dmaengine: sh: rz-dmac: Add reset support

Add reset support for DMAC module found on RZ/G2L alike SoCs.

For booting the board, reset release of the DMAC module is required
otherwise we don't get GIC interrupts. Currently the reset release
was done by the bootloader now move this to the driver instead.
Signed-off-by: Biju Das <biju.das.jz@bp.renesas.com>
Reviewed-by: Lad Prabhakar <prabhakar.mahadev-lad.rj@bp.renesas.com>
Link: https://lore.kernel.org/r/20230315064501.21491-1-biju.das.jz@bp.renesas.comSigned-off-by: Vinod Koul <vkoul@kernel.org>

drivers/dma/sh/rz-dmac.c

@@ -20,6 +20,7 @@
 #include <linux/of_platform.h>
 #include <linux/platform_device.h>
 #include <linux/pm_runtime.h>
+#include <linux/reset.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 
@@ -92,6 +93,7 @@ struct rz_dmac_chan {
 struct rz_dmac {
 	struct dma_device engine;
 	struct device *dev;
+	struct reset_control *rstc;
 	void __iomem *base;
 	void __iomem *ext_base;
 
@@ -889,6 +891,11 @@ static int rz_dmac_probe(struct platform_device *pdev)
 	/* Initialize the channels. */
 	INIT_LIST_HEAD(&dmac->engine.channels);
 
+	dmac->rstc = devm_reset_control_array_get_exclusive(&pdev->dev);
+	if (IS_ERR(dmac->rstc))
+		return dev_err_probe(&pdev->dev, PTR_ERR(dmac->rstc),
+				     "failed to get resets\n");
+
 	pm_runtime_enable(&pdev->dev);
 	ret = pm_runtime_resume_and_get(&pdev->dev);
 	if (ret < 0) {
@@ -896,6 +903,10 @@ static int rz_dmac_probe(struct platform_device *pdev)
 		goto err_pm_disable;
 	}
 
+	ret = reset_control_deassert(dmac->rstc);
+	if (ret)
+		goto err_pm_runtime_put;
+
 	for (i = 0; i < dmac->n_channels; i++) {
 		ret = rz_dmac_chan_probe(dmac, &dmac->channels[i], i);
 		if (ret < 0)
@@ -940,6 +951,7 @@ static int rz_dmac_probe(struct platform_device *pdev)
 dma_register_err:
 	of_dma_controller_free(pdev->dev.of_node);
 err:
+	reset_control_assert(dmac->rstc);
 	channel_num = i ? i - 1 : 0;
 	for (i = 0; i < channel_num; i++) {
 		struct rz_dmac_chan *channel = &dmac->channels[i];
@@ -950,6 +962,7 @@ static int rz_dmac_probe(struct platform_device *pdev)
 				  channel->lmdesc.base_dma);
 	}
 
+err_pm_runtime_put:
 	pm_runtime_put(&pdev->dev);
 err_pm_disable:
 	pm_runtime_disable(&pdev->dev);
@@ -972,6 +985,7 @@ static int rz_dmac_remove(struct platform_device *pdev)
 	}
 	of_dma_controller_free(pdev->dev.of_node);
 	dma_async_device_unregister(&dmac->engine);
+	reset_control_assert(dmac->rstc);
 	pm_runtime_put(&pdev->dev);
 	pm_runtime_disable(&pdev->dev);