1/*
  2 * Marvell Orion SoC timer handling.
  3 *
  4 * Sebastian Hesselbarth <sebastian.hesselbarth@gmail.com>
  5 *
  6 * This file is licensed under the terms of the GNU General Public
  7 * License version 2.  This program is licensed "as is" without any
  8 * warranty of any kind, whether express or implied.
  9 *
 10 * Timer 0 is used as free-running clocksource, while timer 1 is
 11 * used as clock_event_device.
 12 */
 13
 14#include <linux/kernel.h>
 15#include <linux/bitops.h>
 16#include <linux/clk.h>
 17#include <linux/clockchips.h>
 18#include <linux/interrupt.h>
 19#include <linux/of_address.h>
 20#include <linux/of_irq.h>
 21#include <linux/spinlock.h>
 22#include <linux/sched_clock.h>
 23
 24#define TIMER_CTRL		0x00
 25#define  TIMER0_EN		BIT(0)
 26#define  TIMER0_RELOAD_EN	BIT(1)
 27#define  TIMER1_EN		BIT(2)
 28#define  TIMER1_RELOAD_EN	BIT(3)
 29#define TIMER0_RELOAD		0x10
 30#define TIMER0_VAL		0x14
 31#define TIMER1_RELOAD		0x18
 32#define TIMER1_VAL		0x1c
 33
 34#define ORION_ONESHOT_MIN	1
 35#define ORION_ONESHOT_MAX	0xfffffffe
 36
 37static void __iomem *timer_base;
 38
 39/*
 40 * Free-running clocksource handling.
 41 */
 42static u64 notrace orion_read_sched_clock(void)
 43{
 44	return ~readl(timer_base + TIMER0_VAL);
 45}
 46
 47/*
 48 * Clockevent handling.
 49 */
 50static u32 ticks_per_jiffy;
 51
 52static int orion_clkevt_next_event(unsigned long delta,
 53				   struct clock_event_device *dev)
 54{
 55	/* setup and enable one-shot timer */
 56	writel(delta, timer_base + TIMER1_VAL);
 57	atomic_io_modify(timer_base + TIMER_CTRL,
 58		TIMER1_RELOAD_EN | TIMER1_EN, TIMER1_EN);
 59
 60	return 0;
 61}
 62
 63static int orion_clkevt_shutdown(struct clock_event_device *dev)
 64{
 65	/* disable timer */
 66	atomic_io_modify(timer_base + TIMER_CTRL,
 67			 TIMER1_RELOAD_EN | TIMER1_EN, 0);
 68	return 0;
 69}
 70
 71static int orion_clkevt_set_periodic(struct clock_event_device *dev)
 72{
 73	/* setup and enable periodic timer at 1/HZ intervals */
 74	writel(ticks_per_jiffy - 1, timer_base + TIMER1_RELOAD);
 75	writel(ticks_per_jiffy - 1, timer_base + TIMER1_VAL);
 76	atomic_io_modify(timer_base + TIMER_CTRL,
 77			 TIMER1_RELOAD_EN | TIMER1_EN,
 78			 TIMER1_RELOAD_EN | TIMER1_EN);
 79	return 0;
 80}
 81
 82static struct clock_event_device orion_clkevt = {
 83	.name			= "orion_event",
 84	.features		= CLOCK_EVT_FEAT_ONESHOT |
 85				  CLOCK_EVT_FEAT_PERIODIC,
 86	.shift			= 32,
 87	.rating			= 300,
 88	.set_next_event		= orion_clkevt_next_event,
 89	.set_state_shutdown	= orion_clkevt_shutdown,
 90	.set_state_periodic	= orion_clkevt_set_periodic,
 91	.set_state_oneshot	= orion_clkevt_shutdown,
 92	.tick_resume		= orion_clkevt_shutdown,
 93};
 94
 95static irqreturn_t orion_clkevt_irq_handler(int irq, void *dev_id)
 96{
 97	orion_clkevt.event_handler(&orion_clkevt);
 98	return IRQ_HANDLED;
 99}
100
101static struct irqaction orion_clkevt_irq = {
102	.name		= "orion_event",
103	.flags		= IRQF_TIMER,
104	.handler	= orion_clkevt_irq_handler,
105};
106
107static void __init orion_timer_init(struct device_node *np)
108{
109	struct clk *clk;
110	int irq;
111
112	/* timer registers are shared with watchdog timer */
113	timer_base = of_iomap(np, 0);
114	if (!timer_base)
115		panic("%s: unable to map resource\n", np->name);
116
117	clk = of_clk_get(np, 0);
118	if (IS_ERR(clk))
119		panic("%s: unable to get clk\n", np->name);
120	clk_prepare_enable(clk);
121
122	/* we are only interested in timer1 irq */
123	irq = irq_of_parse_and_map(np, 1);
124	if (irq <= 0)
125		panic("%s: unable to parse timer1 irq\n", np->name);
126
127	/* setup timer0 as free-running clocksource */
128	writel(~0, timer_base + TIMER0_VAL);
129	writel(~0, timer_base + TIMER0_RELOAD);
130	atomic_io_modify(timer_base + TIMER_CTRL,
131		TIMER0_RELOAD_EN | TIMER0_EN,
132		TIMER0_RELOAD_EN | TIMER0_EN);
133	clocksource_mmio_init(timer_base + TIMER0_VAL, "orion_clocksource",
134			      clk_get_rate(clk), 300, 32,
135			      clocksource_mmio_readl_down);
136	sched_clock_register(orion_read_sched_clock, 32, clk_get_rate(clk));
137
138	/* setup timer1 as clockevent timer */
139	if (setup_irq(irq, &orion_clkevt_irq))
140		panic("%s: unable to setup irq\n", np->name);
141
142	ticks_per_jiffy = (clk_get_rate(clk) + HZ/2) / HZ;
143	orion_clkevt.cpumask = cpumask_of(0);
144	orion_clkevt.irq = irq;
145	clockevents_config_and_register(&orion_clkevt, clk_get_rate(clk),
146					ORION_ONESHOT_MIN, ORION_ONESHOT_MAX);
147}
148CLOCKSOURCE_OF_DECLARE(orion_timer, "marvell,orion-timer", orion_timer_init);