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 #include <asm/system.h>
  34
  35 #include <mach/clk.h>
  36
  37 /* Frequency table index must be sequential starting at 0 */
  38 static struct cpufreq_frequency_table freq_table[] = {
  39         { 0, 216000 },
  40         { 1, 312000 },
  41         { 2, 456000 },
  42         { 3, 608000 },
  43         { 4, 760000 },
  44         { 5, 816000 },
  45         { 6, 912000 },
  46         { 7, 1000000 },
  47         { 8, CPUFREQ_TABLE_END },
  48 };
  49
  50 #define NUM_CPUS        2
  51
  52 static struct clk *cpu_clk;
  53 static struct clk *emc_clk;
  54
  55 static unsigned long target_cpu_speed[NUM_CPUS];
  56 static DEFINE_MUTEX(tegra_cpu_lock);
  57 static bool is_suspended;
  58
  59 int tegra_verify_speed(struct cpufreq_policy *policy)
  60 {
  61         return cpufreq_frequency_table_verify(policy, freq_table);
  62 }
  63
  64 unsigned int tegra_getspeed(unsigned int cpu)
  65 {
  66         unsigned long rate;
  67
  68         if (cpu >= NUM_CPUS)
  69                 return 0;
  70
  71         rate = clk_get_rate(cpu_clk) / 1000;
  72         return rate;
  73 }
  74
  75 static int tegra_update_cpu_speed(unsigned long rate)
  76 {
  77         int ret = 0;
  78         struct cpufreq_freqs freqs;
  79
  80         freqs.old = tegra_getspeed(0);
  81         freqs.new = rate;
  82
  83         if (freqs.old == freqs.new)
  84                 return ret;
  85
  86         /*
  87          * Vote on memory bus frequency based on cpu frequency
  88          * This sets the minimum frequency, display or avp may request higher
  89          */
  90         if (rate >= 816000)
  91                 clk_set_rate(emc_clk, 600000000); /* cpu 816 MHz, emc max */
  92         else if (rate >= 456000)
  93                 clk_set_rate(emc_clk, 300000000); /* cpu 456 MHz, emc 150Mhz */
  94         else
  95                 clk_set_rate(emc_clk, 100000000);  /* emc 50Mhz */
  96
  97         for_each_online_cpu(freqs.cpu)
  98                 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  99
 100 #ifdef CONFIG_CPU_FREQ_DEBUG
 101         printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n",
 102                freqs.old, freqs.new);
 103 #endif
 104
 105         ret = clk_set_rate(cpu_clk, freqs.new * 1000);
 106         if (ret) {
 107                 pr_err("cpu-tegra: Failed to set cpu frequency to %d kHz\n",
 108                         freqs.new);
 109                 return ret;
 110         }
 111
 112         for_each_online_cpu(freqs.cpu)
 113                 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 114
 115         return 0;
 116 }
 117
 118 static unsigned long tegra_cpu_highest_speed(void)
 119 {
 120         unsigned long rate = 0;
 121         int i;
 122
 123         for_each_online_cpu(i)
 124                 rate = max(rate, target_cpu_speed[i]);
 125         return rate;
 126 }
 127
 128 static int tegra_target(struct cpufreq_policy *policy,
 129                        unsigned int target_freq,
 130                        unsigned int relation)
 131 {
 132         int idx;
 133         unsigned int freq;
 134         int ret = 0;
 135
 136         mutex_lock(&tegra_cpu_lock);
 137
 138         if (is_suspended) {
 139                 ret = -EBUSY;
 140                 goto out;
 141         }
 142
 143         cpufreq_frequency_table_target(policy, freq_table, target_freq,
 144                 relation, &idx);
 145
 146         freq = freq_table[idx].frequency;
 147
 148         target_cpu_speed[policy->cpu] = freq;
 149
 150         ret = tegra_update_cpu_speed(tegra_cpu_highest_speed());
 151
 152 out:
 153         mutex_unlock(&tegra_cpu_lock);
 154         return ret;
 155 }
 156
 157 static int tegra_pm_notify(struct notifier_block *nb, unsigned long event,
 158         void *dummy)
 159 {
 160         mutex_lock(&tegra_cpu_lock);
 161         if (event == PM_SUSPEND_PREPARE) {
 162                 is_suspended = true;
 163                 pr_info("Tegra cpufreq suspend: setting frequency to %d kHz\n",
 164                         freq_table[0].frequency);
 165                 tegra_update_cpu_speed(freq_table[0].frequency);
 166         } else if (event == PM_POST_SUSPEND) {
 167                 is_suspended = false;
 168         }
 169         mutex_unlock(&tegra_cpu_lock);
 170
 171         return NOTIFY_OK;
 172 }
 173
 174 static struct notifier_block tegra_cpu_pm_notifier = {
 175         .notifier_call = tegra_pm_notify,
 176 };
 177
 178 static int tegra_cpu_init(struct cpufreq_policy *policy)
 179 {
 180         if (policy->cpu >= NUM_CPUS)
 181                 return -EINVAL;
 182
 183         cpu_clk = clk_get_sys(NULL, "cpu");
 184         if (IS_ERR(cpu_clk))
 185                 return PTR_ERR(cpu_clk);
 186
 187         emc_clk = clk_get_sys("cpu", "emc");
 188         if (IS_ERR(emc_clk)) {
 189                 clk_put(cpu_clk);
 190                 return PTR_ERR(emc_clk);
 191         }
 192
 193         clk_enable(emc_clk);
 194         clk_enable(cpu_clk);
 195
 196         cpufreq_frequency_table_cpuinfo(policy, freq_table);
 197         cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 198         policy->cur = tegra_getspeed(policy->cpu);
 199         target_cpu_speed[policy->cpu] = policy->cur;
 200
 201         /* FIXME: what's the actual transition time? */
 202         policy->cpuinfo.transition_latency = 300 * 1000;
 203
 204         policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
 205         cpumask_copy(policy->related_cpus, cpu_possible_mask);
 206
 207         if (policy->cpu == 0)
 208                 register_pm_notifier(&tegra_cpu_pm_notifier);
 209
 210         return 0;
 211 }
 212
 213 static int tegra_cpu_exit(struct cpufreq_policy *policy)
 214 {
 215         cpufreq_frequency_table_cpuinfo(policy, freq_table);
 216         clk_disable(emc_clk);
 217         clk_put(emc_clk);
 218         clk_put(cpu_clk);
 219         return 0;
 220 }
 221
 222 static struct freq_attr *tegra_cpufreq_attr[] = {
 223         &cpufreq_freq_attr_scaling_available_freqs,
 224         NULL,
 225 };
 226
 227 static struct cpufreq_driver tegra_cpufreq_driver = {
 228         .verify         = tegra_verify_speed,
 229         .target         = tegra_target,
 230         .get            = tegra_getspeed,
 231         .init           = tegra_cpu_init,
 232         .exit           = tegra_cpu_exit,
 233         .name           = "tegra",
 234         .attr           = tegra_cpufreq_attr,
 235 };
 236
 237 static int __init tegra_cpufreq_init(void)
 238 {
 239         return cpufreq_register_driver(&tegra_cpufreq_driver);
 240 }
 241
 242 static void __exit tegra_cpufreq_exit(void)
 243 {
 244         cpufreq_unregister_driver(&tegra_cpufreq_driver);
 245 }
 246
 247
 248 MODULE_AUTHOR("Colin Cross <ccross@android.com>");
 249 MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2");
 250 MODULE_LICENSE("GPL");
 251 module_init(tegra_cpufreq_init);
 252 module_exit(tegra_cpufreq_exit);