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363 lines · 8.2 KiB

1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Emma Mobile Timer Support - STI
4 *
5 * Copyright (C) 2012 Magnus Damm
6 */
7
8#include <linux/init.h>
9#include <linux/platform_device.h>
10#include <linux/spinlock.h>
11#include <linux/interrupt.h>
12#include <linux/ioport.h>
13#include <linux/io.h>
14#include <linux/clk.h>
15#include <linux/irq.h>
16#include <linux/err.h>
17#include <linux/delay.h>
18#include <linux/clocksource.h>
19#include <linux/clockchips.h>
20#include <linux/slab.h>
21#include <linux/module.h>
22
23enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR };
24
25struct em_sti_priv {
26 void __iomem *base;
27 struct clk *clk;
28 struct platform_device *pdev;
29 unsigned int active[USER_NR];
30 unsigned long rate;
31 raw_spinlock_t lock;
32 struct clock_event_device ced;
33 struct clocksource cs;
34};
35
36#define STI_CONTROL 0x00
37#define STI_COMPA_H 0x10
38#define STI_COMPA_L 0x14
39#define STI_COMPB_H 0x18
40#define STI_COMPB_L 0x1c
41#define STI_COUNT_H 0x20
42#define STI_COUNT_L 0x24
43#define STI_COUNT_RAW_H 0x28
44#define STI_COUNT_RAW_L 0x2c
45#define STI_SET_H 0x30
46#define STI_SET_L 0x34
47#define STI_INTSTATUS 0x40
48#define STI_INTRAWSTATUS 0x44
49#define STI_INTENSET 0x48
50#define STI_INTENCLR 0x4c
51#define STI_INTFFCLR 0x50
52
53static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs)
54{
55 return ioread32(p->base + offs);
56}
57
58static inline void em_sti_write(struct em_sti_priv *p, int offs,
59 unsigned long value)
60{
61 iowrite32(value, p->base + offs);
62}
63
64static int em_sti_enable(struct em_sti_priv *p)
65{
66 int ret;
67
68 /* enable clock */
69 ret = clk_enable(p->clk);
70 if (ret) {
71 dev_err(&p->pdev->dev, "cannot enable clock\n");
72 return ret;
73 }
74
75 /* reset the counter */
76 em_sti_write(p, STI_SET_H, 0x40000000);
77 em_sti_write(p, STI_SET_L, 0x00000000);
78
79 /* mask and clear pending interrupts */
80 em_sti_write(p, STI_INTENCLR, 3);
81 em_sti_write(p, STI_INTFFCLR, 3);
82
83 /* enable updates of counter registers */
84 em_sti_write(p, STI_CONTROL, 1);
85
86 return 0;
87}
88
89static void em_sti_disable(struct em_sti_priv *p)
90{
91 /* mask interrupts */
92 em_sti_write(p, STI_INTENCLR, 3);
93
94 /* stop clock */
95 clk_disable(p->clk);
96}
97
98static u64 em_sti_count(struct em_sti_priv *p)
99{
100 u64 ticks;
101 unsigned long flags;
102
103 /* the STI hardware buffers the 48-bit count, but to
104 * break it out into two 32-bit access the registers
105 * must be accessed in a certain order.
106 * Always read STI_COUNT_H before STI_COUNT_L.
107 */
108 raw_spin_lock_irqsave(&p->lock, flags);
109 ticks = (u64)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32;
110 ticks |= em_sti_read(p, STI_COUNT_L);
111 raw_spin_unlock_irqrestore(&p->lock, flags);
112
113 return ticks;
114}
115
116static u64 em_sti_set_next(struct em_sti_priv *p, u64 next)
117{
118 unsigned long flags;
119
120 raw_spin_lock_irqsave(&p->lock, flags);
121
122 /* mask compare A interrupt */
123 em_sti_write(p, STI_INTENCLR, 1);
124
125 /* update compare A value */
126 em_sti_write(p, STI_COMPA_H, next >> 32);
127 em_sti_write(p, STI_COMPA_L, next & 0xffffffff);
128
129 /* clear compare A interrupt source */
130 em_sti_write(p, STI_INTFFCLR, 1);
131
132 /* unmask compare A interrupt */
133 em_sti_write(p, STI_INTENSET, 1);
134
135 raw_spin_unlock_irqrestore(&p->lock, flags);
136
137 return next;
138}
139
140static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
141{
142 struct em_sti_priv *p = dev_id;
143
144 p->ced.event_handler(&p->ced);
145 return IRQ_HANDLED;
146}
147
148static int em_sti_start(struct em_sti_priv *p, unsigned int user)
149{
150 unsigned long flags;
151 int used_before;
152 int ret = 0;
153
154 raw_spin_lock_irqsave(&p->lock, flags);
155 used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
156 if (!used_before)
157 ret = em_sti_enable(p);
158
159 if (!ret)
160 p->active[user] = 1;
161 raw_spin_unlock_irqrestore(&p->lock, flags);
162
163 return ret;
164}
165
166static void em_sti_stop(struct em_sti_priv *p, unsigned int user)
167{
168 unsigned long flags;
169 int used_before, used_after;
170
171 raw_spin_lock_irqsave(&p->lock, flags);
172 used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
173 p->active[user] = 0;
174 used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
175
176 if (used_before && !used_after)
177 em_sti_disable(p);
178 raw_spin_unlock_irqrestore(&p->lock, flags);
179}
180
181static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
182{
183 return container_of(cs, struct em_sti_priv, cs);
184}
185
186static u64 em_sti_clocksource_read(struct clocksource *cs)
187{
188 return em_sti_count(cs_to_em_sti(cs));
189}
190
191static int em_sti_clocksource_enable(struct clocksource *cs)
192{
193 struct em_sti_priv *p = cs_to_em_sti(cs);
194
195 return em_sti_start(p, USER_CLOCKSOURCE);
196}
197
198static void em_sti_clocksource_disable(struct clocksource *cs)
199{
200 em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
201}
202
203static void em_sti_clocksource_resume(struct clocksource *cs)
204{
205 em_sti_clocksource_enable(cs);
206}
207
208static int em_sti_register_clocksource(struct em_sti_priv *p)
209{
210 struct clocksource *cs = &p->cs;
211
212 cs->name = dev_name(&p->pdev->dev);
213 cs->rating = 200;
214 cs->read = em_sti_clocksource_read;
215 cs->enable = em_sti_clocksource_enable;
216 cs->disable = em_sti_clocksource_disable;
217 cs->suspend = em_sti_clocksource_disable;
218 cs->resume = em_sti_clocksource_resume;
219 cs->mask = CLOCKSOURCE_MASK(48);
220 cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
221
222 dev_info(&p->pdev->dev, "used as clock source\n");
223
224 clocksource_register_hz(cs, p->rate);
225 return 0;
226}
227
228static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
229{
230 return container_of(ced, struct em_sti_priv, ced);
231}
232
233static int em_sti_clock_event_shutdown(struct clock_event_device *ced)
234{
235 struct em_sti_priv *p = ced_to_em_sti(ced);
236 em_sti_stop(p, USER_CLOCKEVENT);
237 return 0;
238}
239
240static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced)
241{
242 struct em_sti_priv *p = ced_to_em_sti(ced);
243
244 dev_info(&p->pdev->dev, "used for oneshot clock events\n");
245 em_sti_start(p, USER_CLOCKEVENT);
246 return 0;
247}
248
249static int em_sti_clock_event_next(unsigned long delta,
250 struct clock_event_device *ced)
251{
252 struct em_sti_priv *p = ced_to_em_sti(ced);
253 u64 next;
254 int safe;
255
256 next = em_sti_set_next(p, em_sti_count(p) + delta);
257 safe = em_sti_count(p) < (next - 1);
258
259 return !safe;
260}
261
262static void em_sti_register_clockevent(struct em_sti_priv *p)
263{
264 struct clock_event_device *ced = &p->ced;
265
266 ced->name = dev_name(&p->pdev->dev);
267 ced->features = CLOCK_EVT_FEAT_ONESHOT;
268 ced->rating = 200;
269 ced->cpumask = cpu_possible_mask;
270 ced->set_next_event = em_sti_clock_event_next;
271 ced->set_state_shutdown = em_sti_clock_event_shutdown;
272 ced->set_state_oneshot = em_sti_clock_event_set_oneshot;
273
274 dev_info(&p->pdev->dev, "used for clock events\n");
275
276 clockevents_config_and_register(ced, p->rate, 2, 0xffffffff);
277}
278
279static int em_sti_probe(struct platform_device *pdev)
280{
281 struct em_sti_priv *p;
282 int irq, ret;
283
284 p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
285 if (p == NULL)
286 return -ENOMEM;
287
288 p->pdev = pdev;
289 platform_set_drvdata(pdev, p);
290
291 irq = platform_get_irq(pdev, 0);
292 if (irq < 0)
293 return irq;
294
295 /* map memory, let base point to the STI instance */
296 p->base = devm_platform_ioremap_resource(pdev, 0);
297 if (IS_ERR(p->base))
298 return PTR_ERR(p->base);
299
300 ret = devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
301 IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
302 dev_name(&pdev->dev), p);
303 if (ret)
304 return ret;
305
306 /* get hold of clock */
307 p->clk = devm_clk_get(&pdev->dev, "sclk");
308 if (IS_ERR(p->clk)) {
309 dev_err(&pdev->dev, "cannot get clock\n");
310 return PTR_ERR(p->clk);
311 }
312
313 ret = clk_prepare(p->clk);
314 if (ret < 0) {
315 dev_err(&pdev->dev, "cannot prepare clock\n");
316 return ret;
317 }
318
319 ret = clk_enable(p->clk);
320 if (ret < 0) {
321 dev_err(&p->pdev->dev, "cannot enable clock\n");
322 clk_unprepare(p->clk);
323 return ret;
324 }
325 p->rate = clk_get_rate(p->clk);
326 clk_disable(p->clk);
327
328 raw_spin_lock_init(&p->lock);
329 em_sti_register_clockevent(p);
330 em_sti_register_clocksource(p);
331 return 0;
332}
333
334static const struct of_device_id em_sti_dt_ids[] = {
335 { .compatible = "renesas,em-sti", },
336 {},
337};
338MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
339
340static struct platform_driver em_sti_device_driver = {
341 .probe = em_sti_probe,
342 .driver = {
343 .name = "em_sti",
344 .of_match_table = em_sti_dt_ids,
345 .suppress_bind_attrs = true,
346 }
347};
348
349static int __init em_sti_init(void)
350{
351 return platform_driver_register(&em_sti_device_driver);
352}
353
354static void __exit em_sti_exit(void)
355{
356 platform_driver_unregister(&em_sti_device_driver);
357}
358
359subsys_initcall(em_sti_init);
360module_exit(em_sti_exit);
361
362MODULE_AUTHOR("Magnus Damm");
363MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");