dmaengine: sh: rz-dmac: Add device_synchronize callback

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>
Reviewed-by: Geert Uytterhoeven <geert+renesas@glider.be>
Link: https://lore.kernel.org/r/20220722084430.969333-1-biju.das.jz@bp.renesas.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>

diff --git a/drivers/dma/sh/rz-dmac.c b/drivers/dma/sh/rz-dmac.c
index ee2872e..476847a 100644 (file)
--- 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);