Commit | Line | Data |
---|---|---|
1da177e4 | 1 | /* |
1da177e4 LT |
2 | * Precise Delay Loops for S390 |
3 | * | |
d3d238c7 HC |
4 | * Copyright IBM Corp. 1999,2008 |
5 | * Author(s): Martin Schwidefsky <schwidefsky@de.ibm.com>, | |
6 | * Heiko Carstens <heiko.carstens@de.ibm.com>, | |
1da177e4 LT |
7 | */ |
8 | ||
1da177e4 LT |
9 | #include <linux/sched.h> |
10 | #include <linux/delay.h> | |
d54853ef MS |
11 | #include <linux/timex.h> |
12 | #include <linux/irqflags.h> | |
bf6f6aa4 | 13 | #include <linux/interrupt.h> |
1da177e4 LT |
14 | |
15 | void __delay(unsigned long loops) | |
16 | { | |
17 | /* | |
18 | * To end the bloody studid and useless discussion about the | |
19 | * BogoMips number I took the liberty to define the __delay | |
20 | * function in a way that that resulting BogoMips number will | |
21 | * yield the megahertz number of the cpu. The important function | |
22 | * is udelay and that is done using the tod clock. -- martin. | |
23 | */ | |
94c12cc7 | 24 | asm volatile("0: brct %0,0b" : : "d" ((loops/2) + 1)); |
1da177e4 LT |
25 | } |
26 | ||
d3d238c7 | 27 | static void __udelay_disabled(unsigned long usecs) |
1da177e4 | 28 | { |
d3d238c7 HC |
29 | unsigned long mask, cr0, cr0_saved; |
30 | u64 clock_saved; | |
d54853ef | 31 | |
d3d238c7 HC |
32 | clock_saved = local_tick_disable(); |
33 | set_clock_comparator(get_clock() + ((u64) usecs << 12)); | |
34 | __ctl_store(cr0_saved, 0, 0); | |
35 | cr0 = (cr0_saved & 0xffff00e0) | 0x00000800; | |
36 | __ctl_load(cr0 , 0, 0); | |
37 | mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT; | |
38 | trace_hardirqs_on(); | |
39 | __load_psw_mask(mask); | |
40 | local_irq_disable(); | |
41 | __ctl_load(cr0_saved, 0, 0); | |
42 | local_tick_enable(clock_saved); | |
43 | set_clock_comparator(S390_lowcore.clock_comparator); | |
44 | } | |
d54853ef | 45 | |
d3d238c7 HC |
46 | static void __udelay_enabled(unsigned long usecs) |
47 | { | |
48 | unsigned long mask; | |
49 | u64 end, time; | |
50 | ||
51 | mask = psw_kernel_bits | PSW_MASK_WAIT | PSW_MASK_EXT | PSW_MASK_IO; | |
d54853ef MS |
52 | end = get_clock() + ((u64) usecs << 12); |
53 | do { | |
5a62b192 HC |
54 | time = end < S390_lowcore.clock_comparator ? |
55 | end : S390_lowcore.clock_comparator; | |
d54853ef MS |
56 | set_clock_comparator(time); |
57 | trace_hardirqs_on(); | |
58 | __load_psw_mask(mask); | |
59 | local_irq_disable(); | |
60 | } while (get_clock() < end); | |
d3d238c7 HC |
61 | set_clock_comparator(S390_lowcore.clock_comparator); |
62 | } | |
1da177e4 | 63 | |
d3d238c7 HC |
64 | /* |
65 | * Waits for 'usecs' microseconds using the TOD clock comparator. | |
66 | */ | |
67 | void __udelay(unsigned long usecs) | |
68 | { | |
69 | unsigned long flags; | |
70 | ||
71 | preempt_disable(); | |
72 | local_irq_save(flags); | |
73 | if (in_irq()) { | |
74 | __udelay_disabled(usecs); | |
75 | goto out; | |
76 | } | |
77 | if (in_softirq()) { | |
78 | if (raw_irqs_disabled_flags(flags)) | |
79 | __udelay_disabled(usecs); | |
80 | else | |
81 | __udelay_enabled(usecs); | |
82 | goto out; | |
d54853ef | 83 | } |
d3d238c7 HC |
84 | if (raw_irqs_disabled_flags(flags)) { |
85 | local_bh_disable(); | |
86 | __udelay_disabled(usecs); | |
bf6f6aa4 | 87 | _local_bh_enable(); |
d3d238c7 HC |
88 | goto out; |
89 | } | |
90 | __udelay_enabled(usecs); | |
91 | out: | |
d54853ef | 92 | local_irq_restore(flags); |
d3d238c7 | 93 | preempt_enable(); |
1da177e4 | 94 | } |