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Subject[RFC] dmaengine: Add metadat_ops for dma_async_tx_descriptor
Date
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.ujfalusi@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

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