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s3c2410-cpufreq-utils.c
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1 /* linux/arch/arm/plat-s3c24xx/s3c2410-cpufreq-utils.c
2  *
3  * Copyright (c) 2009 Simtec Electronics
4  * http://armlinux.simtec.co.uk/
5  * Ben Dooks <[email protected]>
6  *
7  * S3C24XX CPU Frequency scaling - utils for S3C2410/S3C2440/S3C2442
8  *
9  * This program is free software; you can redistribute it and/or modify
10  * it under the terms of the GNU General Public License version 2 as
11  * published by the Free Software Foundation.
12 */
13 
14 #include <linux/kernel.h>
15 #include <linux/errno.h>
16 #include <linux/cpufreq.h>
17 #include <linux/io.h>
18 
19 #include <mach/map.h>
20 #include <mach/regs-mem.h>
21 #include <mach/regs-clock.h>
22 
23 #include <plat/cpu-freq-core.h>
24 
33 {
34  struct s3c_cpufreq_board *board = cfg->board;
35  unsigned long refresh;
36  unsigned long refval;
37 
38  /* Reduce both the refresh time (in ns) and the frequency (in MHz)
39  * down to ensure that we do not overflow 32 bit numbers.
40  *
41  * This should work for HCLK up to 133MHz and refresh period up
42  * to 30usec.
43  */
44 
45  refresh = (cfg->freq.hclk / 100) * (board->refresh / 10);
46  refresh = DIV_ROUND_UP(refresh, (1000 * 1000)); /* apply scale */
47  refresh = (1 << 11) + 1 - refresh;
48 
49  s3c_freq_dbg("%s: refresh value %lu\n", __func__, refresh);
50 
51  refval = __raw_readl(S3C2410_REFRESH);
52  refval &= ~((1 << 12) - 1);
53  refval |= refresh;
55 }
56 
62 {
63  __raw_writel(cfg->pll.index, S3C2410_MPLLCON);
64 }