4 files changed, 95 insertions, 28 deletions

diff --git a/drivers/dma/sh/shdma-base.c b/drivers/dma/sh/shdma-base.c
index 73db282a1436..27f5c781fd73 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 9a10d8bbdef2..027c9be97654 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 4e83f3e034f3..b64d6bec6f90 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 6263ad2e7426..93f9821554b6 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);