metag: Time keeping

Add time keeping code for metag. Meta hardware threads have 2 timers.
The background timer (TXTIMER) is used as a free-running time base, and
the interrupt timer (TXTIMERI) is used for the timer interrupt. Both
counters traditionally count at approximately 1MHz.

Signed-off-by: James Hogan <james.hogan@imgtec.com>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>

arch/metag/include/asm/clock.h

@@ -0,0 +1,51 @@
+/*
+ * arch/metag/include/asm/clock.h
+ *
+ * Copyright (C) 2012 Imagination Technologies Ltd.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation.
+ */
+
+#ifndef _METAG_CLOCK_H_
+#define _METAG_CLOCK_H_
+
+#include <asm/mach/arch.h>
+
+/**
+ * struct meta_clock_desc - Meta Core clock callbacks.
+ * @get_core_freq:	Get the frequency of the Meta core. If this is NULL, the
+ *			core frequency will be determined like this:
+ *			Meta 1: based on loops_per_jiffy.
+ *			Meta 2: (EXPAND_TIMER_DIV + 1) MHz.
+ */
+struct meta_clock_desc {
+	unsigned long		(*get_core_freq)(void);
+};
+
+extern struct meta_clock_desc _meta_clock;
+
+/*
+ * Set up the default clock, ensuring all callbacks are valid - only accessible
+ * during boot.
+ */
+void setup_meta_clocks(struct meta_clock_desc *desc);
+
+/**
+ * get_coreclock() - Get the frequency of the Meta core clock.
+ *
+ * Returns:	The Meta core clock frequency in Hz.
+ */
+static inline unsigned long get_coreclock(void)
+{
+	/*
+	 * Use the current clock callback. If set correctly this will provide
+	 * the most accurate frequency as it can be calculated directly from the
+	 * PLL configuration. otherwise a default callback will have been set
+	 * instead.
+	 */
+	return _meta_clock.get_core_freq();
+}
+
+#endif /* _METAG_CLOCK_H_ */

arch/metag/include/asm/delay.h

@@ -0,0 +1,29 @@
+#ifndef _METAG_DELAY_H
+#define _METAG_DELAY_H
+
+/*
+ * Copyright (C) 1993 Linus Torvalds
+ *
+ * Delay routines calling functions in arch/metag/lib/delay.c
+ */
+
+/* Undefined functions to get compile-time errors */
+extern void __bad_udelay(void);
+extern void __bad_ndelay(void);
+
+extern void __udelay(unsigned long usecs);
+extern void __ndelay(unsigned long nsecs);
+extern void __const_udelay(unsigned long xloops);
+extern void __delay(unsigned long loops);
+
+/* 0x10c7 is 2**32 / 1000000 (rounded up) */
+#define udelay(n) (__builtin_constant_p(n) ? \
+	((n) > 20000 ? __bad_udelay() : __const_udelay((n) * 0x10c7ul)) : \
+	__udelay(n))
+
+/* 0x5 is 2**32 / 1000000000 (rounded up) */
+#define ndelay(n) (__builtin_constant_p(n) ? \
+	((n) > 20000 ? __bad_ndelay() : __const_udelay((n) * 5ul)) : \
+	__ndelay(n))
+
+#endif /* _METAG_DELAY_H */

arch/metag/include/asm/mach/arch.h

@@ -16,10 +16,13 @@
 
 #include <linux/stddef.h>
 
+#include <asm/clock.h>
+
 /**
  * struct machine_desc - Describes a board controlled by a Meta.
  * @name:		Board/SoC name.
  * @dt_compat:		Array of device tree 'compatible' strings.
+ * @clocks:		Clock callbacks.
  *
  * @nr_irqs:		Maximum number of IRQs.
  *			If 0, defaults to NR_IRQS in asm-generic/irq.h.
@@ -37,6 +40,7 @@
 struct machine_desc {
 	const char		*name;
 	const char		**dt_compat;
+	struct meta_clock_desc	*clocks;
 
 	unsigned int		nr_irqs;