drivers/media/test-drivers/vivid/vivid-radio-tx.c

Source file repositories/reference/linux-study-clean/drivers/media/test-drivers/vivid/vivid-radio-tx.c

File Facts

System
Linux kernel
Corpus path
drivers/media/test-drivers/vivid/vivid-radio-tx.c
Extension
.c
Size
3640 bytes
Lines
129
Domain
Driver Families
Bucket
drivers/media
Inferred role
Driver Families: implementation source
Status
source implementation candidate

Why This File Exists

Repeatable hardware-adapter layer. Deep compatibility for every driver is out of scope; this atlas records patterns, probe lifecycles, bus glue, IRQ/DMA usage, and links back to core abstractions.

Dependency Surface

Detected Declarations

Annotated Snippet

file_to_v4l2_fh(file) != dev->radio_tx_rds_owner) {
		mutex_unlock(&dev->mutex);
		return -EBUSY;
	}
	dev->radio_tx_rds_owner = file_to_v4l2_fh(file);

retry:
	timestamp = ktime_sub(ktime_get(), dev->radio_rds_init_time);
	blk = ktime_divns(timestamp, VIVID_RDS_NSEC_PER_BLK);
	if (blk - VIVID_RDS_GEN_BLOCKS >= dev->radio_tx_rds_last_block)
		dev->radio_tx_rds_last_block = blk - VIVID_RDS_GEN_BLOCKS + 1;

	/*
	 * No data is available if there hasn't been time to get new data,
	 * or if the RDS receiver has been disabled, or if we use the data
	 * from the RDS transmitter and that RDS transmitter has been disabled,
	 * or if the signal quality is too weak.
	 */
	if (blk == dev->radio_tx_rds_last_block ||
	    !(dev->radio_tx_subchans & V4L2_TUNER_SUB_RDS)) {
		mutex_unlock(&dev->mutex);
		if (file->f_flags & O_NONBLOCK)
			return -EWOULDBLOCK;
		if (msleep_interruptible(20) && signal_pending(current))
			return -EINTR;
		if (mutex_lock_interruptible(&dev->mutex))
			return -ERESTARTSYS;
		goto retry;
	}

	for (i = 0; i < size && blk > dev->radio_tx_rds_last_block;
			dev->radio_tx_rds_last_block++) {
		unsigned data_blk = dev->radio_tx_rds_last_block % VIVID_RDS_GEN_BLOCKS;
		struct v4l2_rds_data rds;

		if (copy_from_user(&rds, buf + i, sizeof(rds))) {
			i = -EFAULT;
			break;
		}
		i += sizeof(rds);
		if (!dev->radio_rds_loop)
			continue;
		if ((rds.block & V4L2_RDS_BLOCK_MSK) == V4L2_RDS_BLOCK_INVALID ||
		    (rds.block & V4L2_RDS_BLOCK_ERROR))
			continue;
		rds.block &= V4L2_RDS_BLOCK_MSK;
		data[data_blk] = rds;
	}
	mutex_unlock(&dev->mutex);
	return i;
}

__poll_t vivid_radio_tx_poll(struct file *file, struct poll_table_struct *wait)
{
	return EPOLLOUT | EPOLLWRNORM | v4l2_ctrl_poll(file, wait);
}

int vidioc_g_modulator(struct file *file, void *priv, struct v4l2_modulator *a)
{
	struct vivid_dev *dev = video_drvdata(file);

	if (a->index > 0)
		return -EINVAL;

	strscpy(a->name, "AM/FM/SW Transmitter", sizeof(a->name));
	a->capability = V4L2_TUNER_CAP_LOW | V4L2_TUNER_CAP_STEREO |
			V4L2_TUNER_CAP_FREQ_BANDS | V4L2_TUNER_CAP_RDS |
			(dev->radio_tx_rds_controls ?
				V4L2_TUNER_CAP_RDS_CONTROLS :
				V4L2_TUNER_CAP_RDS_BLOCK_IO);
	a->rangelow = AM_FREQ_RANGE_LOW;
	a->rangehigh = FM_FREQ_RANGE_HIGH;
	a->txsubchans = dev->radio_tx_subchans;
	return 0;
}

int vidioc_s_modulator(struct file *file, void *priv, const struct v4l2_modulator *a)
{
	struct vivid_dev *dev = video_drvdata(file);

	if (a->index)
		return -EINVAL;
	if (a->txsubchans & ~0x13)
		return -EINVAL;
	dev->radio_tx_subchans = a->txsubchans;
	return 0;
}

Annotation

Implementation Notes