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