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>

5 files changed, 152 insertions, 0 deletions

diff --git a/arch/metag/include/asm/clock.h b/arch/metag/include/asm/clock.h
new file mode 100644
index 000000000000..3e2915a280c7
--- /dev/null
+++ b/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_ */
diff --git a/arch/metag/include/asm/delay.h b/arch/metag/include/asm/delay.h
new file mode 100644
index 000000000000..9c92f996957a
--- /dev/null
+++ b/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 */
diff --git a/arch/metag/include/asm/mach/arch.h b/arch/metag/include/asm/mach/arch.h
index 6845d80857e4..12c5664fea6e 100644
--- a/arch/metag/include/asm/mach/arch.h
+++ b/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;
 
diff --git a/arch/metag/kernel/clock.c b/arch/metag/kernel/clock.c
new file mode 100644
index 000000000000..defc84056f18
--- /dev/null
+++ b/arch/metag/kernel/clock.c
@@ -0,0 +1,53 @@
+/*
+ * arch/metag/kernel/clock.c
+ *
+ * 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.
+ */
+
+#include <linux/delay.h>
+#include <linux/io.h>
+
+#include <asm/param.h>
+#include <asm/clock.h>
+
+struct meta_clock_desc _meta_clock;
+
+/* Default machine get_core_freq callback. */
+static unsigned long get_core_freq_default(void)
+{
+#ifdef CONFIG_METAG_META21
+        /*
+         * Meta 2 cores divide down the core clock for the Meta timers, so we
+         * can estimate the core clock from the divider.
+         */
+        return (metag_in32(EXPAND_TIMER_DIV) + 1) * 1000000;
+#else
+        /*
+         * On Meta 1 we don't know the core clock, but assuming the Meta timer
+         * is correct it can be estimated based on loops_per_jiffy.
+         */
+        return (loops_per_jiffy * HZ * 5) >> 1;
+#endif
+}
+
+/**
+ * setup_meta_clocks() - Set up the Meta clock.
+ * @desc:       Clock descriptor usually provided by machine description
+ *
+ * Ensures all callbacks are valid.
+ */
+void __init setup_meta_clocks(struct meta_clock_desc *desc)
+{
+        /* copy callbacks */
+        if (desc)
+                _meta_clock = *desc;
+
+        /* set fallback functions */
+        if (!_meta_clock.get_core_freq)
+                _meta_clock.get_core_freq = get_core_freq_default;
+}
+
diff --git a/arch/metag/kernel/time.c b/arch/metag/kernel/time.c
new file mode 100644
index 000000000000..17dc10733b2f
--- /dev/null
+++ b/arch/metag/kernel/time.c
@@ -0,0 +1,15 @@
+/*
+ * Copyright (C) 2005-2013 Imagination Technologies Ltd.
+ *
+ * This file contains the Meta-specific time handling details.
+ *
+ */
+
+#include <linux/init.h>
+
+#include <clocksource/metag_generic.h>
+
+void __init time_init(void)
+{
+        metag_generic_timer_init();
+}