bcm2835_systimer.c revision 266152 
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/10/sys/arm/broadcom/bcm2835/bcm2835_systimer.c 266152 2014-05-15 16:11:06Z ian $");
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
45#include <dev/fdt/fdt_common.h>
46#include <dev/ofw/openfirm.h>
47#include <dev/ofw/ofw_bus.h>
48#include <dev/ofw/ofw_bus_subr.h>
49
50#include <machine/bus.h>
51#include <machine/fdt.h>
52
53#define	BCM2835_NUM_TIMERS	4
54
55#define	DEFAULT_TIMER		3
56#define	DEFAULT_FREQUENCY	1000000
57#define	MIN_PERIOD		5LLU
58
59#define	SYSTIMER_CS	0x00
60#define	SYSTIMER_CLO	0x04
61#define	SYSTIMER_CHI	0x08
62#define	SYSTIMER_C0	0x0C
63#define	SYSTIMER_C1	0x10
64#define	SYSTIMER_C2	0x14
65#define	SYSTIMER_C3	0x18
66
67struct systimer {
68	int			index;
69	bool			enabled;
70	struct eventtimer	et;
71};
72
73struct bcm_systimer_softc {
74	struct resource*	mem_res;
75	struct resource*	irq_res[BCM2835_NUM_TIMERS];
76	void*			intr_hl[BCM2835_NUM_TIMERS];
77	uint32_t		sysclk_freq;
78	bus_space_tag_t		bst;
79	bus_space_handle_t	bsh;
80	struct systimer		st[BCM2835_NUM_TIMERS];
81};
82
83static struct resource_spec bcm_systimer_irq_spec[] = {
84	{ SYS_RES_IRQ,      0,  RF_ACTIVE },
85	{ SYS_RES_IRQ,      1,  RF_ACTIVE },
86	{ SYS_RES_IRQ,      2,  RF_ACTIVE },
87	{ SYS_RES_IRQ,      3,  RF_ACTIVE },
88	{ -1,               0,  0 }
89};
90
91static struct bcm_systimer_softc *bcm_systimer_sc = NULL;
92
93/* Read/Write macros for Timer used as timecounter */
94#define bcm_systimer_tc_read_4(reg)		\
95	bus_space_read_4(bcm_systimer_sc->bst, \
96		bcm_systimer_sc->bsh, reg)
97
98#define bcm_systimer_tc_write_4(reg, val)	\
99	bus_space_write_4(bcm_systimer_sc->bst, \
100		bcm_systimer_sc->bsh, reg, val)
101
102static unsigned bcm_systimer_tc_get_timecount(struct timecounter *);
103
104static struct timecounter bcm_systimer_tc = {
105	.tc_name           = "BCM2835 Timecounter",
106	.tc_get_timecount  = bcm_systimer_tc_get_timecount,
107	.tc_poll_pps       = NULL,
108	.tc_counter_mask   = ~0u,
109	.tc_frequency      = 0,
110	.tc_quality        = 1000,
111};
112
113static unsigned
114bcm_systimer_tc_get_timecount(struct timecounter *tc)
115{
116	return bcm_systimer_tc_read_4(SYSTIMER_CLO);
117}
118
119static int
120bcm_systimer_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
121{
122	struct systimer *st = et->et_priv;
123	uint32_t clo, clo1;
124	uint32_t count;
125	register_t s;
126
127	if (first != 0) {
128
129		count = ((uint32_t)et->et_frequency * first) >> 32;
130
131		s = intr_disable();
132		clo = bcm_systimer_tc_read_4(SYSTIMER_CLO);
133restart:
134		clo += count;
135		/*
136		 * Clear pending interrupts
137		 */
138		bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index));
139		bcm_systimer_tc_write_4(SYSTIMER_C0 + st->index*4, clo);
140		clo1 = bcm_systimer_tc_read_4(SYSTIMER_CLO);
141		if ((int32_t)(clo1 - clo) >= 0) {
142			count *= 2;
143			clo = clo1;
144			goto restart;
145		}
146		st->enabled = 1;
147		intr_restore(s);
148
149		return (0);
150	}
151
152	return (EINVAL);
153}
154
155static int
156bcm_systimer_stop(struct eventtimer *et)
157{
158	struct systimer *st = et->et_priv;
159	st->enabled = 0;
160
161	return (0);
162}
163
164static int
165bcm_systimer_intr(void *arg)
166{
167	struct systimer *st = (struct systimer *)arg;
168	uint32_t cs;
169
170 	cs = bcm_systimer_tc_read_4(SYSTIMER_CS);
171	if ((cs & (1 << st->index)) == 0)
172		return (FILTER_STRAY);
173
174	/* ACK interrupt */
175	bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index));
176	if (st->enabled) {
177		if (st->et.et_active) {
178			st->et.et_event_cb(&st->et, st->et.et_arg);
179		}
180	}
181
182	return (FILTER_HANDLED);
183}
184
185static int
186bcm_systimer_probe(device_t dev)
187{
188
189	if (!ofw_bus_status_okay(dev))
190		return (ENXIO);
191
192	if (ofw_bus_is_compatible(dev, "broadcom,bcm2835-system-timer")) {
193		device_set_desc(dev, "BCM2835 System Timer");
194		return (BUS_PROBE_DEFAULT);
195	}
196
197	return (ENXIO);
198}
199
200static int
201bcm_systimer_attach(device_t dev)
202{
203	struct bcm_systimer_softc *sc = device_get_softc(dev);
204	int err;
205	int rid = 0;
206
207	if (bcm_systimer_sc != NULL)
208		return (EINVAL);
209
210	sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE);
211	if (sc->mem_res == NULL) {
212		device_printf(dev, "could not allocate memory resource\n");
213		return (ENXIO);
214	}
215
216	sc->bst = rman_get_bustag(sc->mem_res);
217	sc->bsh = rman_get_bushandle(sc->mem_res);
218
219	/* Request the IRQ resources */
220	err = bus_alloc_resources(dev, bcm_systimer_irq_spec,
221		sc->irq_res);
222	if (err) {
223		device_printf(dev, "Error: could not allocate irq resources\n");
224		return (ENXIO);
225	}
226
227	/* TODO: get frequency from FDT */
228	sc->sysclk_freq = DEFAULT_FREQUENCY;
229
230	/* Setup and enable the timer */
231	if (bus_setup_intr(dev, sc->irq_res[DEFAULT_TIMER], INTR_TYPE_CLK,
232			bcm_systimer_intr, NULL, &sc->st[DEFAULT_TIMER],
233			&sc->intr_hl[DEFAULT_TIMER]) != 0) {
234		bus_release_resources(dev, bcm_systimer_irq_spec,
235			sc->irq_res);
236		device_printf(dev, "Unable to setup the clock irq handler.\n");
237		return (ENXIO);
238	}
239
240	sc->st[DEFAULT_TIMER].index = DEFAULT_TIMER;
241	sc->st[DEFAULT_TIMER].enabled = 0;
242	sc->st[DEFAULT_TIMER].et.et_name = malloc(64, M_DEVBUF, M_NOWAIT | M_ZERO);
243	sprintf(sc->st[DEFAULT_TIMER].et.et_name, "BCM2835 Event Timer %d", DEFAULT_TIMER);
244	sc->st[DEFAULT_TIMER].et.et_flags = ET_FLAGS_ONESHOT;
245	sc->st[DEFAULT_TIMER].et.et_quality = 1000;
246	sc->st[DEFAULT_TIMER].et.et_frequency = sc->sysclk_freq;
247	sc->st[DEFAULT_TIMER].et.et_min_period =
248	    (MIN_PERIOD << 32) / sc->st[DEFAULT_TIMER].et.et_frequency + 1;
249	sc->st[DEFAULT_TIMER].et.et_max_period =
250	    (0x7ffffffeLLU << 32) / sc->st[DEFAULT_TIMER].et.et_frequency;
251	sc->st[DEFAULT_TIMER].et.et_start = bcm_systimer_start;
252	sc->st[DEFAULT_TIMER].et.et_stop = bcm_systimer_stop;
253	sc->st[DEFAULT_TIMER].et.et_priv = &sc->st[DEFAULT_TIMER];
254	et_register(&sc->st[DEFAULT_TIMER].et);
255
256	bcm_systimer_sc = sc;
257
258	bcm_systimer_tc.tc_frequency = DEFAULT_FREQUENCY;
259	tc_init(&bcm_systimer_tc);
260
261	return (0);
262}
263
264static device_method_t bcm_systimer_methods[] = {
265	DEVMETHOD(device_probe,		bcm_systimer_probe),
266	DEVMETHOD(device_attach,	bcm_systimer_attach),
267	{ 0, 0 }
268};
269
270static driver_t bcm_systimer_driver = {
271	"systimer",
272	bcm_systimer_methods,
273	sizeof(struct bcm_systimer_softc),
274};
275
276static devclass_t bcm_systimer_devclass;
277
278DRIVER_MODULE(bcm_systimer, simplebus, bcm_systimer_driver, bcm_systimer_devclass, 0, 0);
279
280void
281cpu_initclocks(void)
282{
283	cpu_initclocks_bsp();
284}
285
286void
287DELAY(int usec)
288{
289	int32_t counts;
290	uint32_t first, last;
291
292	if (bcm_systimer_sc == NULL) {
293		for (; usec > 0; usec--)
294			for (counts = 200; counts > 0; counts--)
295				/* Prevent gcc from optimizing  out the loop */
296				cpufunc_nullop();
297		return;
298	}
299
300	/* Get the number of times to count */
301	counts = usec * (bcm_systimer_tc.tc_frequency / 1000000) + 1;
302
303	first = bcm_systimer_tc_read_4(SYSTIMER_CLO);
304
305	while (counts > 0) {
306		last = bcm_systimer_tc_read_4(SYSTIMER_CLO);
307		if (last == first)
308			continue;
309		if (last>first) {
310			counts -= (int32_t)(last - first);
311		} else {
312			counts -= (int32_t)((0xFFFFFFFF - first) + last);
313		}
314		first = last;
315	}
316}
317