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linux/drivers/iio/industrialio-event.c
Lars-Peter Clausen 1b9dc91e41 iio: events: Make iio_push_event() IRQ context save 
Currently it is not save to call iio_push_event() from hard IRQ context since
the IIO event code uses spin_lock()/spin_unlock() and it is not save to mix
calls to spin_lock()/spin_unlock() from different contexts on the same lock.
E.g. if the lock is being held in iio_event_chrdev_read() and an interrupts
kicks in and the interrupt handler calls iio_push_event() we end uo with a
deadlock.

This patch updates iio_push_event() to use spin_lock_irqsave()/
spin_unlock_irqstrestore(), since it can be called from both IRQ and non-IRQ
context. All other other users of the lock, which are always run in non-IRQ
context, are updated to spin_lock_irq()/spin_unlock_irq().

Signed-off-by: Lars-Peter Clausen <lars@metafoo.de>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>
2013-03-17 20:04:45 +00:00

451 lines
11 KiB
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/* Industrial I/O event handling
*
* 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.
*
* Based on elements of hwmon and input subsystems.
*/
#include <linux/anon_inodes.h>
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/kfifo.h>
#include <linux/module.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/wait.h>
#include <linux/iio/iio.h>
#include "iio_core.h"
#include <linux/iio/sysfs.h>
#include <linux/iio/events.h>
/**
* struct iio_event_interface - chrdev interface for an event line
* @wait: wait queue to allow blocking reads of events
* @det_events: list of detected events
* @dev_attr_list: list of event interface sysfs attribute
* @flags: file operations related flags including busy flag.
* @group: event interface sysfs attribute group
*/
struct iio_event_interface {
wait_queue_head_t wait;
DECLARE_KFIFO(det_events, struct iio_event_data, 16);
struct list_head dev_attr_list;
unsigned long flags;
struct attribute_group group;
};
int iio_push_event(struct iio_dev *indio_dev, u64 ev_code, s64 timestamp)
{
struct iio_event_interface *ev_int = indio_dev->event_interface;
struct iio_event_data ev;
unsigned long flags;
int copied;
/* Does anyone care? */
spin_lock_irqsave(&ev_int->wait.lock, flags);
if (test_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
ev.id = ev_code;
ev.timestamp = timestamp;
copied = kfifo_put(&ev_int->det_events, &ev);
if (copied != 0)
wake_up_locked_poll(&ev_int->wait, POLLIN);
}
spin_unlock_irqrestore(&ev_int->wait.lock, flags);
return 0;
}
EXPORT_SYMBOL(iio_push_event);
/**
* iio_event_poll() - poll the event queue to find out if it has data
*/
static unsigned int iio_event_poll(struct file *filep,
struct poll_table_struct *wait)
{
struct iio_event_interface *ev_int = filep->private_data;
unsigned int events = 0;
poll_wait(filep, &ev_int->wait, wait);
spin_lock_irq(&ev_int->wait.lock);
if (!kfifo_is_empty(&ev_int->det_events))
events = POLLIN | POLLRDNORM;
spin_unlock_irq(&ev_int->wait.lock);
return events;
}
static ssize_t iio_event_chrdev_read(struct file *filep,
char __user *buf,
size_t count,
loff_t *f_ps)
{
struct iio_event_interface *ev_int = filep->private_data;
unsigned int copied;
int ret;
if (count < sizeof(struct iio_event_data))
return -EINVAL;
spin_lock_irq(&ev_int->wait.lock);
if (kfifo_is_empty(&ev_int->det_events)) {
if (filep->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
goto error_unlock;
}
/* Blocking on device; waiting for something to be there */
ret = wait_event_interruptible_locked_irq(ev_int->wait,
!kfifo_is_empty(&ev_int->det_events));
if (ret)
goto error_unlock;
/* Single access device so no one else can get the data */
}
ret = kfifo_to_user(&ev_int->det_events, buf, count, &copied);
error_unlock:
spin_unlock_irq(&ev_int->wait.lock);
return ret ? ret : copied;
}
static int iio_event_chrdev_release(struct inode *inode, struct file *filep)
{
struct iio_event_interface *ev_int = filep->private_data;
spin_lock_irq(&ev_int->wait.lock);
__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
/*
* In order to maintain a clean state for reopening,
* clear out any awaiting events. The mask will prevent
* any new __iio_push_event calls running.
*/
kfifo_reset_out(&ev_int->det_events);
spin_unlock_irq(&ev_int->wait.lock);
return 0;
}
static const struct file_operations iio_event_chrdev_fileops = {
.read = iio_event_chrdev_read,
.poll = iio_event_poll,
.release = iio_event_chrdev_release,
.owner = THIS_MODULE,
.llseek = noop_llseek,
};
int iio_event_getfd(struct iio_dev *indio_dev)
{
struct iio_event_interface *ev_int = indio_dev->event_interface;
int fd;
if (ev_int == NULL)
return -ENODEV;
spin_lock_irq(&ev_int->wait.lock);
if (__test_and_set_bit(IIO_BUSY_BIT_POS, &ev_int->flags)) {
spin_unlock_irq(&ev_int->wait.lock);
return -EBUSY;
}
spin_unlock_irq(&ev_int->wait.lock);
fd = anon_inode_getfd("iio:event",
&iio_event_chrdev_fileops, ev_int, O_RDONLY);
if (fd < 0) {
spin_lock_irq(&ev_int->wait.lock);
__clear_bit(IIO_BUSY_BIT_POS, &ev_int->flags);
spin_unlock_irq(&ev_int->wait.lock);
}
return fd;
}
static const char * const iio_ev_type_text[] = {
[IIO_EV_TYPE_THRESH] = "thresh",
[IIO_EV_TYPE_MAG] = "mag",
[IIO_EV_TYPE_ROC] = "roc",
[IIO_EV_TYPE_THRESH_ADAPTIVE] = "thresh_adaptive",
[IIO_EV_TYPE_MAG_ADAPTIVE] = "mag_adaptive",
};
static const char * const iio_ev_dir_text[] = {
[IIO_EV_DIR_EITHER] = "either",
[IIO_EV_DIR_RISING] = "rising",
[IIO_EV_DIR_FALLING] = "falling"
};
static ssize_t iio_ev_state_store(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_dev_attr *this_attr = to_iio_dev_attr(attr);
int ret;
bool val;
ret = strtobool(buf, &val);
if (ret < 0)
return ret;
ret = indio_dev->info->write_event_config(indio_dev,
this_attr->address,
val);
return (ret < 0) ? ret : len;
}
static ssize_t iio_ev_state_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
int val = indio_dev->info->read_event_config(indio_dev,
this_attr->address);
if (val < 0)
return val;
else
return sprintf(buf, "%d\n", val);
}
static ssize_t iio_ev_value_show(struct device *dev,
struct device_attribute *attr,
char *buf)
{
struct iio_dev *indio_dev = dev_to_iio_dev(dev);
struct iio_dev_attr *this_attr = to_iio_dev_attr(attr);
int val, ret;
ret = indio_dev->info->read_event_value(indio_dev,
this_attr->address, &val);
if (ret < 0)
return ret;
return sprintf(buf, "%d\n", val);
}
static ssize_t iio_ev_value_store(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_dev_attr *this_attr = to_iio_dev_attr(attr);
int val;
int ret;
if (!indio_dev->info->write_event_value)
return -EINVAL;
ret = kstrtoint(buf, 10, &val);
if (ret)
return ret;
ret = indio_dev->info->write_event_value(indio_dev, this_attr->address,
val);
if (ret < 0)
return ret;
return len;
}
static int iio_device_add_event_sysfs(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan)
{
int ret = 0, i, attrcount = 0;
u64 mask = 0;
char *postfix;
if (!chan->event_mask)
return 0;
for_each_set_bit(i, &chan->event_mask, sizeof(chan->event_mask)*8) {
postfix = kasprintf(GFP_KERNEL, "%s_%s_en",
iio_ev_type_text[i/IIO_EV_DIR_MAX],
iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
if (postfix == NULL) {
ret = -ENOMEM;
goto error_ret;
}
if (chan->modified)
mask = IIO_MOD_EVENT_CODE(chan->type, 0, chan->channel,
i/IIO_EV_DIR_MAX,
i%IIO_EV_DIR_MAX);
else if (chan->differential)
mask = IIO_EVENT_CODE(chan->type,
0, 0,
i%IIO_EV_DIR_MAX,
i/IIO_EV_DIR_MAX,
0,
chan->channel,
chan->channel2);
else
mask = IIO_UNMOD_EVENT_CODE(chan->type,
chan->channel,
i/IIO_EV_DIR_MAX,
i%IIO_EV_DIR_MAX);
ret = __iio_add_chan_devattr(postfix,
chan,
&iio_ev_state_show,
iio_ev_state_store,
mask,
0,
&indio_dev->dev,
&indio_dev->event_interface->
dev_attr_list);
kfree(postfix);
if (ret)
goto error_ret;
attrcount++;
postfix = kasprintf(GFP_KERNEL, "%s_%s_value",
iio_ev_type_text[i/IIO_EV_DIR_MAX],
iio_ev_dir_text[i%IIO_EV_DIR_MAX]);
if (postfix == NULL) {
ret = -ENOMEM;
goto error_ret;
}
ret = __iio_add_chan_devattr(postfix, chan,
iio_ev_value_show,
iio_ev_value_store,
mask,
0,
&indio_dev->dev,
&indio_dev->event_interface->
dev_attr_list);
kfree(postfix);
if (ret)
goto error_ret;
attrcount++;
}
ret = attrcount;
error_ret:
return ret;
}
static inline void __iio_remove_event_config_attrs(struct iio_dev *indio_dev)
{
struct iio_dev_attr *p, *n;
list_for_each_entry_safe(p, n,
&indio_dev->event_interface->
dev_attr_list, l) {
kfree(p->dev_attr.attr.name);
kfree(p);
}
}
static inline int __iio_add_event_config_attrs(struct iio_dev *indio_dev)
{
int j, ret, attrcount = 0;
/* Dynically created from the channels array */
for (j = 0; j < indio_dev->num_channels; j++) {
ret = iio_device_add_event_sysfs(indio_dev,
&indio_dev->channels[j]);
if (ret < 0)
return ret;
attrcount += ret;
}
return attrcount;
}
static bool iio_check_for_dynamic_events(struct iio_dev *indio_dev)
{
int j;
for (j = 0; j < indio_dev->num_channels; j++)
if (indio_dev->channels[j].event_mask != 0)
return true;
return false;
}
static void iio_setup_ev_int(struct iio_event_interface *ev_int)
{
INIT_KFIFO(ev_int->det_events);
init_waitqueue_head(&ev_int->wait);
}
static const char *iio_event_group_name = "events";
int iio_device_register_eventset(struct iio_dev *indio_dev)
{
struct iio_dev_attr *p;
int ret = 0, attrcount_orig = 0, attrcount, attrn;
struct attribute **attr;
if (!(indio_dev->info->event_attrs ||
iio_check_for_dynamic_events(indio_dev)))
return 0;
indio_dev->event_interface =
kzalloc(sizeof(struct iio_event_interface), GFP_KERNEL);
if (indio_dev->event_interface == NULL) {
ret = -ENOMEM;
goto error_ret;
}
INIT_LIST_HEAD(&indio_dev->event_interface->dev_attr_list);
iio_setup_ev_int(indio_dev->event_interface);
if (indio_dev->info->event_attrs != NULL) {
attr = indio_dev->info->event_attrs->attrs;
while (*attr++ != NULL)
attrcount_orig++;
}
attrcount = attrcount_orig;
if (indio_dev->channels) {
ret = __iio_add_event_config_attrs(indio_dev);
if (ret < 0)
goto error_free_setup_event_lines;
attrcount += ret;
}
indio_dev->event_interface->group.name = iio_event_group_name;
indio_dev->event_interface->group.attrs = kcalloc(attrcount + 1,
sizeof(indio_dev->event_interface->group.attrs[0]),
GFP_KERNEL);
if (indio_dev->event_interface->group.attrs == NULL) {
ret = -ENOMEM;
goto error_free_setup_event_lines;
}
if (indio_dev->info->event_attrs)
memcpy(indio_dev->event_interface->group.attrs,
indio_dev->info->event_attrs->attrs,
sizeof(indio_dev->event_interface->group.attrs[0])
*attrcount_orig);
attrn = attrcount_orig;
/* Add all elements from the list. */
list_for_each_entry(p,
&indio_dev->event_interface->dev_attr_list,
l)
indio_dev->event_interface->group.attrs[attrn++] =
&p->dev_attr.attr;
indio_dev->groups[indio_dev->groupcounter++] =
&indio_dev->event_interface->group;
return 0;
error_free_setup_event_lines:
__iio_remove_event_config_attrs(indio_dev);
kfree(indio_dev->event_interface);
error_ret:
return ret;
}
void iio_device_unregister_eventset(struct iio_dev *indio_dev)
{
if (indio_dev->event_interface == NULL)
return;
__iio_remove_event_config_attrs(indio_dev);
kfree(indio_dev->event_interface->group.attrs);
kfree(indio_dev->event_interface);
}
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