d7c51b47ac
This adds a userspace ABI for reading and writing GPIO lines. The mechanism returns an anonymous file handle to a request to read/write n offsets from a gpiochip. This file handle in turn accepts two ioctl()s: one that reads and one that writes values to the selected lines. - Handles can be requested as input/output, active low, open drain, open source, however when you issue a request for n lines with GPIO_GET_LINEHANDLE_IOCTL, they must all have the same flags, i.e. all inputs or all outputs, all open drain etc. If a granular control of the flags for each line is desired, they need to be requested individually, not in a batch. - The GPIOHANDLE_GET_LINE_VALUES_IOCTL read ioctl() can be issued also to output lines to verify that the hardware is in the expected state. - It reads and writes up to GPIOHANDLES_MAX lines at once, utilizing the .set_multiple() call in the driver if possible, making the call efficient if several lines can be written with a single register update. The limitation of GPIOHANDLES_MAX to 64 lines is done under the assumption that we may expect hardware that can issue a transaction updating 64 bits at an instant but unlikely anything larger than that. ChangeLog v2->v3: - Use gpiod_get_value_cansleep() so we support also slowpath GPIO drivers. - Fix up the UAPI docs kerneldoc. - Allocate the anonymous fd last, so that the release function don't get called until that point of something fails. After this point, skip the errorpath. ChangeLog v1->v2: - Handle ioctl_compat() properly based on a similar patch to the other ioctl() handling code. - Use _IOWR() as we pass pointers both in and out of the ioctl() - Use kmalloc() and kfree() for the linehandled, do not try to be fancy with devm_* it doesn't work the way I thought. - Fix const-correctness on the linehandle name field. Acked-by: Michael Welling <mwelling@ieee.org> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
114 lines
4.1 KiB
C
114 lines
4.1 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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/* Request 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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#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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/**
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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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#endif /* _UAPI_GPIO_H_ */
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