drivers/cpufreq/mvebu-cpufreq.c

   1 /*
   2  * CPUFreq support for Armada 370/XP platforms.
   3  *
   4  * Copyright (C) 2012-2016 Marvell
   5  *
   6  * Yehuda Yitschak <yehuday@marvell.com>
   7  * Gregory Clement <gregory.clement@free-electrons.com>
   8  * Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
   9  *
  10  * This file is licensed under the terms of the GNU General Public
  11  * License version 2.  This program is licensed "as is" without any
  12  * warranty of any kind, whether express or implied.
  13  */
  14
  15 #define pr_fmt(fmt) "mvebu-pmsu: " fmt
  16
  17 #include <linux/clk.h>
  18 #include <linux/cpu.h>
  19 #include <linux/init.h>
  20 #include <linux/kernel.h>
  21 #include <linux/of_address.h>
  22 #include <linux/platform_device.h>
  23 #include <linux/pm_opp.h>
  24 #include <linux/resource.h>
  25
  26 static int __init armada_xp_pmsu_cpufreq_init(void)
  27 {
  28         struct device_node *np;
  29         struct resource res;
  30         int ret, cpu;
  31
  32         if (!of_machine_is_compatible("marvell,armadaxp"))
  33                 return 0;
  34
  35         /*
  36          * In order to have proper cpufreq handling, we need to ensure
  37          * that the Device Tree description of the CPU clock includes
  38          * the definition of the PMU DFS registers. If not, we do not
  39          * register the clock notifier and the cpufreq driver. This
  40          * piece of code is only for compatibility with old Device
  41          * Trees.
  42          */
  43         np = of_find_compatible_node(NULL, NULL, "marvell,armada-xp-cpu-clock");
  44         if (!np)
  45                 return 0;
  46
  47         ret = of_address_to_resource(np, 1, &res);
  48         if (ret) {
  49                 pr_warn(FW_WARN "not enabling cpufreq, deprecated armada-xp-cpu-clock binding\n");
  50                 of_node_put(np);
  51                 return 0;
  52         }
  53
  54         of_node_put(np);
  55
  56         /*
  57          * For each CPU, this loop registers the operating points
  58          * supported (which are the nominal CPU frequency and half of
  59          * it), and registers the clock notifier that will take care
  60          * of doing the PMSU part of a frequency transition.
  61          */
  62         for_each_possible_cpu(cpu) {
  63                 struct device *cpu_dev;
  64                 struct clk *clk;
  65                 int ret;
  66
  67                 cpu_dev = get_cpu_device(cpu);
  68                 if (!cpu_dev) {
  69                         pr_err("Cannot get CPU %d\n", cpu);
  70                         continue;
  71                 }
  72
  73                 clk = clk_get(cpu_dev, NULL);
  74                 if (IS_ERR(clk)) {
  75                         pr_err("Cannot get clock for CPU %d\n", cpu);
  76                         return PTR_ERR(clk);
  77                 }
  78
  79                 /*
  80                  * In case of a failure of dev_pm_opp_add(), we don't
  81                  * bother with cleaning up the registered OPP (there's
  82                  * no function to do so), and simply cancel the
  83                  * registration of the cpufreq device.
  84                  */
  85                 ret = dev_pm_opp_add(cpu_dev, clk_get_rate(clk), 0);
  86                 if (ret) {
  87                         clk_put(clk);
  88                         return ret;
  89                 }
  90
  91                 ret = dev_pm_opp_add(cpu_dev, clk_get_rate(clk) / 2, 0);
  92                 if (ret) {
  93                         clk_put(clk);
  94                         return ret;
  95                 }
  96
  97                 ret = dev_pm_opp_set_sharing_cpus(cpu_dev,
  98                                                   cpumask_of(cpu_dev->id));
  99                 if (ret)
 100                         dev_err(cpu_dev, "%s: failed to mark OPPs as shared: %d\n",
 101                                 __func__, ret);
 102         }
 103
 104         platform_device_register_simple("cpufreq-dt", -1, NULL, 0);
 105         return 0;
 106 }
 107 device_initcall(armada_xp_pmsu_cpufreq_init);