bcm2835_systimer.c revision 331894 
1/*
2 * Copyright (c) 2012 Oleksandr Tymoshenko <gonzo@freebsd.org>
3 * Copyright (c) 2012 Damjan Marion <dmarion@freebsd.org>
4 * All rights reserved.
5 *
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
8 * are met:
9 * 1. Redistributions of source code must retain the above copyright
10 *    notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 *    notice, this list of conditions and the following disclaimer in the
13 *    documentation and/or other materials provided with the distribution.
14 *
15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
18 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
25 * SUCH DAMAGE.
26 */
27
28#include <sys/cdefs.h>
29__FBSDID("$FreeBSD: stable/11/sys/arm/broadcom/bcm2835/bcm2835_systimer.c 331894 2018-04-02 23:30:21Z gonzo $");
30
31#include <sys/param.h>
32#include <sys/systm.h>
33#include <sys/bus.h>
34#include <sys/kernel.h>
35#include <sys/module.h>
36#include <sys/malloc.h>
37#include <sys/rman.h>
38#include <sys/timeet.h>
39#include <sys/timetc.h>
40#include <sys/watchdog.h>
41#include <machine/bus.h>
42#include <machine/cpu.h>
43#include <machine/intr.h>
44#include <machine/machdep.h>
45
46#include <dev/fdt/fdt_common.h>
47#include <dev/ofw/openfirm.h>
48#include <dev/ofw/ofw_bus.h>
49#include <dev/ofw/ofw_bus_subr.h>
50
51#include <machine/bus.h>
52
53#define	BCM2835_NUM_TIMERS	4
54
55#define	DEFAULT_TIMER		3
56#define	DEFAULT_TIMER_NAME	"BCM2835-3"
57#define	DEFAULT_FREQUENCY	1000000
58#define	MIN_PERIOD		5LLU
59
60#define	SYSTIMER_CS	0x00
61#define	SYSTIMER_CLO	0x04
62#define	SYSTIMER_CHI	0x08
63#define	SYSTIMER_C0	0x0C
64#define	SYSTIMER_C1	0x10
65#define	SYSTIMER_C2	0x14
66#define	SYSTIMER_C3	0x18
67
68struct systimer {
69	int			index;
70	bool			enabled;
71	struct eventtimer	et;
72};
73
74struct bcm_systimer_softc {
75	struct resource*	mem_res;
76	struct resource*	irq_res[BCM2835_NUM_TIMERS];
77	void*			intr_hl[BCM2835_NUM_TIMERS];
78	uint32_t		sysclk_freq;
79	bus_space_tag_t		bst;
80	bus_space_handle_t	bsh;
81	struct systimer		st[BCM2835_NUM_TIMERS];
82};
83
84static struct resource_spec bcm_systimer_irq_spec[] = {
85	{ SYS_RES_IRQ,      0,  RF_ACTIVE },
86	{ SYS_RES_IRQ,      1,  RF_ACTIVE },
87	{ SYS_RES_IRQ,      2,  RF_ACTIVE },
88	{ SYS_RES_IRQ,      3,  RF_ACTIVE },
89	{ -1,               0,  0 }
90};
91
92static struct bcm_systimer_softc *bcm_systimer_sc = NULL;
93
94/* Read/Write macros for Timer used as timecounter */
95#define bcm_systimer_tc_read_4(reg)		\
96	bus_space_read_4(bcm_systimer_sc->bst, \
97		bcm_systimer_sc->bsh, reg)
98
99#define bcm_systimer_tc_write_4(reg, val)	\
100	bus_space_write_4(bcm_systimer_sc->bst, \
101		bcm_systimer_sc->bsh, reg, val)
102
103static unsigned bcm_systimer_tc_get_timecount(struct timecounter *);
104
105static delay_func bcm_systimer_delay;
106
107static struct timecounter bcm_systimer_tc = {
108	.tc_name           = DEFAULT_TIMER_NAME,
109	.tc_get_timecount  = bcm_systimer_tc_get_timecount,
110	.tc_poll_pps       = NULL,
111	.tc_counter_mask   = ~0u,
112	.tc_frequency      = 0,
113	.tc_quality        = 1000,
114};
115
116static unsigned
117bcm_systimer_tc_get_timecount(struct timecounter *tc)
118{
119	if (bcm_systimer_sc == NULL)
120		return (0);
121
122	return bcm_systimer_tc_read_4(SYSTIMER_CLO);
123}
124
125static int
126bcm_systimer_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
127{
128	struct systimer *st = et->et_priv;
129	uint32_t clo, clo1;
130	uint32_t count;
131	register_t s;
132
133	if (first != 0) {
134
135		count = ((uint32_t)et->et_frequency * first) >> 32;
136
137		s = intr_disable();
138		clo = bcm_systimer_tc_read_4(SYSTIMER_CLO);
139restart:
140		clo += count;
141		/*
142		 * Clear pending interrupts
143		 */
144		bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index));
145		bcm_systimer_tc_write_4(SYSTIMER_C0 + st->index*4, clo);
146		clo1 = bcm_systimer_tc_read_4(SYSTIMER_CLO);
147		if ((int32_t)(clo1 - clo) >= 0) {
148			count *= 2;
149			clo = clo1;
150			goto restart;
151		}
152		st->enabled = 1;
153		intr_restore(s);
154
155		return (0);
156	}
157
158	return (EINVAL);
159}
160
161static int
162bcm_systimer_stop(struct eventtimer *et)
163{
164	struct systimer *st = et->et_priv;
165	st->enabled = 0;
166
167	return (0);
168}
169
170static int
171bcm_systimer_intr(void *arg)
172{
173	struct systimer *st = (struct systimer *)arg;
174	uint32_t cs;
175
176	cs = bcm_systimer_tc_read_4(SYSTIMER_CS);
177	if ((cs & (1 << st->index)) == 0)
178		return (FILTER_STRAY);
179
180	/* ACK interrupt */
181	bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index));
182	if (st->enabled) {
183		if (st->et.et_active) {
184			st->et.et_event_cb(&st->et, st->et.et_arg);
185		}
186	}
187
188	return (FILTER_HANDLED);
189}
190
191static int
192bcm_systimer_probe(device_t dev)
193{
194
195	if (!ofw_bus_status_okay(dev))
196		return (ENXIO);
197
198	if (ofw_bus_is_compatible(dev, "broadcom,bcm2835-system-timer")) {
199		device_set_desc(dev, "BCM2835 System Timer");
200		return (BUS_PROBE_DEFAULT);
201	}
202
203	return (ENXIO);
204}
205
206static int
207bcm_systimer_attach(device_t dev)
208{
209	struct bcm_systimer_softc *sc = device_get_softc(dev);
210	int err;
211	int rid = 0;
212
213	if (bcm_systimer_sc != NULL)
214		return (EINVAL);
215
216	sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE);
217	if (sc->mem_res == NULL) {
218		device_printf(dev, "could not allocate memory resource\n");
219		return (ENXIO);
220	}
221
222	sc->bst = rman_get_bustag(sc->mem_res);
223	sc->bsh = rman_get_bushandle(sc->mem_res);
224
225	/* Request the IRQ resources */
226	err = bus_alloc_resources(dev, bcm_systimer_irq_spec,
227		sc->irq_res);
228	if (err) {
229		device_printf(dev, "Error: could not allocate irq resources\n");
230		return (ENXIO);
231	}
232
233	/* TODO: get frequency from FDT */
234	sc->sysclk_freq = DEFAULT_FREQUENCY;
235
236	/* Setup and enable the timer */
237	if (bus_setup_intr(dev, sc->irq_res[DEFAULT_TIMER], INTR_TYPE_CLK,
238			bcm_systimer_intr, NULL, &sc->st[DEFAULT_TIMER],
239			&sc->intr_hl[DEFAULT_TIMER]) != 0) {
240		bus_release_resources(dev, bcm_systimer_irq_spec,
241			sc->irq_res);
242		device_printf(dev, "Unable to setup the clock irq handler.\n");
243		return (ENXIO);
244	}
245
246	sc->st[DEFAULT_TIMER].index = DEFAULT_TIMER;
247	sc->st[DEFAULT_TIMER].enabled = 0;
248	sc->st[DEFAULT_TIMER].et.et_name = DEFAULT_TIMER_NAME;
249	sc->st[DEFAULT_TIMER].et.et_flags = ET_FLAGS_ONESHOT;
250	sc->st[DEFAULT_TIMER].et.et_quality = 1000;
251	sc->st[DEFAULT_TIMER].et.et_frequency = sc->sysclk_freq;
252	sc->st[DEFAULT_TIMER].et.et_min_period =
253	    (MIN_PERIOD << 32) / sc->st[DEFAULT_TIMER].et.et_frequency + 1;
254	sc->st[DEFAULT_TIMER].et.et_max_period =
255	    (0x7ffffffeLLU << 32) / sc->st[DEFAULT_TIMER].et.et_frequency;
256	sc->st[DEFAULT_TIMER].et.et_start = bcm_systimer_start;
257	sc->st[DEFAULT_TIMER].et.et_stop = bcm_systimer_stop;
258	sc->st[DEFAULT_TIMER].et.et_priv = &sc->st[DEFAULT_TIMER];
259	et_register(&sc->st[DEFAULT_TIMER].et);
260
261	bcm_systimer_sc = sc;
262
263	if (device_get_unit(dev) == 0)
264		arm_set_delay(bcm_systimer_delay, sc);
265
266	bcm_systimer_tc.tc_frequency = DEFAULT_FREQUENCY;
267	tc_init(&bcm_systimer_tc);
268
269	return (0);
270}
271
272static device_method_t bcm_systimer_methods[] = {
273	DEVMETHOD(device_probe,		bcm_systimer_probe),
274	DEVMETHOD(device_attach,	bcm_systimer_attach),
275	{ 0, 0 }
276};
277
278static driver_t bcm_systimer_driver = {
279	"systimer",
280	bcm_systimer_methods,
281	sizeof(struct bcm_systimer_softc),
282};
283
284static devclass_t bcm_systimer_devclass;
285
286DRIVER_MODULE(bcm_systimer, simplebus, bcm_systimer_driver, bcm_systimer_devclass, 0, 0);
287
288static void
289bcm_systimer_delay(int usec, void *arg)
290{
291	struct bcm_systimer_softc *sc;
292	int32_t counts;
293	uint32_t first, last;
294
295	sc = (struct bcm_systimer_softc *) arg;
296
297	/* Get the number of times to count */
298	counts = usec * (bcm_systimer_tc.tc_frequency / 1000000) + 1;
299
300	first = bcm_systimer_tc_read_4(SYSTIMER_CLO);
301
302	while (counts > 0) {
303		last = bcm_systimer_tc_read_4(SYSTIMER_CLO);
304		if (last == first)
305			continue;
306		if (last>first) {
307			counts -= (int32_t)(last - first);
308		} else {
309			counts -= (int32_t)((0xFFFFFFFF - first) + last);
310		}
311		first = last;
312	}
313}
314