Some devices can implement a physical switch to disable the input of the
camera on demand. Think of it like an elegant privacy sticker.
The system can read the status of the privacy switch via a GPIO.
It is important to know the status of the switch, e.g. to notify the
user when the camera will produce black frames and a videochat
application is used.
Since the uvc device is not aware of this pin (and it should't), we need
to implement a virtual entity that can interact with such pin.
The location of the GPIO is specified via acpi or DT. on the usb device Eg:
Name (_CRS, ResourceTemplate () // _CRS: Current Resource Settings
{
GpioIo (Exclusive, PullDefault, 0x0000, 0x0000, IoRestrictionOutputOnly,
"\\_SB.PCI0.GPIO", 0x00, ResourceConsumer, ,
)
{ // Pin list
0x0064
}
})
Name (_DSD, Package (0x02) // _DSD: Device-Specific Data
{
ToUUID ("daffd814-6eba-4d8c-8a91-bc9bbf4aa301") /* Device Properties
for _DSD */,
Package (0x01)
{
Package (0x02)
{
"privacy-gpio",
Package (0x04)
{
\_SB.PCI0.XHCI.RHUB.HS07,
Zero,
Zero,
One
}
}
}
})
Signed-off-by: Ricardo Ribalda <riba...@chromium.org>
---
drivers/media/usb/uvc/uvc_ctrl.c | 3 ++
drivers/media/usb/uvc/uvc_driver.c | 72 ++++++++++++++++++++++++++++++
drivers/media/usb/uvc/uvcvideo.h | 8 ++++
3 files changed, 83 insertions(+)
diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
index 786498e66646..3a49a1326a90 100644
--- a/drivers/media/usb/uvc/uvc_ctrl.c
+++ b/drivers/media/usb/uvc/uvc_ctrl.c
@@ -2332,6 +2332,9 @@ int uvc_ctrl_init_device(struct uvc_device *dev)
} else if (UVC_ENTITY_TYPE(entity) == UVC_ITT_CAMERA) {
bmControls = entity->camera.bmControls;
bControlSize = entity->camera.bControlSize;
+ } else if (UVC_ENTITY_TYPE(entity) == UVC_GPIO_UNIT) {
+ bmControls = entity->gpio.bmControls;
+ bControlSize = entity->gpio.bControlSize;
}
/* Remove bogus/blacklisted controls */
diff --git a/drivers/media/usb/uvc/uvc_driver.c
b/drivers/media/usb/uvc/uvc_driver.c
index ddb9eaa11be7..180e503e900f 100644
--- a/drivers/media/usb/uvc/uvc_driver.c
+++ b/drivers/media/usb/uvc/uvc_driver.c
@@ -7,6 +7,7 @@
*/
#include <linux/atomic.h>
+#include <linux/gpio/consumer.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/module.h>
@@ -1440,6 +1441,58 @@ static int uvc_parse_control(struct uvc_device *dev)
return 0;
}
+static int uvc_gpio_get_cur(struct uvc_entity *entity, u8 cs, void *data, u16
size)
+{
+ if ((cs != UVC_CT_PRIVACY_CONTROL) || (size < 1))
+ return -EINVAL;
+
+ *(uint8_t *)data = gpiod_get_value(entity->gpio.gpio_privacy);
+ return 0;
+}
+
+static int uvc_gpio_get_info(struct uvc_entity *entity, u8 cs, u8 *caps)
+{
+
+ if (cs != UVC_CT_PRIVACY_CONTROL)
+ return -EINVAL;
+
+ *caps = UVC_CONTROL_CAP_GET | UVC_CONTROL_CAP_AUTOUPDATE;
+ return 0;
+}
+
+static int uvc_parse_gpio(struct uvc_device *dev)
+{
+ struct uvc_entity *unit;
+ struct gpio_desc *gpio_privacy;
+ int irq;
+ int ret;
+
+ gpio_privacy = devm_gpiod_get_optional(&dev->udev->dev, "privacy",
GPIOD_IN);
+
+ if (IS_ERR(gpio_privacy))
+ return PTR_ERR(gpio_privacy);
+
+ if (!gpio_privacy)
+ return 0;
+
+ unit = uvc_alloc_entity(UVC_GPIO_UNIT, 0xff, 1, 2);
+ if (!unit)
+ return -ENOMEM;
+
+ unit->gpio.gpio_privacy = gpio_privacy;
+ unit->gpio.bControlSize = 1;
+ unit->gpio.bmControls = (u8 *)unit + sizeof(*unit);
+ unit->gpio.bmControls[0] = 1;
+ unit->get_cur = uvc_gpio_get_cur;
+ unit->get_info = uvc_gpio_get_info;
+
+ sprintf(unit->name, "GPIO Unit");
+
+ list_add_tail(&unit->list, &dev->entities);
+
+ return 0;
+}
+
/* ------------------------------------------------------------------------
* UVC device scan
*/
@@ -1532,6 +1585,12 @@ static int uvc_scan_chain_entity(struct uvc_video_chain
*chain,
break;
+ case UVC_GPIO_UNIT:
+ if (uvc_trace_param & UVC_TRACE_PROBE)
+ printk(KERN_CONT " GPIO %d", entity->id);
+
+ break;
+
case UVC_TT_STREAMING:
if (UVC_ENTITY_IS_ITERM(entity)) {
if (uvc_trace_param & UVC_TRACE_PROBE)
@@ -1929,6 +1988,13 @@ static int uvc_scan_device(struct uvc_device *dev)
return -1;
}
+ /* Add GPIO entities to the first_chain */
+ chain = list_first_entry(&dev->chains, struct uvc_video_chain, list);
+ list_for_each_entry(term, &dev->entities, list) {
+ if (UVC_ENTITY_TYPE(term) == UVC_GPIO_UNIT)
+ list_add_tail(&term->chain, &chain->entities);
+ }
+
return 0;
}
@@ -2261,6 +2327,12 @@ static int uvc_probe(struct usb_interface *intf,
goto error;
}
+ /* Parse the associated GPIOs */
+ if (uvc_parse_gpio(dev) < 0) {
+ uvc_trace(UVC_TRACE_PROBE, "Unable to parse UVC GPIOs\n");
+ goto error;
+ }
+
uvc_printk(KERN_INFO, "Found UVC %u.%02x device %s (%04x:%04x)\n",
dev->uvc_version >> 8, dev->uvc_version & 0xff,
udev->product ? udev->product : "<unnamed>",
diff --git a/drivers/media/usb/uvc/uvcvideo.h b/drivers/media/usb/uvc/uvcvideo.h
index a493bc383d3e..7ca78005b6a9 100644
--- a/drivers/media/usb/uvc/uvcvideo.h
+++ b/drivers/media/usb/uvc/uvcvideo.h
@@ -6,6 +6,7 @@
#error "The uvcvideo.h header is deprecated, use linux/uvcvideo.h instead."
#endif /* __KERNEL__ */
+#include <linux/gpio/consumer.h>
#include <linux/kernel.h>
#include <linux/poll.h>
#include <linux/usb.h>
@@ -37,6 +38,7 @@
(UVC_ENTITY_IS_TERM(entity) && \
((entity)->type & 0x8000) == UVC_TERM_OUTPUT)
+#define UVC_GPIO_UNIT 0x7ffe
/* ------------------------------------------------------------------------
* GUIDs
@@ -351,6 +353,12 @@ struct uvc_entity {
u8 *bmControls;
u8 *bmControlsType;
} extension;
+
+ struct {
+ u8 bControlSize;
+ u8 *bmControls;
+ struct gpio_desc *gpio_privacy;
+ } gpio;
};
u8 bNrInPins;
--
2.29.0.rc1.297.gfa9743e501-goog
