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 int dbx500_cpufreq_target(struct cpufreq_policy *policy,
  23                                 unsigned int target_freq,
  24                                 unsigned int relation)
  25 {
  26         struct cpufreq_freqs freqs;
  27         unsigned int idx;
  28         int ret;
  29
  30         /* Lookup the next frequency */
  31         if (cpufreq_frequency_table_target(policy, freq_table, target_freq,
  32                                         relation, &idx))
  33                 return -EINVAL;
  34
  35         freqs.old = policy->cur;
  36         freqs.new = freq_table[idx].frequency;
  37
  38         if (freqs.old == freqs.new)
  39                 return 0;
  40
  41         /* pre-change notification */
  42         cpufreq_notify_transition(policy, &freqs, CPUFREQ_PRECHANGE);
  43
  44         /* update armss clk frequency */
  45         ret = clk_set_rate(armss_clk, freqs.new * 1000);
  46
  47         if (ret) {
  48                 pr_err("dbx500-cpufreq: Failed to set armss_clk to %d Hz: error %d\n",
  49                        freqs.new * 1000, ret);
  50                 freqs.new = freqs.old;
  51         }
  52
  53         /* post change notification */
  54         cpufreq_notify_transition(policy, &freqs, CPUFREQ_POSTCHANGE);
  55
  56         return ret;
  57 }
  58
  59 static unsigned int dbx500_cpufreq_getspeed(unsigned int cpu)
  60 {
  61         int i = 0;
  62         unsigned long freq = clk_get_rate(armss_clk) / 1000;
  63
  64         /* The value is rounded to closest frequency in the defined table. */
  65         while (freq_table[i + 1].frequency != CPUFREQ_TABLE_END) {
  66                 if (freq < freq_table[i].frequency +
  67                    (freq_table[i + 1].frequency - freq_table[i].frequency) / 2)
  68                         return freq_table[i].frequency;
  69                 i++;
  70         }
  71
  72         return freq_table[i].frequency;
  73 }
  74
  75 static int dbx500_cpufreq_init(struct cpufreq_policy *policy)
  76 {
  77         int res;
  78
  79         /* get policy fields based on the table */
  80         res = cpufreq_table_validate_and_show(policy, freq_table);
  81         if (res) {
  82                 pr_err("dbx500-cpufreq: Failed to read policy table\n");
  83                 return res;
  84         }
  85
  86         /*
  87          * FIXME : Need to take time measurement across the target()
  88          *         function with no/some/all drivers in the notification
  89          *         list.
  90          */
  91         policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */
  92
  93         /* policy sharing between dual CPUs */
  94         cpumask_setall(policy->cpus);
  95
  96         return 0;
  97 }
  98
  99 static struct cpufreq_driver dbx500_cpufreq_driver = {
 100         .flags  = CPUFREQ_STICKY | CPUFREQ_CONST_LOOPS,
 101         .verify = cpufreq_generic_frequency_table_verify,
 102         .target = dbx500_cpufreq_target,
 103         .get    = dbx500_cpufreq_getspeed,
 104         .init   = dbx500_cpufreq_init,
 105         .name   = "DBX500",
 106         .attr   = cpufreq_generic_attr,
 107 };
 108
 109 static int dbx500_cpufreq_probe(struct platform_device *pdev)
 110 {
 111         int i = 0;
 112
 113         freq_table = dev_get_platdata(&pdev->dev);
 114         if (!freq_table) {
 115                 pr_err("dbx500-cpufreq: Failed to fetch cpufreq table\n");
 116                 return -ENODEV;
 117         }
 118
 119         armss_clk = clk_get(&pdev->dev, "armss");
 120         if (IS_ERR(armss_clk)) {
 121                 pr_err("dbx500-cpufreq: Failed to get armss clk\n");
 122                 return PTR_ERR(armss_clk);
 123         }
 124
 125         pr_info("dbx500-cpufreq: Available frequencies:\n");
 126         while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
 127                 pr_info("  %d Mhz\n", freq_table[i].frequency/1000);
 128                 i++;
 129         }
 130
 131         return cpufreq_register_driver(&dbx500_cpufreq_driver);
 132 }
 133
 134 static struct platform_driver dbx500_cpufreq_plat_driver = {
 135         .driver = {
 136                 .name = "cpufreq-ux500",
 137                 .owner = THIS_MODULE,
 138         },
 139         .probe = dbx500_cpufreq_probe,
 140 };
 141
 142 static int __init dbx500_cpufreq_register(void)
 143 {
 144         return platform_driver_register(&dbx500_cpufreq_plat_driver);
 145 }
 146 device_initcall(dbx500_cpufreq_register);
 147
 148 MODULE_LICENSE("GPL v2");
 149 MODULE_DESCRIPTION("cpufreq driver for DBX500");