1 /* $NetBSD: bcm2835_tmr.c,v 1.12 2021/01/29 14:11:14 skrll Exp $ */
2
3 /*-
4 * Copyright (c) 2012 The NetBSD Foundation, Inc.
5 * All rights reserved.
6 *
7 * This code is derived from software contributed to The NetBSD Foundation
8 * by Nick Hudson
9 *
10 * Redistribution and use in source and binary forms, with or without
11 * modification, are permitted provided that the following conditions
12 * are met:
13 * 1. Redistributions of source code must retain the above copyright
14 * notice, this list of conditions and the following disclaimer.
15 * 2. Redistributions in binary form must reproduce the above copyright
16 * notice, this list of conditions and the following disclaimer in the
17 * documentation and/or other materials provided with the distribution.
18 *
19 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
20 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
21 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
22 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
23 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
24 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
25 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
26 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
27 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
28 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
29 * POSSIBILITY OF SUCH DAMAGE.
30 */
31
32 #include <sys/cdefs.h>
33 __KERNEL_RCSID(0, "$NetBSD: bcm2835_tmr.c,v 1.12 2021/01/29 14:11:14 skrll Exp $");
34
35 #include <sys/param.h>
36 #include <sys/systm.h>
37 #include <sys/device.h>
38 #include <sys/kernel.h>
39 #include <sys/timetc.h>
40 #include <sys/bus.h>
41
42 #include <arm/broadcom/bcm2835_intr.h>
43 #include <arm/broadcom/bcm2835reg.h>
44 #include <arm/broadcom/bcm2835var.h>
45
46 #include <dev/fdt/fdtvar.h>
47
48 #include <arm/fdt/arm_fdtvar.h>
49
50 /* Use the 3rd timer*/
51 #define BCMTIMER 3
52
53 #define BCM2835_STIMER_CS 0x00
54 #define BCM2835_STIMER_M0 __BIT(0)
55 #define BCM2835_STIMER_M1 __BIT(1)
56 #define BCM2835_STIMER_M2 __BIT(2)
57 #define BCM2835_STIMER_M3 __BIT(3)
58 #define BCM2835_STIMER_CLO 0x04
59 #define BCM2835_STIMER_CHI 0x08
60 #define BCM2835_STIMER_C0 0x0c
61 #define BCM2835_STIMER_C1 0x10
62 #define BCM2835_STIMER_C2 0x14
63 #define BCM2835_STIMER_C3 0x18
64
65 #define BCM2835_STIMER_HZ 1000000
66
67 static const uint32_t counts_per_usec = (BCM2835_STIMER_HZ / 1000000);
68 static uint32_t counts_per_hz = ~0;
69
70 struct bcm2835tmr_softc {
71 device_t sc_dev;
72
73 bus_space_tag_t sc_iot;
74 bus_space_handle_t sc_ioh;
75
76 void *sc_ih;
77 };
78
79 static int bcmtmr_match(device_t, cfdata_t, void *);
80 static void bcmtmr_attach(device_t, device_t, void *);
81
82 static int clockhandler(void *);
83
84 static u_int bcm2835tmr_get_timecount(struct timecounter *);
85 void bcm2835_tmr_setstatclockrate(int);
86
87 static struct bcm2835tmr_softc *bcm2835tmr_sc;
88
89 static struct timecounter bcm2835tmr_timecounter = {
90 .tc_get_timecount = bcm2835tmr_get_timecount,
91 .tc_poll_pps = 0,
92 .tc_counter_mask = ~0u,
93 .tc_frequency = BCM2835_STIMER_HZ,
94 .tc_name = NULL, /* set by attach */
95 .tc_quality = 100,
96 .tc_priv = NULL,
97 .tc_next = NULL,
98 };
99
100 CFATTACH_DECL_NEW(bcmtmr_fdt, sizeof(struct bcm2835tmr_softc),
101 bcmtmr_match, bcmtmr_attach, NULL, NULL);
102
103 static const struct device_compatible_entry compat_data[] = {
104 { .compat = "brcm,bcm2835-system-timer" },
105 DEVICE_COMPAT_EOL
106 };
107
108 /* ARGSUSED */
109 static int
bcmtmr_match(device_t parent,cfdata_t match,void * aux)110 bcmtmr_match(device_t parent, cfdata_t match, void *aux)
111 {
112 struct fdt_attach_args * const faa = aux;
113
114 return of_compatible_match(faa->faa_phandle, compat_data);
115 }
116
117 static void
bcmtmr_attach(device_t parent,device_t self,void * aux)118 bcmtmr_attach(device_t parent, device_t self, void *aux)
119 {
120 struct bcm2835tmr_softc *sc = device_private(self);
121 struct fdt_attach_args * const faa = aux;
122
123 aprint_naive("\n");
124 aprint_normal(": VC System Timer\n");
125
126 if (bcm2835tmr_sc == NULL)
127 bcm2835tmr_sc = sc;
128
129 sc->sc_dev = self;
130 sc->sc_iot = faa->faa_bst;
131 const int phandle = faa->faa_phandle;
132
133 bus_addr_t addr;
134 bus_size_t size;
135
136 if (fdtbus_get_reg(phandle, 0, &addr, &size) != 0) {
137 aprint_error(": missing 'reg' property\n");
138 return;
139 }
140
141 if (bus_space_map(sc->sc_iot, addr, size, 0, &sc->sc_ioh) != 0) {
142 aprint_error_dev(sc->sc_dev, "unable to map device\n");
143 return;
144 }
145
146 char intrstr[128];
147 if (!fdtbus_intr_str(phandle, BCMTIMER, intrstr, sizeof(intrstr))) {
148 aprint_error(": failed to decode interrupt\n");
149 return;
150 }
151
152 sc->sc_ih = fdtbus_intr_establish_xname(phandle, BCMTIMER, IPL_CLOCK,
153 FDT_INTR_MPSAFE, clockhandler, NULL, device_xname(self));
154 if (sc->sc_ih == NULL) {
155 aprint_error(": failed to establish interrupt on %s\n",
156 intrstr);
157 return;
158 }
159 aprint_normal_dev(self, "interrupting on %s\n", intrstr);
160
161 bcm2835tmr_timecounter.tc_name = device_xname(self);
162 }
163
164 void
cpu_initclocks(void)165 cpu_initclocks(void)
166 {
167 struct bcm2835tmr_softc *sc = bcm2835tmr_sc;
168 uint32_t stcl;
169
170 KASSERT(sc != NULL);
171
172 bcm2835tmr_timecounter.tc_priv = sc;
173
174 counts_per_hz = BCM2835_STIMER_HZ / hz;
175
176 stcl = bus_space_read_4(sc->sc_iot, sc->sc_ioh, BCM2835_STIMER_CLO);
177 stcl += counts_per_hz;
178
179 bus_space_write_4(sc->sc_iot, sc->sc_ioh, BCM2835_STIMER_C3, stcl);
180
181 tc_init(&bcm2835tmr_timecounter);
182 }
183
184 void
bcm2835_tmr_delay(unsigned int n)185 bcm2835_tmr_delay(unsigned int n)
186 {
187 struct bcm2835tmr_softc *sc = bcm2835tmr_sc;
188 uint32_t last, curr;
189 uint32_t delta, usecs;
190
191 KASSERT(sc != NULL);
192
193 last = bus_space_read_4(sc->sc_iot, sc->sc_ioh, BCM2835_STIMER_CLO);
194
195 delta = usecs = 0;
196 while (n > usecs) {
197 curr = bus_space_read_4(sc->sc_iot, sc->sc_ioh,
198 BCM2835_STIMER_CLO);
199
200 /* Check to see if the timer has wrapped around. */
201 if (curr < last)
202 delta += curr + (UINT32_MAX - last);
203 else
204 delta += curr - last;
205
206 last = curr;
207
208 if (delta >= counts_per_usec) {
209 usecs += delta / counts_per_usec;
210 delta %= counts_per_usec;
211 }
212 }
213 }
214
215 /*
216 * clockhandler:
217 *
218 * Handle the hardclock interrupt.
219 */
220 static int
clockhandler(void * arg)221 clockhandler(void *arg)
222 {
223 struct bcm2835tmr_softc *sc = bcm2835tmr_sc;
224 struct clockframe *frame = arg;
225 uint32_t curr, status;
226
227 status = bus_space_read_4(sc->sc_iot, sc->sc_ioh,
228 BCM2835_STIMER_CS);
229
230 if (!(status & BCM2835_STIMER_M3))
231 return 0;
232
233 bus_space_write_4(sc->sc_iot, sc->sc_ioh, BCM2835_STIMER_CS,
234 BCM2835_STIMER_M3);
235
236 hardclock(frame);
237
238 curr = bus_space_read_4(sc->sc_iot, sc->sc_ioh, BCM2835_STIMER_CLO);
239
240 curr += counts_per_hz;
241 bus_space_write_4(sc->sc_iot, sc->sc_ioh, BCM2835_STIMER_C3, curr);
242
243 return 1;
244 }
245
246 void
setstatclockrate(int newhz)247 setstatclockrate(int newhz)
248 {
249 }
250
251 static u_int
bcm2835tmr_get_timecount(struct timecounter * tc)252 bcm2835tmr_get_timecount(struct timecounter *tc)
253 {
254 struct bcm2835tmr_softc *sc = tc->tc_priv;
255
256 return bus_space_read_4(sc->sc_iot, sc->sc_ioh, BCM2835_STIMER_CLO);
257 }
258
259