diff options
| -rw-r--r-- | drivers/gpio/gpiolib.c | 298 | ||||
| -rw-r--r-- | include/uapi/linux/gpio.h | 54 |
2 files changed, 347 insertions, 5 deletions
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 <linux/uaccess.h> #include <linux/compat.h> #include <linux/anon_inodes.h> +#include <linux/kfifo.h> +#include <linux/poll.h> +#include <linux/timekeeping.h> #include <uapi/linux/gpio.h> #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_ */ |