This patch extends the sh dmaengine driver to support the preferred channel
selection and configuration method, instead of using the "private" field
from struct dma_chan. We add a standard filter function to be used by
slave drivers instead of implementing their own ones, and add support for
the DMA_SLAVE_CONFIG control operation, which must accompany the new
channel selection method. We still support the legacy .private channel
allocation method to cater for a smooth driver migration.
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@xxxxxx>
---
drivers/dma/sh/shdma-base.c | 114 +++++++++++++++++++++++++++++++++---------
drivers/dma/sh/shdma.c | 5 +-
include/linux/sh_dma.h | 2 +
include/linux/shdma-base.h | 2 +-
4 files changed, 95 insertions(+), 28 deletions(-)
diff --git a/drivers/dma/sh/shdma-base.c b/drivers/dma/sh/shdma-base.c
index 73db282..0c34c73 100644
--- a/drivers/dma/sh/shdma-base.c
+++ b/drivers/dma/sh/shdma-base.c
@@ -171,6 +171,65 @@ static struct shdma_desc *shdma_get_desc(struct shdma_chan *schan)
return NULL;
}
+static int shdma_setup_slave(struct shdma_chan *schan, int slave_id)
+{
+ struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
+ const struct shdma_ops *ops = sdev->ops;
+ int ret;
+
+ if (slave_id < 0 || slave_id >= slave_num)
+ return -EINVAL;
+
+ if (test_and_set_bit(slave_id, shdma_slave_used))
+ return -EBUSY;
+
+ ret = ops->set_slave(schan, slave_id, false);
+ if (ret < 0) {
+ clear_bit(slave_id, shdma_slave_used);
+ return ret;
+ }
+
+ schan->slave_id = slave_id;
+
+ return 0;
+}
+
+/*
+ * This is the standard shdma filter function to be used as a replacement to the
+ * "old" method, using the .private pointer. If for some reason you allocate a
+ * channel without slave data, use something like ERR_PTR(-EINVAL) as a filter
+ * parameter. If this filter is used, the slave driver, after calling
+ * dma_request_channel(), will also have to call dmaengine_slave_config() with
+ * .slave_id, .direction, and either .src_addr or .dst_addr set.
+ * NOTE: this filter doesn't support multiple DMAC drivers with the DMA_SLAVE
+ * capability! If this becomes a requirement, hardware glue drivers, using this
+ * services would have to provide their own filters, which first would check
+ * the device driver, similar to how other DMAC drivers, e.g., sa11x0-dma.c, do
+ * this, and only then, in case of a match, call this common filter.
+ */
+bool shdma_chan_filter(struct dma_chan *chan, void *arg)
+{
+ struct shdma_chan *schan = to_shdma_chan(chan);
+ struct shdma_dev *sdev = to_shdma_dev(schan->dma_chan.device);
+ const struct shdma_ops *ops = sdev->ops;
+ int slave_id = (int)arg;
+ int ret;
+
+ if (slave_id < 0)
+ /* No slave requested - arbitrary channel */
+ return true;
+
+ if (slave_id >= slave_num)
+ return false;
+
+ ret = ops->set_slave(schan, slave_id, true);
+ if (ret < 0)
+ return false;
+
+ return true;
+}
+EXPORT_SYMBOL(shdma_chan_filter);
+
static int shdma_alloc_chan_resources(struct dma_chan *chan)
{
struct shdma_chan *schan = to_shdma_chan(chan);
@@ -185,21 +244,10 @@ static int shdma_alloc_chan_resources(struct dma_chan *chan)
* never runs concurrently with itself or free_chan_resources.
*/
if (slave) {
- if (slave->slave_id < 0 || slave->slave_id >= slave_num) {
- ret = -EINVAL;
- goto evalid;
- }
-
- if (test_and_set_bit(slave->slave_id, shdma_slave_used)) {
- ret = -EBUSY;
- goto etestused;
- }
-
- ret = ops->set_slave(schan, slave->slave_id);
+ /* Legacy mode: .private is set in filter */
+ ret = shdma_setup_slave(schan, slave->slave_id);
if (ret < 0)
goto esetslave;
-
- schan->slave_id = slave->slave_id;
} else {
schan->slave_id = -EINVAL;
}
@@ -228,8 +276,6 @@ edescalloc:
if (slave)
esetslave:
clear_bit(slave->slave_id, shdma_slave_used);
-etestused:
-evalid:
chan->private = NULL;
return ret;
}
@@ -587,22 +633,40 @@ static int shdma_control(struct dma_chan *chan, enum dma_ctrl_cmd cmd,
struct shdma_chan *schan = to_shdma_chan(chan);
struct shdma_dev *sdev = to_shdma_dev(chan->device);
const struct shdma_ops *ops = sdev->ops;
+ struct dma_slave_config *config;
unsigned long flags;
-
- /* Only supports DMA_TERMINATE_ALL */
- if (cmd != DMA_TERMINATE_ALL)
- return -ENXIO;
+ int ret;
if (!chan)
return -EINVAL;
- spin_lock_irqsave(&schan->chan_lock, flags);
-
- ops->halt_channel(schan);
-
- spin_unlock_irqrestore(&schan->chan_lock, flags);
+ switch (cmd) {
+ case DMA_TERMINATE_ALL:
+ spin_lock_irqsave(&schan->chan_lock, flags);
+ ops->halt_channel(schan);
+ spin_unlock_irqrestore(&schan->chan_lock, flags);
- shdma_chan_ld_cleanup(schan, true);
+ shdma_chan_ld_cleanup(schan, true);
+ break;
+ case DMA_SLAVE_CONFIG:
+ /*
+ * So far only .slave_id is used, but the slave drivers are
+ * encouraged to also set a transfer direction and an address.
+ */
+ if (!arg)
+ return -EINVAL;
+ /*
+ * We could lock this, but you shouldn't be configuring the
+ * channel, while using it...
+ */
+ config = (struct dma_slave_config*)arg;
+ ret = shdma_setup_slave(schan, config->slave_id);
+ if (ret < 0)
+ return ret;
+ break;
+ default:
+ return -ENXIO;
+ }
return 0;
}
diff --git a/drivers/dma/sh/shdma.c b/drivers/dma/sh/shdma.c
index 9a10d8b..027c9be 100644
--- a/drivers/dma/sh/shdma.c
+++ b/drivers/dma/sh/shdma.c
@@ -320,7 +320,7 @@ static const struct sh_dmae_slave_config *dmae_find_slave(
}
static int sh_dmae_set_slave(struct shdma_chan *schan,
- int slave_id)
+ int slave_id, bool try)
{
struct sh_dmae_chan *sh_chan = container_of(schan, struct sh_dmae_chan,
shdma_chan);
@@ -328,7 +328,8 @@ static int sh_dmae_set_slave(struct shdma_chan *schan,
if (!cfg)
return -ENODEV;
- sh_chan->config = cfg;
+ if (!try)
+ sh_chan->config = cfg;
return 0;
}
diff --git a/include/linux/sh_dma.h b/include/linux/sh_dma.h
index 4e83f3e..b64d6be 100644
--- a/include/linux/sh_dma.h
+++ b/include/linux/sh_dma.h
@@ -99,4 +99,6 @@ struct sh_dmae_pdata {
#define CHCR_TE 0x00000002
#define CHCR_IE 0x00000004
+bool shdma_chan_filter(struct dma_chan *chan, void *arg);
+
#endif
diff --git a/include/linux/shdma-base.h b/include/linux/shdma-base.h
index 6263ad2..93f9821 100644
--- a/include/linux/shdma-base.h
+++ b/include/linux/shdma-base.h
@@ -93,7 +93,7 @@ struct shdma_ops {
dma_addr_t (*slave_addr)(struct shdma_chan *);
int (*desc_setup)(struct shdma_chan *, struct shdma_desc *,
dma_addr_t, dma_addr_t, size_t *);
- int (*set_slave)(struct shdma_chan *, int);
+ int (*set_slave)(struct shdma_chan *, int, bool);
void (*setup_xfer)(struct shdma_chan *, int);
void (*start_xfer)(struct shdma_chan *, struct shdma_desc *);
struct shdma_desc *(*embedded_desc)(void *, int);
--
1.7.2.5
--
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