1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Integrator/AP timer driver
4 * Copyright (C) 2000-2003 Deep Blue Solutions Ltd
5 * Copyright (c) 2014, Linaro Limited
9 #include <linux/clocksource.h>
10 #include <linux/of_irq.h>
11 #include <linux/of_address.h>
12 #include <linux/of_platform.h>
13 #include <linux/clockchips.h>
14 #include <linux/interrupt.h>
15 #include <linux/sched_clock.h>
19 static void __iomem * sched_clk_base;
21 static u64 notrace integrator_read_sched_clock(void)
23 return -readl(sched_clk_base + TIMER_VALUE);
26 static int __init integrator_clocksource_init(unsigned long inrate,
29 u32 ctrl = TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC;
30 unsigned long rate = inrate;
33 if (rate >= 1500000) {
35 ctrl |= TIMER_CTRL_DIV16;
38 writel(0xffff, base + TIMER_LOAD);
39 writel(ctrl, base + TIMER_CTRL);
41 ret = clocksource_mmio_init(base + TIMER_VALUE, "timer2",
42 rate, 200, 16, clocksource_mmio_readl_down);
46 sched_clk_base = base;
47 sched_clock_register(integrator_read_sched_clock, 16, rate);
52 static unsigned long timer_reload;
53 static void __iomem * clkevt_base;
56 * IRQ handler for the timer
58 static irqreturn_t integrator_timer_interrupt(int irq, void *dev_id)
60 struct clock_event_device *evt = dev_id;
62 /* clear the interrupt */
63 writel(1, clkevt_base + TIMER_INTCLR);
65 evt->event_handler(evt);
70 static int clkevt_shutdown(struct clock_event_device *evt)
72 u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE;
75 writel(ctrl, clkevt_base + TIMER_CTRL);
79 static int clkevt_set_oneshot(struct clock_event_device *evt)
81 u32 ctrl = readl(clkevt_base + TIMER_CTRL) &
82 ~(TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC);
84 /* Leave the timer disabled, .set_next_event will enable it */
85 writel(ctrl, clkevt_base + TIMER_CTRL);
89 static int clkevt_set_periodic(struct clock_event_device *evt)
91 u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE;
94 writel(ctrl, clkevt_base + TIMER_CTRL);
96 /* Enable the timer and start the periodic tick */
97 writel(timer_reload, clkevt_base + TIMER_LOAD);
98 ctrl |= TIMER_CTRL_PERIODIC | TIMER_CTRL_ENABLE;
99 writel(ctrl, clkevt_base + TIMER_CTRL);
103 static int clkevt_set_next_event(unsigned long next, struct clock_event_device *evt)
105 unsigned long ctrl = readl(clkevt_base + TIMER_CTRL);
107 writel(ctrl & ~TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL);
108 writel(next, clkevt_base + TIMER_LOAD);
109 writel(ctrl | TIMER_CTRL_ENABLE, clkevt_base + TIMER_CTRL);
114 static struct clock_event_device integrator_clockevent = {
116 .features = CLOCK_EVT_FEAT_PERIODIC |
117 CLOCK_EVT_FEAT_ONESHOT,
118 .set_state_shutdown = clkevt_shutdown,
119 .set_state_periodic = clkevt_set_periodic,
120 .set_state_oneshot = clkevt_set_oneshot,
121 .tick_resume = clkevt_shutdown,
122 .set_next_event = clkevt_set_next_event,
126 static struct irqaction integrator_timer_irq = {
128 .flags = IRQF_TIMER | IRQF_IRQPOLL,
129 .handler = integrator_timer_interrupt,
130 .dev_id = &integrator_clockevent,
133 static int integrator_clockevent_init(unsigned long inrate,
134 void __iomem *base, int irq)
136 unsigned long rate = inrate;
137 unsigned int ctrl = 0;
141 /* Calculate and program a divisor */
142 if (rate > 0x100000 * HZ) {
144 ctrl |= TIMER_CTRL_DIV256;
145 } else if (rate > 0x10000 * HZ) {
147 ctrl |= TIMER_CTRL_DIV16;
149 timer_reload = rate / HZ;
150 writel(ctrl, clkevt_base + TIMER_CTRL);
152 ret = setup_irq(irq, &integrator_timer_irq);
156 clockevents_config_and_register(&integrator_clockevent,
163 static int __init integrator_ap_timer_init_of(struct device_node *node)
171 struct device_node *alias_node;
173 base = of_io_request_and_map(node, 0, "integrator-timer");
175 return PTR_ERR(base);
177 clk = of_clk_get(node, 0);
179 pr_err("No clock for %pOFn\n", node);
182 clk_prepare_enable(clk);
183 rate = clk_get_rate(clk);
184 writel(0, base + TIMER_CTRL);
186 err = of_property_read_string(of_aliases,
187 "arm,timer-primary", &path);
189 pr_warn("Failed to read property\n");
193 alias_node = of_find_node_by_path(path);
196 * The pointer is used as an identifier not as a pointer, we
197 * can drop the refcount on the of__node immediately after
200 of_node_put(alias_node);
202 if (node == alias_node)
203 /* The primary timer lacks IRQ, use as clocksource */
204 return integrator_clocksource_init(rate, base);
206 err = of_property_read_string(of_aliases,
207 "arm,timer-secondary", &path);
209 pr_warn("Failed to read property\n");
213 alias_node = of_find_node_by_path(path);
215 of_node_put(alias_node);
217 if (node == alias_node) {
218 /* The secondary timer will drive the clock event */
219 irq = irq_of_parse_and_map(node, 0);
220 return integrator_clockevent_init(rate, base, irq);
223 pr_info("Timer @%p unused\n", base);
224 clk_disable_unprepare(clk);
229 TIMER_OF_DECLARE(integrator_ap_timer, "arm,integrator-timer",
230 integrator_ap_timer_init_of);