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>
diff --git a/drivers/pnp/base.h b/drivers/pnp/base.h
index 9fd7bb9..5e4e82c 100644
--- a/drivers/pnp/base.h
+++ b/drivers/pnp/base.h
@@ -166,3 +166,13 @@
 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