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include/asm-i386/mc146818rtc.h
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1da177e4c
Linux-2.6.12-rc2
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/*
* Machine dependent access functions for RTC registers.
*/
#ifndef _ASM_MC146818RTC_H
#define _ASM_MC146818RTC_H
#include <asm/io.h>
#include <asm/system.h>
#include <linux/mc146818rtc.h>
#ifndef RTC_PORT
#define RTC_PORT(x) (0x70 + (x))
#define RTC_ALWAYS_BCD 1 /* RTC operates in binary mode */
#endif
#ifdef __HAVE_ARCH_CMPXCHG
/*
* This lock provides nmi access to the CMOS/RTC registers. It has some
* special properties. It is owned by a CPU and stores the index register
* currently being accessed (if owned). The idea here is that it works
* like a normal lock (normally). However, in an NMI, the NMI code will
* first check to see if its CPU owns the lock, meaning that the NMI
* interrupted during the read/write of the device. If it does, it goes ahead
* and performs the access and then restores the index register. If it does
* not, it locks normally.
*
* Note that since we are working with NMIs, we need this lock even in
* a non-SMP machine just to mark that the lock is owned.
*
* This only works with compare-and-swap. There is no other way to
* atomically claim the lock and set the owner.
*/
#include <linux/smp.h>
extern volatile unsigned long cmos_lock;
/*
* All of these below must be called with interrupts off, preempt
* disabled, etc.
*/
static inline void lock_cmos(unsigned char reg)
{
unsigned long new;
new = ((smp_processor_id()+1) << 8) | reg;
for (;;) {
if (cmos_lock)
continue;
if (__cmpxchg(&cmos_lock, 0, new, sizeof(cmos_lock)) == 0)
return;
}
}
static inline void unlock_cmos(void)
{
cmos_lock = 0;
}
static inline int do_i_have_lock_cmos(void)
{
return (cmos_lock >> 8) == (smp_processor_id()+1);
}
static inline unsigned char current_lock_cmos_reg(void)
{
return cmos_lock & 0xff;
}
#define lock_cmos_prefix(reg) \
do { \
unsigned long cmos_flags; \
local_irq_save(cmos_flags); \
lock_cmos(reg)
#define lock_cmos_suffix(reg) \
unlock_cmos(); \
local_irq_restore(cmos_flags); \
} while (0)
#else
#define lock_cmos_prefix(reg) do {} while (0)
#define lock_cmos_suffix(reg) do {} while (0)
#define lock_cmos(reg)
#define unlock_cmos()
#define do_i_have_lock_cmos() 0
#define current_lock_cmos_reg() 0
#endif
/*
* The yet supported machines all access the RTC index register via
* an ISA port access but the way to access the date register differs ...
*/
#define CMOS_READ(addr) rtc_cmos_read(addr)
#define CMOS_WRITE(val, addr) rtc_cmos_write(val, addr)
unsigned char rtc_cmos_read(unsigned char addr);
void rtc_cmos_write(unsigned char val, unsigned char addr);
#define RTC_IRQ 8
#endif /* _ASM_MC146818RTC_H */
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