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
  32 #include <asm/system.h>
  33
  34 #include <mach/hardware.h>
  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, 312000 },
  40         { 1, 456000 },
  41         { 2, 608000 },
  42         { 3, 760000 },
  43         { 4, 816000 },
  44         { 5, 912000 },
  45         { 6, 1000000 },
  46         { 7, CPUFREQ_TABLE_END },
  47 };
  48
  49 #define NUM_CPUS        2
  50
  51 static struct clk *cpu_clk;
  52
  53 static unsigned long target_cpu_speed[NUM_CPUS];
  54
  55 int tegra_verify_speed(struct cpufreq_policy *policy)
  56 {
  57         return cpufreq_frequency_table_verify(policy, freq_table);
  58 }
  59
  60 unsigned int tegra_getspeed(unsigned int cpu)
  61 {
  62         unsigned long rate;
  63
  64         if (cpu >= NUM_CPUS)
  65                 return 0;
  66
  67         rate = clk_get_rate(cpu_clk) / 1000;
  68         return rate;
  69 }
  70
  71 static int tegra_update_cpu_speed(void)
  72 {
  73         int i;
  74         unsigned long rate = 0;
  75         int ret = 0;
  76         struct cpufreq_freqs freqs;
  77
  78         for_each_online_cpu(i)
  79                 rate = max(rate, target_cpu_speed[i]);
  80
  81         freqs.old = tegra_getspeed(0);
  82         freqs.new = rate;
  83
  84         if (freqs.old == freqs.new)
  85                 return ret;
  86
  87         for_each_online_cpu(freqs.cpu)
  88                 cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  89
  90 #ifdef CONFIG_CPU_FREQ_DEBUG
  91         printk(KERN_DEBUG "cpufreq-tegra: transition: %u --> %u\n",
  92                freqs.old, freqs.new);
  93 #endif
  94
  95         ret = clk_set_rate_cansleep(cpu_clk, freqs.new * 1000);
  96         if (ret) {
  97                 pr_err("cpu-tegra: Failed to set cpu frequency to %d kHz\n",
  98                         freqs.new);
  99                 return ret;
 100         }
 101
 102         for_each_online_cpu(freqs.cpu)
 103                 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
 104
 105         return 0;
 106 }
 107
 108 static int tegra_target(struct cpufreq_policy *policy,
 109                        unsigned int target_freq,
 110                        unsigned int relation)
 111 {
 112         int idx;
 113         unsigned int freq;
 114
 115         cpufreq_frequency_table_target(policy, freq_table, target_freq,
 116                 relation, &idx);
 117
 118         freq = freq_table[idx].frequency;
 119
 120         target_cpu_speed[policy->cpu] = freq;
 121
 122         return tegra_update_cpu_speed();
 123 }
 124
 125 static int tegra_cpu_init(struct cpufreq_policy *policy)
 126 {
 127         if (policy->cpu >= NUM_CPUS)
 128                 return -EINVAL;
 129
 130         cpu_clk = clk_get_sys(NULL, "cpu");
 131         if (IS_ERR(cpu_clk))
 132                 return PTR_ERR(cpu_clk);
 133
 134         cpufreq_frequency_table_cpuinfo(policy, freq_table);
 135         cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 136         policy->cur = tegra_getspeed(policy->cpu);
 137         target_cpu_speed[policy->cpu] = policy->cur;
 138
 139         /* FIXME: what's the actual transition time? */
 140         policy->cpuinfo.transition_latency = 300 * 1000;
 141
 142         policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
 143         cpumask_copy(policy->related_cpus, cpu_possible_mask);
 144
 145         return 0;
 146 }
 147
 148 static int tegra_cpu_exit(struct cpufreq_policy *policy)
 149 {
 150         cpufreq_frequency_table_cpuinfo(policy, freq_table);
 151         clk_put(cpu_clk);
 152         return 0;
 153 }
 154
 155 static struct freq_attr *tegra_cpufreq_attr[] = {
 156         &cpufreq_freq_attr_scaling_available_freqs,
 157         NULL,
 158 };
 159
 160 static struct cpufreq_driver tegra_cpufreq_driver = {
 161         .verify         = tegra_verify_speed,
 162         .target         = tegra_target,
 163         .get            = tegra_getspeed,
 164         .init           = tegra_cpu_init,
 165         .exit           = tegra_cpu_exit,
 166         .name           = "tegra",
 167         .attr           = tegra_cpufreq_attr,
 168 };
 169
 170 static int __init tegra_cpufreq_init(void)
 171 {
 172         return cpufreq_register_driver(&tegra_cpufreq_driver);
 173 }
 174
 175 static void __exit tegra_cpufreq_exit(void)
 176 {
 177         cpufreq_unregister_driver(&tegra_cpufreq_driver);
 178 }
 179
 180
 181 MODULE_AUTHOR("Colin Cross <ccross@android.com>");
 182 MODULE_DESCRIPTION("cpufreq driver for Nvidia Tegra2");
 183 MODULE_LICENSE("GPL");
 184 module_init(tegra_cpufreq_init);
 185 module_exit(tegra_cpufreq_exit);