linux/drivers/gpio/gpiolib-cdev.c

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// 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);
}