drivers/media/pci/pt3/pt3_dma.c

Source file repositories/reference/linux-study-clean/drivers/media/pci/pt3/pt3_dma.c

File Facts

System
Linux kernel
Corpus path
drivers/media/pci/pt3/pt3_dma.c
Extension
.c
Size
4997 bytes
Lines
217
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

else if (adap->buf_ofs + PT3_ACCESS_UNIT > DATA_BUF_SZ) {
			dvb_dmx_swfilter_packets(&adap->demux, p,
				(DATA_BUF_SZ - adap->buf_ofs) / TS_PACKET_SZ);
			dvb_dmx_swfilter_packets(&adap->demux,
				adap->buffer[idx].data, ofs / TS_PACKET_SZ);
		} else
			dvb_dmx_swfilter_packets(&adap->demux, p,
				PT3_ACCESS_UNIT / TS_PACKET_SZ);

		*p = PT3_BUF_CANARY;
		adap->buf_idx = idx;
		adap->buf_ofs = ofs;
	}
	return 0;
}

void pt3_init_dmabuf(struct pt3_adapter *adap)
{
	int idx, ofs;
	u8 *p;

	idx = 0;
	ofs = 0;
	p = adap->buffer[0].data;
	/* mark the whole buffers as "not written yet" */
	while (idx < adap->num_bufs) {
		p[ofs] = PT3_BUF_CANARY;
		ofs += PT3_ACCESS_UNIT;
		if (ofs >= DATA_BUF_SZ) {
			ofs -= DATA_BUF_SZ;
			idx++;
			p = adap->buffer[idx].data;
		}
	}
	adap->buf_idx = 0;
	adap->buf_ofs = 0;
}

void pt3_free_dmabuf(struct pt3_adapter *adap)
{
	struct pt3_board *pt3;
	int i;

	pt3 = adap->dvb_adap.priv;
	for (i = 0; i < adap->num_bufs; i++)
		dma_free_coherent(&pt3->pdev->dev, DATA_BUF_SZ,
			adap->buffer[i].data, adap->buffer[i].b_addr);
	adap->num_bufs = 0;

	for (i = 0; i < adap->num_desc_bufs; i++)
		dma_free_coherent(&pt3->pdev->dev, PAGE_SIZE,
			adap->desc_buf[i].descs, adap->desc_buf[i].b_addr);
	adap->num_desc_bufs = 0;
}


int pt3_alloc_dmabuf(struct pt3_adapter *adap)
{
	struct pt3_board *pt3;
	void *p;
	int i, j;
	int idx, ofs;
	int num_desc_bufs;
	dma_addr_t data_addr, desc_addr;
	struct xfer_desc *d;

	pt3 = adap->dvb_adap.priv;
	adap->num_bufs = 0;
	adap->num_desc_bufs = 0;
	for (i = 0; i < pt3->num_bufs; i++) {
		p = dma_alloc_coherent(&pt3->pdev->dev, DATA_BUF_SZ,
					&adap->buffer[i].b_addr, GFP_KERNEL);
		if (p == NULL)
			goto failed;
		adap->buffer[i].data = p;
		adap->num_bufs++;
	}
	pt3_init_dmabuf(adap);

	/* build circular-linked pointers (xfer_desc) to the data buffers*/
	idx = 0;
	ofs = 0;
	num_desc_bufs =
		DIV_ROUND_UP(adap->num_bufs * DATA_BUF_XFERS, DESCS_IN_PAGE);
	for (i = 0; i < num_desc_bufs; i++) {
		p = dma_alloc_coherent(&pt3->pdev->dev, PAGE_SIZE,
					&desc_addr, GFP_KERNEL);
		if (p == NULL)
			goto failed;
		adap->num_desc_bufs++;

Annotation

Implementation Notes