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With this change, an ioctl() call is added to open a character device for a
buffer. The ioctl() number is 'i' 0x91, which follows the
IIO_GET_EVENT_FD_IOCTL ioctl.
The ioctl() will return an FD for the requested buffer index. The indexes
are the same from the /sys/iio/devices/iio:deviceX/bufferY (i.e. the Y
variable).
Since there doesn't seem to be a sane way to return the FD for buffer0 to
be the same FD for the /dev/iio:deviceX, this ioctl() will return another
FD for buffer0 (or the first buffer). This duplicate FD will be able to
access the same buffer object (for buffer0) as accessing directly the
/dev/iio:deviceX chardev.
Also, there is no IIO_BUFFER_GET_BUFFER_COUNT ioctl() implemented, as the
index for each buffer (and the count) can be deduced from the
'/sys/bus/iio/devices/iio:deviceX/bufferY' folders (i.e the number of
bufferY folders).
Used following C code to test this:
-------------------------------------------------------------------
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <fcntl.h"
#include <errno.h>
#define IIO_BUFFER_GET_FD_IOCTL _IOWR('i', 0x91, int)
int main(int argc, char *argv[])
{
int fd;
int fd1;
int ret;
if ((fd = open("/dev/iio:device0", O_RDWR))<0) {
fprintf(stderr, "Error open() %d errno %d\n",fd, errno);
return -1;
}
fprintf(stderr, "Using FD %d\n", fd);
fd1 = atoi(argv[1]);
ret = ioctl(fd, IIO_BUFFER_GET_FD_IOCTL, &fd1);
if (ret < 0) {
fprintf(stderr, "Error for buffer %d ioctl() %d errno %d\n", fd1, ret, errno);
close(fd);
return -1;
}
fprintf(stderr, "Got FD %d\n", fd1);
close(fd1);
close(fd);
return 0;
}
-------------------------------------------------------------------
Results are:
-------------------------------------------------------------------
# ./test 0
Using FD 3
Got FD 4
# ./test 1
Using FD 3
Got FD 4
# ./test 2
Using FD 3
Got FD 4
# ./test 3
Using FD 3
Got FD 4
# ls /sys/bus/iio/devices/iio\:device0
buffer buffer0 buffer1 buffer2 buffer3 dev
in_voltage_sampling_frequency in_voltage_scale
in_voltage_scale_available
name of_node power scan_elements subsystem uevent
-------------------------------------------------------------------
iio:device0 has some fake kfifo buffers attached to an IIO device.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@analog.com>
Link: https://lore.kernel.org/r/20210215104043.91251-21-alexandru.ardelean@analog.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
108 lines
3.1 KiB
C
108 lines
3.1 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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/* The industrial I/O core function defs.
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*
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* Copyright (c) 2008 Jonathan Cameron
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*
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* These definitions are meant for use only within the IIO core, not individual
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* drivers.
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*/
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#ifndef _IIO_CORE_H_
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#define _IIO_CORE_H_
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#include <linux/kernel.h>
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#include <linux/device.h>
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struct iio_buffer;
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struct iio_chan_spec;
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struct iio_dev;
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extern struct device_type iio_device_type;
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struct iio_dev_buffer_pair {
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struct iio_dev *indio_dev;
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struct iio_buffer *buffer;
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};
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#define IIO_IOCTL_UNHANDLED 1
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struct iio_ioctl_handler {
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struct list_head entry;
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long (*ioctl)(struct iio_dev *indio_dev, struct file *filp,
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unsigned int cmd, unsigned long arg);
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};
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long iio_device_ioctl(struct iio_dev *indio_dev, struct file *filp,
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unsigned int cmd, unsigned long arg);
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void iio_device_ioctl_handler_register(struct iio_dev *indio_dev,
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struct iio_ioctl_handler *h);
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void iio_device_ioctl_handler_unregister(struct iio_ioctl_handler *h);
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int __iio_add_chan_devattr(const char *postfix,
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struct iio_chan_spec const *chan,
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ssize_t (*func)(struct device *dev,
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struct device_attribute *attr,
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char *buf),
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ssize_t (*writefunc)(struct device *dev,
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struct device_attribute *attr,
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const char *buf,
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size_t len),
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u64 mask,
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enum iio_shared_by shared_by,
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struct device *dev,
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struct iio_buffer *buffer,
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struct list_head *attr_list);
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void iio_free_chan_devattr_list(struct list_head *attr_list);
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int iio_device_register_sysfs_group(struct iio_dev *indio_dev,
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const struct attribute_group *group);
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ssize_t iio_format_value(char *buf, unsigned int type, int size, int *vals);
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/* Event interface flags */
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#define IIO_BUSY_BIT_POS 1
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#ifdef CONFIG_IIO_BUFFER
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struct poll_table_struct;
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__poll_t iio_buffer_poll_wrapper(struct file *filp,
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struct poll_table_struct *wait);
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ssize_t iio_buffer_read_wrapper(struct file *filp, char __user *buf,
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size_t n, loff_t *f_ps);
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int iio_buffers_alloc_sysfs_and_mask(struct iio_dev *indio_dev);
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void iio_buffers_free_sysfs_and_mask(struct iio_dev *indio_dev);
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#define iio_buffer_poll_addr (&iio_buffer_poll_wrapper)
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#define iio_buffer_read_outer_addr (&iio_buffer_read_wrapper)
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void iio_disable_all_buffers(struct iio_dev *indio_dev);
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void iio_buffer_wakeup_poll(struct iio_dev *indio_dev);
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void iio_buffers_put(struct iio_dev *indio_dev);
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#else
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#define iio_buffer_poll_addr NULL
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#define iio_buffer_read_outer_addr NULL
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static inline int iio_buffers_alloc_sysfs_and_mask(struct iio_dev *indio_dev)
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{
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return 0;
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}
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static inline void iio_buffers_free_sysfs_and_mask(struct iio_dev *indio_dev) {}
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static inline void iio_disable_all_buffers(struct iio_dev *indio_dev) {}
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static inline void iio_buffer_wakeup_poll(struct iio_dev *indio_dev) {}
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static inline void iio_buffers_put(struct iio_dev *indio_dev) {}
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#endif
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int iio_device_register_eventset(struct iio_dev *indio_dev);
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void iio_device_unregister_eventset(struct iio_dev *indio_dev);
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void iio_device_wakeup_eventset(struct iio_dev *indio_dev);
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struct iio_event_interface;
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bool iio_event_enabled(const struct iio_event_interface *ev_int);
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#endif
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