From d7c51b47ac11e66f547b55640405c1c474642d72 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Tue, 26 Apr 2016 10:35:29 +0200 Subject: gpio: userspace ABI for reading/writing GPIO lines 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 Signed-off-by: Linus Walleij --- include/uapi/linux/gpio.h | 61 ++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 58 insertions(+), 3 deletions(-) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/gpio.h b/include/uapi/linux/gpio.h index d0a3cac72250..21905531dcf4 100644 --- a/include/uapi/linux/gpio.h +++ b/include/uapi/linux/gpio.h @@ -1,7 +1,7 @@ /* * - userspace ABI for the GPIO character devices * - * Copyright (C) 2015 Linus Walleij + * Copyright (C) 2016 Linus Walleij * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 as published by @@ -26,8 +26,8 @@ struct gpiochip_info { __u32 lines; }; -/* Line is in use by the kernel */ -#define GPIOLINE_FLAG_KERNEL (1UL << 0) +/* Informational flags */ +#define GPIOLINE_FLAG_KERNEL (1UL << 0) /* Line used by the kernel */ #define GPIOLINE_FLAG_IS_OUT (1UL << 1) #define GPIOLINE_FLAG_ACTIVE_LOW (1UL << 2) #define GPIOLINE_FLAG_OPEN_DRAIN (1UL << 3) @@ -52,7 +52,62 @@ struct gpioline_info { char consumer[32]; }; +/* Maximum number of requested handles */ +#define GPIOHANDLES_MAX 64 + +/* Request flags */ +#define GPIOHANDLE_REQUEST_INPUT (1UL << 0) +#define GPIOHANDLE_REQUEST_OUTPUT (1UL << 1) +#define GPIOHANDLE_REQUEST_ACTIVE_LOW (1UL << 2) +#define GPIOHANDLE_REQUEST_OPEN_DRAIN (1UL << 3) +#define GPIOHANDLE_REQUEST_OPEN_SOURCE (1UL << 4) + +/** + * struct gpiohandle_request - Information about a GPIO handle request + * @lineoffsets: an array desired lines, specified by offset index for the + * associated GPIO device + * @flags: desired flags for the desired GPIO lines, such as + * GPIOHANDLE_REQUEST_OUTPUT, GPIOHANDLE_REQUEST_ACTIVE_LOW etc, OR:ed + * together. Note that even if multiple lines are requested, the same flags + * must be applicable to all of them, if you want lines with individual + * flags set, request them one by one. It is possible to select + * a batch of input or output lines, but they must all have the same + * characteristics, i.e. all inputs or all outputs, all active low etc + * @default_values: if the GPIOHANDLE_REQUEST_OUTPUT is set for a requested + * line, this specifies the default output value, should be 0 (low) or + * 1 (high), anything else than 0 or 1 will be interpreted as 1 (high) + * @consumer_label: a desired consumer label for the selected GPIO line(s) + * such as "my-bitbanged-relay" + * @lines: number of lines requested in this request, i.e. the number of + * valid fields in the above arrays, set to 1 to request a single line + * @fd: if successful this field will contain a valid anonymous file handle + * after a GPIO_GET_LINEHANDLE_IOCTL operation, zero or negative value + * means error + */ +struct gpiohandle_request { + __u32 lineoffsets[GPIOHANDLES_MAX]; + __u32 flags; + __u8 default_values[GPIOHANDLES_MAX]; + char consumer_label[32]; + __u32 lines; + int fd; +}; + #define GPIO_GET_CHIPINFO_IOCTL _IOR(0xB4, 0x01, struct gpiochip_info) #define GPIO_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x02, struct gpioline_info) +#define GPIO_GET_LINEHANDLE_IOCTL _IOWR(0xB4, 0x03, struct gpiohandle_request) + +/** + * struct gpiohandle_data - Information of values on a GPIO handle + * @values: when getting the state of lines this contains the current + * state of a line, when setting the state of lines these should contain + * the desired target state + */ +struct gpiohandle_data { + __u8 values[GPIOHANDLES_MAX]; +}; + +#define GPIOHANDLE_GET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x08, struct gpiohandle_data) +#define GPIOHANDLE_SET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x09, struct gpiohandle_data) #endif /* _UAPI_GPIO_H_ */ -- cgit v1.2.3 From 61f922db72216b00386581c851db9c9095961522 Mon Sep 17 00:00:00 2001 From: Linus Walleij Date: Thu, 2 Jun 2016 11:30:15 +0200 Subject: gpio: userspace ABI for reading GPIO line events 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 --- include/uapi/linux/gpio.h | 54 ++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 49 insertions(+), 5 deletions(-) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/gpio.h b/include/uapi/linux/gpio.h index 21905531dcf4..333d3544c964 100644 --- a/include/uapi/linux/gpio.h +++ b/include/uapi/linux/gpio.h @@ -55,7 +55,7 @@ struct gpioline_info { /* Maximum number of requested handles */ #define GPIOHANDLES_MAX 64 -/* Request flags */ +/* Linerequest flags */ #define GPIOHANDLE_REQUEST_INPUT (1UL << 0) #define GPIOHANDLE_REQUEST_OUTPUT (1UL << 1) #define GPIOHANDLE_REQUEST_ACTIVE_LOW (1UL << 2) @@ -93,10 +93,6 @@ struct gpiohandle_request { int fd; }; -#define GPIO_GET_CHIPINFO_IOCTL _IOR(0xB4, 0x01, struct gpiochip_info) -#define GPIO_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x02, struct gpioline_info) -#define GPIO_GET_LINEHANDLE_IOCTL _IOWR(0xB4, 0x03, struct gpiohandle_request) - /** * struct gpiohandle_data - Information of values on a GPIO handle * @values: when getting the state of lines this contains the current @@ -110,4 +106,52 @@ struct gpiohandle_data { #define GPIOHANDLE_GET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x08, struct gpiohandle_data) #define GPIOHANDLE_SET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x09, struct gpiohandle_data) +/* Eventrequest flags */ +#define GPIOEVENT_REQUEST_RISING_EDGE (1UL << 0) +#define GPIOEVENT_REQUEST_FALLING_EDGE (1UL << 1) +#define GPIOEVENT_REQUEST_BOTH_EDGES ((1UL << 0) | (1UL << 1)) + +/** + * struct gpioevent_request - Information about a GPIO event request + * @lineoffset: the desired line to subscribe to events from, specified by + * offset index for the associated GPIO device + * @handleflags: desired handle flags for the desired GPIO line, such as + * GPIOHANDLE_REQUEST_ACTIVE_LOW or GPIOHANDLE_REQUEST_OPEN_DRAIN + * @eventflags: desired flags for the desired GPIO event line, such as + * GPIOEVENT_REQUEST_RISING_EDGE or GPIOEVENT_REQUEST_FALLING_EDGE + * @consumer_label: a desired consumer label for the selected GPIO line(s) + * such as "my-listener" + * @fd: if successful this field will contain a valid anonymous file handle + * after a GPIO_GET_LINEEVENT_IOCTL operation, zero or negative value + * means error + */ +struct gpioevent_request { + __u32 lineoffset; + __u32 handleflags; + __u32 eventflags; + char consumer_label[32]; + int fd; +}; + +/** + * GPIO event types + */ +#define GPIOEVENT_EVENT_RISING_EDGE 0x01 +#define GPIOEVENT_EVENT_FALLING_EDGE 0x02 + +/** + * struct gpioevent_data - The actual event being pushed to userspace + * @timestamp: best estimate of time of event occurrence, in nanoseconds + * @id: event identifier + */ +struct gpioevent_data { + __u64 timestamp; + __u32 id; +}; + +#define GPIO_GET_CHIPINFO_IOCTL _IOR(0xB4, 0x01, struct gpiochip_info) +#define GPIO_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x02, struct gpioline_info) +#define GPIO_GET_LINEHANDLE_IOCTL _IOWR(0xB4, 0x03, struct gpiohandle_request) +#define GPIO_GET_LINEEVENT_IOCTL _IOWR(0xB4, 0x04, struct gpioevent_request) + #endif /* _UAPI_GPIO_H_ */ -- cgit v1.2.3