drivers/soc/samsung/exynos-regulator-coupler.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (c) 2020 Samsung Electronics Co., Ltd.
   4  *            http://www.samsung.com/
   5  * Author: Marek Szyprowski <m.szyprowski@samsung.com>
   6  *
   7  * Simplified generic voltage coupler from regulator core.c
   8  * The main difference is that it keeps current regulator voltage
   9  * if consumers didn't apply their constraints yet.
  10  */
  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 static int regulator_get_optimal_voltage(struct regulator_dev *rdev,
  20                                          int *current_uV,
  21                                          int *min_uV, int *max_uV,
  22                                          suspend_state_t state)
  23 {
  24         struct coupling_desc *c_desc = &rdev->coupling_desc;
  25         struct regulator_dev **c_rdevs = c_desc->coupled_rdevs;
  26         struct regulation_constraints *constraints = rdev->constraints;
  27         int desired_min_uV = 0, desired_max_uV = INT_MAX;
  28         int max_current_uV = 0, min_current_uV = INT_MAX;
  29         int highest_min_uV = 0, target_uV, possible_uV;
  30         int i, ret, max_spread, n_coupled = c_desc->n_coupled;
  31         bool done;
  32
  33         *current_uV = -1;
  34
  35         /* Find highest min desired voltage */
  36         for (i = 0; i < n_coupled; i++) {
  37                 int tmp_min = 0;
  38                 int tmp_max = INT_MAX;
  39
  40                 lockdep_assert_held_once(&c_rdevs[i]->mutex.base);
  41
  42                 ret = regulator_check_consumers(c_rdevs[i],
  43                                                 &tmp_min,
  44                                                 &tmp_max, state);
  45                 if (ret < 0)
  46                         return ret;
  47
  48                 if (tmp_min == 0) {
  49                         ret = regulator_get_voltage_rdev(c_rdevs[i]);
  50                         if (ret < 0)
  51                                 return ret;
  52                         tmp_min = ret;
  53                 }
  54
  55                 /* apply constraints */
  56                 ret = regulator_check_voltage(c_rdevs[i], &tmp_min, &tmp_max);
  57                 if (ret < 0)
  58                         return ret;
  59
  60                 highest_min_uV = max(highest_min_uV, tmp_min);
  61
  62                 if (i == 0) {
  63                         desired_min_uV = tmp_min;
  64                         desired_max_uV = tmp_max;
  65                 }
  66         }
  67
  68         max_spread = constraints->max_spread[0];
  69
  70         /*
  71          * Let target_uV be equal to the desired one if possible.
  72          * If not, set it to minimum voltage, allowed by other coupled
  73          * regulators.
  74          */
  75         target_uV = max(desired_min_uV, highest_min_uV - max_spread);
  76
  77         /*
  78          * Find min and max voltages, which currently aren't violating
  79          * max_spread.
  80          */
  81         for (i = 1; i < n_coupled; i++) {
  82                 int tmp_act;
  83
  84                 tmp_act = regulator_get_voltage_rdev(c_rdevs[i]);
  85                 if (tmp_act < 0)
  86                         return tmp_act;
  87
  88                 min_current_uV = min(tmp_act, min_current_uV);
  89                 max_current_uV = max(tmp_act, max_current_uV);
  90         }
  91
  92         /*
  93          * Correct target voltage, so as it currently isn't
  94          * violating max_spread
  95          */
  96         possible_uV = max(target_uV, max_current_uV - max_spread);
  97         possible_uV = min(possible_uV, min_current_uV + max_spread);
  98
  99         if (possible_uV > desired_max_uV)
 100                 return -EINVAL;
 101
 102         done = (possible_uV == target_uV);
 103         desired_min_uV = possible_uV;
 104
 105         /* Set current_uV if wasn't done earlier in the code and if necessary */
 106         if (*current_uV == -1) {
 107                 ret = regulator_get_voltage_rdev(rdev);
 108                 if (ret < 0)
 109                         return ret;
 110                 *current_uV = ret;
 111         }
 112
 113         *min_uV = desired_min_uV;
 114         *max_uV = desired_max_uV;
 115
 116         return done;
 117 }
 118
 119 static int exynos_coupler_balance_voltage(struct regulator_coupler *coupler,
 120                                           struct regulator_dev *rdev,
 121                                           suspend_state_t state)
 122 {
 123         struct regulator_dev **c_rdevs;
 124         struct regulator_dev *best_rdev;
 125         struct coupling_desc *c_desc = &rdev->coupling_desc;
 126         int i, ret, n_coupled, best_min_uV, best_max_uV, best_c_rdev;
 127         unsigned int delta, best_delta;
 128         unsigned long c_rdev_done = 0;
 129         bool best_c_rdev_done;
 130
 131         c_rdevs = c_desc->coupled_rdevs;
 132         n_coupled = c_desc->n_coupled;
 133
 134         /*
 135          * Find the best possible voltage change on each loop. Leave the loop
 136          * if there isn't any possible change.
 137          */
 138         do {
 139                 best_c_rdev_done = false;
 140                 best_delta = 0;
 141                 best_min_uV = 0;
 142                 best_max_uV = 0;
 143                 best_c_rdev = 0;
 144                 best_rdev = NULL;
 145
 146                 /*
 147                  * Find highest difference between optimal voltage
 148                  * and current voltage.
 149                  */
 150                 for (i = 0; i < n_coupled; i++) {
 151                         /*
 152                          * optimal_uV is the best voltage that can be set for
 153                          * i-th regulator at the moment without violating
 154                          * max_spread constraint in order to balance
 155                          * the coupled voltages.
 156                          */
 157                         int optimal_uV = 0, optimal_max_uV = 0, current_uV = 0;
 158
 159                         if (test_bit(i, &c_rdev_done))
 160                                 continue;
 161
 162                         ret = regulator_get_optimal_voltage(c_rdevs[i],
 163                                                             &current_uV,
 164                                                             &optimal_uV,
 165                                                             &optimal_max_uV,
 166                                                             state);
 167                         if (ret < 0)
 168                                 goto out;
 169
 170                         delta = abs(optimal_uV - current_uV);
 171
 172                         if (delta && best_delta <= delta) {
 173                                 best_c_rdev_done = ret;
 174                                 best_delta = delta;
 175                                 best_rdev = c_rdevs[i];
 176                                 best_min_uV = optimal_uV;
 177                                 best_max_uV = optimal_max_uV;
 178                                 best_c_rdev = i;
 179                         }
 180                 }
 181
 182                 /* Nothing to change, return successfully */
 183                 if (!best_rdev) {
 184                         ret = 0;
 185                         goto out;
 186                 }
 187
 188                 ret = regulator_set_voltage_rdev(best_rdev, best_min_uV,
 189                                                  best_max_uV, state);
 190
 191                 if (ret < 0)
 192                         goto out;
 193
 194                 if (best_c_rdev_done)
 195                         set_bit(best_c_rdev, &c_rdev_done);
 196
 197         } while (n_coupled > 1);
 198
 199 out:
 200         return ret;
 201 }
 202
 203 static int exynos_coupler_attach(struct regulator_coupler *coupler,
 204                                  struct regulator_dev *rdev)
 205 {
 206         return 0;
 207 }
 208
 209 static struct regulator_coupler exynos_coupler = {
 210         .attach_regulator = exynos_coupler_attach,
 211         .balance_voltage  = exynos_coupler_balance_voltage,
 212 };
 213
 214 static int __init exynos_coupler_init(void)
 215 {
 216         if (!of_machine_is_compatible("samsung,exynos5800"))
 217                 return 0;
 218
 219         return regulator_coupler_register(&exynos_coupler);
 220 }
 221 arch_initcall(exynos_coupler_init);