drivers/cpufreq/armada-8k-cpufreq.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * CPUFreq support for Armada 8K
   4  *
   5  * Copyright (C) 2018 Marvell
   6  *
   7  * Omri Itach <omrii@marvell.com>
   8  * Gregory Clement <gregory.clement@bootlin.com>
   9  */
  10
  11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13 #include <linux/clk.h>
  14 #include <linux/cpu.h>
  15 #include <linux/err.h>
  16 #include <linux/init.h>
  17 #include <linux/kernel.h>
  18 #include <linux/module.h>
  19 #include <linux/of.h>
  20 #include <linux/platform_device.h>
  21 #include <linux/pm_opp.h>
  22 #include <linux/slab.h>
  23
  24 /*
  25  * Setup the opps list with the divider for the max frequency, that
  26  * will be filled at runtime.
  27  */
  28 static const int opps_div[] __initconst = {1, 2, 3, 4};
  29
  30 static struct platform_device *armada_8k_pdev;
  31
  32 struct freq_table {
  33         struct device *cpu_dev;
  34         unsigned int freq[ARRAY_SIZE(opps_div)];
  35 };
  36
  37 /* If the CPUs share the same clock, then they are in the same cluster. */
  38 static void __init armada_8k_get_sharing_cpus(struct clk *cur_clk,
  39                                               struct cpumask *cpumask)
  40 {
  41         int cpu;
  42
  43         for_each_possible_cpu(cpu) {
  44                 struct device *cpu_dev;
  45                 struct clk *clk;
  46
  47                 cpu_dev = get_cpu_device(cpu);
  48                 if (!cpu_dev) {
  49                         pr_warn("Failed to get cpu%d device\n", cpu);
  50                         continue;
  51                 }
  52
  53                 clk = clk_get(cpu_dev, 0);
  54                 if (IS_ERR(clk)) {
  55                         pr_warn("Cannot get clock for CPU %d\n", cpu);
  56                 } else {
  57                         if (clk_is_match(clk, cur_clk))
  58                                 cpumask_set_cpu(cpu, cpumask);
  59
  60                         clk_put(clk);
  61                 }
  62         }
  63 }
  64
  65 static int __init armada_8k_add_opp(struct clk *clk, struct device *cpu_dev,
  66                                     struct freq_table *freq_tables,
  67                                     int opps_index)
  68 {
  69         unsigned int cur_frequency;
  70         unsigned int freq;
  71         int i, ret;
  72
  73         /* Get nominal (current) CPU frequency. */
  74         cur_frequency = clk_get_rate(clk);
  75         if (!cur_frequency) {
  76                 dev_err(cpu_dev, "Failed to get clock rate for this CPU\n");
  77                 return -EINVAL;
  78         }
  79
  80         freq_tables[opps_index].cpu_dev = cpu_dev;
  81
  82         for (i = 0; i < ARRAY_SIZE(opps_div); i++) {
  83                 freq = cur_frequency / opps_div[i];
  84
  85                 ret = dev_pm_opp_add(cpu_dev, freq, 0);
  86                 if (ret)
  87                         return ret;
  88
  89                 freq_tables[opps_index].freq[i] = freq;
  90         }
  91
  92         return 0;
  93 }
  94
  95 static void armada_8k_cpufreq_free_table(struct freq_table *freq_tables)
  96 {
  97         int opps_index, nb_cpus = num_possible_cpus();
  98
  99         for (opps_index = 0 ; opps_index <= nb_cpus; opps_index++) {
 100                 int i;
 101
 102                 /* If cpu_dev is NULL then we reached the end of the array */
 103                 if (!freq_tables[opps_index].cpu_dev)
 104                         break;
 105
 106                 for (i = 0; i < ARRAY_SIZE(opps_div); i++) {
 107                         /*
 108                          * A 0Hz frequency is not valid, this meant
 109                          * that it was not yet initialized so there is
 110                          * no more opp to free
 111                          */
 112                         if (freq_tables[opps_index].freq[i] == 0)
 113                                 break;
 114
 115                         dev_pm_opp_remove(freq_tables[opps_index].cpu_dev,
 116                                           freq_tables[opps_index].freq[i]);
 117                 }
 118         }
 119
 120         kfree(freq_tables);
 121 }
 122
 123 static int __init armada_8k_cpufreq_init(void)
 124 {
 125         int ret = 0, opps_index = 0, cpu, nb_cpus;
 126         struct freq_table *freq_tables;
 127         struct device_node *node;
 128         struct cpumask cpus;
 129
 130         node = of_find_compatible_node(NULL, NULL, "marvell,ap806-cpu-clock");
 131         if (!node || !of_device_is_available(node)) {
 132                 of_node_put(node);
 133                 return -ENODEV;
 134         }
 135
 136         nb_cpus = num_possible_cpus();
 137         freq_tables = kcalloc(nb_cpus, sizeof(*freq_tables), GFP_KERNEL);
 138         cpumask_copy(&cpus, cpu_possible_mask);
 139
 140         /*
 141          * For each CPU, this loop registers the operating points
 142          * supported (which are the nominal CPU frequency and full integer
 143          * divisions of it).
 144          */
 145         for_each_cpu(cpu, &cpus) {
 146                 struct cpumask shared_cpus;
 147                 struct device *cpu_dev;
 148                 struct clk *clk;
 149
 150                 cpu_dev = get_cpu_device(cpu);
 151
 152                 if (!cpu_dev) {
 153                         pr_err("Cannot get CPU %d\n", cpu);
 154                         continue;
 155                 }
 156
 157                 clk = clk_get(cpu_dev, 0);
 158
 159                 if (IS_ERR(clk)) {
 160                         pr_err("Cannot get clock for CPU %d\n", cpu);
 161                         ret = PTR_ERR(clk);
 162                         goto remove_opp;
 163                 }
 164
 165                 ret = armada_8k_add_opp(clk, cpu_dev, freq_tables, opps_index);
 166                 if (ret) {
 167                         clk_put(clk);
 168                         goto remove_opp;
 169                 }
 170
 171                 opps_index++;
 172                 cpumask_clear(&shared_cpus);
 173                 armada_8k_get_sharing_cpus(clk, &shared_cpus);
 174                 dev_pm_opp_set_sharing_cpus(cpu_dev, &shared_cpus);
 175                 cpumask_andnot(&cpus, &cpus, &shared_cpus);
 176                 clk_put(clk);
 177         }
 178
 179         armada_8k_pdev = platform_device_register_simple("cpufreq-dt", -1,
 180                                                          NULL, 0);
 181         ret = PTR_ERR_OR_ZERO(armada_8k_pdev);
 182         if (ret)
 183                 goto remove_opp;
 184
 185         platform_set_drvdata(armada_8k_pdev, freq_tables);
 186
 187         return 0;
 188
 189 remove_opp:
 190         armada_8k_cpufreq_free_table(freq_tables);
 191         return ret;
 192 }
 193 module_init(armada_8k_cpufreq_init);
 194
 195 static void __exit armada_8k_cpufreq_exit(void)
 196 {
 197         struct freq_table *freq_tables = platform_get_drvdata(armada_8k_pdev);
 198
 199         platform_device_unregister(armada_8k_pdev);
 200         armada_8k_cpufreq_free_table(freq_tables);
 201 }
 202 module_exit(armada_8k_cpufreq_exit);
 203
 204 MODULE_AUTHOR("Gregory Clement <gregory.clement@bootlin.com>");
 205 MODULE_DESCRIPTION("Armada 8K cpufreq driver");
 206 MODULE_LICENSE("GPL");