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, *p_opp; 23 int i, count; 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 return p_data->get_target_freq(devfreq, freq); 32 33 /* 34 * If the parent and passive devfreq device uses the OPP table, 35 * get the next frequency by using the OPP table. 36 */ 37 38 /* 39 * - parent devfreq device uses the governors except for passive. 40 * - passive devfreq device uses the passive governor. 41 * 42 * Each devfreq has the OPP table. After deciding the new frequency 43 * from the governor of parent devfreq device, the passive governor 44 * need to get the index of new frequency on OPP table of parent 45 * device. And then the index is used for getting the suitable 46 * new frequency for passive devfreq device. 47 */ 48 if (!devfreq->profile || !devfreq->profile->freq_table 49 || devfreq->profile->max_state <= 0) 50 return -EINVAL; 51 52 /* 53 * The passive governor have to get the correct frequency from OPP 54 * list of parent device. Because in this case, *freq is temporary 55 * value which is decided by ondemand governor. 56 */ 57 if (devfreq->opp_table && parent_devfreq->opp_table) { 58 p_opp = devfreq_recommended_opp(parent_devfreq->dev.parent, 59 freq, 0); 60 if (IS_ERR(p_opp)) 61 return PTR_ERR(p_opp); 62 63 opp = dev_pm_opp_xlate_required_opp(parent_devfreq->opp_table, 64 devfreq->opp_table, p_opp); 65 dev_pm_opp_put(p_opp); 66 67 if (IS_ERR(opp)) 68 goto no_required_opp; 69 70 *freq = dev_pm_opp_get_freq(opp); 71 dev_pm_opp_put(opp); 72 73 return 0; 74 } 75 76 no_required_opp: 77 /* 78 * Get the OPP table's index of decided frequency by governor 79 * of parent device. 80 */ 81 for (i = 0; i < parent_devfreq->profile->max_state; i++) 82 if (parent_devfreq->profile->freq_table[i] == *freq) 83 break; 84 85 if (i == parent_devfreq->profile->max_state) 86 return -EINVAL; 87 88 /* Get the suitable frequency by using index of parent device. */ 89 if (i < devfreq->profile->max_state) { 90 child_freq = devfreq->profile->freq_table[i]; 91 } else { 92 count = devfreq->profile->max_state; 93 child_freq = devfreq->profile->freq_table[count - 1]; 94 } 95 96 /* Return the suitable frequency for passive device. */ 97 *freq = child_freq; 98 99 return 0; 100 } 101 102 static int devfreq_passive_notifier_call(struct notifier_block *nb, 103 unsigned long event, void *ptr) 104 { 105 struct devfreq_passive_data *data 106 = container_of(nb, struct devfreq_passive_data, nb); 107 struct devfreq *devfreq = (struct devfreq *)data->this; 108 struct devfreq *parent = (struct devfreq *)data->parent; 109 struct devfreq_freqs *freqs = (struct devfreq_freqs *)ptr; 110 unsigned long freq = freqs->new; 111 int ret = 0; 112 113 mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING); 114 switch (event) { 115 case DEVFREQ_PRECHANGE: 116 if (parent->previous_freq > freq) 117 ret = devfreq_update_target(devfreq, freq); 118 119 break; 120 case DEVFREQ_POSTCHANGE: 121 if (parent->previous_freq < freq) 122 ret = devfreq_update_target(devfreq, freq); 123 break; 124 } 125 mutex_unlock(&devfreq->lock); 126 127 if (ret < 0) 128 dev_warn(&devfreq->dev, 129 "failed to update devfreq using passive governor\n"); 130 131 return NOTIFY_DONE; 132 } 133 134 static int devfreq_passive_event_handler(struct devfreq *devfreq, 135 unsigned int event, void *data) 136 { 137 struct devfreq_passive_data *p_data 138 = (struct devfreq_passive_data *)devfreq->data; 139 struct devfreq *parent = (struct devfreq *)p_data->parent; 140 struct notifier_block *nb = &p_data->nb; 141 int ret = 0; 142 143 if (!parent) 144 return -EPROBE_DEFER; 145 146 switch (event) { 147 case DEVFREQ_GOV_START: 148 if (!p_data->this) 149 p_data->this = devfreq; 150 151 nb->notifier_call = devfreq_passive_notifier_call; 152 ret = devfreq_register_notifier(parent, nb, 153 DEVFREQ_TRANSITION_NOTIFIER); 154 break; 155 case DEVFREQ_GOV_STOP: 156 WARN_ON(devfreq_unregister_notifier(parent, nb, 157 DEVFREQ_TRANSITION_NOTIFIER)); 158 break; 159 default: 160 break; 161 } 162 163 return ret; 164 } 165 166 static struct devfreq_governor devfreq_passive = { 167 .name = DEVFREQ_GOV_PASSIVE, 168 .flags = DEVFREQ_GOV_FLAG_IMMUTABLE, 169 .get_target_freq = devfreq_passive_get_target_freq, 170 .event_handler = devfreq_passive_event_handler, 171 }; 172 173 static int __init devfreq_passive_init(void) 174 { 175 return devfreq_add_governor(&devfreq_passive); 176 } 177 subsys_initcall(devfreq_passive_init); 178 179 static void __exit devfreq_passive_exit(void) 180 { 181 int ret; 182 183 ret = devfreq_remove_governor(&devfreq_passive); 184 if (ret) 185 pr_err("%s: failed remove governor %d\n", __func__, ret); 186 } 187 module_exit(devfreq_passive_exit); 188 189 MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>"); 190 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); 191 MODULE_DESCRIPTION("DEVFREQ Passive governor"); 192 MODULE_LICENSE("GPL v2"); 193