bus: ti-sysc: Fix watchdog quirk handling
[linux-2.6-microblaze.git] / drivers / devfreq / governor_passive.c
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");