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

   1 // SPDX-License-Identifier: GPL-2.0
   2 //
   3 // Copyright (c) 2009 Simtec Electronics
   4 //      http://armlinux.simtec.co.uk/
   5 //      Ben Dooks <ben@simtec.co.uk>
   6 //
   7 // S3C24XX CPU Frequency scaling - utils for S3C2410/S3C2440/S3C2442
   8
   9 #include <linux/kernel.h>
  10 #include <linux/errno.h>
  11 #include <linux/cpufreq.h>
  12 #include <linux/io.h>
  13 #include <linux/clk.h>
  14
  15 #include <mach/map.h>
  16 #include <mach/regs-clock.h>
  17
  18 #include <plat/cpu-freq-core.h>
  19
  20 #include "regs-mem.h"
  21
  22 /**
  23  * s3c2410_cpufreq_setrefresh - set SDRAM refresh value
  24  * @cfg: The frequency configuration
  25  *
  26  * Set the SDRAM refresh value appropriately for the configured
  27  * frequency.
  28  */
  29 void s3c2410_cpufreq_setrefresh(struct s3c_cpufreq_config *cfg)
  30 {
  31         struct s3c_cpufreq_board *board = cfg->board;
  32         unsigned long refresh;
  33         unsigned long refval;
  34
  35         /* Reduce both the refresh time (in ns) and the frequency (in MHz)
  36          * down to ensure that we do not overflow 32 bit numbers.
  37          *
  38          * This should work for HCLK up to 133MHz and refresh period up
  39          * to 30usec.
  40          */
  41
  42         refresh = (cfg->freq.hclk / 100) * (board->refresh / 10);
  43         refresh = DIV_ROUND_UP(refresh, (1000 * 1000)); /* apply scale  */
  44         refresh = (1 << 11) + 1 - refresh;
  45
  46         s3c_freq_dbg("%s: refresh value %lu\n", __func__, refresh);
  47
  48         refval = __raw_readl(S3C2410_REFRESH);
  49         refval &= ~((1 << 12) - 1);
  50         refval |= refresh;
  51         __raw_writel(refval, S3C2410_REFRESH);
  52 }
  53
  54 /**
  55  * s3c2410_set_fvco - set the PLL value
  56  * @cfg: The frequency configuration
  57  */
  58 void s3c2410_set_fvco(struct s3c_cpufreq_config *cfg)
  59 {
  60         if (!IS_ERR(cfg->mpll))
  61                 clk_set_rate(cfg->mpll, cfg->pll.frequency);
  62 }