iio/trigger/iio-trig-hrtimer.c

0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * The industrial I/O periodic hrtimer trigger driver
0004  *
0005  * Copyright (C) Intuitive Aerial AB
0006  * Written by Marten Svanfeldt, marten@intuitiveaerial.com
0007  * Copyright (C) 2012, Analog Devices Inc.
0008  *  Author: Lars-Peter Clausen <lars@metafoo.de>
0009  * Copyright (C) 2015, Intel Corporation
0010  */
0011 #include <linux/kernel.h>
0012 #include <linux/slab.h>
0013 #include <linux/hrtimer.h>
0014
0015 #include <linux/iio/iio.h>
0016 #include <linux/iio/trigger.h>
0017 #include <linux/iio/sw_trigger.h>
0018
0019 /* Defined locally, not in time64.h yet. */
0020 #define PSEC_PER_SEC   1000000000000LL
0021
0022 /* default sampling frequency - 100Hz */
0023 #define HRTIMER_DEFAULT_SAMPLING_FREQUENCY 100
0024
0025 struct iio_hrtimer_info {
0026     struct iio_sw_trigger swt;
0027     struct hrtimer timer;
0028     int sampling_frequency[2];
0029     ktime_t period;
0030 };
0031
0032 static const struct config_item_type iio_hrtimer_type = {
0033     .ct_owner = THIS_MODULE,
0034 };
0035
0036 static
0037 ssize_t iio_hrtimer_show_sampling_frequency(struct device *dev,
0038                         struct device_attribute *attr,
0039                         char *buf)
0040 {
0041     struct iio_trigger *trig = to_iio_trigger(dev);
0042     struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
0043
0044     return iio_format_value(buf, IIO_VAL_INT_PLUS_MICRO,
0045             ARRAY_SIZE(info->sampling_frequency),
0046             info->sampling_frequency);
0047 }
0048
0049 static
0050 ssize_t iio_hrtimer_store_sampling_frequency(struct device *dev,
0051                          struct device_attribute *attr,
0052                          const char *buf, size_t len)
0053 {
0054     struct iio_trigger *trig = to_iio_trigger(dev);
0055     struct iio_hrtimer_info *info = iio_trigger_get_drvdata(trig);
0056     unsigned long long val;
0057     u64 period;
0058     int integer, fract, ret;
0059
0060     ret = iio_str_to_fixpoint(buf, 100, &integer, &fract);
0061     if (ret)
0062         return ret;
0063     if (integer < 0 || fract < 0)
0064         return -ERANGE;
0065
0066     val = fract + 1000ULL * integer;  /* mHz */
0067
0068     if (!val || val > UINT_MAX)
0069         return -EINVAL;
0070
0071     info->sampling_frequency[0] = integer;  /* Hz */
0072     info->sampling_frequency[1] = fract * 1000;  /* uHz */
0073     period = PSEC_PER_SEC;
0074     do_div(period, val);
0075     info->period = period;  /* nS */
0076
0077     return len;
0078 }
0079
0080 static DEVICE_ATTR(sampling_frequency, S_IRUGO | S_IWUSR,
0081            iio_hrtimer_show_sampling_frequency,
0082            iio_hrtimer_store_sampling_frequency);
0083
0084 static struct attribute *iio_hrtimer_attrs[] = {
0085     &dev_attr_sampling_frequency.attr,
0086     NULL
0087 };
0088
0089 static const struct attribute_group iio_hrtimer_attr_group = {
0090     .attrs = iio_hrtimer_attrs,
0091 };
0092
0093 static const struct attribute_group *iio_hrtimer_attr_groups[] = {
0094     &iio_hrtimer_attr_group,
0095     NULL
0096 };
0097
0098 static enum hrtimer_restart iio_hrtimer_trig_handler(struct hrtimer *timer)
0099 {
0100     struct iio_hrtimer_info *info;
0101
0102     info = container_of(timer, struct iio_hrtimer_info, timer);
0103
0104     hrtimer_forward_now(timer, info->period);
0105     iio_trigger_poll(info->swt.trigger);
0106
0107     return HRTIMER_RESTART;
0108 }
0109
0110 static int iio_trig_hrtimer_set_state(struct iio_trigger *trig, bool state)
0111 {
0112     struct iio_hrtimer_info *trig_info;
0113
0114     trig_info = iio_trigger_get_drvdata(trig);
0115
0116     if (state)
0117         hrtimer_start(&trig_info->timer, trig_info->period,
0118                   HRTIMER_MODE_REL_HARD);
0119     else
0120         hrtimer_cancel(&trig_info->timer);
0121
0122     return 0;
0123 }
0124
0125 static const struct iio_trigger_ops iio_hrtimer_trigger_ops = {
0126     .set_trigger_state = iio_trig_hrtimer_set_state,
0127 };
0128
0129 static struct iio_sw_trigger *iio_trig_hrtimer_probe(const char *name)
0130 {
0131     struct iio_hrtimer_info *trig_info;
0132     int ret;
0133
0134     trig_info = kzalloc(sizeof(*trig_info), GFP_KERNEL);
0135     if (!trig_info)
0136         return ERR_PTR(-ENOMEM);
0137
0138     trig_info->swt.trigger = iio_trigger_alloc(NULL, "%s", name);
0139     if (!trig_info->swt.trigger) {
0140         ret = -ENOMEM;
0141         goto err_free_trig_info;
0142     }
0143
0144     iio_trigger_set_drvdata(trig_info->swt.trigger, trig_info);
0145     trig_info->swt.trigger->ops = &iio_hrtimer_trigger_ops;
0146     trig_info->swt.trigger->dev.groups = iio_hrtimer_attr_groups;
0147
0148     hrtimer_init(&trig_info->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
0149     trig_info->timer.function = iio_hrtimer_trig_handler;
0150
0151     trig_info->sampling_frequency[0] = HRTIMER_DEFAULT_SAMPLING_FREQUENCY;
0152     trig_info->period = NSEC_PER_SEC / trig_info->sampling_frequency[0];
0153
0154     ret = iio_trigger_register(trig_info->swt.trigger);
0155     if (ret)
0156         goto err_free_trigger;
0157
0158     iio_swt_group_init_type_name(&trig_info->swt, name, &iio_hrtimer_type);
0159     return &trig_info->swt;
0160 err_free_trigger:
0161     iio_trigger_free(trig_info->swt.trigger);
0162 err_free_trig_info:
0163     kfree(trig_info);
0164
0165     return ERR_PTR(ret);
0166 }
0167
0168 static int iio_trig_hrtimer_remove(struct iio_sw_trigger *swt)
0169 {
0170     struct iio_hrtimer_info *trig_info;
0171
0172     trig_info = iio_trigger_get_drvdata(swt->trigger);
0173
0174     iio_trigger_unregister(swt->trigger);
0175
0176     /* cancel the timer after unreg to make sure no one rearms it */
0177     hrtimer_cancel(&trig_info->timer);
0178     iio_trigger_free(swt->trigger);
0179     kfree(trig_info);
0180
0181     return 0;
0182 }
0183
0184 static const struct iio_sw_trigger_ops iio_trig_hrtimer_ops = {
0185     .probe      = iio_trig_hrtimer_probe,
0186     .remove     = iio_trig_hrtimer_remove,
0187 };
0188
0189 static struct iio_sw_trigger_type iio_trig_hrtimer = {
0190     .name = "hrtimer",
0191     .owner = THIS_MODULE,
0192     .ops = &iio_trig_hrtimer_ops,
0193 };
0194
0195 module_iio_sw_trigger_driver(iio_trig_hrtimer);
0196
0197 MODULE_AUTHOR("Marten Svanfeldt <marten@intuitiveaerial.com>");
0198 MODULE_AUTHOR("Daniel Baluta <daniel.baluta@intel.com>");
0199 MODULE_DESCRIPTION("Periodic hrtimer trigger for the IIO subsystem");
0200 MODULE_LICENSE("GPL v2");