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
  33 struct davinci_cpufreq {
  34         struct device *dev;
  35         struct clk *armclk;
  36         struct clk *asyncclk;
  37         unsigned long asyncrate;
  38 };
  39 static struct davinci_cpufreq cpufreq;
  40
  41 static 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
  61 static unsigned int davinci_getspeed(unsigned int cpu)
  62 {
  63         if (cpu)
  64                 return 0;
  65
  66         return clk_get_rate(cpufreq.armclk) / 1000;
  67 }
  68
  69 static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)
  70 {
  71         int ret = 0;
  72         struct cpufreq_freqs freqs;
  73         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  74         struct clk *armclk = cpufreq.armclk;
  75
  76         freqs.old = davinci_getspeed(0);
  77         freqs.new = pdata->freq_table[idx].frequency;
  78
  79         dev_dbg(cpufreq.dev, "transition: %u --> %u\n", freqs.old, freqs.new);
  80
  81         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  82
  83         /* if moving to higher frequency, up the voltage beforehand */
  84         if (pdata->set_voltage && freqs.new > freqs.old) {
  85                 ret = pdata->set_voltage(idx);
  86                 if (ret)
  87                         goto out;
  88         }
  89
  90         ret = clk_set_rate(armclk, idx);
  91         if (ret)
  92                 goto out;
  93
  94         if (cpufreq.asyncclk) {
  95                 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
  96                 if (ret)
  97                         goto out;
  98         }
  99
 100         /* if moving to lower freq, lower the voltage after lowering freq */
 101         if (pdata->set_voltage && freqs.new < freqs.old)
 102                 pdata->set_voltage(idx);
 103
 104 out:
 105         if (ret)
 106                 freqs.new = freqs.old;
 107
 108         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 109
 110         return ret;
 111 }
 112
 113 static int davinci_cpu_init(struct cpufreq_policy *policy)
 114 {
 115         int result = 0;
 116         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
 117         struct cpufreq_frequency_table *freq_table = pdata->freq_table;
 118
 119         if (policy->cpu != 0)
 120                 return -EINVAL;
 121
 122         /* Finish platform specific initialization */
 123         if (pdata->init) {
 124                 result = pdata->init();
 125                 if (result)
 126                         return result;
 127         }
 128
 129         /*
 130          * Time measurement across the target() function yields ~1500-1800us
 131          * time taken with no drivers on notification list.
 132          * Setting the latency to 2000 us to accommodate addition of drivers
 133          * to pre/post change notification list.
 134          */
 135         return cpufreq_generic_init(policy, freq_table, 2000 * 1000);
 136 }
 137
 138 static struct cpufreq_driver davinci_driver = {
 139         .flags          = CPUFREQ_STICKY,
 140         .verify         = davinci_verify_speed,
 141         .target_index   = davinci_target,
 142         .get            = davinci_getspeed,
 143         .init           = davinci_cpu_init,
 144         .exit           = cpufreq_generic_exit,
 145         .name           = "davinci",
 146         .attr           = cpufreq_generic_attr,
 147 };
 148
 149 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
 150 {
 151         struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
 152         struct clk *asyncclk;
 153
 154         if (!pdata)
 155                 return -EINVAL;
 156         if (!pdata->freq_table)
 157                 return -EINVAL;
 158
 159         cpufreq.dev = &pdev->dev;
 160
 161         cpufreq.armclk = clk_get(NULL, "arm");
 162         if (IS_ERR(cpufreq.armclk)) {
 163                 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
 164                 return PTR_ERR(cpufreq.armclk);
 165         }
 166
 167         asyncclk = clk_get(cpufreq.dev, "async");
 168         if (!IS_ERR(asyncclk)) {
 169                 cpufreq.asyncclk = asyncclk;
 170                 cpufreq.asyncrate = clk_get_rate(asyncclk);
 171         }
 172
 173         return cpufreq_register_driver(&davinci_driver);
 174 }
 175
 176 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
 177 {
 178         clk_put(cpufreq.armclk);
 179
 180         if (cpufreq.asyncclk)
 181                 clk_put(cpufreq.asyncclk);
 182
 183         return cpufreq_unregister_driver(&davinci_driver);
 184 }
 185
 186 static struct platform_driver davinci_cpufreq_driver = {
 187         .driver = {
 188                 .name    = "cpufreq-davinci",
 189                 .owner   = THIS_MODULE,
 190         },
 191         .remove = __exit_p(davinci_cpufreq_remove),
 192 };
 193
 194 int __init davinci_cpufreq_init(void)
 195 {
 196         return platform_driver_probe(&davinci_cpufreq_driver,
 197                                                         davinci_cpufreq_probe);
 198 }
 199