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 index)
  24 {
  25         /* update armss clk frequency */
  26         return clk_set_rate(armss_clk, freq_table[index].frequency * 1000);
  27 }
  28
  29 static unsigned int dbx500_cpufreq_getspeed(unsigned int cpu)
  30 {
  31         int i = 0;
  32         unsigned long freq = clk_get_rate(armss_clk) / 1000;
  33
  34         /* The value is rounded to closest frequency in the defined table. */
  35         while (freq_table[i + 1].frequency != CPUFREQ_TABLE_END) {
  36                 if (freq < freq_table[i].frequency +
  37                    (freq_table[i + 1].frequency - freq_table[i].frequency) / 2)
  38                         return freq_table[i].frequency;
  39                 i++;
  40         }
  41
  42         return freq_table[i].frequency;
  43 }
  44
  45 static int dbx500_cpufreq_init(struct cpufreq_policy *policy)
  46 {
  47         return cpufreq_generic_init(policy, freq_table, 20 * 1000);
  48 }
  49
  50 static struct cpufreq_driver dbx500_cpufreq_driver = {
  51         .flags  = CPUFREQ_STICKY | CPUFREQ_CONST_LOOPS,
  52         .verify = cpufreq_generic_frequency_table_verify,
  53         .target_index = dbx500_cpufreq_target,
  54         .get    = dbx500_cpufreq_getspeed,
  55         .init   = dbx500_cpufreq_init,
  56         .name   = "DBX500",
  57         .attr   = cpufreq_generic_attr,
  58 };
  59
  60 static int dbx500_cpufreq_probe(struct platform_device *pdev)
  61 {
  62         int i = 0;
  63
  64         freq_table = dev_get_platdata(&pdev->dev);
  65         if (!freq_table) {
  66                 pr_err("dbx500-cpufreq: Failed to fetch cpufreq table\n");
  67                 return -ENODEV;
  68         }
  69
  70         armss_clk = clk_get(&pdev->dev, "armss");
  71         if (IS_ERR(armss_clk)) {
  72                 pr_err("dbx500-cpufreq: Failed to get armss clk\n");
  73                 return PTR_ERR(armss_clk);
  74         }
  75
  76         pr_info("dbx500-cpufreq: Available frequencies:\n");
  77         while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
  78                 pr_info("  %d Mhz\n", freq_table[i].frequency/1000);
  79                 i++;
  80         }
  81
  82         return cpufreq_register_driver(&dbx500_cpufreq_driver);
  83 }
  84
  85 static struct platform_driver dbx500_cpufreq_plat_driver = {
  86         .driver = {
  87                 .name = "cpufreq-ux500",
  88                 .owner = THIS_MODULE,
  89         },
  90         .probe = dbx500_cpufreq_probe,
  91 };
  92
  93 static int __init dbx500_cpufreq_register(void)
  94 {
  95         return platform_driver_register(&dbx500_cpufreq_plat_driver);
  96 }
  97 device_initcall(dbx500_cpufreq_register);
  98
  99 MODULE_LICENSE("GPL v2");
 100 MODULE_DESCRIPTION("cpufreq driver for DBX500");