONFIG_OF
>  /*
> + * Check if this device matches the linux,stdout-path property
> + * in the chosen node. return true if yes, false otherwise
> + */
> +static int serial_imx_is_stdoutpath(struct platform_device *pdev)

Couldn't this function be generic? Just move
IS_ENABLED(CONFIG_SERIAL_IMX_CONSOLE) outside this function. Arguably,
the presence of the property or not could replace the config option all
together.

And use a struct device so this can work with devices other than
platform devices (i.e. amba).

Rob

> +{
> +	struct device_node *dn;
> +	const char *name;
> +
> +	if (!IS_ENABLED(CONFIG_SERIAL_IMX_CONSOLE))
> +		return 0;
> +
> +	name = of_get_property(of_chosen, "linux,stdout-path", NULL);
> +	if (name == NULL)
> +		return 0;
> +
> +	dn = of_find_node_by_path(name);
> +	if (!dn)
> +		return 0;
> +
> +	if (dn == pdev->dev.of_node)
> +		return 1;
> +
> +	return 0;
> +}
> +
> +/*
>   * This function returns 1 iff pdev isn't a device instatiated by dt, 0 iff it
>   * could successfully get all information from dt or a negative errno.
>   */
> @@ -1427,6 +1453,9 @@ static int serial_imx_probe_dt(struct imx_port *sport,
>  
>  	sport->devdata = of_id->data;
>  
> +	if (serial_imx_is_stdoutpath(pdev))
> +		add_preferred_console(imx_reg.cons->name, sport->port.line, 0);
> +
>  	return 0;
>  }
>  #else
> 

[PATCH] serial: i.MX: evaluate linux,stdout-path property

[Sascha Hauer]

On Thu, Oct 04, 2012 at 07:44:45AM -0500, Rob Herring wrote:
> On 10/04/2012 05:39 AM, Sascha Hauer wrote:
> > devicetrees may have the linux,stdout-path property to specify the
> > console. This patch adds support to the i.MX serial driver for this.
> > 
> > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> > ---
> > 
> > I was originally looking for a more generic way to handle this, but
> > since a struct console has no device associated to it, it's not
> > possible to match a console with a device in a generic way. So we
> 
> Could we add a device ptr to struct console?

I think not. Looking at some drivers they register a console very early
when there is no device available (even if there will be a device later
when the uart driver probes)

> >  #ifdef CONFIG_OF
> >  /*
> > + * Check if this device matches the linux,stdout-path property
> > + * in the chosen node. return true if yes, false otherwise
> > + */
> > +static int serial_imx_is_stdoutpath(struct platform_device *pdev)
> 
> Couldn't this function be generic? Just move
> IS_ENABLED(CONFIG_SERIAL_IMX_CONSOLE) outside this function. Arguably,
> the presence of the property or not could replace the config option all
> together.
> 
> And use a struct device so this can work with devices other than
> platform devices (i.e. amba).

Ok, makes sense.

Sascha

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