[linux-2.6-block.git] / drivers / clocksource / bcm_kona_timer.c

// SPDX-License-Identifier: GPL-2.0
// Copyright (C) 2012 Broadcom Corporation

#include <linux/init.h>
#include <linux/irq.h>
#include <linux/interrupt.h>
#include <linux/jiffies.h>
#include <linux/clockchips.h>
#include <linux/types.h>
#include <linux/clk.h>

#include <linux/io.h>

#include <linux/of.h>
#include <linux/of_address.h>
#include <linux/of_irq.h>


#define KONA_GPTIMER_STCS_OFFSET			0x00000000
#define KONA_GPTIMER_STCLO_OFFSET			0x00000004
#define KONA_GPTIMER_STCHI_OFFSET			0x00000008
#define KONA_GPTIMER_STCM0_OFFSET			0x0000000C

#define KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT		0
#define KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT		4

struct kona_bcm_timers {
	int tmr_irq;
	void __iomem *tmr_regs;
};

static struct kona_bcm_timers timers;

static u32 arch_timer_rate;

/*
 * We use the peripheral timers for system tick, the cpu global timer for
 * profile tick
 */
static void kona_timer_disable_and_clear(void __iomem *base)
{
	uint32_t reg;

	/*
	 * clear and disable interrupts
	 * We are using compare/match register 0 for our system interrupts
	 */
	reg = readl(base + KONA_GPTIMER_STCS_OFFSET);

	/* Clear compare (0) interrupt */
	reg |= 1 << KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT;
	/* disable compare */
	reg &= ~(1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);

	writel(reg, base + KONA_GPTIMER_STCS_OFFSET);

}

static int
kona_timer_get_counter(void __iomem *timer_base, uint32_t *msw, uint32_t *lsw)
{
	int loop_limit = 3;

	/*
	 * Read 64-bit free running counter
	 * 1. Read hi-word
	 * 2. Read low-word
	 * 3. Read hi-word again
	 * 4.1
	 *      if new hi-word is not equal to previously read hi-word, then
	 *      start from #1
	 * 4.2
	 *      if new hi-word is equal to previously read hi-word then stop.
	 */

	do {
		*msw = readl(timer_base + KONA_GPTIMER_STCHI_OFFSET);
		*lsw = readl(timer_base + KONA_GPTIMER_STCLO_OFFSET);
		if (*msw == readl(timer_base + KONA_GPTIMER_STCHI_OFFSET))
			break;
	} while (--loop_limit);
	if (!loop_limit) {
		pr_err("bcm_kona_timer: getting counter failed.\n");
		pr_err(" Timer will be impacted\n");
		return -ETIMEDOUT;
	}

	return 0;
}

static int kona_timer_set_next_event(unsigned long clc,
				  struct clock_event_device *unused)
{
	/*
	 * timer (0) is disabled by the timer interrupt already
	 * so, here we reload the next event value and re-enable
	 * the timer.
	 *
	 * This way, we are potentially losing the time between
	 * timer-interrupt->set_next_event. CPU local timers, when
	 * they come in should get rid of skew.
	 */

	uint32_t lsw, msw;
	uint32_t reg;
	int ret;

	ret = kona_timer_get_counter(timers.tmr_regs, &msw, &lsw);
	if (ret)
		return ret;

	/* Load the "next" event tick value */
	writel(lsw + clc, timers.tmr_regs + KONA_GPTIMER_STCM0_OFFSET);

	/* Enable compare */
	reg = readl(timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
	reg |= (1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
	writel(reg, timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);

	return 0;
}

static int kona_timer_shutdown(struct clock_event_device *evt)
{
	kona_timer_disable_and_clear(timers.tmr_regs);
	return 0;
}

static struct clock_event_device kona_clockevent_timer = {
	.name = "timer 1",
	.features = CLOCK_EVT_FEAT_ONESHOT,
	.set_next_event = kona_timer_set_next_event,
	.set_state_shutdown = kona_timer_shutdown,
	.tick_resume = kona_timer_shutdown,
};

static void __init kona_timer_clockevents_init(void)
{
	kona_clockevent_timer.cpumask = cpumask_of(0);
	clockevents_config_and_register(&kona_clockevent_timer,
		arch_timer_rate, 6, 0xffffffff);
}

static irqreturn_t kona_timer_interrupt(int irq, void *dev_id)
{
	struct clock_event_device *evt = &kona_clockevent_timer;

	kona_timer_disable_and_clear(timers.tmr_regs);
	evt->event_handler(evt);
	return IRQ_HANDLED;
}

static int __init kona_timer_init(struct device_node *node)
{
	u32 freq;
	struct clk *external_clk;

	external_clk = of_clk_get_by_name(node, NULL);

	if (!IS_ERR(external_clk)) {
		arch_timer_rate = clk_get_rate(external_clk);
		clk_prepare_enable(external_clk);
	} else if (!of_property_read_u32(node, "clock-frequency", &freq)) {
		arch_timer_rate = freq;
	} else {
		pr_err("Kona Timer v1 unable to determine clock-frequency\n");
		return -EINVAL;
	}

	/* Setup IRQ numbers */
	timers.tmr_irq = irq_of_parse_and_map(node, 0);

	/* Setup IO addresses */
	timers.tmr_regs = of_iomap(node, 0);

	kona_timer_disable_and_clear(timers.tmr_regs);

	kona_timer_clockevents_init();
	if (request_irq(timers.tmr_irq, kona_timer_interrupt, IRQF_TIMER,
			"Kona Timer Tick", NULL))
		pr_err("%s: request_irq() failed\n", "Kona Timer Tick");
	kona_timer_set_next_event((arch_timer_rate / HZ), NULL);

	return 0;
}

TIMER_OF_DECLARE(brcm_kona, "brcm,kona-timer", kona_timer_init);
/*
 * bcm,kona-timer is deprecated by brcm,kona-timer
 * being kept here for driver compatibility
 */
TIMER_OF_DECLARE(bcm_kona, "bcm,kona-timer", kona_timer_init);
Commit	Line	Data
	1	// SPDX-License-Identifier: GPL-2.0
	2	// Copyright (C) 2012 Broadcom Corporation
	3
	4	#include <linux/init.h>
	5	#include <linux/irq.h>
	6	#include <linux/interrupt.h>
	7	#include <linux/jiffies.h>
	8	#include <linux/clockchips.h>
	9	#include <linux/types.h>
	10	#include <linux/clk.h>
	11
	12	#include <linux/io.h>
	13
	14	#include <linux/of.h>
	15	#include <linux/of_address.h>
	16	#include <linux/of_irq.h>
	17
	18
	19	#define KONA_GPTIMER_STCS_OFFSET 0x00000000
	20	#define KONA_GPTIMER_STCLO_OFFSET 0x00000004
	21	#define KONA_GPTIMER_STCHI_OFFSET 0x00000008
	22	#define KONA_GPTIMER_STCM0_OFFSET 0x0000000C
	23
	24	#define KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT 0
	25	#define KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT 4
	26
	27	struct kona_bcm_timers {
	28	int tmr_irq;
	29	void __iomem *tmr_regs;
	30	};
	31
	32	static struct kona_bcm_timers timers;
	33
	34	static u32 arch_timer_rate;
	35
	36	/*
	37	* We use the peripheral timers for system tick, the cpu global timer for
	38	* profile tick
	39	*/
	40	static void kona_timer_disable_and_clear(void __iomem *base)
	41	{
	42	uint32_t reg;
	43
	44	/*
	45	* clear and disable interrupts
	46	* We are using compare/match register 0 for our system interrupts
	47	*/
	48	reg = readl(base + KONA_GPTIMER_STCS_OFFSET);
	49
	50	/* Clear compare (0) interrupt */
	51	reg \|= 1 << KONA_GPTIMER_STCS_TIMER_MATCH_SHIFT;
	52	/* disable compare */
	53	reg &= ~(1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
	54
	55	writel(reg, base + KONA_GPTIMER_STCS_OFFSET);
	56
	57	}
	58
	59	static int
	60	kona_timer_get_counter(void __iomem timer_base, uint32_t msw, uint32_t *lsw)
	61	{
	62	int loop_limit = 3;
	63
	64	/*
	65	* Read 64-bit free running counter
	66	* 1. Read hi-word
	67	* 2. Read low-word
	68	* 3. Read hi-word again
	69	* 4.1
	70	* if new hi-word is not equal to previously read hi-word, then
	71	* start from #1
	72	* 4.2
	73	* if new hi-word is equal to previously read hi-word then stop.
	74	*/
	75
	76	do {
	77	*msw = readl(timer_base + KONA_GPTIMER_STCHI_OFFSET);
	78	*lsw = readl(timer_base + KONA_GPTIMER_STCLO_OFFSET);
	79	if (*msw == readl(timer_base + KONA_GPTIMER_STCHI_OFFSET))
	80	break;
	81	} while (--loop_limit);
	82	if (!loop_limit) {
	83	pr_err("bcm_kona_timer: getting counter failed.\n");
	84	pr_err(" Timer will be impacted\n");
	85	return -ETIMEDOUT;
	86	}
	87
	88	return 0;
	89	}
	90
	91	static int kona_timer_set_next_event(unsigned long clc,
	92	struct clock_event_device *unused)
	93	{
	94	/*
	95	* timer (0) is disabled by the timer interrupt already
	96	* so, here we reload the next event value and re-enable
	97	* the timer.
	98	*
	99	* This way, we are potentially losing the time between
	100	* timer-interrupt->set_next_event. CPU local timers, when
	101	* they come in should get rid of skew.
	102	*/
	103
	104	uint32_t lsw, msw;
	105	uint32_t reg;
	106	int ret;
	107
	108	ret = kona_timer_get_counter(timers.tmr_regs, &msw, &lsw);
	109	if (ret)
	110	return ret;
	111
	112	/* Load the "next" event tick value */
	113	writel(lsw + clc, timers.tmr_regs + KONA_GPTIMER_STCM0_OFFSET);
	114
	115	/* Enable compare */
	116	reg = readl(timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
	117	reg \|= (1 << KONA_GPTIMER_STCS_COMPARE_ENABLE_SHIFT);
	118	writel(reg, timers.tmr_regs + KONA_GPTIMER_STCS_OFFSET);
	119
	120	return 0;
	121	}
	122
	123	static int kona_timer_shutdown(struct clock_event_device *evt)
	124	{
	125	kona_timer_disable_and_clear(timers.tmr_regs);
	126	return 0;
	127	}
	128
	129	static struct clock_event_device kona_clockevent_timer = {
	130	.name = "timer 1",
	131	.features = CLOCK_EVT_FEAT_ONESHOT,
	132	.set_next_event = kona_timer_set_next_event,
	133	.set_state_shutdown = kona_timer_shutdown,
	134	.tick_resume = kona_timer_shutdown,
	135	};
	136
	137	static void __init kona_timer_clockevents_init(void)
	138	{
	139	kona_clockevent_timer.cpumask = cpumask_of(0);
	140	clockevents_config_and_register(&kona_clockevent_timer,
	141	arch_timer_rate, 6, 0xffffffff);
	142	}
	143
	144	static irqreturn_t kona_timer_interrupt(int irq, void *dev_id)
	145	{
	146	struct clock_event_device *evt = &kona_clockevent_timer;
	147
	148	kona_timer_disable_and_clear(timers.tmr_regs);
	149	evt->event_handler(evt);
	150	return IRQ_HANDLED;
	151	}
	152
	153	static int __init kona_timer_init(struct device_node *node)
	154	{
	155	u32 freq;
	156	struct clk *external_clk;
	157
	158	external_clk = of_clk_get_by_name(node, NULL);
	159
	160	if (!IS_ERR(external_clk)) {
	161	arch_timer_rate = clk_get_rate(external_clk);
	162	clk_prepare_enable(external_clk);
	163	} else if (!of_property_read_u32(node, "clock-frequency", &freq)) {
	164	arch_timer_rate = freq;
	165	} else {
	166	pr_err("Kona Timer v1 unable to determine clock-frequency\n");
	167	return -EINVAL;
	168	}
	169
	170	/* Setup IRQ numbers */
	171	timers.tmr_irq = irq_of_parse_and_map(node, 0);
	172
	173	/* Setup IO addresses */
	174	timers.tmr_regs = of_iomap(node, 0);
	175
	176	kona_timer_disable_and_clear(timers.tmr_regs);
	177
	178	kona_timer_clockevents_init();
	179	if (request_irq(timers.tmr_irq, kona_timer_interrupt, IRQF_TIMER,
	180	"Kona Timer Tick", NULL))
	181	pr_err("%s: request_irq() failed\n", "Kona Timer Tick");
	182	kona_timer_set_next_event((arch_timer_rate / HZ), NULL);
	183
	184	return 0;
	185	}
	186
	187	TIMER_OF_DECLARE(brcm_kona, "brcm,kona-timer", kona_timer_init);
	188	/*
	189	* bcm,kona-timer is deprecated by brcm,kona-timer
	190	* being kept here for driver compatibility
	191	*/
	192	TIMER_OF_DECLARE(bcm_kona, "bcm,kona-timer", kona_timer_init);