bus_managers/scsi/dma_buffer.cpp

9 	DMA buffer handling.
12 	is DMA safe, we check that and copy data to a buffer if needed.
13 	The buffer is enlarged on demand and destroyed after a time-out
21 	Currently, there is only one buffer per device; in the future,
96 /** copy data from/to DMA buffer */
101 	dma_buffer *buffer = request->dma_buffer;
102 	const physical_entry *sg_list = buffer->sg_list_orig;
103 	uint32 num_vecs = buffer->sg_count_orig;
104 	uchar *buffer_data = buffer->address;
111 	// we have to use S/G list to original data; the DMA buffer
133 scsi_free_dma_buffer(dma_buffer *buffer)
135 	if (buffer->area > 0) {
136 		SHOW_FLOW0(1, "Destroying buffer");
138 		delete_area(buffer->area);
139 		buffer->area = 0;
140 		buffer->size = 0;
143 	if (buffer->sg_list_area > 0) {
144 		delete_area(buffer->sg_list_area);
145 		buffer->sg_list_area = 0;
150 /**	allocate dma buffer for given device, deleting old one
151  *	size - buffer size in bytes
155 scsi_alloc_dma_buffer(dma_buffer *buffer, dma_params *dma_params, uint32 size)
157 	// free old buffer first
158 	scsi_free_dma_buffer(buffer);
171 		// alright - a contiguous buffer is required to keep S/G table short
172 		SHOW_INFO(1, "need to setup contiguous DMA buffer of size %" B_PRIu32,
195 		buffer->area = create_area_etc(B_SYSTEM_TEAM, "DMA buffer", size,
198 			(void**)&buffer->address);
200 		if (buffer->area < 0) {
201 			SHOW_ERROR(2, "Cannot create contignous DMA buffer of %" B_PRIu32
206 		buffer->size = size;
208 		// we can live with a fragmented buffer - very nice
209 		buffer->area = create_area("DMA buffer",
210 			(void **)&buffer->address, B_ANY_KERNEL_ADDRESS, size,
213 		if (buffer->area < 0) {
214 			SHOW_ERROR(2, "Cannot create DMA buffer of %" B_PRIu32 " bytes",
219 		buffer->size = size;
224 	size_t sg_list_size = buffer->size / B_PAGE_SIZE * sizeof( physical_entry );
228 	buffer->sg_list_area = create_area("DMA buffer S/G table",
229 		(void **)&buffer->sg_list, B_ANY_KERNEL_ADDRESS, sg_list_size,
232 	if (buffer->sg_list_area < 0) {
233 		SHOW_ERROR( 2, "Cannot create DMA buffer S/G list of %" B_PRIuSIZE
236 		delete_area(buffer->area);
237 		buffer->area = 0;
247 			buffer->address,
248 			buffer->size
252 			&vec, 1, 0, buffer->size,
253 			buffer->sg_list, sg_list_entries, &buffer->sg_count,
256 		if( res != B_OK || mapped_len != buffer->size ) {
257 			SHOW_ERROR(0, "Error creating S/G list for DMA buffer (%s; wanted "
259 				mapped_len, buffer->size);
268 scsi_free_dma_buffer_sg_orig(dma_buffer *buffer)
270 	if (buffer->sg_orig > 0) {
271 		delete_area(buffer->sg_orig);
272 		buffer->sg_orig = 0;
273 		buffer->sg_count_max_orig = 0;
281 scsi_alloc_dma_buffer_sg_orig(dma_buffer *buffer, size_t size)
284 	scsi_free_dma_buffer_sg_orig(buffer);
288 	buffer->sg_orig = create_area("S/G to original data",
289 		(void **)&buffer->sg_list_orig,
292 	if (buffer->sg_orig < 0) {
293 		SHOW_ERROR(2, "Cannot S/G list buffer to original data of %" B_PRIuSIZE
298 	buffer->sg_count_max_orig = size / sizeof(physical_entry);
301 		buffer->sg_count_max_orig);
326 scsi_dma_buffer_compose_sg_orig(dma_buffer *buffer, scsi_ccb *request)
328 	// enlarge buffer is required
329 	if (buffer->sg_count_max_orig < request->sg_count) {
330 		if (!scsi_alloc_dma_buffer_sg_orig(buffer, request->sg_count))
336 	memcpy(buffer->sg_list_orig, request->sg_list,
339 	buffer->sg_count_orig = request->sg_count;
344 /**	init DMA buffer and copy data to it if required
352 	dma_buffer *buffer;
364 	// only one buffer at a time
370 	// there is only one buffer, so no further management
371 	buffer = &device->dma_buffer;
373 	buffer->inuse = true;
377 	// memorize buffer for cleanup
378 	request->dma_buffer = buffer;
380 	// enlarge buffer if too small
381 	if (buffer->size < request->data_length) {
382 		if (!scsi_alloc_dma_buffer(buffer, &device->bus->dma_params,
387 	// create S/G to original data (necessary for copying from-buffer on end
388 	// of request, but also used during copying to-buffer in a second because
392 	// copy data to buffer
398 	// replace data address, so noone notices that a buffer is used
399 	buffer->orig_data = request->data;
400 	buffer->orig_sg_list = request->sg_list;
401 	buffer->orig_sg_count = request->sg_count;
403 	request->data = buffer->address;
404 	request->sg_list = buffer->sg_list;
405 	request->sg_count = buffer->sg_count;
414 	SHOW_INFO0(3, "error setting up DMA buffer");
419 	buffer->inuse = false;
428 /*!	Copy data back and release DMA buffer;
435 	dma_buffer *buffer = request->dma_buffer;
441 	// copy data from buffer if required and if operation succeeded
447 	request->data = buffer->orig_data;
448 	request->sg_list = buffer->orig_sg_list;
449 	request->sg_count = buffer->orig_sg_count;
451 	// free buffer
454 	buffer->last_use = system_time();
455 	buffer->inuse = false;
465 /** dameon that deletes DMA buffer if not used for some time */
471 	dma_buffer *buffer;
475 	buffer = &device->dma_buffer;
477 	if (!buffer->inuse
478 		&& buffer->last_use - system_time() > SCSI_DMA_BUFFER_CLEANUP_DELAY) {
479 		scsi_free_dma_buffer(buffer);
480 		scsi_free_dma_buffer_sg_orig(buffer);
488 scsi_dma_buffer_free(dma_buffer *buffer)
490 	scsi_free_dma_buffer(buffer);
491 	scsi_free_dma_buffer_sg_orig(buffer);
496 scsi_dma_buffer_init(dma_buffer *buffer)
498 	buffer->area = 0;
499 	buffer->size = 0;
500 	buffer->sg_orig = 0;
501 	buffer->sg_count_max_orig = 0;