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![Mark Rutland](/assets/img/avatar_default.png)
Please do not apply this to mainline directly, instead please re-run the coccinelle script shown below and apply its output. For several reasons, it is desirable to use {READ,WRITE}_ONCE() in preference to ACCESS_ONCE(), and new code is expected to use one of the former. So far, there's been no reason to change most existing uses of ACCESS_ONCE(), as these aren't harmful, and changing them results in churn. However, for some features, the read/write distinction is critical to correct operation. To distinguish these cases, separate read/write accessors must be used. This patch migrates (most) remaining ACCESS_ONCE() instances to {READ,WRITE}_ONCE(), using the following coccinelle script: ---- // Convert trivial ACCESS_ONCE() uses to equivalent READ_ONCE() and // WRITE_ONCE() // $ make coccicheck COCCI=/home/mark/once.cocci SPFLAGS="--include-headers" MODE=patch virtual patch @ depends on patch @ expression E1, E2; @@ - ACCESS_ONCE(E1) = E2 + WRITE_ONCE(E1, E2) @ depends on patch @ expression E; @@ - ACCESS_ONCE(E) + READ_ONCE(E) ---- Signed-off-by: Mark Rutland <mark.rutland@arm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: davem@davemloft.net Cc: linux-arch@vger.kernel.org Cc: mpe@ellerman.id.au Cc: shuah@kernel.org Cc: snitzer@redhat.com Cc: thor.thayer@linux.intel.com Cc: tj@kernel.org Cc: viro@zeniv.linux.org.uk Cc: will.deacon@arm.com Link: http://lkml.kernel.org/r/1508792849-3115-19-git-send-email-paulmck@linux.vnet.ibm.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
151 lines
3.9 KiB
C
151 lines
3.9 KiB
C
/*
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* Copyright 2012 Simon Arlott
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include <linux/bitops.h>
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#include <linux/clockchips.h>
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#include <linux/clocksource.h>
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#include <linux/interrupt.h>
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#include <linux/irqreturn.h>
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/of_address.h>
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#include <linux/of_irq.h>
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#include <linux/of_platform.h>
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#include <linux/slab.h>
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#include <linux/string.h>
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#include <linux/sched_clock.h>
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#include <asm/irq.h>
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#define REG_CONTROL 0x00
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#define REG_COUNTER_LO 0x04
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#define REG_COUNTER_HI 0x08
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#define REG_COMPARE(n) (0x0c + (n) * 4)
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#define MAX_TIMER 3
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#define DEFAULT_TIMER 3
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struct bcm2835_timer {
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void __iomem *control;
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void __iomem *compare;
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int match_mask;
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struct clock_event_device evt;
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struct irqaction act;
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};
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static void __iomem *system_clock __read_mostly;
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static u64 notrace bcm2835_sched_read(void)
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{
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return readl_relaxed(system_clock);
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}
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static int bcm2835_time_set_next_event(unsigned long event,
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struct clock_event_device *evt_dev)
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{
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struct bcm2835_timer *timer = container_of(evt_dev,
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struct bcm2835_timer, evt);
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writel_relaxed(readl_relaxed(system_clock) + event,
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timer->compare);
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return 0;
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}
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static irqreturn_t bcm2835_time_interrupt(int irq, void *dev_id)
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{
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struct bcm2835_timer *timer = dev_id;
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void (*event_handler)(struct clock_event_device *);
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if (readl_relaxed(timer->control) & timer->match_mask) {
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writel_relaxed(timer->match_mask, timer->control);
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event_handler = READ_ONCE(timer->evt.event_handler);
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if (event_handler)
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event_handler(&timer->evt);
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return IRQ_HANDLED;
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} else {
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return IRQ_NONE;
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}
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}
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static int __init bcm2835_timer_init(struct device_node *node)
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{
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void __iomem *base;
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u32 freq;
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int irq, ret;
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struct bcm2835_timer *timer;
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base = of_iomap(node, 0);
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if (!base) {
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pr_err("Can't remap registers\n");
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return -ENXIO;
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}
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ret = of_property_read_u32(node, "clock-frequency", &freq);
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if (ret) {
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pr_err("Can't read clock-frequency\n");
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goto err_iounmap;
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}
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system_clock = base + REG_COUNTER_LO;
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sched_clock_register(bcm2835_sched_read, 32, freq);
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clocksource_mmio_init(base + REG_COUNTER_LO, node->name,
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freq, 300, 32, clocksource_mmio_readl_up);
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irq = irq_of_parse_and_map(node, DEFAULT_TIMER);
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if (irq <= 0) {
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pr_err("Can't parse IRQ\n");
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ret = -EINVAL;
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goto err_iounmap;
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}
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timer = kzalloc(sizeof(*timer), GFP_KERNEL);
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if (!timer) {
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ret = -ENOMEM;
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goto err_iounmap;
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}
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timer->control = base + REG_CONTROL;
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timer->compare = base + REG_COMPARE(DEFAULT_TIMER);
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timer->match_mask = BIT(DEFAULT_TIMER);
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timer->evt.name = node->name;
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timer->evt.rating = 300;
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timer->evt.features = CLOCK_EVT_FEAT_ONESHOT;
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timer->evt.set_next_event = bcm2835_time_set_next_event;
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timer->evt.cpumask = cpumask_of(0);
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timer->act.name = node->name;
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timer->act.flags = IRQF_TIMER | IRQF_SHARED;
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timer->act.dev_id = timer;
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timer->act.handler = bcm2835_time_interrupt;
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ret = setup_irq(irq, &timer->act);
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if (ret) {
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pr_err("Can't set up timer IRQ\n");
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goto err_iounmap;
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}
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clockevents_config_and_register(&timer->evt, freq, 0xf, 0xffffffff);
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pr_info("bcm2835: system timer (irq = %d)\n", irq);
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return 0;
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err_iounmap:
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iounmap(base);
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return ret;
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}
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TIMER_OF_DECLARE(bcm2835, "brcm,bcm2835-system-timer",
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bcm2835_timer_init);
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