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_data/davinci-cpufreq.h>
  27 #include <linux/platform_device.h>
  28 #include <linux/export.h>
  29
  30 struct davinci_cpufreq {
  31         struct device *dev;
  32         struct clk *armclk;
  33         struct clk *asyncclk;
  34         unsigned long asyncrate;
  35 };
  36 static struct davinci_cpufreq cpufreq;
  37
  38 static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)
  39 {
  40         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  41         struct clk *armclk = cpufreq.armclk;
  42         unsigned int old_freq, new_freq;
  43         int ret = 0;
  44
  45         old_freq = policy->cur;
  46         new_freq = pdata->freq_table[idx].frequency;
  47
  48         /* if moving to higher frequency, up the voltage beforehand */
  49         if (pdata->set_voltage && new_freq > old_freq) {
  50                 ret = pdata->set_voltage(idx);
  51                 if (ret)
  52                         return ret;
  53         }
  54
  55         ret = clk_set_rate(armclk, new_freq * 1000);
  56         if (ret)
  57                 return ret;
  58
  59         if (cpufreq.asyncclk) {
  60                 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
  61                 if (ret)
  62                         return ret;
  63         }
  64
  65         /* if moving to lower freq, lower the voltage after lowering freq */
  66         if (pdata->set_voltage && new_freq < old_freq)
  67                 pdata->set_voltage(idx);
  68
  69         return 0;
  70 }
  71
  72 static int davinci_cpu_init(struct cpufreq_policy *policy)
  73 {
  74         int result = 0;
  75         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  76         struct cpufreq_frequency_table *freq_table = pdata->freq_table;
  77
  78         if (policy->cpu != 0)
  79                 return -EINVAL;
  80
  81         /* Finish platform specific initialization */
  82         if (pdata->init) {
  83                 result = pdata->init();
  84                 if (result)
  85                         return result;
  86         }
  87
  88         policy->clk = cpufreq.armclk;
  89
  90         /*
  91          * Time measurement across the target() function yields ~1500-1800us
  92          * time taken with no drivers on notification list.
  93          * Setting the latency to 2000 us to accommodate addition of drivers
  94          * to pre/post change notification list.
  95          */
  96         return cpufreq_generic_init(policy, freq_table, 2000 * 1000);
  97 }
  98
  99 static struct cpufreq_driver davinci_driver = {
 100         .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 101         .verify         = cpufreq_generic_frequency_table_verify,
 102         .target_index   = davinci_target,
 103         .get            = cpufreq_generic_get,
 104         .init           = davinci_cpu_init,
 105         .name           = "davinci",
 106         .attr           = cpufreq_generic_attr,
 107 };
 108
 109 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
 110 {
 111         struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
 112         struct clk *asyncclk;
 113
 114         if (!pdata)
 115                 return -EINVAL;
 116         if (!pdata->freq_table)
 117                 return -EINVAL;
 118
 119         cpufreq.dev = &pdev->dev;
 120
 121         cpufreq.armclk = clk_get(NULL, "arm");
 122         if (IS_ERR(cpufreq.armclk)) {
 123                 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
 124                 return PTR_ERR(cpufreq.armclk);
 125         }
 126
 127         asyncclk = clk_get(cpufreq.dev, "async");
 128         if (!IS_ERR(asyncclk)) {
 129                 cpufreq.asyncclk = asyncclk;
 130                 cpufreq.asyncrate = clk_get_rate(asyncclk);
 131         }
 132
 133         return cpufreq_register_driver(&davinci_driver);
 134 }
 135
 136 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
 137 {
 138         clk_put(cpufreq.armclk);
 139
 140         if (cpufreq.asyncclk)
 141                 clk_put(cpufreq.asyncclk);
 142
 143         return cpufreq_unregister_driver(&davinci_driver);
 144 }
 145
 146 static struct platform_driver davinci_cpufreq_driver = {
 147         .driver = {
 148                 .name    = "cpufreq-davinci",
 149         },
 150         .remove = __exit_p(davinci_cpufreq_remove),
 151 };
 152
 153 int __init davinci_cpufreq_init(void)
 154 {
 155         return platform_driver_probe(&davinci_cpufreq_driver,
 156                                                         davinci_cpufreq_probe);
 157 }
 158