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