dmatest: convert to dma_request_channel

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>
Reviewed-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Williams <dan.j.williams@intel.com>

diff --git a/drivers/dma/dmatest.c b/drivers/dma/dmatest.c
index db40508..1d6e48f 100644 (file)
--- 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 +360,57 @@ static enum dma_state_client dmatest_add_channel(struct dma_chan *chan)
        list_add_tail(&dtc->node, &dmatest_channels);
        nr_channels++;
 
-       return DMA_ACK;
+       return 0;
 }
 
-static enum dma_state_client dmatest_remove_channel(struct dma_chan *chan)
+static enum dma_state_client filter(struct dma_chan *chan, void *param)
 {
-       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;
-}
-
-/*
- * 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)
-{
-       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;
+       int err = 0;
+
+       dma_cap_zero(mask);
+       dma_cap_set(DMA_MEMCPY, mask);
+       for (;;) {
+               chan = dma_request_channel(mask, filter, NULL);
+               if (chan) {
+                       err = dmatest_add_channel(chan);
+                       if (err == 0)
+                               continue;
+                       else {
+                               dma_release_channel(chan);
+                               break; /* add_channel failed, punt */
+                       }
+               } else
+                       break; /* no more channels available */
+               if (max_channels && nr_channels >= max_channels)
+                       break; /* we have all we need */
+       }
 
-       return 0;
+       return err;
 }
-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 (file)
--- 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)