tjh.dev
Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
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);