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/db8500-prcmu.h>
  16 #include <mach/id.h>
  17
  18 static struct cpufreq_frequency_table freq_table[] = {
  19         [0] = {
  20                 .index = 0,
  21                 .frequency = 300000,
  22         },
  23         [1] = {
  24                 .index = 1,
  25                 .frequency = 600000,
  26         },
  27         [2] = {
  28                 /* Used for MAX_OPP, if available */
  29                 .index = 2,
  30                 .frequency = CPUFREQ_TABLE_END,
  31         },
  32         [3] = {
  33                 .index = 3,
  34                 .frequency = CPUFREQ_TABLE_END,
  35         },
  36 };
  37
  38 static enum arm_opp idx2opp[] = {
  39         ARM_50_OPP,
  40         ARM_100_OPP,
  41         ARM_MAX_OPP
  42 };
  43
  44 static struct freq_attr *db8500_cpufreq_attr[] = {
  45         &cpufreq_freq_attr_scaling_available_freqs,
  46         NULL,
  47 };
  48
  49 static int db8500_cpufreq_verify_speed(struct cpufreq_policy *policy)
  50 {
  51         return cpufreq_frequency_table_verify(policy, freq_table);
  52 }
  53
  54 static int db8500_cpufreq_target(struct cpufreq_policy *policy,
  55                                 unsigned int target_freq,
  56                                 unsigned int relation)
  57 {
  58         struct cpufreq_freqs freqs;
  59         unsigned int idx;
  60
  61         /* scale the target frequency to one of the extremes supported */
  62         if (target_freq < policy->cpuinfo.min_freq)
  63                 target_freq = policy->cpuinfo.min_freq;
  64         if (target_freq > policy->cpuinfo.max_freq)
  65                 target_freq = policy->cpuinfo.max_freq;
  66
  67         /* Lookup the next frequency */
  68         if (cpufreq_frequency_table_target
  69             (policy, freq_table, target_freq, relation, &idx)) {
  70                 return -EINVAL;
  71         }
  72
  73         freqs.old = policy->cur;
  74         freqs.new = freq_table[idx].frequency;
  75         freqs.cpu = policy->cpu;
  76
  77         if (freqs.old == freqs.new)
  78                 return 0;
  79
  80         /* pre-change notification */
  81         cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  82
  83         /* request the PRCM unit for opp change */
  84         if (prcmu_set_arm_opp(idx2opp[idx])) {
  85                 pr_err("db8500-cpufreq:  Failed to set OPP level\n");
  86                 return -EINVAL;
  87         }
  88
  89         /* post change notification */
  90         cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  91
  92         return 0;
  93 }
  94
  95 static unsigned int db8500_cpufreq_getspeed(unsigned int cpu)
  96 {
  97         int i;
  98         /* request the prcm to get the current ARM opp */
  99         for (i = 0; prcmu_get_arm_opp() != idx2opp[i]; i++)
 100                 ;
 101         return freq_table[i].frequency;
 102 }
 103
 104 static int __cpuinit db8500_cpufreq_init(struct cpufreq_policy *policy)
 105 {
 106         int res;
 107         int i;
 108
 109         BUILD_BUG_ON(ARRAY_SIZE(idx2opp) + 1 != ARRAY_SIZE(freq_table));
 110
 111         if (cpu_is_u8500v2() && !prcmu_is_u8400()) {
 112                 freq_table[0].frequency = 400000;
 113                 freq_table[1].frequency = 800000;
 114                 if (prcmu_has_arm_maxopp())
 115                         freq_table[2].frequency = 1000000;
 116         }
 117
 118         /* get policy fields based on the table */
 119         res = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 120         if (!res)
 121                 cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 122         else {
 123                 pr_err("db8500-cpufreq : Failed to read policy table\n");
 124                 return res;
 125         }
 126
 127         policy->min = policy->cpuinfo.min_freq;
 128         policy->max = policy->cpuinfo.max_freq;
 129         policy->cur = db8500_cpufreq_getspeed(policy->cpu);
 130
 131         for (i = 0; freq_table[i].frequency != policy->cur; i++)
 132                 ;
 133
 134         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 135
 136         /*
 137          * FIXME : Need to take time measurement across the target()
 138          *         function with no/some/all drivers in the notification
 139          *         list.
 140          */
 141         policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */
 142
 143         /* policy sharing between dual CPUs */
 144         cpumask_copy(policy->cpus, &cpu_present_map);
 145
 146         policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
 147
 148         return 0;
 149 }
 150
 151 static struct cpufreq_driver db8500_cpufreq_driver = {
 152         .flags  = CPUFREQ_STICKY,
 153         .verify = db8500_cpufreq_verify_speed,
 154         .target = db8500_cpufreq_target,
 155         .get    = db8500_cpufreq_getspeed,
 156         .init   = db8500_cpufreq_init,
 157         .name   = "DB8500",
 158         .attr   = db8500_cpufreq_attr,
 159 };
 160
 161 static int __init db8500_cpufreq_register(void)
 162 {
 163         if (!cpu_is_u8500v20_or_later())
 164                 return -ENODEV;
 165
 166         pr_info("cpufreq for DB8500 started\n");
 167         return cpufreq_register_driver(&db8500_cpufreq_driver);
 168 }
 169 device_initcall(db8500_cpufreq_register);