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 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
  95 static 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
 122 static 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
 132 static 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
 159 static 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
 169 static struct platform_driver davinci_cpufreq_driver = {
 170         .driver = {
 171                 .name    = "cpufreq-davinci",
 172         },
 173         .remove = __exit_p(davinci_cpufreq_remove),
 174 };
 175
 176 int __init davinci_cpufreq_init(void)
 177 {
 178         return platform_driver_probe(&davinci_cpufreq_driver,
 179                                                         davinci_cpufreq_probe);
 180 }
 181