Release 4.11 drivers/clocksource/metag_generic.c
/*
* Copyright (C) 2005-2013 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.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*
*
* Support for Meta per-thread timers.
*
* Meta hardware threads have 2 timers. The background timer (TXTIMER) is used
* as a free-running time base (hz clocksource), and the interrupt timer
* (TXTIMERI) is used for the timer interrupt (clock event). Both counters
* traditionally count at approximately 1MHz.
*/
#include <clocksource/metag_generic.h>
#include <linux/cpu.h>
#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;
}
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static u64 metag_clocksource_read(struct clocksource *cs)
{
return __core_reg_get(TXTIMER);
}
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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 = this_cpu_ptr(&local_clockevent);
evt->event_handler(evt);
return IRQ_HANDLED;
}
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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 = __core_reg_get(TXTIMER);
return ticks << HARDWARE_TO_NS_SHIFT;
}
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static int arch_timer_starting_cpu(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_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);
__core_reg_set(TXTIMER, val);
}
return 0;
}
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int __init metag_generic_timer_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
pr_info("Timer frequency: %u Hz\n", hwtimer_freq);
clocksource_register_hz(&clocksource_metag, hwtimer_freq);
setup_irq(tbisig_map(TBID_SIGNUM_TRT), &metag_timer_irq);
/* Hook cpu boot to configure the CPU's timers */
return cpuhp_setup_state(CPUHP_AP_METAG_TIMER_STARTING,
"clockevents/metag:starting",
arch_timer_starting_cpu, NULL);
}
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