1/*
2 * include/asm-arm/arch-ns9xxx/clock.h
3 *
4 * Copyright (C) 2007 by Digi International Inc.
5 * All rights reserved.
6 *
7 * This program is free software; you can redistribute it and/or modify it
8 * under the terms of the GNU General Public License version 2 as published by
9 * the Free Software Foundation.
10 */
11#ifndef __ASM_ARCH_CLOCK_H
12#define __ASM_ARCH_CLOCK_H
13
14#include <asm/arch-ns9xxx/regs-sys.h>
15
16#define CRYSTAL 29491200 /* Hz */
17
18/* The HRM calls this value f_vco */
19static inline u32 ns9xxx_systemclock(void) __attribute__((const));
20static inline u32 ns9xxx_systemclock(void)
21{
22	u32 pll = SYS_PLL;
23
24	/*
25	 * The system clock should be a multiple of HZ * TIMERCLOCKSELECT (in
26	 * time.c).
27	 *
28	 * The following values are given:
29	 *   - TIMERCLOCKSELECT == 2^i for an i in {0 .. 6}
30	 *   - CRYSTAL == 29491200 == 2^17 * 3^2 * 5^2
31	 *   - ND in {0 .. 31}
32	 *   - FS in {0 .. 3}
33	 *
34	 * Assuming the worst, we consider:
35	 *   - TIMERCLOCKSELECT == 64
36	 *   - ND == 0
37	 *   - FS == 3
38	 *
39	 * So HZ should be a divisor of:
40	 *      (CRYSTAL * (ND + 1) >> FS) / TIMERCLOCKSELECT
41	 *   == (2^17 * 3^2 * 5^2 * 1 >> 3) / 64
42	 *   == 2^8 * 3^2 * 5^2
43	 *   == 57600
44	 *
45	 * Currently HZ is defined to be 100 for this platform.
46	 *
47	 * Fine.
48	 */
49	return CRYSTAL * (REGGET(pll, SYS_PLL, ND) + 1)
50		>> REGGET(pll, SYS_PLL, FS);
51}
52
53static inline u32 ns9xxx_cpuclock(void) __attribute__((const));
54static inline u32 ns9xxx_cpuclock(void)
55{
56	return ns9xxx_systemclock() / 2;
57}
58
59static inline u32 ns9xxx_ahbclock(void) __attribute__((const));
60static inline u32 ns9xxx_ahbclock(void)
61{
62	return ns9xxx_systemclock() / 4;
63}
64
65static inline u32 ns9xxx_bbusclock(void) __attribute__((const));
66static inline u32 ns9xxx_bbusclock(void)
67{
68	return ns9xxx_systemclock() / 8;
69}
70
71#endif /* ifndef __ASM_ARCH_CLOCK_H */
72