industrialio-trigger.c

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/* The industrial I/O core, trigger handling functions
 *
 * Copyright (c) 2008 Jonathan Cameron
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */

#include <linux/kernel.h>
#include <linux/idr.h>
#include <linux/err.h>
#include <linux/device.h>
#include <linux/interrupt.h>
#include <linux/list.h>
#include <linux/slab.h>

#include <linux/iio/iio.h>
#include <linux/iio/trigger.h>
#include "iio_core.h"
#include "iio_core_trigger.h"
#include <linux/iio/trigger_consumer.h>

/* RFC - Question of approach
 * Make the common case (single sensor single trigger)
 * simple by starting trigger capture from when first sensors
 * is added.
 *
 * Complex simultaneous start requires use of 'hold' functionality
 * of the trigger. (not implemented)
 *
 * Any other suggestions?
 */

static DEFINE_IDA(iio_trigger_ida);

/* Single list of all available triggers */
static LIST_HEAD(iio_trigger_list);
static DEFINE_MUTEX(iio_trigger_list_lock);

static ssize_t iio_trigger_read_name(struct device *dev,
                     struct device_attribute *attr,
                     char *buf)
{
    struct iio_trigger *trig = to_iio_trigger(dev);
    return sprintf(buf, "%s\n", trig->name);
}

static DEVICE_ATTR(name, S_IRUGO, iio_trigger_read_name, NULL);

static struct attribute *iio_trig_dev_attrs[] = {
    &dev_attr_name.attr,
    NULL,
};

static struct attribute_group iio_trig_attr_group = {
    .attrs  = iio_trig_dev_attrs,
};

static const struct attribute_group *iio_trig_attr_groups[] = {
    &iio_trig_attr_group,
    NULL
};

int iio_trigger_register(struct iio_trigger *trig_info)
{
    int ret;

    trig_info->id = ida_simple_get(&iio_trigger_ida, 0, 0, GFP_KERNEL);
    if (trig_info->id < 0) {
        ret = trig_info->id;
        goto error_ret;
    }
    /* Set the name used for the sysfs directory etc */
    dev_set_name(&trig_info->dev, "trigger%ld",
             (unsigned long) trig_info->id);

    ret = device_add(&trig_info->dev);
    if (ret)
        goto error_unregister_id;

    /* Add to list of available triggers held by the IIO core */
    mutex_lock(&iio_trigger_list_lock);
    list_add_tail(&trig_info->list, &iio_trigger_list);
    mutex_unlock(&iio_trigger_list_lock);

    return 0;

error_unregister_id:
    ida_simple_remove(&iio_trigger_ida, trig_info->id);
error_ret:
    return ret;
}
EXPORT_SYMBOL(iio_trigger_register);

void iio_trigger_unregister(struct iio_trigger *trig_info)
{
    mutex_lock(&iio_trigger_list_lock);
    list_del(&trig_info->list);
    mutex_unlock(&iio_trigger_list_lock);

    ida_simple_remove(&iio_trigger_ida, trig_info->id);
    /* Possible issue in here */
    device_unregister(&trig_info->dev);
}
EXPORT_SYMBOL(iio_trigger_unregister);

static struct iio_trigger *iio_trigger_find_by_name(const char *name,
                            size_t len)
{
    struct iio_trigger *trig = NULL, *iter;

    mutex_lock(&iio_trigger_list_lock);
    list_for_each_entry(iter, &iio_trigger_list, list)
        if (sysfs_streq(iter->name, name)) {
            trig = iter;
            break;
        }
    mutex_unlock(&iio_trigger_list_lock);

    return trig;
}

void iio_trigger_poll(struct iio_trigger *trig, s64 time)
{
    int i;
    if (!trig->use_count)
        for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++)
            if (trig->subirqs[i].enabled) {
                trig->use_count++;
                generic_handle_irq(trig->subirq_base + i);
            }
}
EXPORT_SYMBOL(iio_trigger_poll);

irqreturn_t iio_trigger_generic_data_rdy_poll(int irq, void *private)
{
    iio_trigger_poll(private, iio_get_time_ns());
    return IRQ_HANDLED;
}
EXPORT_SYMBOL(iio_trigger_generic_data_rdy_poll);

void iio_trigger_poll_chained(struct iio_trigger *trig, s64 time)
{
    int i;
    if (!trig->use_count)
        for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++)
            if (trig->subirqs[i].enabled) {
                trig->use_count++;
                handle_nested_irq(trig->subirq_base + i);
            }
}
EXPORT_SYMBOL(iio_trigger_poll_chained);

void iio_trigger_notify_done(struct iio_trigger *trig)
{
    trig->use_count--;
    if (trig->use_count == 0 && trig->ops && trig->ops->try_reenable)
        if (trig->ops->try_reenable(trig))
            /* Missed and interrupt so launch new poll now */
            iio_trigger_poll(trig, 0);
}
EXPORT_SYMBOL(iio_trigger_notify_done);

/* Trigger Consumer related functions */
static int iio_trigger_get_irq(struct iio_trigger *trig)
{
    int ret;
    mutex_lock(&trig->pool_lock);
    ret = bitmap_find_free_region(trig->pool,
                      CONFIG_IIO_CONSUMERS_PER_TRIGGER,
                      ilog2(1));
    mutex_unlock(&trig->pool_lock);
    if (ret >= 0)
        ret += trig->subirq_base;

    return ret;
}

static void iio_trigger_put_irq(struct iio_trigger *trig, int irq)
{
    mutex_lock(&trig->pool_lock);
    clear_bit(irq - trig->subirq_base, trig->pool);
    mutex_unlock(&trig->pool_lock);
}

/* Complexity in here.  With certain triggers (datardy) an acknowledgement
 * may be needed if the pollfuncs do not include the data read for the
 * triggering device.
 * This is not currently handled.  Alternative of not enabling trigger unless
 * the relevant function is in there may be the best option.
 */
/* Worth protecting against double additions?*/
static int iio_trigger_attach_poll_func(struct iio_trigger *trig,
                    struct iio_poll_func *pf)
{
    int ret = 0;
    bool notinuse
        = bitmap_empty(trig->pool, CONFIG_IIO_CONSUMERS_PER_TRIGGER);

    /* Prevent the module being removed whilst attached to a trigger */
    __module_get(pf->indio_dev->info->driver_module);
    pf->irq = iio_trigger_get_irq(trig);
    ret = request_threaded_irq(pf->irq, pf->h, pf->thread,
                   pf->type, pf->name,
                   pf);
    if (ret < 0) {
        module_put(pf->indio_dev->info->driver_module);
        return ret;
    }

    if (trig->ops && trig->ops->set_trigger_state && notinuse) {
        ret = trig->ops->set_trigger_state(trig, true);
        if (ret < 0)
            module_put(pf->indio_dev->info->driver_module);
    }

    return ret;
}

static int iio_trigger_detach_poll_func(struct iio_trigger *trig,
                     struct iio_poll_func *pf)
{
    int ret = 0;
    bool no_other_users
        = (bitmap_weight(trig->pool,
                 CONFIG_IIO_CONSUMERS_PER_TRIGGER)
           == 1);
    if (trig->ops && trig->ops->set_trigger_state && no_other_users) {
        ret = trig->ops->set_trigger_state(trig, false);
        if (ret)
            goto error_ret;
    }
    iio_trigger_put_irq(trig, pf->irq);
    free_irq(pf->irq, pf);
    module_put(pf->indio_dev->info->driver_module);

error_ret:
    return ret;
}

irqreturn_t iio_pollfunc_store_time(int irq, void *p)
{
    struct iio_poll_func *pf = p;
    pf->timestamp = iio_get_time_ns();
    return IRQ_WAKE_THREAD;
}
EXPORT_SYMBOL(iio_pollfunc_store_time);

struct iio_poll_func
*iio_alloc_pollfunc(irqreturn_t (*h)(int irq, void *p),
            irqreturn_t (*thread)(int irq, void *p),
            int type,
            struct iio_dev *indio_dev,
            const char *fmt,
            ...)
{
    va_list vargs;
    struct iio_poll_func *pf;

    pf = kmalloc(sizeof *pf, GFP_KERNEL);
    if (pf == NULL)
        return NULL;
    va_start(vargs, fmt);
    pf->name = kvasprintf(GFP_KERNEL, fmt, vargs);
    va_end(vargs);
    if (pf->name == NULL) {
        kfree(pf);
        return NULL;
    }
    pf->h = h;
    pf->thread = thread;
    pf->type = type;
    pf->indio_dev = indio_dev;

    return pf;
}
EXPORT_SYMBOL_GPL(iio_alloc_pollfunc);

void iio_dealloc_pollfunc(struct iio_poll_func *pf)
{
    kfree(pf->name);
    kfree(pf);
}
EXPORT_SYMBOL_GPL(iio_dealloc_pollfunc);

static ssize_t iio_trigger_read_current(struct device *dev,
                    struct device_attribute *attr,
                    char *buf)
{
    struct iio_dev *indio_dev = dev_to_iio_dev(dev);

    if (indio_dev->trig)
        return sprintf(buf, "%s\n", indio_dev->trig->name);
    return 0;
}

static ssize_t iio_trigger_write_current(struct device *dev,
                     struct device_attribute *attr,
                     const char *buf,
                     size_t len)
{
    struct iio_dev *indio_dev = dev_to_iio_dev(dev);
    struct iio_trigger *oldtrig = indio_dev->trig;
    struct iio_trigger *trig;
    int ret;

    mutex_lock(&indio_dev->mlock);
    if (indio_dev->currentmode == INDIO_BUFFER_TRIGGERED) {
        mutex_unlock(&indio_dev->mlock);
        return -EBUSY;
    }
    mutex_unlock(&indio_dev->mlock);

    trig = iio_trigger_find_by_name(buf, len);
    if (oldtrig == trig)
        return len;

    if (trig && indio_dev->info->validate_trigger) {
        ret = indio_dev->info->validate_trigger(indio_dev, trig);
        if (ret)
            return ret;
    }

    if (trig && trig->ops && trig->ops->validate_device) {
        ret = trig->ops->validate_device(trig, indio_dev);
        if (ret)
            return ret;
    }

    indio_dev->trig = trig;

    if (oldtrig && indio_dev->trig != oldtrig)
        iio_trigger_put(oldtrig);
    if (indio_dev->trig)
        iio_trigger_get(indio_dev->trig);

    return len;
}

static DEVICE_ATTR(current_trigger, S_IRUGO | S_IWUSR,
           iio_trigger_read_current,
           iio_trigger_write_current);

static struct attribute *iio_trigger_consumer_attrs[] = {
    &dev_attr_current_trigger.attr,
    NULL,
};

static const struct attribute_group iio_trigger_consumer_attr_group = {
    .name = "trigger",
    .attrs = iio_trigger_consumer_attrs,
};

static void iio_trig_release(struct device *device)
{
    struct iio_trigger *trig = to_iio_trigger(device);
    int i;

    if (trig->subirq_base) {
        for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
            irq_modify_status(trig->subirq_base + i,
                      IRQ_NOAUTOEN,
                      IRQ_NOREQUEST | IRQ_NOPROBE);
            irq_set_chip(trig->subirq_base + i,
                     NULL);
            irq_set_handler(trig->subirq_base + i,
                    NULL);
        }

        irq_free_descs(trig->subirq_base,
                   CONFIG_IIO_CONSUMERS_PER_TRIGGER);
    }
    kfree(trig->name);
    kfree(trig);
}

static struct device_type iio_trig_type = {
    .release = iio_trig_release,
    .groups = iio_trig_attr_groups,
};

static void iio_trig_subirqmask(struct irq_data *d)
{
    struct irq_chip *chip = irq_data_get_irq_chip(d);
    struct iio_trigger *trig
        = container_of(chip,
                   struct iio_trigger, subirq_chip);
    trig->subirqs[d->irq - trig->subirq_base].enabled = false;
}

static void iio_trig_subirqunmask(struct irq_data *d)
{
    struct irq_chip *chip = irq_data_get_irq_chip(d);
    struct iio_trigger *trig
        = container_of(chip,
                   struct iio_trigger, subirq_chip);
    trig->subirqs[d->irq - trig->subirq_base].enabled = true;
}

struct iio_trigger *iio_trigger_alloc(const char *fmt, ...)
{
    va_list vargs;
    struct iio_trigger *trig;
    trig = kzalloc(sizeof *trig, GFP_KERNEL);
    if (trig) {
        int i;
        trig->dev.type = &iio_trig_type;
        trig->dev.bus = &iio_bus_type;
        device_initialize(&trig->dev);

        mutex_init(&trig->pool_lock);
        trig->subirq_base
            = irq_alloc_descs(-1, 0,
                      CONFIG_IIO_CONSUMERS_PER_TRIGGER,
                      0);
        if (trig->subirq_base < 0) {
            kfree(trig);
            return NULL;
        }
        va_start(vargs, fmt);
        trig->name = kvasprintf(GFP_KERNEL, fmt, vargs);
        va_end(vargs);
        if (trig->name == NULL) {
            irq_free_descs(trig->subirq_base,
                       CONFIG_IIO_CONSUMERS_PER_TRIGGER);
            kfree(trig);
            return NULL;
        }
        trig->subirq_chip.name = trig->name;
        trig->subirq_chip.irq_mask = &iio_trig_subirqmask;
        trig->subirq_chip.irq_unmask = &iio_trig_subirqunmask;
        for (i = 0; i < CONFIG_IIO_CONSUMERS_PER_TRIGGER; i++) {
            irq_set_chip(trig->subirq_base + i,
                     &trig->subirq_chip);
            irq_set_handler(trig->subirq_base + i,
                    &handle_simple_irq);
            irq_modify_status(trig->subirq_base + i,
                      IRQ_NOREQUEST | IRQ_NOAUTOEN,
                      IRQ_NOPROBE);
        }
        get_device(&trig->dev);
    }
    return trig;
}
EXPORT_SYMBOL(iio_trigger_alloc);

void iio_trigger_free(struct iio_trigger *trig)
{
    if (trig)
        put_device(&trig->dev);
}
EXPORT_SYMBOL(iio_trigger_free);

void iio_device_register_trigger_consumer(struct iio_dev *indio_dev)
{
    indio_dev->groups[indio_dev->groupcounter++] =
        &iio_trigger_consumer_attr_group;
}

void iio_device_unregister_trigger_consumer(struct iio_dev *indio_dev)
{
    /* Clean up and associated but not attached triggers references */
    if (indio_dev->trig)
        iio_trigger_put(indio_dev->trig);
}

int iio_triggered_buffer_postenable(struct iio_dev *indio_dev)
{
    return iio_trigger_attach_poll_func(indio_dev->trig,
                        indio_dev->pollfunc);
}
EXPORT_SYMBOL(iio_triggered_buffer_postenable);

int iio_triggered_buffer_predisable(struct iio_dev *indio_dev)
{
    return iio_trigger_detach_poll_func(indio_dev->trig,
                         indio_dev->pollfunc);
}
EXPORT_SYMBOL(iio_triggered_buffer_predisable);