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 */ s3c2410_cpufreq_setrefresh(struct s3c_cpufreq_config * cfg)33void 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 */ s3c2410_set_fvco(struct s3c_cpufreq_config * cfg)62void 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 } 67