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_target(struct cpufreq_policy *policy, unsigned int idx)
  42 {
  43         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  44         struct clk *armclk = cpufreq.armclk;
  45         unsigned int old_freq, new_freq;
  46         int ret = 0;
  47
  48         old_freq = policy->cur;
  49         new_freq = pdata->freq_table[idx].frequency;
  50
  51         /* if moving to higher frequency, up the voltage beforehand */
  52         if (pdata->set_voltage && new_freq > old_freq) {
  53                 ret = pdata->set_voltage(idx);
  54                 if (ret)
  55                         return ret;
  56         }
  57
  58         ret = clk_set_rate(armclk, idx);
  59         if (ret)
  60                 return ret;
  61
  62         if (cpufreq.asyncclk) {
  63                 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
  64                 if (ret)
  65                         return ret;
  66         }
  67
  68         /* if moving to lower freq, lower the voltage after lowering freq */
  69         if (pdata->set_voltage && new_freq < old_freq)
  70                 pdata->set_voltage(idx);
  71
  72         return 0;
  73 }
  74
  75 static int davinci_cpu_init(struct cpufreq_policy *policy)
  76 {
  77         int result = 0;
  78         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  79         struct cpufreq_frequency_table *freq_table = pdata->freq_table;
  80
  81         if (policy->cpu != 0)
  82                 return -EINVAL;
  83
  84         /* Finish platform specific initialization */
  85         if (pdata->init) {
  86                 result = pdata->init();
  87                 if (result)
  88                         return result;
  89         }
  90
  91         policy->clk = cpufreq.armclk;
  92
  93         /*
  94          * Time measurement across the target() function yields ~1500-1800us
  95          * time taken with no drivers on notification list.
  96          * Setting the latency to 2000 us to accommodate addition of drivers
  97          * to pre/post change notification list.
  98          */
  99         return cpufreq_generic_init(policy, freq_table, 2000 * 1000);
 100 }
 101
 102 static struct cpufreq_driver davinci_driver = {
 103         .flags          = CPUFREQ_STICKY | CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 104         .verify         = cpufreq_generic_frequency_table_verify,
 105         .target_index   = davinci_target,
 106         .get            = cpufreq_generic_get,
 107         .init           = davinci_cpu_init,
 108         .name           = "davinci",
 109         .attr           = cpufreq_generic_attr,
 110 };
 111
 112 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
 113 {
 114         struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
 115         struct clk *asyncclk;
 116
 117         if (!pdata)
 118                 return -EINVAL;
 119         if (!pdata->freq_table)
 120                 return -EINVAL;
 121
 122         cpufreq.dev = &pdev->dev;
 123
 124         cpufreq.armclk = clk_get(NULL, "arm");
 125         if (IS_ERR(cpufreq.armclk)) {
 126                 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
 127                 return PTR_ERR(cpufreq.armclk);
 128         }
 129
 130         asyncclk = clk_get(cpufreq.dev, "async");
 131         if (!IS_ERR(asyncclk)) {
 132                 cpufreq.asyncclk = asyncclk;
 133                 cpufreq.asyncrate = clk_get_rate(asyncclk);
 134         }
 135
 136         return cpufreq_register_driver(&davinci_driver);
 137 }
 138
 139 static int __exit davinci_cpufreq_remove(struct platform_device *pdev)
 140 {
 141         clk_put(cpufreq.armclk);
 142
 143         if (cpufreq.asyncclk)
 144                 clk_put(cpufreq.asyncclk);
 145
 146         return cpufreq_unregister_driver(&davinci_driver);
 147 }
 148
 149 static struct platform_driver davinci_cpufreq_driver = {
 150         .driver = {
 151                 .name    = "cpufreq-davinci",
 152         },
 153         .remove = __exit_p(davinci_cpufreq_remove),
 154 };
 155
 156 int __init davinci_cpufreq_init(void)
 157 {
 158         return platform_driver_probe(&davinci_cpufreq_driver,
 159                                                         davinci_cpufreq_probe);
 160 }
 161