src/kernel/linux/v4.19/arch/mips/sgi-ip27/ip27-timer.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copytight (C) 1999, 2000, 05, 06 Ralf Baechle (ralf@linux-mips.org)
 * Copytight (C) 1999, 2000 Silicon Graphics, Inc.
 */
#include <linux/bcd.h>
#include <linux/clockchips.h>
#include <linux/init.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/sched_clock.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/param.h>
#include <linux/smp.h>
#include <linux/time.h>
#include <linux/timex.h>
#include <linux/mm.h>
#include <linux/platform_device.h>

#include <asm/time.h>
#include <asm/pgtable.h>
#include <asm/sgialib.h>
#include <asm/sn/ioc3.h>
#include <asm/sn/klconfig.h>
#include <asm/sn/arch.h>
#include <asm/sn/addrs.h>
#include <asm/sn/sn_private.h>
#include <asm/sn/sn0/ip27.h>
#include <asm/sn/sn0/hub.h>

#define TICK_SIZE (tick_nsec / 1000)

/* Includes for ioc3_init().  */
#include <asm/sn/types.h>
#include <asm/sn/sn0/addrs.h>
#include <asm/sn/sn0/hubni.h>
#include <asm/sn/sn0/hubio.h>
#include <asm/pci/bridge.h>

static void enable_rt_irq(struct irq_data *d)
{
}

static void disable_rt_irq(struct irq_data *d)
{
}

static struct irq_chip rt_irq_type = {
	.name		= "SN HUB RT timer",
	.irq_mask	= disable_rt_irq,
	.irq_unmask	= enable_rt_irq,
};

static int rt_next_event(unsigned long delta, struct clock_event_device *evt)
{
	unsigned int cpu = smp_processor_id();
	int slice = cputoslice(cpu);
	unsigned long cnt;

	cnt = LOCAL_HUB_L(PI_RT_COUNT);
	cnt += delta;
	LOCAL_HUB_S(PI_RT_COMPARE_A + PI_COUNT_OFFSET * slice, cnt);

	return LOCAL_HUB_L(PI_RT_COUNT) >= cnt ? -ETIME : 0;
}

unsigned int rt_timer_irq;

static DEFINE_PER_CPU(struct clock_event_device, hub_rt_clockevent);
static DEFINE_PER_CPU(char [11], hub_rt_name);

static irqreturn_t hub_rt_counter_handler(int irq, void *dev_id)
{
	unsigned int cpu = smp_processor_id();
	struct clock_event_device *cd = &per_cpu(hub_rt_clockevent, cpu);
	int slice = cputoslice(cpu);

	/*
	 * Ack
	 */
	LOCAL_HUB_S(PI_RT_PEND_A + PI_COUNT_OFFSET * slice, 0);
	cd->event_handler(cd);

	return IRQ_HANDLED;
}

struct irqaction hub_rt_irqaction = {
	.handler	= hub_rt_counter_handler,
	.flags		= IRQF_PERCPU | IRQF_TIMER,
	.name		= "hub-rt",
};

/*
 * This is a hack; we really need to figure these values out dynamically
 *
 * Since 800 ns works very well with various HUB frequencies, such as
 * 360, 380, 390 and 400 MHZ, we use 800 ns rtc cycle time.
 *
 * Ralf: which clock rate is used to feed the counter?
 */
#define NSEC_PER_CYCLE		800
#define CYCLES_PER_SEC		(NSEC_PER_SEC / NSEC_PER_CYCLE)

void hub_rt_clock_event_init(void)
{
	unsigned int cpu = smp_processor_id();
	struct clock_event_device *cd = &per_cpu(hub_rt_clockevent, cpu);
	unsigned char *name = per_cpu(hub_rt_name, cpu);
	int irq = rt_timer_irq;

	sprintf(name, "hub-rt %d", cpu);
	cd->name		= name;
	cd->features		= CLOCK_EVT_FEAT_ONESHOT;
	clockevent_set_clock(cd, CYCLES_PER_SEC);
	cd->max_delta_ns	= clockevent_delta2ns(0xfffffffffffff, cd);
	cd->max_delta_ticks	= 0xfffffffffffff;
	cd->min_delta_ns	= clockevent_delta2ns(0x300, cd);
	cd->min_delta_ticks	= 0x300;
	cd->rating		= 200;
	cd->irq			= irq;
	cd->cpumask		= cpumask_of(cpu);
	cd->set_next_event	= rt_next_event;
	clockevents_register_device(cd);
}

static void __init hub_rt_clock_event_global_init(void)
{
	int irq;

	do {
		smp_wmb();
		irq = rt_timer_irq;
		if (irq)
			break;

		irq = allocate_irqno();
		if (irq < 0)
			panic("Allocation of irq number for timer failed");
	} while (xchg(&rt_timer_irq, irq));

	irq_set_chip_and_handler(irq, &rt_irq_type, handle_percpu_irq);
	setup_irq(irq, &hub_rt_irqaction);
}

static u64 hub_rt_read(struct clocksource *cs)
{
	return REMOTE_HUB_L(cputonasid(0), PI_RT_COUNT);
}

struct clocksource hub_rt_clocksource = {
	.name	= "HUB-RT",
	.rating = 200,
	.read	= hub_rt_read,
	.mask	= CLOCKSOURCE_MASK(52),
	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
};

static u64 notrace hub_rt_read_sched_clock(void)
{
	return REMOTE_HUB_L(cputonasid(0), PI_RT_COUNT);
}

static void __init hub_rt_clocksource_init(void)
{
	struct clocksource *cs = &hub_rt_clocksource;

	clocksource_register_hz(cs, CYCLES_PER_SEC);

	sched_clock_register(hub_rt_read_sched_clock, 52, CYCLES_PER_SEC);
}

void __init plat_time_init(void)
{
	hub_rt_clocksource_init();
	hub_rt_clock_event_global_init();
	hub_rt_clock_event_init();
}

void cpu_time_init(void)
{
	lboard_t *board;
	klcpu_t *cpu;
	int cpuid;

	/* Don't use ARCS.  ARCS is fragile.  Klconfig is simple and sane.  */
	board = find_lboard(KL_CONFIG_INFO(get_nasid()), KLTYPE_IP27);
	if (!board)
		panic("Can't find board info for myself.");

	cpuid = LOCAL_HUB_L(PI_CPU_NUM) ? IP27_CPU0_INDEX : IP27_CPU1_INDEX;
	cpu = (klcpu_t *) KLCF_COMP(board, cpuid);
	if (!cpu)
		panic("No information about myself?");

	printk("CPU %d clock is %dMHz.\n", smp_processor_id(), cpu->cpu_speed);

	set_c0_status(SRB_TIMOCLK);
}

void hub_rtc_init(cnodeid_t cnode)
{

	/*
	 * We only need to initialize the current node.
	 * If this is not the current node then it is a cpuless
	 * node and timeouts will not happen there.
	 */
	if (get_compact_nodeid() == cnode) {
		LOCAL_HUB_S(PI_RT_EN_A, 1);
		LOCAL_HUB_S(PI_RT_EN_B, 1);
		LOCAL_HUB_S(PI_PROF_EN_A, 0);
		LOCAL_HUB_S(PI_PROF_EN_B, 0);
		LOCAL_HUB_S(PI_RT_COUNT, 0);
		LOCAL_HUB_S(PI_RT_PEND_A, 0);
		LOCAL_HUB_S(PI_RT_PEND_B, 0);
	}
}

static int __init sgi_ip27_rtc_devinit(void)
{
	struct resource res;

	memset(&res, 0, sizeof(res));
	res.start = XPHYSADDR(KL_CONFIG_CH_CONS_INFO(master_nasid)->memory_base +
			      IOC3_BYTEBUS_DEV0);
	res.end = res.start + 32767;
	res.flags = IORESOURCE_MEM;

	return IS_ERR(platform_device_register_simple("rtc-m48t35", -1,
						      &res, 1));
}

/*
 * kludge make this a device_initcall after ioc3 resource conflicts
 * are resolved
 */
late_initcall(sgi_ip27_rtc_devinit);