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Subject[PATCH 08/13] dmatest: convert to dma_request_channel
Date
Replace the client registration infrastructure with a custom loop to
poll for channels. Once dma_request_channel returns NULL stop asking
for channels. A userspace side effect of this change if that loading
the dmatest module before loading a dma driver will result in no
channels being found, previously dmatest would get a callback. To
facilitate testing in the built-in case dmatest_init is marked as a
late_initcall. Another side effect is that channels under test can not
be used for any other purpose.

Cc: Haavard Skinnemoen <haavard.skinnemoen@atmel.com>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>
---
drivers/dma/dmatest.c | 109 ++++++++++++++++-----------------------------
include/linux/dmaengine.h | 6 ++
2 files changed, 44 insertions(+), 71 deletions(-)
diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index db40508..2a7724d 100644
--- a/drivers/dma/dmatest.c
+++ b/drivers/dma/dmatest.c
@@ -35,7 +35,7 @@ MODULE_PARM_DESC(threads_per_chan,

static unsigned int max_channels;
module_param(max_channels, uint, S_IRUGO);
-MODULE_PARM_DESC(nr_channels,
+MODULE_PARM_DESC(max_channels,
"Maximum number of channels to use (default: all)");

/*
@@ -71,7 +71,7 @@ struct dmatest_chan {

/*
* These are protected by dma_list_mutex since they're only used by
- * the DMA client event callback
+ * the DMA filter function callback
*/
static LIST_HEAD(dmatest_channels);
static unsigned int nr_channels;
@@ -317,21 +317,16 @@ static void dmatest_cleanup_channel(struct dmatest_chan *dtc)
kfree(dtc);
}

-static enum dma_state_client dmatest_add_channel(struct dma_chan *chan)
+static int dmatest_add_channel(struct dma_chan *chan)
{
struct dmatest_chan *dtc;
struct dmatest_thread *thread;
unsigned int i;

- /* Have we already been told about this channel? */
- list_for_each_entry(dtc, &dmatest_channels, node)
- if (dtc->chan == chan)
- return DMA_DUP;
-
dtc = kmalloc(sizeof(struct dmatest_chan), GFP_KERNEL);
if (!dtc) {
pr_warning("dmatest: No memory for %s\n", dev_name(&chan->dev));
- return DMA_NAK;
+ return -ENOMEM;
}

dtc->chan = chan;
@@ -365,81 +360,53 @@ static enum dma_state_client dmatest_add_channel(struct dma_chan *chan)
list_add_tail(&dtc->node, &dmatest_channels);
nr_channels++;

- return DMA_ACK;
-}
-
-static enum dma_state_client dmatest_remove_channel(struct dma_chan *chan)
-{
- struct dmatest_chan *dtc, *_dtc;
-
- list_for_each_entry_safe(dtc, _dtc, &dmatest_channels, node) {
- if (dtc->chan == chan) {
- list_del(&dtc->node);
- dmatest_cleanup_channel(dtc);
- pr_debug("dmatest: lost channel %s\n",
- dev_name(&chan->dev));
- return DMA_ACK;
- }
- }
-
- return DMA_DUP;
+ return 0;
}

-/*
- * Start testing threads as new channels are assigned to us, and kill
- * them when the channels go away.
- *
- * When we unregister the client, all channels are removed so this
- * will also take care of cleaning things up when the module is
- * unloaded.
- */
-static enum dma_state_client
-dmatest_event(struct dma_client *client, struct dma_chan *chan,
- enum dma_state state)
+static enum dma_state_client filter(struct dma_chan *chan, void *param)
{
- enum dma_state_client ack = DMA_NAK;
-
- switch (state) {
- case DMA_RESOURCE_AVAILABLE:
- if (!dmatest_match_channel(chan)
- || !dmatest_match_device(chan->device))
- ack = DMA_DUP;
- else if (max_channels && nr_channels >= max_channels)
- ack = DMA_NAK;
- else
- ack = dmatest_add_channel(chan);
- break;
-
- case DMA_RESOURCE_REMOVED:
- ack = dmatest_remove_channel(chan);
- break;
-
- default:
- pr_info("dmatest: Unhandled event %u (%s)\n",
- state, dev_name(&chan->dev));
- break;
- }
-
- return ack;
+ if (!dmatest_match_channel(chan) || !dmatest_match_device(chan->device))
+ return DMA_DUP;
+ else
+ return DMA_ACK;
}

-static struct dma_client dmatest_client = {
- .event_callback = dmatest_event,
-};
-
static int __init dmatest_init(void)
{
- dma_cap_set(DMA_MEMCPY, dmatest_client.cap_mask);
- dma_async_client_register(&dmatest_client);
- dma_async_client_chan_request(&dmatest_client);
+ dma_cap_mask_t mask;
+ struct dma_chan *chan;
+
+ dma_cap_zero(mask);
+ dma_cap_set(DMA_MEMCPY, mask);
+ for (;;) {
+ chan = dma_request_channel(mask, filter, NULL);
+ if (chan) {
+ if (dmatest_add_channel(chan) == 0)
+ continue;
+ else
+ dma_release_channel(chan);
+ } else
+ break; /* no more channels available */
+ if (max_channels && nr_channels >= max_channels)
+ break; /* we have all we need */
+ }

return 0;
}
-module_init(dmatest_init);
+/* when compiled-in wait for drivers to load first */
+late_initcall(dmatest_init);

static void __exit dmatest_exit(void)
{
- dma_async_client_unregister(&dmatest_client);
+ struct dmatest_chan *dtc, *_dtc;
+
+ list_for_each_entry_safe(dtc, _dtc, &dmatest_channels, node) {
+ list_del(&dtc->node);
+ dmatest_cleanup_channel(dtc);
+ pr_debug("dmatest: dropped channel %s\n",
+ dev_name(&dtc->chan->dev));
+ dma_release_channel(dtc->chan);
+ }
}
module_exit(dmatest_exit);

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index fe40bc0..6f2d070 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -400,6 +400,12 @@ __dma_cap_set(enum dma_transaction_type tx_type, dma_cap_mask_t *dstp)
set_bit(tx_type, dstp->bits);
}

+#define dma_cap_zero(mask) __dma_cap_zero(&(mask))
+static inline void __dma_cap_zero(dma_cap_mask_t *dstp)
+{
+ bitmap_zero(dstp->bits, DMA_TX_TYPE_END);
+}
+
#define dma_has_cap(tx, mask) __dma_has_cap((tx), &(mask))
static inline int
__dma_has_cap(enum dma_transaction_type tx_type, dma_cap_mask_t *srcp)


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