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 #include <linux/suspend.h>
  30
  31 static struct cpufreq_frequency_table freq_table[] = {
  32         { .frequency = 216000 },
  33         { .frequency = 312000 },
  34         { .frequency = 456000 },
  35         { .frequency = 608000 },
  36         { .frequency = 760000 },
  37         { .frequency = 816000 },
  38         { .frequency = 912000 },
  39         { .frequency = 1000000 },
  40         { .frequency = CPUFREQ_TABLE_END },
  41 };
  42
  43 #define NUM_CPUS        2
  44
  45 static struct clk *cpu_clk;
  46 static struct clk *pll_x_clk;
  47 static struct clk *pll_p_clk;
  48 static struct clk *emc_clk;
  49
  50 static DEFINE_MUTEX(tegra_cpu_lock);
  51 static bool is_suspended;
  52
  53 static int tegra_cpu_clk_set_rate(unsigned long rate)
  54 {
  55         int ret;
  56
  57         /*
  58          * Take an extra reference to the main pll so it doesn't turn
  59          * off when we move the cpu off of it
  60          */
  61         clk_prepare_enable(pll_x_clk);
  62
  63         ret = clk_set_parent(cpu_clk, pll_p_clk);
  64         if (ret) {
  65                 pr_err("Failed to switch cpu to clock pll_p\n");
  66                 goto out;
  67         }
  68
  69         if (rate == clk_get_rate(pll_p_clk))
  70                 goto out;
  71
  72         ret = clk_set_rate(pll_x_clk, rate);
  73         if (ret) {
  74                 pr_err("Failed to change pll_x to %lu\n", rate);
  75                 goto out;
  76         }
  77
  78         ret = clk_set_parent(cpu_clk, pll_x_clk);
  79         if (ret) {
  80                 pr_err("Failed to switch cpu to clock pll_x\n");
  81                 goto out;
  82         }
  83
  84 out:
  85         clk_disable_unprepare(pll_x_clk);
  86         return ret;
  87 }
  88
  89 static int tegra_update_cpu_speed(struct cpufreq_policy *policy,
  90                 unsigned long rate)
  91 {
  92         int ret = 0;
  93
  94         /*
  95          * Vote on memory bus frequency based on cpu frequency
  96          * This sets the minimum frequency, display or avp may request higher
  97          */
  98         if (rate >= 816000)
  99                 clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
 100         else if (rate >= 456000)
 101                 clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
 102         else
 103                 clk_set_rate(emc_clk, 100000000);  /* emc 50Mhz */
 104
 105         ret = tegra_cpu_clk_set_rate(rate * 1000);
 106         if (ret)
 107                 pr_err("cpu-tegra: Failed to set cpu frequency to %lu kHz\n",
 108                         rate);
 109
 110         return ret;
 111 }
 112
 113 static int tegra_target(struct cpufreq_policy *policy, unsigned int index)
 114 {
 115         int ret = -EBUSY;
 116
 117         mutex_lock(&tegra_cpu_lock);
 118
 119         if (!is_suspended)
 120                 ret = tegra_update_cpu_speed(policy,
 121                                 freq_table[index].frequency);
 122
 123         mutex_unlock(&tegra_cpu_lock);
 124         return ret;
 125 }
 126
 127 static int tegra_pm_notify(struct notifier_block *nb, unsigned long event,
 128         void *dummy)
 129 {
 130         mutex_lock(&tegra_cpu_lock);
 131         if (event == PM_SUSPEND_PREPARE) {
 132                 struct cpufreq_policy *policy = cpufreq_cpu_get(0);
 133                 is_suspended = true;
 134                 pr_info("Tegra cpufreq suspend: setting frequency to %d kHz\n",
 135                         freq_table[0].frequency);
 136                 if (clk_get_rate(cpu_clk) / 1000 != freq_table[0].frequency)
 137                         tegra_update_cpu_speed(policy, freq_table[0].frequency);
 138                 cpufreq_cpu_put(policy);
 139         } else if (event == PM_POST_SUSPEND) {
 140                 is_suspended = false;
 141         }
 142         mutex_unlock(&tegra_cpu_lock);
 143
 144         return NOTIFY_OK;
 145 }
 146
 147 static struct notifier_block tegra_cpu_pm_notifier = {
 148         .notifier_call = tegra_pm_notify,
 149 };
 150
 151 static int tegra_cpu_init(struct cpufreq_policy *policy)
 152 {
 153         int ret;
 154
 155         if (policy->cpu >= NUM_CPUS)
 156                 return -EINVAL;
 157
 158         clk_prepare_enable(emc_clk);
 159         clk_prepare_enable(cpu_clk);
 160
 161         /* FIXME: what's the actual transition time? */
 162         ret = cpufreq_generic_init(policy, freq_table, 300 * 1000);
 163         if (ret) {
 164                 clk_disable_unprepare(cpu_clk);
 165                 clk_disable_unprepare(emc_clk);
 166                 return ret;
 167         }
 168
 169         if (policy->cpu == 0)
 170                 register_pm_notifier(&tegra_cpu_pm_notifier);
 171
 172         policy->clk = cpu_clk;
 173         return 0;
 174 }
 175
 176 static int tegra_cpu_exit(struct cpufreq_policy *policy)
 177 {
 178         cpufreq_frequency_table_put_attr(policy->cpu);
 179         clk_disable_unprepare(cpu_clk);
 180         clk_disable_unprepare(emc_clk);
 181         return 0;
 182 }
 183
 184 static struct cpufreq_driver tegra_cpufreq_driver = {
 185         .flags          = CPUFREQ_NEED_INITIAL_FREQ_CHECK,
 186         .verify         = cpufreq_generic_frequency_table_verify,
 187         .target_index   = tegra_target,
 188         .get            = cpufreq_generic_get,
 189         .init           = tegra_cpu_init,
 190         .exit           = tegra_cpu_exit,
 191         .name           = "tegra",
 192         .attr           = cpufreq_generic_attr,
 193 };
 194
 195 static int __init tegra_cpufreq_init(void)
 196 {
 197         cpu_clk = clk_get_sys(NULL, "cclk");
 198         if (IS_ERR(cpu_clk))
 199                 return PTR_ERR(cpu_clk);
 200
 201         pll_x_clk = clk_get_sys(NULL, "pll_x");
 202         if (IS_ERR(pll_x_clk))
 203                 return PTR_ERR(pll_x_clk);
 204
 205         pll_p_clk = clk_get_sys(NULL, "pll_p");
 206         if (IS_ERR(pll_p_clk))
 207                 return PTR_ERR(pll_p_clk);
 208
 209         emc_clk = clk_get_sys("cpu", "emc");
 210         if (IS_ERR(emc_clk)) {
 211                 clk_put(cpu_clk);
 212                 return PTR_ERR(emc_clk);
 213         }
 214
 215         return cpufreq_register_driver(&tegra_cpufreq_driver);
 216 }
 217
 218 static void __exit tegra_cpufreq_exit(void)
 219 {
 220         cpufreq_unregister_driver(&tegra_cpufreq_driver);
 221         clk_put(emc_clk);
 222         clk_put(cpu_clk);
 223 }
 224
 225
 226 MODULE_AUTHOR("Colin Cross <ccross@android.com>");
 227 MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2");
 228 MODULE_LICENSE("GPL");
 229 module_init(tegra_cpufreq_init);
 230 module_exit(tegra_cpufreq_exit);