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gpiolib: cdev: support GPIO_V2_GET_LINEINFO_IOCTL and GPIO_V2_GET_LIN…
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…EINFO_WATCH_IOCTL

Add support for GPIO_V2_GET_LINEINFO_IOCTL and
GPIO_V2_GET_LINEINFO_WATCH_IOCTL.

The core of this change is the event kfifo switching to contain
struct gpioline_info_changed_v2, instead of v1 as v2 is richer.

The two uAPI versions are mostly independent - other than where they both
provide line info changes via reads on the chip fd.  As the info change
structs differ between v1 and v2, the infowatch implementation tracks which
version of the infowatch ioctl, either GPIO_GET_LINEINFO_WATCH_IOCTL or
GPIO_V2_GET_LINEINFO_WATCH_IOCTL, initiates the initial watch and returns
the corresponding info change struct to the read.  The version supported
on that fd locks to that version on the first watch request, so subsequent
watches from that process must use the same uAPI version.

Signed-off-by: Kent Gibson <warthog618@gmail.com>
Signed-off-by: Bartosz Golaszewski <bgolaszewski@baylibre.com>
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@warthog618 @brgl
warthog618 authored and brgl committed Sep 30, 2020
1 parent 3c0d9c6 commit aad9558
Showing 1 changed file with 168 additions and 28 deletions.
196 changes: 168 additions & 28 deletions drivers/gpio/gpiolib-cdev.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -181,7 +181,8 @@ static long linehandle_set_config(struct linehandle_state *lh,
}

blocking_notifier_call_chain(&desc->gdev->notifier,
GPIOLINE_CHANGED_CONFIG, desc);
GPIO_V2_LINE_CHANGED_CONFIG,
desc);
}
return 0;
}
Expand Down Expand Up @@ -353,7 +354,7 @@ static int linehandle_create(struct gpio_device *gdev, void __user *ip)
}

blocking_notifier_call_chain(&desc->gdev->notifier,
GPIOLINE_CHANGED_REQUESTED, desc);
GPIO_V2_LINE_CHANGED_REQUESTED, desc);

dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
offset);
Expand Down Expand Up @@ -749,7 +750,7 @@ static int linereq_create(struct gpio_device *gdev, void __user *ip)
}

blocking_notifier_call_chain(&desc->gdev->notifier,
GPIOLINE_CHANGED_REQUESTED, desc);
GPIO_V2_LINE_CHANGED_REQUESTED, desc);

dev_dbg(&gdev->dev, "registered chardev handle for line %d\n",
offset);
Expand Down Expand Up @@ -1096,7 +1097,7 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
goto out_free_le;

blocking_notifier_call_chain(&desc->gdev->notifier,
GPIOLINE_CHANGED_REQUESTED, desc);
GPIO_V2_LINE_CHANGED_REQUESTED, desc);

irq = gpiod_to_irq(desc);
if (irq <= 0) {
Expand Down Expand Up @@ -1163,17 +1164,58 @@ static int lineevent_create(struct gpio_device *gdev, void __user *ip)
return ret;
}

static void gpio_v2_line_info_to_v1(struct gpio_v2_line_info *info_v2,
struct gpioline_info *info_v1)
{
u64 flagsv2 = info_v2->flags;

memcpy(info_v1->name, info_v2->name, sizeof(info_v1->name));
memcpy(info_v1->consumer, info_v2->consumer, sizeof(info_v1->consumer));
info_v1->line_offset = info_v2->offset;
info_v1->flags = 0;

if (flagsv2 & GPIO_V2_LINE_FLAG_USED)
info_v1->flags |= GPIOLINE_FLAG_KERNEL;

if (flagsv2 & GPIO_V2_LINE_FLAG_OUTPUT)
info_v1->flags |= GPIOLINE_FLAG_IS_OUT;

if (flagsv2 & GPIO_V2_LINE_FLAG_ACTIVE_LOW)
info_v1->flags |= GPIOLINE_FLAG_ACTIVE_LOW;

if (flagsv2 & GPIO_V2_LINE_FLAG_OPEN_DRAIN)
info_v1->flags |= GPIOLINE_FLAG_OPEN_DRAIN;
if (flagsv2 & GPIO_V2_LINE_FLAG_OPEN_SOURCE)
info_v1->flags |= GPIOLINE_FLAG_OPEN_SOURCE;

if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_PULL_UP)
info_v1->flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN)
info_v1->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
if (flagsv2 & GPIO_V2_LINE_FLAG_BIAS_DISABLED)
info_v1->flags |= GPIOLINE_FLAG_BIAS_DISABLE;
}

static void gpio_v2_line_info_changed_to_v1(
struct gpio_v2_line_info_changed *lic_v2,
struct gpioline_info_changed *lic_v1)
{
gpio_v2_line_info_to_v1(&lic_v2->info, &lic_v1->info);
lic_v1->timestamp = lic_v2->timestamp_ns;
lic_v1->event_type = lic_v2->event_type;
}

#endif /* CONFIG_GPIO_CDEV_V1 */

static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
struct gpioline_info *info)
struct gpio_v2_line_info *info)
{
struct gpio_chip *gc = desc->gdev->chip;
bool ok_for_pinctrl;
unsigned long flags;

memset(info, 0, sizeof(*info));
info->line_offset = gpio_chip_hwgpio(desc);
info->offset = gpio_chip_hwgpio(desc);

/*
* This function takes a mutex so we must check this before taking
Expand All @@ -1183,7 +1225,7 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
* lock common to both frameworks?
*/
ok_for_pinctrl =
pinctrl_gpio_can_use_line(gc->base + info->line_offset);
pinctrl_gpio_can_use_line(gc->base + info->offset);

spin_lock_irqsave(&gpio_lock, flags);

Expand All @@ -1204,35 +1246,93 @@ static void gpio_desc_to_lineinfo(struct gpio_desc *desc,
test_bit(FLAG_EXPORT, &desc->flags) ||
test_bit(FLAG_SYSFS, &desc->flags) ||
!ok_for_pinctrl)
info->flags |= GPIOLINE_FLAG_KERNEL;
info->flags |= GPIO_V2_LINE_FLAG_USED;

if (test_bit(FLAG_IS_OUT, &desc->flags))
info->flags |= GPIOLINE_FLAG_IS_OUT;
info->flags |= GPIO_V2_LINE_FLAG_OUTPUT;
else
info->flags |= GPIO_V2_LINE_FLAG_INPUT;

if (test_bit(FLAG_ACTIVE_LOW, &desc->flags))
info->flags |= GPIOLINE_FLAG_ACTIVE_LOW;
info->flags |= GPIO_V2_LINE_FLAG_ACTIVE_LOW;

if (test_bit(FLAG_OPEN_DRAIN, &desc->flags))
info->flags |= (GPIOLINE_FLAG_OPEN_DRAIN |
GPIOLINE_FLAG_IS_OUT);
info->flags |= GPIO_V2_LINE_FLAG_OPEN_DRAIN;
if (test_bit(FLAG_OPEN_SOURCE, &desc->flags))
info->flags |= (GPIOLINE_FLAG_OPEN_SOURCE |
GPIOLINE_FLAG_IS_OUT);
info->flags |= GPIO_V2_LINE_FLAG_OPEN_SOURCE;

if (test_bit(FLAG_BIAS_DISABLE, &desc->flags))
info->flags |= GPIOLINE_FLAG_BIAS_DISABLE;
info->flags |= GPIO_V2_LINE_FLAG_BIAS_DISABLED;
if (test_bit(FLAG_PULL_DOWN, &desc->flags))
info->flags |= GPIOLINE_FLAG_BIAS_PULL_DOWN;
info->flags |= GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN;
if (test_bit(FLAG_PULL_UP, &desc->flags))
info->flags |= GPIOLINE_FLAG_BIAS_PULL_UP;
info->flags |= GPIO_V2_LINE_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);
DECLARE_KFIFO(events, struct gpio_v2_line_info_changed, 32);
struct notifier_block lineinfo_changed_nb;
unsigned long *watched_lines;
#ifdef CONFIG_GPIO_CDEV_V1
atomic_t watch_abi_version;
#endif
};

#ifdef CONFIG_GPIO_CDEV_V1
/*
* returns 0 if the versions match, else the previously selected ABI version
*/
static int lineinfo_ensure_abi_version(struct gpio_chardev_data *cdata,
unsigned int version)
{
int abiv = atomic_cmpxchg(&cdata->watch_abi_version, 0, version);

if (abiv == version)
return 0;

return abiv;
}
#endif

static int lineinfo_get(struct gpio_chardev_data *cdev, void __user *ip,
bool watch)
{
struct gpio_desc *desc;
struct gpio_v2_line_info lineinfo;

if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
return -EFAULT;

if (memchr_inv(lineinfo.padding, 0, sizeof(lineinfo.padding)))
return -EINVAL;

desc = gpiochip_get_desc(cdev->gdev->chip, lineinfo.offset);
if (IS_ERR(desc))
return PTR_ERR(desc);

if (watch) {
#ifdef CONFIG_GPIO_CDEV_V1
if (lineinfo_ensure_abi_version(cdev, 2))
return -EPERM;
#endif
if (test_and_set_bit(lineinfo.offset, cdev->watched_lines))
return -EBUSY;
}
gpio_desc_to_lineinfo(desc, &lineinfo);

if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
if (watch)
clear_bit(lineinfo.offset, cdev->watched_lines);
return -EFAULT;
}

return 0;
}

/*
* gpio_ioctl() - ioctl handler for the GPIO chardev
*/
Expand All @@ -1242,7 +1342,6 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
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 */
Expand All @@ -1265,7 +1364,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
return 0;
#ifdef CONFIG_GPIO_CDEV_V1
} else if (cmd == GPIO_GET_LINEINFO_IOCTL) {
struct gpio_desc *desc;
struct gpioline_info lineinfo;
struct gpio_v2_line_info lineinfo_v2;

if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
return -EFAULT;
Expand All @@ -1275,7 +1376,8 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if (IS_ERR(desc))
return PTR_ERR(desc);

gpio_desc_to_lineinfo(desc, &lineinfo);
gpio_desc_to_lineinfo(desc, &lineinfo_v2);
gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);

if (copy_to_user(ip, &lineinfo, sizeof(lineinfo)))
return -EFAULT;
Expand All @@ -1285,7 +1387,9 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
} else if (cmd == GPIO_GET_LINEEVENT_IOCTL) {
return lineevent_create(gdev, ip);
} else if (cmd == GPIO_GET_LINEINFO_WATCH_IOCTL) {
struct gpio_desc *desc;
struct gpioline_info lineinfo;
struct gpio_v2_line_info lineinfo_v2;

if (copy_from_user(&lineinfo, ip, sizeof(lineinfo)))
return -EFAULT;
Expand All @@ -1295,10 +1399,14 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
if (IS_ERR(desc))
return PTR_ERR(desc);

if (lineinfo_ensure_abi_version(cdev, 1))
return -EPERM;

if (test_and_set_bit(lineinfo.line_offset, cdev->watched_lines))
return -EBUSY;

gpio_desc_to_lineinfo(desc, &lineinfo);
gpio_desc_to_lineinfo(desc, &lineinfo_v2);
gpio_v2_line_info_to_v1(&lineinfo_v2, &lineinfo);

if (copy_to_user(ip, &lineinfo, sizeof(lineinfo))) {
clear_bit(lineinfo.line_offset, cdev->watched_lines);
Expand All @@ -1307,6 +1415,10 @@ static long gpio_ioctl(struct file *file, unsigned int cmd, unsigned long arg)

return 0;
#endif /* CONFIG_GPIO_CDEV_V1 */
} else if (cmd == GPIO_V2_GET_LINEINFO_IOCTL ||
cmd == GPIO_V2_GET_LINEINFO_WATCH_IOCTL) {
return lineinfo_get(cdev, ip,
cmd == GPIO_V2_GET_LINEINFO_WATCH_IOCTL);
} else if (cmd == GPIO_V2_GET_LINE_IOCTL) {
return linereq_create(gdev, ip);
} else if (cmd == GPIO_GET_LINEINFO_UNWATCH_IOCTL) {
Expand Down Expand Up @@ -1342,7 +1454,7 @@ 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_v2_line_info_changed chg;
struct gpio_desc *desc = data;
int ret;

Expand All @@ -1351,7 +1463,7 @@ static int lineinfo_changed_notify(struct notifier_block *nb,

memset(&chg, 0, sizeof(chg));
chg.event_type = action;
chg.timestamp = ktime_get_ns();
chg.timestamp_ns = ktime_get_ns();
gpio_desc_to_lineinfo(desc, &chg.info);

ret = kfifo_in_spinlocked(&cdev->events, &chg, 1, &cdev->wait.lock);
Expand Down Expand Up @@ -1382,12 +1494,16 @@ 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;
struct gpio_v2_line_info_changed event;
ssize_t bytes_read = 0;
int ret;
size_t event_size;

if (count < sizeof(event))
#ifndef CONFIG_GPIO_CDEV_V1
event_size = sizeof(struct gpio_v2_line_info_changed);
if (count < event_size)
return -EINVAL;
#endif

do {
spin_lock(&cdev->wait.lock);
Expand All @@ -1409,7 +1525,17 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
return ret;
}
}

#ifdef CONFIG_GPIO_CDEV_V1
/* must be after kfifo check so watch_abi_version is set */
if (atomic_read(&cdev->watch_abi_version) == 2)
event_size = sizeof(struct gpio_v2_line_info_changed);
else
event_size = sizeof(struct gpioline_info_changed);
if (count < event_size) {
spin_unlock(&cdev->wait.lock);
return -EINVAL;
}
#endif
ret = kfifo_out(&cdev->events, &event, 1);
spin_unlock(&cdev->wait.lock);
if (ret != 1) {
Expand All @@ -1418,9 +1544,23 @@ static ssize_t lineinfo_watch_read(struct file *file, char __user *buf,
/* We should never get here. See lineevent_read(). */
}

if (copy_to_user(buf + bytes_read, &event, sizeof(event)))
#ifdef CONFIG_GPIO_CDEV_V1
if (event_size == sizeof(struct gpio_v2_line_info_changed)) {
if (copy_to_user(buf + bytes_read, &event, event_size))
return -EFAULT;
} else {
struct gpioline_info_changed event_v1;

gpio_v2_line_info_changed_to_v1(&event, &event_v1);
if (copy_to_user(buf + bytes_read, &event_v1,
event_size))
return -EFAULT;
}
#else
if (copy_to_user(buf + bytes_read, &event, event_size))
return -EFAULT;
bytes_read += sizeof(event);
#endif
bytes_read += event_size;
} while (count >= bytes_read + sizeof(event));

return bytes_read;
Expand Down

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