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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Precise Delay Loops for S390
4 *
5 * Copyright IBM Corp. 1999, 2008
6 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
7 * Heiko Carstens <heiko.carstens@de.ibm.com>,
8 */
9
10#include <linux/sched.h>
11#include <linux/delay.h>
12#include <linux/timex.h>
13#include <linux/export.h>
14#include <linux/irqflags.h>
15#include <linux/interrupt.h>
16#include <linux/irq.h>
17#include <asm/vtimer.h>
18#include <asm/div64.h>
19#include <asm/idle.h>
20
21void __delay(unsigned long loops)
22{
23 /*
24 * To end the bloody studid and useless discussion about the
25 * BogoMips number I took the liberty to define the __delay
26 * function in a way that that resulting BogoMips number will
27 * yield the megahertz number of the cpu. The important function
28 * is udelay and that is done using the tod clock. -- martin.
29 */
30 asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
31}
32EXPORT_SYMBOL(__delay);
33
34static void __udelay_disabled(unsigned long long usecs)
35{
36 unsigned long cr0, cr0_new, psw_mask;
37 struct s390_idle_data idle;
38 u64 end;
39
40 end = get_tod_clock() + (usecs << 12);
41 __ctl_store(cr0, 0, 0);
42 cr0_new = cr0 & ~CR0_IRQ_SUBCLASS_MASK;
43 cr0_new |= (1UL << (63 - 52)); /* enable clock comparator irq */
44 __ctl_load(cr0_new, 0, 0);
45 psw_mask = __extract_psw() | PSW_MASK_EXT | PSW_MASK_WAIT;
46 set_clock_comparator(end);
47 set_cpu_flag(CIF_IGNORE_IRQ);
48 psw_idle(&idle, psw_mask);
49 clear_cpu_flag(CIF_IGNORE_IRQ);
50 set_clock_comparator(S390_lowcore.clock_comparator);
51 __ctl_load(cr0, 0, 0);
52}
53
54static void __udelay_enabled(unsigned long long usecs)
55{
56 u64 clock_saved, end;
57
58 end = get_tod_clock_fast() + (usecs << 12);
59 do {
60 clock_saved = 0;
61 if (tod_after(S390_lowcore.clock_comparator, end)) {
62 clock_saved = local_tick_disable();
63 set_clock_comparator(end);
64 }
65 enabled_wait();
66 if (clock_saved)
67 local_tick_enable(clock_saved);
68 } while (get_tod_clock_fast() < end);
69}
70
71/*
72 * Waits for 'usecs' microseconds using the TOD clock comparator.
73 */
74void __udelay(unsigned long long usecs)
75{
76 unsigned long flags;
77
78 preempt_disable();
79 local_irq_save(flags);
80 if (in_irq()) {
81 __udelay_disabled(usecs);
82 goto out;
83 }
84 if (in_softirq()) {
85 if (raw_irqs_disabled_flags(flags))
86 __udelay_disabled(usecs);
87 else
88 __udelay_enabled(usecs);
89 goto out;
90 }
91 if (raw_irqs_disabled_flags(flags)) {
92 local_bh_disable();
93 __udelay_disabled(usecs);
94 _local_bh_enable();
95 goto out;
96 }
97 __udelay_enabled(usecs);
98out:
99 local_irq_restore(flags);
100 preempt_enable();
101}
102EXPORT_SYMBOL(__udelay);
103
104/*
105 * Simple udelay variant. To be used on startup and reboot
106 * when the interrupt handler isn't working.
107 */
108void udelay_simple(unsigned long long usecs)
109{
110 u64 end;
111
112 end = get_tod_clock_fast() + (usecs << 12);
113 while (get_tod_clock_fast() < end)
114 cpu_relax();
115}
116
117void __ndelay(unsigned long long nsecs)
118{
119 u64 end;
120
121 nsecs <<= 9;
122 do_div(nsecs, 125);
123 end = get_tod_clock_fast() + nsecs;
124 if (nsecs & ~0xfffUL)
125 __udelay(nsecs >> 12);
126 while (get_tod_clock_fast() < end)
127 barrier();
128}
129EXPORT_SYMBOL(__ndelay);
1/*
2 * Precise Delay Loops for S390
3 *
4 * Copyright IBM Corp. 1999,2008
5 * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>,
6 * Heiko Carstens <heiko.carstens@de.ibm.com>,
7 */
8
9#include <linux/sched.h>
10#include <linux/delay.h>
11#include <linux/timex.h>
12#include <linux/module.h>
13#include <linux/irqflags.h>
14#include <linux/interrupt.h>
15#include <asm/div64.h>
16
17void __delay(unsigned long loops)
18{
19 /*
20 * To end the bloody studid and useless discussion about the
21 * BogoMips number I took the liberty to define the __delay
22 * function in a way that that resulting BogoMips number will
23 * yield the megahertz number of the cpu. The important function
24 * is udelay and that is done using the tod clock. -- martin.
25 */
26 asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1));
27}
28
29static void __udelay_disabled(unsigned long long usecs)
30{
31 unsigned long mask, cr0, cr0_saved;
32 u64 clock_saved;
33 u64 end;
34
35 mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT;
36 end = get_clock() + (usecs << 12);
37 clock_saved = local_tick_disable();
38 __ctl_store(cr0_saved, 0, 0);
39 cr0 = (cr0_saved & 0xffff00e0) | 0x00000800;
40 __ctl_load(cr0 , 0, 0);
41 lockdep_off();
42 do {
43 set_clock_comparator(end);
44 trace_hardirqs_on();
45 __load_psw_mask(mask);
46 local_irq_disable();
47 } while (get_clock() < end);
48 lockdep_on();
49 __ctl_load(cr0_saved, 0, 0);
50 local_tick_enable(clock_saved);
51}
52
53static void __udelay_enabled(unsigned long long usecs)
54{
55 unsigned long mask;
56 u64 clock_saved;
57 u64 end;
58
59 mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT | PSW_MASK_IO;
60 end = get_clock() + (usecs << 12);
61 do {
62 clock_saved = 0;
63 if (end < S390_lowcore.clock_comparator) {
64 clock_saved = local_tick_disable();
65 set_clock_comparator(end);
66 }
67 trace_hardirqs_on();
68 __load_psw_mask(mask);
69 local_irq_disable();
70 if (clock_saved)
71 local_tick_enable(clock_saved);
72 } while (get_clock() < end);
73}
74
75/*
76 * Waits for 'usecs' microseconds using the TOD clock comparator.
77 */
78void __udelay(unsigned long long usecs)
79{
80 unsigned long flags;
81
82 preempt_disable();
83 local_irq_save(flags);
84 if (in_irq()) {
85 __udelay_disabled(usecs);
86 goto out;
87 }
88 if (in_softirq()) {
89 if (raw_irqs_disabled_flags(flags))
90 __udelay_disabled(usecs);
91 else
92 __udelay_enabled(usecs);
93 goto out;
94 }
95 if (raw_irqs_disabled_flags(flags)) {
96 local_bh_disable();
97 __udelay_disabled(usecs);
98 _local_bh_enable();
99 goto out;
100 }
101 __udelay_enabled(usecs);
102out:
103 local_irq_restore(flags);
104 preempt_enable();
105}
106EXPORT_SYMBOL(__udelay);
107
108/*
109 * Simple udelay variant. To be used on startup and reboot
110 * when the interrupt handler isn't working.
111 */
112void udelay_simple(unsigned long long usecs)
113{
114 u64 end;
115
116 end = get_clock() + (usecs << 12);
117 while (get_clock() < end)
118 cpu_relax();
119}
120
121void __ndelay(unsigned long long nsecs)
122{
123 u64 end;
124
125 nsecs <<= 9;
126 do_div(nsecs, 125);
127 end = get_clock() + nsecs;
128 if (nsecs & ~0xfffUL)
129 __udelay(nsecs >> 12);
130 while (get_clock() < end)
131 barrier();
132}
133EXPORT_SYMBOL(__ndelay);