1/* 2 * Machine dependent access functions for RTC registers. 3 */ 4#ifndef _ASM_MC146818RTC_H 5#define _ASM_MC146818RTC_H 6 7#include <asm/io.h> 8#include <asm/system.h> 9#include <linux/mc146818rtc.h> 10 11#ifndef RTC_PORT 12#define RTC_PORT(x) (0x70 + (x)) 13#define RTC_ALWAYS_BCD 1 /* RTC operates in binary mode */ 14#endif 15 16#ifdef __HAVE_ARCH_CMPXCHG 17/* 18 * This lock provides nmi access to the CMOS/RTC registers. It has some 19 * special properties. It is owned by a CPU and stores the index register 20 * currently being accessed (if owned). The idea here is that it works 21 * like a normal lock (normally). However, in an NMI, the NMI code will 22 * first check to see if its CPU owns the lock, meaning that the NMI 23 * interrupted during the read/write of the device. If it does, it goes ahead 24 * and performs the access and then restores the index register. If it does 25 * not, it locks normally. 26 * 27 * Note that since we are working with NMIs, we need this lock even in 28 * a non-SMP machine just to mark that the lock is owned. 29 * 30 * This only works with compare-and-swap. There is no other way to 31 * atomically claim the lock and set the owner. 32 */ 33#include <linux/smp.h> 34extern volatile unsigned long cmos_lock; 35 36/* 37 * All of these below must be called with interrupts off, preempt 38 * disabled, etc. 39 */ 40 41static inline void lock_cmos(unsigned char reg) 42{ 43 unsigned long new; 44 new = ((smp_processor_id()+1) << 8) | reg; 45 for (;;) { 46 if (cmos_lock) 47 continue; 48 if (__cmpxchg(&cmos_lock, 0, new, sizeof(cmos_lock)) == 0) 49 return; 50 } 51} 52 53static inline void unlock_cmos(void) 54{ 55 cmos_lock = 0; 56} 57static inline int do_i_have_lock_cmos(void) 58{ 59 return (cmos_lock >> 8) == (smp_processor_id()+1); 60} 61static inline unsigned char current_lock_cmos_reg(void) 62{ 63 return cmos_lock & 0xff; 64} 65#define lock_cmos_prefix(reg) \ 66 do { \ 67 unsigned long cmos_flags; \ 68 local_irq_save(cmos_flags); \ 69 lock_cmos(reg) 70#define lock_cmos_suffix(reg) \ 71 unlock_cmos(); \ 72 local_irq_restore(cmos_flags); \ 73 } while (0) 74#else 75#define lock_cmos_prefix(reg) do {} while (0) 76#define lock_cmos_suffix(reg) do {} while (0) 77#define lock_cmos(reg) 78#define unlock_cmos() 79#define do_i_have_lock_cmos() 0 80#define current_lock_cmos_reg() 0 81#endif 82 83/* 84 * The yet supported machines all access the RTC index register via 85 * an ISA port access but the way to access the date register differs ... 86 */ 87#define CMOS_READ(addr) rtc_cmos_read(addr) 88#define CMOS_WRITE(val, addr) rtc_cmos_write(val, addr) 89unsigned char rtc_cmos_read(unsigned char addr); 90void rtc_cmos_write(unsigned char val, unsigned char addr); 91 92#define RTC_IRQ 8 93 94#endif /* _ASM_MC146818RTC_H */ 95