summaryrefslogtreecommitdiff
path: root/lib/linear_ranges.c
blob: d1336c75ccd774370993a9d9c9952378ca0a6259 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
// SPDX-License-Identifier: GPL-2.0
/*
 * helpers to map values in a linear range to range index
 *
 * Original idea borrowed from regulator framework
 *
 * It might be useful if we could support also inversely proportional ranges?
 * Copyright 2020 ROHM Semiconductors
 */

#include <linux/errno.h>
#include <linux/export.h>
#include <linux/kernel.h>
#include <linux/linear_range.h>

/**
 * linear_range_values_in_range - return the amount of values in a range
 * @r:		pointer to linear range where values are counted
 *
 * Compute the amount of values in range pointed by @r. Note, values can
 * be all equal - range with selectors 0,...,2 with step 0 still contains
 * 3 values even though they are all equal.
 *
 * Return: the amount of values in range pointed by @r
 */
unsigned int linear_range_values_in_range(const struct linear_range *r)
{
	if (!r)
		return 0;
	return r->max_sel - r->min_sel + 1;
}
EXPORT_SYMBOL_GPL(linear_range_values_in_range);

/**
 * linear_range_values_in_range_array - return the amount of values in ranges
 * @r:		pointer to array of linear ranges where values are counted
 * @ranges:	amount of ranges we include in computation.
 *
 * Compute the amount of values in ranges pointed by @r. Note, values can
 * be all equal - range with selectors 0,...,2 with step 0 still contains
 * 3 values even though they are all equal.
 *
 * Return: the amount of values in first @ranges ranges pointed by @r
 */
unsigned int linear_range_values_in_range_array(const struct linear_range *r,
						int ranges)
{
	int i, values_in_range = 0;

	for (i = 0; i < ranges; i++) {
		int values;

		values = linear_range_values_in_range(&r[i]);
		if (!values)
			return values;

		values_in_range += values;
	}
	return values_in_range;
}
EXPORT_SYMBOL_GPL(linear_range_values_in_range_array);

/**
 * linear_range_get_max_value - return the largest value in a range
 * @r:		pointer to linear range where value is looked from
 *
 * Return: the largest value in the given range
 */
unsigned int linear_range_get_max_value(const struct linear_range *r)
{
	return r->min + (r->max_sel - r->min_sel) * r->step;
}
EXPORT_SYMBOL_GPL(linear_range_get_max_value);

/**
 * linear_range_get_value - fetch a value from given range
 * @r:		pointer to linear range where value is looked from
 * @selector:	selector for which the value is searched
 * @val:	address where found value is updated
 *
 * Search given ranges for value which matches given selector.
 *
 * Return: 0 on success, -EINVAL given selector is not found from any of the
 * ranges.
 */
int linear_range_get_value(const struct linear_range *r, unsigned int selector,
			   unsigned int *val)
{
	if (r->min_sel > selector || r->max_sel < selector)
		return -EINVAL;

	*val = r->min + (selector - r->min_sel) * r->step;

	return 0;
}
EXPORT_SYMBOL_GPL(linear_range_get_value);

/**
 * linear_range_get_value_array - fetch a value from array of ranges
 * @r:		pointer to array of linear ranges where value is looked from
 * @ranges:	amount of ranges in an array
 * @selector:	selector for which the value is searched
 * @val:	address where found value is updated
 *
 * Search through an array of ranges for value which matches given selector.
 *
 * Return: 0 on success, -EINVAL given selector is not found from any of the
 * ranges.
 */
int linear_range_get_value_array(const struct linear_range *r, int ranges,
				 unsigned int selector, unsigned int *val)
{
	int i;

	for (i = 0; i < ranges; i++)
		if (r[i].min_sel <= selector && r[i].max_sel >= selector)
			return linear_range_get_value(&r[i], selector, val);

	return -EINVAL;
}
EXPORT_SYMBOL_GPL(linear_range_get_value_array);

/**
 * linear_range_get_selector_low - return linear range selector for value
 * @r:		pointer to linear range where selector is looked from
 * @val:	value for which the selector is searched
 * @selector:	address where found selector value is updated
 * @found:	flag to indicate that given value was in the range
 *
 * Return selector which which range value is closest match for given
 * input value. Value is matching if it is equal or smaller than given
 * value. If given value is in the range, then @found is set true.
 *
 * Return: 0 on success, -EINVAL if range is invalid or does not contain
 * value smaller or equal to given value
 */
int linear_range_get_selector_low(const struct linear_range *r,
				  unsigned int val, unsigned int *selector,
				  bool *found)
{
	*found = false;

	if (r->min > val)
		return -EINVAL;

	if (linear_range_get_max_value(r) < val) {
		*selector = r->max_sel;
		return 0;
	}

	*found = true;

	if (r->step == 0)
		*selector = r->min_sel;
	else
		*selector = (val - r->min) / r->step + r->min_sel;

	return 0;
}
EXPORT_SYMBOL_GPL(linear_range_get_selector_low);

/**
 * linear_range_get_selector_low_array - return linear range selector for value
 * @r:		pointer to array of linear ranges where selector is looked from
 * @ranges:	amount of ranges to scan from array
 * @val:	value for which the selector is searched
 * @selector:	address where found selector value is updated
 * @found:	flag to indicate that given value was in the range
 *
 * Scan array of ranges for selector which which range value matches given
 * input value. Value is matching if it is equal or smaller than given
 * value. If given value is found to be in a range scanning is stopped and
 * @found is set true. If a range with values smaller than given value is found
 * but the range max is being smaller than given value, then the ranges
 * biggest selector is updated to @selector but scanning ranges is continued
 * and @found is set to false.
 *
 * Return: 0 on success, -EINVAL if range array is invalid or does not contain
 * range with a value smaller or equal to given value
 */
int linear_range_get_selector_low_array(const struct linear_range *r,
					int ranges, unsigned int val,
					unsigned int *selector, bool *found)
{
	int i;
	int ret = -EINVAL;

	for (i = 0; i < ranges; i++) {
		int tmpret;

		tmpret = linear_range_get_selector_low(&r[i], val, selector,
						       found);
		if (!tmpret)
			ret = 0;

		if (*found)
			break;
	}

	return ret;
}
EXPORT_SYMBOL_GPL(linear_range_get_selector_low_array);

/**
 * linear_range_get_selector_high - return linear range selector for value
 * @r:		pointer to linear range where selector is looked from
 * @val:	value for which the selector is searched
 * @selector:	address where found selector value is updated
 * @found:	flag to indicate that given value was in the range
 *
 * Return selector which which range value is closest match for given
 * input value. Value is matching if it is equal or higher than given
 * value. If given value is in the range, then @found is set true.
 *
 * Return: 0 on success, -EINVAL if range is invalid or does not contain
 * value greater or equal to given value
 */
int linear_range_get_selector_high(const struct linear_range *r,
				   unsigned int val, unsigned int *selector,
				   bool *found)
{
	*found = false;

	if (linear_range_get_max_value(r) < val)
		return -EINVAL;

	if (r->min > val) {
		*selector = r->min_sel;
		return 0;
	}

	*found = true;

	if (r->step == 0)
		*selector = r->max_sel;
	else
		*selector = DIV_ROUND_UP(val - r->min, r->step) + r->min_sel;

	return 0;
}
EXPORT_SYMBOL_GPL(linear_range_get_selector_high);