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1/*
2 * Copyright (C) 2015 ARM Limited
3 *
4 * Author: Vladimir Murzin <vladimir.murzin@arm.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License version 2 as
8 * published by the Free Software Foundation.
9 *
10 */
11
12#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
13
14#include <linux/clk.h>
15#include <linux/clockchips.h>
16#include <linux/clocksource.h>
17#include <linux/err.h>
18#include <linux/interrupt.h>
19#include <linux/io.h>
20#include <linux/irq.h>
21#include <linux/of_address.h>
22#include <linux/of.h>
23#include <linux/of_irq.h>
24#include <linux/sched_clock.h>
25#include <linux/slab.h>
26
27#define TIMER_CTRL 0x0
28#define TIMER_CTRL_ENABLE BIT(0)
29#define TIMER_CTRL_IE BIT(3)
30
31#define TIMER_VALUE 0x4
32#define TIMER_RELOAD 0x8
33#define TIMER_INT 0xc
34
35struct clockevent_mps2 {
36 void __iomem *reg;
37 u32 clock_count_per_tick;
38 struct clock_event_device clkevt;
39};
40
41static void __iomem *sched_clock_base;
42
43static u64 notrace mps2_sched_read(void)
44{
45 return ~readl_relaxed(sched_clock_base + TIMER_VALUE);
46}
47
48static inline struct clockevent_mps2 *to_mps2_clkevt(struct clock_event_device *c)
49{
50 return container_of(c, struct clockevent_mps2, clkevt);
51}
52
53static void clockevent_mps2_writel(u32 val, struct clock_event_device *c, u32 offset)
54{
55 writel_relaxed(val, to_mps2_clkevt(c)->reg + offset);
56}
57
58static int mps2_timer_shutdown(struct clock_event_device *ce)
59{
60 clockevent_mps2_writel(0, ce, TIMER_RELOAD);
61 clockevent_mps2_writel(0, ce, TIMER_CTRL);
62
63 return 0;
64}
65
66static int mps2_timer_set_next_event(unsigned long next, struct clock_event_device *ce)
67{
68 clockevent_mps2_writel(next, ce, TIMER_VALUE);
69 clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
70
71 return 0;
72}
73
74static int mps2_timer_set_periodic(struct clock_event_device *ce)
75{
76 u32 clock_count_per_tick = to_mps2_clkevt(ce)->clock_count_per_tick;
77
78 clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_RELOAD);
79 clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_VALUE);
80 clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
81
82 return 0;
83}
84
85static irqreturn_t mps2_timer_interrupt(int irq, void *dev_id)
86{
87 struct clockevent_mps2 *ce = dev_id;
88 u32 status = readl_relaxed(ce->reg + TIMER_INT);
89
90 if (!status) {
91 pr_warn("spurious interrupt\n");
92 return IRQ_NONE;
93 }
94
95 writel_relaxed(1, ce->reg + TIMER_INT);
96
97 ce->clkevt.event_handler(&ce->clkevt);
98
99 return IRQ_HANDLED;
100}
101
102static int __init mps2_clockevent_init(struct device_node *np)
103{
104 void __iomem *base;
105 struct clk *clk = NULL;
106 struct clockevent_mps2 *ce;
107 u32 rate;
108 int irq, ret;
109 const char *name = "mps2-clkevt";
110
111 ret = of_property_read_u32(np, "clock-frequency", &rate);
112 if (ret) {
113 clk = of_clk_get(np, 0);
114 if (IS_ERR(clk)) {
115 ret = PTR_ERR(clk);
116 pr_err("failed to get clock for clockevent: %d\n", ret);
117 goto out;
118 }
119
120 ret = clk_prepare_enable(clk);
121 if (ret) {
122 pr_err("failed to enable clock for clockevent: %d\n", ret);
123 goto out_clk_put;
124 }
125
126 rate = clk_get_rate(clk);
127 }
128
129 base = of_iomap(np, 0);
130 if (!base) {
131 ret = -EADDRNOTAVAIL;
132 pr_err("failed to map register for clockevent: %d\n", ret);
133 goto out_clk_disable;
134 }
135
136 irq = irq_of_parse_and_map(np, 0);
137 if (!irq) {
138 ret = -ENOENT;
139 pr_err("failed to get irq for clockevent: %d\n", ret);
140 goto out_iounmap;
141 }
142
143 ce = kzalloc(sizeof(*ce), GFP_KERNEL);
144 if (!ce) {
145 ret = -ENOMEM;
146 goto out_iounmap;
147 }
148
149 ce->reg = base;
150 ce->clock_count_per_tick = DIV_ROUND_CLOSEST(rate, HZ);
151 ce->clkevt.irq = irq;
152 ce->clkevt.name = name;
153 ce->clkevt.rating = 200;
154 ce->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
155 ce->clkevt.cpumask = cpu_possible_mask;
156 ce->clkevt.set_state_shutdown = mps2_timer_shutdown,
157 ce->clkevt.set_state_periodic = mps2_timer_set_periodic,
158 ce->clkevt.set_state_oneshot = mps2_timer_shutdown,
159 ce->clkevt.set_next_event = mps2_timer_set_next_event;
160
161 /* Ensure timer is disabled */
162 writel_relaxed(0, base + TIMER_CTRL);
163
164 ret = request_irq(irq, mps2_timer_interrupt, IRQF_TIMER, name, ce);
165 if (ret) {
166 pr_err("failed to request irq for clockevent: %d\n", ret);
167 goto out_kfree;
168 }
169
170 clockevents_config_and_register(&ce->clkevt, rate, 0xf, 0xffffffff);
171
172 return 0;
173
174out_kfree:
175 kfree(ce);
176out_iounmap:
177 iounmap(base);
178out_clk_disable:
179 /* clk_{disable, unprepare, put}() can handle NULL as a parameter */
180 clk_disable_unprepare(clk);
181out_clk_put:
182 clk_put(clk);
183out:
184 return ret;
185}
186
187static int __init mps2_clocksource_init(struct device_node *np)
188{
189 void __iomem *base;
190 struct clk *clk = NULL;
191 u32 rate;
192 int ret;
193 const char *name = "mps2-clksrc";
194
195 ret = of_property_read_u32(np, "clock-frequency", &rate);
196 if (ret) {
197 clk = of_clk_get(np, 0);
198 if (IS_ERR(clk)) {
199 ret = PTR_ERR(clk);
200 pr_err("failed to get clock for clocksource: %d\n", ret);
201 goto out;
202 }
203
204 ret = clk_prepare_enable(clk);
205 if (ret) {
206 pr_err("failed to enable clock for clocksource: %d\n", ret);
207 goto out_clk_put;
208 }
209
210 rate = clk_get_rate(clk);
211 }
212
213 base = of_iomap(np, 0);
214 if (!base) {
215 ret = -EADDRNOTAVAIL;
216 pr_err("failed to map register for clocksource: %d\n", ret);
217 goto out_clk_disable;
218 }
219
220 /* Ensure timer is disabled */
221 writel_relaxed(0, base + TIMER_CTRL);
222
223 /* ... and set it up as free-running clocksource */
224 writel_relaxed(0xffffffff, base + TIMER_VALUE);
225 writel_relaxed(0xffffffff, base + TIMER_RELOAD);
226
227 writel_relaxed(TIMER_CTRL_ENABLE, base + TIMER_CTRL);
228
229 ret = clocksource_mmio_init(base + TIMER_VALUE, name,
230 rate, 200, 32,
231 clocksource_mmio_readl_down);
232 if (ret) {
233 pr_err("failed to init clocksource: %d\n", ret);
234 goto out_iounmap;
235 }
236
237 sched_clock_base = base;
238 sched_clock_register(mps2_sched_read, 32, rate);
239
240 return 0;
241
242out_iounmap:
243 iounmap(base);
244out_clk_disable:
245 /* clk_{disable, unprepare, put}() can handle NULL as a parameter */
246 clk_disable_unprepare(clk);
247out_clk_put:
248 clk_put(clk);
249out:
250 return ret;
251}
252
253static int __init mps2_timer_init(struct device_node *np)
254{
255 static int has_clocksource, has_clockevent;
256 int ret;
257
258 if (!has_clocksource) {
259 ret = mps2_clocksource_init(np);
260 if (!ret) {
261 has_clocksource = 1;
262 return 0;
263 }
264 }
265
266 if (!has_clockevent) {
267 ret = mps2_clockevent_init(np);
268 if (!ret) {
269 has_clockevent = 1;
270 return 0;
271 }
272 }
273
274 return 0;
275}
276
277TIMER_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init);
278

Warning: That file was not part of the compilation database. It may have many parsing errors.