dmaengine: dw-edma: Add per-channel interrupt routing control

DesignWare eDMA can signal completion locally through edma_int[] and
remotely through IMWr/MSI. When channels are delegated to a remote
frontend, the local endpoint side and the remote host side must not both
service the same DONE/ABORT status.

Add channel interrupt routing state and initialize it from the controller
instance configuration. Update the eDMA and HDMA native paths so
linked-list interrupt generation, HDMA non-linked-list interrupt enables,
and DONE/ABORT masking follow the selected mode. For HDMA native
non-linked-list channels, keep the local stop/abort enables set so status
is latched. In remote mode, also enable remote signaling and mask the local
interrupt pins.

Keep the existing dw-edma-pcie host-side instances in remote interrupt
routing mode so their IMWr/MSI completion model remains unchanged after
local routing becomes the zero value.

Note:
- The routing mode describes where a channel should report completion.
  It does not by itself say whether this dw-edma instance owns the
  interrupt status. A local instance must ignore remote-only channels,
  and a remote instance must ignore local-only channels, even if such
  interrupts are unexpectedly delivered. Otherwise the non-owner side
  could steal the interrupt from the owner by clearing shared DONE/ABORT
  status.

Cc: Devendra K Verma <devendra.verma@amd.com>
Suggested-by: Frank Li <Frank.Li@nxp.com>
Signed-off-by: Koichiro Den <den@valinux.co.jp>
Link: https://patch.msgid.link/20260721062815.4117887-3-den@valinux.co.jp
Signed-off-by: Vinod Koul <vkoul@kernel.org>

1 files changed, 32 insertions, 0 deletions

diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
index da7a5cc93ad4..17cbe7ce55aa 100644
--- a/include/linux/dma/edma.h
+++ b/include/linux/dma/edma.h
@@ -63,6 +63,38 @@ enum dw_edma_chip_flags {
 };
 
 /**
+ * enum dw_edma_ch_irq_mode - per-channel interrupt routing control
+ * @DW_EDMA_CH_IRQ_LOCAL:     local interrupt only (edma_int[])
+ * @DW_EDMA_CH_IRQ_REMOTE:    remote interrupt only (IMWr/MSI), without
+ *                            delivering local edma_int[].
+ *
+ * DesignWare EP eDMA can signal interrupts locally through the edma_int[]
+ * bus, and remotely using posted memory writes (IMWr) that may be
+ * interpreted as MSI/MSI-X by the RC.
+ *
+ * For the v0 eDMA linked-list programming path, DMA_*_INT_MASK gates the local
+ * edma_int[] assertion, while there is no dedicated per-channel mask for IMWr
+ * generation. To request a remote-only interrupt, Synopsys recommends setting
+ * both LIE and RIE, and masking the local interrupt in DMA_*_INT_MASK. See the
+ * DesignWare endpoint databook 6.30a, Linked List Mode interrupt handling
+ * ("Software Programming of an Endpoint's LIE and RIE Bits for Linked List
+ * Transfers", Attention).
+ *
+ * A local (DW_EDMA_CHIP_LOCAL) instance never issues transfers on a
+ * remote-routed channel: REMOTE routing on such an instance denotes a channel
+ * handed over to and driven by the remote side, and the recipe above is
+ * applied by the driving instance.
+ *
+ * HDMA linked-list watermark interrupts have the same LWIE/RWIE guidance. HDMA
+ * non-linked-list mode has dedicated local and remote stop/abort interrupt
+ * enables.
+ */
+enum dw_edma_ch_irq_mode {
+	DW_EDMA_CH_IRQ_LOCAL	= 0,
+	DW_EDMA_CH_IRQ_REMOTE,
+};
+
+/**
  * struct dw_edma_chip - representation of DesignWare eDMA controller hardware
  * @dev:		 struct device of the eDMA controller
  * @nr_irqs:		 total number of DMA IRQs