linux/drivers/cpufreq/dbx500-cpufreq.c
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   1/*
   2 * Copyright (C) STMicroelectronics 2009
   3 * Copyright (C) ST-Ericsson SA 2010-2012
   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/module.h>
  12#include <linux/kernel.h>
  13#include <linux/cpufreq.h>
  14#include <linux/delay.h>
  15#include <linux/slab.h>
  16#include <linux/platform_device.h>
  17#include <linux/clk.h>
  18
  19static struct cpufreq_frequency_table *freq_table;
  20static struct clk *armss_clk;
  21
  22static struct freq_attr *dbx500_cpufreq_attr[] = {
  23        &cpufreq_freq_attr_scaling_available_freqs,
  24        NULL,
  25};
  26
  27static int dbx500_cpufreq_verify_speed(struct cpufreq_policy *policy)
  28{
  29        return cpufreq_frequency_table_verify(policy, freq_table);
  30}
  31
  32static int dbx500_cpufreq_target(struct cpufreq_policy *policy,
  33                                unsigned int target_freq,
  34                                unsigned int relation)
  35{
  36        struct cpufreq_freqs freqs;
  37        unsigned int idx;
  38        int ret;
  39
  40        /* scale the target frequency to one of the extremes supported */
  41        if (target_freq < policy->cpuinfo.min_freq)
  42                target_freq = policy->cpuinfo.min_freq;
  43        if (target_freq > policy->cpuinfo.max_freq)
  44                target_freq = policy->cpuinfo.max_freq;
  45
  46        /* Lookup the next frequency */
  47        if (cpufreq_frequency_table_target(policy, freq_table, target_freq,
  48                                        relation, &idx))
  49                return -EINVAL;
  50
  51        freqs.old = policy->cur;
  52        freqs.new = freq_table[idx].frequency;
  53
  54        if (freqs.old == freqs.new)
  55                return 0;
  56
  57        /* pre-change notification */
  58        for_each_cpu(freqs.cpu, policy->cpus)
  59                cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  60
  61        /* update armss clk frequency */
  62        ret = clk_set_rate(armss_clk, freqs.new * 1000);
  63
  64        if (ret) {
  65                pr_err("dbx500-cpufreq: Failed to set armss_clk to %d Hz: error %d\n",
  66                       freqs.new * 1000, ret);
  67                return ret;
  68        }
  69
  70        /* post change notification */
  71        for_each_cpu(freqs.cpu, policy->cpus)
  72                cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  73
  74        return 0;
  75}
  76
  77static unsigned int dbx500_cpufreq_getspeed(unsigned int cpu)
  78{
  79        int i = 0;
  80        unsigned long freq = clk_get_rate(armss_clk) / 1000;
  81
  82        while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
  83                if (freq <= freq_table[i].frequency)
  84                        return freq_table[i].frequency;
  85                i++;
  86        }
  87
  88        /* We could not find a corresponding frequency. */
  89        pr_err("dbx500-cpufreq: Failed to find cpufreq speed\n");
  90        return 0;
  91}
  92
  93static int __cpuinit dbx500_cpufreq_init(struct cpufreq_policy *policy)
  94{
  95        int res;
  96
  97        /* get policy fields based on the table */
  98        res = cpufreq_frequency_table_cpuinfo(policy, freq_table);
  99        if (!res)
 100                cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 101        else {
 102                pr_err("dbx500-cpufreq: Failed to read policy table\n");
 103                return res;
 104        }
 105
 106        policy->min = policy->cpuinfo.min_freq;
 107        policy->max = policy->cpuinfo.max_freq;
 108        policy->cur = dbx500_cpufreq_getspeed(policy->cpu);
 109        policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 110
 111        /*
 112         * FIXME : Need to take time measurement across the target()
 113         *         function with no/some/all drivers in the notification
 114         *         list.
 115         */
 116        policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */
 117
 118        /* policy sharing between dual CPUs */
 119        cpumask_setall(policy->cpus);
 120
 121        return 0;
 122}
 123
 124static struct cpufreq_driver dbx500_cpufreq_driver = {
 125        .flags  = CPUFREQ_STICKY | CPUFREQ_CONST_LOOPS,
 126        .verify = dbx500_cpufreq_verify_speed,
 127        .target = dbx500_cpufreq_target,
 128        .get    = dbx500_cpufreq_getspeed,
 129        .init   = dbx500_cpufreq_init,
 130        .name   = "DBX500",
 131        .attr   = dbx500_cpufreq_attr,
 132};
 133
 134static int dbx500_cpufreq_probe(struct platform_device *pdev)
 135{
 136        int i = 0;
 137
 138        freq_table = dev_get_platdata(&pdev->dev);
 139        if (!freq_table) {
 140                pr_err("dbx500-cpufreq: Failed to fetch cpufreq table\n");
 141                return -ENODEV;
 142        }
 143
 144        armss_clk = clk_get(&pdev->dev, "armss");
 145        if (IS_ERR(armss_clk)) {
 146                pr_err("dbx500-cpufreq: Failed to get armss clk\n");
 147                return PTR_ERR(armss_clk);
 148        }
 149
 150        pr_info("dbx500-cpufreq: Available frequencies:\n");
 151        while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
 152                pr_info("  %d Mhz\n", freq_table[i].frequency/1000);
 153                i++;
 154        }
 155
 156        return cpufreq_register_driver(&dbx500_cpufreq_driver);
 157}
 158
 159static struct platform_driver dbx500_cpufreq_plat_driver = {
 160        .driver = {
 161                .name = "cpufreq-ux500",
 162                .owner = THIS_MODULE,
 163        },
 164        .probe = dbx500_cpufreq_probe,
 165};
 166
 167static int __init dbx500_cpufreq_register(void)
 168{
 169        return platform_driver_register(&dbx500_cpufreq_plat_driver);
 170}
 171device_initcall(dbx500_cpufreq_register);
 172
 173MODULE_LICENSE("GPL v2");
 174MODULE_DESCRIPTION("cpufreq driver for DBX500");
 175
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