LXR linux/drivers/cpufreq/davinci-cpufreq.c

   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_cpu_limits(policy);
  54        policy->min = clk_round_rate(armclk, policy->min * 1000) / 1000;
  55        policy->max = clk_round_rate(armclk, policy->max * 1000) / 1000;
  56        cpufreq_verify_within_limits(policy, policy->cpuinfo.min_freq,
  57                                                policy->cpuinfo.max_freq);
  58        return 0;
  59}
  60
  61static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)
  62{
  63        struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  64        struct clk *armclk = cpufreq.armclk;
  65        unsigned int old_freq, new_freq;
  66        int ret = 0;
  67
  68        old_freq = policy->cur;
  69        new_freq = pdata->freq_table[idx].frequency;
  70
  71        /* if moving to higher frequency, up the voltage beforehand */
  72        if (pdata->set_voltage && new_freq > old_freq) {
  73                ret = pdata->set_voltage(idx);
  74                if (ret)
  75                        return ret;
  76        }
  77
  78        ret = clk_set_rate(armclk, idx);
  79        if (ret)
  80                return ret;
  81
  82        if (cpufreq.asyncclk) {
  83                ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
  84                if (ret)
  85                        return ret;
  86        }
  87
  88        /* if moving to lower freq, lower the voltage after lowering freq */
  89        if (pdata->set_voltage && new_freq < old_freq)
  90                pdata->set_voltage(idx);
  91
  92        return 0;
  93}
  94
  95static int davinci_cpu_init(struct cpufreq_policy *policy)
  96{
  97        int result = 0;
  98        struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  99        struct cpufreq_frequency_table *freq_table = pdata->freq_table;
 100
 101        if (policy->cpu != 0)
 102                return -EINVAL;
 103
 104        /* Finish platform specific initialization */
 105        if (pdata->init) {
 106                result = pdata->init();
 107                if (result)
 108                        return result;
 109        }
 110
 111        policy->clk = cpufreq.armclk;
 112
 113        /*
 114         * Time measurement across the target() function yields ~1500-1800us
 115         * time taken with no drivers on notification list.
 116         * Setting the latency to 2000 us to accommodate addition of drivers
 117         * to pre/post change notification list.
 118         */
 119        return cpufreq_generic_init(policy, freq_table, 2000 * 1000);
 120}
 121
 122static struct cpufreq_driver davinci_driver = {
 123        .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 124        .verify         = davinci_verify_speed,
 125        .target_index   = davinci_target,
 126        .get            = cpufreq_generic_get,
 127        .init           = davinci_cpu_init,
 128        .name           = "davinci",
 129        .attr           = cpufreq_generic_attr,
 130};
 131
 132static int __init davinci_cpufreq_probe(struct platform_device *pdev)
 133{
 134        struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
 135        struct clk *asyncclk;
 136
 137        if (!pdata)
 138                return -EINVAL;
 139        if (!pdata->freq_table)
 140                return -EINVAL;
 141
 142        cpufreq.dev = &pdev->dev;
 143
 144        cpufreq.armclk = clk_get(NULL, "arm");
 145        if (IS_ERR(cpufreq.armclk)) {
 146                dev_err(cpufreq.dev, "Unable to get ARM clock\n");
 147                return PTR_ERR(cpufreq.armclk);
 148        }
 149
 150        asyncclk = clk_get(cpufreq.dev, "async");
 151        if (!IS_ERR(asyncclk)) {
 152                cpufreq.asyncclk = asyncclk;
 153                cpufreq.asyncrate = clk_get_rate(asyncclk);
 154        }
 155
 156        return cpufreq_register_driver(&davinci_driver);
 157}
 158
 159static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
 160{
 161        clk_put(cpufreq.armclk);
 162
 163        if (cpufreq.asyncclk)
 164                clk_put(cpufreq.asyncclk);
 165
 166        return cpufreq_unregister_driver(&davinci_driver);
 167}
 168
 169static struct platform_driver davinci_cpufreq_driver = {
 170        .driver = {
 171                .name    = "cpufreq-davinci",
 172        },
 173        .remove = __exit_p(davinci_cpufreq_remove),
 174};
 175
 176int __init davinci_cpufreq_init(void)
 177{
 178        return platform_driver_probe(&davinci_cpufreq_driver,
 179                                                        davinci_cpufreq_probe);
 180}
 181
 182