1 // SPDX-License-Identifier: GPL-2.0+ 2 /* 3 * Voltage regulators coupler for NVIDIA Tegra30 4 * Copyright (C) 2019 GRATE-DRIVER project 5 * 6 * Voltage constraints borrowed from downstream kernel sources 7 * Copyright (C) 2010-2011 NVIDIA Corporation 8 */ 9 10 #define pr_fmt(fmt) "tegra voltage-coupler: " fmt 11 12 #include <linux/init.h> 13 #include <linux/kernel.h> 14 #include <linux/of.h> 15 #include <linux/regulator/coupler.h> 16 #include <linux/regulator/driver.h> 17 #include <linux/regulator/machine.h> 18 19 #include <soc/tegra/fuse.h> 20 21 struct tegra_regulator_coupler { 22 struct regulator_coupler coupler; 23 struct regulator_dev *core_rdev; 24 struct regulator_dev *cpu_rdev; 25 int core_min_uV; 26 }; 27 28 static inline struct tegra_regulator_coupler * 29 to_tegra_coupler(struct regulator_coupler *coupler) 30 { 31 return container_of(coupler, struct tegra_regulator_coupler, coupler); 32 } 33 34 static int tegra30_core_limit(struct tegra_regulator_coupler *tegra, 35 struct regulator_dev *core_rdev) 36 { 37 int core_min_uV = 0; 38 int core_max_uV; 39 int core_cur_uV; 40 int err; 41 42 if (tegra->core_min_uV > 0) 43 return tegra->core_min_uV; 44 45 core_cur_uV = regulator_get_voltage_rdev(core_rdev); 46 if (core_cur_uV < 0) 47 return core_cur_uV; 48 49 core_max_uV = max(core_cur_uV, 1200000); 50 51 err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV); 52 if (err) 53 return err; 54 55 /* 56 * Limit minimum CORE voltage to a value left from bootloader or, 57 * if it's unreasonably low value, to the most common 1.2v or to 58 * whatever maximum value defined via board's device-tree. 59 */ 60 tegra->core_min_uV = core_max_uV; 61 62 pr_info("core minimum voltage limited to %duV\n", tegra->core_min_uV); 63 64 return tegra->core_min_uV; 65 } 66 67 static int tegra30_core_cpu_limit(int cpu_uV) 68 { 69 if (cpu_uV < 800000) 70 return 950000; 71 72 if (cpu_uV < 900000) 73 return 1000000; 74 75 if (cpu_uV < 1000000) 76 return 1100000; 77 78 if (cpu_uV < 1100000) 79 return 1200000; 80 81 if (cpu_uV < 1250000) { 82 switch (tegra_sku_info.cpu_speedo_id) { 83 case 0 ... 1: 84 case 4: 85 case 7 ... 8: 86 return 1200000; 87 88 default: 89 return 1300000; 90 } 91 } 92 93 return -EINVAL; 94 } 95 96 static int tegra30_voltage_update(struct tegra_regulator_coupler *tegra, 97 struct regulator_dev *cpu_rdev, 98 struct regulator_dev *core_rdev) 99 { 100 int core_min_uV, core_max_uV = INT_MAX; 101 int cpu_min_uV, cpu_max_uV = INT_MAX; 102 int cpu_min_uV_consumers = 0; 103 int core_min_limited_uV; 104 int core_target_uV; 105 int cpu_target_uV; 106 int core_max_step; 107 int cpu_max_step; 108 int max_spread; 109 int core_uV; 110 int cpu_uV; 111 int err; 112 113 /* 114 * CPU voltage should not got lower than 300mV from the CORE. 115 * CPU voltage should stay below the CORE by 100mV+, depending 116 * by the CORE voltage. This applies to all Tegra30 SoC's. 117 */ 118 max_spread = cpu_rdev->constraints->max_spread[0]; 119 cpu_max_step = cpu_rdev->constraints->max_uV_step; 120 core_max_step = core_rdev->constraints->max_uV_step; 121 122 if (!max_spread) { 123 pr_err_once("cpu-core max-spread is undefined in device-tree\n"); 124 max_spread = 300000; 125 } 126 127 if (!cpu_max_step) { 128 pr_err_once("cpu max-step is undefined in device-tree\n"); 129 cpu_max_step = 150000; 130 } 131 132 if (!core_max_step) { 133 pr_err_once("core max-step is undefined in device-tree\n"); 134 core_max_step = 150000; 135 } 136 137 /* 138 * The CORE voltage scaling is currently not hooked up in drivers, 139 * hence we will limit the minimum CORE voltage to a reasonable value. 140 * This should be good enough for the time being. 141 */ 142 core_min_uV = tegra30_core_limit(tegra, core_rdev); 143 if (core_min_uV < 0) 144 return core_min_uV; 145 146 err = regulator_check_consumers(core_rdev, &core_min_uV, &core_max_uV, 147 PM_SUSPEND_ON); 148 if (err) 149 return err; 150 151 core_uV = regulator_get_voltage_rdev(core_rdev); 152 if (core_uV < 0) 153 return core_uV; 154 155 cpu_min_uV = core_min_uV - max_spread; 156 157 err = regulator_check_consumers(cpu_rdev, &cpu_min_uV, &cpu_max_uV, 158 PM_SUSPEND_ON); 159 if (err) 160 return err; 161 162 err = regulator_check_consumers(cpu_rdev, &cpu_min_uV_consumers, 163 &cpu_max_uV, PM_SUSPEND_ON); 164 if (err) 165 return err; 166 167 err = regulator_check_voltage(cpu_rdev, &cpu_min_uV, &cpu_max_uV); 168 if (err) 169 return err; 170 171 cpu_uV = regulator_get_voltage_rdev(cpu_rdev); 172 if (cpu_uV < 0) 173 return cpu_uV; 174 175 /* 176 * CPU's regulator may not have any consumers, hence the voltage 177 * must not be changed in that case because CPU simply won't 178 * survive the voltage drop if it's running on a higher frequency. 179 */ 180 if (!cpu_min_uV_consumers) 181 cpu_min_uV = cpu_uV; 182 183 /* 184 * Bootloader shall set up voltages correctly, but if it 185 * happens that there is a violation, then try to fix it 186 * at first. 187 */ 188 core_min_limited_uV = tegra30_core_cpu_limit(cpu_uV); 189 if (core_min_limited_uV < 0) 190 return core_min_limited_uV; 191 192 core_min_uV = max(core_min_uV, tegra30_core_cpu_limit(cpu_min_uV)); 193 194 err = regulator_check_voltage(core_rdev, &core_min_uV, &core_max_uV); 195 if (err) 196 return err; 197 198 if (core_min_limited_uV > core_uV) { 199 pr_err("core voltage constraint violated: %d %d %d\n", 200 core_uV, core_min_limited_uV, cpu_uV); 201 goto update_core; 202 } 203 204 while (cpu_uV != cpu_min_uV || core_uV != core_min_uV) { 205 if (cpu_uV < cpu_min_uV) { 206 cpu_target_uV = min(cpu_uV + cpu_max_step, cpu_min_uV); 207 } else { 208 cpu_target_uV = max(cpu_uV - cpu_max_step, cpu_min_uV); 209 cpu_target_uV = max(core_uV - max_spread, cpu_target_uV); 210 } 211 212 err = regulator_set_voltage_rdev(cpu_rdev, 213 cpu_target_uV, 214 cpu_max_uV, 215 PM_SUSPEND_ON); 216 if (err) 217 return err; 218 219 cpu_uV = cpu_target_uV; 220 update_core: 221 core_min_limited_uV = tegra30_core_cpu_limit(cpu_uV); 222 if (core_min_limited_uV < 0) 223 return core_min_limited_uV; 224 225 core_target_uV = max(core_min_limited_uV, core_min_uV); 226 227 if (core_uV < core_target_uV) { 228 core_target_uV = min(core_target_uV, core_uV + core_max_step); 229 core_target_uV = min(core_target_uV, cpu_uV + max_spread); 230 } else { 231 core_target_uV = max(core_target_uV, core_uV - core_max_step); 232 } 233 234 err = regulator_set_voltage_rdev(core_rdev, 235 core_target_uV, 236 core_max_uV, 237 PM_SUSPEND_ON); 238 if (err) 239 return err; 240 241 core_uV = core_target_uV; 242 } 243 244 return 0; 245 } 246 247 static int tegra30_regulator_balance_voltage(struct regulator_coupler *coupler, 248 struct regulator_dev *rdev, 249 suspend_state_t state) 250 { 251 struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler); 252 struct regulator_dev *core_rdev = tegra->core_rdev; 253 struct regulator_dev *cpu_rdev = tegra->cpu_rdev; 254 255 if ((core_rdev != rdev && cpu_rdev != rdev) || state != PM_SUSPEND_ON) { 256 pr_err("regulators are not coupled properly\n"); 257 return -EINVAL; 258 } 259 260 return tegra30_voltage_update(tegra, cpu_rdev, core_rdev); 261 } 262 263 static int tegra30_regulator_attach(struct regulator_coupler *coupler, 264 struct regulator_dev *rdev) 265 { 266 struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler); 267 struct device_node *np = rdev->dev.of_node; 268 269 if (of_property_read_bool(np, "nvidia,tegra-core-regulator") && 270 !tegra->core_rdev) { 271 tegra->core_rdev = rdev; 272 return 0; 273 } 274 275 if (of_property_read_bool(np, "nvidia,tegra-cpu-regulator") && 276 !tegra->cpu_rdev) { 277 tegra->cpu_rdev = rdev; 278 return 0; 279 } 280 281 return -EINVAL; 282 } 283 284 static int tegra30_regulator_detach(struct regulator_coupler *coupler, 285 struct regulator_dev *rdev) 286 { 287 struct tegra_regulator_coupler *tegra = to_tegra_coupler(coupler); 288 289 if (tegra->core_rdev == rdev) { 290 tegra->core_rdev = NULL; 291 return 0; 292 } 293 294 if (tegra->cpu_rdev == rdev) { 295 tegra->cpu_rdev = NULL; 296 return 0; 297 } 298 299 return -EINVAL; 300 } 301 302 static struct tegra_regulator_coupler tegra30_coupler = { 303 .coupler = { 304 .attach_regulator = tegra30_regulator_attach, 305 .detach_regulator = tegra30_regulator_detach, 306 .balance_voltage = tegra30_regulator_balance_voltage, 307 }, 308 }; 309 310 static int __init tegra_regulator_coupler_init(void) 311 { 312 if (!of_machine_is_compatible("nvidia,tegra30")) 313 return 0; 314 315 return regulator_coupler_register(&tegra30_coupler.coupler); 316 } 317 arch_initcall(tegra_regulator_coupler_init); 318