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Subject[PATCH v3 21/44] metag: Time keeping
Date
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>
---
arch/metag/include/asm/clock.h | 51 +++++++++++
arch/metag/include/asm/delay.h | 29 +++++++
arch/metag/include/asm/mach/arch.h | 4 +
arch/metag/kernel/clock.c | 53 ++++++++++++
arch/metag/kernel/time.c | 163 ++++++++++++++++++++++++++++++++++++
5 files changed, 300 insertions(+), 0 deletions(-)
create mode 100644 arch/metag/include/asm/clock.h
create mode 100644 arch/metag/include/asm/delay.h
create mode 100644 arch/metag/kernel/clock.c
create mode 100644 arch/metag/kernel/time.c

diff --git a/arch/metag/include/asm/clock.h b/arch/metag/include/asm/clock.h
new file mode 100644
index 0000000..3e2915a
--- /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 0000000..9c92f99
--- /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 6845d80..12c5664 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 0000000..defc840
--- /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 0000000..40c2f4a
--- /dev/null
+++ b/arch/metag/kernel/time.c
@@ -0,0 +1,163 @@
+/*
+ * Copyright (C) 2005,2006,2007,2008 Imagination Technologies Ltd.
+ *
+ * This file contains the Meta-specific time handling details.
+ *
+ */
+
+#include <linux/errno.h>
+#include <linux/sched.h>
+#include <linux/kernel.h>
+#include <linux/param.h>
+#include <linux/time.h>
+#include <linux/init.h>
+#include <linux/proc_fs.h>
+#include <linux/clocksource.h>
+#include <linux/clockchips.h>
+#include <linux/interrupt.h>
+
+#include <asm/clock.h>
+#include <asm/hwthread.h>
+#include <asm/core_reg.h>
+#include <asm/metag_mem.h>
+#include <asm/tbx.h>
+
+#define HARDWARE_FREQ 1000000 /* 1MHz */
+#define HARDWARE_DIV 1 /* divide by 1 = 1MHz clock */
+#define HARDWARE_TO_NS_SHIFT 10 /* convert ticks to ns */
+
+static unsigned int hwtimer_freq = HARDWARE_FREQ;
+static DEFINE_PER_CPU(struct clock_event_device, local_clockevent);
+static DEFINE_PER_CPU(char [11], local_clockevent_name);
+
+static int metag_timer_set_next_event(unsigned long delta,
+ struct clock_event_device *dev)
+{
+ __core_reg_set(TXTIMERI, -delta);
+ return 0;
+}
+
+static void metag_timer_set_mode(enum clock_event_mode mode,
+ struct clock_event_device *evt)
+{
+ switch (mode) {
+ case CLOCK_EVT_MODE_ONESHOT:
+ case CLOCK_EVT_MODE_RESUME:
+ break;
+
+ case CLOCK_EVT_MODE_SHUTDOWN:
+ /* We should disable the IRQ here */
+ break;
+
+ case CLOCK_EVT_MODE_PERIODIC:
+ case CLOCK_EVT_MODE_UNUSED:
+ WARN_ON(1);
+ break;
+ };
+}
+
+static inline cycle_t txtimer_read(void)
+{
+ unsigned int ret;
+
+ asm volatile ("MOV %0, TXTIMER\n" : "=r" (ret));
+ return ret;
+}
+
+static cycle_t metag_clocksource_read(struct clocksource *cs)
+{
+ return txtimer_read();
+}
+
+static struct clocksource clocksource_metag = {
+ .name = "META",
+ .rating = 200,
+ .mask = CLOCKSOURCE_MASK(32),
+ .read = metag_clocksource_read,
+ .flags = CLOCK_SOURCE_IS_CONTINUOUS,
+};
+
+static irqreturn_t metag_timer_interrupt(int irq, void *dummy)
+{
+ struct clock_event_device *evt = &__get_cpu_var(local_clockevent);
+
+ evt->event_handler(evt);
+
+ return IRQ_HANDLED;
+}
+
+static struct irqaction metag_timer_irq = {
+ .name = "META core timer",
+ .handler = metag_timer_interrupt,
+ .flags = IRQF_TIMER | IRQF_IRQPOLL | IRQF_PERCPU,
+};
+
+unsigned long long sched_clock(void)
+{
+ unsigned long long ticks = txtimer_read();
+ return ticks << HARDWARE_TO_NS_SHIFT;
+}
+
+void __cpuinit local_timer_setup(unsigned int cpu)
+{
+ unsigned int txdivtime;
+ struct clock_event_device *clk = &per_cpu(local_clockevent, cpu);
+ char *name = per_cpu(local_clockevent_name, cpu);
+
+ txdivtime = __core_reg_get(TXDIVTIME);
+
+ txdivtime &= ~TXDIVTIME_DIV_BITS;
+ txdivtime |= (HARDWARE_DIV & TXDIVTIME_DIV_BITS);
+
+ __core_reg_set(TXDIVTIME, txdivtime);
+
+ sprintf(name, "META %d", cpu);
+ clk->name = name;
+ clk->features = CLOCK_EVT_FEAT_ONESHOT,
+
+ clk->rating = 200,
+ clk->shift = 12,
+ clk->irq = tbisig_map(TBID_SIGNUM_TRT),
+ clk->set_mode = metag_timer_set_mode,
+ clk->set_next_event = metag_timer_set_next_event,
+
+ clk->mult = div_sc(hwtimer_freq, NSEC_PER_SEC, clk->shift);
+ clk->max_delta_ns = clockevent_delta2ns(0x7fffffff, clk);
+ clk->min_delta_ns = clockevent_delta2ns(0xf, clk);
+ clk->cpumask = cpumask_of(cpu);
+
+ clockevents_register_device(clk);
+
+ /*
+ * For all non-boot CPUs we need to synchronize our free
+ * running clock (TXTIMER) with the boot CPU's clock.
+ *
+ * While this won't be accurate, it should be close enough.
+ */
+ if (cpu) {
+ unsigned int thread0 = cpu_2_hwthread_id[0];
+ unsigned long val;
+
+ val = core_reg_read(TXUCT_ID, TXTIMER_REGNUM, thread0);
+
+ asm volatile ("MOV TXTIMER, %0\n" : : "r" (val));
+ }
+}
+
+void __init time_init(void)
+{
+ /*
+ * On Meta 2 SoCs, the actual frequency of the timer is based on the
+ * Meta core clock speed divided by an integer, so it is only
+ * approximately 1MHz. Calculating the real frequency here drastically
+ * reduces clock skew on these SoCs.
+ */
+#ifdef CONFIG_METAG_META21
+ hwtimer_freq = get_coreclock() / (metag_in32(EXPAND_TIMER_DIV) + 1);
+#endif
+ clocksource_register_hz(&clocksource_metag, hwtimer_freq);
+
+ setup_irq(tbisig_map(TBID_SIGNUM_TRT), &metag_timer_irq);
+
+ local_timer_setup(smp_processor_id());
+}
--
1.7.7.6



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