drivers/cpufreq/dbx500-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/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
  20 static struct cpufreq_frequency_table *freq_table;
  21 static struct clk *armss_clk;
  22
  23 static struct freq_attr *dbx500_cpufreq_attr[] = {
  24         &cpufreq_freq_attr_scaling_available_freqs,
  25         NULL,
  26 };
  27
  28 static int dbx500_cpufreq_verify_speed(struct cpufreq_policy *policy)
  29 {
  30         return cpufreq_frequency_table_verify(policy, freq_table);
  31 }
  32
  33 static int dbx500_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         int ret;
  40
  41         /* scale the target frequency to one of the extremes supported */
  42         if (target_freq < policy->cpuinfo.min_freq)
  43                 target_freq = policy->cpuinfo.min_freq;
  44         if (target_freq > policy->cpuinfo.max_freq)
  45                 target_freq = policy->cpuinfo.max_freq;
  46
  47         /* Lookup the next frequency */
  48         if (cpufreq_frequency_table_target(policy, freq_table, target_freq,
  49                                         relation, &idx))
  50                 return -EINVAL;
  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         ret = clk_set_rate(armss_clk, freqs.new * 1000);
  64
  65         if (ret) {
  66                 pr_err("dbx500-cpufreq: Failed to set armss_clk to %d Hz: error %d\n",
  67                        freqs.new * 1000, ret);
  68                 return ret;
  69         }
  70
  71         /* post change notification */
  72         for_each_cpu(freqs.cpu, policy->cpus)
  73                 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  74
  75         return 0;
  76 }
  77
  78 static unsigned int dbx500_cpufreq_getspeed(unsigned int cpu)
  79 {
  80         int i = 0;
  81         unsigned long freq = clk_get_rate(armss_clk) / 1000;
  82
  83         while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
  84                 if (freq <= freq_table[i].frequency)
  85                         return freq_table[i].frequency;
  86                 i++;
  87         }
  88
  89         /* We could not find a corresponding frequency. */
  90         pr_err("dbx500-cpufreq: Failed to find cpufreq speed\n");
  91         return 0;
  92 }
  93
  94 static int __cpuinit dbx500_cpufreq_init(struct cpufreq_policy *policy)
  95 {
  96         int res;
  97
  98         /* get policy fields based on the table */
  99         res = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 100         if (!res)
 101                 cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 102         else {
 103                 pr_err("dbx500-cpufreq: Failed to read policy table\n");
 104                 return res;
 105         }
 106
 107         policy->min = policy->cpuinfo.min_freq;
 108         policy->max = policy->cpuinfo.max_freq;
 109         policy->cur = dbx500_cpufreq_getspeed(policy->cpu);
 110         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 111
 112         /*
 113          * FIXME : Need to take time measurement across the target()
 114          *         function with no/some/all drivers in the notification
 115          *         list.
 116          */
 117         policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */
 118
 119         /* policy sharing between dual CPUs */
 120         cpumask_copy(policy->cpus, cpu_present_mask);
 121
 122         policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
 123
 124         return 0;
 125 }
 126
 127 static struct cpufreq_driver dbx500_cpufreq_driver = {
 128         .flags  = CPUFREQ_STICKY,
 129         .verify = dbx500_cpufreq_verify_speed,
 130         .target = dbx500_cpufreq_target,
 131         .get    = dbx500_cpufreq_getspeed,
 132         .init   = dbx500_cpufreq_init,
 133         .name   = "DBX500",
 134         .attr   = dbx500_cpufreq_attr,
 135 };
 136
 137 static int dbx500_cpufreq_probe(struct platform_device *pdev)
 138 {
 139         int i = 0;
 140
 141         freq_table = dev_get_platdata(&pdev->dev);
 142         if (!freq_table) {
 143                 pr_err("dbx500-cpufreq: Failed to fetch cpufreq table\n");
 144                 return -ENODEV;
 145         }
 146
 147         armss_clk = clk_get(&pdev->dev, "armss");
 148         if (IS_ERR(armss_clk)) {
 149                 pr_err("dbx500-cpufreq: Failed to get armss clk\n");
 150                 return PTR_ERR(armss_clk);
 151         }
 152
 153         pr_info("dbx500-cpufreq: Available frequencies:\n");
 154         while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
 155                 pr_info("  %d Mhz\n", freq_table[i].frequency/1000);
 156                 i++;
 157         }
 158
 159         return cpufreq_register_driver(&dbx500_cpufreq_driver);
 160 }
 161
 162 static struct platform_driver dbx500_cpufreq_plat_driver = {
 163         .driver = {
 164                 .name = "cpufreq-ux500",
 165                 .owner = THIS_MODULE,
 166         },
 167         .probe = dbx500_cpufreq_probe,
 168 };
 169
 170 static int __init dbx500_cpufreq_register(void)
 171 {
 172         if (!cpu_is_u8500_family())
 173                 return -ENODEV;
 174
 175         return platform_driver_register(&dbx500_cpufreq_plat_driver);
 176 }
 177 device_initcall(dbx500_cpufreq_register);
 178
 179 MODULE_LICENSE("GPL v2");
 180 MODULE_DESCRIPTION("cpufreq driver for DBX500");