Re: [PATCH v5 13/17] iio: buffer: add ioctl() to support opening extra buffers for IIO device
On Sun, Feb 14, 2021 at 4:38 PM Jonathan Cameron wrote:
>
> On Thu, 11 Feb 2021 14:24:48 +0200
> Alexandru Ardelean wrote:
>
> > 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
> > #include
> > #include
> > #include
> > #include > #include
> >
> > #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, );
> > 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
>
> There are a few corners of this that I'm not quite confident enough to just
> 'fix up' whilst applying.
>
>
> > ---
> > drivers/iio/iio_core.h| 12 +--
> > drivers/iio/industrialio-buffer.c | 138 --
> > drivers/iio/industrialio-core.c | 1 +
> > include/linux/iio/buffer_impl.h | 5 ++
> > include/linux/iio/iio-opaque.h| 2 +
> > include/uapi/linux/iio/buffer.h | 10 +++
> > 6 files changed, 157 insertions(+), 11 deletions(-)
> > create mode 100644 include/uapi/linux/iio/buffer.h
> >
> > diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
> > index 4690c3240a5d..88db1feb5857 100644
> > --- a/drivers/iio/iio_core.h
> > +++ b/drivers/iio/iio_core.h
> > @@ -64,16 +64,16 @@ ssize_t iio_format_value(char *buf, unsigned int type,
> > int size, int *vals);
> > #ifdef CONFIG_IIO_BUFFER
> > struct poll_table_struct;
> >
> > -__poll_t iio_buffer_poll(struct file *filp,
> > - struct poll_table_struct *wait);
> > -ssize_t iio_buffer_read_outer(struct file *filp, char __user *buf,
> > - size_t n, loff_t *f_ps);
> > +__poll_t iio_buffer_poll_wrapper(struct file *filp,
> > + struct poll_table_struct *wait);
> > +ssize_t iio_buffer_read_wrapper(struct file *filp, char __user *buf,
> > + size_t n, loff_t *f_ps);
> >
> > int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev);
> > void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev);
> >
> > -#define iio_buffer_poll_addr (_buffer_poll)
> > -#define iio_buffer_read_outer_addr (_buffer_read_outer)
> > +#define iio_buffer_poll_addr (_buffer_poll_wrapper)
> > +#define iio_buffer_read_outer_addr (_buffer_read_wrapper)
> >
> > void iio_disable_all_buffers(struct iio_dev *indio_dev);
> > void iio_buffer_wakeup_poll(struct iio_dev *indio_dev);
> > diff --git a/drivers/iio/industrialio-buffer.c
> > b/drivers/iio/industrialio-buffer.c
> > index 1e8e4c2ff00e..3aa6702a5811 100644
> > ---
Re: [PATCH v5 13/17] iio: buffer: add ioctl() to support opening extra buffers for IIO device
On Thu, 11 Feb 2021 14:24:48 +0200
Alexandru Ardelean wrote:
> 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
> #include
> #include
> #include
> #include #include
>
> #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, );
> 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
There are a few corners of this that I'm not quite confident enough to just
'fix up' whilst applying.
> ---
> drivers/iio/iio_core.h| 12 +--
> drivers/iio/industrialio-buffer.c | 138 --
> drivers/iio/industrialio-core.c | 1 +
> include/linux/iio/buffer_impl.h | 5 ++
> include/linux/iio/iio-opaque.h| 2 +
> include/uapi/linux/iio/buffer.h | 10 +++
> 6 files changed, 157 insertions(+), 11 deletions(-)
> create mode 100644 include/uapi/linux/iio/buffer.h
>
> diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
> index 4690c3240a5d..88db1feb5857 100644
> --- a/drivers/iio/iio_core.h
> +++ b/drivers/iio/iio_core.h
> @@ -64,16 +64,16 @@ ssize_t iio_format_value(char *buf, unsigned int type,
> int size, int *vals);
> #ifdef CONFIG_IIO_BUFFER
> struct poll_table_struct;
>
> -__poll_t iio_buffer_poll(struct file *filp,
> - struct poll_table_struct *wait);
> -ssize_t iio_buffer_read_outer(struct file *filp, char __user *buf,
> - size_t n, loff_t *f_ps);
> +__poll_t iio_buffer_poll_wrapper(struct file *filp,
> + struct poll_table_struct *wait);
> +ssize_t iio_buffer_read_wrapper(struct file *filp, char __user *buf,
> + size_t n, loff_t *f_ps);
>
> int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev);
> void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev);
>
> -#define iio_buffer_poll_addr (_buffer_poll)
> -#define iio_buffer_read_outer_addr (_buffer_read_outer)
> +#define iio_buffer_poll_addr (_buffer_poll_wrapper)
> +#define iio_buffer_read_outer_addr (_buffer_read_wrapper)
>
> void iio_disable_all_buffers(struct iio_dev *indio_dev);
> void iio_buffer_wakeup_poll(struct iio_dev *indio_dev);
> diff --git a/drivers/iio/industrialio-buffer.c
> b/drivers/iio/industrialio-buffer.c
> index 1e8e4c2ff00e..3aa6702a5811 100644
> --- a/drivers/iio/industrialio-buffer.c
> +++ b/drivers/iio/industrialio-buffer.c
> @@ -9,6 +9,7 @@
> * - Better memory allocation techniques?
> * - Alternative access techniques?
> */
> +#include
> #include
> #include
> #include
> @@ -89,7 +90,7 @@ static bool iio_buffer_ready(struct iio_dev *indio_dev,
> struct iio_buffer
[PATCH v5 13/17] iio: buffer: add ioctl() to support opening extra buffers for IIO device
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
#include
#include
#include
#include
#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, );
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
---
drivers/iio/iio_core.h| 12 +--
drivers/iio/industrialio-buffer.c | 138 --
drivers/iio/industrialio-core.c | 1 +
include/linux/iio/buffer_impl.h | 5 ++
include/linux/iio/iio-opaque.h| 2 +
include/uapi/linux/iio/buffer.h | 10 +++
6 files changed, 157 insertions(+), 11 deletions(-)
create mode 100644 include/uapi/linux/iio/buffer.h
diff --git a/drivers/iio/iio_core.h b/drivers/iio/iio_core.h
index 4690c3240a5d..88db1feb5857 100644
--- a/drivers/iio/iio_core.h
+++ b/drivers/iio/iio_core.h
@@ -64,16 +64,16 @@ ssize_t iio_format_value(char *buf, unsigned int type, int
size, int *vals);
#ifdef CONFIG_IIO_BUFFER
struct poll_table_struct;
-__poll_t iio_buffer_poll(struct file *filp,
-struct poll_table_struct *wait);
-ssize_t iio_buffer_read_outer(struct file *filp, char __user *buf,
- size_t n, loff_t *f_ps);
+__poll_t iio_buffer_poll_wrapper(struct file *filp,
+struct poll_table_struct *wait);
+ssize_t iio_buffer_read_wrapper(struct file *filp, char __user *buf,
+ size_t n, loff_t *f_ps);
int iio_buffer_alloc_sysfs_and_mask(struct iio_dev *indio_dev);
void iio_buffer_free_sysfs_and_mask(struct iio_dev *indio_dev);
-#define iio_buffer_poll_addr (_buffer_poll)
-#define iio_buffer_read_outer_addr (_buffer_read_outer)
+#define iio_buffer_poll_addr (_buffer_poll_wrapper)
+#define iio_buffer_read_outer_addr (_buffer_read_wrapper)
void iio_disable_all_buffers(struct iio_dev *indio_dev);
void iio_buffer_wakeup_poll(struct iio_dev *indio_dev);
diff --git a/drivers/iio/industrialio-buffer.c
b/drivers/iio/industrialio-buffer.c
index 1e8e4c2ff00e..3aa6702a5811 100644
--- a/drivers/iio/industrialio-buffer.c
+++ b/drivers/iio/industrialio-buffer.c
@@ -9,6 +9,7 @@
* - Better memory allocation techniques?
* - Alternative access techniques?
*/
+#include
#include
#include
#include
@@ -89,7 +90,7 @@ static bool iio_buffer_ready(struct iio_dev *indio_dev,
struct iio_buffer *buf,
}
/**
- * iio_buffer_read_outer() - chrdev read for buffer access
+ * iio_buffer_read() - chrdev read for buffer access
* @filp: File structure pointer for the char device
* @buf: Destination buffer for iio buffer read
* @n: First n bytes to read
@@ -101,8 +102,8 @@ static bool iio_buffer_ready(struct iio_dev *indio_dev,
struct iio_buffer *buf,
* Return: negative values corresponding to error codes or ret != 0
*
