![Marc Zyngier](/assets/img/avatar_default.png)
The sun4i timer can still be ticking when we enable the interrupt. If another timer is actually used (A7 architected timer, for example), odds are that the interrupt will eventually fire with the event_handler pointer being NULL. The obvious fix it to stop the timer before registering the interrupt. Observed and tested on sun7i (cubietruck). Cc: Daniel Lezcano <daniel.lezcano@linaro.org> Acked-by: Maxime Ripard <maxime.ripard@free-electrons.com> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
200 lines
5.2 KiB
C
200 lines
5.2 KiB
C
/*
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* Allwinner A1X SoCs timer handling.
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*
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* Copyright (C) 2012 Maxime Ripard
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*
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* Maxime Ripard <maxime.ripard@free-electrons.com>
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*
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* Based on code from
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* Allwinner Technology Co., Ltd. <www.allwinnertech.com>
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* Benn Huang <benn@allwinnertech.com>
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*
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* This file is licensed under the terms of the GNU General Public
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* License version 2. This program is licensed "as is" without any
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* warranty of any kind, whether express or implied.
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*/
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#include <linux/clk.h>
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#include <linux/clockchips.h>
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#include <linux/interrupt.h>
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#include <linux/irq.h>
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#include <linux/irqreturn.h>
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#include <linux/sched_clock.h>
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#include <linux/of.h>
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#include <linux/of_address.h>
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#include <linux/of_irq.h>
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#define TIMER_IRQ_EN_REG 0x00
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#define TIMER_IRQ_EN(val) BIT(val)
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#define TIMER_IRQ_ST_REG 0x04
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#define TIMER_CTL_REG(val) (0x10 * val + 0x10)
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#define TIMER_CTL_ENABLE BIT(0)
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#define TIMER_CTL_RELOAD BIT(1)
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#define TIMER_CTL_CLK_SRC(val) (((val) & 0x3) << 2)
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#define TIMER_CTL_CLK_SRC_OSC24M (1)
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#define TIMER_CTL_CLK_PRES(val) (((val) & 0x7) << 4)
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#define TIMER_CTL_ONESHOT BIT(7)
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#define TIMER_INTVAL_REG(val) (0x10 * (val) + 0x14)
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#define TIMER_CNTVAL_REG(val) (0x10 * (val) + 0x18)
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#define TIMER_SYNC_TICKS 3
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static void __iomem *timer_base;
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static u32 ticks_per_jiffy;
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/*
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* When we disable a timer, we need to wait at least for 2 cycles of
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* the timer source clock. We will use for that the clocksource timer
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* that is already setup and runs at the same frequency than the other
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* timers, and we never will be disabled.
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*/
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static void sun4i_clkevt_sync(void)
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{
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u32 old = readl(timer_base + TIMER_CNTVAL_REG(1));
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while ((old - readl(timer_base + TIMER_CNTVAL_REG(1))) < TIMER_SYNC_TICKS)
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cpu_relax();
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}
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static void sun4i_clkevt_time_stop(u8 timer)
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{
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u32 val = readl(timer_base + TIMER_CTL_REG(timer));
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writel(val & ~TIMER_CTL_ENABLE, timer_base + TIMER_CTL_REG(timer));
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sun4i_clkevt_sync();
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}
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static void sun4i_clkevt_time_setup(u8 timer, unsigned long delay)
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{
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writel(delay, timer_base + TIMER_INTVAL_REG(timer));
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}
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static void sun4i_clkevt_time_start(u8 timer, bool periodic)
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{
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u32 val = readl(timer_base + TIMER_CTL_REG(timer));
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if (periodic)
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val &= ~TIMER_CTL_ONESHOT;
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else
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val |= TIMER_CTL_ONESHOT;
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writel(val | TIMER_CTL_ENABLE | TIMER_CTL_RELOAD,
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timer_base + TIMER_CTL_REG(timer));
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}
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static void sun4i_clkevt_mode(enum clock_event_mode mode,
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struct clock_event_device *clk)
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{
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switch (mode) {
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case CLOCK_EVT_MODE_PERIODIC:
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sun4i_clkevt_time_stop(0);
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sun4i_clkevt_time_setup(0, ticks_per_jiffy);
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sun4i_clkevt_time_start(0, true);
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break;
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case CLOCK_EVT_MODE_ONESHOT:
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sun4i_clkevt_time_stop(0);
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sun4i_clkevt_time_start(0, false);
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break;
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case CLOCK_EVT_MODE_UNUSED:
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case CLOCK_EVT_MODE_SHUTDOWN:
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default:
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sun4i_clkevt_time_stop(0);
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break;
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}
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}
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static int sun4i_clkevt_next_event(unsigned long evt,
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struct clock_event_device *unused)
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{
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sun4i_clkevt_time_stop(0);
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sun4i_clkevt_time_setup(0, evt - TIMER_SYNC_TICKS);
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sun4i_clkevt_time_start(0, false);
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return 0;
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}
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static struct clock_event_device sun4i_clockevent = {
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.name = "sun4i_tick",
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.rating = 300,
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.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT,
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.set_mode = sun4i_clkevt_mode,
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.set_next_event = sun4i_clkevt_next_event,
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};
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static irqreturn_t sun4i_timer_interrupt(int irq, void *dev_id)
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{
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struct clock_event_device *evt = (struct clock_event_device *)dev_id;
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writel(0x1, timer_base + TIMER_IRQ_ST_REG);
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evt->event_handler(evt);
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return IRQ_HANDLED;
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}
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static struct irqaction sun4i_timer_irq = {
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.name = "sun4i_timer0",
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.flags = IRQF_TIMER | IRQF_IRQPOLL,
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.handler = sun4i_timer_interrupt,
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.dev_id = &sun4i_clockevent,
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};
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static u32 sun4i_timer_sched_read(void)
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{
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return ~readl(timer_base + TIMER_CNTVAL_REG(1));
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}
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static void __init sun4i_timer_init(struct device_node *node)
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{
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unsigned long rate = 0;
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struct clk *clk;
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int ret, irq;
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u32 val;
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timer_base = of_iomap(node, 0);
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if (!timer_base)
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panic("Can't map registers");
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irq = irq_of_parse_and_map(node, 0);
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if (irq <= 0)
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panic("Can't parse IRQ");
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clk = of_clk_get(node, 0);
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if (IS_ERR(clk))
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panic("Can't get timer clock");
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clk_prepare_enable(clk);
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rate = clk_get_rate(clk);
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writel(~0, timer_base + TIMER_INTVAL_REG(1));
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writel(TIMER_CTL_ENABLE | TIMER_CTL_RELOAD |
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TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
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timer_base + TIMER_CTL_REG(1));
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setup_sched_clock(sun4i_timer_sched_read, 32, rate);
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clocksource_mmio_init(timer_base + TIMER_CNTVAL_REG(1), node->name,
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rate, 300, 32, clocksource_mmio_readl_down);
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ticks_per_jiffy = DIV_ROUND_UP(rate, HZ);
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writel(TIMER_CTL_CLK_SRC(TIMER_CTL_CLK_SRC_OSC24M),
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timer_base + TIMER_CTL_REG(0));
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/* Make sure timer is stopped before playing with interrupts */
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sun4i_clkevt_time_stop(0);
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ret = setup_irq(irq, &sun4i_timer_irq);
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if (ret)
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pr_warn("failed to setup irq %d\n", irq);
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/* Enable timer0 interrupt */
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val = readl(timer_base + TIMER_IRQ_EN_REG);
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writel(val | TIMER_IRQ_EN(0), timer_base + TIMER_IRQ_EN_REG);
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sun4i_clockevent.cpumask = cpumask_of(0);
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clockevents_config_and_register(&sun4i_clockevent, rate,
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TIMER_SYNC_TICKS, 0xffffffff);
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}
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CLOCKSOURCE_OF_DECLARE(sun4i, "allwinner,sun4i-timer",
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sun4i_timer_init);
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