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/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#include <mach/id.h>
  19
  20static struct cpufreq_frequency_table *freq_table;
  21static struct clk *armss_clk;
  22
  23static struct freq_attr *db8500_cpufreq_attr[] = {
  24        &cpufreq_freq_attr_scaling_available_freqs,
  25        NULL,
  26};
  27
  28static int db8500_cpufreq_verify_speed(struct cpufreq_policy *policy)
  29{
  30        return cpufreq_frequency_table_verify(policy, freq_table);
  31}
  32
  33static int db8500_cpufreq_target(struct cpufreq_policy *policy,
  34                                unsigned int target_freq,
  35                                unsigned int relation)
  36{
  37        struct cpufreq_freqs freqs;
  38        unsigned int idx;
  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
  48            (policy, freq_table, target_freq, relation, &idx)) {
  49                return -EINVAL;
  50        }
  51
  52        freqs.old = policy->cur;
  53        freqs.new = freq_table[idx].frequency;
  54
  55        if (freqs.old == freqs.new)
  56                return 0;
  57
  58        /* pre-change notification */
  59        for_each_cpu(freqs.cpu, policy->cpus)
  60                cpufreq_notify_transition(&freqs, CPUFREQ_PRECHANGE);
  61
  62        /* update armss clk frequency */
  63        if (clk_set_rate(armss_clk, freq_table[idx].frequency * 1000)) {
  64                pr_err("db8500-cpufreq: Failed to update armss clk\n");
  65                return -EINVAL;
  66        }
  67
  68        /* post change notification */
  69        for_each_cpu(freqs.cpu, policy->cpus)
  70                cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  71
  72        return 0;
  73}
  74
  75static unsigned int db8500_cpufreq_getspeed(unsigned int cpu)
  76{
  77        int i = 0;
  78        unsigned long freq = clk_get_rate(armss_clk) / 1000;
  79
  80        while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
  81                if (freq <= freq_table[i].frequency)
  82                        return freq_table[i].frequency;
  83                i++;
  84        }
  85
  86        /* We could not find a corresponding frequency. */
  87        pr_err("db8500-cpufreq: Failed to find cpufreq speed\n");
  88        return 0;
  89}
  90
  91static int __cpuinit db8500_cpufreq_init(struct cpufreq_policy *policy)
  92{
  93        int i = 0;
  94        int res;
  95
  96        armss_clk = clk_get(NULL, "armss");
  97        if (IS_ERR(armss_clk)) {
  98                pr_err("db8500-cpufreq : Failed to get armss clk\n");
  99                return PTR_ERR(armss_clk);
 100        }
 101
 102        pr_info("db8500-cpufreq : Available frequencies:\n");
 103        while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
 104                pr_info("  %d Mhz\n", freq_table[i].frequency/1000);
 105                i++;
 106        }
 107
 108        /* get policy fields based on the table */
 109        res = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 110        if (!res)
 111                cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 112        else {
 113                pr_err("db8500-cpufreq : Failed to read policy table\n");
 114                clk_put(armss_clk);
 115                return res;
 116        }
 117
 118        policy->min = policy->cpuinfo.min_freq;
 119        policy->max = policy->cpuinfo.max_freq;
 120        policy->cur = db8500_cpufreq_getspeed(policy->cpu);
 121        policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 122
 123        /*
 124         * FIXME : Need to take time measurement across the target()
 125         *         function with no/some/all drivers in the notification
 126         *         list.
 127         */
 128        policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */
 129
 130        /* policy sharing between dual CPUs */
 131        cpumask_copy(policy->cpus, cpu_present_mask);
 132
 133        policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
 134
 135        return 0;
 136}
 137
 138static struct cpufreq_driver db8500_cpufreq_driver = {
 139        .flags  = CPUFREQ_STICKY,
 140        .verify = db8500_cpufreq_verify_speed,
 141        .target = db8500_cpufreq_target,
 142        .get    = db8500_cpufreq_getspeed,
 143        .init   = db8500_cpufreq_init,
 144        .name   = "DB8500",
 145        .attr   = db8500_cpufreq_attr,
 146};
 147
 148static int db8500_cpufreq_probe(struct platform_device *pdev)
 149{
 150        freq_table = dev_get_platdata(&pdev->dev);
 151
 152        if (!freq_table) {
 153                pr_err("db8500-cpufreq: Failed to fetch cpufreq table\n");
 154                return -ENODEV;
 155        }
 156
 157        return cpufreq_register_driver(&db8500_cpufreq_driver);
 158}
 159
 160static struct platform_driver db8500_cpufreq_plat_driver = {
 161        .driver = {
 162                .name = "cpufreq-u8500",
 163                .owner = THIS_MODULE,
 164        },
 165        .probe = db8500_cpufreq_probe,
 166};
 167
 168static int __init db8500_cpufreq_register(void)
 169{
 170        if (!cpu_is_u8500_family())
 171                return -ENODEV;
 172
 173        pr_info("cpufreq for DB8500 started\n");
 174        return platform_driver_register(&db8500_cpufreq_plat_driver);
 175}
 176device_initcall(db8500_cpufreq_register);
 177
 178MODULE_LICENSE("GPL v2");
 179MODULE_DESCRIPTION("cpufreq driver for DB8500");
 180
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