Linux 5.1.15
[linux/fpc-iii.git] / drivers / clocksource / em_sti.c
blob269db74a065815e2211194fbda9774dcf1e80041
1 /*
2 * Emma Mobile Timer Support - STI
4 * Copyright (C) 2012 Magnus Damm
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License
10 * This program is distributed in the hope that it will be useful,
11 * but WITHOUT ANY WARRANTY; without even the implied warranty of
12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
13 * GNU General Public License for more details.
15 * You should have received a copy of the GNU General Public License
16 * along with this program; if not, write to the Free Software
17 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
20 #include <linux/init.h>
21 #include <linux/platform_device.h>
22 #include <linux/spinlock.h>
23 #include <linux/interrupt.h>
24 #include <linux/ioport.h>
25 #include <linux/io.h>
26 #include <linux/clk.h>
27 #include <linux/irq.h>
28 #include <linux/err.h>
29 #include <linux/delay.h>
30 #include <linux/clocksource.h>
31 #include <linux/clockchips.h>
32 #include <linux/slab.h>
33 #include <linux/module.h>
35 enum { USER_CLOCKSOURCE, USER_CLOCKEVENT, USER_NR };
37 struct em_sti_priv {
38 void __iomem *base;
39 struct clk *clk;
40 struct platform_device *pdev;
41 unsigned int active[USER_NR];
42 unsigned long rate;
43 raw_spinlock_t lock;
44 struct clock_event_device ced;
45 struct clocksource cs;
48 #define STI_CONTROL 0x00
49 #define STI_COMPA_H 0x10
50 #define STI_COMPA_L 0x14
51 #define STI_COMPB_H 0x18
52 #define STI_COMPB_L 0x1c
53 #define STI_COUNT_H 0x20
54 #define STI_COUNT_L 0x24
55 #define STI_COUNT_RAW_H 0x28
56 #define STI_COUNT_RAW_L 0x2c
57 #define STI_SET_H 0x30
58 #define STI_SET_L 0x34
59 #define STI_INTSTATUS 0x40
60 #define STI_INTRAWSTATUS 0x44
61 #define STI_INTENSET 0x48
62 #define STI_INTENCLR 0x4c
63 #define STI_INTFFCLR 0x50
65 static inline unsigned long em_sti_read(struct em_sti_priv *p, int offs)
67 return ioread32(p->base + offs);
70 static inline void em_sti_write(struct em_sti_priv *p, int offs,
71 unsigned long value)
73 iowrite32(value, p->base + offs);
76 static int em_sti_enable(struct em_sti_priv *p)
78 int ret;
80 /* enable clock */
81 ret = clk_enable(p->clk);
82 if (ret) {
83 dev_err(&p->pdev->dev, "cannot enable clock\n");
84 return ret;
87 /* reset the counter */
88 em_sti_write(p, STI_SET_H, 0x40000000);
89 em_sti_write(p, STI_SET_L, 0x00000000);
91 /* mask and clear pending interrupts */
92 em_sti_write(p, STI_INTENCLR, 3);
93 em_sti_write(p, STI_INTFFCLR, 3);
95 /* enable updates of counter registers */
96 em_sti_write(p, STI_CONTROL, 1);
98 return 0;
101 static void em_sti_disable(struct em_sti_priv *p)
103 /* mask interrupts */
104 em_sti_write(p, STI_INTENCLR, 3);
106 /* stop clock */
107 clk_disable(p->clk);
110 static u64 em_sti_count(struct em_sti_priv *p)
112 u64 ticks;
113 unsigned long flags;
115 /* the STI hardware buffers the 48-bit count, but to
116 * break it out into two 32-bit access the registers
117 * must be accessed in a certain order.
118 * Always read STI_COUNT_H before STI_COUNT_L.
120 raw_spin_lock_irqsave(&p->lock, flags);
121 ticks = (u64)(em_sti_read(p, STI_COUNT_H) & 0xffff) << 32;
122 ticks |= em_sti_read(p, STI_COUNT_L);
123 raw_spin_unlock_irqrestore(&p->lock, flags);
125 return ticks;
128 static u64 em_sti_set_next(struct em_sti_priv *p, u64 next)
130 unsigned long flags;
132 raw_spin_lock_irqsave(&p->lock, flags);
134 /* mask compare A interrupt */
135 em_sti_write(p, STI_INTENCLR, 1);
137 /* update compare A value */
138 em_sti_write(p, STI_COMPA_H, next >> 32);
139 em_sti_write(p, STI_COMPA_L, next & 0xffffffff);
141 /* clear compare A interrupt source */
142 em_sti_write(p, STI_INTFFCLR, 1);
144 /* unmask compare A interrupt */
145 em_sti_write(p, STI_INTENSET, 1);
147 raw_spin_unlock_irqrestore(&p->lock, flags);
149 return next;
152 static irqreturn_t em_sti_interrupt(int irq, void *dev_id)
154 struct em_sti_priv *p = dev_id;
156 p->ced.event_handler(&p->ced);
157 return IRQ_HANDLED;
160 static int em_sti_start(struct em_sti_priv *p, unsigned int user)
162 unsigned long flags;
163 int used_before;
164 int ret = 0;
166 raw_spin_lock_irqsave(&p->lock, flags);
167 used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
168 if (!used_before)
169 ret = em_sti_enable(p);
171 if (!ret)
172 p->active[user] = 1;
173 raw_spin_unlock_irqrestore(&p->lock, flags);
175 return ret;
178 static void em_sti_stop(struct em_sti_priv *p, unsigned int user)
180 unsigned long flags;
181 int used_before, used_after;
183 raw_spin_lock_irqsave(&p->lock, flags);
184 used_before = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
185 p->active[user] = 0;
186 used_after = p->active[USER_CLOCKSOURCE] | p->active[USER_CLOCKEVENT];
188 if (used_before && !used_after)
189 em_sti_disable(p);
190 raw_spin_unlock_irqrestore(&p->lock, flags);
193 static struct em_sti_priv *cs_to_em_sti(struct clocksource *cs)
195 return container_of(cs, struct em_sti_priv, cs);
198 static u64 em_sti_clocksource_read(struct clocksource *cs)
200 return em_sti_count(cs_to_em_sti(cs));
203 static int em_sti_clocksource_enable(struct clocksource *cs)
205 struct em_sti_priv *p = cs_to_em_sti(cs);
207 return em_sti_start(p, USER_CLOCKSOURCE);
210 static void em_sti_clocksource_disable(struct clocksource *cs)
212 em_sti_stop(cs_to_em_sti(cs), USER_CLOCKSOURCE);
215 static void em_sti_clocksource_resume(struct clocksource *cs)
217 em_sti_clocksource_enable(cs);
220 static int em_sti_register_clocksource(struct em_sti_priv *p)
222 struct clocksource *cs = &p->cs;
224 cs->name = dev_name(&p->pdev->dev);
225 cs->rating = 200;
226 cs->read = em_sti_clocksource_read;
227 cs->enable = em_sti_clocksource_enable;
228 cs->disable = em_sti_clocksource_disable;
229 cs->suspend = em_sti_clocksource_disable;
230 cs->resume = em_sti_clocksource_resume;
231 cs->mask = CLOCKSOURCE_MASK(48);
232 cs->flags = CLOCK_SOURCE_IS_CONTINUOUS;
234 dev_info(&p->pdev->dev, "used as clock source\n");
236 clocksource_register_hz(cs, p->rate);
237 return 0;
240 static struct em_sti_priv *ced_to_em_sti(struct clock_event_device *ced)
242 return container_of(ced, struct em_sti_priv, ced);
245 static int em_sti_clock_event_shutdown(struct clock_event_device *ced)
247 struct em_sti_priv *p = ced_to_em_sti(ced);
248 em_sti_stop(p, USER_CLOCKEVENT);
249 return 0;
252 static int em_sti_clock_event_set_oneshot(struct clock_event_device *ced)
254 struct em_sti_priv *p = ced_to_em_sti(ced);
256 dev_info(&p->pdev->dev, "used for oneshot clock events\n");
257 em_sti_start(p, USER_CLOCKEVENT);
258 return 0;
261 static int em_sti_clock_event_next(unsigned long delta,
262 struct clock_event_device *ced)
264 struct em_sti_priv *p = ced_to_em_sti(ced);
265 u64 next;
266 int safe;
268 next = em_sti_set_next(p, em_sti_count(p) + delta);
269 safe = em_sti_count(p) < (next - 1);
271 return !safe;
274 static void em_sti_register_clockevent(struct em_sti_priv *p)
276 struct clock_event_device *ced = &p->ced;
278 ced->name = dev_name(&p->pdev->dev);
279 ced->features = CLOCK_EVT_FEAT_ONESHOT;
280 ced->rating = 200;
281 ced->cpumask = cpu_possible_mask;
282 ced->set_next_event = em_sti_clock_event_next;
283 ced->set_state_shutdown = em_sti_clock_event_shutdown;
284 ced->set_state_oneshot = em_sti_clock_event_set_oneshot;
286 dev_info(&p->pdev->dev, "used for clock events\n");
288 clockevents_config_and_register(ced, p->rate, 2, 0xffffffff);
291 static int em_sti_probe(struct platform_device *pdev)
293 struct em_sti_priv *p;
294 struct resource *res;
295 int irq;
296 int ret;
298 p = devm_kzalloc(&pdev->dev, sizeof(*p), GFP_KERNEL);
299 if (p == NULL)
300 return -ENOMEM;
302 p->pdev = pdev;
303 platform_set_drvdata(pdev, p);
305 irq = platform_get_irq(pdev, 0);
306 if (irq < 0) {
307 dev_err(&pdev->dev, "failed to get irq\n");
308 return irq;
311 /* map memory, let base point to the STI instance */
312 res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
313 p->base = devm_ioremap_resource(&pdev->dev, res);
314 if (IS_ERR(p->base))
315 return PTR_ERR(p->base);
317 ret = devm_request_irq(&pdev->dev, irq, em_sti_interrupt,
318 IRQF_TIMER | IRQF_IRQPOLL | IRQF_NOBALANCING,
319 dev_name(&pdev->dev), p);
320 if (ret) {
321 dev_err(&pdev->dev, "failed to request low IRQ\n");
322 return ret;
325 /* get hold of clock */
326 p->clk = devm_clk_get(&pdev->dev, "sclk");
327 if (IS_ERR(p->clk)) {
328 dev_err(&pdev->dev, "cannot get clock\n");
329 return PTR_ERR(p->clk);
332 ret = clk_prepare(p->clk);
333 if (ret < 0) {
334 dev_err(&pdev->dev, "cannot prepare clock\n");
335 return ret;
338 ret = clk_enable(p->clk);
339 if (ret < 0) {
340 dev_err(&p->pdev->dev, "cannot enable clock\n");
341 clk_unprepare(p->clk);
342 return ret;
344 p->rate = clk_get_rate(p->clk);
345 clk_disable(p->clk);
347 raw_spin_lock_init(&p->lock);
348 em_sti_register_clockevent(p);
349 em_sti_register_clocksource(p);
350 return 0;
353 static int em_sti_remove(struct platform_device *pdev)
355 return -EBUSY; /* cannot unregister clockevent and clocksource */
358 static const struct of_device_id em_sti_dt_ids[] = {
359 { .compatible = "renesas,em-sti", },
362 MODULE_DEVICE_TABLE(of, em_sti_dt_ids);
364 static struct platform_driver em_sti_device_driver = {
365 .probe = em_sti_probe,
366 .remove = em_sti_remove,
367 .driver = {
368 .name = "em_sti",
369 .of_match_table = em_sti_dt_ids,
373 static int __init em_sti_init(void)
375 return platform_driver_register(&em_sti_device_driver);
378 static void __exit em_sti_exit(void)
380 platform_driver_unregister(&em_sti_device_driver);
383 subsys_initcall(em_sti_init);
384 module_exit(em_sti_exit);
386 MODULE_AUTHOR("Magnus Damm");
387 MODULE_DESCRIPTION("Renesas Emma Mobile STI Timer Driver");
388 MODULE_LICENSE("GPL v2");