drivers/cpufreq/tegra-cpufreq.c

   1 /*
   2  * Copyright (C) 2010 Google, Inc.
   3  *
   4  * Author:
   5  *      Colin Cross <ccross@google.com>
   6  *      Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation
   7  *
   8  * This software is licensed under the terms of the GNU General Public
   9  * License version 2, as published by the Free Software Foundation, and
  10  * may be copied, distributed, and modified under those terms.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  */
  18
  19 #include <linux/kernel.h>
  20 #include <linux/module.h>
  21 #include <linux/types.h>
  22 #include <linux/sched.h>
  23 #include <linux/cpufreq.h>
  24 #include <linux/delay.h>
  25 #include <linux/init.h>
  26 #include <linux/err.h>
  27 #include <linux/clk.h>
  28 #include <linux/io.h>
  29
  30 static struct cpufreq_frequency_table freq_table[] = {
  31         { .frequency = 216000 },
  32         { .frequency = 312000 },
  33         { .frequency = 456000 },
  34         { .frequency = 608000 },
  35         { .frequency = 760000 },
  36         { .frequency = 816000 },
  37         { .frequency = 912000 },
  38         { .frequency = 1000000 },
  39         { .frequency = CPUFREQ_TABLE_END },
  40 };
  41
  42 #define NUM_CPUS        2
  43
  44 static struct clk *cpu_clk;
  45 static struct clk *pll_x_clk;
  46 static struct clk *pll_p_clk;
  47 static struct clk *emc_clk;
  48
  49 static int tegra_cpu_clk_set_rate(unsigned long rate)
  50 {
  51         int ret;
  52
  53         /*
  54          * Take an extra reference to the main pll so it doesn't turn
  55          * off when we move the cpu off of it
  56          */
  57         clk_prepare_enable(pll_x_clk);
  58
  59         ret = clk_set_parent(cpu_clk, pll_p_clk);
  60         if (ret) {
  61                 pr_err("Failed to switch cpu to clock pll_p\n");
  62                 goto out;
  63         }
  64
  65         if (rate == clk_get_rate(pll_p_clk))
  66                 goto out;
  67
  68         ret = clk_set_rate(pll_x_clk, rate);
  69         if (ret) {
  70                 pr_err("Failed to change pll_x to %lu\n", rate);
  71                 goto out;
  72         }
  73
  74         ret = clk_set_parent(cpu_clk, pll_x_clk);
  75         if (ret) {
  76                 pr_err("Failed to switch cpu to clock pll_x\n");
  77                 goto out;
  78         }
  79
  80 out:
  81         clk_disable_unprepare(pll_x_clk);
  82         return ret;
  83 }
  84
  85 static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
  86 {
  87         unsigned long rate = freq_table[index].frequency;
  88         int ret = 0;
  89
  90         /*
  91          * Vote on memory bus frequency based on cpu frequency
  92          * This sets the minimum frequency, display or avp may request higher
  93          */
  94         if (rate >= 816000)
  95                 clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
  96         else if (rate >= 456000)
  97                 clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
  98         else
  99                 clk_set_rate(emc_clk, 100000000);  /* emc 50Mhz */
 100
 101         ret = tegra_cpu_clk_set_rate(rate * 1000);
 102         if (ret)
 103                 pr_err("cpu-tegra: Failed to set cpu frequency to %lu kHz\n",
 104                         rate);
 105
 106         return ret;
 107 }
 108
 109 static int tegra_cpu_init(struct cpufreq_policy *policy)
 110 {
 111         int ret;
 112
 113         if (policy->cpu >= NUM_CPUS)
 114                 return -EINVAL;
 115
 116         clk_prepare_enable(emc_clk);
 117         clk_prepare_enable(cpu_clk);
 118
 119         /* FIXME: what's the actual transition time? */
 120         ret = cpufreq_generic_init(policy, freq_table, 300 * 1000);
 121         if (ret) {
 122                 clk_disable_unprepare(cpu_clk);
 123                 clk_disable_unprepare(emc_clk);
 124                 return ret;
 125         }
 126
 127         policy->clk = cpu_clk;
 128         policy->suspend_freq = freq_table[0].frequency;
 129         return 0;
 130 }
 131
 132 static int tegra_cpu_exit(struct cpufreq_policy *policy)
 133 {
 134         clk_disable_unprepare(cpu_clk);
 135         clk_disable_unprepare(emc_clk);
 136         return 0;
 137 }
 138
 139 static struct cpufreq_driver tegra_cpufreq_driver = {
 140         .flags          = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 141         .verify         = cpufreq_generic_frequency_table_verify,
 142         .target_index   = tegra_target,
 143         .get            = cpufreq_generic_get,
 144         .init           = tegra_cpu_init,
 145         .exit           = tegra_cpu_exit,
 146         .name           = "tegra",
 147         .attr           = cpufreq_generic_attr,
 148 #ifdef CONFIG_PM
 149         .suspend        = cpufreq_generic_suspend,
 150 #endif
 151 };
 152
 153 static int __init tegra_cpufreq_init(void)
 154 {
 155         cpu_clk = clk_get_sys(NULL, "cclk");
 156         if (IS_ERR(cpu_clk))
 157                 return PTR_ERR(cpu_clk);
 158
 159         pll_x_clk = clk_get_sys(NULL, "pll_x");
 160         if (IS_ERR(pll_x_clk))
 161                 return PTR_ERR(pll_x_clk);
 162
 163         pll_p_clk = clk_get_sys(NULL, "pll_p");
 164         if (IS_ERR(pll_p_clk))
 165                 return PTR_ERR(pll_p_clk);
 166
 167         emc_clk = clk_get_sys("cpu", "emc");
 168         if (IS_ERR(emc_clk)) {
 169                 clk_put(cpu_clk);
 170                 return PTR_ERR(emc_clk);
 171         }
 172
 173         return cpufreq_register_driver(&tegra_cpufreq_driver);
 174 }
 175
 176 static void __exit tegra_cpufreq_exit(void)
 177 {
 178         cpufreq_unregister_driver(&tegra_cpufreq_driver);
 179         clk_put(emc_clk);
 180         clk_put(cpu_clk);
 181 }
 182
 183
 184 MODULE_AUTHOR("Colin Cross <ccross@android.com>");
 185 MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2");
 186 MODULE_LICENSE("GPL");
 187 module_init(tegra_cpufreq_init);
 188 module_exit(tegra_cpufreq_exit);