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Subject[PATCH V2] dma: add common of_dma_slave_xlate()
Date
From: Stephen Warren <swarren@nvidia.com>

mmp_pdma.c implements a custom of_xlate() function that is 95% identical
to what Tegra will need. Create a function to implement the common part,
so everyone doesn't just cut/paste the implementation.

Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Vinod Koul <vinod.koul@intel.com>
Cc: dmaengine@vger.kernel.org
Signed-off-by: Stephen Warren <swarren@nvidia.com>
---
v2: Squashed the conversion of mmp_pdma.c into the patch that added the
common implementation, so it's easier to see the whole conversion in one
go.

This patch is a dependency for a series that reworks many of the Tegra
drivers.

As such, it needs to go into a topic branch on its own, based directly
on 3.13-rc1. If the DMA maintainers ack the patches I'm happy to create
this topic branch myself and send a pull request to the DMA tree. Or the
patches can be applied to a topic branch by the DMA maintainers and I
will merge their topic branch into the Tegra rework branch that I
mentioned.

Note that this patch is independant from the "dma: add channel request
API that supports deferred probe" which I just sent, so it could
(should?) be a different topic branch.
---
drivers/dma/mmp_pdma.c | 39 ++++++++++-----------------------------
drivers/dma/of-dma.c | 43 +++++++++++++++++++++++++++++++++++++++++++
include/linux/of_dma.h | 14 ++++++++++++++
3 files changed, 67 insertions(+), 29 deletions(-)

diff --git a/drivers/dma/mmp_pdma.c b/drivers/dma/mmp_pdma.c
index dcb1e05149a7..9705cedf623d 100644
--- a/drivers/dma/mmp_pdma.c
+++ b/drivers/dma/mmp_pdma.c
@@ -128,6 +128,7 @@ struct mmp_pdma_device {
void __iomem *base;
struct device *dev;
struct dma_device device;
+ struct of_dma_slave_xlate_info xlate_info;
struct mmp_pdma_phy *phy;
spinlock_t phy_lock; /* protect alloc/free phy channels */
};
@@ -889,37 +890,14 @@ static struct of_device_id mmp_pdma_dt_ids[] = {
};
MODULE_DEVICE_TABLE(of, mmp_pdma_dt_ids);

-static struct dma_chan *mmp_pdma_dma_xlate(struct of_phandle_args *dma_spec,
- struct of_dma *ofdma)
+static int mmp_pdma_of_xlate_post_alloc(struct dma_chan *chan,
+ struct of_phandle_args *dma_spec)
{
- struct mmp_pdma_device *d = ofdma->of_dma_data;
- struct dma_chan *chan, *candidate;
-
-retry:
- candidate = NULL;
-
- /* walk the list of channels registered with the current instance and
- * find one that is currently unused */
- list_for_each_entry(chan, &d->device.channels, device_node)
- if (chan->client_count == 0) {
- candidate = chan;
- break;
- }
-
- if (!candidate)
- return NULL;
+ struct mmp_pdma_chan *c = to_mmp_pdma_chan(chan);

- /* dma_get_slave_channel will return NULL if we lost a race between
- * the lookup and the reservation */
- chan = dma_get_slave_channel(candidate);
+ c->drcmr = dma_spec->args[0];

- if (chan) {
- struct mmp_pdma_chan *c = to_mmp_pdma_chan(chan);
- c->drcmr = dma_spec->args[0];
- return chan;
- }
-
- goto retry;
+ return 0;
}

static int mmp_pdma_probe(struct platform_device *op)
@@ -1009,8 +987,11 @@ static int mmp_pdma_probe(struct platform_device *op)

if (op->dev.of_node) {
/* Device-tree DMA controller registration */
+ pdev->xlate_info.device = &pdev->device;
+ pdev->xlate_info.post_alloc = mmp_pdma_of_xlate_post_alloc;
ret = of_dma_controller_register(op->dev.of_node,
- mmp_pdma_dma_xlate, pdev);
+ of_dma_slave_xlate,
+ &pdev->xlate_info);
if (ret < 0) {
dev_err(&op->dev, "of_dma_controller_register failed\n");
return ret;
diff --git a/drivers/dma/of-dma.c b/drivers/dma/of-dma.c
index f68e25c9af3a..d9786a9c8797 100644
--- a/drivers/dma/of-dma.c
+++ b/drivers/dma/of-dma.c
@@ -218,3 +218,46 @@ struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
&dma_spec->args[0]);
}
EXPORT_SYMBOL_GPL(of_dma_simple_xlate);
+
+struct dma_chan *of_dma_slave_xlate(struct of_phandle_args *dma_spec,
+ struct of_dma *ofdma)
+{
+ struct of_dma_slave_xlate_info *info = ofdma->of_dma_data;
+ struct dma_chan *candidate, *chan;
+ int ret;
+
+retry:
+ candidate = NULL;
+
+ /*
+ * walk the list of channels registered with the current instance and
+ * find one that is currently unused
+ */
+ list_for_each_entry(chan, &info->device->channels, device_node)
+ if (chan->client_count == 0) {
+ candidate = chan;
+ break;
+ }
+
+ if (!candidate)
+ return NULL;
+
+ /*
+ * dma_get_slave_channel will return NULL if we lost a race between
+ * the lookup and the reservation
+ */
+ chan = dma_get_slave_channel(candidate);
+ if (!chan)
+ goto retry;
+
+ if (info->post_alloc) {
+ ret = info->post_alloc(chan, dma_spec);
+ if (ret) {
+ dma_release_channel(chan);
+ return NULL;
+ }
+ }
+
+ return chan;
+}
+EXPORT_SYMBOL_GPL(of_dma_slave_xlate);
diff --git a/include/linux/of_dma.h b/include/linux/of_dma.h
index ae36298ba076..fb4187adc68b 100644
--- a/include/linux/of_dma.h
+++ b/include/linux/of_dma.h
@@ -31,6 +31,12 @@ struct of_dma_filter_info {
dma_filter_fn filter_fn;
};

+struct of_dma_slave_xlate_info {
+ struct dma_device *device;
+ int (*post_alloc)(struct dma_chan *chan,
+ struct of_phandle_args *dma_spec);
+};
+
#ifdef CONFIG_OF
extern int of_dma_controller_register(struct device_node *np,
struct dma_chan *(*of_dma_xlate)
@@ -41,6 +47,8 @@ extern struct dma_chan *of_dma_request_slave_channel(struct device_node *np,
const char *name);
extern struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_spec,
struct of_dma *ofdma);
+extern struct dma_chan *of_dma_slave_xlate(struct of_phandle_args *dma_spec,
+ struct of_dma *ofdma);
#else
static inline int of_dma_controller_register(struct device_node *np,
struct dma_chan *(*of_dma_xlate)
@@ -66,6 +74,12 @@ static inline struct dma_chan *of_dma_simple_xlate(struct of_phandle_args *dma_s
return NULL;
}

+static inline struct dma_chan *of_dma_slave_xlate(struct of_phandle_args *dma_spec,
+ struct of_dma *ofdma)
+{
+ return NULL;
+}
+
#endif

#endif /* __LINUX_OF_DMA_H */
--
1.8.1.5


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