[PATCH v4] dmaengine: sh: rz-dmac: Add device_synchronize callback

[PATCH v4] dmaengine: sh: rz-dmac: Add device_synchronize callback

[Biju Das]

Some on-chip peripheral modules(for eg:- rspi) on RZ/G2L SoC
use the same signal for both interrupt and DMA transfer requests.
The signal works as a DMA transfer request signal by setting
DMARS, and subsequent interrupt requests to the interrupt controller
are masked.

We can re-enable the interrupt by clearing the DMARS.

This patch adds device_synchronize callback for clearing
DMARS and thereby allowing DMA consumers to switch to
interrupt mode.

Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
---
v3->v4:
 * Increased delay_us 10->100us and timeout_us 1ms->100ms.
v2->v3:
 * Fixed commit description
 * Added check if the DMA operation has been completed or terminated,
   and wait (sleep) if needed.
v1->v2:
 * No change
---
 drivers/dma/sh/rz-dmac.c | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c
index ee2872e7d64c..476847a4916b 100644
--- a/drivers/dma/sh/rz-dmac.c
+++ b/drivers/dma/sh/rz-dmac.c
@@ -12,6 +12,7 @@
 #include <linux/dma-mapping.h>
 #include <linux/dmaengine.h>
 #include <linux/interrupt.h>
+#include <linux/iopoll.h>
 #include <linux/list.h>
 #include <linux/module.h>
 #include <linux/of.h>
@@ -630,6 +631,21 @@ static void rz_dmac_virt_desc_free(struct virt_dma_desc *vd)
 	 */
 }
 
+static void rz_dmac_device_synchronize(struct dma_chan *chan)
+{
+	struct rz_dmac_chan *channel = to_rz_dmac_chan(chan);
+	struct rz_dmac *dmac = to_rz_dmac(chan->device);
+	u32 chstat;
+	int ret;
+
+	ret = read_poll_timeout(rz_dmac_ch_readl, chstat, !(chstat & CHSTAT_EN),
+				100, 100000, false, channel, CHSTAT, 1);
+	if (ret < 0)
+		dev_warn(dmac->dev, "DMA Timeout");
+
+	rz_dmac_set_dmars_register(dmac, channel->index, 0);
+}
+
 /*
  * -----------------------------------------------------------------------------
  * IRQ handling
@@ -909,6 +925,7 @@ static int rz_dmac_probe(struct platform_device *pdev)
 	engine->device_config = rz_dmac_config;
 	engine->device_terminate_all = rz_dmac_terminate_all;
 	engine->device_issue_pending = rz_dmac_issue_pending;
+	engine->device_synchronize = rz_dmac_device_synchronize;
 
 	engine->copy_align = DMAENGINE_ALIGN_1_BYTE;
 	dma_set_max_seg_size(engine->dev, U32_MAX);
-- 
2.25.1

Re: [PATCH v4] dmaengine: sh: rz-dmac: Add device_synchronize callback

[Geert Uytterhoeven]

On Fri, Jul 22, 2022 at 10:44 AM Biju Das <biju.das.jz@bp.renesas.com> wrote:
> Some on-chip peripheral modules(for eg:- rspi) on RZ/G2L SoC
> use the same signal for both interrupt and DMA transfer requests.
> The signal works as a DMA transfer request signal by setting
> DMARS, and subsequent interrupt requests to the interrupt controller
> are masked.
>
> We can re-enable the interrupt by clearing the DMARS.
>
> This patch adds device_synchronize callback for clearing
> DMARS and thereby allowing DMA consumers to switch to
> interrupt mode.
>
> Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
> ---
> v3->v4:
>  * Increased delay_us 10->100us and timeout_us 1ms->100ms.

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

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

Re: [PATCH v4] dmaengine: sh: rz-dmac: Add device_synchronize callback

[Vinod Koul]

On 22-07-22, 09:44, Biju Das wrote:
> Some on-chip peripheral modules(for eg:- rspi) on RZ/G2L SoC
> use the same signal for both interrupt and DMA transfer requests.
> The signal works as a DMA transfer request signal by setting
> DMARS, and subsequent interrupt requests to the interrupt controller
> are masked.
> 
> We can re-enable the interrupt by clearing the DMARS.
> 
> This patch adds device_synchronize callback for clearing
> DMARS and thereby allowing DMA consumers to switch to
> interrupt mode.

Applied, thanks

-- 
~Vinod