[PATCH] Allow arch to veto PC speaker beeper initialization

[PATCH] Allow arch to veto PC speaker beeper initialization

[Paul Mackerras]

From: Michael Neuling <mikey@neuling.org>

This patch provides an arch hook in the PC speaker beeper driver which
gives the arch code an opportunity to determine whether the machine
has an i8253 timer or not.  If it doesn't we don't want the driver to
go poking at the i8253's ports; there might be nothing there or there
might be something else there which would be upset by being poked at.

We want to be able to build ppc64 kernels which work both on machines
that have an i8253 equivalent (e.g. some pSeries) and on machines that
don't (e.g. G5 powermacs), which is why we don't just remove it from
the config.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>
---

Could this go in please, preferably for 2.6.15?  Some people are
finding that their G5 powermacs lock up when this driver pokes the PIT
registers.

 drivers/input/misc/pcspkr.c   |    5 +++++
 include/asm-powerpc/8253pit.h |   13 +++++++++++++
 2 files changed, 18 insertions(+)

Index: linux-2.6/drivers/input/misc/pcspkr.c
===================================================================
--- linux-2.6.orig/drivers/input/misc/pcspkr.c	2005-10-31 15:16:39.000000000 +1100
+++ linux-2.6/drivers/input/misc/pcspkr.c	2005-10-31 15:21:13.000000000 +1100
@@ -66,6 +66,11 @@
 
 static int __init pcspkr_init(void)
 {
+#ifdef HAS_PCSPKR_ARCH_INIT
+	int rc = pcspkr_arch_init();
+	if (rc)
+		return rc;
+#endif
 	pcspkr_dev = input_allocate_device();
 	if (!pcspkr_dev)
 		return -ENOMEM;
Index: linux-2.6/include/asm-powerpc/8253pit.h
===================================================================
--- linux-2.6.orig/include/asm-powerpc/8253pit.h	2005-10-31 15:02:18.000000000 +1100
+++ linux-2.6/include/asm-powerpc/8253pit.h	2005-10-31 15:20:30.000000000 +1100
@@ -5,6 +5,19 @@
  * 8253/8254 Programmable Interval Timer
  */
 
+#include <asm/prom.h>
+
 #define PIT_TICK_RATE	1193182UL
 
+#define HAS_PCSPKR_ARCH_INIT
+
+static inline int pcspkr_arch_init(void)
+{
+	struct device_node *np;
+
+	np = of_find_compatible_node(NULL, NULL, "pnpPNP,100");
+	of_node_put(np);
+	return np ? 0 : -ENODEV;
+}
+
 #endif	/* _ASM_POWERPC_8253PIT_H */

Re: [PATCH] Allow arch to veto PC speaker beeper initialization

[Andrew Morton]

Paul Mackerras <paulus@samba.org> wrote:
>
> Index: linux-2.6/drivers/input/misc/pcspkr.c
> ===================================================================
> --- linux-2.6.orig/drivers/input/misc/pcspkr.c	2005-10-31 15:16:39.000000000 +1100
> +++ linux-2.6/drivers/input/misc/pcspkr.c	2005-10-31 15:21:13.000000000 +1100
> @@ -66,6 +66,11 @@
>  
>  static int __init pcspkr_init(void)
>  {
> +#ifdef HAS_PCSPKR_ARCH_INIT
> +	int rc = pcspkr_arch_init();
> +	if (rc)
> +		return rc;
> +#endif
>  	pcspkr_dev = input_allocate_device();
>  	if (!pcspkr_dev)
>  		return -ENOMEM;
> Index: linux-2.6/include/asm-powerpc/8253pit.h
> ===================================================================
> --- linux-2.6.orig/include/asm-powerpc/8253pit.h	2005-10-31 15:02:18.000000000 +1100
> +++ linux-2.6/include/asm-powerpc/8253pit.h	2005-10-31 15:20:30.000000000 +1100
> @@ -5,6 +5,19 @@
>   * 8253/8254 Programmable Interval Timer
>   */
>  
> +#include <asm/prom.h>
> +
>  #define PIT_TICK_RATE	1193182UL
>  
> +#define HAS_PCSPKR_ARCH_INIT
> +
> +static inline int pcspkr_arch_init(void)
> +{
> +	struct device_node *np;
> +
> +	np = of_find_compatible_node(NULL, NULL, "pnpPNP,100");
> +	of_node_put(np);
> +	return np ? 0 : -ENODEV;
> +}
> +
>  #endif	/* _ASM_POWERPC_8253PIT_H */

We can avoid all the ifdef nasties by adding

static int pcspkr_arch_init(void) __attribute__((weak))
{
	return 0;
}

in pcspkr.c.

It'll bloat the kernel by a few bytes.

Re: [PATCH] Allow arch to veto PC speaker beeper initialization

[Paul Mackerras]

Andrew Morton writes:

> We can avoid all the ifdef nasties by adding
> 
> static int pcspkr_arch_init(void) __attribute__((weak))
> {
> 	return 0;
> }
> 
> in pcspkr.c.
> 
> It'll bloat the kernel by a few bytes.

I like it.  We'll do a new patch, if you haven't made the change
already yourself.

Paul.

Re: [PATCH] Allow arch to veto PC speaker beeper initialization

[Christoph Hellwig]

On Tue, Nov 15, 2005 at 01:02:00PM +1100, Paul Mackerras wrote:
> From: Michael Neuling <mikey@neuling.org>
> 
> This patch provides an arch hook in the PC speaker beeper driver which
> gives the arch code an opportunity to determine whether the machine
> has an i8253 timer or not.  If it doesn't we don't want the driver to
> go poking at the i8253's ports; there might be nothing there or there
> might be something else there which would be upset by being poked at.
> 
> We want to be able to build ppc64 kernels which work both on machines
> that have an i8253 equivalent (e.g. some pSeries) and on machines that
> don't (e.g. G5 powermacs), which is why we don't just remove it from
> the config.

Wrong way around.  The architecture should provide a way to find it, not
to veto it.  It should probably use the plattform_device infrastructure.