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		dev_err(&pdev->dev, "failed to request low IRQ\n");
305		return ret;
306	}
307
308	/* get hold of clock */
309	p->clk = devm_clk_get(&pdev->dev, "sclk");
310	if (IS_ERR(p->clk)) {
311		dev_err(&pdev->dev, "cannot get clock\n");
312		return PTR_ERR(p->clk);
313	}
314
315	ret = clk_prepare(p->clk);
316	if (ret < 0) {
317		dev_err(&pdev->dev, "cannot prepare clock\n");
318		return ret;
319	}
320
321	ret = clk_enable(p->clk);
322	if (ret < 0) {
323		dev_err(&p->pdev->dev, "cannot enable clock\n");
324		clk_unprepare(p->clk);
325		return ret;
326	}
327	p->rate = clk_get_rate(p->clk);
328	clk_disable(p->clk);
329
330	raw_spin_lock_init(&p->lock);
331	em_sti_register_clockevent(p);
332	em_sti_register_clocksource(p);
333	return 0;
334}
335
336static const struct of_device_id em_sti_dt_ids[] = {
337	{ .compatible = "renesas,em-sti", },
338	{},
339};
340MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
341
342static struct platform_driver em_sti_device_driver = {
343	.probe		= em_sti_probe,
344	.driver		= {
345		.name	= "em_sti",
346		.of_match_table = em_sti_dt_ids,
347		.suppress_bind_attrs = true,
348	}
349};
350
351static int __init em_sti_init(void)
352{
353	return platform_driver_register(&em_sti_device_driver);
354}
355
356static void __exit em_sti_exit(void)
357{
358	platform_driver_unregister(&em_sti_device_driver);
359}
360
361subsys_initcall(em_sti_init);
362module_exit(em_sti_exit);
363
364MODULE_AUTHOR("Magnus Damm");
365MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
366