310 lines
7.1 KiB
C
310 lines
7.1 KiB
C
/*
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* Copyright (c) 2006-2009 Simtec Electronics
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* http://armlinux.simtec.co.uk/
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* Ben Dooks <ben@simtec.co.uk>
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* Vincent Sanders <vince@simtec.co.uk>
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*
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* S3C2440/S3C2442 CPU Frequency scaling
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*/
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#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/ioport.h>
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#include <linux/cpufreq.h>
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#include <linux/device.h>
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#include <linux/delay.h>
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#include <linux/clk.h>
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#include <linux/err.h>
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#include <linux/io.h>
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#include <asm/mach/arch.h>
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#include <asm/mach/map.h>
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#include <mach/regs-clock.h>
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#include <plat/cpu.h>
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#include <plat/cpu-freq-core.h>
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static struct clk *xtal;
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static struct clk *fclk;
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static struct clk *hclk;
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static struct clk *armclk;
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/* HDIV: 1, 2, 3, 4, 6, 8 */
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static inline int within_khz(unsigned long a, unsigned long b)
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{
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long diff = a - b;
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return (diff >= -1000 && diff <= 1000);
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}
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/**
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* s3c2440_cpufreq_calcdivs - calculate divider settings
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* @cfg: The cpu frequency settings.
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*
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* Calcualte the divider values for the given frequency settings
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* specified in @cfg. The values are stored in @cfg for later use
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* by the relevant set routine if the request settings can be reached.
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*/
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static int s3c2440_cpufreq_calcdivs(struct s3c_cpufreq_config *cfg)
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{
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unsigned int hdiv, pdiv;
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unsigned long hclk, fclk, armclk;
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unsigned long hclk_max;
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fclk = cfg->freq.fclk;
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armclk = cfg->freq.armclk;
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hclk_max = cfg->max.hclk;
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s3c_freq_dbg("%s: fclk is %lu, armclk %lu, max hclk %lu\n",
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__func__, fclk, armclk, hclk_max);
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if (armclk > fclk) {
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pr_warn("%s: armclk > fclk\n", __func__);
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armclk = fclk;
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}
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/* if we are in DVS, we need HCLK to be <= ARMCLK */
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if (armclk < fclk && armclk < hclk_max)
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hclk_max = armclk;
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for (hdiv = 1; hdiv < 9; hdiv++) {
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if (hdiv == 5 || hdiv == 7)
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hdiv++;
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hclk = (fclk / hdiv);
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if (hclk <= hclk_max || within_khz(hclk, hclk_max))
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break;
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}
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s3c_freq_dbg("%s: hclk %lu, div %d\n", __func__, hclk, hdiv);
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if (hdiv > 8)
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goto invalid;
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pdiv = (hclk > cfg->max.pclk) ? 2 : 1;
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if ((hclk / pdiv) > cfg->max.pclk)
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pdiv++;
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s3c_freq_dbg("%s: pdiv %d\n", __func__, pdiv);
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if (pdiv > 2)
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goto invalid;
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pdiv *= hdiv;
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/* calculate a valid armclk */
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if (armclk < hclk)
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armclk = hclk;
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/* if we're running armclk lower than fclk, this really means
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* that the system should go into dvs mode, which means that
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* armclk is connected to hclk. */
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if (armclk < fclk) {
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cfg->divs.dvs = 1;
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armclk = hclk;
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} else
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cfg->divs.dvs = 0;
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cfg->freq.armclk = armclk;
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/* store the result, and then return */
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cfg->divs.h_divisor = hdiv;
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cfg->divs.p_divisor = pdiv;
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return 0;
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invalid:
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return -EINVAL;
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}
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#define CAMDIVN_HCLK_HALF (S3C2440_CAMDIVN_HCLK3_HALF | \
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S3C2440_CAMDIVN_HCLK4_HALF)
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/**
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* s3c2440_cpufreq_setdivs - set the cpu frequency divider settings
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* @cfg: The cpu frequency settings.
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*
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* Set the divisors from the settings in @cfg, which where generated
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* during the calculation phase by s3c2440_cpufreq_calcdivs().
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*/
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static void s3c2440_cpufreq_setdivs(struct s3c_cpufreq_config *cfg)
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{
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unsigned long clkdiv, camdiv;
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s3c_freq_dbg("%s: divisors: h=%d, p=%d\n", __func__,
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cfg->divs.h_divisor, cfg->divs.p_divisor);
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clkdiv = __raw_readl(S3C2410_CLKDIVN);
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camdiv = __raw_readl(S3C2440_CAMDIVN);
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clkdiv &= ~(S3C2440_CLKDIVN_HDIVN_MASK | S3C2440_CLKDIVN_PDIVN);
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camdiv &= ~CAMDIVN_HCLK_HALF;
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switch (cfg->divs.h_divisor) {
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case 1:
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clkdiv |= S3C2440_CLKDIVN_HDIVN_1;
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break;
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case 2:
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clkdiv |= S3C2440_CLKDIVN_HDIVN_2;
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break;
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case 6:
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camdiv |= S3C2440_CAMDIVN_HCLK3_HALF;
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case 3:
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clkdiv |= S3C2440_CLKDIVN_HDIVN_3_6;
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break;
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case 8:
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camdiv |= S3C2440_CAMDIVN_HCLK4_HALF;
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case 4:
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clkdiv |= S3C2440_CLKDIVN_HDIVN_4_8;
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break;
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default:
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BUG(); /* we don't expect to get here. */
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}
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if (cfg->divs.p_divisor != cfg->divs.h_divisor)
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clkdiv |= S3C2440_CLKDIVN_PDIVN;
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/* todo - set pclk. */
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/* Write the divisors first with hclk intentionally halved so that
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* when we write clkdiv we will under-frequency instead of over. We
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* then make a short delay and remove the hclk halving if necessary.
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*/
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__raw_writel(camdiv | CAMDIVN_HCLK_HALF, S3C2440_CAMDIVN);
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__raw_writel(clkdiv, S3C2410_CLKDIVN);
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ndelay(20);
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__raw_writel(camdiv, S3C2440_CAMDIVN);
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clk_set_parent(armclk, cfg->divs.dvs ? hclk : fclk);
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}
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static int run_freq_for(unsigned long max_hclk, unsigned long fclk,
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int *divs,
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struct cpufreq_frequency_table *table,
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size_t table_size)
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{
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unsigned long freq;
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int index = 0;
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int div;
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for (div = *divs; div > 0; div = *divs++) {
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freq = fclk / div;
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if (freq > max_hclk && div != 1)
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continue;
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freq /= 1000; /* table is in kHz */
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index = s3c_cpufreq_addfreq(table, index, table_size, freq);
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if (index < 0)
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break;
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}
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return index;
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}
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static int hclk_divs[] = { 1, 2, 3, 4, 6, 8, -1 };
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static int s3c2440_cpufreq_calctable(struct s3c_cpufreq_config *cfg,
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struct cpufreq_frequency_table *table,
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size_t table_size)
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{
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int ret;
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WARN_ON(cfg->info == NULL);
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WARN_ON(cfg->board == NULL);
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ret = run_freq_for(cfg->info->max.hclk,
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cfg->info->max.fclk,
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hclk_divs,
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table, table_size);
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s3c_freq_dbg("%s: returning %d\n", __func__, ret);
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return ret;
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}
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static struct s3c_cpufreq_info s3c2440_cpufreq_info = {
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.max = {
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.fclk = 400000000,
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.hclk = 133333333,
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.pclk = 66666666,
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},
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.locktime_m = 300,
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.locktime_u = 300,
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.locktime_bits = 16,
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.name = "s3c244x",
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.calc_iotiming = s3c2410_iotiming_calc,
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.set_iotiming = s3c2410_iotiming_set,
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.get_iotiming = s3c2410_iotiming_get,
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.set_fvco = s3c2410_set_fvco,
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.set_refresh = s3c2410_cpufreq_setrefresh,
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.set_divs = s3c2440_cpufreq_setdivs,
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.calc_divs = s3c2440_cpufreq_calcdivs,
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.calc_freqtable = s3c2440_cpufreq_calctable,
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.debug_io_show = s3c_cpufreq_debugfs_call(s3c2410_iotiming_debugfs),
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};
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static int s3c2440_cpufreq_add(struct device *dev,
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struct subsys_interface *sif)
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{
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xtal = s3c_cpufreq_clk_get(NULL, "xtal");
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hclk = s3c_cpufreq_clk_get(NULL, "hclk");
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fclk = s3c_cpufreq_clk_get(NULL, "fclk");
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armclk = s3c_cpufreq_clk_get(NULL, "armclk");
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if (IS_ERR(xtal) || IS_ERR(hclk) || IS_ERR(fclk) || IS_ERR(armclk)) {
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pr_err("%s: failed to get clocks\n", __func__);
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return -ENOENT;
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}
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return s3c_cpufreq_register(&s3c2440_cpufreq_info);
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}
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static struct subsys_interface s3c2440_cpufreq_interface = {
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.name = "s3c2440_cpufreq",
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.subsys = &s3c2440_subsys,
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.add_dev = s3c2440_cpufreq_add,
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};
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static int s3c2440_cpufreq_init(void)
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{
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return subsys_interface_register(&s3c2440_cpufreq_interface);
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}
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/* arch_initcall adds the clocks we need, so use subsys_initcall. */
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subsys_initcall(s3c2440_cpufreq_init);
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static struct subsys_interface s3c2442_cpufreq_interface = {
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.name = "s3c2442_cpufreq",
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.subsys = &s3c2442_subsys,
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.add_dev = s3c2440_cpufreq_add,
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};
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static int s3c2442_cpufreq_init(void)
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{
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return subsys_interface_register(&s3c2442_cpufreq_interface);
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}
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subsys_initcall(s3c2442_cpufreq_init);
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