blob: 01fdf5674e24da868a04c717a7792be302717483 [file] [log] [blame]
* Machine dependent access functions for RTC registers.
#ifndef _ASM_X86_MC146818RTC_H
#define _ASM_X86_MC146818RTC_H
#include <asm/io.h>
#include <asm/system.h>
#include <asm/processor.h>
#include <linux/mc146818rtc.h>
#ifndef RTC_PORT
#define RTC_PORT(x) (0x70 + (x))
#define RTC_ALWAYS_BCD 1 /* RTC operates in binary mode */
#if defined(CONFIG_X86_32) && defined(__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) {
if (__cmpxchg(&cmos_lock, 0, new, sizeof(cmos_lock)) == 0)
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); \
#define lock_cmos_suffix(reg) \
unlock_cmos(); \
local_irq_restore(cmos_flags); \
} while (0)
#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
* 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);
extern int mach_set_rtc_mmss(unsigned long nowtime);
extern unsigned long mach_get_cmos_time(void);
#define RTC_IRQ 8
#endif /* _ASM_X86_MC146818RTC_H */