[PATCH v4] linux,stdout-path helper

[PATCH v4] linux,stdout-path helper

[Sascha Hauer]

The following adds a helper for matching the linux,stdout-path property
in the chosen node and makes use of it in the i.MX serial driver.

changes since v3:

- move code from separate files to drivers/of/base.c and include/linux/of.h

changes since v2:

- move helper to OF core and make it independent of serial devices

changes since v1:

- move it out of the i.MX serial driver and make it generic for serial
  devices.

[PATCH 1/3] OF: Add helper for matching against linux,stdout-path

[Sascha Hauer]

devicetrees may have a linux,stdout-path property in the chosen
node describing the console device. This adds a helper function
to match a device against this property so a driver can call
add_preferred_console for a matching device.

Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
 drivers/of/base.c  |   28 ++++++++++++++++++++++++++++
 include/linux/of.h |    7 +++++++
 2 files changed, 35 insertions(+)

diff --git a/drivers/of/base.c b/drivers/of/base.c
index af3b22a..737feb8 100644
--- a/drivers/of/base.c
+++ b/drivers/of/base.c
@@ -1358,3 +1358,31 @@ const char *of_prop_next_string(struct property *prop, const char *cur)
 	return curv;
 }
 EXPORT_SYMBOL_GPL(of_prop_next_string);
+
+/**
+ * of_device_is_stdout_path - check if a device node matches the
+ *                            linux,stdout-path property
+ *
+ * Check if this device node matches the linux,stdout-path property
+ * in the chosen node. return true if yes, false otherwise.
+ */
+int of_device_is_stdout_path(struct device_node *dn)
+{
+	const char *name;
+	struct device_node *dn_stdout;
+	int is_stdout = 0;
+
+	name = of_get_property(of_chosen, "linux,stdout-path", NULL);
+	if (name == NULL)
+		return 0;
+
+	dn_stdout = of_find_node_by_path(name);
+
+	if (dn_stdout && dn_stdout == dn)
+		is_stdout = 1;
+
+	of_node_put(dn_stdout);
+
+	return is_stdout;
+}
+EXPORT_SYMBOL_GPL(of_device_is_stdout_path);
diff --git a/include/linux/of.h b/include/linux/of.h
index b4e50d5..5f857b5 100644
--- a/include/linux/of.h
+++ b/include/linux/of.h
@@ -310,6 +310,8 @@ const char *of_prop_next_string(struct property *prop, const char *cur);
 		s;						\
 		s = of_prop_next_string(prop, s))
 
+int of_device_is_stdout_path(struct device_node *dn);
+
 #else /* CONFIG_OF */
 
 static inline const char* of_node_full_name(struct device_node *np)
@@ -437,6 +439,11 @@ static inline int of_machine_is_compatible(const char *compat)
 	return 0;
 }
 
+static inline int of_device_is_stdout_path(struct device_node *dn)
+{
+	return 0;
+}
+
 #define of_match_ptr(_ptr)	NULL
 #define of_match_node(_matches, _node)	NULL
 #define of_property_for_each_u32(np, propname, prop, p, u) \
-- 
1.7.10.4

Re: [PATCH 1/3] OF: Add helper for matching against linux,stdout-path

[Jean-Christophe PLAGNIOL-VILLARD]

On 10:31 Thu 15 Nov     , Sascha Hauer wrote:
> devicetrees may have a linux,stdout-path property in the chosen
> node describing the console device. This adds a helper function
> to match a device against this property so a driver can call
> add_preferred_console for a matching device.

I like it but I've an issue with it I cannot specify the option for

as example I need to set the uart at 38400n8 or 115200n8 regarless of wath the
booloader did

Best Regards,
J.
> 
> Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
> ---
>  drivers/of/base.c  |   28 ++++++++++++++++++++++++++++
>  include/linux/of.h |    7 +++++++
>  2 files changed, 35 insertions(+)
> 
> diff --git a/drivers/of/base.c b/drivers/of/base.c
> index af3b22a..737feb8 100644
> --- a/drivers/of/base.c
> +++ b/drivers/of/base.c
> @@ -1358,3 +1358,31 @@ const char *of_prop_next_string(struct property *prop, const char *cur)
>  	return curv;
>  }
>  EXPORT_SYMBOL_GPL(of_prop_next_string);
> +
> +/**
> + * of_device_is_stdout_path - check if a device node matches the
> + *                            linux,stdout-path property
> + *
> + * Check if this device node matches the linux,stdout-path property
> + * in the chosen node. return true if yes, false otherwise.
> + */
> +int of_device_is_stdout_path(struct device_node *dn)
> +{
> +	const char *name;
> +	struct device_node *dn_stdout;
> +	int is_stdout = 0;
> +
> +	name = of_get_property(of_chosen, "linux,stdout-path", NULL);
> +	if (name == NULL)
> +		return 0;
> +
> +	dn_stdout = of_find_node_by_path(name);
> +
> +	if (dn_stdout && dn_stdout == dn)
> +		is_stdout = 1;
> +
> +	of_node_put(dn_stdout);
> +
> +	return is_stdout;
> +}
> +EXPORT_SYMBOL_GPL(of_device_is_stdout_path);
> diff --git a/include/linux/of.h b/include/linux/of.h
> index b4e50d5..5f857b5 100644
> --- a/include/linux/of.h
> +++ b/include/linux/of.h
> @@ -310,6 +310,8 @@ const char *of_prop_next_string(struct property *prop, const char *cur);
>  		s;						\
>  		s = of_prop_next_string(prop, s))
>  
> +int of_device_is_stdout_path(struct device_node *dn);
> +
>  #else /* CONFIG_OF */
>  
>  static inline const char* of_node_full_name(struct device_node *np)
> @@ -437,6 +439,11 @@ static inline int of_machine_is_compatible(const char *compat)
>  	return 0;
>  }
>  
> +static inline int of_device_is_stdout_path(struct device_node *dn)
> +{
> +	return 0;
> +}
> +
>  #define of_match_ptr(_ptr)	NULL
>  #define of_match_node(_matches, _node)	NULL
>  #define of_property_for_each_u32(np, propname, prop, p, u) \
> -- 
> 1.7.10.4
> 
> _______________________________________________
> devicetree-discuss mailing list
> devicetree-discuss@lists.ozlabs.org
> https://lists.ozlabs.org/listinfo/devicetree-discuss

Re: [PATCH 1/3] OF: Add helper for matching against linux,stdout-path

[Grant Likely]

On Mon, 19 Nov 2012 10:52:02 +0100, Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com> wrote:
> On 10:31 Thu 15 Nov     , Sascha Hauer wrote:
> > devicetrees may have a linux,stdout-path property in the chosen
> > node describing the console device. This adds a helper function
> > to match a device against this property so a driver can call
> > add_preferred_console for a matching device.
> 
> I like it but I've an issue with it I cannot specify the option for
> 
> as example I need to set the uart at 38400n8 or 115200n8 regarless of wath the
> booloader did

Right. stdout-path can have a set of arguments appended for things like
serial speed.  ePAPR says this about stdout-path:

A string that specifies the full path to the node representing the
device to be used for boot console output. If the character ":" is
present in the value it terminates the path. The value may be an alias.

If the stdin-path property is not specified, stdout-path should be
assumed to define the input device.

So, this function needs to do three more things:
- also look for 'stdout-path' (in addition to 'linux,stdout-path')
- Parse for a ':' in the path and trim that off so it can be used for
  arguments. (Bonus: return the arguments to the caller)
- make sure that it can handle the path containing an alias (I've just
  not checked if the current code will handle this)

g.

[PATCH 2/3] serial: i.MX: Make console support non optional

[Sascha Hauer]

Traditionally console support is optional for serial drivers. This
makes it non optional for the i.MX driver since it's not worth
asking questions for a feature virtually every user of this driver
wants to have.

Signed-off-by: Sascha Hauer <s.hauer-bIcnvbaLZ9MEGnE8C9+IrQ@public.gmane.org>
---
 drivers/tty/serial/Kconfig |   16 +---------------
 drivers/tty/serial/imx.c   |    8 +-------
 2 files changed, 2 insertions(+), 22 deletions(-)

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 2a53be5..919b243 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -541,26 +541,12 @@ config SERIAL_IMX
 	bool "IMX serial port support"
 	depends on ARCH_MXC
 	select SERIAL_CORE
+	select SERIAL_CORE_CONSOLE
 	select RATIONAL
 	help
 	  If you have a machine based on a Motorola IMX CPU you
 	  can enable its onboard serial port by enabling this option.
 
-config SERIAL_IMX_CONSOLE
-	bool "Console on IMX serial port"
-	depends on SERIAL_IMX
-	select SERIAL_CORE_CONSOLE
-	help
-	  If you have enabled the serial port on the Motorola IMX
-	  CPU you can make it the console by answering Y to this option.
-
-	  Even if you say Y here, the currently visible virtual console
-	  (/dev/tty0) will still be used as the system console by default, but
-	  you can alter that using a kernel command line option such as
-	  "console=ttySA0". (Try "man bootparam" or see the documentation of
-	  your boot loader (lilo or loadlin) about how to pass options to the
-	  kernel at boot time.)
-
 config SERIAL_UARTLITE
 	tristate "Xilinx uartlite serial port support"
 	depends on PPC32 || MICROBLAZE || MFD_TIMBERDALE
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 5981912..07a8ca1 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1192,7 +1192,6 @@ static struct uart_ops imx_pops = {
 
 static struct imx_port *imx_ports[UART_NR];
 
-#ifdef CONFIG_SERIAL_IMX_CONSOLE
 static void imx_console_putchar(struct uart_port *port, int ch)
 {
 	struct imx_port *sport = (struct imx_port *)port;
@@ -1348,11 +1347,6 @@ static struct console imx_console = {
 	.data		= &imx_reg,
 };
 
-#define IMX_CONSOLE	&imx_console
-#else
-#define IMX_CONSOLE	NULL
-#endif
-
 static struct uart_driver imx_reg = {
 	.owner          = THIS_MODULE,
 	.driver_name    = DRIVER_NAME,
@@ -1360,7 +1354,7 @@ static struct uart_driver imx_reg = {
 	.major          = SERIAL_IMX_MAJOR,
 	.minor          = MINOR_START,
 	.nr             = ARRAY_SIZE(imx_ports),
-	.cons           = IMX_CONSOLE,
+	.cons           = &imx_console,
 };
 
 static int serial_imx_suspend(struct platform_device *dev, pm_message_t state)
-- 
1.7.10.4

[PATCH 3/3] 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>
---
 drivers/tty/serial/imx.c |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index 07a8ca1..ac5a679 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1419,6 +1419,9 @@ static int serial_imx_probe_dt(struct imx_port *sport,
 
 	sport->devdata = of_id->data;
 
+	if (of_device_is_stdout_path(np))
+		add_preferred_console(imx_reg.cons->name, sport->port.line, 0);
+
 	return 0;
 }
 #else
-- 
1.7.10.4