at91_pit.c revision 237115 
1/*-
2 * Copyright (c) 2009 Gallon Sylvestre.  All rights reserved.
3 * Copyright (c) 2010 Greg Ansley.  All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26
27#include <sys/cdefs.h>
28__FBSDID("$FreeBSD: head/sys/arm/at91/at91_pit.c 237115 2012-06-15 06:38:55Z imp $");
29
30#include <sys/param.h>
31#include <sys/bus.h>
32#include <sys/kernel.h>
33#include <sys/module.h>
34#include <sys/resource.h>
35#include <sys/systm.h>
36#include <sys/rman.h>
37#include <sys/time.h>
38#include <sys/timetc.h>
39#include <sys/watchdog.h>
40
41#include <machine/bus.h>
42#include <machine/cpu.h>
43#include <machine/cpufunc.h>
44#include <machine/frame.h>
45#include <machine/intr.h>
46#include <machine/resource.h>
47
48#include <arm/at91/at91var.h>
49#include <arm/at91/at91_pitreg.h>
50
51static struct pit_softc {
52	struct resource	*mem_res;	/* Memory resource */
53	void		*intrhand;	/* Interrupt handle */
54	device_t	sc_dev;
55} *sc;
56
57static uint32_t timecount = 0;
58
59static inline uint32_t
60RD4(struct pit_softc *sc, bus_size_t off)
61{
62
63	return (bus_read_4(sc->mem_res, off));
64}
65
66static inline void
67WR4(struct pit_softc *sc, bus_size_t off, uint32_t val)
68{
69
70	bus_write_4(sc->mem_res, off, val);
71}
72
73static unsigned at91pit_get_timecount(struct timecounter *tc);
74static int pit_intr(void *arg);
75
76#ifndef PIT_PRESCALE
77#define PIT_PRESCALE (16)
78#endif
79
80static struct timecounter at91pit_timecounter = {
81	at91pit_get_timecount, /* get_timecount */
82	NULL, /* no poll_pps */
83	0xffffffff, /* counter mask */
84	0 / PIT_PRESCALE, /* frequency */
85	"AT91SAM9 timer", /* name */
86	1000 /* quality */
87};
88
89static int
90at91pit_probe(device_t dev)
91{
92
93	if (at91_is_sam9() || at91_is_sam9xe()) {
94		device_set_desc(dev, "AT91SAM9 PIT");
95		return (0);
96	}
97	return (ENXIO);
98}
99
100static int
101at91pit_attach(device_t dev)
102{
103	void *ih;
104	int rid, err = 0;
105	struct at91_softc *at91_sc;
106	struct resource *irq;
107
108	at91_sc = device_get_softc(device_get_parent(dev));
109	sc = device_get_softc(dev);
110	sc->sc_dev = dev;
111
112	rid = 0;
113	sc->mem_res = bus_alloc_resource_any(dev, SYS_RES_MEMORY, &rid,
114	    RF_ACTIVE);
115
116	if (sc->mem_res == NULL)
117		panic("couldn't allocate register resources");
118
119	rid = 0;
120	irq = bus_alloc_resource(dev, SYS_RES_IRQ, &rid, 1, 1, 1,
121	    RF_ACTIVE | RF_SHAREABLE);
122	if (!irq) {
123		device_printf(dev, "could not allocate interrupt resources.\n");
124		err = ENOMEM;
125		goto out;
126	}
127
128	/* Activate the interrupt. */
129	err = bus_setup_intr(dev, irq, INTR_TYPE_CLK, pit_intr, NULL, NULL,
130	    &ih);
131
132	at91pit_timecounter.tc_frequency =  at91_master_clock / PIT_PRESCALE;
133	tc_init(&at91pit_timecounter);
134
135	/* Enable the PIT here. */
136	WR4(sc, PIT_MR, PIT_PIV(at91_master_clock / PIT_PRESCALE / hz) |
137	    PIT_EN | PIT_IEN);
138out:
139	return (err);
140}
141
142static device_method_t at91pit_methods[] = {
143	DEVMETHOD(device_probe, at91pit_probe),
144	DEVMETHOD(device_attach, at91pit_attach),
145	DEVMETHOD_END
146};
147
148static driver_t at91pit_driver = {
149	"at91_pit",
150	at91pit_methods,
151	sizeof(struct pit_softc),
152};
153
154static devclass_t at91pit_devclass;
155
156DRIVER_MODULE(at91_pit, atmelarm, at91pit_driver, at91pit_devclass, NULL,
157    NULL);
158
159static int
160pit_intr(void *arg)
161{
162	struct trapframe *fp = arg;
163	uint32_t icnt;
164
165	if (RD4(sc, PIT_SR) & PIT_PITS_DONE) {
166		icnt = RD4(sc, PIT_PIVR) >> 20;
167
168		/* Just add in the overflows we just read */
169		timecount +=  PIT_PIV(RD4(sc, PIT_MR)) * icnt;
170
171		hardclock(TRAPF_USERMODE(fp), TRAPF_PC(fp));
172		return (FILTER_HANDLED);
173	}
174	return (FILTER_STRAY);
175}
176
177static unsigned
178at91pit_get_timecount(struct timecounter *tc)
179{
180	uint32_t piir, icnt;
181
182	piir = RD4(sc, PIT_PIIR); /* Current  count | over flows */
183	icnt = piir >> 20;	/* Overflows */
184	return (timecount + PIT_PIV(piir) + PIT_PIV(RD4(sc, PIT_MR)) * icnt);
185}
186
187void
188DELAY(int us)
189{
190	int32_t cnt, last, piv;
191	uint64_t pit_freq;
192	const uint64_t mhz  = 1E6;
193
194	last = PIT_PIV(RD4(sc, PIT_PIIR));
195
196	/* Max delay ~= 260s. @ 133Mhz */
197	pit_freq = at91_master_clock / PIT_PRESCALE;
198	cnt  = ((pit_freq * us) + (mhz -1)) / mhz;
199	cnt  = (cnt <= 0) ? 1 : cnt;
200
201	while (cnt > 0) {
202		piv = PIT_PIV(RD4(sc, PIT_PIIR));
203			cnt  -= piv - last ;
204		if (piv < last)
205			cnt -= PIT_PIV(~0u) - last;
206		last = piv;
207	}
208}
209