dma: sh: provide a migration path for slave drivers to stop using .private

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@gmx.de>
[applied a trvial checkpath fix]
Signed-off-by: Vinod Koul <vinod.koul@linux.intel.com>

diff --git a/drivers/dma/sh/shdma-base.c b/drivers/dma/sh/shdma-base.c
index 73db282a14362dbd7fa8d2782fa70c8cfdfa11cf..27f5c781fd73fa2b1de7d96fa189eada935c0467 100644 (file)
--- 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 9a10d8bbdef236f77174830d9ede7520951d01d4..027c9be976544edc7029431e04e5f9b8697503ed 100644 (file)
--- 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 4e83f3e034f3873d531580550a1940b4b49f6461..b64d6bec6f903637617f06f153547295336d4133 100644 (file)
--- 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 6263ad2e7426570ddf21f88b031aa6c2498a96e3..93f9821554b6792adc3a2a435de89449c3b0e3ef 100644 (file)
--- 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);