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 void 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 } 152 153 static struct platform_driver sun50i_cpufreq_driver = { 154 .probe = sun50i_cpufreq_nvmem_probe, 155 .remove_new = sun50i_cpufreq_nvmem_remove, 156 .driver = { 157 .name = "sun50i-cpufreq-nvmem", 158 }, 159 }; 160 161 static const struct of_device_id sun50i_cpufreq_match_list[] = { 162 { .compatible = "allwinner,sun50i-h6" }, 163 {} 164 }; 165 MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list); 166 167 static const struct of_device_id *sun50i_cpufreq_match_node(void) 168 { 169 const struct of_device_id *match; 170 struct device_node *np; 171 172 np = of_find_node_by_path("/"); 173 match = of_match_node(sun50i_cpufreq_match_list, np); 174 of_node_put(np); 175 176 return match; 177 } 178 179 /* 180 * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER, 181 * all the real activity is done in the probe, which may be defered as well. 182 * The init here is only registering the driver and the platform device. 183 */ 184 static int __init sun50i_cpufreq_init(void) 185 { 186 const struct of_device_id *match; 187 int ret; 188 189 match = sun50i_cpufreq_match_node(); 190 if (!match) 191 return -ENODEV; 192 193 ret = platform_driver_register(&sun50i_cpufreq_driver); 194 if (unlikely(ret < 0)) 195 return ret; 196 197 sun50i_cpufreq_pdev = 198 platform_device_register_simple("sun50i-cpufreq-nvmem", 199 -1, NULL, 0); 200 ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev); 201 if (ret == 0) 202 return 0; 203 204 platform_driver_unregister(&sun50i_cpufreq_driver); 205 return ret; 206 } 207 module_init(sun50i_cpufreq_init); 208 209 static void __exit sun50i_cpufreq_exit(void) 210 { 211 platform_device_unregister(sun50i_cpufreq_pdev); 212 platform_driver_unregister(&sun50i_cpufreq_driver); 213 } 214 module_exit(sun50i_cpufreq_exit); 215 216 MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver"); 217 MODULE_LICENSE("GPL v2"); 218