[RFC PATCH v4 05/38] dmaengine: dw-edma: Add a helper to query linked-list region
From: Koichiro Den <hidden>
Date: 2026-01-18 13:55:05
Also in:
dmaengine, linux-devicetree, linux-doc, linux-iommu, linux-kselftest, linux-pci, linux-renesas-soc, lkml
Subsystem:
designware edma core ip driver, dma generic offload engine subsystem, the rest · Maintainers:
Manivannan Sadhasivam, Vinod Koul, Linus Torvalds
A remote eDMA provider may need to expose the linked-list (LL) memory region that was configured by platform glue (typically at boot), so the peer (host) can map it and operate the remote view of the controller. Export dw_edma_chan_get_ll_region() to return the LL region associated with a given dma_chan. Signed-off-by: Koichiro Den <redacted> --- drivers/dma/dw-edma/dw-edma-core.c | 26 ++++++++++++++++++++++++++ include/linux/dma/edma.h | 14 ++++++++++++++ 2 files changed, 40 insertions(+)
diff --git a/drivers/dma/dw-edma/dw-edma-core.c b/drivers/dma/dw-edma/dw-edma-core.c
index 0eb8fc1dcc34..c4fb66a9b5f5 100644
--- a/drivers/dma/dw-edma/dw-edma-core.c
+++ b/drivers/dma/dw-edma/dw-edma-core.c@@ -1209,6 +1209,32 @@ int dw_edma_chan_register_notify(struct dma_chan *dchan, } EXPORT_SYMBOL_GPL(dw_edma_chan_register_notify); +int dw_edma_chan_get_ll_region(struct dma_chan *dchan, + struct dw_edma_region *region) +{ + struct dw_edma_chip *chip; + struct dw_edma_chan *chan; + + if (!dchan || !region || !dchan->device) + return -ENODEV; + + chan = dchan2dw_edma_chan(dchan); + if (!chan) + return -ENODEV; + + chip = chan->dw->chip; + if (!(chip->flags & DW_EDMA_CHIP_LOCAL)) + return -EINVAL; + + if (chan->dir == EDMA_DIR_WRITE) + *region = chip->ll_region_wr[chan->id]; + else + *region = chip->ll_region_rd[chan->id]; + + return 0; +} +EXPORT_SYMBOL_GPL(dw_edma_chan_get_ll_region); + MODULE_LICENSE("GPL v2"); MODULE_DESCRIPTION("Synopsys DesignWare eDMA controller core driver"); MODULE_AUTHOR("Gustavo Pimentel <gustavo.pimentel@synopsys.com>");
diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
index 3c538246de07..c9ec426e27ec 100644
--- a/include/linux/dma/edma.h
+++ b/include/linux/dma/edma.h@@ -153,6 +153,14 @@ bool dw_edma_chan_ignore_irq(struct dma_chan *chan); int dw_edma_chan_register_notify(struct dma_chan *chan, void (*cb)(struct dma_chan *chan, void *user), void *user); + +/** + * dw_edma_chan_get_ll_region - get linked list (LL) memory for a dma_chan + * @chan: the target DMA channel + * @region: output parameter returning the corresponding LL region + */ +int dw_edma_chan_get_ll_region(struct dma_chan *chan, + struct dw_edma_region *region); #else static inline int dw_edma_probe(struct dw_edma_chip *chip) {
@@ -182,6 +190,12 @@ static inline int dw_edma_chan_register_notify(struct dma_chan *chan, { return -ENODEV; } + +static inline int dw_edma_chan_get_ll_region(struct dma_chan *chan, + struct dw_edma_region *region) +{ + return -EINVAL; +} #endif /* CONFIG_DW_EDMA */ struct pci_epc;
--
2.51.0