diff options
| -rw-r--r-- | drivers/gpio/gpiolib.c | 186 | ||||
| -rw-r--r-- | drivers/gpio/gpiolib.h | 1 | ||||
| -rw-r--r-- | include/uapi/linux/gpio.h | 30 |
3 files changed, 209 insertions, 8 deletions
diff --git a/drivers/gpio/gpiolib.c b/drivers/gpio/gpiolib.c index 443321f9cf63..f73077f26eff 100644 --- a/drivers/gpio/gpiolib.c +++ b/drivers/gpio/gpiolib.c @@ -546,6 +546,9 @@ static long linehandle_set_config(struct linehandle_state *lh, if (ret) return ret; } + + atomic_notifier_call_chain(&desc->gdev->notifier, + GPIOLINE_CHANGED_CONFIG, desc); } return 0; } @@ -1201,14 +1204,25 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc, spin_unlock_irqrestore(&gpio_lock, flags); } +struct gpio_chardev_data { + struct gpio_device *gdev; + wait_queue_head_t wait; + DECLARE_KFIFO(events, struct gpioline_info_changed, 32); + struct notifier_block lineinfo_changed_nb; + unsigned long *watched_lines; +}; + /* * gpio_ioctl() - ioctl handler for the GPIO chardev */ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) { - struct gpio_device *gdev = filp->private_data; + struct gpio_chardev_data *priv = filp->private_data; + struct gpio_device *gdev = priv->gdev; struct gpio_chip *chip = gdev->chip; void __user *ip = (void __user *)arg; + struct gpio_desc *desc; + __u32 offset; /* We fail any subsequent ioctl():s when the chip is gone */ if (!chip) @@ -1230,9 +1244,9 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) if (copy_to_user(ip, &chipinfo, sizeof(chipinfo))) return -EFAULT; return 0; - } else if (cmd == GPIO_GET_LINEINFO_IOCTL) { + } else if (cmd == GPIO_GET_LINEINFO_IOCTL || + cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) { struct gpioline_info lineinfo; - struct gpio_desc *desc; if (copy_from_user(&lineinfo, ip, sizeof(lineinfo))) return -EFAULT; @@ -1245,11 +1259,25 @@ static long gpio_ioctl(struct file *filp, unsigned int cmd, unsigned long arg) if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) return -EFAULT; + + if (cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) + set_bit(desc_to_gpio(desc), priv->watched_lines); + 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); + } else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) { + if (copy_from_user(&offset, ip, sizeof(offset))) + return -EFAULT; + + desc = gpiochip_get_desc(chip, offset); + if (IS_ERR(desc)) + return PTR_ERR(desc); + + clear_bit(desc_to_gpio(desc), &desc->flags); + return 0; } return -EINVAL; } @@ -1262,6 +1290,101 @@ static long gpio_ioctl_compat(struct file *filp, unsigned int cmd, } #endif +static struct gpio_chardev_data * +to_gpio_chardev_data(struct notifier_block *nb) +{ + return container_of(nb, struct gpio_chardev_data, lineinfo_changed_nb); +} + +static int lineinfo_changed_notify(struct notifier_block *nb, + unsigned long action, void *data) +{ + struct gpio_chardev_data *priv = to_gpio_chardev_data(nb); + struct gpioline_info_changed chg; + struct gpio_desc *desc = data; + int ret; + + if (!test_bit(desc_to_gpio(desc), priv->watched_lines)) + return NOTIFY_DONE; + + memset(&chg, 0, sizeof(chg)); + chg.info.line_offset = gpio_chip_hwgpio(desc); + chg.event_type = action; + chg.timestamp = ktime_get_ns(); + gpio_desc_to_lineinfo(desc, &chg.info); + + ret = kfifo_in_spinlocked(&priv->events, &chg, 1, &priv->wait.lock); + if (ret) + wake_up_poll(&priv->wait, EPOLLIN); + else + pr_debug_ratelimited("lineinfo event FIFO is full - event dropped\n"); + + return NOTIFY_OK; +} + +static __poll_t lineinfo_watch_poll(struct file *filep, + struct poll_table_struct *pollt) +{ + struct gpio_chardev_data *priv = filep->private_data; + __poll_t events = 0; + + poll_wait(filep, &priv->wait, pollt); + + if (!kfifo_is_empty_spinlocked_noirqsave(&priv->events, + &priv->wait.lock)) + events = EPOLLIN | EPOLLRDNORM; + + return events; +} + +static ssize_t lineinfo_watch_read(struct file *filep, char __user *buf, + size_t count, loff_t *off) +{ + struct gpio_chardev_data *priv = filep->private_data; + struct gpioline_info_changed event; + ssize_t bytes_read = 0; + int ret; + + if (count < sizeof(event)) + return -EINVAL; + + do { + spin_lock(&priv->wait.lock); + if (kfifo_is_empty(&priv->events)) { + if (bytes_read) { + spin_unlock(&priv->wait.lock); + return bytes_read; + } + + if (filep->f_flags & O_NONBLOCK) { + spin_unlock(&priv->wait.lock); + return -EAGAIN; + } + + ret = wait_event_interruptible_locked(priv->wait, + !kfifo_is_empty(&priv->events)); + if (ret) { + spin_unlock(&priv->wait.lock); + return ret; + } + } + + ret = kfifo_out(&priv->events, &event, 1); + spin_unlock(&priv->wait.lock); + if (ret != 1) { + ret = -EIO; + break; + /* We should never get here. See lineevent_read(). */ + } + + if (copy_to_user(buf + bytes_read, &event, sizeof(event))) + return -EFAULT; + bytes_read += sizeof(event); + } while (count >= bytes_read + sizeof(event)); + + return bytes_read; +} + /** * gpio_chrdev_open() - open the chardev for ioctl operations * @inode: inode for this chardev @@ -1272,14 +1395,48 @@ static int gpio_chrdev_open(struct inode *inode, struct file *filp) { struct gpio_device *gdev = container_of(inode->i_cdev, struct gpio_device, chrdev); + struct gpio_chardev_data *priv; + int ret = -ENOMEM; /* Fail on open if the backing gpiochip is gone */ if (!gdev->chip) return -ENODEV; + + priv = kzalloc(sizeof(*priv), GFP_KERNEL); + if (!priv) + return -ENOMEM; + + priv->watched_lines = bitmap_zalloc(gdev->chip->ngpio, GFP_KERNEL); + if (!priv->watched_lines) + goto out_free_priv; + + init_waitqueue_head(&priv->wait); + INIT_KFIFO(priv->events); + priv->gdev = gdev; + + priv->lineinfo_changed_nb.notifier_call = lineinfo_changed_notify; + ret = atomic_notifier_chain_register(&gdev->notifier, + &priv->lineinfo_changed_nb); + if (ret) + goto out_free_bitmap; + get_device(&gdev->dev); - filp->private_data = gdev; + filp->private_data = priv; - return nonseekable_open(inode, filp); + ret = nonseekable_open(inode, filp); + if (ret) + goto out_unregister_notifier; + + return ret; + +out_unregister_notifier: + atomic_notifier_chain_unregister(&gdev->notifier, + &priv->lineinfo_changed_nb); +out_free_bitmap: + bitmap_free(priv->watched_lines); +out_free_priv: + kfree(priv); + return ret; } /** @@ -1290,17 +1447,23 @@ static int gpio_chrdev_open(struct inode *inode, struct file *filp) */ static int gpio_chrdev_release(struct inode *inode, struct file *filp) { - struct gpio_device *gdev = container_of(inode->i_cdev, - struct gpio_device, chrdev); + struct gpio_chardev_data *priv = filp->private_data; + struct gpio_device *gdev = priv->gdev; + bitmap_free(priv->watched_lines); + atomic_notifier_chain_unregister(&gdev->notifier, + &priv->lineinfo_changed_nb); put_device(&gdev->dev); + kfree(priv); + return 0; } - static const struct file_operations gpio_fileops = { .release = gpio_chrdev_release, .open = gpio_chrdev_open, + .poll = lineinfo_watch_poll, + .read = lineinfo_watch_read, .owner = THIS_MODULE, .llseek = no_llseek, .unlocked_ioctl = gpio_ioctl, @@ -1511,6 +1674,8 @@ int gpiochip_add_data_with_key(struct gpio_chip *chip, void *data, spin_unlock_irqrestore(&gpio_lock, flags); + ATOMIC_INIT_NOTIFIER_HEAD(&gdev->notifier); + #ifdef CONFIG_PINCTRL INIT_LIST_HEAD(&gdev->pin_ranges); #endif @@ -2843,6 +3008,8 @@ static int gpiod_request_commit(struct gpio_desc *desc, const char *label) } done: spin_unlock_irqrestore(&gpio_lock, flags); + atomic_notifier_call_chain(&desc->gdev->notifier, + GPIOLINE_CHANGED_REQUESTED, desc); return ret; } @@ -2940,6 +3107,9 @@ static bool gpiod_free_commit(struct gpio_desc *desc) } spin_unlock_irqrestore(&gpio_lock, flags); + atomic_notifier_call_chain(&desc->gdev->notifier, + GPIOLINE_CHANGED_RELEASED, desc); + return ret; } diff --git a/drivers/gpio/gpiolib.h b/drivers/gpio/gpiolib.h index 3e0aab2945d8..5ab90746b519 100644 --- a/drivers/gpio/gpiolib.h +++ b/drivers/gpio/gpiolib.h @@ -56,6 +56,7 @@ struct gpio_device { const char *label; void *data; struct list_head list; + struct atomic_notifier_head notifier; #ifdef CONFIG_PINCTRL /* diff --git a/include/uapi/linux/gpio.h b/include/uapi/linux/gpio.h index 799cf823d493..dca320764e4d 100644 --- a/include/uapi/linux/gpio.h +++ b/include/uapi/linux/gpio.h @@ -59,6 +59,34 @@ struct gpioline_info { /* Maximum number of requested handles */ #define GPIOHANDLES_MAX 64 +/* Possible line status change events */ +enum { + GPIOLINE_CHANGED_REQUESTED = 1, + GPIOLINE_CHANGED_RELEASED, + GPIOLINE_CHANGED_CONFIG, +}; + +/** + * struct gpioline_info_changed - Information about a change in status + * of a GPIO line + * @info: updated line information + * @timestamp: estimate of time of status change occurrence, in nanoseconds + * and GPIOLINE_CHANGED_CONFIG + * @event_type: one of GPIOLINE_CHANGED_REQUESTED, GPIOLINE_CHANGED_RELEASED + * + * Note: struct gpioline_info embedded here has 32-bit alignment on its own, + * but it works fine with 64-bit alignment too. With its 72 byte size, we can + * guarantee there are no implicit holes between it and subsequent members. + * The 20-byte padding at the end makes sure we don't add any implicit padding + * at the end of the structure on 64-bit architectures. + */ +struct gpioline_info_changed { + struct gpioline_info info; + __u64 timestamp; + __u32 event_type; + __u32 padding[5]; /* for future use */ +}; + /* Linerequest flags */ #define GPIOHANDLE_REQUEST_INPUT (1UL << 0) #define GPIOHANDLE_REQUEST_OUTPUT (1UL << 1) @@ -176,6 +204,8 @@ struct gpioevent_data { #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_LINEINFO_WATCH_IOCTL _IOWR(0xB4, 0x0b, struct gpioline_info) +#define GPIO_GET_LINEINFO_UNWATCH_IOCTL _IOWR(0xB4, 0x0c, __u32) #define GPIO_GET_LINEHANDLE_IOCTL _IOWR(0xB4, 0x03, struct gpiohandle_request) #define GPIO_GET_LINEEVENT_IOCTL _IOWR(0xB4, 0x04, struct gpioevent_request) |