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b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
1da177e4 | 2 | /* |
1da177e4 LT |
3 | * Precise Delay Loops for S390 |
4 | * | |
a53c8fab | 5 | * Copyright IBM Corp. 1999, 2008 |
d3d238c7 HC |
6 | * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>, |
7 | * Heiko Carstens <heiko.carstens@de.ibm.com>, | |
1da177e4 LT |
8 | */ |
9 | ||
1da177e4 LT |
10 | #include <linux/sched.h> |
11 | #include <linux/delay.h> | |
d54853ef | 12 | #include <linux/timex.h> |
d3217967 | 13 | #include <linux/export.h> |
d54853ef | 14 | #include <linux/irqflags.h> |
bf6f6aa4 | 15 | #include <linux/interrupt.h> |
db7e007f | 16 | #include <linux/irq.h> |
27f6b416 | 17 | #include <asm/vtimer.h> |
b3966378 | 18 | #include <asm/div64.h> |
db7e007f | 19 | #include <asm/idle.h> |
1da177e4 LT |
20 | |
21 | void __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 | */ | |
94c12cc7 | 30 | asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1)); |
1da177e4 | 31 | } |
854508c0 | 32 | EXPORT_SYMBOL(__delay); |
1da177e4 | 33 | |
0cd6a403 | 34 | static void __udelay_disabled(unsigned long long usecs) |
1da177e4 | 35 | { |
db7e007f HC |
36 | unsigned long cr0, cr0_new, psw_mask; |
37 | struct s390_idle_data idle; | |
38 | u64 end; | |
d54853ef | 39 | |
1aae0560 | 40 | end = get_tod_clock() + (usecs << 12); |
4c1051e3 | 41 | __ctl_store(cr0, 0, 0); |
db7e007f HC |
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); | |
4c1051e3 | 51 | __ctl_load(cr0, 0, 0); |
d3d238c7 | 52 | } |
d54853ef | 53 | |
0cd6a403 | 54 | static void __udelay_enabled(unsigned long long usecs) |
d3d238c7 | 55 | { |
4c1051e3 | 56 | u64 clock_saved, end; |
d3d238c7 | 57 | |
8c071b0f | 58 | end = get_tod_clock_fast() + (usecs << 12); |
d54853ef | 59 | do { |
78d81f2f | 60 | clock_saved = 0; |
6e2ef5e4 | 61 | if (tod_after(S390_lowcore.clock_comparator, end)) { |
78d81f2f CB |
62 | clock_saved = local_tick_disable(); |
63 | set_clock_comparator(end); | |
64 | } | |
b5f87f15 | 65 | enabled_wait(); |
78d81f2f CB |
66 | if (clock_saved) |
67 | local_tick_enable(clock_saved); | |
8c071b0f | 68 | } while (get_tod_clock_fast() < end); |
d3d238c7 | 69 | } |
1da177e4 | 70 | |
d3d238c7 HC |
71 | /* |
72 | * Waits for 'usecs' microseconds using the TOD clock comparator. | |
73 | */ | |
0cd6a403 | 74 | void __udelay(unsigned long long usecs) |
d3d238c7 HC |
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; | |
d54853ef | 90 | } |
d3d238c7 HC |
91 | if (raw_irqs_disabled_flags(flags)) { |
92 | local_bh_disable(); | |
93 | __udelay_disabled(usecs); | |
bf6f6aa4 | 94 | _local_bh_enable(); |
d3d238c7 HC |
95 | goto out; |
96 | } | |
97 | __udelay_enabled(usecs); | |
98 | out: | |
d54853ef | 99 | local_irq_restore(flags); |
d3d238c7 | 100 | preempt_enable(); |
1da177e4 | 101 | } |
1485c5c8 | 102 | EXPORT_SYMBOL(__udelay); |
5a0d0e65 HC |
103 | |
104 | /* | |
105 | * Simple udelay variant. To be used on startup and reboot | |
106 | * when the interrupt handler isn't working. | |
107 | */ | |
0cd6a403 | 108 | void udelay_simple(unsigned long long usecs) |
5a0d0e65 HC |
109 | { |
110 | u64 end; | |
111 | ||
8c071b0f MS |
112 | end = get_tod_clock_fast() + (usecs << 12); |
113 | while (get_tod_clock_fast() < end) | |
5a0d0e65 HC |
114 | cpu_relax(); |
115 | } | |
b3966378 HC |
116 | |
117 | void __ndelay(unsigned long long nsecs) | |
118 | { | |
119 | u64 end; | |
120 | ||
121 | nsecs <<= 9; | |
122 | do_div(nsecs, 125); | |
8c071b0f | 123 | end = get_tod_clock_fast() + nsecs; |
b3966378 HC |
124 | if (nsecs & ~0xfffUL) |
125 | __udelay(nsecs >> 12); | |
8c071b0f | 126 | while (get_tod_clock_fast() < end) |
b3966378 HC |
127 | barrier(); |
128 | } | |
129 | EXPORT_SYMBOL(__ndelay); |