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 | |
23 | enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR }; |
24 | |
25 | struct 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 | |
53 | static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs) |
54 | { |
55 | return ioread32(p->base + offs); |
56 | } |
57 | |
58 | static 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 | |
64 | static int em_sti_enable(struct em_sti_priv *p) |
65 | { |
66 | int ret; |
67 | |
68 | /* enable clock */ |
69 | ret = clk_enable(clk: 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, value: 0x40000000); |
77 | em_sti_write(p, STI_SET_L, value: 0x00000000); |
78 | |
79 | /* mask and clear pending interrupts */ |
80 | em_sti_write(p, STI_INTENCLR, value: 3); |
81 | em_sti_write(p, STI_INTFFCLR, value: 3); |
82 | |
83 | /* enable updates of counter registers */ |
84 | em_sti_write(p, STI_CONTROL, value: 1); |
85 | |
86 | return 0; |
87 | } |
88 | |
89 | static void em_sti_disable(struct em_sti_priv *p) |
90 | { |
91 | /* mask interrupts */ |
92 | em_sti_write(p, STI_INTENCLR, value: 3); |
93 | |
94 | /* stop clock */ |
95 | clk_disable(clk: p->clk); |
96 | } |
97 | |
98 | static 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 | |
116 | static 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, value: 1); |
124 | |
125 | /* update compare A value */ |
126 | em_sti_write(p, STI_COMPA_H, value: next >> 32); |
127 | em_sti_write(p, STI_COMPA_L, value: next & 0xffffffff); |
128 | |
129 | /* clear compare A interrupt source */ |
130 | em_sti_write(p, STI_INTFFCLR, value: 1); |
131 | |
132 | /* unmask compare A interrupt */ |
133 | em_sti_write(p, STI_INTENSET, value: 1); |
134 | |
135 | raw_spin_unlock_irqrestore(&p->lock, flags); |
136 | |
137 | return next; |
138 | } |
139 | |
140 | static 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 | |
148 | static 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 | |
166 | static 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 | |
181 | static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs) |
182 | { |
183 | return container_of(cs, struct em_sti_priv, cs); |
184 | } |
185 | |
186 | static u64 em_sti_clocksource_read(struct clocksource *cs) |
187 | { |
188 | return em_sti_count(p: cs_to_em_sti(cs)); |
189 | } |
190 | |
191 | static 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: USER_CLOCKSOURCE); |
196 | } |
197 | |
198 | static void em_sti_clocksource_disable(struct clocksource *cs) |
199 | { |
200 | em_sti_stop(p: cs_to_em_sti(cs), user: USER_CLOCKSOURCE); |
201 | } |
202 | |
203 | static void em_sti_clocksource_resume(struct clocksource *cs) |
204 | { |
205 | em_sti_clocksource_enable(cs); |
206 | } |
207 | |
208 | static int em_sti_register_clocksource(struct em_sti_priv *p) |
209 | { |
210 | struct clocksource *cs = &p->cs; |
211 | |
212 | cs->name = dev_name(dev: &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, hz: p->rate); |
225 | return 0; |
226 | } |
227 | |
228 | static 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 | |
233 | static 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: USER_CLOCKEVENT); |
237 | return 0; |
238 | } |
239 | |
240 | static 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: USER_CLOCKEVENT); |
246 | return 0; |
247 | } |
248 | |
249 | static 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, next: em_sti_count(p) + delta); |
257 | safe = em_sti_count(p) < (next - 1); |
258 | |
259 | return !safe; |
260 | } |
261 | |
262 | static 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(dev: &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(dev: ced, freq: p->rate, min_delta: 2, max_delta: 0xffffffff); |
277 | } |
278 | |
279 | static int em_sti_probe(struct platform_device *pdev) |
280 | { |
281 | struct em_sti_priv *p; |
282 | int irq, ret; |
283 | |
284 | p = devm_kzalloc(dev: &pdev->dev, size: sizeof(*p), GFP_KERNEL); |
285 | if (p == NULL) |
286 | return -ENOMEM; |
287 | |
288 | p->pdev = pdev; |
289 | platform_set_drvdata(pdev, data: 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, index: 0); |
297 | if (IS_ERR(ptr: p->base)) |
298 | return PTR_ERR(ptr: p->base); |
299 | |
300 | ret = devm_request_irq(dev: &pdev->dev, irq, handler: em_sti_interrupt, |
301 | IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING, |
302 | devname: dev_name(dev: &pdev->dev), dev_id: 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(dev: &pdev->dev, id: "sclk" ); |
310 | if (IS_ERR(ptr: p->clk)) { |
311 | dev_err(&pdev->dev, "cannot get clock\n" ); |
312 | return PTR_ERR(ptr: p->clk); |
313 | } |
314 | |
315 | ret = clk_prepare(clk: p->clk); |
316 | if (ret < 0) { |
317 | dev_err(&pdev->dev, "cannot prepare clock\n" ); |
318 | return ret; |
319 | } |
320 | |
321 | ret = clk_enable(clk: p->clk); |
322 | if (ret < 0) { |
323 | dev_err(&p->pdev->dev, "cannot enable clock\n" ); |
324 | clk_unprepare(clk: p->clk); |
325 | return ret; |
326 | } |
327 | p->rate = clk_get_rate(clk: p->clk); |
328 | clk_disable(clk: 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 | |
336 | static const struct of_device_id em_sti_dt_ids[] = { |
337 | { .compatible = "renesas,em-sti" , }, |
338 | {}, |
339 | }; |
340 | MODULE_DEVICE_TABLE(of, em_sti_dt_ids); |
341 | |
342 | static 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 | |
351 | static int __init em_sti_init(void) |
352 | { |
353 | return platform_driver_register(&em_sti_device_driver); |
354 | } |
355 | |
356 | static void __exit em_sti_exit(void) |
357 | { |
358 | platform_driver_unregister(&em_sti_device_driver); |
359 | } |
360 | |
361 | subsys_initcall(em_sti_init); |
362 | module_exit(em_sti_exit); |
363 | |
364 | MODULE_AUTHOR("Magnus Damm" ); |
365 | MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver" ); |
366 | |