linux/drivers/cpufreq/davinci-cpufreq.c
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   1/*
   2 * CPU frequency scaling for DaVinci
   3 *
   4 * Copyright (C) 2009 Texas Instruments Incorporated - http://www.ti.com/
   5 *
   6 * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
   7 *
   8 *  Copyright (C) 2005 Nokia Corporation
   9 *  Written by Tony Lindgren <tony@atomide.com>
  10 *
  11 *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
  12 *
  13 * Copyright (C) 2007-2008 Texas Instruments, Inc.
  14 * Updated to support OMAP3
  15 * Rajendra Nayak <rnayak@ti.com>
  16 *
  17 * This program is free software; you can redistribute it and/or modify
  18 * it under the terms of the GNU General Public License version 2 as
  19 * published by the Free Software Foundation.
  20 */
  21#include <linux/types.h>
  22#include <linux/cpufreq.h>
  23#include <linux/init.h>
  24#include <linux/err.h>
  25#include <linux/clk.h>
  26#include <linux/platform_device.h>
  27#include <linux/export.h>
  28
  29#include <mach/hardware.h>
  30#include <mach/cpufreq.h>
  31#include <mach/common.h>
  32
  33struct davinci_cpufreq {
  34        struct device *dev;
  35        struct clk *armclk;
  36        struct clk *asyncclk;
  37        unsigned long asyncrate;
  38};
  39static struct davinci_cpufreq cpufreq;
  40
  41static int davinci_verify_speed(struct cpufreq_policy *policy)
  42{
  43        struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  44        struct cpufreq_frequency_table *freq_table = pdata->freq_table;
  45        struct clk *armclk = cpufreq.armclk;
  46
  47        if (freq_table)
  48                return cpufreq_frequency_table_verify(policy, freq_table);
  49
  50        if (policy->cpu)
  51                return -EINVAL;
  52
  53        cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  54                                     policy->cpuinfo.max_freq);
  55
  56        policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
  57        policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
  58        cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  59                                                policy->cpuinfo.max_freq);
  60        return 0;
  61}
  62
  63static unsigned int davinci_getspeed(unsigned int cpu)
  64{
  65        if (cpu)
  66                return 0;
  67
  68        return clk_get_rate(cpufreq.armclk) / 1000;
  69}
  70
  71static int davinci_target(struct cpufreq_policy *policy,
  72                                unsigned int target_freq, unsigned int relation)
  73{
  74        int ret = 0;
  75        unsigned int idx;
  76        struct cpufreq_freqs freqs;
  77        struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  78        struct clk *armclk = cpufreq.armclk;
  79
  80        freqs.old = davinci_getspeed(0);
  81        freqs.new = clk_round_rate(armclk, target_freq * 1000) / 1000;
  82
  83        if (freqs.old == freqs.new)
  84                return ret;
  85
  86        dev_dbg(cpufreq.dev, "transition: %u --> %u\n", freqs.old, freqs.new);
  87
  88        ret = cpufreq_frequency_table_target(policy, pdata->freq_table,
  89                                                freqs.new, relation, &idx);
  90        if (ret)
  91                return -EINVAL;
  92
  93        cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  94
  95        /* if moving to higher frequency, up the voltage beforehand */
  96        if (pdata->set_voltage && freqs.new > freqs.old) {
  97                ret = pdata->set_voltage(idx);
  98                if (ret)
  99                        goto out;
 100        }
 101
 102        ret = clk_set_rate(armclk, idx);
 103        if (ret)
 104                goto out;
 105
 106        if (cpufreq.asyncclk) {
 107                ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
 108                if (ret)
 109                        goto out;
 110        }
 111
 112        /* if moving to lower freq, lower the voltage after lowering freq */
 113        if (pdata->set_voltage && freqs.new < freqs.old)
 114                pdata->set_voltage(idx);
 115
 116out:
 117        cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 118
 119        return ret;
 120}
 121
 122static int davinci_cpu_init(struct cpufreq_policy *policy)
 123{
 124        int result = 0;
 125        struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
 126        struct cpufreq_frequency_table *freq_table = pdata->freq_table;
 127
 128        if (policy->cpu != 0)
 129                return -EINVAL;
 130
 131        /* Finish platform specific initialization */
 132        if (pdata->init) {
 133                result = pdata->init();
 134                if (result)
 135                        return result;
 136        }
 137
 138        policy->cur = davinci_getspeed(0);
 139
 140        result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 141        if (result) {
 142                pr_err("%s: cpufreq_frequency_table_cpuinfo() failed",
 143                                __func__);
 144                return result;
 145        }
 146
 147        cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 148
 149        /*
 150         * Time measurement across the target() function yields ~1500-1800us
 151         * time taken with no drivers on notification list.
 152         * Setting the latency to 2000 us to accommodate addition of drivers
 153         * to pre/post change notification list.
 154         */
 155        policy->cpuinfo.transition_latency = 2000 * 1000;
 156        return 0;
 157}
 158
 159static int davinci_cpu_exit(struct cpufreq_policy *policy)
 160{
 161        cpufreq_frequency_table_put_attr(policy->cpu);
 162        return 0;
 163}
 164
 165static struct freq_attr *davinci_cpufreq_attr[] = {
 166        &cpufreq_freq_attr_scaling_available_freqs,
 167        NULL,
 168};
 169
 170static struct cpufreq_driver davinci_driver = {
 171        .flags          = CPUFREQ_STICKY,
 172        .verify         = davinci_verify_speed,
 173        .target         = davinci_target,
 174        .get            = davinci_getspeed,
 175        .init           = davinci_cpu_init,
 176        .exit           = davinci_cpu_exit,
 177        .name           = "davinci",
 178        .attr           = davinci_cpufreq_attr,
 179};
 180
 181static int __init davinci_cpufreq_probe(struct platform_device *pdev)
 182{
 183        struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
 184        struct clk *asyncclk;
 185
 186        if (!pdata)
 187                return -EINVAL;
 188        if (!pdata->freq_table)
 189                return -EINVAL;
 190
 191        cpufreq.dev = &pdev->dev;
 192
 193        cpufreq.armclk = clk_get(NULL, "arm");
 194        if (IS_ERR(cpufreq.armclk)) {
 195                dev_err(cpufreq.dev, "Unable to get ARM clock\n");
 196                return PTR_ERR(cpufreq.armclk);
 197        }
 198
 199        asyncclk = clk_get(cpufreq.dev, "async");
 200        if (!IS_ERR(asyncclk)) {
 201                cpufreq.asyncclk = asyncclk;
 202                cpufreq.asyncrate = clk_get_rate(asyncclk);
 203        }
 204
 205        return cpufreq_register_driver(&davinci_driver);
 206}
 207
 208static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
 209{
 210        clk_put(cpufreq.armclk);
 211
 212        if (cpufreq.asyncclk)
 213                clk_put(cpufreq.asyncclk);
 214
 215        return cpufreq_unregister_driver(&davinci_driver);
 216}
 217
 218static struct platform_driver davinci_cpufreq_driver = {
 219        .driver = {
 220                .name    = "cpufreq-davinci",
 221                .owner   = THIS_MODULE,
 222        },
 223        .remove = __exit_p(davinci_cpufreq_remove),
 224};
 225
 226int __init davinci_cpufreq_init(void)
 227{
 228        return platform_driver_probe(&davinci_cpufreq_driver,
 229                                                        davinci_cpufreq_probe);
 230}
 231
 232
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