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kernel/linux-imx6_3.14.28/arch/arm/mach-s3c24xx/cpufreq-utils.c 1.66 KB
6b13f685e   김민수   BSP 최초 추가
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  /*
   * Copyright (c) 2009 Simtec Electronics
   *	http://armlinux.simtec.co.uk/
   *	Ben Dooks <ben@simtec.co.uk>
   *
   * S3C24XX CPU Frequency scaling - utils for S3C2410/S3C2440/S3C2442
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
  */
  
  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/cpufreq.h>
  #include <linux/io.h>
  
  #include <mach/map.h>
  #include <mach/regs-clock.h>
  
  #include <plat/cpu-freq-core.h>
  
  #include "regs-mem.h"
  
  /**
   * s3c2410_cpufreq_setrefresh - set SDRAM refresh value
   * @cfg: The frequency configuration
   *
   * Set the SDRAM refresh value appropriately for the configured
   * frequency.
   */
  void s3c2410_cpufreq_setrefresh(struct s3c_cpufreq_config *cfg)
  {
  	struct s3c_cpufreq_board *board = cfg->board;
  	unsigned long refresh;
  	unsigned long refval;
  
  	/* Reduce both the refresh time (in ns) and the frequency (in MHz)
  	 * down to ensure that we do not overflow 32 bit numbers.
  	 *
  	 * This should work for HCLK up to 133MHz and refresh period up
  	 * to 30usec.
  	 */
  
  	refresh = (cfg->freq.hclk / 100) * (board->refresh / 10);
  	refresh = DIV_ROUND_UP(refresh, (1000 * 1000)); /* apply scale  */
  	refresh = (1 << 11) + 1 - refresh;
  
  	s3c_freq_dbg("%s: refresh value %lu
  ", __func__, refresh);
  
  	refval = __raw_readl(S3C2410_REFRESH);
  	refval &= ~((1 << 12) - 1);
  	refval |= refresh;
  	__raw_writel(refval, S3C2410_REFRESH);
  }
  
  /**
   * s3c2410_set_fvco - set the PLL value
   * @cfg: The frequency configuration
   */
  void s3c2410_set_fvco(struct s3c_cpufreq_config *cfg)
  {
  	__raw_writel(cfg->pll.driver_data, S3C2410_MPLLCON);
  }