Kyle Swenson | cc33c24 | 2022-05-16 10:38:04 -0600 | [diff] [blame] | 1 | /* |
| 2 | * ./kernel_modules/qcom-adc/adc-averaging.c |
| 3 | * |
| 4 | * This file does some basic FIR averaging on a fifo; it is intended to be used |
| 5 | * with the ADS7924 device driver |
| 6 | * |
| 7 | * Author: Cradlepoint Technology, Inc. <source@cradlepoint.com> |
| 8 | * Kyle Swenson <kswenson@cradlepoint.com> |
| 9 | * |
| 10 | * Copyright 2017 Cradlepoint Technology, Inc. |
| 11 | * |
| 12 | * This program is free software; you can redistribute it and/or modify it |
| 13 | * under the terms of the GNU General Public License version 2 as published by |
| 14 | * the Free Software Foundation. |
| 15 | * |
| 16 | * This program is distributed in the hope that it will be useful, but WITHOUT |
| 17 | * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or |
| 18 | * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for |
| 19 | * more details. |
| 20 | * |
| 21 | */ |
Kyle Swenson | 89648b2 | 2022-05-16 10:56:50 -0600 | [diff] [blame] | 22 | #include <linux/device.h> |
Kyle Swenson | cc33c24 | 2022-05-16 10:38:04 -0600 | [diff] [blame] | 23 | #include <linux/kernel.h> |
| 24 | #include <linux/module.h> |
| 25 | #include <linux/err.h> |
| 26 | #include <linux/slab.h> |
| 27 | #include "adc-averaging.h" |
| 28 | |
| 29 | |
| 30 | void free_adc_channel(struct adc_channel *ch) |
| 31 | { |
Kyle Swenson | 89648b2 | 2022-05-16 10:56:50 -0600 | [diff] [blame] | 32 | mutex_lock(&ch->lock); |
Kyle Swenson | cc33c24 | 2022-05-16 10:38:04 -0600 | [diff] [blame] | 33 | if (ch->samples) { |
Kyle Swenson | 89648b2 | 2022-05-16 10:56:50 -0600 | [diff] [blame] | 34 | devm_kfree(ch->parent, ch->samples); |
| 35 | ch->samples = NULL; |
Kyle Swenson | cc33c24 | 2022-05-16 10:38:04 -0600 | [diff] [blame] | 36 | } |
Kyle Swenson | 89648b2 | 2022-05-16 10:56:50 -0600 | [diff] [blame] | 37 | mutex_unlock(&ch->lock); |
| 38 | mutex_destroy(&ch->lock); |
| 39 | devm_kfree(ch->parent, ch); |
Kyle Swenson | cc33c24 | 2022-05-16 10:38:04 -0600 | [diff] [blame] | 40 | } |
| 41 | |
Kyle Swenson | 89648b2 | 2022-05-16 10:56:50 -0600 | [diff] [blame] | 42 | struct adc_channel *create_adc_channel(struct device * dev, uint16_t fifo_length) |
Kyle Swenson | cc33c24 | 2022-05-16 10:38:04 -0600 | [diff] [blame] | 43 | { |
| 44 | struct adc_channel *ch; |
| 45 | if (fifo_length >= MAX_SAMPLE_LENGTH) { |
| 46 | printk(KERN_ALERT "Requested a ADC buffer length (%u) exceedes max (%u)\n", fifo_length, MAX_SAMPLE_LENGTH); |
| 47 | return NULL; |
| 48 | |
| 49 | } |
Kyle Swenson | 89648b2 | 2022-05-16 10:56:50 -0600 | [diff] [blame] | 50 | ch = devm_kzalloc(dev, sizeof(struct adc_channel), GFP_KERNEL); |
| 51 | if (!ch) |
Kyle Swenson | cc33c24 | 2022-05-16 10:38:04 -0600 | [diff] [blame] | 52 | return NULL; |
Kyle Swenson | 89648b2 | 2022-05-16 10:56:50 -0600 | [diff] [blame] | 53 | |
| 54 | ch->samples = devm_kzalloc(dev, sizeof(uint16_t) * fifo_length, GFP_KERNEL); |
| 55 | if (!ch->samples) |
Kyle Swenson | cc33c24 | 2022-05-16 10:38:04 -0600 | [diff] [blame] | 56 | return NULL; |
Kyle Swenson | 89648b2 | 2022-05-16 10:56:50 -0600 | [diff] [blame] | 57 | |
Kyle Swenson | cc33c24 | 2022-05-16 10:38:04 -0600 | [diff] [blame] | 58 | ch->total_length = fifo_length; |
| 59 | ch->index = 0; |
| 60 | mutex_init(&ch->lock); |
Kyle Swenson | 89648b2 | 2022-05-16 10:56:50 -0600 | [diff] [blame] | 61 | ch->parent = dev; |
Kyle Swenson | cc33c24 | 2022-05-16 10:38:04 -0600 | [diff] [blame] | 62 | return ch; |
| 63 | } |
| 64 | |
| 65 | uint16_t compute_average(struct adc_channel *ch) |
| 66 | { |
| 67 | uint32_t sum=0; |
| 68 | uint16_t average; |
| 69 | int i = 0; |
| 70 | mutex_lock(&ch->lock); |
| 71 | for (i = 0; i < ch->total_length; i++) { |
| 72 | sum += ch->samples[i]; |
| 73 | } |
| 74 | average = DIV_ROUND_CLOSEST(sum, ch->total_length); |
| 75 | mutex_unlock(&ch->lock); |
| 76 | return average; |
| 77 | } |
| 78 | |
| 79 | void add_sample(struct adc_channel *ch, uint16_t sample) |
| 80 | { |
| 81 | mutex_lock(&ch->lock); |
| 82 | ch->samples[ch->index++] = sample; |
| 83 | if (ch->index >= ch->total_length) |
| 84 | ch->index = 0; |
| 85 | mutex_unlock(&ch->lock); |
| 86 | } |