drivers/cpufreq/sun50i-cpufreq-nvmem.c

   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
  25 static struct platform_device *cpufreq_dt_pdev, *sun50i_cpufreq_pdev;
  26
  27 /**
  28  * sun50i_cpufreq_get_efuse() - Parse and return efuse value present on SoC
  29  * @versions: Set to the value parsed from efuse
  30  *
  31  * Returns 0 if success.
  32  */
  33 static 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         switch (efuse_value) {
  73         case 0b0001:
  74                 *versions = 1;
  75                 break;
  76         case 0b0011:
  77                 *versions = 2;
  78                 break;
  79         default:
  80                 /*
  81                  * For other situations, we treat it as bin0.
  82                  * This vf table can be run for any good cpu.
  83                  */
  84                 *versions = 0;
  85                 break;
  86         }
  87
  88         kfree(speedbin);
  89         return 0;
  90 };
  91
  92 static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
  93 {
  94         struct opp_table **opp_tables;
  95         char name[MAX_NAME_LEN];
  96         unsigned int cpu;
  97         u32 speed = 0;
  98         int ret;
  99
 100         opp_tables = kcalloc(num_possible_cpus(), sizeof(*opp_tables),
 101                              GFP_KERNEL);
 102         if (!opp_tables)
 103                 return -ENOMEM;
 104
 105         ret = sun50i_cpufreq_get_efuse(&speed);
 106         if (ret)
 107                 return ret;
 108
 109         snprintf(name, MAX_NAME_LEN, "speed%d", speed);
 110
 111         for_each_possible_cpu(cpu) {
 112                 struct device *cpu_dev = get_cpu_device(cpu);
 113
 114                 if (!cpu_dev) {
 115                         ret = -ENODEV;
 116                         goto free_opp;
 117                 }
 118
 119                 opp_tables[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
 120                 if (IS_ERR(opp_tables[cpu])) {
 121                         ret = PTR_ERR(opp_tables[cpu]);
 122                         pr_err("Failed to set prop name\n");
 123                         goto free_opp;
 124                 }
 125         }
 126
 127         cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
 128                                                           NULL, 0);
 129         if (!IS_ERR(cpufreq_dt_pdev)) {
 130                 platform_set_drvdata(pdev, opp_tables);
 131                 return 0;
 132         }
 133
 134         ret = PTR_ERR(cpufreq_dt_pdev);
 135         pr_err("Failed to register platform device\n");
 136
 137 free_opp:
 138         for_each_possible_cpu(cpu) {
 139                 if (IS_ERR_OR_NULL(opp_tables[cpu]))
 140                         break;
 141                 dev_pm_opp_put_prop_name(opp_tables[cpu]);
 142         }
 143         kfree(opp_tables);
 144
 145         return ret;
 146 }
 147
 148 static int sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
 149 {
 150         struct opp_table **opp_tables = platform_get_drvdata(pdev);
 151         unsigned int cpu;
 152
 153         platform_device_unregister(cpufreq_dt_pdev);
 154
 155         for_each_possible_cpu(cpu)
 156                 dev_pm_opp_put_prop_name(opp_tables[cpu]);
 157
 158         kfree(opp_tables);
 159
 160         return 0;
 161 }
 162
 163 static struct platform_driver sun50i_cpufreq_driver = {
 164         .probe = sun50i_cpufreq_nvmem_probe,
 165         .remove = sun50i_cpufreq_nvmem_remove,
 166         .driver = {
 167                 .name = "sun50i-cpufreq-nvmem",
 168         },
 169 };
 170
 171 static const struct of_device_id sun50i_cpufreq_match_list[] = {
 172         { .compatible = "allwinner,sun50i-h6" },
 173         {}
 174 };
 175
 176 static const struct of_device_id *sun50i_cpufreq_match_node(void)
 177 {
 178         const struct of_device_id *match;
 179         struct device_node *np;
 180
 181         np = of_find_node_by_path("/");
 182         match = of_match_node(sun50i_cpufreq_match_list, np);
 183         of_node_put(np);
 184
 185         return match;
 186 }
 187
 188 /*
 189  * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
 190  * all the real activity is done in the probe, which may be defered as well.
 191  * The init here is only registering the driver and the platform device.
 192  */
 193 static int __init sun50i_cpufreq_init(void)
 194 {
 195         const struct of_device_id *match;
 196         int ret;
 197
 198         match = sun50i_cpufreq_match_node();
 199         if (!match)
 200                 return -ENODEV;
 201
 202         ret = platform_driver_register(&sun50i_cpufreq_driver);
 203         if (unlikely(ret < 0))
 204                 return ret;
 205
 206         sun50i_cpufreq_pdev =
 207                 platform_device_register_simple("sun50i-cpufreq-nvmem",
 208                                                 -1, NULL, 0);
 209         ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
 210         if (ret == 0)
 211                 return 0;
 212
 213         platform_driver_unregister(&sun50i_cpufreq_driver);
 214         return ret;
 215 }
 216 module_init(sun50i_cpufreq_init);
 217
 218 static void __exit sun50i_cpufreq_exit(void)
 219 {
 220         platform_device_unregister(sun50i_cpufreq_pdev);
 221         platform_driver_unregister(&sun50i_cpufreq_driver);
 222 }
 223 module_exit(sun50i_cpufreq_exit);
 224
 225 MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
 226 MODULE_LICENSE("GPL v2");