1/*
2 * arch/arm/mach-pxa/time.c
3 *
4 * PXA clocksource, clockevents, and OST interrupt handlers.
5 * Copyright (c) 2007 by Bill Gatliff <bgat@billgatliff.com>.
6 *
7 * Derived from Nicolas Pitre's PXA timer handler Copyright (c) 2001
8 * by MontaVista Software, Inc.  (Nico, your code rocks!)
9 *
10 * This program is free software; you can redistribute it and/or modify
11 * it under the terms of the GNU General Public License version 2 as
12 * published by the Free Software Foundation.
13 */
14
15#include <linux/kernel.h>
16#include <linux/init.h>
17#include <linux/interrupt.h>
18#include <linux/clk.h>
19#include <linux/clockchips.h>
20#include <linux/of_address.h>
21#include <linux/of_irq.h>
22#include <linux/sched_clock.h>
23
24#include <asm/div64.h>
25
26#define OSMR0		0x00	/* OS Timer 0 Match Register */
27#define OSMR1		0x04	/* OS Timer 1 Match Register */
28#define OSMR2		0x08	/* OS Timer 2 Match Register */
29#define OSMR3		0x0C	/* OS Timer 3 Match Register */
30
31#define OSCR		0x10	/* OS Timer Counter Register */
32#define OSSR		0x14	/* OS Timer Status Register */
33#define OWER		0x18	/* OS Timer Watchdog Enable Register */
34#define OIER		0x1C	/* OS Timer Interrupt Enable Register */
35
36#define OSSR_M3		(1 << 3)	/* Match status channel 3 */
37#define OSSR_M2		(1 << 2)	/* Match status channel 2 */
38#define OSSR_M1		(1 << 1)	/* Match status channel 1 */
39#define OSSR_M0		(1 << 0)	/* Match status channel 0 */
40
41#define OIER_E0		(1 << 0)	/* Interrupt enable channel 0 */
42
43/*
44 * This is PXA's sched_clock implementation. This has a resolution
45 * of at least 308 ns and a maximum value of 208 days.
46 *
47 * The return value is guaranteed to be monotonic in that range as
48 * long as there is always less than 582 seconds between successive
49 * calls to sched_clock() which should always be the case in practice.
50 */
51
52#define timer_readl(reg) readl_relaxed(timer_base + (reg))
53#define timer_writel(val, reg) writel_relaxed((val), timer_base + (reg))
54
55static void __iomem *timer_base;
56
57static u64 notrace pxa_read_sched_clock(void)
58{
59	return timer_readl(OSCR);
60}
61
62
63#define MIN_OSCR_DELTA 16
64
65static irqreturn_t
66pxa_ost0_interrupt(int irq, void *dev_id)
67{
68	struct clock_event_device *c = dev_id;
69
70	/* Disarm the compare/match, signal the event. */
71	timer_writel(timer_readl(OIER) & ~OIER_E0, OIER);
72	timer_writel(OSSR_M0, OSSR);
73	c->event_handler(c);
74
75	return IRQ_HANDLED;
76}
77
78static int
79pxa_osmr0_set_next_event(unsigned long delta, struct clock_event_device *dev)
80{
81	unsigned long next, oscr;
82
83	timer_writel(timer_readl(OIER) | OIER_E0, OIER);
84	next = timer_readl(OSCR) + delta;
85	timer_writel(next, OSMR0);
86	oscr = timer_readl(OSCR);
87
88	return (signed)(next - oscr) <= MIN_OSCR_DELTA ? -ETIME : 0;
89}
90
91static int pxa_osmr0_shutdown(struct clock_event_device *evt)
92{
93	/* initializing, released, or preparing for suspend */
94	timer_writel(timer_readl(OIER) & ~OIER_E0, OIER);
95	timer_writel(OSSR_M0, OSSR);
96	return 0;
97}
98
99#ifdef CONFIG_PM
100static unsigned long osmr[4], oier, oscr;
101
102static void pxa_timer_suspend(struct clock_event_device *cedev)
103{
104	osmr[0] = timer_readl(OSMR0);
105	osmr[1] = timer_readl(OSMR1);
106	osmr[2] = timer_readl(OSMR2);
107	osmr[3] = timer_readl(OSMR3);
108	oier = timer_readl(OIER);
109	oscr = timer_readl(OSCR);
110}
111
112static void pxa_timer_resume(struct clock_event_device *cedev)
113{
114	/*
115	 * Ensure that we have at least MIN_OSCR_DELTA between match
116	 * register 0 and the OSCR, to guarantee that we will receive
117	 * the one-shot timer interrupt.  We adjust OSMR0 in preference
118	 * to OSCR to guarantee that OSCR is monotonically incrementing.
119	 */
120	if (osmr[0] - oscr < MIN_OSCR_DELTA)
121		osmr[0] += MIN_OSCR_DELTA;
122
123	timer_writel(osmr[0], OSMR0);
124	timer_writel(osmr[1], OSMR1);
125	timer_writel(osmr[2], OSMR2);
126	timer_writel(osmr[3], OSMR3);
127	timer_writel(oier, OIER);
128	timer_writel(oscr, OSCR);
129}
130#else
131#define pxa_timer_suspend NULL
132#define pxa_timer_resume NULL
133#endif
134
135static struct clock_event_device ckevt_pxa_osmr0 = {
136	.name			= "osmr0",
137	.features		= CLOCK_EVT_FEAT_ONESHOT,
138	.rating			= 200,
139	.set_next_event		= pxa_osmr0_set_next_event,
140	.set_state_shutdown	= pxa_osmr0_shutdown,
141	.set_state_oneshot	= pxa_osmr0_shutdown,
142	.suspend		= pxa_timer_suspend,
143	.resume			= pxa_timer_resume,
144};
145
146static struct irqaction pxa_ost0_irq = {
147	.name		= "ost0",
148	.flags		= IRQF_TIMER | IRQF_IRQPOLL,
149	.handler	= pxa_ost0_interrupt,
150	.dev_id		= &ckevt_pxa_osmr0,
151};
152
153static void __init pxa_timer_common_init(int irq, unsigned long clock_tick_rate)
154{
155	timer_writel(0, OIER);
156	timer_writel(OSSR_M0 | OSSR_M1 | OSSR_M2 | OSSR_M3, OSSR);
157
158	sched_clock_register(pxa_read_sched_clock, 32, clock_tick_rate);
159
160	ckevt_pxa_osmr0.cpumask = cpumask_of(0);
161
162	setup_irq(irq, &pxa_ost0_irq);
163
164	clocksource_mmio_init(timer_base + OSCR, "oscr0", clock_tick_rate, 200,
165			      32, clocksource_mmio_readl_up);
166	clockevents_config_and_register(&ckevt_pxa_osmr0, clock_tick_rate,
167					MIN_OSCR_DELTA * 2, 0x7fffffff);
168}
169
170static void __init pxa_timer_dt_init(struct device_node *np)
171{
172	struct clk *clk;
173	int irq;
174
175	/* timer registers are shared with watchdog timer */
176	timer_base = of_iomap(np, 0);
177	if (!timer_base)
178		panic("%s: unable to map resource\n", np->name);
179
180	clk = of_clk_get(np, 0);
181	if (IS_ERR(clk)) {
182		pr_crit("%s: unable to get clk\n", np->name);
183		return;
184	}
185	clk_prepare_enable(clk);
186
187	/* we are only interested in OS-timer0 irq */
188	irq = irq_of_parse_and_map(np, 0);
189	if (irq <= 0) {
190		pr_crit("%s: unable to parse OS-timer0 irq\n", np->name);
191		return;
192	}
193
194	pxa_timer_common_init(irq, clk_get_rate(clk));
195}
196CLOCKSOURCE_OF_DECLARE(pxa_timer, "marvell,pxa-timer", pxa_timer_dt_init);
197
198/*
199 * Legacy timer init for non device-tree boards.
200 */
201void __init pxa_timer_nodt_init(int irq, void __iomem *base,
202	unsigned long clock_tick_rate)
203{
204	struct clk *clk;
205
206	timer_base = base;
207	clk = clk_get(NULL, "OSTIMER0");
208	if (clk && !IS_ERR(clk))
209		clk_prepare_enable(clk);
210	else
211		pr_crit("%s: unable to get clk\n", __func__);
212
213	pxa_timer_common_init(irq, clock_tick_rate);
214}
215