MIPS: Alchemy: get rid of allow_au1k_wait

Eliminate the 'allow_au1k_wait' variable.  MIPS kernel installs the
Alchemy-specific wait code before timer initialization;  if the C0
timer must be used for timekeeping the wait function is set to NULL
which means no wait implementation is available.

As a sideeffect, the 'wait instruction available' output in
/proc/cpuinfo now correctly indicates whether 'wait' is usable.

Run-tested on DB1200.
Signed-off-by: NManuel Lauss <manuel.lauss@gmail.com>
Signed-off-by: NRalf Baechle <ralf@linux-mips.org>

arch/mips/alchemy/common/time.c

@@ -36,14 +36,13 @@
 #include <linux/interrupt.h>
 #include <linux/spinlock.h>
 
+#include <asm/processor.h>
 #include <asm/time.h>
 #include <asm/mach-au1x00/au1000.h>
 
 /* 32kHz clock enabled and detected */
 #define CNTR_OK (SYS_CNTRL_E0 | SYS_CNTRL_32S)
 
-extern int allow_au1k_wait; /* default off for CP0 Counter */
-
 static cycle_t au1x_counter1_read(struct clocksource *cs)
 {
 	return au_readl(SYS_RTCREAD);
@@ -153,13 +152,17 @@ void __init plat_time_init(void)
 
 	printk(KERN_INFO "Alchemy clocksource installed\n");
 
-	/* can now use 'wait' */
-	allow_au1k_wait = 1;
 	return;
 
 cntr_err:
-	/* counters unusable, use C0 counter */
+	/*
+	 * MIPS kernel assigns 'au1k_wait' to 'cpu_wait' before this
+	 * function is called.  Because the Alchemy counters are unusable
+	 * the C0 timekeeping code is installed and use of the 'wait'
+	 * instruction must be prohibited, which is done most easily by
+	 * assigning NULL to cpu_wait.
+	 */
+	cpu_wait = NULL;
 	r4k_clockevent_init();
 	init_r4k_clocksource();
-	allow_au1k_wait = 0;
 }

arch/mips/kernel/cpu-probe.c

@@ -91,16 +91,13 @@ static void rm7k_wait_irqoff(void)
 	local_irq_enable();
 }
 
-/* The Au1xxx wait is available only if using 32khz counter or
- * external timer source, but specifically not CP0 Counter. */
-int allow_au1k_wait;
-
+/*
+ * The Au1xxx wait is available only if using 32khz counter or
+ * external timer source, but specifically not CP0 Counter.
+ * alchemy/common/time.c may override cpu_wait!
+ */
 static void au1k_wait(void)
 {
-	if (!allow_au1k_wait)
-		return;
-
-	/* using the wait instruction makes CP0 counter unusable */
 	__asm__("	.set	mips3			\n"
 		"	cache	0x14, 0(%0)		\n"
 		"	cache	0x14, 32(%0)		\n"