[PATCH v6 4/9] dmaengine: Introduce DMA-device device_caps callback
From: Serge Semin <hidden>
Date: 2020-06-17 23:40:52
Also in:
dmaengine, linux-mips, lkml
Subsystem:
dma generic offload engine subsystem, the rest · Maintainers:
Vinod Koul, Linus Torvalds
There are DMA devices (like ours version of Synopsys DW DMAC) which have DMA capabilities non-uniformly redistributed between the device channels. In order to provide a way of exposing the channel-specific parameters to the DMA engine consumers, we introduce a new DMA-device callback. In case if provided it gets called from the dma_get_slave_caps() method and is able to override the generic DMA-device capabilities. Signed-off-by: Serge Semin <redacted> Reviewed-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Alexey Malahov <redacted> Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Andy Shevchenko <andriy.shevchenko@linux.intel.com> Cc: Rob Herring <robh+dt@kernel.org> Cc: linux-mips@vger.kernel.org Cc: devicetree@vger.kernel.org --- Changelog v3: - This is a new patch created as a result of the discussion with Vinod and Andy in the framework of DW DMA burst and LLP capabilities. Changelog v5: - Add in-line comment at the point of the device_caps callback invocation. - Add doc-comment for the device_caps member of struct dma_device. --- drivers/dma/dmaengine.c | 10 ++++++++++ include/linux/dmaengine.h | 4 ++++ 2 files changed, 14 insertions(+)
diff --git a/drivers/dma/dmaengine.c b/drivers/dma/dmaengine.c
index b332ffe52780..7d6ac0ca2af5 100644
--- a/drivers/dma/dmaengine.c
+++ b/drivers/dma/dmaengine.c@@ -598,6 +598,16 @@ int dma_get_slave_caps(struct dma_chan *chan, struct dma_slave_caps *caps) caps->cmd_resume = !!device->device_resume; caps->cmd_terminate = !!device->device_terminate_all; + /* + * DMA engine device might be configured with non-uniformly + * distributed slave capabilities per device channels. In this + * case the corresponding driver may provide the device_caps + * callback to override the generic capabilities with + * channel-specific ones. + */ + if (device->device_caps) + device->device_caps(chan, caps); + return 0; } EXPORT_SYMBOL_GPL(dma_get_slave_caps);
diff --git a/include/linux/dmaengine.h b/include/linux/dmaengine.h
index 0c7403b27133..7ae0daafda82 100644
--- a/include/linux/dmaengine.h
+++ b/include/linux/dmaengine.h@@ -792,6 +792,8 @@ struct dma_filter { * be called after period_len bytes have been transferred. * @device_prep_interleaved_dma: Transfer expression in a generic way. * @device_prep_dma_imm_data: DMA's 8 byte immediate data to the dst address + * @device_caps: May be used to override the generic DMA slave capabilities + * with per-channel specific ones * @device_config: Pushes a new configuration to a channel, return 0 or an error * code * @device_pause: Pauses any transfer happening on a channel. Returns
@@ -891,6 +893,8 @@ struct dma_device { struct dma_chan *chan, dma_addr_t dst, u64 data, unsigned long flags); + void (*device_caps)(struct dma_chan *chan, + struct dma_slave_caps *caps); int (*device_config)(struct dma_chan *chan, struct dma_slave_config *config); int (*device_pause)(struct dma_chan *chan);
--
2.26.2