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() - Determine speed grade from efuse value
  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                 return dev_err_probe(cpu_dev, PTR_ERR(speedbin_nvmem),
  61                                      "Could not get nvmem cell\n");
  62
  63         speedbin = nvmem_cell_read(speedbin_nvmem, &len);
  64         nvmem_cell_put(speedbin_nvmem);
  65         if (IS_ERR(speedbin))
  66                 return PTR_ERR(speedbin);
  67
  68         efuse_value = (*speedbin >> NVMEM_SHIFT) & NVMEM_MASK;
  69
  70         /*
  71          * We treat unexpected efuse values as if the SoC was from
  72          * the slowest bin. Expected efuse values are 1-3, slowest
  73          * to fastest.
  74          */
  75         if (efuse_value >= 1 && efuse_value <= 3)
  76                 *versions = efuse_value - 1;
  77         else
  78                 *versions = 0;
  79
  80         kfree(speedbin);
  81         return 0;
  82 };
  83
  84 static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev)
  85 {
  86         int *opp_tokens;
  87         char name[MAX_NAME_LEN];
  88         unsigned int cpu;
  89         u32 speed = 0;
  90         int ret;
  91
  92         opp_tokens = kcalloc(num_possible_cpus(), sizeof(*opp_tokens),
  93                              GFP_KERNEL);
  94         if (!opp_tokens)
  95                 return -ENOMEM;
  96
  97         ret = sun50i_cpufreq_get_efuse(&speed);
  98         if (ret) {
  99                 kfree(opp_tokens);
 100                 return ret;
 101         }
 102
 103         snprintf(name, MAX_NAME_LEN, "speed%d", speed);
 104
 105         for_each_possible_cpu(cpu) {
 106                 struct device *cpu_dev = get_cpu_device(cpu);
 107
 108                 if (!cpu_dev) {
 109                         ret = -ENODEV;
 110                         goto free_opp;
 111                 }
 112
 113                 opp_tokens[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name);
 114                 if (opp_tokens[cpu] < 0) {
 115                         ret = opp_tokens[cpu];
 116                         pr_err("Failed to set prop name\n");
 117                         goto free_opp;
 118                 }
 119         }
 120
 121         cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1,
 122                                                           NULL, 0);
 123         if (!IS_ERR(cpufreq_dt_pdev)) {
 124                 platform_set_drvdata(pdev, opp_tokens);
 125                 return 0;
 126         }
 127
 128         ret = PTR_ERR(cpufreq_dt_pdev);
 129         pr_err("Failed to register platform device\n");
 130
 131 free_opp:
 132         for_each_possible_cpu(cpu)
 133                 dev_pm_opp_put_prop_name(opp_tokens[cpu]);
 134         kfree(opp_tokens);
 135
 136         return ret;
 137 }
 138
 139 static int sun50i_cpufreq_nvmem_remove(struct platform_device *pdev)
 140 {
 141         int *opp_tokens = platform_get_drvdata(pdev);
 142         unsigned int cpu;
 143
 144         platform_device_unregister(cpufreq_dt_pdev);
 145
 146         for_each_possible_cpu(cpu)
 147                 dev_pm_opp_put_prop_name(opp_tokens[cpu]);
 148
 149         kfree(opp_tokens);
 150
 151         return 0;
 152 }
 153
 154 static struct platform_driver sun50i_cpufreq_driver = {
 155         .probe = sun50i_cpufreq_nvmem_probe,
 156         .remove = sun50i_cpufreq_nvmem_remove,
 157         .driver = {
 158                 .name = "sun50i-cpufreq-nvmem",
 159         },
 160 };
 161
 162 static const struct of_device_id sun50i_cpufreq_match_list[] = {
 163         { .compatible = "allwinner,sun50i-h6" },
 164         {}
 165 };
 166 MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list);
 167
 168 static const struct of_device_id *sun50i_cpufreq_match_node(void)
 169 {
 170         const struct of_device_id *match;
 171         struct device_node *np;
 172
 173         np = of_find_node_by_path("/");
 174         match = of_match_node(sun50i_cpufreq_match_list, np);
 175         of_node_put(np);
 176
 177         return match;
 178 }
 179
 180 /*
 181  * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER,
 182  * all the real activity is done in the probe, which may be defered as well.
 183  * The init here is only registering the driver and the platform device.
 184  */
 185 static int __init sun50i_cpufreq_init(void)
 186 {
 187         const struct of_device_id *match;
 188         int ret;
 189
 190         match = sun50i_cpufreq_match_node();
 191         if (!match)
 192                 return -ENODEV;
 193
 194         ret = platform_driver_register(&sun50i_cpufreq_driver);
 195         if (unlikely(ret < 0))
 196                 return ret;
 197
 198         sun50i_cpufreq_pdev =
 199                 platform_device_register_simple("sun50i-cpufreq-nvmem",
 200                                                 -1, NULL, 0);
 201         ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev);
 202         if (ret == 0)
 203                 return 0;
 204
 205         platform_driver_unregister(&sun50i_cpufreq_driver);
 206         return ret;
 207 }
 208 module_init(sun50i_cpufreq_init);
 209
 210 static void __exit sun50i_cpufreq_exit(void)
 211 {
 212         platform_device_unregister(sun50i_cpufreq_pdev);
 213         platform_driver_unregister(&sun50i_cpufreq_driver);
 214 }
 215 module_exit(sun50i_cpufreq_exit);
 216
 217 MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver");
 218 MODULE_LICENSE("GPL v2");