1 /* 2 * linux/drivers/devfreq/governor_passive.c 3 * 4 * Copyright (C) 2016 Samsung Electronics 5 * Author: Chanwoo Choi <cw00.choi@samsung.com> 6 * Author: MyungJoo Ham <myungjoo.ham@samsung.com> 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License version 2 as 10 * published by the Free Software Foundation. 11 */ 12 13 #include <linux/module.h> 14 #include <linux/device.h> 15 #include <linux/devfreq.h> 16 #include "governor.h" 17 18 static int devfreq_passive_get_target_freq(struct devfreq *devfreq, 19 unsigned long *freq) 20 { 21 struct devfreq_passive_data *p_data 22 = (struct devfreq_passive_data *)devfreq->data; 23 struct devfreq *parent_devfreq = (struct devfreq *)p_data->parent; 24 unsigned long child_freq = ULONG_MAX; 25 struct dev_pm_opp *opp; 26 int i, count, ret = 0; 27 28 /* 29 * If the devfreq device with passive governor has the specific method 30 * to determine the next frequency, should use the get_target_freq() 31 * of struct devfreq_passive_data. 32 */ 33 if (p_data->get_target_freq) { 34 ret = p_data->get_target_freq(devfreq, freq); 35 goto out; 36 } 37 38 /* 39 * If the parent and passive devfreq device uses the OPP table, 40 * get the next frequency by using the OPP table. 41 */ 42 43 /* 44 * - parent devfreq device uses the governors except for passive. 45 * - passive devfreq device uses the passive governor. 46 * 47 * Each devfreq has the OPP table. After deciding the new frequency 48 * from the governor of parent devfreq device, the passive governor 49 * need to get the index of new frequency on OPP table of parent 50 * device. And then the index is used for getting the suitable 51 * new frequency for passive devfreq device. 52 */ 53 if (!devfreq->profile || !devfreq->profile->freq_table 54 || devfreq->profile->max_state <= 0) 55 return -EINVAL; 56 57 /* 58 * The passive governor have to get the correct frequency from OPP 59 * list of parent device. Because in this case, *freq is temporary 60 * value which is decided by ondemand governor. 61 */ 62 opp = devfreq_recommended_opp(parent_devfreq->dev.parent, freq, 0); 63 if (IS_ERR(opp)) { 64 ret = PTR_ERR(opp); 65 goto out; 66 } 67 68 dev_pm_opp_put(opp); 69 70 /* 71 * Get the OPP table's index of decided freqeuncy by governor 72 * of parent device. 73 */ 74 for (i = 0; i < parent_devfreq->profile->max_state; i++) 75 if (parent_devfreq->profile->freq_table[i] == *freq) 76 break; 77 78 if (i == parent_devfreq->profile->max_state) { 79 ret = -EINVAL; 80 goto out; 81 } 82 83 /* Get the suitable frequency by using index of parent device. */ 84 if (i < devfreq->profile->max_state) { 85 child_freq = devfreq->profile->freq_table[i]; 86 } else { 87 count = devfreq->profile->max_state; 88 child_freq = devfreq->profile->freq_table[count - 1]; 89 } 90 91 /* Return the suitable frequency for passive device. */ 92 *freq = child_freq; 93 94 out: 95 return ret; 96 } 97 98 static int update_devfreq_passive(struct devfreq *devfreq, unsigned long freq) 99 { 100 int ret; 101 102 if (!devfreq->governor) 103 return -EINVAL; 104 105 mutex_lock_nested(&devfreq->lock, SINGLE_DEPTH_NESTING); 106 107 ret = devfreq->governor->get_target_freq(devfreq, &freq); 108 if (ret < 0) 109 goto out; 110 111 ret = devfreq->profile->target(devfreq->dev.parent, &freq, 0); 112 if (ret < 0) 113 goto out; 114 115 if (devfreq->profile->freq_table 116 && (devfreq_update_status(devfreq, freq))) 117 dev_err(&devfreq->dev, 118 "Couldn't update frequency transition information.\n"); 119 120 devfreq->previous_freq = freq; 121 122 out: 123 mutex_unlock(&devfreq->lock); 124 125 return 0; 126 } 127 128 static int devfreq_passive_notifier_call(struct notifier_block *nb, 129 unsigned long event, void *ptr) 130 { 131 struct devfreq_passive_data *data 132 = container_of(nb, struct devfreq_passive_data, nb); 133 struct devfreq *devfreq = (struct devfreq *)data->this; 134 struct devfreq *parent = (struct devfreq *)data->parent; 135 struct devfreq_freqs *freqs = (struct devfreq_freqs *)ptr; 136 unsigned long freq = freqs->new; 137 138 switch (event) { 139 case DEVFREQ_PRECHANGE: 140 if (parent->previous_freq > freq) 141 update_devfreq_passive(devfreq, freq); 142 break; 143 case DEVFREQ_POSTCHANGE: 144 if (parent->previous_freq < freq) 145 update_devfreq_passive(devfreq, freq); 146 break; 147 } 148 149 return NOTIFY_DONE; 150 } 151 152 static int devfreq_passive_event_handler(struct devfreq *devfreq, 153 unsigned int event, void *data) 154 { 155 struct device *dev = devfreq->dev.parent; 156 struct devfreq_passive_data *p_data 157 = (struct devfreq_passive_data *)devfreq->data; 158 struct devfreq *parent = (struct devfreq *)p_data->parent; 159 struct notifier_block *nb = &p_data->nb; 160 int ret = 0; 161 162 if (!parent) 163 return -EPROBE_DEFER; 164 165 switch (event) { 166 case DEVFREQ_GOV_START: 167 if (!p_data->this) 168 p_data->this = devfreq; 169 170 nb->notifier_call = devfreq_passive_notifier_call; 171 ret = devm_devfreq_register_notifier(dev, parent, nb, 172 DEVFREQ_TRANSITION_NOTIFIER); 173 break; 174 case DEVFREQ_GOV_STOP: 175 devm_devfreq_unregister_notifier(dev, parent, nb, 176 DEVFREQ_TRANSITION_NOTIFIER); 177 break; 178 default: 179 break; 180 } 181 182 return ret; 183 } 184 185 static struct devfreq_governor devfreq_passive = { 186 .name = "passive", 187 .immutable = 1, 188 .get_target_freq = devfreq_passive_get_target_freq, 189 .event_handler = devfreq_passive_event_handler, 190 }; 191 192 static int __init devfreq_passive_init(void) 193 { 194 return devfreq_add_governor(&devfreq_passive); 195 } 196 subsys_initcall(devfreq_passive_init); 197 198 static void __exit devfreq_passive_exit(void) 199 { 200 int ret; 201 202 ret = devfreq_remove_governor(&devfreq_passive); 203 if (ret) 204 pr_err("%s: failed remove governor %d\n", __func__, ret); 205 } 206 module_exit(devfreq_passive_exit); 207 208 MODULE_AUTHOR("Chanwoo Choi <cw00.choi@samsung.com>"); 209 MODULE_AUTHOR("MyungJoo Ham <myungjoo.ham@samsung.com>"); 210 MODULE_DESCRIPTION("DEVFREQ Passive governor"); 211 MODULE_LICENSE("GPL v2"); 212