arch/arm/mach-tegra/cpu-tegra.c

   1 /*
   2  * arch/arm/mach-tegra/cpu-tegra.c
   3  *
   4  * Copyright (C) 2010 Google, Inc.
   5  *
   6  * Author:
   7  *      Colin Cross <ccross@google.com>
   8  *      Based on arch/arm/plat-omap/cpu-omap.c, (C) 2005 Nokia Corporation
   9  *
  10  * This software is licensed under the terms of the GNU General Public
  11  * License version 2, as published by the Free Software Foundation, and
  12  * may be copied, distributed, and modified under those terms.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  *
  19  */
  20
  21 #include <linux/kernel.h>
  22 #include <linux/module.h>
  23 #include <linux/types.h>
  24 #include <linux/sched.h>
  25 #include <linux/cpufreq.h>
  26 #include <linux/delay.h>
  27 #include <linux/init.h>
  28 #include <linux/err.h>
  29 #include <linux/clk.h>
  30 #include <linux/io.h>
  31 #include <linux/suspend.h>
  32
  33
  34 #include <mach/clk.h>
  35
  36 /* Frequency table index must be sequential starting at 0 */
  37 static struct cpufreq_frequency_table freq_table[] = {
  38         { 0, 216000 },
  39         { 1, 312000 },
  40         { 2, 456000 },
  41         { 3, 608000 },
  42         { 4, 760000 },
  43         { 5, 816000 },
  44         { 6, 912000 },
  45         { 7, 1000000 },
  46         { 8, CPUFREQ_TABLE_END },
  47 };
  48
  49 #define NUM_CPUS        2
  50
  51 static struct clk *cpu_clk;
  52 static struct clk *emc_clk;
  53
  54 static unsigned long target_cpu_speed[NUM_CPUS];
  55 static DEFINE_MUTEX(tegra_cpu_lock);
  56 static bool is_suspended;
  57
  58 static int tegra_verify_speed(struct cpufreq_policy *policy)
  59 {
  60         return cpufreq_frequency_table_verify(policy, freq_table);
  61 }
  62
  63 static unsigned int tegra_getspeed(unsigned int cpu)
  64 {
  65         unsigned long rate;
  66
  67         if (cpu >= NUM_CPUS)
  68                 return 0;
  69
  70         rate = clk_get_rate(cpu_clk) / 1000;
  71         return rate;
  72 }
  73
  74 static int tegra_update_cpu_speed(unsigned long rate)
  75 {
  76         int ret = 0;
  77         struct cpufreq_freqs freqs;
  78
  79         freqs.old = tegra_getspeed(0);
  80         freqs.new = rate;
  81
  82         if (freqs.old == freqs.new)
  83                 return ret;
  84
  85         /*
  86          * Vote on memory bus frequency based on cpu frequency
  87          * This sets the minimum frequency, display or avp may request higher
  88          */
  89         if (rate >= 816000)
  90                 clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
  91         else if (rate >= 456000)
  92                 clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
  93         else
  94                 clk_set_rate(emc_clk, 100000000);  /* emc 50Mhz */
  95
  96         for_each_online_cpu(freqs.cpu)
  97                 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  98
  99 #ifdef CONFIG_CPU_FREQ_DEBUG
 100         printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n",
 101                freqs.old, freqs.new);
 102 #endif
 103
 104         ret = clk_set_rate(cpu_clk, freqs.new * 1000);
 105         if (ret) {
 106                 pr_err("cpu-tegra: Failed to set cpu frequency to %d kHz\n",
 107                         freqs.new);
 108                 return ret;
 109         }
 110
 111         for_each_online_cpu(freqs.cpu)
 112                 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 113
 114         return 0;
 115 }
 116
 117 static unsigned long tegra_cpu_highest_speed(void)
 118 {
 119         unsigned long rate = 0;
 120         int i;
 121
 122         for_each_online_cpu(i)
 123                 rate = max(rate, target_cpu_speed[i]);
 124         return rate;
 125 }
 126
 127 static int tegra_target(struct cpufreq_policy *policy,
 128                        unsigned int target_freq,
 129                        unsigned int relation)
 130 {
 131         unsigned int idx;
 132         unsigned int freq;
 133         int ret = 0;
 134
 135         mutex_lock(&tegra_cpu_lock);
 136
 137         if (is_suspended) {
 138                 ret = -EBUSY;
 139                 goto out;
 140         }
 141
 142         cpufreq_frequency_table_target(policy, freq_table, target_freq,
 143                 relation, &idx);
 144
 145         freq = freq_table[idx].frequency;
 146
 147         target_cpu_speed[policy->cpu] = freq;
 148
 149         ret = tegra_update_cpu_speed(tegra_cpu_highest_speed());
 150
 151 out:
 152         mutex_unlock(&tegra_cpu_lock);
 153         return ret;
 154 }
 155
 156 static int tegra_pm_notify(struct notifier_block *nb, unsigned long event,
 157         void *dummy)
 158 {
 159         mutex_lock(&tegra_cpu_lock);
 160         if (event == PM_SUSPEND_PREPARE) {
 161                 is_suspended = true;
 162                 pr_info("Tegra cpufreq suspend: setting frequency to %d kHz\n",
 163                         freq_table[0].frequency);
 164                 tegra_update_cpu_speed(freq_table[0].frequency);
 165         } else if (event == PM_POST_SUSPEND) {
 166                 is_suspended = false;
 167         }
 168         mutex_unlock(&tegra_cpu_lock);
 169
 170         return NOTIFY_OK;
 171 }
 172
 173 static struct notifier_block tegra_cpu_pm_notifier = {
 174         .notifier_call = tegra_pm_notify,
 175 };
 176
 177 static int tegra_cpu_init(struct cpufreq_policy *policy)
 178 {
 179         if (policy->cpu >= NUM_CPUS)
 180                 return -EINVAL;
 181
 182         cpu_clk = clk_get_sys(NULL, "cpu");
 183         if (IS_ERR(cpu_clk))
 184                 return PTR_ERR(cpu_clk);
 185
 186         emc_clk = clk_get_sys("cpu", "emc");
 187         if (IS_ERR(emc_clk)) {
 188                 clk_put(cpu_clk);
 189                 return PTR_ERR(emc_clk);
 190         }
 191
 192         clk_prepare_enable(emc_clk);
 193         clk_prepare_enable(cpu_clk);
 194
 195         cpufreq_frequency_table_cpuinfo(policy, freq_table);
 196         cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 197         policy->cur = tegra_getspeed(policy->cpu);
 198         target_cpu_speed[policy->cpu] = policy->cur;
 199
 200         /* FIXME: what's the actual transition time? */
 201         policy->cpuinfo.transition_latency = 300 * 1000;
 202
 203         policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
 204         cpumask_copy(policy->related_cpus, cpu_possible_mask);
 205
 206         if (policy->cpu == 0)
 207                 register_pm_notifier(&tegra_cpu_pm_notifier);
 208
 209         return 0;
 210 }
 211
 212 static int tegra_cpu_exit(struct cpufreq_policy *policy)
 213 {
 214         cpufreq_frequency_table_cpuinfo(policy, freq_table);
 215         clk_disable_unprepare(emc_clk);
 216         clk_put(emc_clk);
 217         clk_put(cpu_clk);
 218         return 0;
 219 }
 220
 221 static struct freq_attr *tegra_cpufreq_attr[] = {
 222         &cpufreq_freq_attr_scaling_available_freqs,
 223         NULL,
 224 };
 225
 226 static struct cpufreq_driver tegra_cpufreq_driver = {
 227         .verify         = tegra_verify_speed,
 228         .target         = tegra_target,
 229         .get            = tegra_getspeed,
 230         .init           = tegra_cpu_init,
 231         .exit           = tegra_cpu_exit,
 232         .name           = "tegra",
 233         .attr           = tegra_cpufreq_attr,
 234 };
 235
 236 static int __init tegra_cpufreq_init(void)
 237 {
 238         return cpufreq_register_driver(&tegra_cpufreq_driver);
 239 }
 240
 241 static void __exit tegra_cpufreq_exit(void)
 242 {
 243         cpufreq_unregister_driver(&tegra_cpufreq_driver);
 244 }
 245
 246
 247 MODULE_AUTHOR("Colin Cross <ccross@android.com>");
 248 MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2");
 249 MODULE_LICENSE("GPL");
 250 module_init(tegra_cpufreq_init);
 251 module_exit(tegra_cpufreq_exit);