drivers/cpufreq/davinci-cpufreq.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * CPU frequency scaling for DaVinci
   4  *
   5  * Copyright (C) 2009 Texas Instruments Incorporated - https://www.ti.com/
   6  *
   7  * Based on linux/arch/arm/plat-omap/cpu-omap.c. Original Copyright follows:
   8  *
   9  *  Copyright (C) 2005 Nokia Corporation
  10  *  Written by Tony Lindgren <tony@atomide.com>
  11  *
  12  *  Based on cpu-sa1110.c, Copyright (C) 2001 Russell King
  13  *
  14  * Copyright (C) 2007-2008 Texas Instruments, Inc.
  15  * Updated to support OMAP3
  16  * Rajendra Nayak <rnayak@ti.com>
  17  */
  18 #include <linux/types.h>
  19 #include <linux/cpufreq.h>
  20 #include <linux/init.h>
  21 #include <linux/err.h>
  22 #include <linux/clk.h>
  23 #include <linux/platform_data/davinci-cpufreq.h>
  24 #include <linux/platform_device.h>
  25 #include <linux/export.h>
  26
  27 struct davinci_cpufreq {
  28         struct device *dev;
  29         struct clk *armclk;
  30         struct clk *asyncclk;
  31         unsigned long asyncrate;
  32 };
  33 static struct davinci_cpufreq cpufreq;
  34
  35 static int davinci_target(struct cpufreq_policy *policy, unsigned int idx)
  36 {
  37         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  38         struct clk *armclk = cpufreq.armclk;
  39         unsigned int old_freq, new_freq;
  40         int ret = 0;
  41
  42         old_freq = policy->cur;
  43         new_freq = pdata->freq_table[idx].frequency;
  44
  45         /* if moving to higher frequency, up the voltage beforehand */
  46         if (pdata->set_voltage && new_freq > old_freq) {
  47                 ret = pdata->set_voltage(idx);
  48                 if (ret)
  49                         return ret;
  50         }
  51
  52         ret = clk_set_rate(armclk, new_freq * 1000);
  53         if (ret)
  54                 return ret;
  55
  56         if (cpufreq.asyncclk) {
  57                 ret = clk_set_rate(cpufreq.asyncclk, cpufreq.asyncrate);
  58                 if (ret)
  59                         return ret;
  60         }
  61
  62         /* if moving to lower freq, lower the voltage after lowering freq */
  63         if (pdata->set_voltage && new_freq < old_freq)
  64                 pdata->set_voltage(idx);
  65
  66         return 0;
  67 }
  68
  69 static int davinci_cpu_init(struct cpufreq_policy *policy)
  70 {
  71         int result = 0;
  72         struct davinci_cpufreq_config *pdata = cpufreq.dev->platform_data;
  73         struct cpufreq_frequency_table *freq_table = pdata->freq_table;
  74
  75         if (policy->cpu != 0)
  76                 return -EINVAL;
  77
  78         /* Finish platform specific initialization */
  79         if (pdata->init) {
  80                 result = pdata->init();
  81                 if (result)
  82                         return result;
  83         }
  84
  85         policy->clk = cpufreq.armclk;
  86
  87         /*
  88          * Time measurement across the target() function yields ~1500-1800us
  89          * time taken with no drivers on notification list.
  90          * Setting the latency to 2000 us to accommodate addition of drivers
  91          * to pre/post change notification list.
  92          */
  93         cpufreq_generic_init(policy, freq_table, 2000 * 1000);
  94         return 0;
  95 }
  96
  97 static struct cpufreq_driver davinci_driver = {
  98         .flags          = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
  99         .verify         = cpufreq_generic_frequency_table_verify,
 100         .target_index   = davinci_target,
 101         .get            = cpufreq_generic_get,
 102         .init           = davinci_cpu_init,
 103         .name           = "davinci",
 104         .attr           = cpufreq_generic_attr,
 105 };
 106
 107 static int __init davinci_cpufreq_probe(struct platform_device *pdev)
 108 {
 109         struct davinci_cpufreq_config *pdata = pdev->dev.platform_data;
 110         struct clk *asyncclk;
 111
 112         if (!pdata)
 113                 return -EINVAL;
 114         if (!pdata->freq_table)
 115                 return -EINVAL;
 116
 117         cpufreq.dev = &pdev->dev;
 118
 119         cpufreq.armclk = clk_get(NULL, "arm");
 120         if (IS_ERR(cpufreq.armclk)) {
 121                 dev_err(cpufreq.dev, "Unable to get ARM clock\n");
 122                 return PTR_ERR(cpufreq.armclk);
 123         }
 124
 125         asyncclk = clk_get(cpufreq.dev, "async");
 126         if (!IS_ERR(asyncclk)) {
 127                 cpufreq.asyncclk = asyncclk;
 128                 cpufreq.asyncrate = clk_get_rate(asyncclk);
 129         }
 130
 131         return cpufreq_register_driver(&davinci_driver);
 132 }
 133
 134 static void __exit davinci_cpufreq_remove(struct platform_device *pdev)
 135 {
 136         cpufreq_unregister_driver(&davinci_driver);
 137
 138         clk_put(cpufreq.armclk);
 139
 140         if (cpufreq.asyncclk)
 141                 clk_put(cpufreq.asyncclk);
 142 }
 143
 144 static struct platform_driver davinci_cpufreq_driver = {
 145         .driver = {
 146                 .name    = "cpufreq-davinci",
 147         },
 148         .remove_new = __exit_p(davinci_cpufreq_remove),
 149 };
 150
 151 int __init davinci_cpufreq_init(void)
 152 {
 153         return platform_driver_probe(&davinci_cpufreq_driver,
 154                                                         davinci_cpufreq_probe);
 155 }
 156