[PATCH] Add keyboard blink driver

[PATCH] Add keyboard blink driver

[Andi Kleen]

Add a blink driver for debugging

Simple driver that blinks the keyboard LEDs when loaded. Useful
for checking that the kernel is still alive or for crashdumping.
The kdump kernel currently typically doesn't give any feedback
on the screen because it often cannot reinitialize the graphics
state. This patch allows it to at least show blinking lights
like panic.

Signed-off-by: Andi Kleen <ak@suse.de>

---
 drivers/misc/Kconfig  |    9 +++++++++
 drivers/misc/Makefile |    1 +
 drivers/misc/blink.c  |   26 ++++++++++++++++++++++++++
 3 files changed, 36 insertions(+)

Index: linux/drivers/misc/Kconfig
===================================================================
--- linux.orig/drivers/misc/Kconfig
+++ linux/drivers/misc/Kconfig
@@ -107,4 +107,13 @@ config MSI_LAPTOP
 
 	  If you have an MSI S270 laptop, say Y or M here.
 
+config BLINK
+	tristate "Keyboard blink driver"
+	help
+	  Driver that when loaded will blink the keyboard LEDs continuously.
+	  This is useful for debugging and for kernels that cannot necessarily
+	  output something to the screen like kexec kernels to give the user
+	  a visual indication that the kernel is doing something.
+
+
 endmenu
Index: linux/drivers/misc/Makefile
===================================================================
--- linux.orig/drivers/misc/Makefile
+++ linux/drivers/misc/Makefile
@@ -11,3 +11,4 @@ obj-$(CONFIG_LKDTM)		+= lkdtm.o
 obj-$(CONFIG_TIFM_CORE)       	+= tifm_core.o
 obj-$(CONFIG_TIFM_7XX1)       	+= tifm_7xx1.o
 obj-$(CONFIG_SGI_IOC4)		+= ioc4.o
+obj-$(CONFIG_BLINK)		+= blink.o
Index: linux/drivers/misc/blink.c
===================================================================
--- /dev/null
+++ linux/drivers/misc/blink.c
@@ -0,0 +1,26 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+
+static void do_blink(unsigned long data);
+
+static DEFINE_TIMER(blink_timer, do_blink, 0 ,0);
+
+static void do_blink(unsigned long data)
+{
+	static long count;
+	panic_blink(count++);
+	blink_timer.expires = jiffies + msecs_to_jiffies(1);
+	add_timer(&blink_timer);
+}
+
+static int blink_init(void)
+{
+	printk(KERN_INFO "Enabling keyboard blinking\n");
+	do_blink(0);
+	return 0;
+}
+
+module_init(blink_init);
+

Re: [PATCH] Add keyboard blink driver

[Andrew Morton]

On Thu, 12 Apr 2007 17:27:27 +0200
Andi Kleen <ak@novell.com> wrote:

> Add a blink driver for debugging
> 
> Simple driver that blinks the keyboard LEDs when loaded. Useful
> for checking that the kernel is still alive or for crashdumping.
> The kdump kernel currently typically doesn't give any feedback
> on the screen because it often cannot reinitialize the graphics
> state. This patch allows it to at least show blinking lights
> like panic.

OK..

> --- /dev/null
> +++ linux/drivers/misc/blink.c
> @@ -0,0 +1,26 @@
> +#include <linux/kernel.h>
> +#include <linux/module.h>
> +#include <linux/timer.h>
> +#include <linux/jiffies.h>
> +
> +static void do_blink(unsigned long data);
> +
> +static DEFINE_TIMER(blink_timer, do_blink, 0 ,0);
> +
> +static void do_blink(unsigned long data)
> +{
> +	static long count;
> +	panic_blink(count++);
> +	blink_timer.expires = jiffies + msecs_to_jiffies(1);
> +	add_timer(&blink_timer);
> +}
> +
> +static int blink_init(void)
> +{
> +	printk(KERN_INFO "Enabling keyboard blinking\n");
> +	do_blink(0);
> +	return 0;
> +}
> +
> +module_init(blink_init);

panic_blink is NULL in lots of setups.  `modprobe blink' will be deadly.

I wonder if this facility would be more effective if it were to use
schedule_delayed_work().  That way, we're using more of the kernel and it
will more reliably detect kernel deadness.

Re: [PATCH] Add keyboard blink driver

[Andi Kleen]

On Thursday 12 April 2007 21:10:28 Andrew Morton wrote:
> On Thu, 12 Apr 2007 17:27:27 +0200
> Andi Kleen <ak@novell.com> wrote:
> 
> > Add a blink driver for debugging
> > 
> > Simple driver that blinks the keyboard LEDs when loaded. Useful
> > for checking that the kernel is still alive or for crashdumping.
> > The kdump kernel currently typically doesn't give any feedback
> > on the screen because it often cannot reinitialize the graphics
> > state. This patch allows it to at least show blinking lights
> > like panic.
> 
> OK..
> 
> > --- /dev/null
> > +++ linux/drivers/misc/blink.c
> > @@ -0,0 +1,26 @@
> > +#include <linux/kernel.h>
> > +#include <linux/module.h>
> > +#include <linux/timer.h>
> > +#include <linux/jiffies.h>
> > +
> > +static void do_blink(unsigned long data);
> > +
> > +static DEFINE_TIMER(blink_timer, do_blink, 0 ,0);
> > +
> > +static void do_blink(unsigned long data)
> > +{
> > +	static long count;
> > +	panic_blink(count++);
> > +	blink_timer.expires = jiffies + msecs_to_jiffies(1);
> > +	add_timer(&blink_timer);
> > +}
> > +
> > +static int blink_init(void)
> > +{
> > +	printk(KERN_INFO "Enabling keyboard blinking\n");
> > +	do_blink(0);
> > +	return 0;
> > +}
> > +
> > +module_init(blink_init);
> 
> panic_blink is NULL in lots of setups.  `modprobe blink' will be deadly.

Oops sorry -- i must somehow have sent an old patch. I had fixed this of course
Ahh, quilt refresh was missing.

See the new patch.
 
> I wonder if this facility would be more effective if it were to use
> schedule_delayed_work().  That way, we're using more of the kernel and it
> will more reliably detect kernel deadness.
 
Hmm, maybe

-Andi

Add a blink driver for debugging

Simple driver that blinks the keyboard LEDs when loaded. Useful
for checking that the kernel is still alive or for crashdumping

Signed-off-by: Andi Kleen <ak@suse.de>

---
 drivers/misc/Kconfig  |    9 +++++++++
 drivers/misc/Makefile |    1 +
 drivers/misc/blink.c  |   26 ++++++++++++++++++++++++++
 3 files changed, 36 insertions(+)

Index: linux-2.6.21-rc6-test/drivers/misc/Kconfig
===================================================================
--- linux-2.6.21-rc6-test.orig/drivers/misc/Kconfig
+++ linux-2.6.21-rc6-test/drivers/misc/Kconfig
@@ -122,4 +122,13 @@ config SONY_LAPTOP
 
 	  Read <file:Documentation/sony-laptop.txt> for more information.
 
+config BLINK
+	tristate "Keyboard blink driver"
+	help
+	  Driver that when loaded will blink the keyboard LEDs continuously.
+	  This is useful for debugging and for kernels that cannot necessarily
+	  output something to the screen like kexec kernels to give the user
+	  a visual indication that the kernel is doing something.
+
+
 endmenu
Index: linux-2.6.21-rc6-test/drivers/misc/Makefile
===================================================================
--- linux-2.6.21-rc6-test.orig/drivers/misc/Makefile
+++ linux-2.6.21-rc6-test/drivers/misc/Makefile
@@ -12,3 +12,4 @@ obj-$(CONFIG_TIFM_CORE)       	+= tifm_c
 obj-$(CONFIG_TIFM_7XX1)       	+= tifm_7xx1.o
 obj-$(CONFIG_SGI_IOC4)		+= ioc4.o
 obj-$(CONFIG_SONY_LAPTOP)	+= sony-laptop.o
+obj-$(CONFIG_BLINK)		+= blink.o
Index: linux-2.6.21-rc6-test/drivers/misc/blink.c
===================================================================
--- /dev/null
+++ linux-2.6.21-rc6-test/drivers/misc/blink.c
@@ -0,0 +1,27 @@
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/timer.h>
+#include <linux/jiffies.h>
+
+static void do_blink(unsigned long data);
+
+static DEFINE_TIMER(blink_timer, do_blink, 0 ,0);
+
+static void do_blink(unsigned long data)
+{
+	static long count;
+	if (panic_blink)
+		panic_blink(count++);
+	blink_timer.expires = jiffies + msecs_to_jiffies(1);
+	add_timer(&blink_timer);
+}
+
+static int blink_init(void)
+{
+	printk(KERN_INFO "Enabling keyboard blinking\n");
+	do_blink(0);
+	return 0;
+}
+
+module_init(blink_init);
+

Re: [PATCH] Add keyboard blink driver

[Andrew Morton]

On Thu, 12 Apr 2007 21:28:08 +0200
Andi Kleen <ak@novell.com> wrote:

> > I wonder if this facility would be more effective if it were to use
> > schedule_delayed_work().  That way, we're using more of the kernel and it
> > will more reliably detect kernel deadness.
>  
> Hmm, maybe

??

> +static void do_blink(unsigned long data)
> +{
> +	static long count;
> +	if (panic_blink)
> +		panic_blink(count++);
> +	blink_timer.expires = jiffies + msecs_to_jiffies(1);
> +	add_timer(&blink_timer);
> +}
> +
> +static int blink_init(void)
> +{
> +	printk(KERN_INFO "Enabling keyboard blinking\n");
> +	do_blink(0);
> +	return 0;
> +}

Would it be better to just not start the timer at all if panic_blink==0? 
That would improve life rather a lot for people who link this into vmlinux
but don't have i8042.

Re: [PATCH] Add keyboard blink driver

[Pavel Machek]

Hi!

> Add a blink driver for debugging
> 
> Simple driver that blinks the keyboard LEDs when loaded. Useful
> for checking that the kernel is still alive or for crashdumping.

For checking if kernel is alive/crashdumping... can user just do
setleds +caps; sleep 1; setleds -caps; ... ? You can even have morse
code :-).

Besides, we now have led support framework in kernel, that can do
blinking by itself etc.
								Pavel


-- 
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