drivers/cpufreq/dbx500-cpufreq.c

   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
  19 static struct cpufreq_frequency_table *freq_table;
  20 static struct clk *armss_clk;
  21
  22 static struct freq_attr *dbx500_cpufreq_attr[] = {
  23         &cpufreq_freq_attr_scaling_available_freqs,
  24         NULL,
  25 };
  26
  27 static int dbx500_cpufreq_verify_speed(struct cpufreq_policy *policy)
  28 {
  29         return cpufreq_frequency_table_verify(policy, freq_table);
  30 }
  31
  32 static 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         /* Lookup the next frequency */
  41         if (cpufreq_frequency_table_target(policy, freq_table, target_freq,
  42                                         relation, &idx))
  43                 return -EINVAL;
  44
  45         freqs.old = policy->cur;
  46         freqs.new = freq_table[idx].frequency;
  47
  48         if (freqs.old == freqs.new)
  49                 return 0;
  50
  51         /* pre-change notification */
  52         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  53
  54         /* update armss clk frequency */
  55         ret = clk_set_rate(armss_clk, freqs.new * 1000);
  56
  57         if (ret) {
  58                 pr_err("dbx500-cpufreq: Failed to set armss_clk to %d Hz: error %d\n",
  59                        freqs.new * 1000, ret);
  60                 freqs.new = freqs.old;
  61         }
  62
  63         /* post change notification */
  64         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
  65
  66         return ret;
  67 }
  68
  69 static unsigned int dbx500_cpufreq_getspeed(unsigned int cpu)
  70 {
  71         int i = 0;
  72         unsigned long freq = clk_get_rate(armss_clk) / 1000;
  73
  74         /* The value is rounded to closest frequency in the defined table. */
  75         while (freq_table[i + 1].frequency != CPUFREQ_TABLE_END) {
  76                 if (freq < freq_table[i].frequency +
  77                    (freq_table[i + 1].frequency - freq_table[i].frequency) / 2)
  78                         return freq_table[i].frequency;
  79                 i++;
  80         }
  81
  82         return freq_table[i].frequency;
  83 }
  84
  85 static int dbx500_cpufreq_init(struct cpufreq_policy *policy)
  86 {
  87         int res;
  88
  89         /* get policy fields based on the table */
  90         res = cpufreq_table_validate_and_show(policy, freq_table);
  91         if (res) {
  92                 pr_err("dbx500-cpufreq: Failed to read policy table\n");
  93                 return res;
  94         }
  95
  96         policy->min = policy->cpuinfo.min_freq;
  97         policy->max = policy->cpuinfo.max_freq;
  98         policy->cur = dbx500_cpufreq_getspeed(policy->cpu);
  99         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 100
 101         /*
 102          * FIXME : Need to take time measurement across the target()
 103          *         function with no/some/all drivers in the notification
 104          *         list.
 105          */
 106         policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */
 107
 108         /* policy sharing between dual CPUs */
 109         cpumask_setall(policy->cpus);
 110
 111         return 0;
 112 }
 113
 114 static struct cpufreq_driver dbx500_cpufreq_driver = {
 115         .flags  = CPUFREQ_STICKY | CPUFREQ_CONST_LOOPS,
 116         .verify = dbx500_cpufreq_verify_speed,
 117         .target = dbx500_cpufreq_target,
 118         .get    = dbx500_cpufreq_getspeed,
 119         .init   = dbx500_cpufreq_init,
 120         .name   = "DBX500",
 121         .attr   = dbx500_cpufreq_attr,
 122 };
 123
 124 static int dbx500_cpufreq_probe(struct platform_device *pdev)
 125 {
 126         int i = 0;
 127
 128         freq_table = dev_get_platdata(&pdev->dev);
 129         if (!freq_table) {
 130                 pr_err("dbx500-cpufreq: Failed to fetch cpufreq table\n");
 131                 return -ENODEV;
 132         }
 133
 134         armss_clk = clk_get(&pdev->dev, "armss");
 135         if (IS_ERR(armss_clk)) {
 136                 pr_err("dbx500-cpufreq: Failed to get armss clk\n");
 137                 return PTR_ERR(armss_clk);
 138         }
 139
 140         pr_info("dbx500-cpufreq: Available frequencies:\n");
 141         while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
 142                 pr_info("  %d Mhz\n", freq_table[i].frequency/1000);
 143                 i++;
 144         }
 145
 146         return cpufreq_register_driver(&dbx500_cpufreq_driver);
 147 }
 148
 149 static struct platform_driver dbx500_cpufreq_plat_driver = {
 150         .driver = {
 151                 .name = "cpufreq-ux500",
 152                 .owner = THIS_MODULE,
 153         },
 154         .probe = dbx500_cpufreq_probe,
 155 };
 156
 157 static int __init dbx500_cpufreq_register(void)
 158 {
 159         return platform_driver_register(&dbx500_cpufreq_plat_driver);
 160 }
 161 device_initcall(dbx500_cpufreq_register);
 162
 163 MODULE_LICENSE("GPL v2");
 164 MODULE_DESCRIPTION("cpufreq driver for DBX500");