dw_apb_timer_of.c 4.6 KB
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// SPDX-License-Identifier: GPL-2.0-only
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/*
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 * Copyright (C) 2012 Altera Corporation
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 * Copyright (c) 2011 Picochip Ltd., Jamie Iles
 *
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 * Modified from mach-picoxcell/time.c
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 */
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#include <linux/delay.h>
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#include <linux/dw_apb_timer.h>
#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>
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#include <linux/clk.h>
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#include <linux/reset.h>
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#include <linux/sched_clock.h>
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static int __init timer_get_base_and_rate(struct device_node *np,
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				    void __iomem **base, u32 *rate)
{
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	struct clk *timer_clk;
	struct clk *pclk;
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	struct reset_control *rstc;
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	int ret;
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	*base = of_iomap(np, 0);

	if (!*base)
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		panic("Unable to map regs for %pOFn", np);
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	/*
	 * Reset the timer if the reset control is available, wiping
	 * out the state the firmware may have left it
	 */
	rstc = of_reset_control_get(np, NULL);
	if (!IS_ERR(rstc)) {
		reset_control_assert(rstc);
		reset_control_deassert(rstc);
	}

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	/*
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	 * Not all implementations use a peripheral clock, so don't panic
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	 * if it's not present
	 */
	pclk = of_clk_get_by_name(np, "pclk");
	if (!IS_ERR(pclk))
		if (clk_prepare_enable(pclk))
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			pr_warn("pclk for %pOFn is present, but could not be activated\n",
				np);
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	if (!of_property_read_u32(np, "clock-freq", rate) ||
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	    !of_property_read_u32(np, "clock-frequency", rate))
		return 0;

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	timer_clk = of_clk_get_by_name(np, "timer");
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	if (IS_ERR(timer_clk)) {
		ret = PTR_ERR(timer_clk);
		goto out_pclk_disable;
	}
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	ret = clk_prepare_enable(timer_clk);
	if (ret)
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		goto out_timer_clk_put;
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	*rate = clk_get_rate(timer_clk);
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	if (!(*rate)) {
		ret = -EINVAL;
		goto out_timer_clk_disable;
	}
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	return 0;
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out_timer_clk_disable:
	clk_disable_unprepare(timer_clk);
out_timer_clk_put:
	clk_put(timer_clk);
out_pclk_disable:
	if (!IS_ERR(pclk)) {
		clk_disable_unprepare(pclk);
		clk_put(pclk);
	}
	iounmap(*base);
	return ret;
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}

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static int __init add_clockevent(struct device_node *event_timer)
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{
	void __iomem *iobase;
	struct dw_apb_clock_event_device *ced;
	u32 irq, rate;
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	int ret = 0;
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	irq = irq_of_parse_and_map(event_timer, 0);
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	if (irq == 0)
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		panic("No IRQ for clock event timer");

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	ret = timer_get_base_and_rate(event_timer, &iobase, &rate);
	if (ret)
		return ret;
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	ced = dw_apb_clockevent_init(-1, event_timer->name, 300, iobase, irq,
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				     rate);
	if (!ced)
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		return -EINVAL;
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	dw_apb_clockevent_register(ced);
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	return 0;
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}

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static void __iomem *sched_io_base;
static u32 sched_rate;

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static int __init add_clocksource(struct device_node *source_timer)
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{
	void __iomem *iobase;
	struct dw_apb_clocksource *cs;
	u32 rate;
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	int ret;
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	ret = timer_get_base_and_rate(source_timer, &iobase, &rate);
	if (ret)
		return ret;
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	cs = dw_apb_clocksource_init(300, source_timer->name, iobase, rate);
	if (!cs)
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		return -EINVAL;
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	dw_apb_clocksource_start(cs);
	dw_apb_clocksource_register(cs);

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	/*
	 * Fallback to use the clocksource as sched_clock if no separate
	 * timer is found. sched_io_base then points to the current_value
	 * register of the clocksource timer.
	 */
	sched_io_base = iobase + 0x04;
	sched_rate = rate;
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	return 0;
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}
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static u64 notrace read_sched_clock(void)
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{
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	return ~readl_relaxed(sched_io_base);
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}

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static const struct of_device_id sptimer_ids[] __initconst = {
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	{ .compatible = "picochip,pc3x2-rtc" },
	{ /* Sentinel */ },
};

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static void __init init_sched_clock(void)
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{
	struct device_node *sched_timer;

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	sched_timer = of_find_matching_node(NULL, sptimer_ids);
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	if (sched_timer) {
		timer_get_base_and_rate(sched_timer, &sched_io_base,
					&sched_rate);
		of_node_put(sched_timer);
	}
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	sched_clock_register(read_sched_clock, 32, sched_rate);
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}

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#ifdef CONFIG_ARM
static unsigned long dw_apb_delay_timer_read(void)
{
	return ~readl_relaxed(sched_io_base);
}

static struct delay_timer dw_apb_delay_timer = {
	.read_current_timer	= dw_apb_delay_timer_read,
};
#endif

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static int num_called;
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static int __init dw_apb_timer_init(struct device_node *timer)
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{
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	int ret = 0;

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	switch (num_called) {
	case 1:
		pr_debug("%s: found clocksource timer\n", __func__);
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		ret = add_clocksource(timer);
		if (ret)
			return ret;
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		init_sched_clock();
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#ifdef CONFIG_ARM
		dw_apb_delay_timer.freq = sched_rate;
		register_current_timer_delay(&dw_apb_delay_timer);
#endif
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		break;
	default:
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		pr_debug("%s: found clockevent timer\n", __func__);
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		ret = add_clockevent(timer);
		if (ret)
			return ret;
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		break;
	}
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	num_called++;
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	return 0;
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}
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TIMER_OF_DECLARE(pc3x2_timer, "picochip,pc3x2-timer", dw_apb_timer_init);
TIMER_OF_DECLARE(apb_timer_osc, "snps,dw-apb-timer-osc", dw_apb_timer_init);
TIMER_OF_DECLARE(apb_timer_sp, "snps,dw-apb-timer-sp", dw_apb_timer_init);
TIMER_OF_DECLARE(apb_timer, "snps,dw-apb-timer", dw_apb_timer_init);