int dma_alloc_descriptors(DMA_Handle_t handle, /* */
dmacHw_TRANSFER_TYPE_e transferType, /* */
dma_addr_t srcData, /* */
dma_addr_t dstData, /* */
size_t numBytes /* */
) {
DMA_Channel_t *channel;
DMA_DeviceAttribute_t *devAttr;
int numDescriptors;
size_t ringBytesRequired;
int rc = 0;
channel = HandleToChannel(handle);
if (channel == NULL) {
return -ENODEV;
}
devAttr = &DMA_gDeviceAttribute[channel->devType];
if (devAttr->config.transferType != transferType) {
return -EINVAL;
}
/* */
/* */
/* */
numDescriptors = dmacHw_calculateDescriptorCount(&devAttr->config,
(void *)srcData,
(void *)dstData,
numBytes);
if (numDescriptors < 0) {
printk(KERN_ERR "%s: dmacHw_calculateDescriptorCount failed\n",
__func__);
return -EINVAL;
}
/* */
/* */
ringBytesRequired = dmacHw_descriptorLen(numDescriptors);
/* */
if (ringBytesRequired > devAttr->ring.bytesAllocated) {
/* */
/* */
/* */
might_sleep();
/* */
dma_free_descriptor_ring(&devAttr->ring);
/* */
rc =
dma_alloc_descriptor_ring(&devAttr->ring,
numDescriptors);
if (rc < 0) {
printk(KERN_ERR
"%s: dma_alloc_descriptor_ring(%d) failed\n",
__func__, numDescriptors);
return rc;
}
/* */
if (dmacHw_initDescriptor(devAttr->ring.virtAddr,
devAttr->ring.physAddr,
devAttr->ring.bytesAllocated,
numDescriptors) < 0) {
printk(KERN_ERR "%s: dmacHw_initDescriptor failed\n",
__func__);
return -EINVAL;
}
} else {
/* */
/* */
dmacHw_resetDescriptorControl(devAttr->ring.virtAddr);
}
/* */
/* */
if (dmacHw_setDataDescriptor(&devAttr->config,
devAttr->ring.virtAddr,
(void *)srcData,
(void *)dstData, numBytes) < 0) {
printk(KERN_ERR "%s: dmacHw_setDataDescriptor failed\n",
__func__);
return -EINVAL;
}
/* */
/* */
devAttr->prevSrcData = srcData;
devAttr->prevDstData = dstData;
devAttr->prevNumBytes = numBytes;
return 0;
}
int dma_alloc_descriptors(DMA_Handle_t handle, /* DMA Handle */
dmacHw_TRANSFER_TYPE_e transferType, /* Type of transfer being performed */
dma_addr_t srcData, /* Place to get data to write to device */
dma_addr_t dstData, /* Pointer to device data address */
size_t numBytes /* Number of bytes to transfer to the device */
) {
DMA_Channel_t *channel;
DMA_DeviceAttribute_t *devAttr;
int numDescriptors;
size_t ringBytesRequired;
int rc = 0;
channel = HandleToChannel(handle);
if (channel == NULL) {
return -ENODEV;
}
devAttr = &DMA_gDeviceAttribute[channel->devType];
if (devAttr->config.transferType != transferType) {
return -EINVAL;
}
/* Figure out how many descriptors we need. */
/* printk("srcData: 0x%08x dstData: 0x%08x, numBytes: %d\n", */
/* srcData, dstData, numBytes); */
numDescriptors = dmacHw_calculateDescriptorCount(&devAttr->config,
(void *)srcData,
(void *)dstData,
numBytes);
if (numDescriptors < 0) {
printk(KERN_ERR "%s: dmacHw_calculateDescriptorCount failed\n",
__func__);
return -EINVAL;
}
/* Check to see if we can reuse the existing descriptor ring, or if we need to allocate */
/* a new one. */
ringBytesRequired = dmacHw_descriptorLen(numDescriptors);
/* printk("ringBytesRequired: %d\n", ringBytesRequired); */
if (ringBytesRequired > devAttr->ring.bytesAllocated) {
/* Make sure that this code path is never taken from interrupt context. */
/* It's OK for an interrupt to initiate a DMA transfer, but the descriptor */
/* allocation needs to have already been done. */
might_sleep();
/* Free the old descriptor ring and allocate a new one. */
dma_free_descriptor_ring(&devAttr->ring);
/* And allocate a new one. */
rc =
dma_alloc_descriptor_ring(&devAttr->ring,
numDescriptors);
if (rc < 0) {
printk(KERN_ERR
"%s: dma_alloc_descriptor_ring(%d) failed\n",
__func__, numDescriptors);
return rc;
}
/* Setup the descriptor for this transfer */
if (dmacHw_initDescriptor(devAttr->ring.virtAddr,
devAttr->ring.physAddr,
devAttr->ring.bytesAllocated,
numDescriptors) < 0) {
printk(KERN_ERR "%s: dmacHw_initDescriptor failed\n",
__func__);
return -EINVAL;
}
} else {
/* We've already got enough ring buffer allocated. All we need to do is reset */
/* any control information, just in case the previous DMA was stopped. */
dmacHw_resetDescriptorControl(devAttr->ring.virtAddr);
}
/* dma_alloc/free both set the prevSrc/DstData to 0. If they happen to be the same */
/* as last time, then we don't need to call setDataDescriptor again. */
if (dmacHw_setDataDescriptor(&devAttr->config,
devAttr->ring.virtAddr,
(void *)srcData,
(void *)dstData, numBytes) < 0) {
printk(KERN_ERR "%s: dmacHw_setDataDescriptor failed\n",
__func__);
return -EINVAL;
}
/* Remember the critical information for this transfer so that we can eliminate */
/* another call to dma_alloc_descriptors if the caller reuses the same buffers */
devAttr->prevSrcData = srcData;
devAttr->prevDstData = dstData;
devAttr->prevNumBytes = numBytes;
return 0;
}