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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/arch/parisc/kernel/time.c
4 *
5 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
6 * Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King
7 * Copyright (C) 1999 SuSE GmbH, (Philipp Rumpf, prumpf@tux.org)
8 *
9 * 1994-07-02 Alan Modra
10 * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
11 * 1998-12-20 Updated NTP code according to technical memorandum Jan '96
12 * "A Kernel Model for Precision Timekeeping" by Dave Mills
13 */
14#include <linux/errno.h>
15#include <linux/module.h>
16#include <linux/rtc.h>
17#include <linux/sched.h>
18#include <linux/sched/clock.h>
19#include <linux/sched_clock.h>
20#include <linux/kernel.h>
21#include <linux/param.h>
22#include <linux/string.h>
23#include <linux/mm.h>
24#include <linux/interrupt.h>
25#include <linux/time.h>
26#include <linux/init.h>
27#include <linux/smp.h>
28#include <linux/profile.h>
29#include <linux/clocksource.h>
30#include <linux/platform_device.h>
31#include <linux/ftrace.h>
32
33#include <linux/uaccess.h>
34#include <asm/io.h>
35#include <asm/irq.h>
36#include <asm/page.h>
37#include <asm/param.h>
38#include <asm/pdc.h>
39#include <asm/led.h>
40
41#include <linux/timex.h>
42
43static unsigned long clocktick __ro_after_init; /* timer cycles per tick */
44
45/*
46 * We keep time on PA-RISC Linux by using the Interval Timer which is
47 * a pair of registers; one is read-only and one is write-only; both
48 * accessed through CR16. The read-only register is 32 or 64 bits wide,
49 * and increments by 1 every CPU clock tick. The architecture only
50 * guarantees us a rate between 0.5 and 2, but all implementations use a
51 * rate of 1. The write-only register is 32-bits wide. When the lowest
52 * 32 bits of the read-only register compare equal to the write-only
53 * register, it raises a maskable external interrupt. Each processor has
54 * an Interval Timer of its own and they are not synchronised.
55 *
56 * We want to generate an interrupt every 1/HZ seconds. So we program
57 * CR16 to interrupt every @clocktick cycles. The it_value in cpu_data
58 * is programmed with the intended time of the next tick. We can be
59 * held off for an arbitrarily long period of time by interrupts being
60 * disabled, so we may miss one or more ticks.
61 */
62irqreturn_t __irq_entry timer_interrupt(int irq, void *dev_id)
63{
64 unsigned long now;
65 unsigned long next_tick;
66 unsigned long ticks_elapsed = 0;
67 unsigned int cpu = smp_processor_id();
68 struct cpuinfo_parisc *cpuinfo = &per_cpu(cpu_data, cpu);
69
70 /* gcc can optimize for "read-only" case with a local clocktick */
71 unsigned long cpt = clocktick;
72
73 profile_tick(CPU_PROFILING);
74
75 /* Initialize next_tick to the old expected tick time. */
76 next_tick = cpuinfo->it_value;
77
78 /* Calculate how many ticks have elapsed. */
79 now = mfctl(16);
80 do {
81 ++ticks_elapsed;
82 next_tick += cpt;
83 } while (next_tick - now > cpt);
84
85 /* Store (in CR16 cycles) up to when we are accounting right now. */
86 cpuinfo->it_value = next_tick;
87
88 /* Go do system house keeping. */
89 if (cpu == 0)
90 xtime_update(ticks_elapsed);
91
92 update_process_times(user_mode(get_irq_regs()));
93
94 /* Skip clockticks on purpose if we know we would miss those.
95 * The new CR16 must be "later" than current CR16 otherwise
96 * itimer would not fire until CR16 wrapped - e.g 4 seconds
97 * later on a 1Ghz processor. We'll account for the missed
98 * ticks on the next timer interrupt.
99 * We want IT to fire modulo clocktick even if we miss/skip some.
100 * But those interrupts don't in fact get delivered that regularly.
101 *
102 * "next_tick - now" will always give the difference regardless
103 * if one or the other wrapped. If "now" is "bigger" we'll end up
104 * with a very large unsigned number.
105 */
106 now = mfctl(16);
107 while (next_tick - now > cpt)
108 next_tick += cpt;
109
110 /* Program the IT when to deliver the next interrupt.
111 * Only bottom 32-bits of next_tick are writable in CR16!
112 * Timer interrupt will be delivered at least a few hundred cycles
113 * after the IT fires, so if we are too close (<= 8000 cycles) to the
114 * next cycle, simply skip it.
115 */
116 if (next_tick - now <= 8000)
117 next_tick += cpt;
118 mtctl(next_tick, 16);
119
120 return IRQ_HANDLED;
121}
122
123
124unsigned long profile_pc(struct pt_regs *regs)
125{
126 unsigned long pc = instruction_pointer(regs);
127
128 if (regs->gr[0] & PSW_N)
129 pc -= 4;
130
131#ifdef CONFIG_SMP
132 if (in_lock_functions(pc))
133 pc = regs->gr[2];
134#endif
135
136 return pc;
137}
138EXPORT_SYMBOL(profile_pc);
139
140
141/* clock source code */
142
143static u64 notrace read_cr16(struct clocksource *cs)
144{
145 return get_cycles();
146}
147
148static struct clocksource clocksource_cr16 = {
149 .name = "cr16",
150 .rating = 300,
151 .read = read_cr16,
152 .mask = CLOCKSOURCE_MASK(BITS_PER_LONG),
153 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
154};
155
156void __init start_cpu_itimer(void)
157{
158 unsigned int cpu = smp_processor_id();
159 unsigned long next_tick = mfctl(16) + clocktick;
160
161 mtctl(next_tick, 16); /* kick off Interval Timer (CR16) */
162
163 per_cpu(cpu_data, cpu).it_value = next_tick;
164}
165
166#if IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
167static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
168{
169 struct pdc_tod tod_data;
170
171 memset(tm, 0, sizeof(*tm));
172 if (pdc_tod_read(&tod_data) < 0)
173 return -EOPNOTSUPP;
174
175 /* we treat tod_sec as unsigned, so this can work until year 2106 */
176 rtc_time64_to_tm(tod_data.tod_sec, tm);
177 return 0;
178}
179
180static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm)
181{
182 time64_t secs = rtc_tm_to_time64(tm);
183
184 if (pdc_tod_set(secs, 0) < 0)
185 return -EOPNOTSUPP;
186
187 return 0;
188}
189
190static const struct rtc_class_ops rtc_generic_ops = {
191 .read_time = rtc_generic_get_time,
192 .set_time = rtc_generic_set_time,
193};
194
195static int __init rtc_init(void)
196{
197 struct platform_device *pdev;
198
199 pdev = platform_device_register_data(NULL, "rtc-generic", -1,
200 &rtc_generic_ops,
201 sizeof(rtc_generic_ops));
202
203 return PTR_ERR_OR_ZERO(pdev);
204}
205device_initcall(rtc_init);
206#endif
207
208void read_persistent_clock64(struct timespec64 *ts)
209{
210 static struct pdc_tod tod_data;
211 if (pdc_tod_read(&tod_data) == 0) {
212 ts->tv_sec = tod_data.tod_sec;
213 ts->tv_nsec = tod_data.tod_usec * 1000;
214 } else {
215 printk(KERN_ERR "Error reading tod clock\n");
216 ts->tv_sec = 0;
217 ts->tv_nsec = 0;
218 }
219}
220
221
222static u64 notrace read_cr16_sched_clock(void)
223{
224 return get_cycles();
225}
226
227
228/*
229 * timer interrupt and sched_clock() initialization
230 */
231
232void __init time_init(void)
233{
234 unsigned long cr16_hz;
235
236 clocktick = (100 * PAGE0->mem_10msec) / HZ;
237 start_cpu_itimer(); /* get CPU 0 started */
238
239 cr16_hz = 100 * PAGE0->mem_10msec; /* Hz */
240
241 /* register as sched_clock source */
242 sched_clock_register(read_cr16_sched_clock, BITS_PER_LONG, cr16_hz);
243}
244
245static int __init init_cr16_clocksource(void)
246{
247 /*
248 * The cr16 interval timers are not syncronized across CPUs on
249 * different sockets, so mark them unstable and lower rating on
250 * multi-socket SMP systems.
251 */
252 if (num_online_cpus() > 1 && !running_on_qemu) {
253 int cpu;
254 unsigned long cpu0_loc;
255 cpu0_loc = per_cpu(cpu_data, 0).cpu_loc;
256
257 for_each_online_cpu(cpu) {
258 if (cpu == 0)
259 continue;
260 if ((cpu0_loc != 0) &&
261 (cpu0_loc == per_cpu(cpu_data, cpu).cpu_loc))
262 continue;
263
264 clocksource_cr16.name = "cr16_unstable";
265 clocksource_cr16.flags = CLOCK_SOURCE_UNSTABLE;
266 clocksource_cr16.rating = 0;
267 break;
268 }
269 }
270
271 /* XXX: We may want to mark sched_clock stable here if cr16 clocks are
272 * in sync:
273 * (clocksource_cr16.flags == CLOCK_SOURCE_IS_CONTINUOUS) */
274
275 /* register at clocksource framework */
276 clocksource_register_hz(&clocksource_cr16,
277 100 * PAGE0->mem_10msec);
278
279 return 0;
280}
281
282device_initcall(init_cr16_clocksource);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/arch/parisc/kernel/time.c
4 *
5 * Copyright (C) 1991, 1992, 1995 Linus Torvalds
6 * Modifications for ARM (C) 1994, 1995, 1996,1997 Russell King
7 * Copyright (C) 1999 SuSE GmbH, (Philipp Rumpf, prumpf@tux.org)
8 *
9 * 1994-07-02 Alan Modra
10 * fixed set_rtc_mmss, fixed time.year for >= 2000, new mktime
11 * 1998-12-20 Updated NTP code according to technical memorandum Jan '96
12 * "A Kernel Model for Precision Timekeeping" by Dave Mills
13 */
14#include <linux/errno.h>
15#include <linux/module.h>
16#include <linux/rtc.h>
17#include <linux/sched.h>
18#include <linux/sched/clock.h>
19#include <linux/sched_clock.h>
20#include <linux/kernel.h>
21#include <linux/param.h>
22#include <linux/string.h>
23#include <linux/mm.h>
24#include <linux/interrupt.h>
25#include <linux/time.h>
26#include <linux/init.h>
27#include <linux/smp.h>
28#include <linux/profile.h>
29#include <linux/clocksource.h>
30#include <linux/platform_device.h>
31#include <linux/ftrace.h>
32
33#include <linux/uaccess.h>
34#include <asm/io.h>
35#include <asm/irq.h>
36#include <asm/page.h>
37#include <asm/param.h>
38#include <asm/pdc.h>
39#include <asm/led.h>
40
41#include <linux/timex.h>
42
43int time_keeper_id __read_mostly; /* CPU used for timekeeping. */
44
45static unsigned long clocktick __ro_after_init; /* timer cycles per tick */
46
47/*
48 * We keep time on PA-RISC Linux by using the Interval Timer which is
49 * a pair of registers; one is read-only and one is write-only; both
50 * accessed through CR16. The read-only register is 32 or 64 bits wide,
51 * and increments by 1 every CPU clock tick. The architecture only
52 * guarantees us a rate between 0.5 and 2, but all implementations use a
53 * rate of 1. The write-only register is 32-bits wide. When the lowest
54 * 32 bits of the read-only register compare equal to the write-only
55 * register, it raises a maskable external interrupt. Each processor has
56 * an Interval Timer of its own and they are not synchronised.
57 *
58 * We want to generate an interrupt every 1/HZ seconds. So we program
59 * CR16 to interrupt every @clocktick cycles. The it_value in cpu_data
60 * is programmed with the intended time of the next tick. We can be
61 * held off for an arbitrarily long period of time by interrupts being
62 * disabled, so we may miss one or more ticks.
63 */
64irqreturn_t __irq_entry timer_interrupt(int irq, void *dev_id)
65{
66 unsigned long now;
67 unsigned long next_tick;
68 unsigned long ticks_elapsed = 0;
69 unsigned int cpu = smp_processor_id();
70 struct cpuinfo_parisc *cpuinfo = &per_cpu(cpu_data, cpu);
71
72 /* gcc can optimize for "read-only" case with a local clocktick */
73 unsigned long cpt = clocktick;
74
75 /* Initialize next_tick to the old expected tick time. */
76 next_tick = cpuinfo->it_value;
77
78 /* Calculate how many ticks have elapsed. */
79 now = mfctl(16);
80 do {
81 ++ticks_elapsed;
82 next_tick += cpt;
83 } while (next_tick - now > cpt);
84
85 /* Store (in CR16 cycles) up to when we are accounting right now. */
86 cpuinfo->it_value = next_tick;
87
88 /* Go do system house keeping. */
89 if (IS_ENABLED(CONFIG_SMP) && (cpu != time_keeper_id))
90 ticks_elapsed = 0;
91 legacy_timer_tick(ticks_elapsed);
92
93 /* Skip clockticks on purpose if we know we would miss those.
94 * The new CR16 must be "later" than current CR16 otherwise
95 * itimer would not fire until CR16 wrapped - e.g 4 seconds
96 * later on a 1Ghz processor. We'll account for the missed
97 * ticks on the next timer interrupt.
98 * We want IT to fire modulo clocktick even if we miss/skip some.
99 * But those interrupts don't in fact get delivered that regularly.
100 *
101 * "next_tick - now" will always give the difference regardless
102 * if one or the other wrapped. If "now" is "bigger" we'll end up
103 * with a very large unsigned number.
104 */
105 now = mfctl(16);
106 while (next_tick - now > cpt)
107 next_tick += cpt;
108
109 /* Program the IT when to deliver the next interrupt.
110 * Only bottom 32-bits of next_tick are writable in CR16!
111 * Timer interrupt will be delivered at least a few hundred cycles
112 * after the IT fires, so if we are too close (<= 8000 cycles) to the
113 * next cycle, simply skip it.
114 */
115 if (next_tick - now <= 8000)
116 next_tick += cpt;
117 mtctl(next_tick, 16);
118
119 return IRQ_HANDLED;
120}
121
122
123unsigned long profile_pc(struct pt_regs *regs)
124{
125 unsigned long pc = instruction_pointer(regs);
126
127 if (regs->gr[0] & PSW_N)
128 pc -= 4;
129
130#ifdef CONFIG_SMP
131 if (in_lock_functions(pc))
132 pc = regs->gr[2];
133#endif
134
135 return pc;
136}
137EXPORT_SYMBOL(profile_pc);
138
139
140/* clock source code */
141
142static u64 notrace read_cr16(struct clocksource *cs)
143{
144 return get_cycles();
145}
146
147static struct clocksource clocksource_cr16 = {
148 .name = "cr16",
149 .rating = 300,
150 .read = read_cr16,
151 .mask = CLOCKSOURCE_MASK(BITS_PER_LONG),
152 .flags = CLOCK_SOURCE_IS_CONTINUOUS,
153};
154
155void start_cpu_itimer(void)
156{
157 unsigned int cpu = smp_processor_id();
158 unsigned long next_tick = mfctl(16) + clocktick;
159
160 mtctl(next_tick, 16); /* kick off Interval Timer (CR16) */
161
162 per_cpu(cpu_data, cpu).it_value = next_tick;
163}
164
165#if IS_ENABLED(CONFIG_RTC_DRV_GENERIC)
166static int rtc_generic_get_time(struct device *dev, struct rtc_time *tm)
167{
168 struct pdc_tod tod_data;
169
170 memset(tm, 0, sizeof(*tm));
171 if (pdc_tod_read(&tod_data) < 0)
172 return -EOPNOTSUPP;
173
174 /* we treat tod_sec as unsigned, so this can work until year 2106 */
175 rtc_time64_to_tm(tod_data.tod_sec, tm);
176 return 0;
177}
178
179static int rtc_generic_set_time(struct device *dev, struct rtc_time *tm)
180{
181 time64_t secs = rtc_tm_to_time64(tm);
182 int ret;
183
184 /* hppa has Y2K38 problem: pdc_tod_set() takes an u32 value! */
185 ret = pdc_tod_set(secs, 0);
186 if (ret != 0) {
187 pr_warn("pdc_tod_set(%lld) returned error %d\n", secs, ret);
188 if (ret == PDC_INVALID_ARG)
189 return -EINVAL;
190 return -EOPNOTSUPP;
191 }
192
193 return 0;
194}
195
196static const struct rtc_class_ops rtc_generic_ops = {
197 .read_time = rtc_generic_get_time,
198 .set_time = rtc_generic_set_time,
199};
200
201static int __init rtc_init(void)
202{
203 struct platform_device *pdev;
204
205 pdev = platform_device_register_data(NULL, "rtc-generic", -1,
206 &rtc_generic_ops,
207 sizeof(rtc_generic_ops));
208
209 return PTR_ERR_OR_ZERO(pdev);
210}
211device_initcall(rtc_init);
212#endif
213
214void read_persistent_clock64(struct timespec64 *ts)
215{
216 static struct pdc_tod tod_data;
217 if (pdc_tod_read(&tod_data) == 0) {
218 ts->tv_sec = tod_data.tod_sec;
219 ts->tv_nsec = tod_data.tod_usec * 1000;
220 } else {
221 printk(KERN_ERR "Error reading tod clock\n");
222 ts->tv_sec = 0;
223 ts->tv_nsec = 0;
224 }
225}
226
227
228static u64 notrace read_cr16_sched_clock(void)
229{
230 return get_cycles();
231}
232
233
234/*
235 * timer interrupt and sched_clock() initialization
236 */
237
238void __init time_init(void)
239{
240 unsigned long cr16_hz;
241
242 clocktick = (100 * PAGE0->mem_10msec) / HZ;
243 start_cpu_itimer(); /* get CPU 0 started */
244
245 cr16_hz = 100 * PAGE0->mem_10msec; /* Hz */
246
247 /* register as sched_clock source */
248 sched_clock_register(read_cr16_sched_clock, BITS_PER_LONG, cr16_hz);
249}
250
251static int __init init_cr16_clocksource(void)
252{
253 /*
254 * The cr16 interval timers are not synchronized across CPUs.
255 */
256 if (num_online_cpus() > 1 && !running_on_qemu) {
257 clocksource_cr16.name = "cr16_unstable";
258 clocksource_cr16.flags = CLOCK_SOURCE_UNSTABLE;
259 clocksource_cr16.rating = 0;
260 }
261
262 /* register at clocksource framework */
263 clocksource_register_hz(&clocksource_cr16,
264 100 * PAGE0->mem_10msec);
265
266 return 0;
267}
268
269device_initcall(init_cr16_clocksource);