AT91: fix use of clock disable on idle for AT91x40 devices

The simpler AT91x40 processors do not have the same power management
controller as the new AT91 devices. They do have a simpler power
controller module that we can use to disable the CPU clock at idle
time. Add code to support that.

Signed-off-by: Greg Ungerer <gerg@uclinux.org>
Acked-by: Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>
Acked-by: Nicolas Ferre <nicolas.ferre@atmel.com>

arch/arm/mach-at91/include/mach/at91x40.h

@@ -52,4 +52,10 @@
 #define AT91_DBGU_CIDR	(AT91_SF + 0)	/* CIDR in PS segment */
 #define AT91_DBGU_EXID	(AT91_SF + 4)	/* EXID in PS segment */
 
+/*
+ * Support defines for the simple Power Controller module.
+ */
+#define	AT91_PS_CR	(AT91_PS + 0)	/* PS Control register */
+#define	AT91_PS_CR_CPU	(1 << 0)	/* CPU clock disable bit */
+
 #endif /* AT91X40_H */

arch/arm/mach-at91/include/mach/system.h

@@ -33,7 +33,11 @@ static inline void arch_idle(void)
 	 * Disable the processor clock.  The processor will be automatically
 	 * re-enabled by an interrupt or by a reset.
 	 */
+#ifdef AT91_PS
+	at91_sys_write(AT91_PS_CR, AT91_PS_CR_CPU);
+#else
 	at91_sys_write(AT91_PMC_SCDR, AT91_PMC_PCK);
+#endif
 #else
 	/*
 	 * Set the processor (CP15) into 'Wait for Interrupt' mode.