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273 lines · 6.0 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2015 ARM Limited
4 *
5 * Author: Vladimir Murzin <[email protected]>
6 */
7
8#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
9
10#include <linux/clk.h>
11#include <linux/clockchips.h>
12#include <linux/clocksource.h>
13#include <linux/err.h>
14#include <linux/interrupt.h>
15#include <linux/io.h>
16#include <linux/irq.h>
17#include <linux/of_address.h>
18#include <linux/of.h>
19#include <linux/of_irq.h>
20#include <linux/sched_clock.h>
21#include <linux/slab.h>
22
23#define TIMER_CTRL 0x0
24#define TIMER_CTRL_ENABLE BIT(0)
25#define TIMER_CTRL_IE BIT(3)
26
27#define TIMER_VALUE 0x4
28#define TIMER_RELOAD 0x8
29#define TIMER_INT 0xc
30
31struct clockevent_mps2 {
32 void __iomem *reg;
33 u32 clock_count_per_tick;
34 struct clock_event_device clkevt;
35};
36
37static void __iomem *sched_clock_base;
38
39static u64 notrace mps2_sched_read(void)
40{
41 return ~readl_relaxed(sched_clock_base + TIMER_VALUE);
42}
43
44static inline struct clockevent_mps2 *to_mps2_clkevt(struct clock_event_device *c)
45{
46 return container_of(c, struct clockevent_mps2, clkevt);
47}
48
49static void clockevent_mps2_writel(u32 val, struct clock_event_device *c, u32 offset)
50{
51 writel_relaxed(val, to_mps2_clkevt(c)->reg + offset);
52}
53
54static int mps2_timer_shutdown(struct clock_event_device *ce)
55{
56 clockevent_mps2_writel(0, ce, TIMER_RELOAD);
57 clockevent_mps2_writel(0, ce, TIMER_CTRL);
58
59 return 0;
60}
61
62static int mps2_timer_set_next_event(unsigned long next, struct clock_event_device *ce)
63{
64 clockevent_mps2_writel(next, ce, TIMER_VALUE);
65 clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
66
67 return 0;
68}
69
70static int mps2_timer_set_periodic(struct clock_event_device *ce)
71{
72 u32 clock_count_per_tick = to_mps2_clkevt(ce)->clock_count_per_tick;
73
74 clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_RELOAD);
75 clockevent_mps2_writel(clock_count_per_tick, ce, TIMER_VALUE);
76 clockevent_mps2_writel(TIMER_CTRL_IE | TIMER_CTRL_ENABLE, ce, TIMER_CTRL);
77
78 return 0;
79}
80
81static irqreturn_t mps2_timer_interrupt(int irq, void *dev_id)
82{
83 struct clockevent_mps2 *ce = dev_id;
84 u32 status = readl_relaxed(ce->reg + TIMER_INT);
85
86 if (!status) {
87 pr_warn("spurious interrupt\n");
88 return IRQ_NONE;
89 }
90
91 writel_relaxed(1, ce->reg + TIMER_INT);
92
93 ce->clkevt.event_handler(&ce->clkevt);
94
95 return IRQ_HANDLED;
96}
97
98static int __init mps2_clockevent_init(struct device_node *np)
99{
100 void __iomem *base;
101 struct clk *clk = NULL;
102 struct clockevent_mps2 *ce;
103 u32 rate;
104 int irq, ret;
105 const char *name = "mps2-clkevt";
106
107 ret = of_property_read_u32(np, "clock-frequency", &rate);
108 if (ret) {
109 clk = of_clk_get(np, 0);
110 if (IS_ERR(clk)) {
111 ret = PTR_ERR(clk);
112 pr_err("failed to get clock for clockevent: %d\n", ret);
113 goto out;
114 }
115
116 ret = clk_prepare_enable(clk);
117 if (ret) {
118 pr_err("failed to enable clock for clockevent: %d\n", ret);
119 goto out_clk_put;
120 }
121
122 rate = clk_get_rate(clk);
123 }
124
125 base = of_iomap(np, 0);
126 if (!base) {
127 ret = -EADDRNOTAVAIL;
128 pr_err("failed to map register for clockevent: %d\n", ret);
129 goto out_clk_disable;
130 }
131
132 irq = irq_of_parse_and_map(np, 0);
133 if (!irq) {
134 ret = -ENOENT;
135 pr_err("failed to get irq for clockevent: %d\n", ret);
136 goto out_iounmap;
137 }
138
139 ce = kzalloc_obj(*ce);
140 if (!ce) {
141 ret = -ENOMEM;
142 goto out_iounmap;
143 }
144
145 ce->reg = base;
146 ce->clock_count_per_tick = DIV_ROUND_CLOSEST(rate, HZ);
147 ce->clkevt.irq = irq;
148 ce->clkevt.name = name;
149 ce->clkevt.rating = 200;
150 ce->clkevt.features = CLOCK_EVT_FEAT_PERIODIC | CLOCK_EVT_FEAT_ONESHOT;
151 ce->clkevt.cpumask = cpu_possible_mask;
152 ce->clkevt.set_state_shutdown = mps2_timer_shutdown;
153 ce->clkevt.set_state_periodic = mps2_timer_set_periodic;
154 ce->clkevt.set_state_oneshot = mps2_timer_shutdown;
155 ce->clkevt.set_next_event = mps2_timer_set_next_event;
156
157 /* Ensure timer is disabled */
158 writel_relaxed(0, base + TIMER_CTRL);
159
160 ret = request_irq(irq, mps2_timer_interrupt, IRQF_TIMER, name, ce);
161 if (ret) {
162 pr_err("failed to request irq for clockevent: %d\n", ret);
163 goto out_kfree;
164 }
165
166 clockevents_config_and_register(&ce->clkevt, rate, 0xf, 0xffffffff);
167
168 return 0;
169
170out_kfree:
171 kfree(ce);
172out_iounmap:
173 iounmap(base);
174out_clk_disable:
175 /* clk_{disable, unprepare, put}() can handle NULL as a parameter */
176 clk_disable_unprepare(clk);
177out_clk_put:
178 clk_put(clk);
179out:
180 return ret;
181}
182
183static int __init mps2_clocksource_init(struct device_node *np)
184{
185 void __iomem *base;
186 struct clk *clk = NULL;
187 u32 rate;
188 int ret;
189 const char *name = "mps2-clksrc";
190
191 ret = of_property_read_u32(np, "clock-frequency", &rate);
192 if (ret) {
193 clk = of_clk_get(np, 0);
194 if (IS_ERR(clk)) {
195 ret = PTR_ERR(clk);
196 pr_err("failed to get clock for clocksource: %d\n", ret);
197 goto out;
198 }
199
200 ret = clk_prepare_enable(clk);
201 if (ret) {
202 pr_err("failed to enable clock for clocksource: %d\n", ret);
203 goto out_clk_put;
204 }
205
206 rate = clk_get_rate(clk);
207 }
208
209 base = of_iomap(np, 0);
210 if (!base) {
211 ret = -EADDRNOTAVAIL;
212 pr_err("failed to map register for clocksource: %d\n", ret);
213 goto out_clk_disable;
214 }
215
216 /* Ensure timer is disabled */
217 writel_relaxed(0, base + TIMER_CTRL);
218
219 /* ... and set it up as free-running clocksource */
220 writel_relaxed(0xffffffff, base + TIMER_VALUE);
221 writel_relaxed(0xffffffff, base + TIMER_RELOAD);
222
223 writel_relaxed(TIMER_CTRL_ENABLE, base + TIMER_CTRL);
224
225 ret = clocksource_mmio_init(base + TIMER_VALUE, name,
226 rate, 200, 32,
227 clocksource_mmio_readl_down);
228 if (ret) {
229 pr_err("failed to init clocksource: %d\n", ret);
230 goto out_iounmap;
231 }
232
233 sched_clock_base = base;
234 sched_clock_register(mps2_sched_read, 32, rate);
235
236 return 0;
237
238out_iounmap:
239 iounmap(base);
240out_clk_disable:
241 /* clk_{disable, unprepare, put}() can handle NULL as a parameter */
242 clk_disable_unprepare(clk);
243out_clk_put:
244 clk_put(clk);
245out:
246 return ret;
247}
248
249static int __init mps2_timer_init(struct device_node *np)
250{
251 static int has_clocksource, has_clockevent;
252 int ret;
253
254 if (!has_clocksource) {
255 ret = mps2_clocksource_init(np);
256 if (!ret) {
257 has_clocksource = 1;
258 return 0;
259 }
260 }
261
262 if (!has_clockevent) {
263 ret = mps2_clockevent_init(np);
264 if (!ret) {
265 has_clockevent = 1;
266 return 0;
267 }
268 }
269
270 return 0;
271}
272
273TIMER_OF_DECLARE(mps2_timer, "arm,mps2-timer", mps2_timer_init);