From f73f7f4da581875f9b1f2fb8ebd1ab15ed634488 Mon Sep 17 00:00:00 2001 From: Alexandru Ardelean Date: Mon, 15 Feb 2021 12:40:39 +0200 Subject: [PATCH] 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, &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 Link: https://lore.kernel.org/r/20210215104043.91251-21-alexandru.ardelean@analog.com Signed-off-by: Jonathan Cameron --- drivers/iio/iio_core.h | 12 ++-- drivers/iio/industrialio-buffer.c | 144 ++++++++++++++++++++++++++++++++++++-- include/linux/iio/buffer_impl.h | 5 ++ include/linux/iio/iio-opaque.h | 2 + include/uapi/linux/iio/buffer.h | 10 +++ 5 files changed, 162 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 7990c75..062fe16 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_buffers_alloc_sysfs_and_mask(struct iio_dev *indio_dev); void iio_buffers_free_sysfs_and_mask(struct iio_dev *indio_dev); -#define iio_buffer_poll_addr (&iio_buffer_poll) -#define iio_buffer_read_outer_addr (&iio_buffer_read_outer) +#define iio_buffer_poll_addr (&iio_buffer_poll_wrapper) +#define iio_buffer_read_outer_addr (&iio_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 b60c2e6..a48e494 100644 --- a/drivers/iio/industrialio-buffer.c +++ b/drivers/iio/industrialio-buffer.c @@ -9,9 +9,11 @@ * - Better memory allocation techniques? * - Alternative access techniques? */ +#include #include #include #include +#include #include #include #include @@ -89,7 +91,7 @@ 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 +103,8 @@ static bool iio_buffer_ready(struct iio_dev *indio_dev, struct iio_buffer *buf, * Return: negative values corresponding to error codes or ret != 0 * for ending the reading activity **/ -ssize_t iio_buffer_read_outer(struct file *filp, char __user *buf, - size_t n, loff_t *f_ps) +static ssize_t iio_buffer_read(struct file *filp, char __user *buf, + size_t n, loff_t *f_ps) { struct iio_dev_buffer_pair *ib = filp->private_data; struct iio_buffer *rb = ib->buffer; @@ -168,8 +170,8 @@ ssize_t iio_buffer_read_outer(struct file *filp, char __user *buf, * Return: (EPOLLIN | EPOLLRDNORM) if data is available for reading * or 0 for other cases */ -__poll_t iio_buffer_poll(struct file *filp, - struct poll_table_struct *wait) +static __poll_t iio_buffer_poll(struct file *filp, + struct poll_table_struct *wait) { struct iio_dev_buffer_pair *ib = filp->private_data; struct iio_buffer *rb = ib->buffer; @@ -184,6 +186,32 @@ __poll_t iio_buffer_poll(struct file *filp, return 0; } +ssize_t iio_buffer_read_wrapper(struct file *filp, char __user *buf, + size_t n, loff_t *f_ps) +{ + struct iio_dev_buffer_pair *ib = filp->private_data; + struct iio_buffer *rb = ib->buffer; + + /* check if buffer was opened through new API */ + if (test_bit(IIO_BUSY_BIT_POS, &rb->flags)) + return -EBUSY; + + return iio_buffer_read(filp, buf, n, f_ps); +} + +__poll_t iio_buffer_poll_wrapper(struct file *filp, + struct poll_table_struct *wait) +{ + struct iio_dev_buffer_pair *ib = filp->private_data; + struct iio_buffer *rb = ib->buffer; + + /* check if buffer was opened through new API */ + if (test_bit(IIO_BUSY_BIT_POS, &rb->flags)) + return 0; + + return iio_buffer_poll(filp, wait); +} + /** * iio_buffer_wakeup_poll - Wakes up the buffer waitqueue * @indio_dev: The IIO device @@ -1344,6 +1372,96 @@ static void iio_buffer_unregister_legacy_sysfs_groups(struct iio_dev *indio_dev) kfree(iio_dev_opaque->legacy_scan_el_group.attrs); } +static int iio_buffer_chrdev_release(struct inode *inode, struct file *filep) +{ + struct iio_dev_buffer_pair *ib = filep->private_data; + struct iio_dev *indio_dev = ib->indio_dev; + struct iio_buffer *buffer = ib->buffer; + + wake_up(&buffer->pollq); + + kfree(ib); + clear_bit(IIO_BUSY_BIT_POS, &buffer->flags); + iio_device_put(indio_dev); + + return 0; +} + +static const struct file_operations iio_buffer_chrdev_fileops = { + .owner = THIS_MODULE, + .llseek = noop_llseek, + .read = iio_buffer_read, + .poll = iio_buffer_poll, + .release = iio_buffer_chrdev_release, +}; + +static long iio_device_buffer_getfd(struct iio_dev *indio_dev, unsigned long arg) +{ + struct iio_dev_opaque *iio_dev_opaque = to_iio_dev_opaque(indio_dev); + int __user *ival = (int __user *)arg; + struct iio_dev_buffer_pair *ib; + struct iio_buffer *buffer; + int fd, idx, ret; + + if (copy_from_user(&idx, ival, sizeof(idx))) + return -EFAULT; + + if (idx >= iio_dev_opaque->attached_buffers_cnt) + return -ENODEV; + + iio_device_get(indio_dev); + + buffer = iio_dev_opaque->attached_buffers[idx]; + + if (test_and_set_bit(IIO_BUSY_BIT_POS, &buffer->flags)) { + ret = -EBUSY; + goto error_iio_dev_put; + } + + ib = kzalloc(sizeof(*ib), GFP_KERNEL); + if (!ib) { + ret = -ENOMEM; + goto error_clear_busy_bit; + } + + ib->indio_dev = indio_dev; + ib->buffer = buffer; + + fd = anon_inode_getfd("iio:buffer", &iio_buffer_chrdev_fileops, + ib, O_RDWR | O_CLOEXEC); + if (fd < 0) { + ret = fd; + goto error_free_ib; + } + + if (copy_to_user(ival, &fd, sizeof(fd))) { + put_unused_fd(fd); + ret = -EFAULT; + goto error_free_ib; + } + + return fd; + +error_free_ib: + kfree(ib); +error_clear_busy_bit: + clear_bit(IIO_BUSY_BIT_POS, &buffer->flags); +error_iio_dev_put: + iio_device_put(indio_dev); + return ret; +} + +static long iio_device_buffer_ioctl(struct iio_dev *indio_dev, struct file *filp, + unsigned int cmd, unsigned long arg) +{ + switch (cmd) { + case IIO_BUFFER_GET_FD_IOCTL: + return iio_device_buffer_getfd(indio_dev, arg); + default: + return IIO_IOCTL_UNHANDLED; + } +} + static int __iio_buffer_alloc_sysfs_and_mask(struct iio_buffer *buffer, struct iio_dev *indio_dev, int index) @@ -1473,6 +1591,7 @@ int iio_buffers_alloc_sysfs_and_mask(struct iio_dev *indio_dev) struct iio_buffer *buffer; int unwind_idx; int ret, i; + size_t sz; channels = indio_dev->channels; if (channels) { @@ -1494,6 +1613,18 @@ int iio_buffers_alloc_sysfs_and_mask(struct iio_dev *indio_dev) goto error_unwind_sysfs_and_mask; } } + unwind_idx = iio_dev_opaque->attached_buffers_cnt - 1; + + sz = sizeof(*(iio_dev_opaque->buffer_ioctl_handler)); + iio_dev_opaque->buffer_ioctl_handler = kzalloc(sz, GFP_KERNEL); + if (!iio_dev_opaque->buffer_ioctl_handler) { + ret = -ENOMEM; + goto error_unwind_sysfs_and_mask; + } + + iio_dev_opaque->buffer_ioctl_handler->ioctl = iio_device_buffer_ioctl; + iio_device_ioctl_handler_register(indio_dev, + iio_dev_opaque->buffer_ioctl_handler); return 0; @@ -1515,6 +1646,9 @@ void iio_buffers_free_sysfs_and_mask(struct iio_dev *indio_dev) if (!iio_dev_opaque->attached_buffers_cnt) return; + iio_device_ioctl_handler_unregister(iio_dev_opaque->buffer_ioctl_handler); + kfree(iio_dev_opaque->buffer_ioctl_handler); + iio_buffer_unregister_legacy_sysfs_groups(indio_dev); for (i = iio_dev_opaque->attached_buffers_cnt - 1; i >= 0; i--) { diff --git a/include/linux/iio/buffer_impl.h b/include/linux/iio/buffer_impl.h index 768b90c..245b329 100644 --- a/include/linux/iio/buffer_impl.h +++ b/include/linux/iio/buffer_impl.h @@ -6,6 +6,8 @@ #ifdef CONFIG_IIO_BUFFER +#include + struct iio_dev; struct iio_buffer; @@ -72,6 +74,9 @@ struct iio_buffer { /** @length: Number of datums in buffer. */ unsigned int length; + /** @flags: File ops flags including busy flag. */ + unsigned long flags; + /** @bytes_per_datum: Size of individual datum including timestamp. */ size_t bytes_per_datum; diff --git a/include/linux/iio/iio-opaque.h b/include/linux/iio/iio-opaque.h index b6ebc04..32addd5 100644 --- a/include/linux/iio/iio-opaque.h +++ b/include/linux/iio/iio-opaque.h @@ -9,6 +9,7 @@ * @event_interface: event chrdevs associated with interrupt lines * @attached_buffers: array of buffers statically attached by the driver * @attached_buffers_cnt: number of buffers in the array of statically attached buffers + * @buffer_ioctl_handler: ioctl() handler for this IIO device's buffer interface * @buffer_list: list of all buffers currently attached * @channel_attr_list: keep track of automatically created channel * attributes @@ -28,6 +29,7 @@ struct iio_dev_opaque { struct iio_event_interface *event_interface; struct iio_buffer **attached_buffers; unsigned int attached_buffers_cnt; + struct iio_ioctl_handler *buffer_ioctl_handler; struct list_head buffer_list; struct list_head channel_attr_list; struct attribute_group chan_attr_group; diff --git a/include/uapi/linux/iio/buffer.h b/include/uapi/linux/iio/buffer.h new file mode 100644 index 0000000..1393903 --- /dev/null +++ b/include/uapi/linux/iio/buffer.h @@ -0,0 +1,10 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* industrial I/O buffer definitions needed both in and out of kernel + */ + +#ifndef _UAPI_IIO_BUFFER_H_ +#define _UAPI_IIO_BUFFER_H_ + +#define IIO_BUFFER_GET_FD_IOCTL _IOWR('i', 0x91, int) + +#endif /* _UAPI_IIO_BUFFER_H_ */ -- 2.7.4