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 <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 */ 15 #endif 16 17 #ifdef __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> 35 extern volatile unsigned long cmos_lock; 36 37 /* 38 * All of these below must be called with interrupts off, preempt 39 * disabled, etc. 40 */ 41 42 static inline void lock_cmos(unsigned char reg) 43 { 44 unsigned long new; 45 new = ((smp_processor_id()+1) << 8) | reg; 46 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 56 static inline void unlock_cmos(void) 57 { 58 cmos_lock = 0; 59 } 60 static inline int do_i_have_lock_cmos(void) 61 { 62 return (cmos_lock >> 8) == (smp_processor_id()+1); 63 } 64 static inline unsigned char current_lock_cmos_reg(void) 65 { 66 return cmos_lock & 0xff; 67 } 68 #define lock_cmos_prefix(reg) \ 69 do { \ 70 unsigned long cmos_flags; \ 71 local_irq_save(cmos_flags); \ 72 lock_cmos(reg) 73 #define lock_cmos_suffix(reg) \ 74 unlock_cmos(); \ 75 local_irq_restore(cmos_flags); \ 76 } while (0) 77 #else 78 #define lock_cmos_prefix(reg) do {} while (0) 79 #define lock_cmos_suffix(reg) do {} while (0) 80 #define lock_cmos(reg) 81 #define unlock_cmos() 82 #define do_i_have_lock_cmos() 0 83 #define current_lock_cmos_reg() 0 84 #endif 85 86 /* 87 * The yet supported machines all access the RTC index register via 88 * an ISA port access but the way to access the date register differs ... 89 */ 90 #define CMOS_READ(addr) rtc_cmos_read(addr) 91 #define CMOS_WRITE(val, addr) rtc_cmos_write(val, addr) 92 unsigned char rtc_cmos_read(unsigned char addr); 93 void rtc_cmos_write(unsigned char val, unsigned char addr); 94 95 #define RTC_IRQ 8 96 97 #endif /* _ASM_MC146818RTC_H */ 98
