drivers/cpufreq/db8500-cpufreq.c

   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
  18 static 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
  42 static enum arm_opp idx2opp[] = {
  43         ARM_EXTCLK,
  44         ARM_50_OPP,
  45         ARM_100_OPP,
  46         ARM_MAX_OPP
  47 };
  48
  49 static struct freq_attr *db8500_cpufreq_attr[] = {
  50         &cpufreq_freq_attr_scaling_available_freqs,
  51         NULL,
  52 };
  53
  54 static int db8500_cpufreq_verify_speed(struct cpufreq_policy *policy)
  55 {
  56         return cpufreq_frequency_table_verify(policy, freq_table);
  57 }
  58
  59 static 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
 101 static 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
 110 static 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
 152 static 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
 162 static int __init db8500_cpufreq_register(void)
 163 {
 164         if (!cpu_is_u8500v20_or_later())
 165                 return -ENODEV;
 166
 167         pr_info("cpufreq for DB8500 started\n");
 168         return cpufreq_register_driver(&db8500_cpufreq_driver);
 169 }
 170 device_initcall(db8500_cpufreq_register);