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Subject[PATCH RFC v3 03/14] dmaengine: add new dma device registration
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Date
Add a new device registration call in order to allow dynamic registration
of channels. __dma_async_device_register() will only register the DMA
device. The channel registration is done separately.

Signed-off-by: Dave Jiang <dave.jiang@intel.com>
---
drivers/dma/dmaengine.c | 106 ++++++++++++++++++++++++++++-------------------
1 file changed, 63 insertions(+), 43 deletions(-)

diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index a20ab568b637..3c74402f1c34 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c
@@ -149,10 +149,8 @@ static void chan_dev_release(struct device *dev)
struct dma_chan_dev *chan_dev;

chan_dev = container_of(dev, typeof(*chan_dev), device);
- if (atomic_dec_and_test(chan_dev->idr_ref)) {
- ida_free(&dma_ida, chan_dev->dev_id);
+ if (atomic_dec_and_test(chan_dev->idr_ref))
kfree(chan_dev->idr_ref);
- }
kfree(chan_dev);
}

@@ -950,8 +948,23 @@ static int __dma_async_device_channel_register(struct dma_device *device,
chan->client_count = 0;
device->chancnt = chan->chan_id + 1;

+ if (dmaengine_ref_count &&
+ !dma_has_cap(DMA_PRIVATE, device->cap_mask)) {
+ if (dma_chan_get(chan) == -ENODEV) {
+ /*
+ * Note we can only get here for the first
+ * channel as the remaining channels are
+ * guaranteed to get a reference.
+ */
+ rc = -ENODEV;
+ goto chan_get_err;
+ }
+ }
+
return 0;

+ chan_get_err:
+ device_unregister(&chan->dev->device);
err_out:
free_percpu(chan->local);
kfree(chan->dev);
@@ -981,6 +994,8 @@ static void __dma_async_device_channel_unregister(struct dma_device *device,
"%s called while %d clients hold a reference\n",
__func__, chan->client_count);
mutex_lock(&dma_list_mutex);
+ list_del(&chan->device_node);
+ device->chancnt--;
chan->dev->chan = NULL;
mutex_unlock(&dma_list_mutex);
device_unregister(&chan->dev->device);
@@ -995,13 +1010,53 @@ void dma_async_device_channel_unregister(struct dma_device *device,
}
EXPORT_SYMBOL_GPL(dma_async_device_channel_unregister);

+/**
+ * __dma_async_device_register - registers DMA devices found.
+ * Core function that registers a DMA device.
+ * @device: &dma_device
+ */
+static int __dma_async_device_register(struct dma_device *device)
+{
+ struct dma_chan *chan;
+ int rc, i = 0;
+
+ if (!device)
+ return -ENODEV;
+
+ /* Validate device routines */
+ if (!device->dev) {
+ pr_err("DMA device must have valid dev\n");
+ return -EIO;
+ }
+
+ rc = get_dma_id(device);
+ if (rc != 0)
+ return rc;
+
+ /* represent channels in sysfs. Probably want devs too */
+ list_for_each_entry(chan, &device->channels, device_node) {
+ rc = __dma_async_device_channel_register(device, chan, i++);
+ if (rc < 0)
+ return rc;
+ }
+
+ mutex_lock(&dma_list_mutex);
+ list_add_tail_rcu(&device->global_node, &dma_device_list);
+ if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
+ device->privatecnt++; /* Always private */
+ dma_channel_rebalance();
+ mutex_unlock(&dma_list_mutex);
+
+ return 0;
+}
+
/**
* dma_async_device_register - registers DMA devices found
* @device: &dma_device
*/
int dma_async_device_register(struct dma_device *device)
{
- int rc, i = 0;
+ int rc;
struct dma_chan* chan;

if (!device)
@@ -1094,45 +1149,9 @@ int dma_async_device_register(struct dma_device *device)
if (device_has_all_tx_types(device))
dma_cap_set(DMA_ASYNC_TX, device->cap_mask);

- rc = get_dma_id(device);
+ rc = __dma_async_device_register(device);
if (rc != 0)
- return rc;
-
- /* represent channels in sysfs. Probably want devs too */
- list_for_each_entry(chan, &device->channels, device_node) {
- rc = __dma_async_device_channel_register(device, chan, i++);
- if (rc < 0)
- goto err_out;
- }
-
- if (!device->chancnt) {
- dev_err(device->dev, "%s: device has no channels!\n", __func__);
- rc = -ENODEV;
goto err_out;
- }
-
- mutex_lock(&dma_list_mutex);
- /* take references on public channels */
- if (dmaengine_ref_count && !dma_has_cap(DMA_PRIVATE, device->cap_mask))
- list_for_each_entry(chan, &device->channels, device_node) {
- /* if clients are already waiting for channels we need
- * to take references on their behalf
- */
- if (dma_chan_get(chan) == -ENODEV) {
- /* note we can only get here for the first
- * channel as the remaining channels are
- * guaranteed to get a reference
- */
- rc = -ENODEV;
- mutex_unlock(&dma_list_mutex);
- goto err_out;
- }
- }
- list_add_tail_rcu(&device->global_node, &dma_device_list);
- if (dma_has_cap(DMA_PRIVATE, device->cap_mask))
- device->privatecnt++; /* Always private */
- dma_channel_rebalance();
- mutex_unlock(&dma_list_mutex);

return 0;

@@ -1165,15 +1184,16 @@ EXPORT_SYMBOL(dma_async_device_register);
*/
void dma_async_device_unregister(struct dma_device *device)
{
- struct dma_chan *chan;
+ struct dma_chan *chan, *n;

mutex_lock(&dma_list_mutex);
list_del_rcu(&device->global_node);
dma_channel_rebalance();
mutex_unlock(&dma_list_mutex);

- list_for_each_entry(chan, &device->channels, device_node)
+ list_for_each_entry_safe(chan, n, &device->channels, device_node)
__dma_async_device_channel_unregister(device, chan);
+ ida_free(&dma_ida, device->dev_id);
}
EXPORT_SYMBOL(dma_async_device_unregister);

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