2 * This file is part of the libpayload project.
4 * Copyright (C) 2008 Advanced Micro Devices, Inc.
6 * Redistribution and use in source and binary forms, with or without
7 * modification, are permitted provided that the following conditions
9 * 1. Redistributions of source code must retain the above copyright
10 * notice, this list of conditions and the following disclaimer.
11 * 2. Redistributions in binary form must reproduce the above copyright
12 * notice, this list of conditions and the following disclaimer in the
13 * documentation and/or other materials provided with the distribution.
14 * 3. The name of the author may not be used to endorse or promote products
15 * derived from this software without specific prior written permission.
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
21 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 #include <libpayload.h>
31 #include <arch/rdtsc.h>
33 static unsigned int cpu_khz;
35 /* Calculate the speed of the processor for use in delays */
37 void get_cpu_speed(void)
39 unsigned long long start, end;
41 /* Set up the PPC port - disable the speaker,
42 * enable the T2 gate */
44 outb((inb(0x61) & ~0x02) | 0x01, 0x61);
46 /* Set the PIT to Mode 0, counter 2, word access */
49 /* Load the counter with 0xFFFF */
54 /* Read the number of ticks during the period */
57 while(!(inb(0x61) & 0x20));
60 /* The clock rate is 1193180 Hz
61 * the number of miliseconds for a period
62 * of 0xFFFF is 1193180 / (0xFFFF * 1000)
63 * or .0182. Multiply that by the number of
64 * measured clocks to get the khz value
68 (unsigned int ) ((end - start) * 1193180U / (1000 * 0xFFFF));
71 /* Global delay functions */
73 static inline void _delay(unsigned int delta)
75 unsigned long long timeout = rdtsc() + delta;
76 while (rdtsc() < timeout);
79 void ndelay(unsigned int n)
81 _delay(n * cpu_khz / 1000000);
84 void mdelay(unsigned int m)
89 void delay(unsigned int s)
91 _delay(s * cpu_khz * 1000);