cregit-Linux how code gets into the kernel

Release 4.7 drivers/clocksource/timer-atlas7.c

/*
 * System timer for CSR SiRFprimaII
 *
 * Copyright (c) 2011 Cambridge Silicon Radio Limited, a CSR plc group company.
 *
 * Licensed under GPLv2 or later.
 */

#include <linux/kernel.h>
#include <linux/interrupt.h>
#include <linux/clockchips.h>
#include <linux/clocksource.h>
#include <linux/cpu.h>
#include <linux/bitops.h>
#include <linux/irq.h>
#include <linux/clk.h>
#include <linux/slab.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <linux/sched_clock.h>


#define SIRFSOC_TIMER_32COUNTER_0_CTRL			0x0000

#define SIRFSOC_TIMER_32COUNTER_1_CTRL			0x0004

#define SIRFSOC_TIMER_MATCH_0				0x0018

#define SIRFSOC_TIMER_MATCH_1				0x001c

#define SIRFSOC_TIMER_COUNTER_0				0x0048

#define SIRFSOC_TIMER_COUNTER_1				0x004c

#define SIRFSOC_TIMER_INTR_STATUS			0x0060

#define SIRFSOC_TIMER_WATCHDOG_EN			0x0064

#define SIRFSOC_TIMER_64COUNTER_CTRL			0x0068

#define SIRFSOC_TIMER_64COUNTER_LO			0x006c

#define SIRFSOC_TIMER_64COUNTER_HI			0x0070

#define SIRFSOC_TIMER_64COUNTER_LOAD_LO			0x0074

#define SIRFSOC_TIMER_64COUNTER_LOAD_HI			0x0078

#define SIRFSOC_TIMER_64COUNTER_RLATCHED_LO		0x007c

#define SIRFSOC_TIMER_64COUNTER_RLATCHED_HI		0x0080


#define SIRFSOC_TIMER_REG_CNT 6


static unsigned long atlas7_timer_rate;


static const u32 sirfsoc_timer_reg_list[SIRFSOC_TIMER_REG_CNT] = {
	SIRFSOC_TIMER_WATCHDOG_EN,
	SIRFSOC_TIMER_32COUNTER_0_CTRL,
	SIRFSOC_TIMER_32COUNTER_1_CTRL,
	SIRFSOC_TIMER_64COUNTER_CTRL,
	SIRFSOC_TIMER_64COUNTER_RLATCHED_LO,
	SIRFSOC_TIMER_64COUNTER_RLATCHED_HI,
};


static u32 sirfsoc_timer_reg_val[SIRFSOC_TIMER_REG_CNT];


static void __iomem *sirfsoc_timer_base;

/* disable count and interrupt */

static inline void sirfsoc_timer_count_disable(int idx) { writel_relaxed(readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_32COUNTER_0_CTRL + 4 * idx) & ~0x7, sirfsoc_timer_base + SIRFSOC_TIMER_32COUNTER_0_CTRL + 4 * idx); }

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/* enable count and interrupt */
static inline void sirfsoc_timer_count_enable(int idx) { writel_relaxed(readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_32COUNTER_0_CTRL + 4 * idx) | 0x3, sirfsoc_timer_base + SIRFSOC_TIMER_32COUNTER_0_CTRL + 4 * idx); }

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/* timer interrupt handler */
static irqreturn_t sirfsoc_timer_interrupt(int irq, void *dev_id) { struct clock_event_device *ce = dev_id; int cpu = smp_processor_id(); /* clear timer interrupt */ writel_relaxed(BIT(cpu), sirfsoc_timer_base + SIRFSOC_TIMER_INTR_STATUS); if (clockevent_state_oneshot(ce)) sirfsoc_timer_count_disable(cpu); ce->event_handler(ce); return IRQ_HANDLED; }

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/* read 64-bit timer counter */
static cycle_t sirfsoc_timer_read(struct clocksource *cs) { u64 cycles; writel_relaxed((readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_CTRL) | BIT(0)) & ~BIT(1), sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_CTRL); cycles = readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_RLATCHED_HI); cycles = (cycles << 32) | readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_RLATCHED_LO); return cycles; }

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static int sirfsoc_timer_set_next_event(unsigned long delta, struct clock_event_device *ce) { int cpu = smp_processor_id(); /* disable timer first, then modify the related registers */ sirfsoc_timer_count_disable(cpu); writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_0 + 4 * cpu); writel_relaxed(delta, sirfsoc_timer_base + SIRFSOC_TIMER_MATCH_0 + 4 * cpu); /* enable the tick */ sirfsoc_timer_count_enable(cpu); return 0; }

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/* Oneshot is enabled in set_next_event */
static int sirfsoc_timer_shutdown(struct clock_event_device *evt) { sirfsoc_timer_count_disable(smp_processor_id()); return 0; }

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static void sirfsoc_clocksource_suspend(struct clocksource *cs) { int i; for (i = 0; i < SIRFSOC_TIMER_REG_CNT; i++) sirfsoc_timer_reg_val[i] = readl_relaxed(sirfsoc_timer_base + sirfsoc_timer_reg_list[i]); }

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static void sirfsoc_clocksource_resume(struct clocksource *cs) { int i; for (i = 0; i < SIRFSOC_TIMER_REG_CNT - 2; i++) writel_relaxed(sirfsoc_timer_reg_val[i], sirfsoc_timer_base + sirfsoc_timer_reg_list[i]); writel_relaxed(sirfsoc_timer_reg_val[SIRFSOC_TIMER_REG_CNT - 2], sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_LOAD_LO); writel_relaxed(sirfsoc_timer_reg_val[SIRFSOC_TIMER_REG_CNT - 1], sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_LOAD_HI); writel_relaxed(readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_CTRL) | BIT(1) | BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_CTRL); }

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static struct clock_event_device __percpu *sirfsoc_clockevent; static struct clocksource sirfsoc_clocksource = { .name = "sirfsoc_clocksource", .rating = 200, .mask = CLOCKSOURCE_MASK(64), .flags = CLOCK_SOURCE_IS_CONTINUOUS, .read = sirfsoc_timer_read, .suspend = sirfsoc_clocksource_suspend, .resume = sirfsoc_clocksource_resume, }; static struct irqaction sirfsoc_timer_irq = { .name = "sirfsoc_timer0", .flags = IRQF_TIMER | IRQF_NOBALANCING, .handler = sirfsoc_timer_interrupt, }; static struct irqaction sirfsoc_timer1_irq = { .name = "sirfsoc_timer1", .flags = IRQF_TIMER | IRQF_NOBALANCING, .handler = sirfsoc_timer_interrupt, };
static int sirfsoc_local_timer_setup(struct clock_event_device *ce) { int cpu = smp_processor_id(); struct irqaction *action; if (cpu == 0) action = &sirfsoc_timer_irq; else action = &sirfsoc_timer1_irq; ce->irq = action->irq; ce->name = "local_timer"; ce->features = CLOCK_EVT_FEAT_ONESHOT; ce->rating = 200; ce->set_state_shutdown = sirfsoc_timer_shutdown; ce->set_state_oneshot = sirfsoc_timer_shutdown; ce->tick_resume = sirfsoc_timer_shutdown; ce->set_next_event = sirfsoc_timer_set_next_event; clockevents_calc_mult_shift(ce, atlas7_timer_rate, 60); ce->max_delta_ns = clockevent_delta2ns(-2, ce); ce->min_delta_ns = clockevent_delta2ns(2, ce); ce->cpumask = cpumask_of(cpu); action->dev_id = ce; BUG_ON(setup_irq(ce->irq, action)); irq_force_affinity(action->irq, cpumask_of(cpu)); clockevents_register_device(ce); return 0; }

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static void sirfsoc_local_timer_stop(struct clock_event_device *ce) { int cpu = smp_processor_id(); sirfsoc_timer_count_disable(1); if (cpu == 0) remove_irq(sirfsoc_timer_irq.irq, &sirfsoc_timer_irq); else remove_irq(sirfsoc_timer1_irq.irq, &sirfsoc_timer1_irq); }

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static int sirfsoc_cpu_notify(struct notifier_block *self, unsigned long action, void *hcpu) { /* * Grab cpu pointer in each case to avoid spurious * preemptible warnings */ switch (action & ~CPU_TASKS_FROZEN) { case CPU_STARTING: sirfsoc_local_timer_setup(this_cpu_ptr(sirfsoc_clockevent)); break; case CPU_DYING: sirfsoc_local_timer_stop(this_cpu_ptr(sirfsoc_clockevent)); break; } return NOTIFY_OK; }

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static struct notifier_block sirfsoc_cpu_nb = { .notifier_call = sirfsoc_cpu_notify, };
static void __init sirfsoc_clockevent_init(void) { sirfsoc_clockevent = alloc_percpu(struct clock_event_device); BUG_ON(!sirfsoc_clockevent); BUG_ON(register_cpu_notifier(&sirfsoc_cpu_nb)); /* Immediately configure the timer on the boot CPU */ sirfsoc_local_timer_setup(this_cpu_ptr(sirfsoc_clockevent)); }

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/* initialize the kernel jiffy timer source */
static void __init sirfsoc_atlas7_timer_init(struct device_node *np) { struct clk *clk; clk = of_clk_get(np, 0); BUG_ON(IS_ERR(clk)); BUG_ON(clk_prepare_enable(clk)); atlas7_timer_rate = clk_get_rate(clk); /* timer dividers: 0, not divided */ writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_CTRL); writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_32COUNTER_0_CTRL); writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_32COUNTER_1_CTRL); /* Initialize timer counters to 0 */ writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_LOAD_LO); writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_LOAD_HI); writel_relaxed(readl_relaxed(sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_CTRL) | BIT(1) | BIT(0), sirfsoc_timer_base + SIRFSOC_TIMER_64COUNTER_CTRL); writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_0); writel_relaxed(0, sirfsoc_timer_base + SIRFSOC_TIMER_COUNTER_1); /* Clear all interrupts */ writel_relaxed(0xFFFF, sirfsoc_timer_base + SIRFSOC_TIMER_INTR_STATUS); BUG_ON(clocksource_register_hz(&sirfsoc_clocksource, atlas7_timer_rate)); sirfsoc_clockevent_init(); }

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static void __init sirfsoc_of_timer_init(struct device_node *np) { sirfsoc_timer_base = of_iomap(np, 0); if (!sirfsoc_timer_base) panic("unable to map timer cpu registers\n"); sirfsoc_timer_irq.irq = irq_of_parse_and_map(np, 0); if (!sirfsoc_timer_irq.irq) panic("No irq passed for timer0 via DT\n"); sirfsoc_timer1_irq.irq = irq_of_parse_and_map(np, 1); if (!sirfsoc_timer1_irq.irq) panic("No irq passed for timer1 via DT\n"); sirfsoc_atlas7_timer_init(np); }

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CLOCKSOURCE_OF_DECLARE(sirfsoc_atlas7_timer, "sirf,atlas7-tick", sirfsoc_of_timer_init);

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