cregit-Linux how code gets into the kernel

Release 4.7 drivers/clocksource/timer-integrator-ap.c

/*
 * Integrator/AP timer driver
 * Copyright (C) 2000-2003 Deep Blue Solutions Ltd
 * Copyright (c) 2014, Linaro Limited
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include <linux/clk.h>
#include <linux/clocksource.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <linux/of_platform.h>
#include <linux/clockchips.h>
#include <linux/interrupt.h>
#include <linux/sched_clock.h>

#include "timer-sp.h"


static void __iomem * sched_clk_base;


static u64 notrace integrator_read_sched_clock(void) { return -readl(sched_clk_base + TIMER_VALUE); }

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static void integrator_clocksource_init(unsigned long inrate, void __iomem *base) { u32 ctrl = TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC; unsigned long rate = inrate; if (rate >= 1500000) { rate /= 16; ctrl |= TIMER_CTRL_DIV16; } writel(0xffff, base + TIMER_LOAD); writel(ctrl, base + TIMER_CTRL); clocksource_mmio_init(base + TIMER_VALUE, "timer2", rate, 200, 16, clocksource_mmio_readl_down); sched_clk_base = base; sched_clock_register(integrator_read_sched_clock, 16, rate); }

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static unsigned long timer_reload; static void __iomem * clkevt_base; /* * IRQ handler for the timer */
static irqreturn_t integrator_timer_interrupt(int irq, void *dev_id) { struct clock_event_device *evt = dev_id; /* clear the interrupt */ writel(1, clkevt_base + TIMER_INTCLR); evt->event_handler(evt); return IRQ_HANDLED; }

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static int clkevt_shutdown(struct clock_event_device *evt) { u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE; /* Disable timer */ writel(ctrl, clkevt_base + TIMER_CTRL); return 0; }

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static int clkevt_set_oneshot(struct clock_event_device *evt) { u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~(TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC); /* Leave the timer disabled, .set_next_event will enable it */ writel(ctrl, clkevt_base + TIMER_CTRL); return 0; }

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static int clkevt_set_periodic(struct clock_event_device *evt) { u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE; /* Disable timer */ writel(ctrl, clkevt_base + TIMER_CTRL); /* Enable the timer and start the periodic tick */ writel(timer_reload, clkevt_base + TIMER_LOAD); ctrl |= TIMER_CTRL_PERIODIC | TIMER_CTRL_ENABLE; writel(ctrl, clkevt_base + TIMER_CTRL); return 0; }

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static int clkevt_set_next_event(unsigned long next, struct clock_event_device *evt) { unsigned long ctrl = readl(clkevt_base + TIMER_CTRL); writel(ctrl & ~TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL); writel(next, clkevt_base + TIMER_LOAD); writel(ctrl | TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL); return 0; }

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static struct clock_event_device integrator_clockevent = { .name = "timer1", .features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT, .set_state_shutdown = clkevt_shutdown, .set_state_periodic = clkevt_set_periodic, .set_state_oneshot = clkevt_set_oneshot, .tick_resume = clkevt_shutdown, .set_next_event = clkevt_set_next_event, .rating = 300, }; static struct irqaction integrator_timer_irq = { .name = "timer", .flags = IRQF_TIMER | IRQF_IRQPOLL, .handler = integrator_timer_interrupt, .dev_id = &integrator_clockevent, };
static void integrator_clockevent_init(unsigned long inrate, void __iomem *base, int irq) { unsigned long rate = inrate; unsigned int ctrl = 0; clkevt_base = base; /* Calculate and program a divisor */ if (rate > 0x100000 * HZ) { rate /= 256; ctrl |= TIMER_CTRL_DIV256; } else if (rate > 0x10000 * HZ) { rate /= 16; ctrl |= TIMER_CTRL_DIV16; } timer_reload = rate / HZ; writel(ctrl, clkevt_base + TIMER_CTRL); setup_irq(irq, &integrator_timer_irq); clockevents_config_and_register(&integrator_clockevent, rate, 1, 0xffffU); }

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static void __init integrator_ap_timer_init_of(struct device_node *node) { const char *path; void __iomem *base; int err; int irq; struct clk *clk; unsigned long rate; struct device_node *pri_node; struct device_node *sec_node; base = of_io_request_and_map(node, 0, "integrator-timer"); if (IS_ERR(base)) return; clk = of_clk_get(node, 0); if (IS_ERR(clk)) { pr_err("No clock for %s\n", node->name); return; } clk_prepare_enable(clk); rate = clk_get_rate(clk); writel(0, base + TIMER_CTRL); err = of_property_read_string(of_aliases, "arm,timer-primary", &path); if (WARN_ON(err)) return; pri_node = of_find_node_by_path(path); err = of_property_read_string(of_aliases, "arm,timer-secondary", &path); if (WARN_ON(err)) return; sec_node = of_find_node_by_path(path); if (node == pri_node) { /* The primary timer lacks IRQ, use as clocksource */ integrator_clocksource_init(rate, base); return; } if (node == sec_node) { /* The secondary timer will drive the clock event */ irq = irq_of_parse_and_map(node, 0); integrator_clockevent_init(rate, base, irq); return; } pr_info("Timer @%p unused\n", base); clk_disable_unprepare(clk); }

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CLOCKSOURCE_OF_DECLARE(integrator_ap_timer, "arm,integrator-timer", integrator_ap_timer_init_of);

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