diff options
| -rw-r--r-- | include/linux/linear_range.h | 48 | ||||
| -rw-r--r-- | lib/Kconfig | 3 | ||||
| -rw-r--r-- | lib/Makefile | 1 | ||||
| -rw-r--r-- | lib/linear_ranges.c | 241 |
4 files changed, 293 insertions, 0 deletions
diff --git a/include/linux/linear_range.h b/include/linux/linear_range.h new file mode 100644 index 000000000000..17b5943727d5 --- /dev/null +++ b/include/linux/linear_range.h @@ -0,0 +1,48 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* Copyright (C) 2020 ROHM Semiconductors */ + +#ifndef LINEAR_RANGE_H +#define LINEAR_RANGE_H + +#include <linux/types.h> + +/** + * struct linear_range - table of selector - value pairs + * + * Define a lookup-table for range of values. Intended to help when looking + * for a register value matching certaing physical measure (like voltage). + * Usable when increment of one in register always results a constant increment + * of the physical measure (like voltage). + * + * @min: Lowest value in range + * @min_sel: Lowest selector for range + * @max_sel: Highest selector for range + * @step: Value step size + */ +struct linear_range { + unsigned int min; + unsigned int min_sel; + unsigned int max_sel; + unsigned int step; +}; + +unsigned int linear_range_values_in_range(const struct linear_range *r); +unsigned int linear_range_values_in_range_array(const struct linear_range *r, + int ranges); +unsigned int linear_range_get_max_value(const struct linear_range *r); + +int linear_range_get_value(const struct linear_range *r, unsigned int selector, + unsigned int *val); +int linear_range_get_value_array(const struct linear_range *r, int ranges, + unsigned int selector, unsigned int *val); +int linear_range_get_selector_low(const struct linear_range *r, + unsigned int val, unsigned int *selector, + bool *found); +int linear_range_get_selector_high(const struct linear_range *r, + unsigned int val, unsigned int *selector, + bool *found); +int linear_range_get_selector_low_array(const struct linear_range *r, + int ranges, unsigned int val, + unsigned int *selector, bool *found); + +#endif diff --git a/lib/Kconfig b/lib/Kconfig index 5d53f9609c25..8ec05335426c 100644 --- a/lib/Kconfig +++ b/lib/Kconfig @@ -19,6 +19,9 @@ config RAID6_PQ_BENCHMARK Benchmark all available RAID6 PQ functions on init and choose the fastest one. +config LINEAR_RANGES + tristate + config PACKING bool "Generic bitfield packing and unpacking" default n diff --git a/lib/Makefile b/lib/Makefile index 685aee60de1d..20b9cfdcad69 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -125,6 +125,7 @@ obj-$(CONFIG_DEBUG_LIST) += list_debug.o obj-$(CONFIG_DEBUG_OBJECTS) += debugobjects.o obj-$(CONFIG_BITREVERSE) += bitrev.o +obj-$(CONFIG_LINEAR_RANGES) += linear_ranges.o obj-$(CONFIG_PACKING) += packing.o obj-$(CONFIG_CRC_CCITT) += crc-ccitt.o obj-$(CONFIG_CRC16) += crc16.o diff --git a/lib/linear_ranges.c b/lib/linear_ranges.c new file mode 100644 index 000000000000..d1336c75ccd7 --- /dev/null +++ b/lib/linear_ranges.c @@ -0,0 +1,241 @@ +// 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); |