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') 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 --- drivers/gpio/gpiolib.c | 298 ++++++++++++++++++++++++++++++++++++++++++++++ include/uapi/linux/gpio.h | 54 ++++++++- 2 files changed, 347 insertions(+), 5 deletions(-) (limited to 'include/uapi') diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 5f2e73e99fa1..5239230ad075 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -22,6 +22,9 @@ #include #include #include +#include +#include +#include #include #include "gpiolib.h" @@ -501,6 +504,299 @@ out_free_lh: return ret; } +/* + * GPIO line event management + */ + +/** + * struct lineevent_state - contains the state of a userspace event + * @gdev: the GPIO device the event pertains to + * @label: consumer label used to tag descriptors + * @desc: the GPIO descriptor held by this event + * @eflags: the event flags this line was requested with + * @irq: the interrupt that trigger in response to events on this GPIO + * @wait: wait queue that handles blocking reads of events + * @events: KFIFO for the GPIO events + * @read_lock: mutex lock to protect reads from colliding with adding + * new events to the FIFO + */ +struct lineevent_state { + struct gpio_device *gdev; + const char *label; + struct gpio_desc *desc; + u32 eflags; + int irq; + wait_queue_head_t wait; + DECLARE_KFIFO(events, struct gpioevent_data, 16); + struct mutex read_lock; +}; + +static unsigned int lineevent_poll(struct file *filep, + struct poll_table_struct *wait) +{ + struct lineevent_state *le = filep->private_data; + unsigned int events = 0; + + poll_wait(filep, &le->wait, wait); + + if (!kfifo_is_empty(&le->events)) + events = POLLIN | POLLRDNORM; + + return events; +} + + +static ssize_t lineevent_read(struct file *filep, + char __user *buf, + size_t count, + loff_t *f_ps) +{ + struct lineevent_state *le = filep->private_data; + unsigned int copied; + int ret; + + if (count < sizeof(struct gpioevent_data)) + return -EINVAL; + + do { + if (kfifo_is_empty(&le->events)) { + if (filep->f_flags & O_NONBLOCK) + return -EAGAIN; + + ret = wait_event_interruptible(le->wait, + !kfifo_is_empty(&le->events)); + if (ret) + return ret; + } + + if (mutex_lock_interruptible(&le->read_lock)) + return -ERESTARTSYS; + ret = kfifo_to_user(&le->events, buf, count, &copied); + mutex_unlock(&le->read_lock); + + if (ret) + return ret; + + /* + * If we couldn't read anything from the fifo (a different + * thread might have been faster) we either return -EAGAIN if + * the file descriptor is non-blocking, otherwise we go back to + * sleep and wait for more data to arrive. + */ + if (copied == 0 && (filep->f_flags & O_NONBLOCK)) + return -EAGAIN; + + } while (copied == 0); + + return copied; +} + +static int lineevent_release(struct inode *inode, struct file *filep) +{ + struct lineevent_state *le = filep->private_data; + struct gpio_device *gdev = le->gdev; + + free_irq(le->irq, le); + gpiod_free(le->desc); + kfree(le->label); + kfree(le); + put_device(&gdev->dev); + return 0; +} + +static long lineevent_ioctl(struct file *filep, unsigned int cmd, + unsigned long arg) +{ + struct lineevent_state *le = filep->private_data; + void __user *ip = (void __user *)arg; + struct gpiohandle_data ghd; + + /* + * We can get the value for an event line but not set it, + * because it is input by definition. + */ + if (cmd == GPIOHANDLE_GET_LINE_VALUES_IOCTL) { + int val; + + val = gpiod_get_value_cansleep(le->desc); + if (val < 0) + return val; + ghd.values[0] = val; + + if (copy_to_user(ip, &ghd, sizeof(ghd))) + return -EFAULT; + + return 0; + } + return -EINVAL; +} + +#ifdef CONFIG_COMPAT +static long lineevent_ioctl_compat(struct file *filep, unsigned int cmd, + unsigned long arg) +{ + return lineevent_ioctl(filep, cmd, (unsigned long)compat_ptr(arg)); +} +#endif + +static const struct file_operations lineevent_fileops = { + .release = lineevent_release, + .read = lineevent_read, + .poll = lineevent_poll, + .owner = THIS_MODULE, + .llseek = noop_llseek, + .unlocked_ioctl = lineevent_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = lineevent_ioctl_compat, +#endif +}; + +irqreturn_t lineevent_irq_thread(int irq, void *p) +{ + struct lineevent_state *le = p; + struct gpioevent_data ge; + int ret; + + ge.timestamp = ktime_get_real_ns(); + + if (le->eflags & GPIOEVENT_REQUEST_BOTH_EDGES) { + int level = gpiod_get_value_cansleep(le->desc); + + if (level) + /* Emit low-to-high event */ + ge.id = GPIOEVENT_EVENT_RISING_EDGE; + else + /* Emit high-to-low event */ + ge.id = GPIOEVENT_EVENT_FALLING_EDGE; + } else if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE) { + /* Emit low-to-high event */ + ge.id = GPIOEVENT_EVENT_RISING_EDGE; + } else if (le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) { + /* Emit high-to-low event */ + ge.id = GPIOEVENT_EVENT_FALLING_EDGE; + } + + ret = kfifo_put(&le->events, ge); + if (ret != 0) + wake_up_poll(&le->wait, POLLIN); + + return IRQ_HANDLED; +} + +static int lineevent_create(struct gpio_device *gdev, void __user *ip) +{ + struct gpioevent_request eventreq; + struct lineevent_state *le; + struct gpio_desc *desc; + u32 offset; + u32 lflags; + u32 eflags; + int fd; + int ret; + int irqflags = 0; + + if (copy_from_user(&eventreq, ip, sizeof(eventreq))) + return -EFAULT; + + le = kzalloc(sizeof(*le), GFP_KERNEL); + if (!le) + return -ENOMEM; + le->gdev = gdev; + get_device(&gdev->dev); + + /* Make sure this is terminated */ + eventreq.consumer_label[sizeof(eventreq.consumer_label)-1] = '\0'; + if (strlen(eventreq.consumer_label)) { + le->label = kstrdup(eventreq.consumer_label, + GFP_KERNEL); + if (!le->label) { + ret = -ENOMEM; + goto out_free_le; + } + } + + offset = eventreq.lineoffset; + lflags = eventreq.handleflags; + eflags = eventreq.eventflags; + + /* This is just wrong: we don't look for events on output lines */ + if (lflags & GPIOHANDLE_REQUEST_OUTPUT) { + ret = -EINVAL; + goto out_free_label; + } + + desc = &gdev->descs[offset]; + ret = gpiod_request(desc, le->label); + if (ret) + goto out_free_desc; + le->desc = desc; + le->eflags = eflags; + + if (lflags & GPIOHANDLE_REQUEST_ACTIVE_LOW) + set_bit(FLAG_ACTIVE_LOW, &desc->flags); + if (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) + set_bit(FLAG_OPEN_DRAIN, &desc->flags); + if (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE) + set_bit(FLAG_OPEN_SOURCE, &desc->flags); + + ret = gpiod_direction_input(desc); + if (ret) + goto out_free_desc; + + le->irq = gpiod_to_irq(desc); + if (le->irq <= 0) { + ret = -ENODEV; + goto out_free_desc; + } + + if (eflags & GPIOEVENT_REQUEST_RISING_EDGE) + irqflags |= IRQF_TRIGGER_RISING; + if (eflags & GPIOEVENT_REQUEST_FALLING_EDGE) + irqflags |= IRQF_TRIGGER_FALLING; + irqflags |= IRQF_ONESHOT; + irqflags |= IRQF_SHARED; + + INIT_KFIFO(le->events); + init_waitqueue_head(&le->wait); + mutex_init(&le->read_lock); + + /* Request a thread to read the events */ + ret = request_threaded_irq(le->irq, + NULL, + lineevent_irq_thread, + irqflags, + le->label, + le); + if (ret) + goto out_free_desc; + + fd = anon_inode_getfd("gpio-event", + &lineevent_fileops, + le, + O_RDONLY | O_CLOEXEC); + if (fd < 0) { + ret = fd; + goto out_free_irq; + } + + eventreq.fd = fd; + if (copy_to_user(ip, &eventreq, sizeof(eventreq))) + return -EFAULT; + + return 0; + +out_free_irq: + free_irq(le->irq, le); +out_free_desc: + gpiod_free(le->desc); +out_free_label: + kfree(le->label); +out_free_le: + kfree(le); + put_device(&gdev->dev); + return ret; +} + /** * gpio_ioctl() - ioctl handler for the GPIO chardev */ @@ -578,6 +874,8 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) return 0; } else if (cmd == GPIO_GET_LINEHANDLE_IOCTL) { return linehandle_create(gdev, ip); + } else if (cmd == GPIO_GET_LINEEVENT_IOCTL) { + return lineevent_create(gdev, ip); } return -EINVAL; } 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