diff options
Diffstat (limited to 'drivers/gpio/gpiolib-cdev.c')
| -rw-r--r-- | drivers/gpio/gpiolib-cdev.c | 1121 |
1 files changed, 1121 insertions, 0 deletions
diff --git a/drivers/gpio/gpiolib-cdev.c b/drivers/gpio/gpiolib-cdev.c new file mode 100644 index 000000000000..e6c9b78adfc2 --- /dev/null +++ b/drivers/gpio/gpiolib-cdev.c @@ -0,0 +1,1121 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include <linux/anon_inodes.h> +#include <linux/bitmap.h> +#include <linux/cdev.h> +#include <linux/compat.h> +#include <linux/device.h> +#include <linux/err.h> +#include <linux/file.h> +#include <linux/gpio.h> +#include <linux/gpio/driver.h> +#include <linux/interrupt.h> +#include <linux/irqreturn.h> +#include <linux/kernel.h> +#include <linux/kfifo.h> +#include <linux/module.h> +#include <linux/pinctrl/consumer.h> +#include <linux/poll.h> +#include <linux/spinlock.h> +#include <linux/timekeeping.h> +#include <linux/uaccess.h> +#include <uapi/linux/gpio.h> + +#include "gpiolib.h" +#include "gpiolib-cdev.h" + +/* Character device interface to GPIO. + * + * The GPIO character device, /dev/gpiochipN, provides userspace an + * interface to gpiolib GPIOs via ioctl()s. + */ + +/* + * GPIO line handle management + */ + +/** + * struct linehandle_state - contains the state of a userspace handle + * @gdev: the GPIO device the handle pertains to + * @label: consumer label used to tag descriptors + * @descs: the GPIO descriptors held by this handle + * @num_descs: the number of descriptors held in the descs array + */ +struct linehandle_state { + struct gpio_device *gdev; + const char *label; + struct gpio_desc *descs[GPIOHANDLES_MAX]; + u32 num_descs; +}; + +#define GPIOHANDLE_REQUEST_VALID_FLAGS \ + (GPIOHANDLE_REQUEST_INPUT | \ + GPIOHANDLE_REQUEST_OUTPUT | \ + GPIOHANDLE_REQUEST_ACTIVE_LOW | \ + GPIOHANDLE_REQUEST_BIAS_PULL_UP | \ + GPIOHANDLE_REQUEST_BIAS_PULL_DOWN | \ + GPIOHANDLE_REQUEST_BIAS_DISABLE | \ + GPIOHANDLE_REQUEST_OPEN_DRAIN | \ + GPIOHANDLE_REQUEST_OPEN_SOURCE) + +static int linehandle_validate_flags(u32 flags) +{ + /* Return an error if an unknown flag is set */ + if (flags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) + return -EINVAL; + + /* + * Do not allow both INPUT & OUTPUT flags to be set as they are + * contradictory. + */ + if ((flags & GPIOHANDLE_REQUEST_INPUT) && + (flags & GPIOHANDLE_REQUEST_OUTPUT)) + return -EINVAL; + + /* + * Do not allow OPEN_SOURCE & OPEN_DRAIN flags in a single request. If + * the hardware actually supports enabling both at the same time the + * electrical result would be disastrous. + */ + if ((flags & GPIOHANDLE_REQUEST_OPEN_DRAIN) && + (flags & GPIOHANDLE_REQUEST_OPEN_SOURCE)) + return -EINVAL; + + /* OPEN_DRAIN and OPEN_SOURCE flags only make sense for output mode. */ + if (!(flags & GPIOHANDLE_REQUEST_OUTPUT) && + ((flags & GPIOHANDLE_REQUEST_OPEN_DRAIN) || + (flags & GPIOHANDLE_REQUEST_OPEN_SOURCE))) + return -EINVAL; + + /* Bias flags only allowed for input or output mode. */ + if (!((flags & GPIOHANDLE_REQUEST_INPUT) || + (flags & GPIOHANDLE_REQUEST_OUTPUT)) && + ((flags & GPIOHANDLE_REQUEST_BIAS_DISABLE) || + (flags & GPIOHANDLE_REQUEST_BIAS_PULL_UP) || + (flags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN))) + return -EINVAL; + + /* Only one bias flag can be set. */ + if (((flags & GPIOHANDLE_REQUEST_BIAS_DISABLE) && + (flags & (GPIOHANDLE_REQUEST_BIAS_PULL_DOWN | + GPIOHANDLE_REQUEST_BIAS_PULL_UP))) || + ((flags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN) && + (flags & GPIOHANDLE_REQUEST_BIAS_PULL_UP))) + return -EINVAL; + + return 0; +} + +static void linehandle_flags_to_desc_flags(u32 lflags, unsigned long *flagsp) +{ + assign_bit(FLAG_ACTIVE_LOW, flagsp, + lflags & GPIOHANDLE_REQUEST_ACTIVE_LOW); + assign_bit(FLAG_OPEN_DRAIN, flagsp, + lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN); + assign_bit(FLAG_OPEN_SOURCE, flagsp, + lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE); + assign_bit(FLAG_PULL_UP, flagsp, + lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP); + assign_bit(FLAG_PULL_DOWN, flagsp, + lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN); + assign_bit(FLAG_BIAS_DISABLE, flagsp, + lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE); +} + +static long linehandle_set_config(struct linehandle_state *lh, + void __user *ip) +{ + struct gpiohandle_config gcnf; + struct gpio_desc *desc; + int i, ret; + u32 lflags; + + if (copy_from_user(&gcnf, ip, sizeof(gcnf))) + return -EFAULT; + + lflags = gcnf.flags; + ret = linehandle_validate_flags(lflags); + if (ret) + return ret; + + for (i = 0; i < lh->num_descs; i++) { + desc = lh->descs[i]; + linehandle_flags_to_desc_flags(gcnf.flags, &desc->flags); + + /* + * Lines have to be requested explicitly for input + * or output, else the line will be treated "as is". + */ + if (lflags & GPIOHANDLE_REQUEST_OUTPUT) { + int val = !!gcnf.default_values[i]; + + ret = gpiod_direction_output(desc, val); + if (ret) + return ret; + } else if (lflags & GPIOHANDLE_REQUEST_INPUT) { + ret = gpiod_direction_input(desc); + if (ret) + return ret; + } + + blocking_notifier_call_chain(&desc->gdev->notifier, + GPIOLINE_CHANGED_CONFIG, desc); + } + return 0; +} + +static long linehandle_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + struct linehandle_state *lh = file->private_data; + void __user *ip = (void __user *)arg; + struct gpiohandle_data ghd; + DECLARE_BITMAP(vals, GPIOHANDLES_MAX); + int i; + + if (cmd == GPIOHANDLE_GET_LINE_VALUES_IOCTL) { + /* NOTE: It's ok to read values of output lines. */ + int ret = gpiod_get_array_value_complex(false, + true, + lh->num_descs, + lh->descs, + NULL, + vals); + if (ret) + return ret; + + memset(&ghd, 0, sizeof(ghd)); + for (i = 0; i < lh->num_descs; i++) + ghd.values[i] = test_bit(i, vals); + + if (copy_to_user(ip, &ghd, sizeof(ghd))) + return -EFAULT; + + return 0; + } else if (cmd == GPIOHANDLE_SET_LINE_VALUES_IOCTL) { + /* + * All line descriptors were created at once with the same + * flags so just check if the first one is really output. + */ + if (!test_bit(FLAG_IS_OUT, &lh->descs[0]->flags)) + return -EPERM; + + if (copy_from_user(&ghd, ip, sizeof(ghd))) + return -EFAULT; + + /* Clamp all values to [0,1] */ + for (i = 0; i < lh->num_descs; i++) + __assign_bit(i, vals, ghd.values[i]); + + /* Reuse the array setting function */ + return gpiod_set_array_value_complex(false, + true, + lh->num_descs, + lh->descs, + NULL, + vals); + } else if (cmd == GPIOHANDLE_SET_CONFIG_IOCTL) { + return linehandle_set_config(lh, ip); + } + return -EINVAL; +} + +#ifdef CONFIG_COMPAT +static long linehandle_ioctl_compat(struct file *file, unsigned int cmd, + unsigned long arg) +{ + return linehandle_ioctl(file, cmd, (unsigned long)compat_ptr(arg)); +} +#endif + +static void linehandle_free(struct linehandle_state *lh) +{ + int i; + + for (i = 0; i < lh->num_descs; i++) + if (lh->descs[i]) + gpiod_free(lh->descs[i]); + kfree(lh->label); + put_device(&lh->gdev->dev); + kfree(lh); +} + +static int linehandle_release(struct inode *inode, struct file *file) +{ + linehandle_free(file->private_data); + return 0; +} + +static const struct file_operations linehandle_fileops = { + .release = linehandle_release, + .owner = THIS_MODULE, + .llseek = noop_llseek, + .unlocked_ioctl = linehandle_ioctl, +#ifdef CONFIG_COMPAT + .compat_ioctl = linehandle_ioctl_compat, +#endif +}; + +static int linehandle_create(struct gpio_device *gdev, void __user *ip) +{ + struct gpiohandle_request handlereq; + struct linehandle_state *lh; + struct file *file; + int fd, i, ret; + u32 lflags; + + if (copy_from_user(&handlereq, ip, sizeof(handlereq))) + return -EFAULT; + if ((handlereq.lines == 0) || (handlereq.lines > GPIOHANDLES_MAX)) + return -EINVAL; + + lflags = handlereq.flags; + + ret = linehandle_validate_flags(lflags); + if (ret) + return ret; + + lh = kzalloc(sizeof(*lh), GFP_KERNEL); + if (!lh) + return -ENOMEM; + lh->gdev = gdev; + get_device(&gdev->dev); + + /* Make sure this is terminated */ + handlereq.consumer_label[sizeof(handlereq.consumer_label)-1] = '\0'; + if (strlen(handlereq.consumer_label)) { + lh->label = kstrdup(handlereq.consumer_label, + GFP_KERNEL); + if (!lh->label) { + ret = -ENOMEM; + goto out_free_lh; + } + } + + lh->num_descs = handlereq.lines; + + /* Request each GPIO */ + for (i = 0; i < handlereq.lines; i++) { + u32 offset = handlereq.lineoffsets[i]; + struct gpio_desc *desc = gpiochip_get_desc(gdev->chip, offset); + + if (IS_ERR(desc)) { + ret = PTR_ERR(desc); + goto out_free_lh; + } + + ret = gpiod_request(desc, lh->label); + if (ret) + goto out_free_lh; + lh->descs[i] = desc; + linehandle_flags_to_desc_flags(handlereq.flags, &desc->flags); + + ret = gpiod_set_transitory(desc, false); + if (ret < 0) + goto out_free_lh; + + /* + * Lines have to be requested explicitly for input + * or output, else the line will be treated "as is". + */ + if (lflags & GPIOHANDLE_REQUEST_OUTPUT) { + int val = !!handlereq.default_values[i]; + + ret = gpiod_direction_output(desc, val); + if (ret) + goto out_free_lh; + } else if (lflags & GPIOHANDLE_REQUEST_INPUT) { + ret = gpiod_direction_input(desc); + if (ret) + goto out_free_lh; + } + + blocking_notifier_call_chain(&desc->gdev->notifier, + GPIOLINE_CHANGED_REQUESTED, desc); + + dev_dbg(&gdev->dev, "registered chardev handle for line %d\n", + offset); + } + + fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC); + if (fd < 0) { + ret = fd; + goto out_free_lh; + } + + file = anon_inode_getfile("gpio-linehandle", + &linehandle_fileops, + lh, + O_RDONLY | O_CLOEXEC); + if (IS_ERR(file)) { + ret = PTR_ERR(file); + goto out_put_unused_fd; + } + + handlereq.fd = fd; + if (copy_to_user(ip, &handlereq, sizeof(handlereq))) { + /* + * fput() will trigger the release() callback, so do not go onto + * the regular error cleanup path here. + */ + fput(file); + put_unused_fd(fd); + return -EFAULT; + } + + fd_install(fd, file); + + dev_dbg(&gdev->dev, "registered chardev handle for %d lines\n", + lh->num_descs); + + return 0; + +out_put_unused_fd: + put_unused_fd(fd); +out_free_lh: + linehandle_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 + * @timestamp: cache for the timestamp storing it between hardirq + * and IRQ thread, used to bring the timestamp close to the actual + * event + */ +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); + u64 timestamp; +}; + +#define GPIOEVENT_REQUEST_VALID_FLAGS \ + (GPIOEVENT_REQUEST_RISING_EDGE | \ + GPIOEVENT_REQUEST_FALLING_EDGE) + +static __poll_t lineevent_poll(struct file *file, + struct poll_table_struct *wait) +{ + struct lineevent_state *le = file->private_data; + __poll_t events = 0; + + poll_wait(file, &le->wait, wait); + + if (!kfifo_is_empty_spinlocked_noirqsave(&le->events, &le->wait.lock)) + events = EPOLLIN | EPOLLRDNORM; + + return events; +} + + +static ssize_t lineevent_read(struct file *file, + char __user *buf, + size_t count, + loff_t *f_ps) +{ + struct lineevent_state *le = file->private_data; + struct gpioevent_data ge; + ssize_t bytes_read = 0; + int ret; + + if (count < sizeof(ge)) + return -EINVAL; + + do { + spin_lock(&le->wait.lock); + if (kfifo_is_empty(&le->events)) { + if (bytes_read) { + spin_unlock(&le->wait.lock); + return bytes_read; + } + + if (file->f_flags & O_NONBLOCK) { + spin_unlock(&le->wait.lock); + return -EAGAIN; + } + + ret = wait_event_interruptible_locked(le->wait, + !kfifo_is_empty(&le->events)); + if (ret) { + spin_unlock(&le->wait.lock); + return ret; + } + } + + ret = kfifo_out(&le->events, &ge, 1); + spin_unlock(&le->wait.lock); + if (ret != 1) { + /* + * This should never happen - we were holding the lock + * from the moment we learned the fifo is no longer + * empty until now. + */ + ret = -EIO; + break; + } + + if (copy_to_user(buf + bytes_read, &ge, sizeof(ge))) + return -EFAULT; + bytes_read += sizeof(ge); + } while (count >= bytes_read + sizeof(ge)); + + return bytes_read; +} + +static void lineevent_free(struct lineevent_state *le) +{ + if (le->irq) + free_irq(le->irq, le); + if (le->desc) + gpiod_free(le->desc); + kfree(le->label); + put_device(&le->gdev->dev); + kfree(le); +} + +static int lineevent_release(struct inode *inode, struct file *file) +{ + lineevent_free(file->private_data); + return 0; +} + +static long lineevent_ioctl(struct file *file, unsigned int cmd, + unsigned long arg) +{ + struct lineevent_state *le = file->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; + + memset(&ghd, 0, sizeof(ghd)); + + 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 *file, unsigned int cmd, + unsigned long arg) +{ + return lineevent_ioctl(file, 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 +}; + +static irqreturn_t lineevent_irq_thread(int irq, void *p) +{ + struct lineevent_state *le = p; + struct gpioevent_data ge; + int ret; + + /* Do not leak kernel stack to userspace */ + memset(&ge, 0, sizeof(ge)); + + /* + * We may be running from a nested threaded interrupt in which case + * we didn't get the timestamp from lineevent_irq_handler(). + */ + if (!le->timestamp) + ge.timestamp = ktime_get_ns(); + else + ge.timestamp = le->timestamp; + + if (le->eflags & GPIOEVENT_REQUEST_RISING_EDGE + && le->eflags & GPIOEVENT_REQUEST_FALLING_EDGE) { + 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; + } else { + return IRQ_NONE; + } + + ret = kfifo_in_spinlocked_noirqsave(&le->events, &ge, + 1, &le->wait.lock); + if (ret) + wake_up_poll(&le->wait, EPOLLIN); + else + pr_debug_ratelimited("event FIFO is full - event dropped\n"); + + return IRQ_HANDLED; +} + +static irqreturn_t lineevent_irq_handler(int irq, void *p) +{ + struct lineevent_state *le = p; + + /* + * Just store the timestamp in hardirq context so we get it as + * close in time as possible to the actual event. + */ + le->timestamp = ktime_get_ns(); + + return IRQ_WAKE_THREAD; +} + +static int lineevent_create(struct gpio_device *gdev, void __user *ip) +{ + struct gpioevent_request eventreq; + struct lineevent_state *le; + struct gpio_desc *desc; + struct file *file; + u32 offset; + u32 lflags; + u32 eflags; + int fd; + int ret; + int irq, irqflags = 0; + + if (copy_from_user(&eventreq, ip, sizeof(eventreq))) + return -EFAULT; + + offset = eventreq.lineoffset; + lflags = eventreq.handleflags; + eflags = eventreq.eventflags; + + desc = gpiochip_get_desc(gdev->chip, offset); + if (IS_ERR(desc)) + return PTR_ERR(desc); + + /* Return an error if a unknown flag is set */ + if ((lflags & ~GPIOHANDLE_REQUEST_VALID_FLAGS) || + (eflags & ~GPIOEVENT_REQUEST_VALID_FLAGS)) + return -EINVAL; + + /* This is just wrong: we don't look for events on output lines */ + if ((lflags & GPIOHANDLE_REQUEST_OUTPUT) || + (lflags & GPIOHANDLE_REQUEST_OPEN_DRAIN) || + (lflags & GPIOHANDLE_REQUEST_OPEN_SOURCE)) + return -EINVAL; + + /* Only one bias flag can be set. */ + if (((lflags & GPIOHANDLE_REQUEST_BIAS_DISABLE) && + (lflags & (GPIOHANDLE_REQUEST_BIAS_PULL_DOWN | + GPIOHANDLE_REQUEST_BIAS_PULL_UP))) || + ((lflags & GPIOHANDLE_REQUEST_BIAS_PULL_DOWN) && + (lflags & GPIOHANDLE_REQUEST_BIAS_PULL_UP))) + return -EINVAL; + + 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; + } + } + + ret = gpiod_request(desc, le->label); + if (ret) + goto out_free_le; + le->desc = desc; + le->eflags = eflags; + + linehandle_flags_to_desc_flags(lflags, &desc->flags); + + ret = gpiod_direction_input(desc); + if (ret) + goto out_free_le; + + blocking_notifier_call_chain(&desc->gdev->notifier, + GPIOLINE_CHANGED_REQUESTED, desc); + + irq = gpiod_to_irq(desc); + if (irq <= 0) { + ret = -ENODEV; + goto out_free_le; + } + le->irq = irq; + + if (eflags & GPIOEVENT_REQUEST_RISING_EDGE) + irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ? + IRQF_TRIGGER_FALLING : IRQF_TRIGGER_RISING; + if (eflags & GPIOEVENT_REQUEST_FALLING_EDGE) + irqflags |= test_bit(FLAG_ACTIVE_LOW, &desc->flags) ? + IRQF_TRIGGER_RISING : IRQF_TRIGGER_FALLING; + irqflags |= IRQF_ONESHOT; + + INIT_KFIFO(le->events); + init_waitqueue_head(&le->wait); + + /* Request a thread to read the events */ + ret = request_threaded_irq(le->irq, + lineevent_irq_handler, + lineevent_irq_thread, + irqflags, + le->label, + le); + if (ret) + goto out_free_le; + + fd = get_unused_fd_flags(O_RDONLY | O_CLOEXEC); + if (fd < 0) { + ret = fd; + goto out_free_le; + } + + file = anon_inode_getfile("gpio-event", + &lineevent_fileops, + le, + O_RDONLY | O_CLOEXEC); + if (IS_ERR(file)) { + ret = PTR_ERR(file); + goto out_put_unused_fd; + } + + eventreq.fd = fd; + if (copy_to_user(ip, &eventreq, sizeof(eventreq))) { + /* + * fput() will trigger the release() callback, so do not go onto + * the regular error cleanup path here. + */ + fput(file); + put_unused_fd(fd); + return -EFAULT; + } + + fd_install(fd, file); + + return 0; + +out_put_unused_fd: + put_unused_fd(fd); +out_free_le: + lineevent_free(le); + return ret; +} + +static void gpio_desc_to_lineinfo(struct gpio_desc *desc, + struct gpioline_info *info) +{ + struct gpio_chip *gc = desc->gdev->chip; + bool ok_for_pinctrl; + unsigned long flags; + + /* + * This function takes a mutex so we must check this before taking + * the spinlock. + * + * FIXME: find a non-racy way to retrieve this information. Maybe a + * lock common to both frameworks? + */ + ok_for_pinctrl = + pinctrl_gpio_can_use_line(gc->base + info->line_offset); + + spin_lock_irqsave(&gpio_lock, flags); + + if (desc->name) { + strncpy(info->name, desc->name, sizeof(info->name)); + info->name[sizeof(info->name) - 1] = '\0'; + } else { + info->name[0] = '\0'; + } + + if (desc->label) { + strncpy(info->consumer, desc->label, sizeof(info->consumer)); + info->consumer[sizeof(info->consumer) - 1] = '\0'; + } else { + info->consumer[0] = '\0'; + } + + /* + * Userspace only need to know that the kernel is using this GPIO so + * it can't use it. + */ + info->flags = 0; + if (test_bit(FLAG_REQUESTED, &desc->flags) || + test_bit(FLAG_IS_HOGGED, &desc->flags) || + test_bit(FLAG_USED_AS_IRQ, &desc->flags) || + test_bit(FLAG_EXPORT, &desc->flags) || + test_bit(FLAG_SYSFS, &desc->flags) || + !ok_for_pinctrl) + info->flags |= GPIOLINE_FLAG_KERNEL; + if (test_bit(FLAG_IS_OUT, &desc->flags)) + info->flags |= GPIOLINE_FLAG_IS_OUT; + if (test_bit(FLAG_ACTIVE_LOW, &desc->flags)) + info->flags |= GPIOLINE_FLAG_ACTIVE_LOW; + if (test_bit(FLAG_OPEN_DRAIN, &desc->flags)) + info->flags |= (GPIOLINE_FLAG_OPEN_DRAIN | + GPIOLINE_FLAG_IS_OUT); + if (test_bit(FLAG_OPEN_SOURCE, &desc->flags)) + info->flags |= (GPIOLINE_FLAG_OPEN_SOURCE | + GPIOLINE_FLAG_IS_OUT); + if (test_bit(FLAG_BIAS_DISABLE, &desc->flags)) + info->flags |= GPIOLINE_FLAG_BIAS_DISABLE; + if (test_bit(FLAG_PULL_DOWN, &desc->flags)) + info->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN; + if (test_bit(FLAG_PULL_UP, &desc->flags)) + info->flags |= GPIOLINE_FLAG_BIAS_PULL_UP; + + 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 *file, unsigned int cmd, unsigned long arg) +{ + struct gpio_chardev_data *cdev = file->private_data; + struct gpio_device *gdev = cdev->gdev; + struct gpio_chip *gc = 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 (!gc) + return -ENODEV; + + /* Fill in the struct and pass to userspace */ + if (cmd == GPIO_GET_CHIPINFO_IOCTL) { + struct gpiochip_info chipinfo; + + memset(&chipinfo, 0, sizeof(chipinfo)); + + strncpy(chipinfo.name, dev_name(&gdev->dev), + sizeof(chipinfo.name)); + chipinfo.name[sizeof(chipinfo.name)-1] = '\0'; + strncpy(chipinfo.label, gdev->label, + sizeof(chipinfo.label)); + chipinfo.label[sizeof(chipinfo.label)-1] = '\0'; + chipinfo.lines = gdev->ngpio; + if (copy_to_user(ip, &chipinfo, sizeof(chipinfo))) + return -EFAULT; + return 0; + } else if (cmd == GPIO_GET_LINEINFO_IOCTL) { + struct gpioline_info lineinfo; + + if (copy_from_user(&lineinfo, ip, sizeof(lineinfo))) + return -EFAULT; + + /* this doubles as a range check on line_offset */ + desc = gpiochip_get_desc(gc, lineinfo.line_offset); + if (IS_ERR(desc)) + return PTR_ERR(desc); + + gpio_desc_to_lineinfo(desc, &lineinfo); + + if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) + return -EFAULT; + 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_WATCH_IOCTL) { + struct gpioline_info lineinfo; + + if (copy_from_user(&lineinfo, ip, sizeof(lineinfo))) + return -EFAULT; + + /* this doubles as a range check on line_offset */ + desc = gpiochip_get_desc(gc, lineinfo.line_offset); + if (IS_ERR(desc)) + return PTR_ERR(desc); + + if (test_and_set_bit(lineinfo.line_offset, cdev->watched_lines)) + return -EBUSY; + + gpio_desc_to_lineinfo(desc, &lineinfo); + + if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) { + clear_bit(lineinfo.line_offset, cdev->watched_lines); + return -EFAULT; + } + + return 0; + } else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) { + if (copy_from_user(&offset, ip, sizeof(offset))) + return -EFAULT; + + if (offset >= cdev->gdev->ngpio) + return -EINVAL; + + if (!test_and_clear_bit(offset, cdev->watched_lines)) + return -EBUSY; + + return 0; + } + return -EINVAL; +} + +#ifdef CONFIG_COMPAT +static long gpio_ioctl_compat(struct file *file, unsigned int cmd, + unsigned long arg) +{ + return gpio_ioctl(file, cmd, (unsigned long)compat_ptr(arg)); +} +#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 *cdev = to_gpio_chardev_data(nb); + struct gpioline_info_changed chg; + struct gpio_desc *desc = data; + int ret; + + if (!test_bit(gpio_chip_hwgpio(desc), cdev->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(&cdev->events, &chg, 1, &cdev->wait.lock); + if (ret) + wake_up_poll(&cdev->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 *file, + struct poll_table_struct *pollt) +{ + struct gpio_chardev_data *cdev = file->private_data; + __poll_t events = 0; + + poll_wait(file, &cdev->wait, pollt); + + if (!kfifo_is_empty_spinlocked_noirqsave(&cdev->events, + &cdev->wait.lock)) + events = EPOLLIN | EPOLLRDNORM; + + return events; +} + +static ssize_t lineinfo_watch_read(struct file *file, char __user *buf, + size_t count, loff_t *off) +{ + struct gpio_chardev_data *cdev = file->private_data; + struct gpioline_info_changed event; + ssize_t bytes_read = 0; + int ret; + + if (count < sizeof(event)) + return -EINVAL; + + do { + spin_lock(&cdev->wait.lock); + if (kfifo_is_empty(&cdev->events)) { + if (bytes_read) { + spin_unlock(&cdev->wait.lock); + return bytes_read; + } + + if (file->f_flags & O_NONBLOCK) { + spin_unlock(&cdev->wait.lock); + return -EAGAIN; + } + + ret = wait_event_interruptible_locked(cdev->wait, + !kfifo_is_empty(&cdev->events)); + if (ret) { + spin_unlock(&cdev->wait.lock); + return ret; + } + } + + ret = kfifo_out(&cdev->events, &event, 1); + spin_unlock(&cdev->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 + * @file: file struct for storing private data + * Returns 0 on success + */ +static int gpio_chrdev_open(struct inode *inode, struct file *file) +{ + struct gpio_device *gdev = container_of(inode->i_cdev, + struct gpio_device, chrdev); + struct gpio_chardev_data *cdev; + int ret = -ENOMEM; + + /* Fail on open if the backing gpiochip is gone */ + if (!gdev->chip) + return -ENODEV; + + cdev = kzalloc(sizeof(*cdev), GFP_KERNEL); + if (!cdev) + return -ENOMEM; + + cdev->watched_lines = bitmap_zalloc(gdev->chip->ngpio, GFP_KERNEL); + if (!cdev->watched_lines) + goto out_free_cdev; + + init_waitqueue_head(&cdev->wait); + INIT_KFIFO(cdev->events); + cdev->gdev = gdev; + + cdev->lineinfo_changed_nb.notifier_call = lineinfo_changed_notify; + ret = blocking_notifier_chain_register(&gdev->notifier, + &cdev->lineinfo_changed_nb); + if (ret) + goto out_free_bitmap; + + get_device(&gdev->dev); + file->private_data = cdev; + + ret = nonseekable_open(inode, file); + if (ret) + goto out_unregister_notifier; + + return ret; + +out_unregister_notifier: + blocking_notifier_chain_unregister(&gdev->notifier, + &cdev->lineinfo_changed_nb); +out_free_bitmap: + bitmap_free(cdev->watched_lines); +out_free_cdev: + kfree(cdev); + return ret; +} + +/** + * gpio_chrdev_release() - close chardev after ioctl operations + * @inode: inode for this chardev + * @file: file struct for storing private data + * Returns 0 on success + */ +static int gpio_chrdev_release(struct inode *inode, struct file *file) +{ + struct gpio_chardev_data *cdev = file->private_data; + struct gpio_device *gdev = cdev->gdev; + + bitmap_free(cdev->watched_lines); + blocking_notifier_chain_unregister(&gdev->notifier, + &cdev->lineinfo_changed_nb); + put_device(&gdev->dev); + kfree(cdev); + + 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, +#ifdef CONFIG_COMPAT + .compat_ioctl = gpio_ioctl_compat, +#endif +}; + +int gpiolib_cdev_register(struct gpio_device *gdev, dev_t devt) +{ + int ret; + + cdev_init(&gdev->chrdev, &gpio_fileops); + gdev->chrdev.owner = THIS_MODULE; + gdev->dev.devt = MKDEV(MAJOR(devt), gdev->id); + + ret = cdev_device_add(&gdev->chrdev, &gdev->dev); + if (ret) + return ret; + + chip_dbg(gdev->chip, "added GPIO chardev (%d:%d)\n", + MAJOR(devt), gdev->id); + + return 0; +} + +void gpiolib_cdev_unregister(struct gpio_device *gdev) +{ + cdev_device_del(&gdev->chrdev, &gdev->dev); +} |