LXR linux/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
  26static 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}
 107device_initcall(armada_xp_pmsu_cpufreq_init);
 108