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-rw-r--r--drivers/gpio/gpiolib.c298
1 files changed, 298 insertions, 0 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;
}
generated by cgit v1.2.3-58-ga151 (git 2.39.0) at 2024-12-28 20:20:31 +0000