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Thomas Gleixner6ce60b02008-01-30 13:30:26 +01001/*
2 * Machine dependent access functions for RTC registers.
3 */
H. Peter Anvin1965aae2008-10-22 22:26:29 -07004#ifndef _ASM_X86_MC146818RTC_H
5#define _ASM_X86_MC146818RTC_H
Thomas Gleixner6ce60b02008-01-30 13:30:26 +01006
7#include <asm/io.h>
8#include <asm/system.h>
9#include <asm/processor.h>
10#include <linux/mc146818rtc.h>
11
12#ifndef RTC_PORT
13#define RTC_PORT(x) (0x70 + (x))
14#define RTC_ALWAYS_BCD 1 /* RTC operates in binary mode */
Thomas Gleixner96a388d2007-10-11 11:20:03 +020015#endif
Thomas Gleixner6ce60b02008-01-30 13:30:26 +010016
17#if defined(CONFIG_X86_32) && defined(__HAVE_ARCH_CMPXCHG)
18/*
19 * This lock provides nmi access to the CMOS/RTC registers. It has some
20 * special properties. It is owned by a CPU and stores the index register
21 * currently being accessed (if owned). The idea here is that it works
22 * like a normal lock (normally). However, in an NMI, the NMI code will
23 * first check to see if its CPU owns the lock, meaning that the NMI
24 * interrupted during the read/write of the device. If it does, it goes ahead
25 * and performs the access and then restores the index register. If it does
26 * not, it locks normally.
27 *
28 * Note that since we are working with NMIs, we need this lock even in
29 * a non-SMP machine just to mark that the lock is owned.
30 *
31 * This only works with compare-and-swap. There is no other way to
32 * atomically claim the lock and set the owner.
33 */
34#include <linux/smp.h>
35extern volatile unsigned long cmos_lock;
36
37/*
38 * All of these below must be called with interrupts off, preempt
39 * disabled, etc.
40 */
41
42static inline void lock_cmos(unsigned char reg)
43{
44 unsigned long new;
Joe Perches933a4412008-03-23 01:02:40 -070045 new = ((smp_processor_id() + 1) << 8) | reg;
Thomas Gleixner6ce60b02008-01-30 13:30:26 +010046 for (;;) {
47 if (cmos_lock) {
48 cpu_relax();
49 continue;
50 }
51 if (__cmpxchg(&cmos_lock, 0, new, sizeof(cmos_lock)) == 0)
52 return;
53 }
54}
55
56static inline void unlock_cmos(void)
57{
58 cmos_lock = 0;
59}
Joe Perches933a4412008-03-23 01:02:40 -070060
Thomas Gleixner6ce60b02008-01-30 13:30:26 +010061static inline int do_i_have_lock_cmos(void)
62{
Joe Perches933a4412008-03-23 01:02:40 -070063 return (cmos_lock >> 8) == (smp_processor_id() + 1);
Thomas Gleixner6ce60b02008-01-30 13:30:26 +010064}
Joe Perches933a4412008-03-23 01:02:40 -070065
Thomas Gleixner6ce60b02008-01-30 13:30:26 +010066static inline unsigned char current_lock_cmos_reg(void)
67{
68 return cmos_lock & 0xff;
69}
Joe Perches933a4412008-03-23 01:02:40 -070070
71#define lock_cmos_prefix(reg) \
Thomas Gleixner6ce60b02008-01-30 13:30:26 +010072 do { \
73 unsigned long cmos_flags; \
74 local_irq_save(cmos_flags); \
75 lock_cmos(reg)
Joe Perches933a4412008-03-23 01:02:40 -070076
77#define lock_cmos_suffix(reg) \
78 unlock_cmos(); \
79 local_irq_restore(cmos_flags); \
Thomas Gleixner6ce60b02008-01-30 13:30:26 +010080 } while (0)
81#else
82#define lock_cmos_prefix(reg) do {} while (0)
83#define lock_cmos_suffix(reg) do {} while (0)
Jesper Juhl1affc462011-12-18 01:05:31 +010084#define lock_cmos(reg) do { } while (0)
85#define unlock_cmos() do { } while (0)
Thomas Gleixner6ce60b02008-01-30 13:30:26 +010086#define do_i_have_lock_cmos() 0
87#define current_lock_cmos_reg() 0
88#endif
89
90/*
91 * The yet supported machines all access the RTC index register via
92 * an ISA port access but the way to access the date register differs ...
93 */
94#define CMOS_READ(addr) rtc_cmos_read(addr)
95#define CMOS_WRITE(val, addr) rtc_cmos_write(val, addr)
96unsigned char rtc_cmos_read(unsigned char addr);
97void rtc_cmos_write(unsigned char val, unsigned char addr);
98
Thomas Gleixnerfe599f92008-01-30 13:30:26 +010099extern int mach_set_rtc_mmss(unsigned long nowtime);
100extern unsigned long mach_get_cmos_time(void);
101
Thomas Gleixner6ce60b02008-01-30 13:30:26 +0100102#define RTC_IRQ 8
103
H. Peter Anvin1965aae2008-10-22 22:26:29 -0700104#endif /* _ASM_X86_MC146818RTC_H */