[RFC] dmaengine: Add metadat_ops for dma_async_tx_descriptor

[Peter Ujfalusi]

If the DMA supports per descriptor metadata it can implement the attach,
get_ptr/set_len callbacks.

Client drivers must only use either attach or get_ptr/set_len to avoid
miss configuration.

Wrappers are also added for the metadata_ops:
dmaengine_desc_attach_metadata()
dmaengine_desc_get_metadata_ptr()
dmaengine_desc_set_metadata_len()

Signed-off-by: Peter Ujfalusi <peter.ujfal...@ti.com>
---
Hi,

since attachments are bouncing back, I send the patch separately

Regards,
Peter

 include/linux/dmaengine.h | 50 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 50 insertions(+)

diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 51fbb861e84b..ac42ace36aa3 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h
@@ -491,6 +491,18 @@ struct dmaengine_unmap_data {
        dma_addr_t addr[0];
 };
 
+struct dma_async_tx_descriptor;
+
+struct dma_descriptor_metadata_ops {
+       int (*attach)(struct dma_async_tx_descriptor *desc, void *data,
+                     size_t len);
+
+       void *(*get_ptr)(struct dma_async_tx_descriptor *desc,
+                        size_t *payload_len, size_t *max_len);
+       int (*set_len)(struct dma_async_tx_descriptor *desc,
+                      size_t payload_len);
+};
+
 /**
  * struct dma_async_tx_descriptor - async transaction descriptor
  * ---dma generic offload fields---
@@ -520,6 +532,7 @@ struct dma_async_tx_descriptor {
        dma_async_tx_callback_result callback_result;
        void *callback_param;
        struct dmaengine_unmap_data *unmap;
+       struct dma_descriptor_metadata_ops *metadata_ops;
 #ifdef CONFIG_ASYNC_TX_ENABLE_CHANNEL_SWITCH
        struct dma_async_tx_descriptor *next;
        struct dma_async_tx_descriptor *parent;
@@ -932,6 +945,43 @@ static inline struct dma_async_tx_descriptor 
*dmaengine_prep_dma_memcpy(
                                                    len, flags);
 }
 
+static inline int dmaengine_desc_attach_metadata(
+               struct dma_async_tx_descriptor *desc, void *data, size_t len)
+{
+       if (!desc)
+               return 0;
+
+       if (!desc->metadata_ops || !desc->metadata_ops->attach)
+               return -ENOTSUPP;
+
+       return desc->metadata_ops->attach(desc, data, len);
+}
+
+static inline void *dmaengine_desc_get_metadata_ptr(
+               struct dma_async_tx_descriptor *desc, size_t *payload_len,
+               size_t *max_len)
+{
+       if (!desc)
+               return NULL;
+
+       if (!desc->metadata_ops || !desc->metadata_ops->get_ptr)
+               return ERR_PTR(-ENOTSUPP);
+
+       return desc->metadata_ops->get_ptr(desc, payload_len, max_len);
+}
+
+static inline int dmaengine_desc_set_metadata_len(
+               struct dma_async_tx_descriptor *desc, size_t payload_len)
+{
+       if (!desc)
+               return 0;
+
+       if (!desc->metadata_ops || !desc->metadata_ops->set_len)
+               return -ENOTSUPP;
+
+       return desc->metadata_ops->set_len(desc, payload_len);
+}
+
 /**
  * dmaengine_terminate_all() - Terminate all active DMA transfers
  * @chan: The channel for which to terminate the transfers
-- 
Peter

Texas Instruments Finland Oy, Porkkalankatu 22, 00180 Helsinki.
Y-tunnus/Business ID: 0615521-4. Kotipaikka/Domicile: Helsinki