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_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
  63 static 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
  71 static 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
 116 out:
 117         if (ret)
 118                 freqs.new = freqs.old;
 119
 120         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
 121
 122         return ret;
 123 }
 124
 125 static int davinci_cpu_init(struct cpufreq_policy *policy)
 126 {
 127         int result = 0;
 128         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
 129         struct cpufreq_frequency_table *freq_table = pdata->freq_table;
 130
 131         if (policy->cpu != 0)
 132                 return -EINVAL;
 133
 134         /* Finish platform specific initialization */
 135         if (pdata->init) {
 136                 result = pdata->init();
 137                 if (result)
 138                         return result;
 139         }
 140
 141         policy->cur = davinci_getspeed(0);
 142
 143         result = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 144         if (result) {
 145                 pr_err("%s: cpufreq_frequency_table_cpuinfo() failed",
 146                                 __func__);
 147                 return result;
 148         }
 149
 150         cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 151
 152         /*
 153          * Time measurement across the target() function yields ~1500-1800us
 154          * time taken with no drivers on notification list.
 155          * Setting the latency to 2000 us to accommodate addition of drivers
 156          * to pre/post change notification list.
 157          */
 158         policy->cpuinfo.transition_latency = 2000 * 1000;
 159         return 0;
 160 }
 161
 162 static int davinci_cpu_exit(struct cpufreq_policy *policy)
 163 {
 164         cpufreq_frequency_table_put_attr(policy->cpu);
 165         return 0;
 166 }
 167
 168 static struct freq_attr *davinci_cpufreq_attr[] = {
 169         &cpufreq_freq_attr_scaling_available_freqs,
 170         NULL,
 171 };
 172
 173 static struct cpufreq_driver davinci_driver = {
 174         .flags          = CPUFREQ_STICKY,
 175         .verify         = davinci_verify_speed,
 176         .target         = davinci_target,
 177         .get            = davinci_getspeed,
 178         .init           = davinci_cpu_init,
 179         .exit           = davinci_cpu_exit,
 180         .name           = "davinci",
 181         .attr           = davinci_cpufreq_attr,
 182 };
 183
 184 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
 185 {
 186         struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
 187         struct clk *asyncclk;
 188
 189         if (!pdata)
 190                 return -EINVAL;
 191         if (!pdata->freq_table)
 192                 return -EINVAL;
 193
 194         cpufreq.dev = &pdev->dev;
 195
 196         cpufreq.armclk = clk_get(NULL, "arm");
 197         if (IS_ERR(cpufreq.armclk)) {
 198                 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
 199                 return PTR_ERR(cpufreq.armclk);
 200         }
 201
 202         asyncclk = clk_get(cpufreq.dev, "async");
 203         if (!IS_ERR(asyncclk)) {
 204                 cpufreq.asyncclk = asyncclk;
 205                 cpufreq.asyncrate = clk_get_rate(asyncclk);
 206         }
 207
 208         return cpufreq_register_driver(&davinci_driver);
 209 }
 210
 211 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
 212 {
 213         clk_put(cpufreq.armclk);
 214
 215         if (cpufreq.asyncclk)
 216                 clk_put(cpufreq.asyncclk);
 217
 218         return cpufreq_unregister_driver(&davinci_driver);
 219 }
 220
 221 static struct platform_driver davinci_cpufreq_driver = {
 222         .driver = {
 223                 .name    = "cpufreq-davinci",
 224                 .owner   = THIS_MODULE,
 225         },
 226         .remove = __exit_p(davinci_cpufreq_remove),
 227 };
 228
 229 int __init davinci_cpufreq_init(void)
 230 {
 231         return platform_driver_probe(&davinci_cpufreq_driver,
 232                                                         davinci_cpufreq_probe);
 233 }
 234