1 | // SPDX-License-Identifier: GPL-2.0-only |
2 | /* |
3 | * linux/drivers/devfreq/governor_userspace.c |
4 | * |
5 | * Copyright (C) 2011 Samsung Electronics |
6 | * MyungJoo Ham <myungjoo.ham@samsung.com> |
7 | */ |
8 | |
9 | #include <linux/slab.h> |
10 | #include <linux/device.h> |
11 | #include <linux/devfreq.h> |
12 | #include <linux/pm.h> |
13 | #include <linux/mutex.h> |
14 | #include <linux/module.h> |
15 | #include "governor.h" |
16 | |
17 | struct userspace_data { |
18 | unsigned long user_frequency; |
19 | bool valid; |
20 | }; |
21 | |
22 | static int devfreq_userspace_func(struct devfreq *df, unsigned long *freq) |
23 | { |
24 | struct userspace_data *data = df->governor_data; |
25 | |
26 | if (data->valid) |
27 | *freq = data->user_frequency; |
28 | else |
29 | *freq = df->previous_freq; /* No user freq specified yet */ |
30 | |
31 | return 0; |
32 | } |
33 | |
34 | static ssize_t set_freq_store(struct device *dev, struct device_attribute *attr, |
35 | const char *buf, size_t count) |
36 | { |
37 | struct devfreq *devfreq = to_devfreq(dev); |
38 | struct userspace_data *data; |
39 | unsigned long wanted; |
40 | int err = 0; |
41 | |
42 | mutex_lock(&devfreq->lock); |
43 | data = devfreq->governor_data; |
44 | |
45 | sscanf(buf, "%lu" , &wanted); |
46 | data->user_frequency = wanted; |
47 | data->valid = true; |
48 | err = update_devfreq(devfreq); |
49 | if (err == 0) |
50 | err = count; |
51 | mutex_unlock(lock: &devfreq->lock); |
52 | return err; |
53 | } |
54 | |
55 | static ssize_t set_freq_show(struct device *dev, |
56 | struct device_attribute *attr, char *buf) |
57 | { |
58 | struct devfreq *devfreq = to_devfreq(dev); |
59 | struct userspace_data *data; |
60 | int err = 0; |
61 | |
62 | mutex_lock(&devfreq->lock); |
63 | data = devfreq->governor_data; |
64 | |
65 | if (data->valid) |
66 | err = sprintf(buf, fmt: "%lu\n" , data->user_frequency); |
67 | else |
68 | err = sprintf(buf, fmt: "undefined\n" ); |
69 | mutex_unlock(lock: &devfreq->lock); |
70 | return err; |
71 | } |
72 | |
73 | static DEVICE_ATTR_RW(set_freq); |
74 | static struct attribute *dev_entries[] = { |
75 | &dev_attr_set_freq.attr, |
76 | NULL, |
77 | }; |
78 | static const struct attribute_group dev_attr_group = { |
79 | .name = DEVFREQ_GOV_USERSPACE, |
80 | .attrs = dev_entries, |
81 | }; |
82 | |
83 | static int userspace_init(struct devfreq *devfreq) |
84 | { |
85 | int err = 0; |
86 | struct userspace_data *data = kzalloc(size: sizeof(struct userspace_data), |
87 | GFP_KERNEL); |
88 | |
89 | if (!data) { |
90 | err = -ENOMEM; |
91 | goto out; |
92 | } |
93 | data->valid = false; |
94 | devfreq->governor_data = data; |
95 | |
96 | err = sysfs_create_group(kobj: &devfreq->dev.kobj, grp: &dev_attr_group); |
97 | out: |
98 | return err; |
99 | } |
100 | |
101 | static void userspace_exit(struct devfreq *devfreq) |
102 | { |
103 | /* |
104 | * Remove the sysfs entry, unless this is being called after |
105 | * device_del(), which should have done this already via kobject_del(). |
106 | */ |
107 | if (devfreq->dev.kobj.sd) |
108 | sysfs_remove_group(kobj: &devfreq->dev.kobj, grp: &dev_attr_group); |
109 | |
110 | kfree(objp: devfreq->governor_data); |
111 | devfreq->governor_data = NULL; |
112 | } |
113 | |
114 | static int devfreq_userspace_handler(struct devfreq *devfreq, |
115 | unsigned int event, void *data) |
116 | { |
117 | int ret = 0; |
118 | |
119 | switch (event) { |
120 | case DEVFREQ_GOV_START: |
121 | ret = userspace_init(devfreq); |
122 | break; |
123 | case DEVFREQ_GOV_STOP: |
124 | userspace_exit(devfreq); |
125 | break; |
126 | default: |
127 | break; |
128 | } |
129 | |
130 | return ret; |
131 | } |
132 | |
133 | static struct devfreq_governor devfreq_userspace = { |
134 | .name = DEVFREQ_GOV_USERSPACE, |
135 | .get_target_freq = devfreq_userspace_func, |
136 | .event_handler = devfreq_userspace_handler, |
137 | }; |
138 | |
139 | static int __init devfreq_userspace_init(void) |
140 | { |
141 | return devfreq_add_governor(governor: &devfreq_userspace); |
142 | } |
143 | subsys_initcall(devfreq_userspace_init); |
144 | |
145 | static void __exit devfreq_userspace_exit(void) |
146 | { |
147 | int ret; |
148 | |
149 | ret = devfreq_remove_governor(governor: &devfreq_userspace); |
150 | if (ret) |
151 | pr_err("%s: failed remove governor %d\n" , __func__, ret); |
152 | |
153 | return; |
154 | } |
155 | module_exit(devfreq_userspace_exit); |
156 | MODULE_LICENSE("GPL" ); |
157 | |