/**
* dma_chan_get - try to grab a dma channel's parent driver module
* @chan - channel to grab
*
* Must be called under dma_list_mutex
*/
static int dma_chan_get(struct dma_chan *chan)
{
int err = -ENODEV;
struct module *owner = dma_chan_to_owner(chan);
if (chan->client_count) {
__module_get(owner);
err = 0;
} else if (try_module_get(owner))
err = 0;
if (err == 0)
chan->client_count++;
/* allocate upon first client reference */
if (chan->client_count == 1 && err == 0) {
int desc_cnt = chan->device->device_alloc_chan_resources(chan);
if (desc_cnt < 0) {
err = desc_cnt;
chan->client_count = 0;
module_put(owner);
} else if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
balance_ref_count(chan);
}
return err;
}
/**
* dma_chan_get - try to grab a dma channel's parent driver module
* @chan - channel to grab
*
* Must be called under dma_list_mutex
*/
static int dma_chan_get(struct dma_chan *chan)
{
struct module *owner = dma_chan_to_owner(chan);
int ret;
/* The channel is already in use, update client count */
if (chan->client_count) {
__module_get(owner);
goto out;
}
if (!try_module_get(owner))
return -ENODEV;
/* allocate upon first client reference */
if (chan->device->device_alloc_chan_resources) {
ret = chan->device->device_alloc_chan_resources(chan);
if (ret < 0)
goto err_out;
}
if (!dma_has_cap(DMA_PRIVATE, chan->device->cap_mask))
balance_ref_count(chan);
out:
chan->client_count++;
return 0;
err_out:
module_put(owner);
return ret;
}
/**
* dma_chan_put - drop a reference to a dma channel's parent driver module
* @chan - channel to release
*
* Must be called under dma_list_mutex
*/
static void dma_chan_put(struct dma_chan *chan)
{
if (!chan->client_count)
return; /* this channel failed alloc_chan_resources */
chan->client_count--;
module_put(dma_chan_to_owner(chan));
if (chan->client_count == 0)
chan->device->device_free_chan_resources(chan);
}
/**
* balance_ref_count - catch up the channel reference count
* @chan - channel to balance ->client_count versus dmaengine_ref_count
*
* balance_ref_count must be called under dma_list_mutex
*/
static void balance_ref_count(struct dma_chan *chan)
{
struct module *owner = dma_chan_to_owner(chan);
while (chan->client_count < dmaengine_ref_count) {
__module_get(owner);
chan->client_count++;
}
}
/**
* dma_chan_put - drop a reference to a dma channel's parent driver module
* @chan - channel to release
*
* Must be called under dma_list_mutex
*/
static void dma_chan_put(struct dma_chan *chan)
{
/* This channel is not in use, bail out */
if (!chan->client_count)
return;
chan->client_count--;
module_put(dma_chan_to_owner(chan));
/* This channel is not in use anymore, free it */
if (!chan->client_count && chan->device->device_free_chan_resources)
chan->device->device_free_chan_resources(chan);
}
/**
* dma_chan_put - drop a reference to a dma channel's parent driver module
* @chan - channel to release
*
* Must be called under dma_list_mutex
*/
static void dma_chan_put(struct dma_chan *chan)
{
/* This channel is not in use, bail out */
if (!chan->client_count)
return;
chan->client_count--;
module_put(dma_chan_to_owner(chan));
/* This channel is not in use anymore, free it */
if (!chan->client_count && chan->device->device_free_chan_resources)
chan->device->device_free_chan_resources(chan);
/* If the channel is used via a DMA request router, free the mapping */
if (chan->router && chan->router->route_free) {
chan->router->route_free(chan->router->dev, chan->route_data);
chan->router = NULL;
chan->route_data = NULL;
}
}
/**
* dma_chan_put - drop a reference to a dma channel's parent driver module
* @chan - channel to release
*
* Must be called under dma_list_mutex
*/
static void dma_chan_put(struct dma_chan *chan)
{
/* This channel is not in use, bail out */
if (!chan->client_count)
return;
chan->client_count--;
module_put(dma_chan_to_owner(chan));
/* This channel is not in use anymore, free it */
if (!chan->client_count && chan->device->device_free_chan_resources) {
/* Make sure all operations have completed */
dmaengine_synchronize(chan);
chan->device->device_free_chan_resources(chan);
}
/* If the channel is used via a DMA request router, free the mapping */
if (chan->router && chan->router->route_free) {
chan->router->route_free(chan->router->dev, chan->route_data);
chan->router = NULL;
chan->route_data = NULL;
}
}
