cregit-Linux how code gets into the kernel

Release 4.7 drivers/clocksource/mips-gic-timer.c

/*
 * This file is subject to the terms and conditions of the GNU General Public
 * License.  See the file "COPYING" in the main directory of this archive
 * for more details.
 *
 * Copyright (C) 2012 MIPS Technologies, Inc.  All rights reserved.
 */
#include <linux/clk.h>
#include <linux/clockchips.h>
#include <linux/cpu.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/irqchip/mips-gic.h>
#include <linux/notifier.h>
#include <linux/of_irq.h>
#include <linux/percpu.h>
#include <linux/smp.h>
#include <linux/time.h>

static DEFINE_PER_CPU(struct clock_event_device, gic_clockevent_device);

static int gic_timer_irq;

static unsigned int gic_frequency;


static int gic_next_event(unsigned long delta, struct clock_event_device *evt) { u64 cnt; int res; cnt = gic_read_count(); cnt += (u64)delta; gic_write_cpu_compare(cnt, cpumask_first(evt->cpumask)); res = ((int)(gic_read_count() - cnt) >= 0) ? -ETIME : 0; return res; }

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static irqreturn_t gic_compare_interrupt(int irq, void *dev_id) { struct clock_event_device *cd = dev_id; gic_write_compare(gic_read_compare()); cd->event_handler(cd); return IRQ_HANDLED; }

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struct irqaction gic_compare_irqaction = { .handler = gic_compare_interrupt, .percpu_dev_id = &gic_clockevent_device, .flags = IRQF_PERCPU | IRQF_TIMER, .name = "timer", };
static void gic_clockevent_cpu_init(struct clock_event_device *cd) { unsigned int cpu = smp_processor_id(); cd->name = "MIPS GIC"; cd->features = CLOCK_EVT_FEAT_ONESHOT | CLOCK_EVT_FEAT_C3STOP; cd->rating = 350; cd->irq = gic_timer_irq; cd->cpumask = cpumask_of(cpu); cd->set_next_event = gic_next_event; clockevents_config_and_register(cd, gic_frequency, 0x300, 0x7fffffff); enable_percpu_irq(gic_timer_irq, IRQ_TYPE_NONE); }

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static void gic_clockevent_cpu_exit(struct clock_event_device *cd) { disable_percpu_irq(gic_timer_irq); }

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static void gic_update_frequency(void *data) { unsigned long rate = (unsigned long)data; clockevents_update_freq(this_cpu_ptr(&gic_clockevent_device), rate); }

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static int gic_cpu_notifier(struct notifier_block *nb, unsigned long action, void *data) { switch (action & ~CPU_TASKS_FROZEN) { case CPU_STARTING: gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device)); break; case CPU_DYING: gic_clockevent_cpu_exit(this_cpu_ptr(&gic_clockevent_device)); break; } return NOTIFY_OK; }

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static int gic_clk_notifier(struct notifier_block *nb, unsigned long action, void *data) { struct clk_notifier_data *cnd = data; if (action == POST_RATE_CHANGE) on_each_cpu(gic_update_frequency, (void *)cnd->new_rate, 1); return NOTIFY_OK; }

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static struct notifier_block gic_cpu_nb = { .notifier_call = gic_cpu_notifier, }; static struct notifier_block gic_clk_nb = { .notifier_call = gic_clk_notifier, };
static int gic_clockevent_init(void) { int ret; if (!cpu_has_counter || !gic_frequency) return -ENXIO; ret = setup_percpu_irq(gic_timer_irq, &gic_compare_irqaction); if (ret < 0) return ret; ret = register_cpu_notifier(&gic_cpu_nb); if (ret < 0) pr_warn("GIC: Unable to register CPU notifier\n"); gic_clockevent_cpu_init(this_cpu_ptr(&gic_clockevent_device)); return 0; }

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static cycle_t gic_hpt_read(struct clocksource *cs) { return gic_read_count(); }

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static struct clocksource gic_clocksource = { .name = "GIC", .read = gic_hpt_read, .flags = CLOCK_SOURCE_IS_CONTINUOUS, .archdata = { .vdso_clock_mode = VDSO_CLOCK_GIC }, };
static void __init __gic_clocksource_init(void) { int ret; /* Set clocksource mask. */ gic_clocksource.mask = CLOCKSOURCE_MASK(gic_get_count_width()); /* Calculate a somewhat reasonable rating value. */ gic_clocksource.rating = 200 + gic_frequency / 10000000; ret = clocksource_register_hz(&gic_clocksource, gic_frequency); if (ret < 0) pr_warn("GIC: Unable to register clocksource\n"); }

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void __init gic_clocksource_init(unsigned int frequency) { gic_frequency = frequency; gic_timer_irq = MIPS_GIC_IRQ_BASE + GIC_LOCAL_TO_HWIRQ(GIC_LOCAL_INT_COMPARE); __gic_clocksource_init(); gic_clockevent_init(); /* And finally start the counter */ gic_start_count(); }

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static void __init gic_clocksource_of_init(struct device_node *node) { struct clk *clk; int ret; if (WARN_ON(!gic_present || !node->parent || !of_device_is_compatible(node->parent, "mti,gic"))) return; clk = of_clk_get(node, 0); if (!IS_ERR(clk)) { if (clk_prepare_enable(clk) < 0) { pr_err("GIC failed to enable clock\n"); clk_put(clk); return; } gic_frequency = clk_get_rate(clk); } else if (of_property_read_u32(node, "clock-frequency", &gic_frequency)) { pr_err("GIC frequency not specified.\n"); return; } gic_timer_irq = irq_of_parse_and_map(node, 0); if (!gic_timer_irq) { pr_err("GIC timer IRQ not specified.\n"); return; } __gic_clocksource_init(); ret = gic_clockevent_init(); if (!ret && !IS_ERR(clk)) { if (clk_notifier_register(clk, &gic_clk_nb) < 0) pr_warn("GIC: Unable to register clock notifier\n"); } /* And finally start the counter */ gic_start_count(); }

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CLOCKSOURCE_OF_DECLARE(mips_gic_timer, "mti,gic-timer", gic_clocksource_of_init);

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alex smithalex smith101.20%15.26%
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