linux/drivers/cpufreq/db8500-cpufreq.c
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   1/*
   2 * Copyright (C) STMicroelectronics 2009
   3 * Copyright (C) ST-Ericsson SA 2010
   4 *
   5 * License Terms: GNU General Public License v2
   6 * Author: Sundar Iyer <sundar.iyer@stericsson.com>
   7 * Author: Martin Persson <martin.persson@stericsson.com>
   8 * Author: Jonas Aaberg <jonas.aberg@stericsson.com>
   9 *
  10 */
  11#include <linux/kernel.h>
  12#include <linux/cpufreq.h>
  13#include <linux/delay.h>
  14#include <linux/slab.h>
  15#include <linux/mfd/dbx500-prcmu.h>
  16#include <mach/id.h>
  17
  18static struct cpufreq_frequency_table freq_table[] = {
  19        [0] = {
  20                .index = 0,
  21                .frequency = 200000,
  22        },
  23        [1] = {
  24                .index = 1,
  25                .frequency = 400000,
  26        },
  27        [2] = {
  28                .index = 2,
  29                .frequency = 800000,
  30        },
  31        [3] = {
  32                /* Used for MAX_OPP, if available */
  33                .index = 3,
  34                .frequency = CPUFREQ_TABLE_END,
  35        },
  36        [4] = {
  37                .index = 4,
  38                .frequency = CPUFREQ_TABLE_END,
  39        },
  40};
  41
  42static enum arm_opp idx2opp[] = {
  43        ARM_EXTCLK,
  44        ARM_50_OPP,
  45        ARM_100_OPP,
  46        ARM_MAX_OPP
  47};
  48
  49static struct freq_attr *db8500_cpufreq_attr[] = {
  50        &cpufreq_freq_attr_scaling_available_freqs,
  51        NULL,
  52};
  53
  54static int db8500_cpufreq_verify_speed(struct cpufreq_policy *policy)
  55{
  56        return cpufreq_frequency_table_verify(policy, freq_table);
  57}
  58
  59static int db8500_cpufreq_target(struct cpufreq_policy *policy,
  60                                unsigned int target_freq,
  61                                unsigned int relation)
  62{
  63        struct cpufreq_freqs freqs;
  64        unsigned int idx;
  65
  66        /* scale the target frequency to one of the extremes supported */
  67        if (target_freq < policy->cpuinfo.min_freq)
  68                target_freq = policy->cpuinfo.min_freq;
  69        if (target_freq > policy->cpuinfo.max_freq)
  70                target_freq = policy->cpuinfo.max_freq;
  71
  72        /* Lookup the next frequency */
  73        if (cpufreq_frequency_table_target
  74            (policy, freq_table, target_freq, relation, &idx)) {
  75                return -EINVAL;
  76        }
  77
  78        freqs.old = policy->cur;
  79        freqs.new = freq_table[idx].frequency;
  80
  81        if (freqs.old == freqs.new)
  82                return 0;
  83
  84        /* pre-change notification */
  85        for_each_cpu(freqs.cpu, policy->cpus)
  86                cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  87
  88        /* request the PRCM unit for opp change */
  89        if (prcmu_set_arm_opp(idx2opp[idx])) {
  90                pr_err("db8500-cpufreq:  Failed to set OPP level\n");
  91                return -EINVAL;
  92        }
  93
  94        /* post change notification */
  95        for_each_cpu(freqs.cpu, policy->cpus)
  96                cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  97
  98        return 0;
  99}
 100
 101static unsigned int db8500_cpufreq_getspeed(unsigned int cpu)
 102{
 103        int i;
 104        /* request the prcm to get the current ARM opp */
 105        for (i = 0; prcmu_get_arm_opp() != idx2opp[i]; i++)
 106                ;
 107        return freq_table[i].frequency;
 108}
 109
 110static int __cpuinit db8500_cpufreq_init(struct cpufreq_policy *policy)
 111{
 112        int i, res;
 113
 114        BUILD_BUG_ON(ARRAY_SIZE(idx2opp) + 1 != ARRAY_SIZE(freq_table));
 115
 116        if (prcmu_has_arm_maxopp())
 117                freq_table[3].frequency = 1000000;
 118
 119        pr_info("db8500-cpufreq : Available frequencies:\n");
 120        for (i = 0; freq_table[i].frequency != CPUFREQ_TABLE_END; i++)
 121                pr_info("  %d Mhz\n", freq_table[i].frequency/1000);
 122
 123        /* get policy fields based on the table */
 124        res = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 125        if (!res)
 126                cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 127        else {
 128                pr_err("db8500-cpufreq : Failed to read policy table\n");
 129                return res;
 130        }
 131
 132        policy->min = policy->cpuinfo.min_freq;
 133        policy->max = policy->cpuinfo.max_freq;
 134        policy->cur = db8500_cpufreq_getspeed(policy->cpu);
 135        policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 136
 137        /*
 138         * FIXME : Need to take time measurement across the target()
 139         *         function with no/some/all drivers in the notification
 140         *         list.
 141         */
 142        policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */
 143
 144        /* policy sharing between dual CPUs */
 145        cpumask_copy(policy->cpus, cpu_present_mask);
 146
 147        policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
 148
 149        return 0;
 150}
 151
 152static struct cpufreq_driver db8500_cpufreq_driver = {
 153        .flags  = CPUFREQ_STICKY,
 154        .verify = db8500_cpufreq_verify_speed,
 155        .target = db8500_cpufreq_target,
 156        .get    = db8500_cpufreq_getspeed,
 157        .init   = db8500_cpufreq_init,
 158        .name   = "DB8500",
 159        .attr   = db8500_cpufreq_attr,
 160};
 161
 162static int __init db8500_cpufreq_register(void)
 163{
 164        if (!cpu_is_u8500_family())
 165                return -ENODEV;
 166
 167        pr_info("cpufreq for DB8500 started\n");
 168        return cpufreq_register_driver(&db8500_cpufreq_driver);
 169}
 170device_initcall(db8500_cpufreq_register);
 171
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