[PATCH v5 2/5] dma-engine: sun4i: Add has_reset option to quirk

[Csókás, Bence]

From: Mesih Kilinc <mesihkilinc at gmail.com>

Allwinner suniv F1C100s has a reset bit for DMA in CCU. Sun4i do not
has this bit but in order to support suniv we need to add it. So add
support for reset bit.

Signed-off-by: Mesih Kilinc <mesihkilinc at gmail.com>
[ csokas.bence: Rebased and addressed comments ]
Signed-off-by: Csókás, Bence <csokas.bence at prolan.hu>
---

Notes:
    Changes in v2:
    * Call reset_control_deassert() unconditionally, as it supports optional resets
    * Use dev_err_probe()
    * Whitespace
    Changes in v3:
    * More dev_err_probe() fixes
    Changes in v4:
    * Use return value of dev_err_probe()
    Changes in v5:
    * More whitespace

 drivers/dma/sun4i-dma.c | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/drivers/dma/sun4i-dma.c b/drivers/dma/sun4i-dma.c
index b2c1e4b9f696..9d1e3c51342d 100644
--- a/drivers/dma/sun4i-dma.c
+++ b/drivers/dma/sun4i-dma.c
@@ -15,6 +15,7 @@
 #include <linux/of_dma.h>
 #include <linux/of_device.h>
 #include <linux/platform_device.h>
+#include <linux/reset.h>
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 
@@ -159,6 +160,7 @@ struct sun4i_dma_config {
 	u8 ddma_drq_sdram;
 
 	u8 max_burst;
+	bool has_reset;
 };
 
 struct sun4i_dma_pchan {
@@ -208,6 +210,7 @@ struct sun4i_dma_dev {
 	int				irq;
 	spinlock_t			lock;
 	const struct sun4i_dma_config *cfg;
+	struct reset_control *rst;
 };
 
 static struct sun4i_dma_dev *to_sun4i_dma_dev(struct dma_device *dev)
@@ -1215,6 +1218,13 @@ static int sun4i_dma_probe(struct platform_device *pdev)
 		return PTR_ERR(priv->clk);
 	}
 
+	if (priv->cfg->has_reset) {
+		priv->rst = devm_reset_control_get_exclusive(&pdev->dev, NULL);
+		if (IS_ERR(priv->rst))
+			return dev_err_probe(&pdev->dev, PTR_ERR(priv->rst),
+					     "Failed to get reset control\n");
+	}
+
 	platform_set_drvdata(pdev, priv);
 	spin_lock_init(&priv->lock);
 
@@ -1287,6 +1297,14 @@ static int sun4i_dma_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	/* Deassert the reset control */
+	ret = reset_control_deassert(priv->rst);
+	if (ret) {
+		dev_err_probe(&pdev->dev, ret,
+			      "Failed to deassert the reset control\n");
+		goto err_clk_disable;
+	}
+
 	/*
 	 * Make sure the IRQs are all disabled and accounted for. The bootloader
 	 * likes to leave these dirty
@@ -1355,6 +1373,7 @@ static struct sun4i_dma_config sun4i_a10_dma_cfg = {
 	.ddma_drq_sdram		= SUN4I_DDMA_DRQ_TYPE_SDRAM,
 
 	.max_burst		= SUN4I_MAX_BURST,
+	.has_reset		= false,
 };
 
 static const struct of_device_id sun4i_dma_match[] = {
-- 
2.34.1