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61f922db72
This adds an ABI for listening to events on GPIO lines. The mechanism returns an anonymous file handle to a request to listen to a specific offset on a specific gpiochip. To fetch the stream of events from the file handle, userspace simply reads an event. - Events can be requested with the same flags as ordinary handles, i.e. open drain or open source. An ioctl() call GPIO_GET_LINEEVENT_IOCTL is issued indicating the desired line. - Events can be requested for falling edge events, rising edge events, or both. - All events are timestamped using the kernel real time nanosecond timestamp (the same as is used by IIO). - The supplied consumer label will appear in "lsgpio" listings of the lines, and in /proc/interrupts as the mechanism will request an interrupt from the gpio chip. - Events are not supported on gpiochips that do not serve interrupts (no legal .to_irq() call). The event interrupt is threaded to avoid any realtime problems. - It is possible to also directly read the current value of the registered GPIO line by issuing the same GPIOHANDLE_GET_LINE_VALUES_IOCTL as used by the line handles. Setting the value is not supported: we do not listen to events on output lines. This ABI is strongly influenced by Industrial I/O and surpasses the old sysfs ABI by providing proper precision timestamps, making it possible to set flags like open drain, and put consumer names on the GPIO lines. Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
158 lines
5.6 KiB
C
158 lines
5.6 KiB
C
/*
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* <linux/gpio.h> - userspace ABI for the GPIO character devices
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*
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* Copyright (C) 2016 Linus Walleij
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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#ifndef _UAPI_GPIO_H_
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#define _UAPI_GPIO_H_
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#include <linux/ioctl.h>
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#include <linux/types.h>
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/**
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* struct gpiochip_info - Information about a certain GPIO chip
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* @name: the Linux kernel name of this GPIO chip
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* @label: a functional name for this GPIO chip, such as a product
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* number, may be NULL
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* @lines: number of GPIO lines on this chip
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*/
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struct gpiochip_info {
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char name[32];
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char label[32];
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__u32 lines;
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};
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/* Informational flags */
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#define GPIOLINE_FLAG_KERNEL (1UL << 0) /* Line used by the kernel */
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#define GPIOLINE_FLAG_IS_OUT (1UL << 1)
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#define GPIOLINE_FLAG_ACTIVE_LOW (1UL << 2)
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#define GPIOLINE_FLAG_OPEN_DRAIN (1UL << 3)
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#define GPIOLINE_FLAG_OPEN_SOURCE (1UL << 4)
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/**
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* struct gpioline_info - Information about a certain GPIO line
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* @line_offset: the local offset on this GPIO device, fill this in when
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* requesting the line information from the kernel
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* @flags: various flags for this line
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* @name: the name of this GPIO line, such as the output pin of the line on the
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* chip, a rail or a pin header name on a board, as specified by the gpio
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* chip, may be NULL
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* @consumer: a functional name for the consumer of this GPIO line as set by
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* whatever is using it, will be NULL if there is no current user but may
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* also be NULL if the consumer doesn't set this up
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*/
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struct gpioline_info {
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__u32 line_offset;
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__u32 flags;
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char name[32];
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char consumer[32];
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};
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/* Maximum number of requested handles */
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#define GPIOHANDLES_MAX 64
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/* Linerequest flags */
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#define GPIOHANDLE_REQUEST_INPUT (1UL << 0)
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#define GPIOHANDLE_REQUEST_OUTPUT (1UL << 1)
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#define GPIOHANDLE_REQUEST_ACTIVE_LOW (1UL << 2)
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#define GPIOHANDLE_REQUEST_OPEN_DRAIN (1UL << 3)
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#define GPIOHANDLE_REQUEST_OPEN_SOURCE (1UL << 4)
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/**
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* struct gpiohandle_request - Information about a GPIO handle request
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* @lineoffsets: an array desired lines, specified by offset index for the
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* associated GPIO device
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* @flags: desired flags for the desired GPIO lines, such as
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* GPIOHANDLE_REQUEST_OUTPUT, GPIOHANDLE_REQUEST_ACTIVE_LOW etc, OR:ed
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* together. Note that even if multiple lines are requested, the same flags
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* must be applicable to all of them, if you want lines with individual
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* flags set, request them one by one. It is possible to select
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* a batch of input or output lines, but they must all have the same
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* characteristics, i.e. all inputs or all outputs, all active low etc
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* @default_values: if the GPIOHANDLE_REQUEST_OUTPUT is set for a requested
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* line, this specifies the default output value, should be 0 (low) or
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* 1 (high), anything else than 0 or 1 will be interpreted as 1 (high)
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* @consumer_label: a desired consumer label for the selected GPIO line(s)
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* such as "my-bitbanged-relay"
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* @lines: number of lines requested in this request, i.e. the number of
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* valid fields in the above arrays, set to 1 to request a single line
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* @fd: if successful this field will contain a valid anonymous file handle
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* after a GPIO_GET_LINEHANDLE_IOCTL operation, zero or negative value
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* means error
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*/
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struct gpiohandle_request {
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__u32 lineoffsets[GPIOHANDLES_MAX];
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__u32 flags;
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__u8 default_values[GPIOHANDLES_MAX];
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char consumer_label[32];
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__u32 lines;
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int fd;
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};
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/**
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* struct gpiohandle_data - Information of values on a GPIO handle
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* @values: when getting the state of lines this contains the current
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* state of a line, when setting the state of lines these should contain
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* the desired target state
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*/
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struct gpiohandle_data {
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__u8 values[GPIOHANDLES_MAX];
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};
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#define GPIOHANDLE_GET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x08, struct gpiohandle_data)
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#define GPIOHANDLE_SET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x09, struct gpiohandle_data)
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/* Eventrequest flags */
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#define GPIOEVENT_REQUEST_RISING_EDGE (1UL << 0)
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#define GPIOEVENT_REQUEST_FALLING_EDGE (1UL << 1)
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#define GPIOEVENT_REQUEST_BOTH_EDGES ((1UL << 0) | (1UL << 1))
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/**
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* struct gpioevent_request - Information about a GPIO event request
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* @lineoffset: the desired line to subscribe to events from, specified by
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* offset index for the associated GPIO device
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* @handleflags: desired handle flags for the desired GPIO line, such as
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* GPIOHANDLE_REQUEST_ACTIVE_LOW or GPIOHANDLE_REQUEST_OPEN_DRAIN
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* @eventflags: desired flags for the desired GPIO event line, such as
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* GPIOEVENT_REQUEST_RISING_EDGE or GPIOEVENT_REQUEST_FALLING_EDGE
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* @consumer_label: a desired consumer label for the selected GPIO line(s)
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* such as "my-listener"
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* @fd: if successful this field will contain a valid anonymous file handle
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* after a GPIO_GET_LINEEVENT_IOCTL operation, zero or negative value
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* means error
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*/
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struct gpioevent_request {
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__u32 lineoffset;
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__u32 handleflags;
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__u32 eventflags;
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char consumer_label[32];
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int fd;
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};
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/**
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* GPIO event types
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*/
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#define GPIOEVENT_EVENT_RISING_EDGE 0x01
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#define GPIOEVENT_EVENT_FALLING_EDGE 0x02
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/**
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* struct gpioevent_data - The actual event being pushed to userspace
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* @timestamp: best estimate of time of event occurrence, in nanoseconds
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* @id: event identifier
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*/
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struct gpioevent_data {
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__u64 timestamp;
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__u32 id;
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};
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#define GPIO_GET_CHIPINFO_IOCTL _IOR(0xB4, 0x01, struct gpiochip_info)
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#define GPIO_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x02, struct gpioline_info)
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#define GPIO_GET_LINEHANDLE_IOCTL _IOWR(0xB4, 0x03, struct gpiohandle_request)
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#define GPIO_GET_LINEEVENT_IOCTL _IOWR(0xB4, 0x04, struct gpioevent_request)
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#endif /* _UAPI_GPIO_H_ */
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