1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * linux/drivers/devfreq/governor_passive.c 4 * 5 * Copyright (C) 2016 Samsung Electronics 6 * Author: Chanwoo Choi <cw00.choi@samsung.com> 7 * Author: MyungJoo Ham <myungjoo.ham@samsung.com> 8 */ 9 10 #include <linux/module.h> 11 #include <linux/device.h> 12 #include <linux/devfreq.h> 13 #include "governor.h" 14 15 static int devfreq_passive_get_target_freq(struct devfreq *devfreq, 16 unsigned long *freq) 17 { 18 struct devfreq_passive_data *p_data 19 = (struct devfreq_passive_data *)devfreq->data; 20 struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent; 21 unsigned long child_freq = ULONG_MAX; 22 struct dev_pm_opp *opp; 23 int i, count, ret = 0; 24 25 /* 26 * If the devfreq device with passive governor has the specific method 27 * to determine the next frequency, should use the get_target_freq() 28 * of struct devfreq_passive_data. 29 */ 30 if (p_data->get_target_freq) { 31 ret = p_data->get_target_freq(devfreq, freq); 32 goto out; 33 } 34 35 /* 36 * If the parent and passive devfreq device uses the OPP table, 37 * get the next frequency by using the OPP table. 38 */ 39 40 /* 41 * - parent devfreq device uses the governors except for passive. 42 * - passive devfreq device uses the passive governor. 43 * 44 * Each devfreq has the OPP table. After deciding the new frequency 45 * from the governor of parent devfreq device, the passive governor 46 * need to get the index of new frequency on OPP table of parent 47 * device. And then the index is used for getting the suitable 48 * new frequency for passive devfreq device. 49 */ 50 if (!devfreq->profile || !devfreq->profile->freq_table 51 || devfreq->profile->max_state <= 0) 52 return -EINVAL; 53 54 /* 55 * The passive governor have to get the correct frequency from OPP 56 * list of parent device. Because in this case, *freq is temporary 57 * value which is decided by ondemand governor. 58 */ 59 opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, 0); 60 if (IS_ERR(opp)) { 61 ret = PTR_ERR(opp); 62 goto out; 63 } 64 65 dev_pm_opp_put(opp); 66 67 /* 68 * Get the OPP table's index of decided freqeuncy by governor 69 * of parent device. 70 */ 71 for (i = 0; i < parent_devfreq->profile->max_state; i++) 72 if (parent_devfreq->profile->freq_table[i] == *freq) 73 break; 74 75 if (i == parent_devfreq->profile->max_state) { 76 ret = -EINVAL; 77 goto out; 78 } 79 80 /* Get the suitable frequency by using index of parent device. */ 81 if (i < devfreq->profile->max_state) { 82 child_freq = devfreq->profile->freq_table[i]; 83 } else { 84 count = devfreq->profile->max_state; 85 child_freq = devfreq->profile->freq_table[count - 1]; 86 } 87 88 /* Return the suitable frequency for passive device. */ 89 *freq = child_freq; 90 91 out: 92 return ret; 93 } 94 95 static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq) 96 { 97 int ret; 98 99 if (!devfreq->governor) 100 return -EINVAL; 101 102 mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING); 103 104 ret = devfreq->governor->get_target_freq(devfreq, &freq); 105 if (ret < 0) 106 goto out; 107 108 ret = devfreq->profile->target(devfreq->dev.parent, &freq, 0); 109 if (ret < 0) 110 goto out; 111 112 if (devfreq->profile->freq_table 113 && (devfreq_update_status(devfreq, freq))) 114 dev_err(&devfreq->dev, 115 "Couldn't update frequency transition information.\n"); 116 117 devfreq->previous_freq = freq; 118 119 out: 120 mutex_unlock(&devfreq->lock); 121 122 return 0; 123 } 124 125 static int devfreq_passive_notifier_call(struct notifier_block *nb, 126 unsigned long event, void *ptr) 127 { 128 struct devfreq_passive_data *data 129 = container_of(nb, struct devfreq_passive_data, nb); 130 struct devfreq *devfreq = (struct devfreq *)data->this; 131 struct devfreq *parent = (struct devfreq *)data->parent; 132 struct devfreq_freqs *freqs = (struct devfreq_freqs *)ptr; 133 unsigned long freq = freqs->new; 134 135 switch (event) { 136 case DEVFREQ_PRECHANGE: 137 if (parent->previous_freq > freq) 138 update_devfreq_passive(devfreq, freq); 139 break; 140 case DEVFREQ_POSTCHANGE: 141 if (parent->previous_freq < freq) 142 update_devfreq_passive(devfreq, freq); 143 break; 144 } 145 146 return NOTIFY_DONE; 147 } 148 149 static int devfreq_passive_event_handler(struct devfreq *devfreq, 150 unsigned int event, void *data) 151 { 152 struct devfreq_passive_data *p_data 153 = (struct devfreq_passive_data *)devfreq->data; 154 struct devfreq *parent = (struct devfreq *)p_data->parent; 155 struct notifier_block *nb = &p_data->nb; 156 int ret = 0; 157 158 if (!parent) 159 return -EPROBE_DEFER; 160 161 switch (event) { 162 case DEVFREQ_GOV_START: 163 if (!p_data->this) 164 p_data->this = devfreq; 165 166 nb->notifier_call = devfreq_passive_notifier_call; 167 ret = devfreq_register_notifier(parent, nb, 168 DEVFREQ_TRANSITION_NOTIFIER); 169 break; 170 case DEVFREQ_GOV_STOP: 171 WARN_ON(devfreq_unregister_notifier(parent, nb, 172 DEVFREQ_TRANSITION_NOTIFIER)); 173 break; 174 default: 175 break; 176 } 177 178 return ret; 179 } 180 181 static struct devfreq_governor devfreq_passive = { 182 .name = DEVFREQ_GOV_PASSIVE, 183 .immutable = 1, 184 .get_target_freq = devfreq_passive_get_target_freq, 185 .event_handler = devfreq_passive_event_handler, 186 }; 187 188 static int __init devfreq_passive_init(void) 189 { 190 return devfreq_add_governor(&devfreq_passive); 191 } 192 subsys_initcall(devfreq_passive_init); 193 194 static void __exit devfreq_passive_exit(void) 195 { 196 int ret; 197 198 ret = devfreq_remove_governor(&devfreq_passive); 199 if (ret) 200 pr_err("%s: failed remove governor %d\n", __func__, ret); 201 } 202 module_exit(devfreq_passive_exit); 203 204 MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>"); 205 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); 206 MODULE_DESCRIPTION("DEVFREQ Passive governor"); 207 MODULE_LICENSE("GPL v2"); 208