ARM: smp: remove arch-provided "pen_release"

Consolidating the "pen_release" stuff amongst the various SoC
implementations gives credence to having a CPU holding pen for
secondary CPUs.  However, this is far from the truth.

Many SoC implementations cargo-cult copied various bits of the pen
release implementation from the initial Realview/Versatile Express
implementation without understanding what it was or why it existed.
The reason it existed is because these are _development_ platforms,
and some board firmware is unable to individually control the
startup of secondary CPUs.  Moreover, they do not have a way to
power down or reset secondary CPUs for hot-unplug.  Hence, the
pen_release implementation was designed for ARM Ltd's development
platforms to provide a working implementation, even though it is
very far from what is required.

It was decided a while back to reduce the duplication by consolidating
the "pen_release" variable, but this only made the situation worse -
we have ended up with several implementations that read this variable
but do not write it - again, showing the cargo-cult mentality at work,
lack of proper review of new code, and in some cases a lack of testing.

While it would be preferable to remove pen_release entirely from the
kernel, this is not possible without help from the SoC maintainers,
which seems to be lacking.  However, I want to remove pen_release from
arch code to remove the credence that having it gives.

This patch removes pen_release from the arch code entirely, adding
private per-SoC definitions for it instead, and explicitly stating
that write_pen_release() is cargo-cult copied and should not be
copied any further.  Rename write_pen_release() in a similar fashion
as well.

Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>

arch/arm/mach-prima2/hotplug.c

@@ -11,6 +11,7 @@
 #include <linux/smp.h>
 
 #include <asm/smp_plat.h>
+#include "common.h"
 
 static inline void platform_do_lowpower(unsigned int cpu)
 {
@@ -18,7 +19,7 @@ static inline void platform_do_lowpower(unsigned int cpu)
 	for (;;) {
 		__asm__ __volatile__("dsb\n\t" "wfi\n\t"
 			: : : "memory");
-		if (pen_release == cpu_logical_map(cpu)) {
+		if (prima2_pen_release == cpu_logical_map(cpu)) {
 			/*
 			 * OK, proper wakeup, we're done
 			 */