bcm2835_systimer.c revision 330897 
1/*
2 * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
3 *
4 * Copyright (c) 2012 Oleksandr Tymoshenko <gonzo@freebsd.org>
5 * Copyright (c) 2012 Damjan Marion <dmarion@freebsd.org>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29
30#include <sys/cdefs.h>
31__FBSDID("$FreeBSD: stable/11/sys/arm/broadcom/bcm2835/bcm2835_systimer.c 330897 2018-03-14 03:19:51Z eadler $");
32
33#include <sys/param.h>
34#include <sys/systm.h>
35#include <sys/bus.h>
36#include <sys/kernel.h>
37#include <sys/module.h>
38#include <sys/malloc.h>
39#include <sys/rman.h>
40#include <sys/timeet.h>
41#include <sys/timetc.h>
42#include <sys/watchdog.h>
43#include <machine/bus.h>
44#include <machine/cpu.h>
45#include <machine/intr.h>
46
47#include <dev/fdt/fdt_common.h>
48#include <dev/ofw/openfirm.h>
49#include <dev/ofw/ofw_bus.h>
50#include <dev/ofw/ofw_bus_subr.h>
51
52#include <machine/bus.h>
53
54#define	BCM2835_NUM_TIMERS	4
55
56#define	DEFAULT_TIMER		3
57#define	DEFAULT_TIMER_NAME	"BCM2835-3"
58#define	DEFAULT_FREQUENCY	1000000
59#define	MIN_PERIOD		5LLU
60
61#define	SYSTIMER_CS	0x00
62#define	SYSTIMER_CLO	0x04
63#define	SYSTIMER_CHI	0x08
64#define	SYSTIMER_C0	0x0C
65#define	SYSTIMER_C1	0x10
66#define	SYSTIMER_C2	0x14
67#define	SYSTIMER_C3	0x18
68
69struct systimer {
70	int			index;
71	bool			enabled;
72	struct eventtimer	et;
73};
74
75struct bcm_systimer_softc {
76	struct resource*	mem_res;
77	struct resource*	irq_res[BCM2835_NUM_TIMERS];
78	void*			intr_hl[BCM2835_NUM_TIMERS];
79	uint32_t		sysclk_freq;
80	bus_space_tag_t		bst;
81	bus_space_handle_t	bsh;
82	struct systimer		st[BCM2835_NUM_TIMERS];
83};
84
85static struct resource_spec bcm_systimer_irq_spec[] = {
86	{ SYS_RES_IRQ,      0,  RF_ACTIVE },
87	{ SYS_RES_IRQ,      1,  RF_ACTIVE },
88	{ SYS_RES_IRQ,      2,  RF_ACTIVE },
89	{ SYS_RES_IRQ,      3,  RF_ACTIVE },
90	{ -1,               0,  0 }
91};
92
93static struct bcm_systimer_softc *bcm_systimer_sc = NULL;
94
95/* Read/Write macros for Timer used as timecounter */
96#define bcm_systimer_tc_read_4(reg)		\
97	bus_space_read_4(bcm_systimer_sc->bst, \
98		bcm_systimer_sc->bsh, reg)
99
100#define bcm_systimer_tc_write_4(reg, val)	\
101	bus_space_write_4(bcm_systimer_sc->bst, \
102		bcm_systimer_sc->bsh, reg, val)
103
104static unsigned bcm_systimer_tc_get_timecount(struct timecounter *);
105
106static struct timecounter bcm_systimer_tc = {
107	.tc_name           = DEFAULT_TIMER_NAME,
108	.tc_get_timecount  = bcm_systimer_tc_get_timecount,
109	.tc_poll_pps       = NULL,
110	.tc_counter_mask   = ~0u,
111	.tc_frequency      = 0,
112	.tc_quality        = 1000,
113};
114
115static unsigned
116bcm_systimer_tc_get_timecount(struct timecounter *tc)
117{
118	return bcm_systimer_tc_read_4(SYSTIMER_CLO);
119}
120
121static int
122bcm_systimer_start(struct eventtimer *et, sbintime_t first, sbintime_t period)
123{
124	struct systimer *st = et->et_priv;
125	uint32_t clo, clo1;
126	uint32_t count;
127	register_t s;
128
129	if (first != 0) {
130
131		count = ((uint32_t)et->et_frequency * first) >> 32;
132
133		s = intr_disable();
134		clo = bcm_systimer_tc_read_4(SYSTIMER_CLO);
135restart:
136		clo += count;
137		/*
138		 * Clear pending interrupts
139		 */
140		bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index));
141		bcm_systimer_tc_write_4(SYSTIMER_C0 + st->index*4, clo);
142		clo1 = bcm_systimer_tc_read_4(SYSTIMER_CLO);
143		if ((int32_t)(clo1 - clo) >= 0) {
144			count *= 2;
145			clo = clo1;
146			goto restart;
147		}
148		st->enabled = 1;
149		intr_restore(s);
150
151		return (0);
152	}
153
154	return (EINVAL);
155}
156
157static int
158bcm_systimer_stop(struct eventtimer *et)
159{
160	struct systimer *st = et->et_priv;
161	st->enabled = 0;
162
163	return (0);
164}
165
166static int
167bcm_systimer_intr(void *arg)
168{
169	struct systimer *st = (struct systimer *)arg;
170	uint32_t cs;
171
172 	cs = bcm_systimer_tc_read_4(SYSTIMER_CS);
173	if ((cs & (1 << st->index)) == 0)
174		return (FILTER_STRAY);
175
176	/* ACK interrupt */
177	bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index));
178	if (st->enabled) {
179		if (st->et.et_active) {
180			st->et.et_event_cb(&st->et, st->et.et_arg);
181		}
182	}
183
184	return (FILTER_HANDLED);
185}
186
187static int
188bcm_systimer_probe(device_t dev)
189{
190
191	if (!ofw_bus_status_okay(dev))
192		return (ENXIO);
193
194	if (ofw_bus_is_compatible(dev, "broadcom,bcm2835-system-timer")) {
195		device_set_desc(dev, "BCM2835 System Timer");
196		return (BUS_PROBE_DEFAULT);
197	}
198
199	return (ENXIO);
200}
201
202static int
203bcm_systimer_attach(device_t dev)
204{
205	struct bcm_systimer_softc *sc = device_get_softc(dev);
206	int err;
207	int rid = 0;
208
209	if (bcm_systimer_sc != NULL)
210		return (EINVAL);
211
212	sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE);
213	if (sc->mem_res == NULL) {
214		device_printf(dev, "could not allocate memory resource\n");
215		return (ENXIO);
216	}
217
218	sc->bst = rman_get_bustag(sc->mem_res);
219	sc->bsh = rman_get_bushandle(sc->mem_res);
220
221	/* Request the IRQ resources */
222	err = bus_alloc_resources(dev, bcm_systimer_irq_spec,
223		sc->irq_res);
224	if (err) {
225		device_printf(dev, "Error: could not allocate irq resources\n");
226		return (ENXIO);
227	}
228
229	/* TODO: get frequency from FDT */
230	sc->sysclk_freq = DEFAULT_FREQUENCY;
231
232	/* Setup and enable the timer */
233	if (bus_setup_intr(dev, sc->irq_res[DEFAULT_TIMER], INTR_TYPE_CLK,
234			bcm_systimer_intr, NULL, &sc->st[DEFAULT_TIMER],
235			&sc->intr_hl[DEFAULT_TIMER]) != 0) {
236		bus_release_resources(dev, bcm_systimer_irq_spec,
237			sc->irq_res);
238		device_printf(dev, "Unable to setup the clock irq handler.\n");
239		return (ENXIO);
240	}
241
242	sc->st[DEFAULT_TIMER].index = DEFAULT_TIMER;
243	sc->st[DEFAULT_TIMER].enabled = 0;
244	sc->st[DEFAULT_TIMER].et.et_name = DEFAULT_TIMER_NAME;
245	sc->st[DEFAULT_TIMER].et.et_flags = ET_FLAGS_ONESHOT;
246	sc->st[DEFAULT_TIMER].et.et_quality = 1000;
247	sc->st[DEFAULT_TIMER].et.et_frequency = sc->sysclk_freq;
248	sc->st[DEFAULT_TIMER].et.et_min_period =
249	    (MIN_PERIOD << 32) / sc->st[DEFAULT_TIMER].et.et_frequency + 1;
250	sc->st[DEFAULT_TIMER].et.et_max_period =
251	    (0x7ffffffeLLU << 32) / sc->st[DEFAULT_TIMER].et.et_frequency;
252	sc->st[DEFAULT_TIMER].et.et_start = bcm_systimer_start;
253	sc->st[DEFAULT_TIMER].et.et_stop = bcm_systimer_stop;
254	sc->st[DEFAULT_TIMER].et.et_priv = &sc->st[DEFAULT_TIMER];
255	et_register(&sc->st[DEFAULT_TIMER].et);
256
257	bcm_systimer_sc = sc;
258
259	bcm_systimer_tc.tc_frequency = DEFAULT_FREQUENCY;
260	tc_init(&bcm_systimer_tc);
261
262	return (0);
263}
264
265static device_method_t bcm_systimer_methods[] = {
266	DEVMETHOD(device_probe,		bcm_systimer_probe),
267	DEVMETHOD(device_attach,	bcm_systimer_attach),
268	{ 0, 0 }
269};
270
271static driver_t bcm_systimer_driver = {
272	"systimer",
273	bcm_systimer_methods,
274	sizeof(struct bcm_systimer_softc),
275};
276
277static devclass_t bcm_systimer_devclass;
278
279DRIVER_MODULE(bcm_systimer, simplebus, bcm_systimer_driver, bcm_systimer_devclass, 0, 0);
280
281void
282DELAY(int usec)
283{
284	int32_t counts;
285	uint32_t first, last;
286
287	if (bcm_systimer_sc == NULL) {
288		for (; usec > 0; usec--)
289			for (counts = 200; counts > 0; counts--)
290				/* Prevent gcc from optimizing  out the loop */
291				cpufunc_nullop();
292		return;
293	}
294
295	/* Get the number of times to count */
296	counts = usec * (bcm_systimer_tc.tc_frequency / 1000000) + 1;
297
298	first = bcm_systimer_tc_read_4(SYSTIMER_CLO);
299
300	while (counts > 0) {
301		last = bcm_systimer_tc_read_4(SYSTIMER_CLO);
302		if (last == first)
303			continue;
304		if (last>first) {
305			counts -= (int32_t)(last - first);
306		} else {
307			counts -= (int32_t)((0xFFFFFFFF - first) + last);
308		}
309		first = last;
310	}
311}
312