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 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 87 static int sun50i_cpufreq_nvmem_probe(struct platform_device *pdev) 88 { 89 int *opp_tokens; 90 char name[MAX_NAME_LEN]; 91 unsigned int cpu; 92 u32 speed = 0; 93 int ret; 94 95 opp_tokens = kcalloc(num_possible_cpus(), sizeof(*opp_tokens), 96 GFP_KERNEL); 97 if (!opp_tokens) 98 return -ENOMEM; 99 100 ret = sun50i_cpufreq_get_efuse(&speed); 101 if (ret) { 102 kfree(opp_tokens); 103 return ret; 104 } 105 106 snprintf(name, MAX_NAME_LEN, "speed%d", speed); 107 108 for_each_possible_cpu(cpu) { 109 struct device *cpu_dev = get_cpu_device(cpu); 110 111 if (!cpu_dev) { 112 ret = -ENODEV; 113 goto free_opp; 114 } 115 116 opp_tokens[cpu] = dev_pm_opp_set_prop_name(cpu_dev, name); 117 if (opp_tokens[cpu] < 0) { 118 ret = opp_tokens[cpu]; 119 pr_err("Failed to set prop name\n"); 120 goto free_opp; 121 } 122 } 123 124 cpufreq_dt_pdev = platform_device_register_simple("cpufreq-dt", -1, 125 NULL, 0); 126 if (!IS_ERR(cpufreq_dt_pdev)) { 127 platform_set_drvdata(pdev, opp_tokens); 128 return 0; 129 } 130 131 ret = PTR_ERR(cpufreq_dt_pdev); 132 pr_err("Failed to register platform device\n"); 133 134 free_opp: 135 for_each_possible_cpu(cpu) 136 dev_pm_opp_put_prop_name(opp_tokens[cpu]); 137 kfree(opp_tokens); 138 139 return ret; 140 } 141 142 static int sun50i_cpufreq_nvmem_remove(struct platform_device *pdev) 143 { 144 int *opp_tokens = platform_get_drvdata(pdev); 145 unsigned int cpu; 146 147 platform_device_unregister(cpufreq_dt_pdev); 148 149 for_each_possible_cpu(cpu) 150 dev_pm_opp_put_prop_name(opp_tokens[cpu]); 151 152 kfree(opp_tokens); 153 154 return 0; 155 } 156 157 static struct platform_driver sun50i_cpufreq_driver = { 158 .probe = sun50i_cpufreq_nvmem_probe, 159 .remove = sun50i_cpufreq_nvmem_remove, 160 .driver = { 161 .name = "sun50i-cpufreq-nvmem", 162 }, 163 }; 164 165 static const struct of_device_id sun50i_cpufreq_match_list[] = { 166 { .compatible = "allwinner,sun50i-h6" }, 167 {} 168 }; 169 MODULE_DEVICE_TABLE(of, sun50i_cpufreq_match_list); 170 171 static const struct of_device_id *sun50i_cpufreq_match_node(void) 172 { 173 const struct of_device_id *match; 174 struct device_node *np; 175 176 np = of_find_node_by_path("/"); 177 match = of_match_node(sun50i_cpufreq_match_list, np); 178 of_node_put(np); 179 180 return match; 181 } 182 183 /* 184 * Since the driver depends on nvmem drivers, which may return EPROBE_DEFER, 185 * all the real activity is done in the probe, which may be defered as well. 186 * The init here is only registering the driver and the platform device. 187 */ 188 static int __init sun50i_cpufreq_init(void) 189 { 190 const struct of_device_id *match; 191 int ret; 192 193 match = sun50i_cpufreq_match_node(); 194 if (!match) 195 return -ENODEV; 196 197 ret = platform_driver_register(&sun50i_cpufreq_driver); 198 if (unlikely(ret < 0)) 199 return ret; 200 201 sun50i_cpufreq_pdev = 202 platform_device_register_simple("sun50i-cpufreq-nvmem", 203 -1, NULL, 0); 204 ret = PTR_ERR_OR_ZERO(sun50i_cpufreq_pdev); 205 if (ret == 0) 206 return 0; 207 208 platform_driver_unregister(&sun50i_cpufreq_driver); 209 return ret; 210 } 211 module_init(sun50i_cpufreq_init); 212 213 static void __exit sun50i_cpufreq_exit(void) 214 { 215 platform_device_unregister(sun50i_cpufreq_pdev); 216 platform_driver_unregister(&sun50i_cpufreq_driver); 217 } 218 module_exit(sun50i_cpufreq_exit); 219 220 MODULE_DESCRIPTION("Sun50i-h6 cpufreq driver"); 221 MODULE_LICENSE("GPL v2"); 222