[linux.git] / drivers / clocksource / arm_global_timer.c

/*
 * drivers/clocksource/arm_global_timer.c
 *
 * Copyright (C) 2013 STMicroelectronics (R&D) Limited.
 * Author: Stuart Menefy <[email protected]>
 * Author: Srinivas Kandagatla <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/clocksource.h>
#include <linux/clockchips.h>
#include <linux/cpu.h>
#include <linux/clk.h>
#include <linux/err.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_irq.h>
#include <linux/of_address.h>
#include <linux/sched_clock.h>

#include <asm/cputype.h>

#define GT_COUNTER0	0x00
#define GT_COUNTER1	0x04

#define GT_CONTROL	0x08
#define GT_CONTROL_TIMER_ENABLE		BIT(0)  /* this bit is NOT banked */
#define GT_CONTROL_COMP_ENABLE		BIT(1)	/* banked */
#define GT_CONTROL_IRQ_ENABLE		BIT(2)	/* banked */
#define GT_CONTROL_AUTO_INC		BIT(3)	/* banked */

#define GT_INT_STATUS	0x0c
#define GT_INT_STATUS_EVENT_FLAG	BIT(0)

#define GT_COMP0	0x10
#define GT_COMP1	0x14
#define GT_AUTO_INC	0x18

/*
 * We are expecting to be clocked by the ARM peripheral clock.
 *
 * Note: it is assumed we are using a prescaler value of zero, so this is
 * the units for all operations.
 */
static void __iomem *gt_base;
static unsigned long gt_clk_rate;
static int gt_ppi;
static struct clock_event_device __percpu *gt_evt;

/*
 * To get the value from the Global Timer Counter register proceed as follows:
 * 1. Read the upper 32-bit timer counter register
 * 2. Read the lower 32-bit timer counter register
 * 3. Read the upper 32-bit timer counter register again. If the value is
 *  different to the 32-bit upper value read previously, go back to step 2.
 *  Otherwise the 64-bit timer counter value is correct.
 */
static u64 gt_counter_read(void)
{
	u64 counter;
	u32 lower;
	u32 upper, old_upper;

	upper = readl_relaxed(gt_base + GT_COUNTER1);
	do {
		old_upper = upper;
		lower = readl_relaxed(gt_base + GT_COUNTER0);
		upper = readl_relaxed(gt_base + GT_COUNTER1);
	} while (upper != old_upper);

	counter = upper;
	counter <<= 32;
	counter |= lower;
	return counter;
}

/**
 * To ensure that updates to comparator value register do not set the
 * Interrupt Status Register proceed as follows:
 * 1. Clear the Comp Enable bit in the Timer Control Register.
 * 2. Write the lower 32-bit Comparator Value Register.
 * 3. Write the upper 32-bit Comparator Value Register.
 * 4. Set the Comp Enable bit and, if necessary, the IRQ enable bit.
 */
static void gt_compare_set(unsigned long delta, int periodic)
{
	u64 counter = gt_counter_read();
	unsigned long ctrl;

	counter += delta;
	ctrl = GT_CONTROL_TIMER_ENABLE;
	writel(ctrl, gt_base + GT_CONTROL);
	writel(lower_32_bits(counter), gt_base + GT_COMP0);
	writel(upper_32_bits(counter), gt_base + GT_COMP1);

	if (periodic) {
		writel(delta, gt_base + GT_AUTO_INC);
		ctrl |= GT_CONTROL_AUTO_INC;
	}

	ctrl |= GT_CONTROL_COMP_ENABLE | GT_CONTROL_IRQ_ENABLE;
	writel(ctrl, gt_base + GT_CONTROL);
}

static void gt_clockevent_set_mode(enum clock_event_mode mode,
				   struct clock_event_device *clk)
{
	unsigned long ctrl;

	switch (mode) {
	case CLOCK_EVT_MODE_PERIODIC:
		gt_compare_set(DIV_ROUND_CLOSEST(gt_clk_rate, HZ), 1);
		break;
	case CLOCK_EVT_MODE_ONESHOT:
	case CLOCK_EVT_MODE_UNUSED:
	case CLOCK_EVT_MODE_SHUTDOWN:
		ctrl = readl(gt_base + GT_CONTROL);
		ctrl &= ~(GT_CONTROL_COMP_ENABLE |
				GT_CONTROL_IRQ_ENABLE | GT_CONTROL_AUTO_INC);
		writel(ctrl, gt_base + GT_CONTROL);
		break;
	default:
		break;
	}
}

static int gt_clockevent_set_next_event(unsigned long evt,
					struct clock_event_device *unused)
{
	gt_compare_set(evt, 0);
	return 0;
}

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

	if (!(readl_relaxed(gt_base + GT_INT_STATUS) &
				GT_INT_STATUS_EVENT_FLAG))
		return IRQ_NONE;

	/**
	 * ERRATA 740657( Global Timer can send 2 interrupts for
	 * the same event in single-shot mode)
	 * Workaround:
	 *	Either disable single-shot mode.
	 *	Or
	 *	Modify the Interrupt Handler to avoid the
	 *	offending sequence. This is achieved by clearing
	 *	the Global Timer flag _after_ having incremented
	 *	the Comparator register	value to a higher value.
	 */
	if (evt->mode == CLOCK_EVT_MODE_ONESHOT)
		gt_compare_set(ULONG_MAX, 0);

	writel_relaxed(GT_INT_STATUS_EVENT_FLAG, gt_base + GT_INT_STATUS);
	evt->event_handler(evt);

	return IRQ_HANDLED;
}

static int gt_clockevents_init(struct clock_event_device *clk)
{
	int cpu = smp_processor_id();

	clk->name = "arm_global_timer";
	clk->features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
	clk->set_mode = gt_clockevent_set_mode;
	clk->set_next_event = gt_clockevent_set_next_event;
	clk->cpumask = cpumask_of(cpu);
	clk->rating = 300;
	clk->irq = gt_ppi;
	clockevents_config_and_register(clk, gt_clk_rate,
					1, 0xffffffff);
	enable_percpu_irq(clk->irq, IRQ_TYPE_NONE);
	return 0;
}

static void gt_clockevents_stop(struct clock_event_device *clk)
{
	gt_clockevent_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
	disable_percpu_irq(clk->irq);
}

static cycle_t gt_clocksource_read(struct clocksource *cs)
{
	return gt_counter_read();
}

static struct clocksource gt_clocksource = {
	.name	= "arm_global_timer",
	.rating	= 300,
	.read	= gt_clocksource_read,
	.mask	= CLOCKSOURCE_MASK(64),
	.flags	= CLOCK_SOURCE_IS_CONTINUOUS,
};

#ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
static u32 notrace gt_sched_clock_read(void)
{
	return gt_counter_read();
}
#endif

static void __init gt_clocksource_init(void)
{
	writel(0, gt_base + GT_CONTROL);
	writel(0, gt_base + GT_COUNTER0);
	writel(0, gt_base + GT_COUNTER1);
	/* enables timer on all the cores */
	writel(GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);

#ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
	setup_sched_clock(gt_sched_clock_read, 32, gt_clk_rate);
#endif
	clocksource_register_hz(&gt_clocksource, gt_clk_rate);
}

static int gt_cpu_notify(struct notifier_block *self, unsigned long action,
			 void *hcpu)
{
	switch (action & ~CPU_TASKS_FROZEN) {
	case CPU_STARTING:
		gt_clockevents_init(this_cpu_ptr(gt_evt));
		break;
	case CPU_DYING:
		gt_clockevents_stop(this_cpu_ptr(gt_evt));
		break;
	}

	return NOTIFY_OK;
}
static struct notifier_block gt_cpu_nb = {
	.notifier_call = gt_cpu_notify,
};

static void __init global_timer_of_register(struct device_node *np)
{
	struct clk *gt_clk;
	int err = 0;

	/*
	 * In r2p0 the comparators for each processor with the global timer
	 * fire when the timer value is greater than or equal to. In previous
	 * revisions the comparators fired when the timer value was equal to.
	 */
	if ((read_cpuid_id() & 0xf0000f) < 0x200000) {
		pr_warn("global-timer: non support for this cpu version.\n");
		return;
	}

	gt_ppi = irq_of_parse_and_map(np, 0);
	if (!gt_ppi) {
		pr_warn("global-timer: unable to parse irq\n");
		return;
	}

	gt_base = of_iomap(np, 0);
	if (!gt_base) {
		pr_warn("global-timer: invalid base address\n");
		return;
	}

	gt_clk = of_clk_get(np, 0);
	if (!IS_ERR(gt_clk)) {
		err = clk_prepare_enable(gt_clk);
		if (err)
			goto out_unmap;
	} else {
		pr_warn("global-timer: clk not found\n");
		err = -EINVAL;
		goto out_unmap;
	}

	gt_clk_rate = clk_get_rate(gt_clk);
	gt_evt = alloc_percpu(struct clock_event_device);
	if (!gt_evt) {
		pr_warn("global-timer: can't allocate memory\n");
		err = -ENOMEM;
		goto out_clk;
	}

	err = request_percpu_irq(gt_ppi, gt_clockevent_interrupt,
				 "gt", gt_evt);
	if (err) {
		pr_warn("global-timer: can't register interrupt %d (%d)\n",
			gt_ppi, err);
		goto out_free;
	}

	err = register_cpu_notifier(&gt_cpu_nb);
	if (err) {
		pr_warn("global-timer: unable to register cpu notifier.\n");
		goto out_irq;
	}

	/* Immediately configure the timer on the boot CPU */
	gt_clocksource_init();
	gt_clockevents_init(this_cpu_ptr(gt_evt));

	return;

out_irq:
	free_percpu_irq(gt_ppi, gt_evt);
out_free:
	free_percpu(gt_evt);
out_clk:
	clk_disable_unprepare(gt_clk);
out_unmap:
	iounmap(gt_base);
	WARN(err, "ARM Global timer register failed (%d)\n", err);
}

/* Only tested on r2p2 and r3p0  */
CLOCKSOURCE_OF_DECLARE(arm_gt, "arm,cortex-a9-global-timer",
			global_timer_of_register);
Commit	Line	Data
c1b40e44 SM	1	/*
	2	* drivers/clocksource/arm_global_timer.c
	3	*
	4	* Copyright (C) 2013 STMicroelectronics (R&D) Limited.
	5	* Author: Stuart Menefy <[email protected]>
	6	* Author: Srinivas Kandagatla <[email protected]>
	7	*
	8	* This program is free software; you can redistribute it and/or modify
	9	* it under the terms of the GNU General Public License version 2 as
	10	* published by the Free Software Foundation.
	11	*/
	12
	13	#include <linux/init.h>
	14	#include <linux/interrupt.h>
	15	#include <linux/clocksource.h>
	16	#include <linux/clockchips.h>
	17	#include <linux/cpu.h>
	18	#include <linux/clk.h>
	19	#include <linux/err.h>
	20	#include <linux/io.h>
	21	#include <linux/of.h>
	22	#include <linux/of_irq.h>
	23	#include <linux/of_address.h>
	24	#include <linux/sched_clock.h>
	25
	26	#include <asm/cputype.h>
	27
	28	#define GT_COUNTER0 0x00
	29	#define GT_COUNTER1 0x04
	30
	31	#define GT_CONTROL 0x08
	32	#define GT_CONTROL_TIMER_ENABLE BIT(0) /* this bit is NOT banked */
	33	#define GT_CONTROL_COMP_ENABLE BIT(1) /* banked */
	34	#define GT_CONTROL_IRQ_ENABLE BIT(2) /* banked */
	35	#define GT_CONTROL_AUTO_INC BIT(3) /* banked */
	36
	37	#define GT_INT_STATUS 0x0c
	38	#define GT_INT_STATUS_EVENT_FLAG BIT(0)
	39
	40	#define GT_COMP0 0x10
	41	#define GT_COMP1 0x14
	42	#define GT_AUTO_INC 0x18
	43
	44	/*
	45	* We are expecting to be clocked by the ARM peripheral clock.
	46	*
	47	* Note: it is assumed we are using a prescaler value of zero, so this is
	48	* the units for all operations.
	49	*/
	50	static void __iomem *gt_base;
	51	static unsigned long gt_clk_rate;
	52	static int gt_ppi;
	53	static struct clock_event_device __percpu *gt_evt;
	54
	55	/*
	56	* To get the value from the Global Timer Counter register proceed as follows:
	57	* 1. Read the upper 32-bit timer counter register
	58	* 2. Read the lower 32-bit timer counter register
	59	* 3. Read the upper 32-bit timer counter register again. If the value is
	60	* different to the 32-bit upper value read previously, go back to step 2.
	61	* Otherwise the 64-bit timer counter value is correct.
	62	*/
	63	static u64 gt_counter_read(void)
	64	{
65	u64 counter;
66	u32 lower;
67	u32 upper, old_upper;
68
69	upper = readl_relaxed(gt_base + GT_COUNTER1);
70	do {
71	old_upper = upper;
72	lower = readl_relaxed(gt_base + GT_COUNTER0);
73	upper = readl_relaxed(gt_base + GT_COUNTER1);
74	} while (upper != old_upper);
75
76	counter = upper;
77	counter <<= 32;
78	counter \|= lower;
79	return counter;
80	}
81
82	/**
83	* To ensure that updates to comparator value register do not set the
84	* Interrupt Status Register proceed as follows:
85	* 1. Clear the Comp Enable bit in the Timer Control Register.
86	* 2. Write the lower 32-bit Comparator Value Register.
87	* 3. Write the upper 32-bit Comparator Value Register.
88	* 4. Set the Comp Enable bit and, if necessary, the IRQ enable bit.
89	*/
90	static void gt_compare_set(unsigned long delta, int periodic)
91	{
92	u64 counter = gt_counter_read();
93	unsigned long ctrl;
94
95	counter += delta;
96	ctrl = GT_CONTROL_TIMER_ENABLE;
97	writel(ctrl, gt_base + GT_CONTROL);
98	writel(lower_32_bits(counter), gt_base + GT_COMP0);
99	writel(upper_32_bits(counter), gt_base + GT_COMP1);
100
101	if (periodic) {
102	writel(delta, gt_base + GT_AUTO_INC);
103	ctrl \|= GT_CONTROL_AUTO_INC;
104	}
105
106	ctrl \|= GT_CONTROL_COMP_ENABLE \| GT_CONTROL_IRQ_ENABLE;
107	writel(ctrl, gt_base + GT_CONTROL);
108	}
109
110	static void gt_clockevent_set_mode(enum clock_event_mode mode,
111	struct clock_event_device *clk)
112	{
113	unsigned long ctrl;
114
115	switch (mode) {
116	case CLOCK_EVT_MODE_PERIODIC:
117	gt_compare_set(DIV_ROUND_CLOSEST(gt_clk_rate, HZ), 1);
118	break;
119	case CLOCK_EVT_MODE_ONESHOT:
120	case CLOCK_EVT_MODE_UNUSED:
121	case CLOCK_EVT_MODE_SHUTDOWN:
122	ctrl = readl(gt_base + GT_CONTROL);
123	ctrl &= ~(GT_CONTROL_COMP_ENABLE \|
124	GT_CONTROL_IRQ_ENABLE \| GT_CONTROL_AUTO_INC);
125	writel(ctrl, gt_base + GT_CONTROL);
126	break;
127	default:
128	break;
129	}
130	}
131
132	static int gt_clockevent_set_next_event(unsigned long evt,
133	struct clock_event_device *unused)
134	{
135	gt_compare_set(evt, 0);
136	return 0;
137	}
138
139	static irqreturn_t gt_clockevent_interrupt(int irq, void *dev_id)
140	{
141	struct clock_event_device *evt = dev_id;
142
143	if (!(readl_relaxed(gt_base + GT_INT_STATUS) &
144	GT_INT_STATUS_EVENT_FLAG))
145	return IRQ_NONE;
146
147	/**
148	* ERRATA 740657( Global Timer can send 2 interrupts for
149	* the same event in single-shot mode)
150	* Workaround:
151	* Either disable single-shot mode.
152	* Or
153	* Modify the Interrupt Handler to avoid the
154	* offending sequence. This is achieved by clearing
155	* the Global Timer flag _after_ having incremented
156	* the Comparator register value to a higher value.
157	*/
158	if (evt->mode == CLOCK_EVT_MODE_ONESHOT)
159	gt_compare_set(ULONG_MAX, 0);
160
161	writel_relaxed(GT_INT_STATUS_EVENT_FLAG, gt_base + GT_INT_STATUS);
162	evt->event_handler(evt);
163
164	return IRQ_HANDLED;
165	}
166
8c37bb3a	167	static int gt_clockevents_init(struct clock_event_device *clk)
c1b40e44 SM	168	{
	169	int cpu = smp_processor_id();
	170
	171	clk->name = "arm_global_timer";
	172	clk->features = CLOCK_EVT_FEAT_PERIODIC \| CLOCK_EVT_FEAT_ONESHOT;
	173	clk->set_mode = gt_clockevent_set_mode;
	174	clk->set_next_event = gt_clockevent_set_next_event;
	175	clk->cpumask = cpumask_of(cpu);
	176	clk->rating = 300;
	177	clk->irq = gt_ppi;
	178	clockevents_config_and_register(clk, gt_clk_rate,
	179	1, 0xffffffff);
	180	enable_percpu_irq(clk->irq, IRQ_TYPE_NONE);
	181	return 0;
	182	}
	183
	184	static void gt_clockevents_stop(struct clock_event_device *clk)
	185	{
	186	gt_clockevent_set_mode(CLOCK_EVT_MODE_UNUSED, clk);
	187	disable_percpu_irq(clk->irq);
	188	}
	189
	190	static cycle_t gt_clocksource_read(struct clocksource *cs)
	191	{
	192	return gt_counter_read();
	193	}
	194
	195	static struct clocksource gt_clocksource = {
	196	.name = "arm_global_timer",
	197	.rating = 300,
	198	.read = gt_clocksource_read,
	199	.mask = CLOCKSOURCE_MASK(64),
	200	.flags = CLOCK_SOURCE_IS_CONTINUOUS,
	201	};
	202
	203	#ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
	204	static u32 notrace gt_sched_clock_read(void)
	205	{
	206	return gt_counter_read();
	207	}
	208	#endif
	209
	210	static void __init gt_clocksource_init(void)
	211	{
	212	writel(0, gt_base + GT_CONTROL);
	213	writel(0, gt_base + GT_COUNTER0);
	214	writel(0, gt_base + GT_COUNTER1);
	215	/* enables timer on all the cores */
	216	writel(GT_CONTROL_TIMER_ENABLE, gt_base + GT_CONTROL);
	217
	218	#ifdef CONFIG_CLKSRC_ARM_GLOBAL_TIMER_SCHED_CLOCK
	219	setup_sched_clock(gt_sched_clock_read, 32, gt_clk_rate);
	220	#endif
	221	clocksource_register_hz(&gt_clocksource, gt_clk_rate);
	222	}
	223
8c37bb3a PG	224	static int gt_cpu_notify(struct notifier_block *self, unsigned long action,
8c37bb3a PG	225	void *hcpu)
c1b40e44 SM	226	{
	227	switch (action & ~CPU_TASKS_FROZEN) {
	228	case CPU_STARTING:
	229	gt_clockevents_init(this_cpu_ptr(gt_evt));
	230	break;
	231	case CPU_DYING:
	232	gt_clockevents_stop(this_cpu_ptr(gt_evt));
	233	break;
	234	}
	235
	236	return NOTIFY_OK;
	237	}
8c37bb3a	238	static struct notifier_block gt_cpu_nb = {
c1b40e44 SM	239	.notifier_call = gt_cpu_notify,
	240	};
	241
	242	static void __init global_timer_of_register(struct device_node *np)
	243	{
	244	struct clk *gt_clk;
	245	int err = 0;
	246
	247	/*
	248	* In r2p0 the comparators for each processor with the global timer
	249	* fire when the timer value is greater than or equal to. In previous
	250	* revisions the comparators fired when the timer value was equal to.
	251	*/
	252	if ((read_cpuid_id() & 0xf0000f) < 0x200000) {
	253	pr_warn("global-timer: non support for this cpu version.\n");
	254	return;
	255	}
	256
	257	gt_ppi = irq_of_parse_and_map(np, 0);
	258	if (!gt_ppi) {
	259	pr_warn("global-timer: unable to parse irq\n");
	260	return;
	261	}
	262
	263	gt_base = of_iomap(np, 0);
	264	if (!gt_base) {
	265	pr_warn("global-timer: invalid base address\n");
	266	return;
	267	}
	268
	269	gt_clk = of_clk_get(np, 0);
	270	if (!IS_ERR(gt_clk)) {
	271	err = clk_prepare_enable(gt_clk);
	272	if (err)
	273	goto out_unmap;
	274	} else {
	275	pr_warn("global-timer: clk not found\n");
	276	err = -EINVAL;
	277	goto out_unmap;
	278	}
	279
	280	gt_clk_rate = clk_get_rate(gt_clk);
	281	gt_evt = alloc_percpu(struct clock_event_device);
	282	if (!gt_evt) {
	283	pr_warn("global-timer: can't allocate memory\n");
	284	err = -ENOMEM;
	285	goto out_clk;
	286	}
	287
	288	err = request_percpu_irq(gt_ppi, gt_clockevent_interrupt,
	289	"gt", gt_evt);
	290	if (err) {
	291	pr_warn("global-timer: can't register interrupt %d (%d)\n",
	292	gt_ppi, err);
	293	goto out_free;
	294	}
	295
	296	err = register_cpu_notifier(&gt_cpu_nb);
	297	if (err) {
	298	pr_warn("global-timer: unable to register cpu notifier.\n");
	299	goto out_irq;
	300	}
	301
	302	/* Immediately configure the timer on the boot CPU */
303	gt_clocksource_init();
304	gt_clockevents_init(this_cpu_ptr(gt_evt));
305
306	return;
307
308	out_irq:
309	free_percpu_irq(gt_ppi, gt_evt);
310	out_free:
311	free_percpu(gt_evt);
312	out_clk:
313	clk_disable_unprepare(gt_clk);
314	out_unmap:
315	iounmap(gt_base);
316	WARN(err, "ARM Global timer register failed (%d)\n", err);
317	}
318
319	/* Only tested on r2p2 and r3p0 */
320	CLOCKSOURCE_OF_DECLARE(arm_gt, "arm,cortex-a9-global-timer",
321	global_timer_of_register);