PNP: add CONFIG_PNP_DEBUG_MESSAGES and pnp_dbg()

This adds the core function pnp_dbg() and a new config option to
enable it.

The PNP core debugging messages can be enabled at boot-time with the
"pnp.debug" kernel parameter.
Signed-off-by: Bjorn Helgaas <bjorn.helgaas@hp.com>
Signed-off-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Len Brown <len.brown@intel.com>

Documentation/kernel-parameters.txt

@@ -1660,6 +1660,10 @@ and is between 256 and 4096 characters. It is defined in the file
 			Override pmtimer IOPort with a hex value.
 			e.g. pmtmr=0x508
 
+	pnp.debug	[PNP]
+			Enable PNP debug messages.  This depends on the
+			CONFIG_PNP_DEBUG_MESSAGES option.
+
 	pnpacpi=	[ACPI]
 			{ off }
 

drivers/pnp/Kconfig

@@ -20,6 +20,20 @@ menuconfig PNP
 
 	  If unsure, say Y.
 
+config PNP_DEBUG_MESSAGES
+	default y
+	bool "PNP debugging messages"
+	depends on PNP
+	help
+	  Say Y here if you want the PNP layer to be able to produce debugging
+	  messages if needed.  The messages can be enabled at boot-time with
+	  the pnp.debug kernel parameter.
+
+	  This option allows you to save a bit of space if you do not want
+	  the messages to even be built into the kernel.
+
+	  If you have any doubts about this, say Y here.
+
 if PNP
 
 config PNP_DEBUG

drivers/pnp/base.h

@@ -166,3 +166,13 @@ struct pnp_resource *pnp_add_io_resource(struct pnp_dev *dev,
 struct pnp_resource *pnp_add_mem_resource(struct pnp_dev *dev,
 					  resource_size_t start,
 					  resource_size_t end, int flags);
+
+extern int pnp_debug;
+
+#if defined(CONFIG_PNP_DEBUG_MESSAGES)
+#define pnp_dbg(dev, format, arg...)					\
+	({ if (pnp_debug) dev_printk(KERN_DEBUG, dev, format, ## arg); 0; })
+#else
+#define pnp_dbg(dev, format, arg...)					\
+	({ if (0) dev_printk(KERN_DEBUG, dev, format, ## arg); 0; })
+#endif

drivers/pnp/core.c

@@ -221,3 +221,14 @@ static int __init pnp_init(void)
 }
 
 subsys_initcall(pnp_init);
+
+int pnp_debug;
+
+#if defined(CONFIG_PNP_DEBUG_MESSAGES)
+static int __init pnp_debug_setup(char *__unused)
+{
+	pnp_debug = 1;
+	return 1;
+}
+__setup("pnp.debug", pnp_debug_setup);
+#endif