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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * arch/arm/mach-vt8500/timer.c4 *5 * Copyright (C) 2012 Tony Prisk <linux@prisktech.co.nz>6 * Copyright (C) 2010 Alexey Charkov <alchark@gmail.com>7 */8 9/*10 * This file is copied and modified from the original timer.c provided by11 * Alexey Charkov. Minor changes have been made for Device Tree Support.12 */13 14#include <linux/io.h>15#include <linux/irq.h>16#include <linux/interrupt.h>17#include <linux/clocksource.h>18#include <linux/clockchips.h>19#include <linux/delay.h>20 21#include <linux/of.h>22#include <linux/of_address.h>23#include <linux/of_irq.h>24 25#define VT8500_TIMER_OFFSET 0x010026#define VT8500_TIMER_HZ 300000027#define TIMER_MATCH_VAL 0x000028#define TIMER_COUNT_VAL 0x001029#define TIMER_STATUS_VAL 0x001430#define TIMER_IER_VAL 0x001c /* interrupt enable */31#define TIMER_CTRL_VAL 0x002032#define TIMER_AS_VAL 0x0024 /* access status */33#define TIMER_COUNT_R_ACTIVE (1 << 5) /* not ready for read */34#define TIMER_COUNT_W_ACTIVE (1 << 4) /* not ready for write */35#define TIMER_MATCH_W_ACTIVE (1 << 0) /* not ready for write */36 37#define msecs_to_loops(t) (loops_per_jiffy / 1000 * HZ * t)38 39#define MIN_OSCR_DELTA 1640 41static void __iomem *regbase;42 43static u64 vt8500_timer_read(struct clocksource *cs)44{45 int loops = msecs_to_loops(10);46 writel(3, regbase + TIMER_CTRL_VAL);47 while ((readl((regbase + TIMER_AS_VAL)) & TIMER_COUNT_R_ACTIVE)48 && --loops)49 cpu_relax();50 return readl(regbase + TIMER_COUNT_VAL);51}52 53static struct clocksource clocksource = {54 .name = "vt8500_timer",55 .rating = 200,56 .read = vt8500_timer_read,57 .mask = CLOCKSOURCE_MASK(32),58 .flags = CLOCK_SOURCE_IS_CONTINUOUS,59};60 61static int vt8500_timer_set_next_event(unsigned long cycles,62 struct clock_event_device *evt)63{64 int loops = msecs_to_loops(10);65 u64 alarm = clocksource.read(&clocksource) + cycles;66 while ((readl(regbase + TIMER_AS_VAL) & TIMER_MATCH_W_ACTIVE)67 && --loops)68 cpu_relax();69 writel((unsigned long)alarm, regbase + TIMER_MATCH_VAL);70 71 if ((signed)(alarm - clocksource.read(&clocksource)) <= MIN_OSCR_DELTA)72 return -ETIME;73 74 writel(1, regbase + TIMER_IER_VAL);75 76 return 0;77}78 79static int vt8500_shutdown(struct clock_event_device *evt)80{81 writel(readl(regbase + TIMER_CTRL_VAL) | 1, regbase + TIMER_CTRL_VAL);82 writel(0, regbase + TIMER_IER_VAL);83 return 0;84}85 86static struct clock_event_device clockevent = {87 .name = "vt8500_timer",88 .features = CLOCK_EVT_FEAT_ONESHOT,89 .rating = 200,90 .set_next_event = vt8500_timer_set_next_event,91 .set_state_shutdown = vt8500_shutdown,92 .set_state_oneshot = vt8500_shutdown,93};94 95static irqreturn_t vt8500_timer_interrupt(int irq, void *dev_id)96{97 struct clock_event_device *evt = dev_id;98 writel(0xf, regbase + TIMER_STATUS_VAL);99 evt->event_handler(evt);100 101 return IRQ_HANDLED;102}103 104static int __init vt8500_timer_init(struct device_node *np)105{106 int timer_irq, ret;107 108 regbase = of_iomap(np, 0);109 if (!regbase) {110 pr_err("%s: Missing iobase description in Device Tree\n",111 __func__);112 return -ENXIO;113 }114 115 timer_irq = irq_of_parse_and_map(np, 0);116 if (!timer_irq) {117 pr_err("%s: Missing irq description in Device Tree\n",118 __func__);119 return -EINVAL;120 }121 122 writel(1, regbase + TIMER_CTRL_VAL);123 writel(0xf, regbase + TIMER_STATUS_VAL);124 writel(~0, regbase + TIMER_MATCH_VAL);125 126 ret = clocksource_register_hz(&clocksource, VT8500_TIMER_HZ);127 if (ret) {128 pr_err("%s: clocksource_register failed for %s\n",129 __func__, clocksource.name);130 return ret;131 }132 133 clockevent.cpumask = cpumask_of(0);134 135 ret = request_irq(timer_irq, vt8500_timer_interrupt,136 IRQF_TIMER | IRQF_IRQPOLL, "vt8500_timer",137 &clockevent);138 if (ret) {139 pr_err("%s: setup_irq failed for %s\n", __func__,140 clockevent.name);141 return ret;142 }143 144 clockevents_config_and_register(&clockevent, VT8500_TIMER_HZ,145 MIN_OSCR_DELTA * 2, 0xf0000000);146 147 return 0;148}149 150TIMER_OF_DECLARE(vt8500, "via,vt8500-timer", vt8500_timer_init);151