1 /*-
2 * Copyright (c) 2017 Andrew Turner
3 * All rights reserved.
4 *
5 * This software was developed by SRI International and the University of
6 * Cambridge Computer Laboratory under DARPA/AFRL contract FA8750-10-C-0237
7 * ("CTSRD"), as part of the DARPA CRASH research programme.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
19 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
20 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
21 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
22 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
23 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
24 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
25 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
26 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
27 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28 * SUCH DAMAGE.
29 */
30
31 #include <sys/param.h>
32 #include <sys/systm.h>
33 #include <sys/bus.h>
34 #include <sys/clock.h>
35 #include <sys/efi.h>
36 #include <sys/kernel.h>
37 #include <sys/module.h>
38
39 #include "clock_if.h"
40
41 static bool efirtc_zeroes_subseconds;
42 static struct timespec efirtc_resadj;
43
44 static const u_int us_per_s = 1000000;
45 static const u_int ns_per_s = 1000000000;
46 static const u_int ns_per_us = 1000;
47
48 static void
efirtc_identify(driver_t * driver,device_t parent)49 efirtc_identify(driver_t *driver, device_t parent)
50 {
51
52 /* Don't add the driver unless we have working runtime services. */
53 if (efi_rt_ok() != 0)
54 return;
55 if (device_find_child(parent, "efirtc", -1) != NULL)
56 return;
57 if (BUS_ADD_CHILD(parent, 0, "efirtc", -1) == NULL)
58 device_printf(parent, "add child failed\n");
59 }
60
61 static int
efirtc_probe(device_t dev)62 efirtc_probe(device_t dev)
63 {
64 struct efi_tm tm;
65 int error;
66
67 /*
68 * Check whether we can read the time. This will stop us from attaching
69 * when there is EFI Runtime support but the gettime function is
70 * unimplemented, e.g. on some builds of U-Boot.
71 */
72 if ((error = efi_get_time(&tm)) != 0) {
73 if (bootverbose)
74 device_printf(dev, "cannot read EFI realtime clock, "
75 "error %d\n", error);
76 return (error);
77 }
78 device_set_desc(dev, "EFI Realtime Clock");
79 return (BUS_PROBE_DEFAULT);
80 }
81
82 static int
efirtc_attach(device_t dev)83 efirtc_attach(device_t dev)
84 {
85 struct efi_tmcap tmcap;
86 long res;
87 int error;
88
89 bzero(&tmcap, sizeof(tmcap));
90 if ((error = efi_get_time_capabilities(&tmcap)) != 0) {
91 device_printf(dev, "cannot get EFI time capabilities");
92 return (error);
93 }
94
95 /* Translate resolution in Hz to tick length in usec. */
96 if (tmcap.tc_res == 0)
97 res = us_per_s; /* 0 is insane, assume 1 Hz. */
98 else if (tmcap.tc_res > us_per_s)
99 res = 1; /* 1us is the best we can represent */
100 else
101 res = us_per_s / tmcap.tc_res;
102
103 /* Clock rounding adjustment is 1/2 of resolution, in nsec. */
104 efirtc_resadj.tv_nsec = (res * ns_per_us) / 2;
105
106 /* Does the clock zero the subseconds when time is set? */
107 efirtc_zeroes_subseconds = tmcap.tc_stz;
108
109 /*
110 * Register. If the clock zeroes out the subseconds when it's set,
111 * schedule the SetTime calls to happen just before top-of-second.
112 */
113 clock_register_flags(dev, res, CLOCKF_SETTIME_NO_ADJ);
114 if (efirtc_zeroes_subseconds)
115 clock_schedule(dev, ns_per_s - ns_per_us);
116
117 return (0);
118 }
119
120 static int
efirtc_detach(device_t dev)121 efirtc_detach(device_t dev)
122 {
123
124 clock_unregister(dev);
125 return (0);
126 }
127
128 static int
efirtc_gettime(device_t dev,struct timespec * ts)129 efirtc_gettime(device_t dev, struct timespec *ts)
130 {
131 struct clocktime ct;
132 struct efi_tm tm;
133 int error;
134
135 error = efi_get_time(&tm);
136 if (error != 0)
137 return (error);
138
139 ct.sec = tm.tm_sec;
140 ct.min = tm.tm_min;
141 ct.hour = tm.tm_hour;
142 ct.day = tm.tm_mday;
143 ct.mon = tm.tm_mon;
144 ct.year = tm.tm_year;
145 ct.nsec = tm.tm_nsec;
146
147 clock_dbgprint_ct(dev, CLOCK_DBG_READ, &ct);
148 return (clock_ct_to_ts(&ct, ts));
149 }
150
151 static int
efirtc_settime(device_t dev,struct timespec * ts)152 efirtc_settime(device_t dev, struct timespec *ts)
153 {
154 struct clocktime ct;
155 struct efi_tm tm;
156
157 /*
158 * We request a timespec with no resolution-adjustment so that we can
159 * apply it ourselves based on whether or not the clock zeroes the
160 * sub-second part of the time when setting the time.
161 */
162 ts->tv_sec -= utc_offset();
163 if (!efirtc_zeroes_subseconds)
164 timespecadd(ts, &efirtc_resadj, ts);
165
166 clock_ts_to_ct(ts, &ct);
167 clock_dbgprint_ct(dev, CLOCK_DBG_WRITE, &ct);
168
169 bzero(&tm, sizeof(tm));
170 tm.tm_sec = ct.sec;
171 tm.tm_min = ct.min;
172 tm.tm_hour = ct.hour;
173 tm.tm_mday = ct.day;
174 tm.tm_mon = ct.mon;
175 tm.tm_year = ct.year;
176 tm.tm_nsec = ct.nsec;
177
178 return (efi_set_time(&tm));
179 }
180
181 static device_method_t efirtc_methods[] = {
182 /* Device interface */
183 DEVMETHOD(device_identify, efirtc_identify),
184 DEVMETHOD(device_probe, efirtc_probe),
185 DEVMETHOD(device_attach, efirtc_attach),
186 DEVMETHOD(device_detach, efirtc_detach),
187
188 /* Clock interface */
189 DEVMETHOD(clock_gettime, efirtc_gettime),
190 DEVMETHOD(clock_settime, efirtc_settime),
191
192 DEVMETHOD_END
193 };
194
195 static driver_t efirtc_driver = {
196 "efirtc",
197 efirtc_methods,
198 0
199 };
200
201 DRIVER_MODULE(efirtc, nexus, efirtc_driver, 0, 0);
202 MODULE_VERSION(efirtc, 1);
203 MODULE_DEPEND(efirtc, efirt, 1, 1, 1);
204