Hi Ricardo,

Thank you for the patch.

On Wed, Dec 23, 2020 at 12:04:41AM +0100, Ricardo Ribalda wrote:
> 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.
> 
> In some systems, the GPIO is connected to main SoC instead of the

s/to main/to the main/

> camera controller, with the connection reported by the system firmware
> (ACPI or DT). In that case, the UVC device isn't aware of the GPIO. We
> need to implement a virtual entity to handle the GPIO fully on the
> driver side.
> 
> For example, for ACPI-based systems, the GPIO is reported in the USB
> device object:
> 
>   Scope (\_SB.PCI0.XHCI.RHUB.HS07)
>   {
> 
>         /.../
> 
>     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 | 133 +++++++++++++++++++++++++++++
>  drivers/media/usb/uvc/uvc_entity.c |   1 +
>  drivers/media/usb/uvc/uvcvideo.h   |  17 ++++
>  4 files changed, 154 insertions(+)
> 
> diff --git a/drivers/media/usb/uvc/uvc_ctrl.c 
> b/drivers/media/usb/uvc/uvc_ctrl.c
> index acdc9b032306..22857b6a71e2 100644
> --- a/drivers/media/usb/uvc/uvc_ctrl.c
> +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> @@ -2311,6 +2311,9 @@ 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_EXT_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 c0c5f75ade40..5873237bbfa8 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>
> @@ -1020,6 +1021,7 @@ static int uvc_parse_streaming(struct uvc_device *dev,
>  }
>  
>  static const u8 uvc_camera_guid[16] = UVC_GUID_UVC_CAMERA;
> +static const u8 uvc_gpio_guid[16] = UVC_GUID_EXT_GPIO_CONTROLLER;
>  static const u8 uvc_media_transport_input_guid[16] =
>       UVC_GUID_UVC_MEDIA_TRANSPORT_INPUT;
>  static const u8 uvc_processing_guid[16] = UVC_GUID_UVC_PROCESSING;
> @@ -1051,6 +1053,9 @@ static struct uvc_entity *uvc_alloc_entity(u16 type, 
> u16 id,
>        * is initialized by the caller.
>        */
>       switch (type) {
> +     case UVC_EXT_GPIO_UNIT:
> +             memcpy(entity->guid, uvc_gpio_guid, 16);
> +             break;
>       case UVC_ITT_CAMERA:
>               memcpy(entity->guid, uvc_camera_guid, 16);
>               break;
> @@ -1464,6 +1469,115 @@ static int uvc_parse_control(struct uvc_device *dev)
>       return 0;
>  }
>  
> +/* 
> -----------------------------------------------------------------------------
> + * Privacy GPIO
> + */
> +
> +static u8 uvc_gpio_update_value(struct uvc_device *dev)
> +{
> +     struct uvc_entity *unit = dev->gpio_unit;
> +     struct uvc_video_chain *chain;
> +     u8 gpio_val, old_val, new_val;
> +
> +     gpio_val = new_val = gpiod_get_value_cansleep(unit->gpio.gpio_privacy);
> +
> +     old_val = atomic_xchg(&unit->gpio.gpio_privacy_value, gpio_val);
> +     if (new_val == old_val)
> +             return new_val;
> +
> +     /* GPIO entities are always on the first chain. */
> +     chain = list_first_entry(&dev->chains, struct uvc_video_chain, list);
> +     uvc_ctrl_status_event_direct(chain, unit->controls, &new_val);
> +
> +     return new_val;
> +}
> +
> +static int uvc_gpio_get_cur(struct uvc_device *dev, struct uvc_entity 
> *entity,
> +                         u8 cs, void *data, u16 size)
> +{
> +     if (cs != UVC_CT_PRIVACY_CONTROL || size < 1 || !dev->gpio_unit)
> +             return -EINVAL;
> +
> +     *(u8 *)data = uvc_gpio_update_value(dev);
> +
> +     return 0;
> +}
> +
> +static int uvc_gpio_get_info(struct uvc_device *dev, 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 irqreturn_t uvc_gpio_irq(int irq, void *data)
> +{
> +     struct uvc_device *dev = data;
> +
> +     if (!dev->gpio_unit)
> +             return IRQ_HANDLED;
> +
> +     uvc_gpio_update_value(dev);
> +     return IRQ_HANDLED;
> +}
> +
> +static int uvc_gpio_parse(struct uvc_device *dev)
> +{
> +     struct uvc_entity *unit;
> +     struct gpio_desc *gpio_privacy;
> +     int irq;
> +
> +     gpio_privacy = devm_gpiod_get_optional(&dev->udev->dev, "privacy",
> +                                            GPIOD_IN);
> +     if (IS_ERR_OR_NULL(gpio_privacy))
> +             return PTR_ERR_OR_ZERO(gpio_privacy);
> +
> +     unit = uvc_alloc_entity(UVC_EXT_GPIO_UNIT, UVC_EXT_GPIO_UNIT_ID, 0, 1);
> +     if (!unit)
> +             return -ENOMEM;
> +
> +     irq = gpiod_to_irq(gpio_privacy);
> +     if (irq == -EPROBE_DEFER)
> +             return -EPROBE_DEFER;
> +
> +     if (irq < 0)
> +             dev_warn(&dev->udev->dev,
> +                      "No IRQ for privacy GPIO (%d)\n", irq);
> +
> +     atomic_set(&unit->gpio.gpio_privacy_value, -1);
> +     unit->gpio.gpio_privacy = gpio_privacy;
> +     unit->gpio.irq = irq;
> +     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;
> +     strncpy(unit->name, "GPIO", sizeof(unit->name) - 1);
> +
> +     list_add_tail(&unit->list, &dev->entities);
> +
> +     dev->gpio_unit = unit;
> +
> +     return 0;
> +}
> +
> +static int uvc_gpio_init_irq(struct uvc_device *dev)
> +{
> +     struct uvc_entity *unit = dev->gpio_unit;
> +
> +     if (!unit || unit->gpio.irq < 0)
> +             return 0;
> +
> +     return devm_request_threaded_irq(&dev->udev->dev, unit->gpio.irq, NULL,
> +                                      uvc_gpio_irq,
> +                                      IRQF_ONESHOT | IRQF_TRIGGER_FALLING |
> +                                        IRQF_TRIGGER_RISING,

Is there any good tool that could check indentation in a git hook ? ;-)

> +                                      "uvc_privacy_gpio", dev);
> +}
> +
>  /* ------------------------------------------------------------------------
>   * UVC device scan
>   */
> @@ -1953,6 +2067,13 @@ static int uvc_scan_device(struct uvc_device *dev)
>               return -1;
>       }
>  
> +     /* Add GPIO entity to the first chain. */
> +     if (dev->gpio_unit) {
> +             chain = list_first_entry(&dev->chains,
> +                                      struct uvc_video_chain, list);
> +             list_add_tail(&dev->gpio_unit->chain, &chain->entities);
> +     }
> +
>       return 0;
>  }
>  
> @@ -2285,6 +2406,12 @@ static int uvc_probe(struct usb_interface *intf,
>               goto error;
>       }
>  
> +     /* Parse the associated GPIOs. */
> +     if (uvc_gpio_parse(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>",
> @@ -2329,6 +2456,12 @@ static int uvc_probe(struct usb_interface *intf,
>                       "supported.\n", ret);
>       }
>  
> +     ret = uvc_gpio_init_irq(dev);
> +     if (ret < 0)
> +             dev_warn(&dev->udev->dev,
> +                      "Unable to request privacy GPIO IRQ %d. Continuing 
> without privacy events\n",
> +                      ret);
> +
>       uvc_trace(UVC_TRACE_PROBE, "UVC device initialized.\n");
>       usb_enable_autosuspend(udev);
>       return 0;
> diff --git a/drivers/media/usb/uvc/uvc_entity.c 
> b/drivers/media/usb/uvc/uvc_entity.c
> index ca3a9c2eec27..6a9ba5b498db 100644
> --- a/drivers/media/usb/uvc/uvc_entity.c
> +++ b/drivers/media/usb/uvc/uvc_entity.c
> @@ -105,6 +105,7 @@ static int uvc_mc_init_entity(struct uvc_video_chain 
> *chain,
>               case UVC_OTT_DISPLAY:
>               case UVC_OTT_MEDIA_TRANSPORT_OUTPUT:
>               case UVC_EXTERNAL_VENDOR_SPECIFIC:
> +             case UVC_EXT_GPIO_UNIT:
>               default:
>                       function = MEDIA_ENT_F_V4L2_SUBDEV_UNKNOWN;
>                       break;
> diff --git a/drivers/media/usb/uvc/uvcvideo.h 
> b/drivers/media/usb/uvc/uvcvideo.h
> index 64a3d901db19..132513a66ee5 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/atomic.h>
>  #include <linux/kernel.h>
>  #include <linux/poll.h>
>  #include <linux/usb.h>
> @@ -37,6 +38,8 @@
>       (UVC_ENTITY_IS_TERM(entity) && \
>       ((entity)->type & 0x8000) == UVC_TERM_OUTPUT)
>  
> +#define UVC_EXT_GPIO_UNIT            0x7ffe
> +#define UVC_EXT_GPIO_UNIT_ID         0x100
>  
>  /* ------------------------------------------------------------------------
>   * GUIDs
> @@ -56,6 +59,9 @@
>  #define UVC_GUID_UVC_SELECTOR \
>       {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
>        0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x02}
> +#define UVC_GUID_EXT_GPIO_CONTROLLER \
> +     {0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, \
> +      0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x03}
>  
>  #define UVC_GUID_FORMAT_MJPEG \
>       { 'M',  'J',  'P',  'G', 0x00, 0x00, 0x10, 0x00, \
> @@ -213,6 +219,7 @@
>   */
>  
>  struct uvc_device;
> +struct gpio_desc;

Alphabetical order ? :-)

Otherwise this looks good, pending an agreement on how to handle the
case where the GPIO can't generate an IRQ.

>  
>  /* TODO: Put the most frequently accessed fields at the beginning of
>   * structures to maximize cache efficiency.
> @@ -353,6 +360,14 @@ struct uvc_entity {
>                       u8  *bmControls;
>                       u8  *bmControlsType;
>               } extension;
> +
> +             struct {
> +                     u8  bControlSize;
> +                     u8  *bmControls;
> +                     struct gpio_desc *gpio_privacy;
> +                     int irq;
> +                     atomic_t gpio_privacy_value;
> +             } gpio;
>       };
>  
>       u8 bNrInPins;
> @@ -690,6 +705,8 @@ struct uvc_device {
>               struct uvc_control *ctrl;
>               const void *data;
>       } async_ctrl;
> +
> +     struct uvc_entity *gpio_unit;
>  };
>  
>  enum uvc_handle_state {

-- 
Regards,

Laurent Pinchart

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