1 /* 2 * Machine dependent access functions for RTC registers. 3 */ 4 #ifndef _ASM_X86_MC146818RTC_H 5 #define _ASM_X86_MC146818RTC_H 6 7 #include <asm/io.h> 8 #include <asm/processor.h> 9 10 #ifndef RTC_PORT 11 #define RTC_PORT(x) (0x70 + (x)) 12 #define RTC_ALWAYS_BCD 1 /* RTC operates in binary mode */ 13 #endif 14 15 #if defined(CONFIG_X86_32) 16 /* 17 * This lock provides nmi access to the CMOS/RTC registers. It has some 18 * special properties. It is owned by a CPU and stores the index register 19 * currently being accessed (if owned). The idea here is that it works 20 * like a normal lock (normally). However, in an NMI, the NMI code will 21 * first check to see if its CPU owns the lock, meaning that the NMI 22 * interrupted during the read/write of the device. If it does, it goes ahead 23 * and performs the access and then restores the index register. If it does 24 * not, it locks normally. 25 * 26 * Note that since we are working with NMIs, we need this lock even in 27 * a non-SMP machine just to mark that the lock is owned. 28 * 29 * This only works with compare-and-swap. There is no other way to 30 * atomically claim the lock and set the owner. 31 */ 32 #include <linux/smp.h> 33 extern volatile unsigned long cmos_lock; 34 35 /* 36 * All of these below must be called with interrupts off, preempt 37 * disabled, etc. 38 */ 39 40 static inline void lock_cmos(unsigned char reg) 41 { 42 unsigned long new; 43 new = ((smp_processor_id() + 1) << 8) | reg; 44 for (;;) { 45 if (cmos_lock) { 46 cpu_relax(); 47 continue; 48 } 49 if (__cmpxchg(&cmos_lock, 0, new, sizeof(cmos_lock)) == 0) 50 return; 51 } 52 } 53 54 static inline void unlock_cmos(void) 55 { 56 cmos_lock = 0; 57 } 58 59 static inline int do_i_have_lock_cmos(void) 60 { 61 return (cmos_lock >> 8) == (smp_processor_id() + 1); 62 } 63 64 static inline unsigned char current_lock_cmos_reg(void) 65 { 66 return cmos_lock & 0xff; 67 } 68 69 #define lock_cmos_prefix(reg) \ 70 do { \ 71 unsigned long cmos_flags; \ 72 local_irq_save(cmos_flags); \ 73 lock_cmos(reg) 74 75 #define lock_cmos_suffix(reg) \ 76 unlock_cmos(); \ 77 local_irq_restore(cmos_flags); \ 78 } while (0) 79 #else 80 #define lock_cmos_prefix(reg) do {} while (0) 81 #define lock_cmos_suffix(reg) do {} while (0) 82 #define lock_cmos(reg) do { } while (0) 83 #define unlock_cmos() do { } while (0) 84 #define do_i_have_lock_cmos() 0 85 #define current_lock_cmos_reg() 0 86 #endif 87 88 /* 89 * The yet supported machines all access the RTC index register via 90 * an ISA port access but the way to access the date register differs ... 91 */ 92 #define CMOS_READ(addr) rtc_cmos_read(addr) 93 #define CMOS_WRITE(val, addr) rtc_cmos_write(val, addr) 94 unsigned char rtc_cmos_read(unsigned char addr); 95 void rtc_cmos_write(unsigned char val, unsigned char addr); 96 97 extern int mach_set_rtc_mmss(const struct timespec *now); 98 extern void mach_get_cmos_time(struct timespec *now); 99 100 #define RTC_IRQ 8 101 102 #endif /* _ASM_X86_MC146818RTC_H */ 103