drivers/cpufreq/db8500-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 *db8500_cpufreq_attr[] = {
  24         &cpufreq_freq_attr_scaling_available_freqs,
  25         NULL,
  26 };
  27
  28 static int db8500_cpufreq_verify_speed(struct cpufreq_policy *policy)
  29 {
  30         return cpufreq_frequency_table_verify(policy, freq_table);
  31 }
  32
  33 static int db8500_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
  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
  48             (policy, freq_table, target_freq, relation, &idx)) {
  49                 return -EINVAL;
  50         }
  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         if (clk_set_rate(armss_clk, freq_table[idx].frequency * 1000)) {
  64                 pr_err("db8500-cpufreq: Failed to update armss clk\n");
  65                 return -EINVAL;
  66         }
  67
  68         /* post change notification */
  69         for_each_cpu(freqs.cpu, policy->cpus)
  70                 cpufreq_notify_transition(&freqs, CPUFREQ_POSTCHANGE);
  71
  72         return 0;
  73 }
  74
  75 static unsigned int db8500_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("db8500-cpufreq: Failed to find cpufreq speed\n");
  88         return 0;
  89 }
  90
  91 static int __cpuinit db8500_cpufreq_init(struct cpufreq_policy *policy)
  92 {
  93         int i = 0;
  94         int res;
  95
  96         armss_clk = clk_get(NULL, "armss");
  97         if (IS_ERR(armss_clk)) {
  98                 pr_err("db8500-cpufreq : Failed to get armss clk\n");
  99                 return PTR_ERR(armss_clk);
 100         }
 101
 102         pr_info("db8500-cpufreq : Available frequencies:\n");
 103         while (freq_table[i].frequency != CPUFREQ_TABLE_END) {
 104                 pr_info("  %d Mhz\n", freq_table[i].frequency/1000);
 105                 i++;
 106         }
 107
 108         /* get policy fields based on the table */
 109         res = cpufreq_frequency_table_cpuinfo(policy, freq_table);
 110         if (!res)
 111                 cpufreq_frequency_table_get_attr(freq_table, policy->cpu);
 112         else {
 113                 pr_err("db8500-cpufreq : Failed to read policy table\n");
 114                 clk_put(armss_clk);
 115                 return res;
 116         }
 117
 118         policy->min = policy->cpuinfo.min_freq;
 119         policy->max = policy->cpuinfo.max_freq;
 120         policy->cur = db8500_cpufreq_getspeed(policy->cpu);
 121         policy->governor = CPUFREQ_DEFAULT_GOVERNOR;
 122
 123         /*
 124          * FIXME : Need to take time measurement across the target()
 125          *         function with no/some/all drivers in the notification
 126          *         list.
 127          */
 128         policy->cpuinfo.transition_latency = 20 * 1000; /* in ns */
 129
 130         /* policy sharing between dual CPUs */
 131         cpumask_copy(policy->cpus, cpu_present_mask);
 132
 133         policy->shared_type = CPUFREQ_SHARED_TYPE_ALL;
 134
 135         return 0;
 136 }
 137
 138 static struct cpufreq_driver db8500_cpufreq_driver = {
 139         .flags  = CPUFREQ_STICKY,
 140         .verify = db8500_cpufreq_verify_speed,
 141         .target = db8500_cpufreq_target,
 142         .get    = db8500_cpufreq_getspeed,
 143         .init   = db8500_cpufreq_init,
 144         .name   = "DB8500",
 145         .attr   = db8500_cpufreq_attr,
 146 };
 147
 148 static int db8500_cpufreq_probe(struct platform_device *pdev)
 149 {
 150         freq_table = dev_get_platdata(&pdev->dev);
 151
 152         if (!freq_table) {
 153                 pr_err("db8500-cpufreq: Failed to fetch cpufreq table\n");
 154                 return -ENODEV;
 155         }
 156
 157         return cpufreq_register_driver(&db8500_cpufreq_driver);
 158 }
 159
 160 static struct platform_driver db8500_cpufreq_plat_driver = {
 161         .driver = {
 162                 .name = "cpufreq-u8500",
 163                 .owner = THIS_MODULE,
 164         },
 165         .probe = db8500_cpufreq_probe,
 166 };
 167
 168 static int __init db8500_cpufreq_register(void)
 169 {
 170         if (!cpu_is_u8500_family())
 171                 return -ENODEV;
 172
 173         pr_info("cpufreq for DB8500 started\n");
 174         return platform_driver_register(&db8500_cpufreq_plat_driver);
 175 }
 176 device_initcall(db8500_cpufreq_register);
 177
 178 MODULE_LICENSE("GPL v2");
 179 MODULE_DESCRIPTION("cpufreq driver for DB8500");