diff options
Diffstat (limited to 'arch/mips/loongson2ef/common/cs5536/cs5536_mfgpt.c')
| -rw-r--r-- | arch/mips/loongson2ef/common/cs5536/cs5536_mfgpt.c | 207 |
1 files changed, 207 insertions, 0 deletions
diff --git a/arch/mips/loongson2ef/common/cs5536/cs5536_mfgpt.c b/arch/mips/loongson2ef/common/cs5536/cs5536_mfgpt.c new file mode 100644 index 000000000000..30af1b7c7529 --- /dev/null +++ b/arch/mips/loongson2ef/common/cs5536/cs5536_mfgpt.c @@ -0,0 +1,207 @@ +// SPDX-License-Identifier: GPL-2.0-or-later +/* + * CS5536 General timer functions + * + * Copyright (C) 2007 Lemote Inc. & Institute of Computing Technology + * Author: Yanhua, yanh@lemote.com + * + * Copyright (C) 2009 Lemote Inc. + * Author: Wu zhangjin, wuzhangjin@gmail.com + * + * Reference: AMD Geode(TM) CS5536 Companion Device Data Book + */ + +#include <linux/io.h> +#include <linux/init.h> +#include <linux/export.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> + +static DEFINE_RAW_SPINLOCK(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 int mfgpt_timer_set_periodic(struct clock_event_device *evt) +{ + raw_spin_lock(&mfgpt_lock); + + outw(COMPARE, MFGPT0_CMP2); /* set comparator2 */ + outw(0, MFGPT0_CNT); /* set counter to 0 */ + enable_mfgpt0_counter(); + + raw_spin_unlock(&mfgpt_lock); + return 0; +} + +static int mfgpt_timer_shutdown(struct clock_event_device *evt) +{ + if (clockevent_state_periodic(evt) || clockevent_state_oneshot(evt)) { + raw_spin_lock(&mfgpt_lock); + disable_mfgpt0_counter(); + raw_spin_unlock(&mfgpt_lock); + } + + return 0; +} + +static struct clock_event_device mfgpt_clockevent = { + .name = "mfgpt", + .features = CLOCK_EVT_FEAT_PERIODIC, + + /* The oneshot mode have very high deviation, don't use it! */ + .set_state_shutdown = mfgpt_timer_shutdown, + .set_state_periodic = mfgpt_timer_set_periodic, + .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_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->max_delta_ticks = 0xffff; + cd->min_delta_ns = clockevent_delta2ns(0xf, cd); + cd->min_delta_ticks = 0xf; + + /* 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 u64 mfgpt_read(struct clocksource *cs) +{ + unsigned long flags; + int count; + u32 jifs; + static int old_count; + static u32 old_jifs; + + raw_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; + + raw_spin_unlock_irqrestore(&mfgpt_lock, flags); + + return (u64) (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), +}; + +int __init init_mfgpt_clocksource(void) +{ + if (num_possible_cpus() > 1) /* MFGPT does not scale! */ + return 0; + + return clocksource_register_hz(&clocksource_mfgpt, MFGPT_TICK_RATE); +} + +arch_initcall(init_mfgpt_clocksource); |