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         /* 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         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  59
  60         /* update armss clk frequency */
  61         ret = clk_set_rate(armss_clk, freqs.new * 1000);
  62
  63         if (ret) {
  64                 pr_err("dbx500-cpufreq: Failed to set armss_clk to %d Hz: error %d\n",
  65                        freqs.new * 1000, ret);
  66                 return ret;
  67         }
  68
  69         /* post change notification */
  70         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
  71
  72         return 0;
  73 }
  74
  75 static unsigned int dbx500_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("dbx500-cpufreq: Failed to find cpufreq speed\n");
  88         return 0;
  89 }
  90
  91 static int __cpuinit dbx500_cpufreq_init(struct cpufreq_policy *policy)
  92 {
  93         int res;
  94
  95         /* get policy fields based on the table */
  96         res = cpufreq_frequency_table_cpuinfo(policy, freq_table);
  97         if (!res)
  98                 cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
  99         else {
 100                 pr_err("dbx500-cpufreq: Failed to read policy table\n");
 101                 return res;
 102         }
 103
 104         policy->min = policy->cpuinfo.min_freq;
 105         policy->max = policy->cpuinfo.max_freq;
 106         policy->cur = dbx500_cpufreq_getspeed(policy->cpu);
 107         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 108
 109         /*
 110          * FIXME : Need to take time measurement across the target()
 111          *         function with no/some/all drivers in the notification
 112          *         list.
 113          */
 114         policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */
 115
 116         /* policy sharing between dual CPUs */
 117         cpumask_setall(policy->cpus);
 118
 119         return 0;
 120 }
 121
 122 static struct cpufreq_driver dbx500_cpufreq_driver = {
 123         .flags  = CPUFREQ_STICKY | CPUFREQ_CONST_LOOPS,
 124         .verify = dbx500_cpufreq_verify_speed,
 125         .target = dbx500_cpufreq_target,
 126         .get    = dbx500_cpufreq_getspeed,
 127         .init   = dbx500_cpufreq_init,
 128         .name   = "DBX500",
 129         .attr   = dbx500_cpufreq_attr,
 130 };
 131
 132 static int dbx500_cpufreq_probe(struct platform_device *pdev)
 133 {
 134         int i = 0;
 135
 136         freq_table = dev_get_platdata(&pdev->dev);
 137         if (!freq_table) {
 138                 pr_err("dbx500-cpufreq: Failed to fetch cpufreq table\n");
 139                 return -ENODEV;
 140         }
 141
 142         armss_clk = clk_get(&pdev->dev, "armss");
 143         if (IS_ERR(armss_clk)) {
 144                 pr_err("dbx500-cpufreq: Failed to get armss clk\n");
 145                 return PTR_ERR(armss_clk);
 146         }
 147
 148         pr_info("dbx500-cpufreq: Available frequencies:\n");
 149         while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
 150                 pr_info("  %d Mhz\n", freq_table[i].frequency/1000);
 151                 i++;
 152         }
 153
 154         return cpufreq_register_driver(&dbx500_cpufreq_driver);
 155 }
 156
 157 static struct platform_driver dbx500_cpufreq_plat_driver = {
 158         .driver = {
 159                 .name = "cpufreq-ux500",
 160                 .owner = THIS_MODULE,
 161         },
 162         .probe = dbx500_cpufreq_probe,
 163 };
 164
 165 static int __init dbx500_cpufreq_register(void)
 166 {
 167         return platform_driver_register(&dbx500_cpufreq_plat_driver);
 168 }
 169 device_initcall(dbx500_cpufreq_register);
 170
 171 MODULE_LICENSE("GPL v2");
 172 MODULE_DESCRIPTION("cpufreq driver for DBX500");