clps711x-timer.c

  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *  Cirrus Logic CLPS711X clocksource driver
  4 *
  5 *  Copyright (C) 2014 Alexander Shiyan <shc_work@mail.ru>
  6 */
  7
  8#include <linux/clk.h>
  9#include <linux/clockchips.h>
 10#include <linux/clocksource.h>
 11#include <linux/interrupt.h>
 12#include <linux/io.h>
 13#include <linux/of_address.h>
 14#include <linux/of_irq.h>
 15#include <linux/sched_clock.h>
 16#include <linux/slab.h>
 17
 18enum {
 19	CLPS711X_CLKSRC_CLOCKSOURCE,
 20	CLPS711X_CLKSRC_CLOCKEVENT,
 21};
 22
 23static void __iomem *tcd;
 24
 25static u64 notrace clps711x_sched_clock_read(void)
 26{
 27	return ~readw(tcd);
 28}
 29
 30static void __init clps711x_clksrc_init(struct clk *clock, void __iomem *base)
 31{
 32	unsigned long rate = clk_get_rate(clock);
 33
 34	tcd = base;
 35
 36	clocksource_mmio_init(tcd, "clps711x-clocksource", rate, 300, 16,
 37			      clocksource_mmio_readw_down);
 38
 39	sched_clock_register(clps711x_sched_clock_read, 16, rate);
 40}
 41
 42static irqreturn_t clps711x_timer_interrupt(int irq, void *dev_id)
 43{
 44	struct clock_event_device *evt = dev_id;
 45
 46	evt->event_handler(evt);
 47
 48	return IRQ_HANDLED;
 49}
 50
 51static int __init _clps711x_clkevt_init(struct clk *clock, void __iomem *base,
 52					unsigned int irq)
 53{
 54	struct clock_event_device *clkevt;
 55	unsigned long rate;
 56
 57	clkevt = kzalloc(sizeof(*clkevt), GFP_KERNEL);
 58	if (!clkevt)
 59		return -ENOMEM;
 60
 61	rate = clk_get_rate(clock);
 62
 63	/* Set Timer prescaler */
 64	writew(DIV_ROUND_CLOSEST(rate, HZ), base);
 65
 66	clkevt->name = "clps711x-clockevent";
 67	clkevt->rating = 300;
 68	clkevt->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_C3STOP;
 69	clkevt->cpumask = cpumask_of(0);
 70	clockevents_config_and_register(clkevt, HZ, 0, 0);
 71
 72	return request_irq(irq, clps711x_timer_interrupt, IRQF_TIMER,
 73			   "clps711x-timer", clkevt);
 74}
 75
 76static int __init clps711x_timer_init(struct device_node *np)
 77{
 78	unsigned int irq = irq_of_parse_and_map(np, 0);
 79	struct clk *clock = of_clk_get(np, 0);
 80	void __iomem *base = of_iomap(np, 0);
 81	int ret = 0;
 82
 83	if (!base)
 84		return -ENOMEM;
 85	if (!irq) {
 86		ret = -EINVAL;
 87		goto unmap_io;
 88	}
 89	if (IS_ERR(clock)) {
 90		ret = PTR_ERR(clock);
 91		goto unmap_io;
 92	}
 93
 94	switch (of_alias_get_id(np, "timer")) {
 95	case CLPS711X_CLKSRC_CLOCKSOURCE:
 96		clps711x_clksrc_init(clock, base);
 97		break;
 98	case CLPS711X_CLKSRC_CLOCKEVENT:
 99		ret =  _clps711x_clkevt_init(clock, base, irq);
100		break;
101	default:
102		ret = -EINVAL;
103		break;
104	}
105
106unmap_io:
107	iounmap(base);
108	return ret;
109}
110TIMER_OF_DECLARE(clps711x, "cirrus,ep7209-timer", clps711x_timer_init);