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d1b3b9c70e
Add `comedi_open_from(path, from)` and `comedi_close_from(dev, from)` as variants of the existing `comedi_from(path)` and `comedi_close(dev)`. The additional `from` parameter is a minor device number that tells the function that the COMEDI device is being opened or closed from another COMEDI device if the value is in the range [0, `COMEDI_NUM_BOARD_MINORS`-1]. In that case the function will refuse to open the device if it would lead to a chain of devices opening each other. (It will also impose a limit on the number of simultaneous opens from one device to another because we need to count those.) The new functions are intended to be used by the "comedi_bond" driver, which is the only driver that uses the existing `comedi_open()` and `comedi_close()` functions. The new functions will be used to avoid some possible deadlock situations. Replace the existing, exported `comedi_open()` and `comedi_close()` functions with inline wrapper functions that call the newly exported `comedi_open_from()` and `comedi_close_from()` functions. Signed-off-by: Ian Abbott <abbotti@mev.co.uk> Link: https://patch.msgid.link/20251027153748.4569-2-abbotti@mev.co.uk Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
57 lines
1.6 KiB
C
57 lines
1.6 KiB
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* comedilib.h
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* Header file for kcomedilib
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*
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* COMEDI - Linux Control and Measurement Device Interface
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* Copyright (C) 1998-2001 David A. Schleef <ds@schleef.org>
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*/
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#ifndef _LINUX_COMEDILIB_H
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#define _LINUX_COMEDILIB_H
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struct comedi_device *comedi_open_from(const char *path, int from);
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/**
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* comedi_open() - Open a COMEDI device from the kernel
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* @filename: Fake pathname of the form "/dev/comediN".
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*
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* Converts @filename to a COMEDI device number and "opens" it if it exists
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* and is attached to a low-level COMEDI driver.
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*
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* Return: A pointer to the COMEDI device on success.
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* Return %NULL on failure.
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*/
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static inline struct comedi_device *comedi_open(const char *path)
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{
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return comedi_open_from(path, -1);
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}
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int comedi_close_from(struct comedi_device *dev, int from);
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/**
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* comedi_close() - Close a COMEDI device from the kernel
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* @dev: COMEDI device.
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*
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* Closes a COMEDI device previously opened by comedi_open().
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*
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* Returns: 0
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*/
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static inline int comedi_close(struct comedi_device *dev)
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{
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return comedi_close_from(dev, -1);
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}
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int comedi_dio_get_config(struct comedi_device *dev, unsigned int subdev,
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unsigned int chan, unsigned int *io);
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int comedi_dio_config(struct comedi_device *dev, unsigned int subdev,
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unsigned int chan, unsigned int io);
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int comedi_dio_bitfield2(struct comedi_device *dev, unsigned int subdev,
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unsigned int mask, unsigned int *bits,
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unsigned int base_channel);
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int comedi_find_subdevice_by_type(struct comedi_device *dev, int type,
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unsigned int subd);
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int comedi_get_n_channels(struct comedi_device *dev, unsigned int subdevice);
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#endif
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