cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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timer-vt8500.c (3988B)

      1// SPDX-License-Identifier: GPL-2.0-or-later
      2/*
      3 *  arch/arm/mach-vt8500/timer.c
      4 *
      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 by
     11 * 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	0x0100
     26#define VT8500_TIMER_HZ		3000000
     27#define TIMER_MATCH_VAL		0x0000
     28#define TIMER_COUNT_VAL		0x0010
     29#define TIMER_STATUS_VAL	0x0014
     30#define TIMER_IER_VAL		0x001c		/* interrupt enable */
     31#define TIMER_CTRL_VAL		0x0020
     32#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		16
     40
     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);