diff options
author | Wu Zhangjin <wuzhangjin@gmail.com> | 2009-11-17 01:32:57 +0800 |
---|---|---|
committer | Ralf Baechle <ralf@linux-mips.org> | 2009-12-17 01:57:19 +0000 |
commit | 916daba8a9f2617ded8b9255e6b39f066ef60178 (patch) | |
tree | 63aa70b44e483bc30154130707e4d7529493543c /arch/mips/loongson/common/cs5536 | |
parent | 6e552c9b3aa7ba3be57b9569ec92a38af5c65e48 (diff) |
MIPS: Lemote 2F: Add cs5536 MFGPT timer support
CPUFreq support for Loongson 2F requires an external timer.
Because the frequency of the MIPS Timer is related to the CPU frequency
which itself is variable another timer of constant frequency is required.
Export the mfgpt0 counter disable / enable operations for the coming
suspend support to suspend / resume the timer.
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips@linux-mips.org
Cc: cpufreq@vger.kernel.org,
Cc: Dave Jones <davej@redhat.com>,
Cc: Dominik Brodowski <linux@dominikbrodowski.net>,
Cc: yanh@lemote.com
Cc: huhb@lemote.com,
Patchwork: http://patchwork.linux-mips.org/patch/658/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/loongson/common/cs5536')
-rw-r--r-- | arch/mips/loongson/common/cs5536/Makefile | 5 | ||||
-rw-r--r-- | arch/mips/loongson/common/cs5536/cs5536_mfgpt.c | 217 |
2 files changed, 222 insertions, 0 deletions
diff --git a/arch/mips/loongson/common/cs5536/Makefile b/arch/mips/loongson/common/cs5536/Makefile index 31657ee037d..510d4cdc237 100644 --- a/arch/mips/loongson/common/cs5536/Makefile +++ b/arch/mips/loongson/common/cs5536/Makefile @@ -5,4 +5,9 @@ obj-$(CONFIG_CS5536) += cs5536_pci.o cs5536_ide.o cs5536_acc.o cs5536_ohci.o \ cs5536_isa.o cs5536_ehci.o +# +# Enable cs5536 mfgpt Timer +# +obj-$(CONFIG_CS5536_MFGPT) += cs5536_mfgpt.o + EXTRA_CFLAGS += -Werror diff --git a/arch/mips/loongson/common/cs5536/cs5536_mfgpt.c b/arch/mips/loongson/common/cs5536/cs5536_mfgpt.c new file mode 100644 index 00000000000..6cb44dbaeec --- /dev/null +++ b/arch/mips/loongson/common/cs5536/cs5536_mfgpt.c @@ -0,0 +1,217 @@ +/* + * CS5536 General timer functions + * + * Copyright (C) 2007 Lemote Inc. & Insititute of Computing Technology + * Author: Yanhua, yanh@lemote.com + * + * Copyright (C) 2009 Lemote Inc. + * Author: Wu zhangjin, wuzj@lemote.com + * + * Reference: AMD Geode(TM) CS5536 Companion Device Data Book + * + * This program is free software; you can redistribute it and/or modify it + * under the terms of the GNU General Public License as published by the + * Free Software Foundation; either version 2 of the License, or (at your + * option) any later version. + */ + +#include <linux/io.h> +#include <linux/init.h> +#include <linux/module.h> +#include <linux/jiffies.h> +#include <linux/spinlock.h> +#include <linux/interrupt.h> +#include <linux/clockchips.h> + +#include <asm/time.h> + +#include <cs5536/cs5536_mfgpt.h> + +DEFINE_SPINLOCK(mfgpt_lock); +EXPORT_SYMBOL(mfgpt_lock); + +static u32 mfgpt_base; + +/* + * Initialize the MFGPT timer. + * + * This is also called after resume to bring the MFGPT into operation again. + */ + +/* disable counter */ +void disable_mfgpt0_counter(void) +{ + outw(inw(MFGPT0_SETUP) & 0x7fff, MFGPT0_SETUP); +} +EXPORT_SYMBOL(disable_mfgpt0_counter); + +/* enable counter, comparator2 to event mode, 14.318MHz clock */ +void enable_mfgpt0_counter(void) +{ + outw(0xe310, MFGPT0_SETUP); +} +EXPORT_SYMBOL(enable_mfgpt0_counter); + +static void init_mfgpt_timer(enum clock_event_mode mode, + struct clock_event_device *evt) +{ + spin_lock(&mfgpt_lock); + + switch (mode) { + case CLOCK_EVT_MODE_PERIODIC: + outw(COMPARE, MFGPT0_CMP2); /* set comparator2 */ + outw(0, MFGPT0_CNT); /* set counter to 0 */ + enable_mfgpt0_counter(); + break; + + case CLOCK_EVT_MODE_SHUTDOWN: + case CLOCK_EVT_MODE_UNUSED: + if (evt->mode == CLOCK_EVT_MODE_PERIODIC || + evt->mode == CLOCK_EVT_MODE_ONESHOT) + disable_mfgpt0_counter(); + break; + + case CLOCK_EVT_MODE_ONESHOT: + /* The oneshot mode have very high deviation, Not use it! */ + break; + + case CLOCK_EVT_MODE_RESUME: + /* Nothing to do here */ + break; + } + spin_unlock(&mfgpt_lock); +} + +static struct clock_event_device mfgpt_clockevent = { + .name = "mfgpt", + .features = CLOCK_EVT_FEAT_PERIODIC, + .set_mode = init_mfgpt_timer, + .irq = CS5536_MFGPT_INTR, +}; + +static irqreturn_t timer_interrupt(int irq, void *dev_id) +{ + u32 basehi; + + /* + * get MFGPT base address + * + * NOTE: do not remove me, it's need for the value of mfgpt_base is + * variable + */ + _rdmsr(DIVIL_MSR_REG(DIVIL_LBAR_MFGPT), &basehi, &mfgpt_base); + + /* ack */ + outw(inw(MFGPT0_SETUP) | 0x4000, MFGPT0_SETUP); + + mfgpt_clockevent.event_handler(&mfgpt_clockevent); + + return IRQ_HANDLED; +} + +static struct irqaction irq5 = { + .handler = timer_interrupt, + .flags = IRQF_DISABLED | IRQF_NOBALANCING | IRQF_TIMER, + .name = "timer" +}; + +/* + * Initialize the conversion factor and the min/max deltas of the clock event + * structure and register the clock event source with the framework. + */ +void __init setup_mfgpt0_timer(void) +{ + u32 basehi; + struct clock_event_device *cd = &mfgpt_clockevent; + unsigned int cpu = smp_processor_id(); + + cd->cpumask = cpumask_of(cpu); + clockevent_set_clock(cd, MFGPT_TICK_RATE); + cd->max_delta_ns = clockevent_delta2ns(0xffff, cd); + cd->min_delta_ns = clockevent_delta2ns(0xf, cd); + + /* Enable MFGPT0 Comparator 2 Output to the Interrupt Mapper */ + _wrmsr(DIVIL_MSR_REG(MFGPT_IRQ), 0, 0x100); + + /* Enable Interrupt Gate 5 */ + _wrmsr(DIVIL_MSR_REG(PIC_ZSEL_LOW), 0, 0x50000); + + /* get MFGPT base address */ + _rdmsr(DIVIL_MSR_REG(DIVIL_LBAR_MFGPT), &basehi, &mfgpt_base); + + clockevents_register_device(cd); + + setup_irq(CS5536_MFGPT_INTR, &irq5); +} + +/* + * Since the MFGPT overflows every tick, its not very useful + * to just read by itself. So use jiffies to emulate a free + * running counter: + */ +static cycle_t mfgpt_read(struct clocksource *cs) +{ + unsigned long flags; + int count; + u32 jifs; + static int old_count; + static u32 old_jifs; + + spin_lock_irqsave(&mfgpt_lock, flags); + /* + * Although our caller may have the read side of xtime_lock, + * this is now a seqlock, and we are cheating in this routine + * by having side effects on state that we cannot undo if + * there is a collision on the seqlock and our caller has to + * retry. (Namely, old_jifs and old_count.) So we must treat + * jiffies as volatile despite the lock. We read jiffies + * before latching the timer count to guarantee that although + * the jiffies value might be older than the count (that is, + * the counter may underflow between the last point where + * jiffies was incremented and the point where we latch the + * count), it cannot be newer. + */ + jifs = jiffies; + /* read the count */ + count = inw(MFGPT0_CNT); + + /* + * It's possible for count to appear to go the wrong way for this + * reason: + * + * The timer counter underflows, but we haven't handled the resulting + * interrupt and incremented jiffies yet. + * + * Previous attempts to handle these cases intelligently were buggy, so + * we just do the simple thing now. + */ + if (count < old_count && jifs == old_jifs) + count = old_count; + + old_count = count; + old_jifs = jifs; + + spin_unlock_irqrestore(&mfgpt_lock, flags); + + return (cycle_t) (jifs * COMPARE) + count; +} + +static struct clocksource clocksource_mfgpt = { + .name = "mfgpt", + .rating = 120, /* Functional for real use, but not desired */ + .read = mfgpt_read, + .mask = CLOCKSOURCE_MASK(32), + .mult = 0, + .shift = 22, +}; + +int __init init_mfgpt_clocksource(void) +{ + if (num_possible_cpus() > 1) /* MFGPT does not scale! */ + return 0; + + clocksource_mfgpt.mult = clocksource_hz2mult(MFGPT_TICK_RATE, 22); + return clocksource_register(&clocksource_mfgpt); +} + +arch_initcall(init_mfgpt_clocksource); |