linux/drivers/cpufreq/sun50i-cpufreq-nvmem.c
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   1// SPDX-License-Identifier: GPL-2.0
   2/*
   3 * Allwinner CPUFreq nvmem based driver
   4 *
   5 * The sun50i-cpufreq-nvmem driver reads the efuse value from the SoC to
   6 * provide the OPP framework with required information.
   7 *
   8 * Copyright (C) 2019 Yangtao Li <tiny.windzz@gmail.com>
   9 */
  10
  11#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  12
  13#include <linux/module.h>
  14#include <linux/nvmem-consumer.h>
  15#include <linux/of_device.h>
  16#include <linux/platform_device.h>
  17#include <linux/pm_opp.h>
  18#include <linux/slab.h>
  19
  20#define MAX_NAME_LEN    7
  21
  22#define NVMEM_MASK      0x7
  23#define NVMEM_SHIFT     5
  24
  25static struct platform_device *cpufreq_dt_pdev, *sun50i_cpufreq_pdev;
  26
  27/**
  28 * sun50i_cpufreq_get_efuse() - Determine speed grade from efuse value
  29 * @versions: Set to the value parsed from efuse
  30 *
  31 * Returns 0 if success.
  32 */
  33static int sun50i_cpufreq_get_efuse(u32 *versions)
  34{
  35        struct nvmem_cell *speedbin_nvmem;
  36        struct device_node *np;
  37        struct device *cpu_dev;
  38        u32 *speedbin, efuse_value;
  39        size_t len;
  40        int ret;
  41
  42        cpu_dev = get_cpu_device(0);
  43        if (!cpu_dev)
  44                return -ENODEV;
  45
  46        np = dev_pm_opp_of_get_opp_desc_node(cpu_dev);
  47        if (!np)
  48                return -ENOENT;
  49
  50        ret = of_device_is_compatible(np,
  51                                      "allwinner,sun50i-h6-operating-points");
  52        if (!ret) {
  53                of_node_put(np);
  54                return -ENOENT;
  55        }
  56
  57        speedbin_nvmem = of_nvmem_cell_get(np, NULL);
  58        of_node_put(np);
  59        if (IS_ERR(speedbin_nvmem)) {
  60                if (PTR_ERR(speedbin_nvmem) != -EPROBE_DEFER)
  61                        pr_err("Could not get nvmem cell: %ld\n",
  62                               PTR_ERR(speedbin_nvmem));
  63                return PTR_ERR(speedbin_nvmem);
  64        }
  65
  66        speedbin = nvmem_cell_read(speedbin_nvmem, &len);
  67        nvmem_cell_put(speedbin_nvmem);
  68        if (IS_ERR(speedbin))
  69                return PTR_ERR(speedbin);
  70
  71        efuse_value = (*speedbin >> NVMEM_SHIFT) & NVMEM_MASK;
  72
  73        /*
  74         * We treat unexpected efuse values as if the SoC was from
  75         * the slowest bin. Expected efuse values are 1-3, slowest
  76         * to fastest.
  77         */
  78        if (efuse_value >= 1 && efuse_value <= 3)
  79                *versions = efuse_value - 1;
  80        else
  81                *versions = 0;
  82
  83        kfree(speedbin);
  84        return 0;
  85};
  86
  87static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
  88{
  89        struct opp_table **opp_tables;
  90        char name[MAX_NAME_LEN];
  91        unsigned int cpu;
  92        u32 speed = 0;
  93        int ret;
  94
  95        opp_tables = kcalloc(num_possible_cpus(), sizeof(*opp_tables),
  96                             GFP_KERNEL);
  97        if (!opp_tables)
  98                return -ENOMEM;
  99
 100        ret = sun50i_cpufreq_get_efuse(&speed);
 101        if (ret)
 102                return ret;
 103
 104        snprintf(name, MAX_NAME_LEN, "speed%d", speed);
 105
 106        for_each_possible_cpu(cpu) {
 107                struct device *cpu_dev = get_cpu_device(cpu);
 108
 109                if (!cpu_dev) {
 110                        ret = -ENODEV;
 111                        goto free_opp;
 112                }
 113
 114                opp_tables[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
 115                if (IS_ERR(opp_tables[cpu])) {
 116                        ret = PTR_ERR(opp_tables[cpu]);
 117                        pr_err("Failed to set prop name\n");
 118                        goto free_opp;
 119                }
 120        }
 121
 122        cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
 123                                                          NULL, 0);
 124        if (!IS_ERR(cpufreq_dt_pdev)) {
 125                platform_set_drvdata(pdev, opp_tables);
 126                return 0;
 127        }
 128
 129        ret = PTR_ERR(cpufreq_dt_pdev);
 130        pr_err("Failed to register platform device\n");
 131
 132free_opp:
 133        for_each_possible_cpu(cpu) {
 134                if (IS_ERR_OR_NULL(opp_tables[cpu]))
 135                        break;
 136                dev_pm_opp_put_prop_name(opp_tables[cpu]);
 137        }
 138        kfree(opp_tables);
 139
 140        return ret;
 141}
 142
 143static int sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
 144{
 145        struct opp_table **opp_tables = platform_get_drvdata(pdev);
 146        unsigned int cpu;
 147
 148        platform_device_unregister(cpufreq_dt_pdev);
 149
 150        for_each_possible_cpu(cpu)
 151                dev_pm_opp_put_prop_name(opp_tables[cpu]);
 152
 153        kfree(opp_tables);
 154
 155        return 0;
 156}
 157
 158static struct platform_driver sun50i_cpufreq_driver = {
 159        .probe = sun50i_cpufreq_nvmem_probe,
 160        .remove = sun50i_cpufreq_nvmem_remove,
 161        .driver = {
 162                .name = "sun50i-cpufreq-nvmem",
 163        },
 164};
 165
 166static const struct of_device_id sun50i_cpufreq_match_list[] = {
 167        { .compatible = "allwinner,sun50i-h6" },
 168        {}
 169};
 170MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list);
 171
 172static const struct of_device_id *sun50i_cpufreq_match_node(void)
 173{
 174        const struct of_device_id *match;
 175        struct device_node *np;
 176
 177        np = of_find_node_by_path("/");
 178        match = of_match_node(sun50i_cpufreq_match_list, np);
 179        of_node_put(np);
 180
 181        return match;
 182}
 183
 184/*
 185 * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
 186 * all the real activity is done in the probe, which may be defered as well.
 187 * The init here is only registering the driver and the platform device.
 188 */
 189static int __init sun50i_cpufreq_init(void)
 190{
 191        const struct of_device_id *match;
 192        int ret;
 193
 194        match = sun50i_cpufreq_match_node();
 195        if (!match)
 196                return -ENODEV;
 197
 198        ret = platform_driver_register(&sun50i_cpufreq_driver);
 199        if (unlikely(ret < 0))
 200                return ret;
 201
 202        sun50i_cpufreq_pdev =
 203                platform_device_register_simple("sun50i-cpufreq-nvmem",
 204                                                -1, NULL, 0);
 205        ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
 206        if (ret == 0)
 207                return 0;
 208
 209        platform_driver_unregister(&sun50i_cpufreq_driver);
 210        return ret;
 211}
 212module_init(sun50i_cpufreq_init);
 213
 214static void __exit sun50i_cpufreq_exit(void)
 215{
 216        platform_device_unregister(sun50i_cpufreq_pdev);
 217        platform_driver_unregister(&sun50i_cpufreq_driver);
 218}
 219module_exit(sun50i_cpufreq_exit);
 220
 221MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
 222MODULE_LICENSE("GPL v2");
 223