bcm2835_systimer.c revision 243523 
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: head/sys/arm/broadcom/bcm2835/bcm2835_systimer.c 243523 2012-11-25 16:19:12Z kientzle $");
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/frame.h>
44#include <machine/intr.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#include <machine/fdt.h>
53
54#define	BCM2835_NUM_TIMERS	4
55
56#define	DEFAULT_TIMER		3
57#define	DEFAULT_FREQUENCY	1000000
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, struct bintime *first,
121              struct bintime *period)
122{
123	struct systimer *st = et->et_priv;
124	uint32_t clo;
125	uint32_t count;
126
127	if (first != NULL) {
128		st->enabled = 1;
129
130		count = (st->et.et_frequency * (first->frac >> 32)) >> 32;
131		if (first->sec != 0)
132			count += st->et.et_frequency * first->sec;
133
134		clo = bcm_systimer_tc_read_4(SYSTIMER_CLO);
135		clo += count;
136		bcm_systimer_tc_write_4(SYSTIMER_C0 + st->index*4, clo);
137
138		return (0);
139	}
140
141	return (EINVAL);
142}
143
144static int
145bcm_systimer_stop(struct eventtimer *et)
146{
147	struct systimer *st = et->et_priv;
148	st->enabled = 0;
149
150	return (0);
151}
152
153static int
154bcm_systimer_intr(void *arg)
155{
156	struct systimer *st = (struct systimer *)arg;
157
158	bcm_systimer_tc_write_4(SYSTIMER_CS, (1 << st->index));
159	if (st->enabled) {
160		if (st->et.et_active) {
161			st->et.et_event_cb(&st->et, st->et.et_arg);
162		}
163	}
164
165	return (FILTER_HANDLED);
166}
167
168static int
169bcm_systimer_probe(device_t dev)
170{
171
172	if (ofw_bus_is_compatible(dev, "broadcom,bcm2835-system-timer")) {
173		device_set_desc(dev, "BCM2835 System Timer");
174		return (BUS_PROBE_DEFAULT);
175	}
176
177	return (ENXIO);
178}
179
180static int
181bcm_systimer_attach(device_t dev)
182{
183	struct bcm_systimer_softc *sc = device_get_softc(dev);
184	int err;
185	int rid = 0;
186
187	if (bcm_systimer_sc != NULL)
188		return (EINVAL);
189
190	sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid, RF_ACTIVE);
191	if (sc->mem_res == NULL) {
192		device_printf(dev, "could not allocate memory resource\n");
193		return (ENXIO);
194	}
195
196	sc->bst = rman_get_bustag(sc->mem_res);
197	sc->bsh = rman_get_bushandle(sc->mem_res);
198
199	/* Request the IRQ resources */
200	err = bus_alloc_resources(dev, bcm_systimer_irq_spec,
201		sc->irq_res);
202	if (err) {
203		device_printf(dev, "Error: could not allocate irq resources\n");
204		return (ENXIO);
205	}
206
207	/* TODO: get frequency from FDT */
208	sc->sysclk_freq = DEFAULT_FREQUENCY;
209
210	/* Setup and enable the timer */
211	if (bus_setup_intr(dev, sc->irq_res[DEFAULT_TIMER], INTR_TYPE_CLK,
212			bcm_systimer_intr, NULL, &sc->st[DEFAULT_TIMER],
213			&sc->intr_hl[DEFAULT_TIMER]) != 0) {
214		bus_release_resources(dev, bcm_systimer_irq_spec,
215			sc->irq_res);
216		device_printf(dev, "Unable to setup the clock irq handler.\n");
217		return (ENXIO);
218	}
219
220	sc->st[DEFAULT_TIMER].index = DEFAULT_TIMER;
221	sc->st[DEFAULT_TIMER].enabled = 0;
222	sc->st[DEFAULT_TIMER].et.et_name = malloc(64, M_DEVBUF, M_NOWAIT | M_ZERO);
223	sprintf(sc->st[DEFAULT_TIMER].et.et_name, "BCM2835 Event Timer %d", DEFAULT_TIMER);
224	sc->st[DEFAULT_TIMER].et.et_flags = ET_FLAGS_ONESHOT;
225	sc->st[DEFAULT_TIMER].et.et_quality = 1000;
226	sc->st[DEFAULT_TIMER].et.et_frequency = sc->sysclk_freq;
227	sc->st[DEFAULT_TIMER].et.et_min_period.sec = 0;
228	sc->st[DEFAULT_TIMER].et.et_min_period.frac =
229	    ((0x00000002LLU << 32) / sc->st[DEFAULT_TIMER].et.et_frequency) << 32;
230	sc->st[DEFAULT_TIMER].et.et_max_period.sec = 0xfffffff0U / sc->st[DEFAULT_TIMER].et.et_frequency;
231	sc->st[DEFAULT_TIMER].et.et_max_period.frac =
232	    ((0xfffffffeLLU << 32) / sc->st[DEFAULT_TIMER].et.et_frequency) << 32;
233	sc->st[DEFAULT_TIMER].et.et_start = bcm_systimer_start;
234	sc->st[DEFAULT_TIMER].et.et_stop = bcm_systimer_stop;
235	sc->st[DEFAULT_TIMER].et.et_priv = &sc->st[DEFAULT_TIMER];
236	et_register(&sc->st[DEFAULT_TIMER].et);
237
238	bcm_systimer_sc = sc;
239
240	bcm_systimer_tc.tc_frequency = DEFAULT_FREQUENCY;
241	tc_init(&bcm_systimer_tc);
242
243	return (0);
244}
245
246static device_method_t bcm_systimer_methods[] = {
247	DEVMETHOD(device_probe,		bcm_systimer_probe),
248	DEVMETHOD(device_attach,	bcm_systimer_attach),
249	{ 0, 0 }
250};
251
252static driver_t bcm_systimer_driver = {
253	"systimer",
254	bcm_systimer_methods,
255	sizeof(struct bcm_systimer_softc),
256};
257
258static devclass_t bcm_systimer_devclass;
259
260DRIVER_MODULE(bcm_systimer, simplebus, bcm_systimer_driver, bcm_systimer_devclass, 0, 0);
261
262void
263cpu_initclocks(void)
264{
265	cpu_initclocks_bsp();
266}
267
268void
269DELAY(int usec)
270{
271	int32_t counts;
272	uint32_t first, last;
273
274	if (bcm_systimer_sc == NULL) {
275		for (; usec > 0; usec--)
276			for (counts = 200; counts > 0; counts--)
277				/* Prevent gcc from optimizing  out the loop */
278				cpufunc_nullop();
279		return;
280	}
281
282	/* Get the number of times to count */
283	counts = usec * ((bcm_systimer_tc.tc_frequency / 1000000) + 1);
284
285	first = bcm_systimer_tc_read_4(SYSTIMER_CLO);
286
287	while (counts > 0) {
288		last = bcm_systimer_tc_read_4(SYSTIMER_CLO);
289		if (last == first)
290			continue;
291		if (last>first) {
292			counts -= (int32_t)(last - first);
293		} else {
294			counts -= (int32_t)((0xFFFFFFFF - first) + last);
295		}
296		first = last;
297	}
298}
299