1/*  linux/include/linux/clocksource.h
2 *
3 *  This file contains the structure definitions for clocksources.
4 *
5 *  If you are not a clocksource, or timekeeping code, you should
6 *  not be including this file!
7 */
8#ifndef _LINUX_CLOCKSOURCE_H
9#define _LINUX_CLOCKSOURCE_H
10
11#include <linux/types.h>
12#include <linux/timex.h>
13#include <linux/time.h>
14#include <linux/list.h>
15#include <linux/cache.h>
16#include <linux/timer.h>
17#include <linux/init.h>
18#include <asm/div64.h>
19#include <asm/io.h>
20
21struct clocksource;
22struct module;
23
24#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
25#include <asm/clocksource.h>
26#endif
27
28/**
29 * struct clocksource - hardware abstraction for a free running counter
30 *	Provides mostly state-free accessors to the underlying hardware.
31 *	This is the structure used for system time.
32 *
33 * @name:		ptr to clocksource name
34 * @list:		list head for registration
35 * @rating:		rating value for selection (higher is better)
36 *			To avoid rating inflation the following
37 *			list should give you a guide as to how
38 *			to assign your clocksource a rating
39 *			1-99: Unfit for real use
40 *				Only available for bootup and testing purposes.
41 *			100-199: Base level usability.
42 *				Functional for real use, but not desired.
43 *			200-299: Good.
44 *				A correct and usable clocksource.
45 *			300-399: Desired.
46 *				A reasonably fast and accurate clocksource.
47 *			400-499: Perfect
48 *				The ideal clocksource. A must-use where
49 *				available.
50 * @read:		returns a cycle value, passes clocksource as argument
51 * @enable:		optional function to enable the clocksource
52 * @disable:		optional function to disable the clocksource
53 * @mask:		bitmask for two's complement
54 *			subtraction of non 64 bit counters
55 * @mult:		cycle to nanosecond multiplier
56 * @shift:		cycle to nanosecond divisor (power of two)
57 * @max_idle_ns:	max idle time permitted by the clocksource (nsecs)
58 * @maxadj:		maximum adjustment value to mult (~11%)
59 * @max_cycles:		maximum safe cycle value which won't overflow on multiplication
60 * @flags:		flags describing special properties
61 * @archdata:		arch-specific data
62 * @suspend:		suspend function for the clocksource, if necessary
63 * @resume:		resume function for the clocksource, if necessary
64 * @owner:		module reference, must be set by clocksource in modules
65 */
66struct clocksource {
67	/*
68	 * Hotpath data, fits in a single cache line when the
69	 * clocksource itself is cacheline aligned.
70	 */
71	cycle_t (*read)(struct clocksource *cs);
72	cycle_t mask;
73	u32 mult;
74	u32 shift;
75	u64 max_idle_ns;
76	u32 maxadj;
77#ifdef CONFIG_ARCH_CLOCKSOURCE_DATA
78	struct arch_clocksource_data archdata;
79#endif
80	u64 max_cycles;
81	const char *name;
82	struct list_head list;
83	int rating;
84	int (*enable)(struct clocksource *cs);
85	void (*disable)(struct clocksource *cs);
86	unsigned long flags;
87	void (*suspend)(struct clocksource *cs);
88	void (*resume)(struct clocksource *cs);
89
90	/* private: */
91#ifdef CONFIG_CLOCKSOURCE_WATCHDOG
92	/* Watchdog related data, used by the framework */
93	struct list_head wd_list;
94	cycle_t cs_last;
95	cycle_t wd_last;
96#endif
97	struct module *owner;
98} ____cacheline_aligned;
99
100/*
101 * Clock source flags bits::
102 */
103#define CLOCK_SOURCE_IS_CONTINUOUS		0x01
104#define CLOCK_SOURCE_MUST_VERIFY		0x02
105
106#define CLOCK_SOURCE_WATCHDOG			0x10
107#define CLOCK_SOURCE_VALID_FOR_HRES		0x20
108#define CLOCK_SOURCE_UNSTABLE			0x40
109#define CLOCK_SOURCE_SUSPEND_NONSTOP		0x80
110#define CLOCK_SOURCE_RESELECT			0x100
111
112/* simplify initialization of mask field */
113#define CLOCKSOURCE_MASK(bits) (cycle_t)((bits) < 64 ? ((1ULL<<(bits))-1) : -1)
114
115/**
116 * clocksource_khz2mult - calculates mult from khz and shift
117 * @khz:		Clocksource frequency in KHz
118 * @shift_constant:	Clocksource shift factor
119 *
120 * Helper functions that converts a khz counter frequency to a timsource
121 * multiplier, given the clocksource shift value
122 */
123static inline u32 clocksource_khz2mult(u32 khz, u32 shift_constant)
124{
125	/*  khz = cyc/(Million ns)
126	 *  mult/2^shift  = ns/cyc
127	 *  mult = ns/cyc * 2^shift
128	 *  mult = 1Million/khz * 2^shift
129	 *  mult = 1000000 * 2^shift / khz
130	 *  mult = (1000000<<shift) / khz
131	 */
132	u64 tmp = ((u64)1000000) << shift_constant;
133
134	tmp += khz/2; /* round for do_div */
135	do_div(tmp, khz);
136
137	return (u32)tmp;
138}
139
140/**
141 * clocksource_hz2mult - calculates mult from hz and shift
142 * @hz:			Clocksource frequency in Hz
143 * @shift_constant:	Clocksource shift factor
144 *
145 * Helper functions that converts a hz counter
146 * frequency to a timsource multiplier, given the
147 * clocksource shift value
148 */
149static inline u32 clocksource_hz2mult(u32 hz, u32 shift_constant)
150{
151	/*  hz = cyc/(Billion ns)
152	 *  mult/2^shift  = ns/cyc
153	 *  mult = ns/cyc * 2^shift
154	 *  mult = 1Billion/hz * 2^shift
155	 *  mult = 1000000000 * 2^shift / hz
156	 *  mult = (1000000000<<shift) / hz
157	 */
158	u64 tmp = ((u64)1000000000) << shift_constant;
159
160	tmp += hz/2; /* round for do_div */
161	do_div(tmp, hz);
162
163	return (u32)tmp;
164}
165
166/**
167 * clocksource_cyc2ns - converts clocksource cycles to nanoseconds
168 * @cycles:	cycles
169 * @mult:	cycle to nanosecond multiplier
170 * @shift:	cycle to nanosecond divisor (power of two)
171 *
172 * Converts cycles to nanoseconds, using the given mult and shift.
173 *
174 * XXX - This could use some mult_lxl_ll() asm optimization
175 */
176static inline s64 clocksource_cyc2ns(cycle_t cycles, u32 mult, u32 shift)
177{
178	return ((u64) cycles * mult) >> shift;
179}
180
181
182extern int clocksource_unregister(struct clocksource*);
183extern void clocksource_touch_watchdog(void);
184extern struct clocksource* clocksource_get_next(void);
185extern void clocksource_change_rating(struct clocksource *cs, int rating);
186extern void clocksource_suspend(void);
187extern void clocksource_resume(void);
188extern struct clocksource * __init clocksource_default_clock(void);
189extern void clocksource_mark_unstable(struct clocksource *cs);
190
191extern u64
192clocks_calc_max_nsecs(u32 mult, u32 shift, u32 maxadj, u64 mask, u64 *max_cycles);
193extern void
194clocks_calc_mult_shift(u32 *mult, u32 *shift, u32 from, u32 to, u32 minsec);
195
196/*
197 * Don't call __clocksource_register_scale directly, use
198 * clocksource_register_hz/khz
199 */
200extern int
201__clocksource_register_scale(struct clocksource *cs, u32 scale, u32 freq);
202extern void
203__clocksource_update_freq_scale(struct clocksource *cs, u32 scale, u32 freq);
204
205/*
206 * Don't call this unless you are a default clocksource
207 * (AKA: jiffies) and absolutely have to.
208 */
209static inline int __clocksource_register(struct clocksource *cs)
210{
211	return __clocksource_register_scale(cs, 1, 0);
212}
213
214static inline int clocksource_register_hz(struct clocksource *cs, u32 hz)
215{
216	return __clocksource_register_scale(cs, 1, hz);
217}
218
219static inline int clocksource_register_khz(struct clocksource *cs, u32 khz)
220{
221	return __clocksource_register_scale(cs, 1000, khz);
222}
223
224static inline void __clocksource_update_freq_hz(struct clocksource *cs, u32 hz)
225{
226	__clocksource_update_freq_scale(cs, 1, hz);
227}
228
229static inline void __clocksource_update_freq_khz(struct clocksource *cs, u32 khz)
230{
231	__clocksource_update_freq_scale(cs, 1000, khz);
232}
233
234
235extern int timekeeping_notify(struct clocksource *clock);
236
237extern cycle_t clocksource_mmio_readl_up(struct clocksource *);
238extern cycle_t clocksource_mmio_readl_down(struct clocksource *);
239extern cycle_t clocksource_mmio_readw_up(struct clocksource *);
240extern cycle_t clocksource_mmio_readw_down(struct clocksource *);
241
242extern int clocksource_mmio_init(void __iomem *, const char *,
243	unsigned long, int, unsigned, cycle_t (*)(struct clocksource *));
244
245extern int clocksource_i8253_init(void);
246
247#define CLOCKSOURCE_OF_DECLARE(name, compat, fn) \
248	OF_DECLARE_1(clksrc, name, compat, fn)
249
250#ifdef CONFIG_CLKSRC_OF
251extern void clocksource_of_init(void);
252#else
253static inline void clocksource_of_init(void) {}
254#endif
255
256#ifdef CONFIG_ACPI
257void acpi_generic_timer_init(void);
258#else
259static inline void acpi_generic_timer_init(void) { }
260#endif
261
262#endif /* _LINUX_CLOCKSOURCE_H */
263