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Date:   Tue, 26 Jan 2021 17:56:29 +0200
From:   Laurent Pinchart <laurent.pinchart@ideasonboard.com>
To:     Ricardo Ribalda <ribalda@chromium.org>
Cc:     Mauro Carvalho Chehab <mchehab@kernel.org>,
        linux-media@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v7 06/12] media: uvcvideo: Implement UVC_EXT_GPIO_UNIT
Message-ID: <YBA7rduUYr0I/KwJ@pendragon.ideasonboard.com>
References: <20201223133528.55014-1-ribalda@chromium.org>
 <20201223133528.55014-7-ribalda@chromium.org>
 <YBA67sapYU3almJb@pendragon.ideasonboard.com>
MIME-Version: 1.0
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In-Reply-To: <YBA67sapYU3almJb@pendragon.ideasonboard.com>
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On Tue, Jan 26, 2021 at 05:53:19PM +0200, Laurent Pinchart wrote:
> Hi Ricardo,
> 
> Thank you for the patch.
> 
> On Wed, Dec 23, 2020 at 02:35:22PM +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 <ribalda@chromium.org>
> > ---
> >  drivers/media/usb/uvc/uvc_ctrl.c   |   3 +
> >  drivers/media/usb/uvc/uvc_driver.c | 127 +++++++++++++++++++++++++++++
> >  drivers/media/usb/uvc/uvc_entity.c |   1 +
> >  drivers/media/usb/uvc/uvcvideo.h   |  16 ++++
> >  4 files changed, 147 insertions(+)
> > 
> > diff --git a/drivers/media/usb/uvc/uvc_ctrl.c b/drivers/media/usb/uvc/uvc_ctrl.c
> > index 1a5e85368af4..e0ab55583dd8 100644
> > --- a/drivers/media/usb/uvc/uvc_ctrl.c
> > +++ b/drivers/media/usb/uvc/uvc_ctrl.c
> > @@ -2291,6 +2291,9 @@ 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..b0bf93c44999 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 +1469,108 @@ static int uvc_parse_control(struct uvc_device *dev)
> >  	return 0;
> >  }
> >  
> > +/* -----------------------------------------------------------------------------
> > + * Privacy GPIO
> > + */
> > +
> > +static void uvc_gpio_event(struct uvc_device *dev)
> > +{
> > +	struct uvc_entity *unit = dev->gpio_unit;
> > +	struct uvc_video_chain *chain;
> > +	u8 new_val;
> > +
> > +	if (!unit)
> > +		return;
> > +
> > +	new_val = gpiod_get_value_cansleep(unit->gpio.gpio_privacy);
> > +
> > +	/* GPIO entities are always on the first chain. */
> > +	chain = list_first_entry(&dev->chains, struct uvc_video_chain, list);
> > +	uvc_ctrl_status_event(chain, unit->controls, &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)
> > +		return -EINVAL;
> > +
> > +	*(u8 *)data = gpiod_get_value_cansleep(entity->gpio.gpio_privacy);
> > +
> > +	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;
> > +
> > +	uvc_gpio_event(dev);
> 
> Should uvc_gpio_event() be inlined here ? If so I can make the
> modification when applying, there's no need for a v8 just for this.

I've seen the function is called in a different location later in this
series, please ignore the noise.

> Reviewed-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>
> 
> > +	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 < 0) {
> > +		if (irq != EPROBE_DEFER)
> > +			dev_err(&dev->udev->dev,
> > +				"No IRQ for privacy GPIO (%d)\n", irq);
> > +		return irq;
> > +	}
> > +
> > +	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,
> > +					 "uvc_privacy_gpio", dev);
> > +}
> > +
> >  /* ------------------------------------------------------------------------
> >   * UVC device scan
> >   */
> > @@ -1953,6 +2060,13 @@ 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 +2399,12 @@ 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 +2449,13 @@ static int uvc_probe(struct usb_interface *intf,
> >  			"supported.\n", ret);
> >  	}
> >  
> > +	ret = uvc_gpio_init_irq(dev);
> > +	if (ret < 0) {
> > +		dev_err(&dev->udev->dev,
> > +			"Unable to request privacy GPIO IRQ (%d)\n", ret);
> > +		goto error;
> > +	}
> > +
> >  	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 6465711fe5bb..4211531a3558 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, \
> > @@ -212,6 +218,7 @@
> >   * Structures.
> >   */
> >  
> > +struct gpio_desc;
> >  struct uvc_device;
> >  
> >  /* TODO: Put the most frequently accessed fields at the beginning of
> > @@ -353,6 +360,13 @@ struct uvc_entity {
> >  			u8  *bmControls;
> >  			u8  *bmControlsType;
> >  		} extension;
> > +
> > +		struct {
> > +			u8  bControlSize;
> > +			u8  *bmControls;
> > +			struct gpio_desc *gpio_privacy;
> > +			int irq;
> > +		} gpio;
> >  	};
> >  
> >  	u8 bNrInPins;
> > @@ -690,6 +704,8 @@ struct uvc_device {
> >  		struct uvc_control *ctrl;
> >  		const void *data;
> >  	} async_ctrl;
> > +
> > +	struct uvc_entity *gpio_unit;
> >  };
> >  
> >  enum uvc_handle_state {

-- 
Regards,

Laurent Pinchart