On Sat, Feb 07, 2026 at 02:26:40AM +0900, Koichiro Den wrote:
> Endpoint controller drivers may need to expose or consume eDMA-related
> resources (e.g. for remote programming or doorbell/self-tests). For
> that, consumers need a stable way to discover the Linux IRQ used by a
> given eDMA channel/vector and a register offset suitable for interrupt
> emulation.
>
> Record each channel's IRQ-vector index and store the requested Linux IRQ
> number. Add a core callback .ch_info() to provide core-specific metadata
> and implement it for v0.
>
> Export dw_edma_chan_info() so that platform drivers can retrieve:
> - per-channel device name
> - Linux IRQ number for the channel's interrupt vector
> - offset of the register used as an emulated-interrupt doorbell within
> the eDMA register window.
>
> Signed-off-by: Koichiro Den <[email protected]>
> ---
> drivers/dma/dw-edma/dw-edma-core.c | 31 +++++++++++++++++++++++++++
> drivers/dma/dw-edma/dw-edma-core.h | 14 ++++++++++++
> drivers/dma/dw-edma/dw-edma-v0-core.c | 7 ++++++
> include/linux/dma/edma.h | 20 +++++++++++++++++
> 4 files changed, 72 insertions(+)
>
> diff --git a/drivers/dma/dw-edma/dw-edma-core.c
> b/drivers/dma/dw-edma/dw-edma-core.c
> index dd01a9aa8ad8..147a5466e4e7 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-core.c
> @@ -842,6 +842,7 @@ static int dw_edma_channel_setup(struct dw_edma *dw, u32
> wr_alloc, u32 rd_alloc)
> else
> pos = wr_alloc + chan->id % rd_alloc;
>
> + chan->irq_idx = pos;
> irq = &dw->irq[pos];
>
> if (chan->dir == EDMA_DIR_WRITE)
> @@ -947,6 +948,7 @@ static int dw_edma_irq_request(struct dw_edma *dw,
> if (irq_get_msi_desc(irq))
> get_cached_msi_msg(irq, &dw->irq[0].msi);
>
> + dw->irq[0].irq = irq;
> dw->nr_irqs = 1;
> } else {
> /* Distribute IRQs equally among all channels */
> @@ -973,6 +975,7 @@ static int dw_edma_irq_request(struct dw_edma *dw,
>
> if (irq_get_msi_desc(irq))
> get_cached_msi_msg(irq, &dw->irq[i].msi);
> + dw->irq[i].irq = irq;
> }
>
> dw->nr_irqs = i;
> @@ -1098,6 +1101,34 @@ int dw_edma_remove(struct dw_edma_chip *chip)
> }
> EXPORT_SYMBOL_GPL(dw_edma_remove);
>
> +int dw_edma_chan_info(struct dw_edma_chip *chip, unsigned int ch_idx,
> + struct dw_edma_chan_info *info)
> +{
> + struct dw_edma *dw = chip->dw;
> + struct dw_edma_chan *chan;
> + struct dma_chan *dchan;
> + u32 ch_cnt;
> + int ret;
> +
> + if (!chip || !info || !dw)
> + return -EINVAL;
> +
> + ch_cnt = dw->wr_ch_cnt + dw->rd_ch_cnt;
> + if (ch_idx >= ch_cnt)
> + return -EINVAL;
> +
> + chan = &dw->chan[ch_idx];
> + dchan = &chan->vc.chan;
> +
> + ret = dw_edma_core_ch_info(dw, chan, info);
> + if (ret)
> + return ret;
> +
> + info->irq = dw->irq[chan->irq_idx].irq;
> + return 0;
> +}
> +EXPORT_SYMBOL_GPL(dw_edma_chan_info);
> +
> MODULE_LICENSE("GPL v2");
> MODULE_DESCRIPTION("Synopsys DesignWare eDMA controller core driver");
> MODULE_AUTHOR("Gustavo Pimentel <[email protected]>");
> diff --git a/drivers/dma/dw-edma/dw-edma-core.h
> b/drivers/dma/dw-edma/dw-edma-core.h
> index abc97e375484..e92891ed5536 100644
> --- a/drivers/dma/dw-edma/dw-edma-core.h
> +++ b/drivers/dma/dw-edma/dw-edma-core.h
> @@ -82,6 +82,7 @@ struct dw_edma_chan {
> struct msi_msg msi;
>
> enum dw_edma_ch_irq_mode irq_mode;
> + u32 irq_idx;
can we directly save irq_number?
>
> enum dw_edma_request request;
> enum dw_edma_status status;
> @@ -95,6 +96,7 @@ struct dw_edma_irq {
> u32 wr_mask;
> u32 rd_mask;
> struct dw_edma *dw;
> + int irq;
> };
>
> struct dw_edma {
> @@ -129,6 +131,7 @@ struct dw_edma_core_ops {
> void (*ch_config)(struct dw_edma_chan *chan);
> void (*debugfs_on)(struct dw_edma *dw);
> void (*ack_selfirq)(struct dw_edma *dw);
> + void (*ch_info)(struct dw_edma_chan *chan, struct dw_edma_chan_info
> *info);
> };
>
> struct dw_edma_sg {
> @@ -219,6 +222,17 @@ int dw_edma_core_ack_selfirq(struct dw_edma *dw)
> return 0;
> }
>
> +static inline
> +int dw_edma_core_ch_info(struct dw_edma *dw, struct dw_edma_chan *chan,
> + struct dw_edma_chan_info *info)
wrap int to previous line, check others.
Frank
> +{
> + if (!dw->core->ch_info)
> + return -EOPNOTSUPP;
> +
> + dw->core->ch_info(chan, info);
> + return 0;
> +}
> +
> static inline
> bool dw_edma_core_ch_ignore_irq(struct dw_edma_chan *chan)
> {
> diff --git a/drivers/dma/dw-edma/dw-edma-v0-core.c
> b/drivers/dma/dw-edma/dw-edma-v0-core.c
> index 68e0d088570d..9c7908a76fff 100644
> --- a/drivers/dma/dw-edma/dw-edma-v0-core.c
> +++ b/drivers/dma/dw-edma/dw-edma-v0-core.c
> @@ -529,6 +529,12 @@ static void dw_edma_v0_core_ack_selfirq(struct dw_edma
> *dw)
> SET_BOTH_32(dw, int_clear, 0);
> }
>
> +static void dw_edma_v0_core_ch_info(struct dw_edma_chan *chan,
> + struct dw_edma_chan_info *info)
> +{
> + info->db_offset = offsetof(struct dw_edma_v0_regs, rd_int_status);
> +}
> +
> static const struct dw_edma_core_ops dw_edma_v0_core = {
> .off = dw_edma_v0_core_off,
> .ch_count = dw_edma_v0_core_ch_count,
> @@ -538,6 +544,7 @@ static const struct dw_edma_core_ops dw_edma_v0_core = {
> .ch_config = dw_edma_v0_core_ch_config,
> .debugfs_on = dw_edma_v0_core_debugfs_on,
> .ack_selfirq = dw_edma_v0_core_ack_selfirq,
> + .ch_info = dw_edma_v0_core_ch_info,
> };
>
> void dw_edma_v0_core_register(struct dw_edma *dw)
> diff --git a/include/linux/dma/edma.h b/include/linux/dma/edma.h
> index 53b31a974331..9fd78dc313e5 100644
> --- a/include/linux/dma/edma.h
> +++ b/include/linux/dma/edma.h
> @@ -129,10 +129,23 @@ struct dw_edma_chip {
> struct dw_edma *dw;
> };
>
> +/**
> + * struct dw_edma_chan_info - DW eDMA channel metadata
> + * @irq: Linux IRQ number used by this channel's interrupt vector
> + * @db_offset: offset within the eDMA register window that can be used
> as
> + * an interrupt-emulation doorbell for this channel
> + */
> +struct dw_edma_chan_info {
> + int irq;
> + resource_size_t db_offset;
> +};
> +
> /* Export to the platform drivers */
> #if IS_REACHABLE(CONFIG_DW_EDMA)
> int dw_edma_probe(struct dw_edma_chip *chip);
> int dw_edma_remove(struct dw_edma_chip *chip);
> +int dw_edma_chan_info(struct dw_edma_chip *chip, unsigned int ch_idx,
> + struct dw_edma_chan_info *info);
> #else
> static inline int dw_edma_probe(struct dw_edma_chip *chip)
> {
> @@ -143,6 +156,13 @@ static inline int dw_edma_remove(struct dw_edma_chip
> *chip)
> {
> return 0;
> }
> +
> +static inline int dw_edma_chan_info(struct dw_edma_chip *chip,
> + unsigned int ch_idx,
> + struct dw_edma_chan_info *info)
> +{
> + return -ENODEV;
> +}
> #endif /* CONFIG_DW_EDMA */
>
> #endif /* _DW_EDMA_H */
> --
> 2.51.0
>
