Thomas Gleixner | 6ce60b0 | 2008-01-30 13:30:26 +0100 | [diff] [blame] | 1 | /* |
| 2 | * Machine dependent access functions for RTC registers. |
| 3 | */ |
H. Peter Anvin | 1965aae | 2008-10-22 22:26:29 -0700 | [diff] [blame^] | 4 | #ifndef _ASM_X86_MC146818RTC_H |
| 5 | #define _ASM_X86_MC146818RTC_H |
Thomas Gleixner | 6ce60b0 | 2008-01-30 13:30:26 +0100 | [diff] [blame] | 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 */ |
Thomas Gleixner | 96a388d | 2007-10-11 11:20:03 +0200 | [diff] [blame] | 15 | #endif |
Thomas Gleixner | 6ce60b0 | 2008-01-30 13:30:26 +0100 | [diff] [blame] | 16 | |
| 17 | #if defined(CONFIG_X86_32) && defined(__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; |
Joe Perches | 933a441 | 2008-03-23 01:02:40 -0700 | [diff] [blame] | 45 | new = ((smp_processor_id() + 1) << 8) | reg; |
Thomas Gleixner | 6ce60b0 | 2008-01-30 13:30:26 +0100 | [diff] [blame] | 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 | } |
Joe Perches | 933a441 | 2008-03-23 01:02:40 -0700 | [diff] [blame] | 60 | |
Thomas Gleixner | 6ce60b0 | 2008-01-30 13:30:26 +0100 | [diff] [blame] | 61 | static inline int do_i_have_lock_cmos(void) |
| 62 | { |
Joe Perches | 933a441 | 2008-03-23 01:02:40 -0700 | [diff] [blame] | 63 | return (cmos_lock >> 8) == (smp_processor_id() + 1); |
Thomas Gleixner | 6ce60b0 | 2008-01-30 13:30:26 +0100 | [diff] [blame] | 64 | } |
Joe Perches | 933a441 | 2008-03-23 01:02:40 -0700 | [diff] [blame] | 65 | |
Thomas Gleixner | 6ce60b0 | 2008-01-30 13:30:26 +0100 | [diff] [blame] | 66 | static inline unsigned char current_lock_cmos_reg(void) |
| 67 | { |
| 68 | return cmos_lock & 0xff; |
| 69 | } |
Joe Perches | 933a441 | 2008-03-23 01:02:40 -0700 | [diff] [blame] | 70 | |
| 71 | #define lock_cmos_prefix(reg) \ |
Thomas Gleixner | 6ce60b0 | 2008-01-30 13:30:26 +0100 | [diff] [blame] | 72 | do { \ |
| 73 | unsigned long cmos_flags; \ |
| 74 | local_irq_save(cmos_flags); \ |
| 75 | lock_cmos(reg) |
Joe Perches | 933a441 | 2008-03-23 01:02:40 -0700 | [diff] [blame] | 76 | |
| 77 | #define lock_cmos_suffix(reg) \ |
| 78 | unlock_cmos(); \ |
| 79 | local_irq_restore(cmos_flags); \ |
Thomas Gleixner | 6ce60b0 | 2008-01-30 13:30:26 +0100 | [diff] [blame] | 80 | } while (0) |
| 81 | #else |
| 82 | #define lock_cmos_prefix(reg) do {} while (0) |
| 83 | #define lock_cmos_suffix(reg) do {} while (0) |
| 84 | #define lock_cmos(reg) |
| 85 | #define unlock_cmos() |
| 86 | #define do_i_have_lock_cmos() 0 |
| 87 | #define current_lock_cmos_reg() 0 |
| 88 | #endif |
| 89 | |
| 90 | /* |
| 91 | * The yet supported machines all access the RTC index register via |
| 92 | * an ISA port access but the way to access the date register differs ... |
| 93 | */ |
| 94 | #define CMOS_READ(addr) rtc_cmos_read(addr) |
| 95 | #define CMOS_WRITE(val, addr) rtc_cmos_write(val, addr) |
| 96 | unsigned char rtc_cmos_read(unsigned char addr); |
| 97 | void rtc_cmos_write(unsigned char val, unsigned char addr); |
| 98 | |
Thomas Gleixner | fe599f9 | 2008-01-30 13:30:26 +0100 | [diff] [blame] | 99 | extern int mach_set_rtc_mmss(unsigned long nowtime); |
| 100 | extern unsigned long mach_get_cmos_time(void); |
| 101 | |
Thomas Gleixner | 6ce60b0 | 2008-01-30 13:30:26 +0100 | [diff] [blame] | 102 | #define RTC_IRQ 8 |
| 103 | |
H. Peter Anvin | 1965aae | 2008-10-22 22:26:29 -0700 | [diff] [blame^] | 104 | #endif /* _ASM_X86_MC146818RTC_H */ |