arch/arm/mach-s3c24xx/cpufreq-utils.c

   1 /*
   2  * Copyright (c) 2009 Simtec Electronics
   3  *      http://armlinux.simtec.co.uk/
   4  *      Ben Dooks <ben@simtec.co.uk>
   5  *
   6  * S3C24XX CPU Frequency scaling - utils for S3C2410/S3C2440/S3C2442
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11 */
  12
  13 #include <linux/kernel.h>
  14 #include <linux/errno.h>
  15 #include <linux/cpufreq.h>
  16 #include <linux/io.h>
  17 #include <linux/clk.h>
  18
  19 #include <mach/map.h>
  20 #include <mach/regs-clock.h>
  21
  22 #include <plat/cpu-freq-core.h>
  23
  24 #include "regs-mem.h"
  25
  26 /**
  27  * s3c2410_cpufreq_setrefresh - set SDRAM refresh value
  28  * @cfg: The frequency configuration
  29  *
  30  * Set the SDRAM refresh value appropriately for the configured
  31  * frequency.
  32  */
  33 void s3c2410_cpufreq_setrefresh(struct s3c_cpufreq_config *cfg)
  34 {
  35         struct s3c_cpufreq_board *board = cfg->board;
  36         unsigned long refresh;
  37         unsigned long refval;
  38
  39         /* Reduce both the refresh time (in ns) and the frequency (in MHz)
  40          * down to ensure that we do not overflow 32 bit numbers.
  41          *
  42          * This should work for HCLK up to 133MHz and refresh period up
  43          * to 30usec.
  44          */
  45
  46         refresh = (cfg->freq.hclk / 100) * (board->refresh / 10);
  47         refresh = DIV_ROUND_UP(refresh, (1000 * 1000)); /* apply scale  */
  48         refresh = (1 << 11) + 1 - refresh;
  49
  50         s3c_freq_dbg("%s: refresh value %lu\n", __func__, refresh);
  51
  52         refval = __raw_readl(S3C2410_REFRESH);
  53         refval &= ~((1 << 12) - 1);
  54         refval |= refresh;
  55         __raw_writel(refval, S3C2410_REFRESH);
  56 }
  57
  58 /**
  59  * s3c2410_set_fvco - set the PLL value
  60  * @cfg: The frequency configuration
  61  */
  62 void s3c2410_set_fvco(struct s3c_cpufreq_config *cfg)
  63 {
  64         if (!IS_ERR(cfg->mpll))
  65                 clk_set_rate(cfg->mpll, cfg->pll.frequency);
  66 }