V4L/DVB (4722): Cx88: Add support for VIDIOC_INT_[SR]_REGISTER ioctls

Add support for the advanced debugging ioctls, to allow access to the
cx88 registers from userspace.  Only i2c_id == 0 is supported, for access
to the cx88 adapter itself.  There isn't any support for access to I2C
clients of the adapter.  Most of them don't have R/W registers anyway,
and its necessary to use i2c-dev to talk to them from userspace.

Signed-off-by: Trent Piepho <xyzzy@speakeasy.org>
Signed-off-by: Mauro Carvalho Chehab <mchehab@infradead.org>

drivers/media/video/cx88/cx88-video.c

@@ -1490,6 +1490,30 @@ int cx88_do_ioctl(struct inode *inode, struct file *file, int radio,
 		mutex_unlock(&core->lock);
 		return 0;
 	}
+#ifdef CONFIG_VIDEO_ADV_DEBUG
+	/* ioctls to allow direct acces to the cx2388x registers */
+	case VIDIOC_INT_G_REGISTER:
+	{
+		struct v4l2_register *reg = arg;
+
+		if (reg->i2c_id != 0)
+			return -EINVAL;
+		/* cx2388x has a 24-bit register space */
+		reg->val = cx_read(reg->reg&0xffffff);
+		return 0;
+	}
+	case VIDIOC_INT_S_REGISTER:
+	{
+		struct v4l2_register *reg = arg;
+
+		if (reg->i2c_id != 0)
+			return -EINVAL;
+		if (!capable(CAP_SYS_ADMIN))
+			return -EPERM;
+		cx_write(reg->reg&0xffffff, reg->val);
+		return 0;
+	}
+#endif
 
 	default:
 		return v4l_compat_translate_ioctl(inode,file,cmd,arg,