The Renesas RZ/T2H (R9A09G077) and RZ/N2H (R9A09G087) SoCs use a
completely different ICU unit compared to RZ/V2H, which requires a
separate implementation.

To prepare for adding support for these SoCs, add a chip-specific
structure and put a pointer to the rzv2h_icu_register_dma_req() function
in the .register_dma_req field of the chip-specific structure to allow
for other implementations. Do the same for the default request value,
RZV2H_ICU_DMAC_REQ_NO_DEFAULT.

While at it, factor out the logic that calls .register_dma_req() or
rz_dmac_set_dmars_register() into a separate function to remove some
code duplication. Since the default values are different between the
two, use -1 for designating that the default value should be used.

Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@renesas.com>
---

V2:
 * remove notes

 drivers/dma/sh/rz-dmac.c | 68 +++++++++++++++++++++++-----------------
 1 file changed, 39 insertions(+), 29 deletions(-)

diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c
index 20a5c1766a58..f94be3f8e232 100644
--- a/drivers/dma/sh/rz-dmac.c
+++ b/drivers/dma/sh/rz-dmac.c
@@ -95,9 +95,16 @@ struct rz_dmac_icu {
 	u8 dmac_index;
 };
 
+struct rz_dmac_info {
+	void (*register_dma_req)(struct platform_device *icu_dev, u8 dmac_index,
+				 u8 dmac_channel, u16 req_no);
+	u16 dma_req_no_default;
+};
+
 struct rz_dmac {
 	struct dma_device engine;
 	struct rz_dmac_icu icu;
+	const struct rz_dmac_info *info;
 	struct device *dev;
 	struct reset_control *rstc;
 	void __iomem *base;
@@ -106,8 +113,6 @@ struct rz_dmac {
 	unsigned int n_channels;
 	struct rz_dmac_chan *channels;
 
-	bool has_icu;
-
 	DECLARE_BITMAP(modules, 1024);
 };
 
@@ -319,6 +324,19 @@ static void rz_dmac_set_dmars_register(struct rz_dmac *dmac, int nr, u32 dmars)
 	rz_dmac_ext_writel(dmac, dmars32, dmars_offset);
 }
 
+static void rz_dmac_set_dma_req_no(struct rz_dmac *dmac, unsigned int index,
+				   int req_no)
+{
+	if (req_no < 0)
+		req_no = dmac->info->dma_req_no_default;
+
+	if (dmac->info->register_dma_req)
+		dmac->info->register_dma_req(dmac->icu.pdev, dmac->icu.dmac_index,
+					     index, req_no);
+	else
+		rz_dmac_set_dmars_register(dmac, index, req_no);
+}
+
 static void rz_dmac_prepare_desc_for_memcpy(struct rz_dmac_chan *channel)
 {
 	struct dma_chan *chan = &channel->vc.chan;
@@ -336,13 +354,7 @@ static void rz_dmac_prepare_desc_for_memcpy(struct rz_dmac_chan *channel)
 	lmdesc->chext = 0;
 	lmdesc->header = HEADER_LV;
 
-	if (dmac->has_icu) {
-		rzv2h_icu_register_dma_req(dmac->icu.pdev, dmac->icu.dmac_index,
-					   channel->index,
-					   RZV2H_ICU_DMAC_REQ_NO_DEFAULT);
-	} else {
-		rz_dmac_set_dmars_register(dmac, channel->index, 0);
-	}
+	rz_dmac_set_dma_req_no(dmac, channel->index, -1);
 
 	channel->chcfg = chcfg;
 	channel->chctrl = CHCTRL_STG | CHCTRL_SETEN;
@@ -393,12 +405,7 @@ static void rz_dmac_prepare_descs_for_slave_sg(struct rz_dmac_chan *channel)
 
 	channel->lmdesc.tail = lmdesc;
 
-	if (dmac->has_icu) {
-		rzv2h_icu_register_dma_req(dmac->icu.pdev, dmac->icu.dmac_index,
-					   channel->index, channel->mid_rid);
-	} else {
-		rz_dmac_set_dmars_register(dmac, channel->index, channel->mid_rid);
-	}
+	rz_dmac_set_dma_req_no(dmac, channel->index, channel->mid_rid);
 
 	channel->chctrl = CHCTRL_SETEN;
 }
@@ -671,13 +678,7 @@ static void rz_dmac_device_synchronize(struct dma_chan *chan)
 	if (ret < 0)
 		dev_warn(dmac->dev, "DMA Timeout");
 
-	if (dmac->has_icu) {
-		rzv2h_icu_register_dma_req(dmac->icu.pdev, dmac->icu.dmac_index,
-					   channel->index,
-					   RZV2H_ICU_DMAC_REQ_NO_DEFAULT);
-	} else {
-		rz_dmac_set_dmars_register(dmac, channel->index, 0);
-	}
+	rz_dmac_set_dma_req_no(dmac, channel->index, -1);
 }
 
 /*
@@ -868,14 +869,13 @@ static int rz_dmac_parse_of_icu(struct device *dev, struct rz_dmac *dmac)
 	uint32_t dmac_index;
 	int ret;
 
-	ret = of_parse_phandle_with_fixed_args(np, "renesas,icu", 1, 0, &args);
-	if (ret == -ENOENT)
+	if (!dmac->info->register_dma_req)
 		return 0;
+
+	ret = of_parse_phandle_with_fixed_args(np, "renesas,icu", 1, 0, &args);
 	if (ret)
 		return ret;
 
-	dmac->has_icu = true;
-
 	dmac->icu.pdev = of_find_device_by_node(args.np);
 	of_node_put(args.np);
 	if (!dmac->icu.pdev) {
@@ -930,6 +930,7 @@ static int rz_dmac_probe(struct platform_device *pdev)
 	if (!dmac)
 		return -ENOMEM;
 
+	dmac->info = device_get_match_data(&pdev->dev);
 	dmac->dev = &pdev->dev;
 	platform_set_drvdata(pdev, dmac);
 
@@ -947,7 +948,7 @@ static int rz_dmac_probe(struct platform_device *pdev)
 	if (IS_ERR(dmac->base))
 		return PTR_ERR(dmac->base);
 
-	if (!dmac->has_icu) {
+	if (!dmac->info->register_dma_req) {
 		dmac->ext_base = devm_platform_ioremap_resource(pdev, 1);
 		if (IS_ERR(dmac->ext_base))
 			return PTR_ERR(dmac->ext_base);
@@ -1067,9 +1068,18 @@ static void rz_dmac_remove(struct platform_device *pdev)
 	pm_runtime_disable(&pdev->dev);
 }
 
+static const struct rz_dmac_info rz_dmac_v2h_info = {
+	.register_dma_req = rzv2h_icu_register_dma_req,
+	.dma_req_no_default = RZV2H_ICU_DMAC_REQ_NO_DEFAULT,
+};
+
+static const struct rz_dmac_info rz_dmac_common_info = {
+	.dma_req_no_default = 0,
+};
+
 static const struct of_device_id of_rz_dmac_match[] = {
-	{ .compatible = "renesas,r9a09g057-dmac", },
-	{ .compatible = "renesas,rz-dmac", },
+	{ .compatible = "renesas,r9a09g057-dmac", .data = &rz_dmac_v2h_info },
+	{ .compatible = "renesas,rz-dmac", .data = &rz_dmac_common_info },
 	{ /* Sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, of_rz_dmac_match);
-- 
2.52.0

Hi Cosmin,

On Mon, 1 Dec 2025 at 13:52, Cosmin Tanislav
<cosmin-gabriel.tanislav.xa@renesas.com> wrote:
> The Renesas RZ/T2H (R9A09G077) and RZ/N2H (R9A09G087) SoCs use a
> completely different ICU unit compared to RZ/V2H, which requires a
> separate implementation.
>
> To prepare for adding support for these SoCs, add a chip-specific
> structure and put a pointer to the rzv2h_icu_register_dma_req() function
> in the .register_dma_req field of the chip-specific structure to allow
> for other implementations. Do the same for the default request value,
> RZV2H_ICU_DMAC_REQ_NO_DEFAULT.
>
> While at it, factor out the logic that calls .register_dma_req() or
> rz_dmac_set_dmars_register() into a separate function to remove some
> code duplication. Since the default values are different between the
> two, use -1 for designating that the default value should be used.
>
> Signed-off-by: Cosmin Tanislav <cosmin-gabriel.tanislav.xa@renesas.com>

Thanks for your patch!

Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>

You can find a few non-functional nits below...

> --- a/drivers/dma/sh/rz-dmac.c
> +++ b/drivers/dma/sh/rz-dmac.c
> @@ -95,9 +95,16 @@ struct rz_dmac_icu {
>         u8 dmac_index;
>  };
>
> +struct rz_dmac_info {
> +       void (*register_dma_req)(struct platform_device *icu_dev, u8 dmac_index,
> +                                u8 dmac_channel, u16 req_no);

icu_register_dma_req, to make clear this is ICU-specific?

> +       u16 dma_req_no_default;

default_dma_req_no, to avoid confusion between literal "no" and an
abbreviation of "number"?

> +};
> +

> @@ -1067,9 +1068,18 @@ static void rz_dmac_remove(struct platform_device *pdev)
>         pm_runtime_disable(&pdev->dev);
>  }
>
> +static const struct rz_dmac_info rz_dmac_v2h_info = {
> +       .register_dma_req = rzv2h_icu_register_dma_req,
> +       .dma_req_no_default = RZV2H_ICU_DMAC_REQ_NO_DEFAULT,

Since this is the only remaining user of RZV2H_ICU_DMAC_REQ_NO_DEFAULT,
and this structure does specify hardware, perhaps just hardcode 0x3ff?

> +};
> +
> +static const struct rz_dmac_info rz_dmac_common_info = {

rz_dmac_classic_info, as this is not really common to all variants?
I am open for a different name ;-)

> +       .dma_req_no_default = 0,
> +};
> +
>  static const struct of_device_id of_rz_dmac_match[] = {
> -       { .compatible = "renesas,r9a09g057-dmac", },
> -       { .compatible = "renesas,rz-dmac", },
> +       { .compatible = "renesas,r9a09g057-dmac", .data = &rz_dmac_v2h_info },
> +       { .compatible = "renesas,rz-dmac", .data = &rz_dmac_common_info },
>         { /* Sentinel */ }
>  };
>  MODULE_DEVICE_TABLE(of, of_rz_dmac_match);

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds