1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3 * Integrator/AP timer driver
4 * Copyright (C) 2000-2003 Deep Blue Solutions Ltd
5 * Copyright (c) 2014, Linaro Limited
6 */
7
8 #include <linux/clk.h>
9 #include <linux/clocksource.h>
10 #include <linux/of.h>
11 #include <linux/of_irq.h>
12 #include <linux/of_address.h>
13 #include <linux/clockchips.h>
14 #include <linux/interrupt.h>
15 #include <linux/sched_clock.h>
16
17 #include "timer-sp.h"
18
19 static void __iomem * sched_clk_base;
20
integrator_read_sched_clock(void)21 static u64 notrace integrator_read_sched_clock(void)
22 {
23 return -readl(sched_clk_base + TIMER_VALUE);
24 }
25
integrator_clocksource_init(unsigned long inrate,void __iomem * base)26 static int __init integrator_clocksource_init(unsigned long inrate,
27 void __iomem *base)
28 {
29 u32 ctrl = TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC;
30 unsigned long rate = inrate;
31 int ret;
32
33 if (rate >= 1500000) {
34 rate /= 16;
35 ctrl |= TIMER_CTRL_DIV16;
36 }
37
38 writel(0xffff, base + TIMER_LOAD);
39 writel(ctrl, base + TIMER_CTRL);
40
41 ret = clocksource_mmio_init(base + TIMER_VALUE, "timer2",
42 rate, 200, 16, clocksource_mmio_readl_down);
43 if (ret)
44 return ret;
45
46 sched_clk_base = base;
47 sched_clock_register(integrator_read_sched_clock, 16, rate);
48
49 return 0;
50 }
51
52 static unsigned long timer_reload;
53 static void __iomem * clkevt_base;
54
55 /*
56 * IRQ handler for the timer
57 */
integrator_timer_interrupt(int irq,void * dev_id)58 static irqreturn_t integrator_timer_interrupt(int irq, void *dev_id)
59 {
60 struct clock_event_device *evt = dev_id;
61
62 /* clear the interrupt */
63 writel(1, clkevt_base + TIMER_INTCLR);
64
65 evt->event_handler(evt);
66
67 return IRQ_HANDLED;
68 }
69
clkevt_shutdown(struct clock_event_device * evt)70 static int clkevt_shutdown(struct clock_event_device *evt)
71 {
72 u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE;
73
74 /* Disable timer */
75 writel(ctrl, clkevt_base + TIMER_CTRL);
76 return 0;
77 }
78
clkevt_set_oneshot(struct clock_event_device * evt)79 static int clkevt_set_oneshot(struct clock_event_device *evt)
80 {
81 u32 ctrl = readl(clkevt_base + TIMER_CTRL) &
82 ~(TIMER_CTRL_ENABLE | TIMER_CTRL_PERIODIC);
83
84 /* Leave the timer disabled, .set_next_event will enable it */
85 writel(ctrl, clkevt_base + TIMER_CTRL);
86 return 0;
87 }
88
clkevt_set_periodic(struct clock_event_device * evt)89 static int clkevt_set_periodic(struct clock_event_device *evt)
90 {
91 u32 ctrl = readl(clkevt_base + TIMER_CTRL) & ~TIMER_CTRL_ENABLE;
92
93 /* Disable timer */
94 writel(ctrl, clkevt_base + TIMER_CTRL);
95
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);
100 return 0;
101 }
102
clkevt_set_next_event(unsigned long next,struct clock_event_device * evt)103 static int clkevt_set_next_event(unsigned long next, struct clock_event_device *evt)
104 {
105 unsigned long ctrl = readl(clkevt_base + TIMER_CTRL);
106
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);
110
111 return 0;
112 }
113
114 static struct clock_event_device integrator_clockevent = {
115 .name = "timer1",
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,
123 .rating = 300,
124 };
125
integrator_clockevent_init(unsigned long inrate,void __iomem * base,int irq)126 static int integrator_clockevent_init(unsigned long inrate,
127 void __iomem *base, int irq)
128 {
129 unsigned long rate = inrate;
130 unsigned int ctrl = 0;
131 int ret;
132
133 clkevt_base = base;
134 /* Calculate and program a divisor */
135 if (rate > 0x100000 * HZ) {
136 rate /= 256;
137 ctrl |= TIMER_CTRL_DIV256;
138 } else if (rate > 0x10000 * HZ) {
139 rate /= 16;
140 ctrl |= TIMER_CTRL_DIV16;
141 }
142 timer_reload = rate / HZ;
143 writel(ctrl, clkevt_base + TIMER_CTRL);
144
145 ret = request_irq(irq, integrator_timer_interrupt,
146 IRQF_TIMER | IRQF_IRQPOLL, "timer",
147 &integrator_clockevent);
148 if (ret)
149 return ret;
150
151 clockevents_config_and_register(&integrator_clockevent,
152 rate,
153 1,
154 0xffffU);
155 return 0;
156 }
157
integrator_ap_timer_init_of(struct device_node * node)158 static int __init integrator_ap_timer_init_of(struct device_node *node)
159 {
160 const char *path;
161 void __iomem *base;
162 int err;
163 int irq;
164 struct clk *clk;
165 unsigned long rate;
166 struct device_node *alias_node;
167
168 base = of_io_request_and_map(node, 0, "integrator-timer");
169 if (IS_ERR(base))
170 return PTR_ERR(base);
171
172 clk = of_clk_get(node, 0);
173 if (IS_ERR(clk)) {
174 pr_err("No clock for %pOFn\n", node);
175 return PTR_ERR(clk);
176 }
177 clk_prepare_enable(clk);
178 rate = clk_get_rate(clk);
179 writel(0, base + TIMER_CTRL);
180
181 err = of_property_read_string(of_aliases,
182 "arm,timer-primary", &path);
183 if (err) {
184 pr_warn("Failed to read property\n");
185 return err;
186 }
187
188 alias_node = of_find_node_by_path(path);
189
190 /*
191 * The pointer is used as an identifier not as a pointer, we
192 * can drop the refcount on the of__node immediately after
193 * getting it.
194 */
195 of_node_put(alias_node);
196
197 if (node == alias_node)
198 /* The primary timer lacks IRQ, use as clocksource */
199 return integrator_clocksource_init(rate, base);
200
201 err = of_property_read_string(of_aliases,
202 "arm,timer-secondary", &path);
203 if (err) {
204 pr_warn("Failed to read property\n");
205 return err;
206 }
207
208 alias_node = of_find_node_by_path(path);
209
210 of_node_put(alias_node);
211
212 if (node == alias_node) {
213 /* The secondary timer will drive the clock event */
214 irq = irq_of_parse_and_map(node, 0);
215 return integrator_clockevent_init(rate, base, irq);
216 }
217
218 pr_info("Timer @%p unused\n", base);
219 clk_disable_unprepare(clk);
220
221 return 0;
222 }
223
224 TIMER_OF_DECLARE(integrator_ap_timer, "arm,integrator-timer",
225 integrator_ap_timer_init_of);
226